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gerrit-public.fairphone.software / platform / external / libpng / dcc3505c7bd0660876fc80110f8e3581900a186a / . / libpng.3
blob: 3a7ca6e666aeedb09ba3ee265240f790bbca1334 [file] [log] [blame]
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]1.TH LIBPNG 3 "March 31, 2011"
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]2.SH NAME
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]3libpng \- Portable Network Graphics (PNG) Reference Library 1.5.2
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4.SH SYNOPSIS
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]5\fI\fB
6
7\fB#include <png.h>\fP
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9\fI\fB
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]10
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]11\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]13\fI\fB
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Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]15\fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]17\fI\fB
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Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]19\fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP
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21\fI\fB
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23\fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
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25\fI\fB
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Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]27\fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]29\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]31\fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]32
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]33\fI\fB
34
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]35\fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]36
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]37\fI\fB
38
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]39\fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]40
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]41\fI\fB
42
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]43\fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]44
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]45\fI\fB
46
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]47\fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]48
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]49\fI\fB
50
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]51\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]52
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]53\fI\fB
54
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]55\fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]56
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]57\fI\fB
58
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]59\fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]60
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]61\fI\fB
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Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]63\fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]64
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]65\fI\fB
66
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]67\fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
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69\fI\fB
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71\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]72
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]73\fI\fB
74
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]75\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]77\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]79\fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]81\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]83\fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]85\fI\fB
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Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]87\fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP
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89\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]91\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]93\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]95\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]97\fI\fB
98
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]99\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]101\fI\fB
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Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]103\fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]104
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]105\fI\fB
106
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]107\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]108
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]109\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]111\fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]112
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]113\fI\fB
114
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]115\fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]116
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]117\fI\fB
118
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]119\fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]120
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]121\fI\fB
122
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]123\fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, double \fP\fI*green_y\fP\fB, double \fP\fI*blue_x\fP\fB, double \fI*blue_y\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]124
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]125\fI\fB
126
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]127\fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_uint_32 \fP\fI*green_x\fP\fB, png_uint_32 \fP\fI*green_y\fP\fB, png_uint_32 \fP\fI*blue_x\fP\fB, png_uint_32 \fI*blue_y\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]128
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]129\fI\fB
130
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]131\fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]132
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]133\fI\fB
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Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]135\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]137\fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]138
139\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]141\fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]142
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]143\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]145\fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]146
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]147\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]149\fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]150
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]151\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]153\fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]154
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]155\fI\fB
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John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]157\fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP
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159\fI\fB
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161\fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP
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163\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]165\fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]166
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]167\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]169\fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]170
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]171\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]173\fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]174
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]175\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]177\fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]178
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]179\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]181\fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]182
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]183\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]185\fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]186
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]187\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]189\fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]190
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]191\fI\fB
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John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]193\fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]194
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]195\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]197\fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, int \fP\fI*compression_type\fP\fB, int \fI*filter_type\fP\fB);\fP
198
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]199\fI\fB
200
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]201\fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]202
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]203\fI\fB
204
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]205\fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]206
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]207\fI\fB
208
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]209\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
210
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]211\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]212
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]213\fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]214
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]215\fI\fB
216
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]217\fBpng_const_bytep png_get_io_chunk_name (png_structp \fIpng_ptr\fP\fB);\fP
218
219\fI\fB
220
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]221\fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona63dbed2011-01-22 08:51:19 -0600[diff] [blame]222
223\fI\fB
224
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]225\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
226
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]227\fI\fB
228
Glenn Randers-Pehrsona63dbed2011-01-22 08:51:19 -0600[diff] [blame]229\fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP
230
231\fI\fB
232
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]233\fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]234
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]235\fI\fB
236
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]237\fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]238
239\fI\fB
240
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]241\fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]242
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]243\fI\fB
244
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]245\fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_charp \fP\fI*units\fP\fB, png_charpp \fI*params\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]246
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]247\fI\fB
248
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]249\fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]250
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]251\fI\fB
252
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]253\fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]254
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]255\fI\fB
256
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]257\fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]258
259\fI\fB
260
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]261\fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]262
263\fI\fB
264
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]265\fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]266
267\fI\fB
268
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]269\fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]270
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]271\fI\fB
272
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]273\fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]274
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]275\fI\fB
276
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]277\fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]278
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]279\fI\fB
280
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]281\fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr)
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]282
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]283\fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]284
285\fI\fB
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]286
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]287\fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]288
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]289\fI\fB
290
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]291\fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]292
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]293\fI\fB
294
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]295\fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]296
297\fI\fB
298
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]299\fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]300
301\fI\fB
302
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]303\fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]304
305\fI\fB
306
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]307\fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]308
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]309\fI\fB
310
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]311\fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]312
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]313\fI\fB
314
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]315\fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]316
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]317\fI\fB
318
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]319\fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]320
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]321\fI\fB
322
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]323\fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]324
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]325\fI\fB
326
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]327\fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]328
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]329\fI\fB
330
331\fB/* This function is really an inline macro. \fI*/
332
333\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
334
335\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]336
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]337\fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]338
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]339\fI\fB
340
341\fB/* This function is really an inline macro. \fI*/
342
343\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
344
345\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]346
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]347\fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]348
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]349\fI\fB
350
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]351\fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]352
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]353\fI\fB
354
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]355\fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]356
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]357\fI\fB
358
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]359\fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]360
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]361\fI\fB
362
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]363\fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]364
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]365\fI\fB
366
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]367\fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]368
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]369\fI\fB
370
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]371\fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]372
373\fI\fB
374
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]375\fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]376
377\fI\fB
378
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]379\fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]380
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]381\fI\fB
382
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]383\fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]384
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]385\fI\fB
386
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]387\fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]388
389\fI\fB
390
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]391\fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]392
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]393\fI\fB
394
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]395\fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]396
397\fI\fB
398
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]399\fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]400
401\fI\fB
402
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]403\fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]404
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]405\fI\fB
406
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]407\fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]408
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]409\fI\fB
410
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]411\fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]412
413\fI\fB
414
John Bowler0a5c9c02011-01-22 17:36:34 -0600[diff] [blame]415\fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]416
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]417\fI\fB
418
Glenn Randers-Pehrsonc1bfe682002-03-06 22:08:00 -0600[diff] [blame]419\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
420
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]421\fI\fB
422
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]423\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
424
425\fI\fB
426
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]427\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]428
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]429\fI\fB
430
Glenn Randers-Pehrsonf98726a2010-02-19 09:54:53 -0600[diff] [blame]431\fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP
432
433\fI\fB
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Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]435\fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]436
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]437\fI\fB
438
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]439\fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
440
441\fI\fB
442
443\fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
444
445\fI\fB
446
447\fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]448
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]449\fI\fB
450
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]451\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
452
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]453\fI\fB
454
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]455\fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP
456
457\fI\fB
458
459\fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP
460
461\fI\fB
462
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]463\fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
464
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]465\fI\fB
466
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]467\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
468
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]469\fI\fB
470
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]471\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
472
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]473\fI\fB
474
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]475\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
476
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]477\fI\fB
478
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]479\fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]480
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]481\fI\fB
482
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]483\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
484
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]485\fI\fB
486
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]487\fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
488
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]489\fI\fB
490
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]491\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
492
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]493\fI\fB
494
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]495\fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP
496
497\fI\fB
498
499\fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]500
501\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]502
503\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
504
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]505\fI\fB
506
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]507\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
508
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]509\fI\fB
510
511\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
512
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]513\fI\fB
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]514
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]515\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
516
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]517\fI\fB
518
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]519\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
520
521\fI\fB
522
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]523\fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
524
525\fI\fB
526
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]527\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
528
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]529\fI\fB
530
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]531\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
532
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]533\fI\fB
534
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]535\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB, double \fP\fIblue_x\fP\fB, double \fIblue_y\fP\fB);\fP
536
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]537\fI\fB
538
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]539\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\fB, png_uint_32 \fP\fIgreen_y\fP\fB, png_uint_32 \fP\fIblue_x\fP\fB, png_uint_32 \fIblue_y\fP\fB);\fP
540
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]541\fI\fB
542
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]543\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
544
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]545\fI\fB
546
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]547\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
548
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]549\fI\fB
550
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]551\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
552
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]553\fI\fB
554
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]555\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
556
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]557\fI\fB
558
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]559\fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]560
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]561\fI\fB
562
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]563\fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]564
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]565\fI\fB
566
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]567\fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]568
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]569\fI\fB
570
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]571\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]572
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]573\fI\fB
574
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]575\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsonc85f5f62011-02-13 05:56:07 -0600[diff] [blame]576
577\fI\fB
578
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]579\fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]580
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]581\fI\fB
582
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]583\fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]584
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]585\fI\fB
586
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]587\fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]588
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]589\fI\fB
590
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]591\fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]592
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]593\fI\fB
594
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]595\fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]596
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]597\fI\fB
598
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]599\fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP
600
601\fI\fB
602
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]603\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]604
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]605\fI\fB
606
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]607\fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]608
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]609\fI\fB
610
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]611\fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP
612
613\fI\fB
614
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]615\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]616
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]617\fI\fB
618
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]619\fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
620
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]621\fI\fB
622
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]623\fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]624
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]625\fI\fB
626
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]627\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]628
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]629\fI\fB
630
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]631\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]632
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]633\fI\fB
634
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]635\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]636
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]637\fI\fB
638
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]639\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]640
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]641\fI\fB
642
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]643\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
644
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]645\fI\fB
646
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]647\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]648
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]649\fI\fB
650
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]651\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]652
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]653\fI\fB
654
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]655\fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcompression_type\fP\fB, int \fIfilter_type\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]656
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]657\fI\fB
658
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]659\fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]660
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]661\fI\fB
662
Glenn Randers-Pehrson1e6ed732009-11-20 22:06:56 -0600[diff] [blame]663\fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP
664
665\fI\fB
666
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]667\fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP
668
669\fI\fB
670
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]671\fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
672
673\fI\fB
674
675\fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]676
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]677\fI\fB
678
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]679\fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]680
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]681\fI\fB
682
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]683\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]684
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]685\fI\fB
686
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]687\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]688
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]689\fI\fB
690
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]691\fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]692
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]693\fI\fB
694
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]695\fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, png_charpp \fIparams\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]696
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]697\fI\fB
698
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]699\fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]700
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]701\fI\fB
702
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]703\fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]704
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]705\fI\fB
706
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]707\fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]708
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]709\fI\fB
710
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]711\fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP
712
713\fI\fB
714
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]715\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]716
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]717\fI\fB
718
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]719\fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]720
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]721\fI\fB
722
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]723\fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
724
725\fI\fB
726
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]727\fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]728
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]729\fI\fB
730
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]731\fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
732
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]733\fI\fB
734
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]735\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]736
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]737\fI\fB
738
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]739\fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
740
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]741\fI\fB
742
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]743\fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]744
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]745\fI\fB
746
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]747\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
748
749\fI\fB
750
751\fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP
752
753\fI\fB
754
755\fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
756
757\fI\fB
758
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]759\fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]760
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]761\fI\fB
762
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]763\fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]764
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]765\fI\fB
766
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]767\fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]768
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]769\fI\fB
770
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]771\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]772
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]773\fI\fB
774
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]775\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]776
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]777\fI\fB
778
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]779\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]780
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]781\fI\fB
782
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]783\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]784
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]785\fI\fB
786
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]787\fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP
788
789\fI\fB
790
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]791\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]792
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]793\fI\fB
794
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]795\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]796
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]797\fI\fB
798
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]799\fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]800
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]801\fI\fB
802
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]803\fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]804
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]805\fI\fB
806
Glenn Randers-Pehrsonf3c51e42011-01-15 10:25:25 -0600[diff] [blame]807\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]808
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]809\fI\fB
810
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]811\fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]812
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]813\fI\fB
814
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]815\fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
816
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]817\fI\fB
818
Glenn Randers-Pehrsonbb98bcb2011-01-22 16:27:39 -0600[diff] [blame]819\fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]820
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]821\fI\fB
822
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]823\fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP
824
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]825\fI\fB
826
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]827\fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]828
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]829\fI\fB
830
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]831\fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]832
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]833\fI\fB
834
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]835\fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]836
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]837\fI\fB
838
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]839\fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]840
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]841\fI\fB
842
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]843\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]844
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]845\fI\fB
846
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]847\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]848
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]849\fI\fB
850
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]851\fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]852
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]853\fI\fB
854
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]855\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]856
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]857\fI\fB
858
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]859\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]860
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]861\fI\fB
862
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]863\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]864
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]865\fI\fB
866
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]867\fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]868
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]869\fI\fB
870
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]871\fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]872
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]873\fI\fB
874
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]875\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]876
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]877\fI\fB
878
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]879\fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]880
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]881\fI\fB
882
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]883\fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]884
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]885\fI\fB
886
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]887\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
888
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]889\fI\fB
890
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]891\fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]892
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]893\fI\fB
894
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]895\fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]896
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]897\fI\fB
898
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]899\fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]900
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]901\fI\fB
902
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]903\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
904
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]905\fI\fB
906
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]907\fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP
908
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]909\fI\fB
910
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]911\fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP
912
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]913\fI\fB
914
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]915.SH DESCRIPTION
916The
917.I libpng
918library supports encoding, decoding, and various manipulations of
919the Portable Network Graphics (PNG) format image files. It uses the
920.IR zlib(3)
921compression library.
Glenn Randers-Pehrson557b2562010-10-17 12:55:04 -0500[diff] [blame]922Following is a copy of the libpng-manual.txt file that accompanies libpng.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]923.SH LIBPNG.TXT
Glenn Randers-Pehrson557b2562010-10-17 12:55:04 -0500[diff] [blame]924libpng-manual.txt - A description on how to use and modify libpng
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]925
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]926 libpng version 1.5.2 - March 31, 2011
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]927 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]928 <glennrp at users.sourceforge.net>
Glenn Randers-Pehrson9f45c8e2011-01-15 19:35:03 -0600[diff] [blame]929 Copyright (c) 1998-2011 Glenn Randers-Pehrson
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]930
Glenn Randers-Pehrsonbfbf8652009-06-26 21:46:52 -0500[diff] [blame]931 This document is released under the libpng license.
Glenn Randers-Pehrsonc332bbc2009-06-25 13:43:50 -0500[diff] [blame]932 For conditions of distribution and use, see the disclaimer
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]933 and license in png.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]934
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]935 Based on:
936
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]937 libpng versions 0.97, January 1998, through 1.5.2 - March 31, 2011
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]938 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrson9f45c8e2011-01-15 19:35:03 -0600[diff] [blame]939 Copyright (c) 1998-2011 Glenn Randers-Pehrson
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]940
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]941 libpng 1.0 beta 6 version 0.96 May 28, 1997
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]942 Updated and distributed by Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]943 Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]944
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]945 libpng 1.0 beta 2 - version 0.88 January 26, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]946 For conditions of distribution and use, see copyright
947 notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]948 Schalnat, Group 42, Inc.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]949
950 Updated/rewritten per request in the libpng FAQ
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]951 Copyright (c) 1995, 1996 Frank J. T. Wojcik
952 December 18, 1995 & January 20, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]953
954.SH I. Introduction
955
956This file describes how to use and modify the PNG reference library
957(known as libpng) for your own use. There are five sections to this
958file: introduction, structures, reading, writing, and modification and
959configuration notes for various special platforms. In addition to this
960file, example.c is a good starting point for using the library, as
961it is heavily commented and should include everything most people
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]962will need. We assume that libpng is already installed; see the
963INSTALL file for instructions on how to install libpng.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]964
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]965For examples of libpng usage, see the files "example.c", "pngtest.c",
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]966and the files in the "contrib" directory, all of which are included in
967the libpng distribution.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]968
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]969Libpng was written as a companion to the PNG specification, as a way
970of reducing the amount of time and effort it takes to support the PNG
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]971file format in application programs.
972
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]973The PNG specification (second edition), November 2003, is available as
974a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
975<http://www.w3.org/TR/2003/REC-PNG-20031110/
976The W3C and ISO documents have identical technical content.
977
978The PNG-1.2 specification is available at
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]979<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
980to the PNG specification (second edition) but has some additional material.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]981
982The PNG-1.0 specification is available
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]983as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]984W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
985
986Some additional chunks are described in the special-purpose public chunks
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]987documents at <http://www.libpng.org/pub/png/documents/>.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]988
989Other information
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]990about PNG, and the latest version of libpng, can be found at the PNG home
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]991page, <http://www.libpng.org/pub/png/>.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]992
993Most users will not have to modify the library significantly; advanced
994users may want to modify it more. All attempts were made to make it as
995complete as possible, while keeping the code easy to understand.
996Currently, this library only supports C. Support for other languages
997is being considered.
998
999Libpng has been designed to handle multiple sessions at one time,
1000to be easily modifiable, to be portable to the vast majority of
1001machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
1002to use. The ultimate goal of libpng is to promote the acceptance of
1003the PNG file format in whatever way possible. While there is still
1004work to be done (see the TODO file), libpng should cover the
1005majority of the needs of its users.
1006
1007Libpng uses zlib for its compression and decompression of PNG files.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1008Further information about zlib, and the latest version of zlib, can
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]1009be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1010The zlib compression utility is a general purpose utility that is
1011useful for more than PNG files, and can be used without libpng.
1012See the documentation delivered with zlib for more details.
1013You can usually find the source files for the zlib utility wherever you
1014find the libpng source files.
1015
1016Libpng is thread safe, provided the threads are using different
1017instances of the structures. Each thread should have its own
1018png_struct and png_info instances, and thus its own image.
1019Libpng does not protect itself against two threads using the
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1020same instance of a structure.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1021
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1022.SH II. Structures
1023
1024There are two main structures that are important to libpng, png_struct
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1025and png_info. Both are internal structures that are no longer exposed
1026in the libpng interface (as of libpng 1.5.0).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1027
1028The png_info structure is designed to provide information about the
1029PNG file. At one time, the fields of png_info were intended to be
1030directly accessible to the user. However, this tended to cause problems
1031with applications using dynamically loaded libraries, and as a result
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]1032a set of interface functions for png_info (the png_get_*() and png_set_*()
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1033functions) was developed.
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]1034
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1035The png_struct structure is the object used by the library to decode a
1036single image. As of 1.5.0 this structure is also not exposed.
1037
1038Almost all libpng APIs require a pointer to a png_struct as the first argument.
1039Many (in particular the png_set and png_get APIs) also require a pointer
1040to png_info as the second argument. Some application visible macros
1041defined in png.h designed for basic data access (reading and writing
1042integers in the PNG format) break this rule, but it's almost always safe
1043to assume that a (png_struct*) has to be passed to call an API function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1044
1045The png.h header file is an invaluable reference for programming with libpng.
1046And while I'm on the topic, make sure you include the libpng header file:
1047
1048#include <png.h>
1049
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1050.SS Types
1051
1052The png.h header file defines a number of integral types used by the
1053APIs. Most of these are fairly obvious; for example types corresponding
1054to integers of particular sizes and types for passing color values.
1055
1056One exception is how non-integral numbers are handled. For application
1057convenience most APIs that take such numbers have C (double) arguments,
1058however internally PNG, and libpng, use 32 bit signed integers and encode
1059the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
1060macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
1061which is simply (png_int_32).
1062
1063All APIs that take (double) arguments also have an matching API that
1064takes the corresponding fixed point integer arguments. The fixed point
1065API has the same name as the floating point one with _fixed appended.
1066The actual range of values permitted in the APIs is frequently less than
1067the full range of (png_fixed_point) (-21474 to +21474). When APIs require
1068a non-negative argument the type is recorded as png_uint_32 above. Consult
1069the header file and the text below for more information.
1070
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]1071Special care must be take with sCAL chunk handling because the chunk itself
1072uses non-integral values encoded as strings containing decimal floating point
1073numbers. See the comments in the header file.
1074
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]1075.SS Configuration
1076
1077The main header file function declarations are frequently protected by C
1078preprocessing directives of the form:
1079
1080 #ifdef PNG_feature_SUPPORTED
1081 declare-function
1082 #endif
1083
1084The library can be built without support for these APIs, although a
1085standard build will have all implemented APIs. Application programs
1086should check the feature macros before using an API for maximum
1087portability. From libpng 1.5.0 the feature macros set during the build
1088of libpng are recorded in the header file "pnglibconf.h" and this file
1089is always included by png.h.
1090
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]1091If you don't need to change the library configuration from the default skip to
1092the next section ("Reading").
1093
1094Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
1095of the build project files in the 'projects' directory simply copy
1096scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
1097systems do not permit easy auto-configuration of the library - they only
1098support the default configuration.
1099
1100The easiest way to make minor changes to the libpng configuration when
1101auto-configuration is supported is to add definitions to the command line
1102using (typically) CPPFLAGS. For example:
1103
1104CPPFLAGS=-DPNG_NO_FLOATING_ARITHMETIC
1105
1106will change the internal libpng math implementation for gamma correction and
1107other arithmetic calculations to fixed point, avoiding the need for fast
1108floating point support. The result can be seen in the generated pnglibconf.h -
1109make sure it contains the changed feature macro setting.
1110
1111If you need to make more extensive configuration changes - more than one or two
1112feature macro settings - you can either add -DPNG_USER_CONFIG to the build
1113command line and put a list of feature macro settings in pngusr.h or you can set
1114DFA_XTRA (a makefile variable) to a file containing the same information in the
1115form of 'option' settings.
1116
1117A. Changing pnglibconf.h
1118
1119A variety of methods exist to build libpng. Not all of these support
1120reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
1121rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
1122
1123Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt and changing
1124the lines defining the supported features, paying very close attention to the
1125'option' information in scripts/pnglibconf.dfa that describes those features and
1126their requirements. This is easy to get wrong.
1127
1128B. Configuration using DFA_XTRA
1129
1130Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
1131variant such as 'nawk' or 'gawk', is available. The configure build will
1132automatically find an appropriate awk and build pnglibconf.h.
1133scripts/pnglibconf.mak contains a set of make rules for doing the same thing if
1134configure is not used, and many of the makefiles in the scripts directory use
1135this approach.
1136
1137When rebuilding simply write new file containing changed options and set
1138DFA_XTRA to the name of this file. This causes the build to append the new file
1139to the end of scripts/pnglibconf.dfa. pngusr.dfa should contain lines of the
1140following forms:
1141
1142everything = off
1143
1144This turns all optional features off. Include it at the start of pngusr.dfa to
1145make it easier to build a minimal configuration. You will need to turn at least
1146some features on afterward to enable either reading or writing code, or both.
1147
1148option feature on
1149option feature off
1150
1151Enable or disable a single feature. This will automatically enable other
1152features required by a feature that is turned on or disable other features that
1153require a feature which is turned off. Conflicting settings will cause an error
1154message to be emitted by awk.
1155
1156setting feature default value
1157
1158Changes the default value of setting 'feature' to 'value'. There are a small
1159number of settings listed at the top of pnglibconf.h, they are documented in the
1160source code. Most of these values have performance implications for the library
1161but most of them have no visible effect on the API. Some can also be overridden
1162from the API.
1163
1164C. Configuration using PNG_USR_CONFIG
1165
1166If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file
1167pngusr.h will automatically be included before the options in
1168scripts/pnglibconf.dfa are processed. pngusr.h should contain only macro
1169definitions turning features on or off or setting settings.
1170
1171Apart from the global setting "everything = off" all the options listed above
1172can be set using macros in pngusr.h:
1173
1174#define PNG_feature_SUPPORTED
1175
1176is equivalent to:
1177
1178option feature on
1179
1180#define PNG_NO_feature
1181
1182is equivalent to:
1183
1184option feature off
1185
1186#define PNG_feature value
1187
1188is equivalent to:
1189
1190setting feature default value
1191
1192Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
1193pngusr file you supply override the contents of scripts/pnglibconf.dfa
1194
1195If confusing or incomprehensible behavior results it is possible to
1196examine the intermediate file pnglibconf.dfn to find the full set of
1197dependency information for each setting and option. Simply locate the
1198feature in the file and read the C comments that precede it.
1199
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1200.SH III. Reading
1201
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1202We'll now walk you through the possible functions to call when reading
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1203in a PNG file sequentially, briefly explaining the syntax and purpose
1204of each one. See example.c and png.h for more detail. While
1205progressive reading is covered in the next section, you will still
1206need some of the functions discussed in this section to read a PNG
1207file.
1208
1209.SS Setup
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1210
1211You will want to do the I/O initialization(*) before you get into libpng,
1212so if it doesn't work, you don't have much to undo. Of course, you
1213will also want to insure that you are, in fact, dealing with a PNG
1214file. Libpng provides a simple check to see if a file is a PNG file.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1215To use it, pass in the first 1 to 8 bytes of the file to the function
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]1216png_sig_cmp(), and it will return 0 (false) if the bytes match the
1217corresponding bytes of the PNG signature, or nonzero (true) otherwise.
1218Of course, the more bytes you pass in, the greater the accuracy of the
1219prediction.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1220
1221If you are intending to keep the file pointer open for use in libpng,
1222you must ensure you don't read more than 8 bytes from the beginning
1223of the file, and you also have to make a call to png_set_sig_bytes_read()
1224with the number of bytes you read from the beginning. Libpng will
1225then only check the bytes (if any) that your program didn't read.
1226
1227(*): If you are not using the standard I/O functions, you will need
1228to replace them with custom functions. See the discussion under
1229Customizing libpng.
1230
1231
1232 FILE *fp = fopen(file_name, "rb");
1233 if (!fp)
1234 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1235 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1236 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1237
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1238 fread(header, 1, number, fp);
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]1239 is_png = !png_sig_cmp(header, 0, number);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1240
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1241 if (!is_png)
1242 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1243 return (NOT_PNG);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1244 }
1245
1246
1247Next, png_struct and png_info need to be allocated and initialized. In
1248order to ensure that the size of these structures is correct even with a
1249dynamically linked libpng, there are functions to initialize and
1250allocate the structures. We also pass the library version, optional
1251pointers to error handling functions, and a pointer to a data struct for
1252use by the error functions, if necessary (the pointer and functions can
1253be NULL if the default error handlers are to be used). See the section
1254on Changes to Libpng below regarding the old initialization functions.
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]1255The structure allocation functions quietly return NULL if they fail to
1256create the structure, so your application should check for that.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1257
1258 png_structp png_ptr = png_create_read_struct
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1259 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1260 user_error_fn, user_warning_fn);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1261
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1262 if (!png_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1263 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1264
1265 png_infop info_ptr = png_create_info_struct(png_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1266
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1267 if (!info_ptr)
1268 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1269 png_destroy_read_struct(&png_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1270 (png_infopp)NULL, (png_infopp)NULL);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1271 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1272 }
1273
1274 png_infop end_info = png_create_info_struct(png_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1275
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1276 if (!end_info)
1277 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1278 png_destroy_read_struct(&png_ptr, &info_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1279 (png_infopp)NULL);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1280 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1281 }
1282
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1283If you want to use your own memory allocation routines,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1284use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1285png_create_read_struct_2() instead of png_create_read_struct():
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1286
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1287 png_structp png_ptr = png_create_read_struct_2
1288 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
1289 user_error_fn, user_warning_fn, (png_voidp)
1290 user_mem_ptr, user_malloc_fn, user_free_fn);
1291
1292The error handling routines passed to png_create_read_struct()
1293and the memory alloc/free routines passed to png_create_struct_2()
1294are only necessary if you are not using the libpng supplied error
1295handling and memory alloc/free functions.
1296
1297When libpng encounters an error, it expects to longjmp back
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1298to your routine. Therefore, you will need to call setjmp and pass
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1299your png_jmpbuf(png_ptr). If you read the file from different
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1300routines, you will need to update the jmpbuf field every time you enter
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1301a new routine that will call a png_*() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1302
1303See your documentation of setjmp/longjmp for your compiler for more
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1304information on setjmp/longjmp. See the discussion on libpng error
1305handling in the Customizing Libpng section below for more information
1306on the libpng error handling. If an error occurs, and libpng longjmp's
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1307back to your setjmp, you will want to call png_destroy_read_struct() to
1308free any memory.
1309
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1310 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1311 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1312 png_destroy_read_struct(&png_ptr, &info_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1313 &end_info);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1314 fclose(fp);
1315 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1316 }
1317
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1318If you would rather avoid the complexity of setjmp/longjmp issues,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]1319you can compile libpng with PNG_NO_SETJMP, in which case
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1320errors will result in a call to PNG_ABORT() which defaults to abort().
1321
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]1322You can #define PNG_ABORT() to a function that does something
1323more useful than abort(), as long as your function does not
1324return.
1325
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1326Now you need to set up the input code. The default for libpng is to
1327use the C function fread(). If you use this, you will need to pass a
1328valid FILE * in the function png_init_io(). Be sure that the file is
1329opened in binary mode. If you wish to handle reading data in another
1330way, you need not call the png_init_io() function, but you must then
1331implement the libpng I/O methods discussed in the Customizing Libpng
1332section below.
1333
1334 png_init_io(png_ptr, fp);
1335
1336If you had previously opened the file and read any of the signature from
1337the beginning in order to see if this was a PNG file, you need to let
1338libpng know that there are some bytes missing from the start of the file.
1339
1340 png_set_sig_bytes(png_ptr, number);
1341
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]1342You can change the zlib compression buffer size to be used while
1343reading compressed data with
1344
1345 png_set_compression_buffer_size(png_ptr, buffer_size);
1346
1347where the default size is 8192 bytes. Note that the buffer size
1348is changed immediately and the buffer is reallocated immediately,
1349instead of setting a flag to be acted upon later.
1350
Glenn Randers-Pehrson9dd1cdf2011-01-06 21:42:36 -0600[diff] [blame]1351If you want CRC errors to be handled in a different manner than
1352the default, use
1353
1354 png_set_crc_action(png_ptr, crit_action, ancil_action);
1355
1356The values for png_set_crc_action() say how libpng is to handle CRC errors in
1357ancillary and critical chunks, and whether to use the data contained
1358therein. Note that it is impossible to "discard" data in a critical
1359chunk.
1360
1361Choices for (int) crit_action are
1362 PNG_CRC_DEFAULT 0 error/quit
1363 PNG_CRC_ERROR_QUIT 1 error/quit
1364 PNG_CRC_WARN_USE 3 warn/use data
1365 PNG_CRC_QUIET_USE 4 quiet/use data
1366 PNG_CRC_NO_CHANGE 5 use the current value
1367
1368Choices for (int) ancil_action are
1369 PNG_CRC_DEFAULT 0 error/quit
1370 PNG_CRC_ERROR_QUIT 1 error/quit
1371 PNG_CRC_WARN_DISCARD 2 warn/discard data
1372 PNG_CRC_WARN_USE 3 warn/use data
1373 PNG_CRC_QUIET_USE 4 quiet/use data
1374 PNG_CRC_NO_CHANGE 5 use the current value
1375
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1376.SS Setting up callback code
1377
1378You can set up a callback function to handle any unknown chunks in the
1379input stream. You must supply the function
1380
Glenn Randers-Pehrson81ce8892011-01-24 08:04:37 -0600[diff] [blame]1381 read_chunk_callback(png_structp png_ptr,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1382 png_unknown_chunkp chunk);
1383 {
1384 /* The unknown chunk structure contains your
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1385 chunk data, along with similar data for any other
1386 unknown chunks: */
1387
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1388 png_byte name[5];
1389 png_byte *data;
1390 png_size_t size;
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1391
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1392 /* Note that libpng has already taken care of
1393 the CRC handling */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1394
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1395 /* put your code here. Search for your chunk in the
1396 unknown chunk structure, process it, and return one
1397 of the following: */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1398
1399 return (-n); /* chunk had an error */
1400 return (0); /* did not recognize */
1401 return (n); /* success */
1402 }
1403
1404(You can give your function another name that you like instead of
1405"read_chunk_callback")
1406
1407To inform libpng about your function, use
1408
1409 png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
1410 read_chunk_callback);
1411
1412This names not only the callback function, but also a user pointer that
1413you can retrieve with
1414
1415 png_get_user_chunk_ptr(png_ptr);
1416
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1417If you call the png_set_read_user_chunk_fn() function, then all unknown
1418chunks will be saved when read, in case your callback function will need
1419one or more of them. This behavior can be changed with the
1420png_set_keep_unknown_chunks() function, described below.
1421
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1422At this point, you can set up a callback function that will be
1423called after each row has been read, which you can use to control
1424a progress meter or the like. It's demonstrated in pngtest.c.
1425You must supply a function
1426
Glenn Randers-Pehrson81ce8892011-01-24 08:04:37 -0600[diff] [blame]1427 void read_row_callback(png_structp png_ptr,
1428 png_uint_32 row, int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1429 {
1430 /* put your code here */
1431 }
1432
1433(You can give it another name that you like instead of "read_row_callback")
1434
1435To inform libpng about your function, use
1436
1437 png_set_read_status_fn(png_ptr, read_row_callback);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1438
John Bowler59010e52011-02-16 06:16:31 -0600[diff] [blame]1439When this function is called the row has already been completely processed and
1440the 'row' and 'pass' refer to the next row to be handled. For the
1441non-interlaced case the row that was just handled is simply one less than the
1442passed in row number, and pass will always be 0. For the interlaced case the
1443same applies unless the row value is 0, in which case the row just handled was
1444the last one from one of the preceding passes. Because interlacing may skip a
1445pass you cannot be sure that the preceding pass is just 'pass-1', if you really
1446need to know what the last pass is record (row,pass) from the callback and use
1447the last recorded value each time.
1448
1449As with the user transform you can find the output row using the
1450PNG_ROW_FROM_PASS_ROW macro.
1451
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1452.SS Unknown-chunk handling
1453
1454Now you get to set the way the library processes unknown chunks in the
1455input PNG stream. Both known and unknown chunks will be read. Normal
1456behavior is that known chunks will be parsed into information in
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1457various info_ptr members while unknown chunks will be discarded. This
1458behavior can be wasteful if your application will never use some known
1459chunk types. To change this, you can call:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1460
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]1461 png_set_keep_unknown_chunks(png_ptr, keep,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1462 chunk_list, num_chunks);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1463 keep - 0: default unknown chunk handling
1464 1: ignore; do not keep
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1465 2: keep only if safe-to-copy
1466 3: keep even if unsafe-to-copy
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1467
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1468 You can use these definitions:
1469 PNG_HANDLE_CHUNK_AS_DEFAULT 0
1470 PNG_HANDLE_CHUNK_NEVER 1
1471 PNG_HANDLE_CHUNK_IF_SAFE 2
1472 PNG_HANDLE_CHUNK_ALWAYS 3
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1473
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1474 chunk_list - list of chunks affected (a byte string,
1475 five bytes per chunk, NULL or '\0' if
1476 num_chunks is 0)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1477
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1478 num_chunks - number of chunks affected; if 0, all
Glenn Randers-Pehrsondff799e2004-08-07 21:42:49 -0500[diff] [blame]1479 unknown chunks are affected. If nonzero,
1480 only the chunks in the list are affected
1481
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1482Unknown chunks declared in this way will be saved as raw data onto a
1483list of png_unknown_chunk structures. If a chunk that is normally
1484known to libpng is named in the list, it will be handled as unknown,
1485according to the "keep" directive. If a chunk is named in successive
1486instances of png_set_keep_unknown_chunks(), the final instance will
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1487take precedence. The IHDR and IEND chunks should not be named in
1488chunk_list; if they are, libpng will process them normally anyway.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1489
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1490Here is an example of the usage of png_set_keep_unknown_chunks(),
1491where the private "vpAg" chunk will later be processed by a user chunk
1492callback function:
1493
1494 png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
1495
1496 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1497 png_byte unused_chunks[]=
1498 {
1499 104, 73, 83, 84, (png_byte) '\0', /* hIST */
1500 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
1501 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
1502 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
1503 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
1504 116, 73, 77, 69, (png_byte) '\0', /* tIME */
1505 };
1506 #endif
1507
1508 ...
1509
1510 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1511 /* ignore all unknown chunks: */
1512 png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1513
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1514 /* except for vpAg: */
1515 png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1516
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1517 /* also ignore unused known chunks: */
1518 png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
1519 (int)sizeof(unused_chunks)/5);
1520 #endif
1521
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]1522.SS User limits
1523
1524The PNG specification allows the width and height of an image to be as
1525large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
1526Since very few applications really need to process such large images,
1527we have imposed an arbitrary 1-million limit on rows and columns.
1528Larger images will be rejected immediately with a png_error() call. If
1529you wish to override this limit, you can use
1530
1531 png_set_user_limits(png_ptr, width_max, height_max);
1532
1533to set your own limits, or use width_max = height_max = 0x7fffffffL
1534to allow all valid dimensions (libpng may reject some very large images
1535anyway because of potential buffer overflow conditions).
1536
1537You should put this statement after you create the PNG structure and
1538before calling png_read_info(), png_read_png(), or png_process_data().
1539If you need to retrieve the limits that are being applied, use
1540
1541 width_max = png_get_user_width_max(png_ptr);
1542 height_max = png_get_user_height_max(png_ptr);
1543
1544The PNG specification sets no limit on the number of ancillary chunks
1545allowed in a PNG datastream. You can impose a limit on the total number
1546of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
1547
1548 png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
1549
1550where 0x7fffffffL means unlimited. You can retrieve this limit with
1551
1552 chunk_cache_max = png_get_chunk_cache_max(png_ptr);
1553
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]1554This limit also applies to the number of buffers that can be allocated
1555by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks.
1556
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]1557You can also set a limit on the amount of memory that a compressed chunk
1558other than IDAT can occupy, with
1559
1560 png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
1561
1562and you can retrieve the limit with
1563
1564 chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
1565
1566Any chunks that would cause either of these limits to be exceeded will
1567be ignored.
1568
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1569.SS The high-level read interface
1570
1571At this point there are two ways to proceed; through the high-level
1572read interface, or through a sequence of low-level read operations.
1573You can use the high-level interface if (a) you are willing to read
1574the entire image into memory, and (b) the input transformations
1575you want to do are limited to the following set:
1576
1577 PNG_TRANSFORM_IDENTITY No transformation
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1578 PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to
1579 8 bits
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1580 PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1581 PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
1582 samples to bytes
1583 PNG_TRANSFORM_PACKSWAP Change order of packed
1584 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1585 PNG_TRANSFORM_EXPAND Perform set_expand()
1586 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1587 PNG_TRANSFORM_SHIFT Normalize pixels to the
1588 sBIT depth
1589 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
1590 to BGRA
1591 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
1592 to AG
1593 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
1594 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1595 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson99708d52009-06-29 17:30:00 -0500[diff] [blame]1596 PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
1597 to RGB (or GA to RGBA)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1598
1599(This excludes setting a background color, doing gamma transformation,
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]1600quantizing, and setting filler.) If this is the case, simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1601
1602 png_read_png(png_ptr, info_ptr, png_transforms, NULL)
1603
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1604where png_transforms is an integer containing the bitwise OR of some
1605set of transformation flags. This call is equivalent to png_read_info(),
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1606followed the set of transformations indicated by the transform mask,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1607then png_read_image(), and finally png_read_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1608
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1609(The final parameter of this call is not yet used. Someday it might point
1610to transformation parameters required by some future input transform.)
1611
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]1612You must use png_transforms and not call any png_set_transform() functions
1613when you use png_read_png().
1614
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1615After you have called png_read_png(), you can retrieve the image data
1616with
1617
1618 row_pointers = png_get_rows(png_ptr, info_ptr);
1619
1620where row_pointers is an array of pointers to the pixel data for each row:
1621
1622 png_bytep row_pointers[height];
1623
1624If you know your image size and pixel size ahead of time, you can allocate
1625row_pointers prior to calling png_read_png() with
1626
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1627 if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]1628 png_error (png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1629 "Image is too tall to process in memory");
1630
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]1631 if (width > PNG_UINT_32_MAX/pixel_size)
1632 png_error (png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1633 "Image is too wide to process in memory");
1634
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1635 row_pointers = png_malloc(png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1636 height*png_sizeof(png_bytep));
1637
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1638 for (int i=0; i<height, i++)
1639 row_pointers[i]=NULL; /* security precaution */
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1640
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1641 for (int i=0; i<height, i++)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1642 row_pointers[i]=png_malloc(png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1643 width*pixel_size);
1644
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]1645 png_set_rows(png_ptr, info_ptr, &row_pointers);
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1646
1647Alternatively you could allocate your image in one big block and define
1648row_pointers[i] to point into the proper places in your block.
1649
1650If you use png_set_rows(), the application is responsible for freeing
1651row_pointers (and row_pointers[i], if they were separately allocated).
1652
1653If you don't allocate row_pointers ahead of time, png_read_png() will
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1654do it, and it'll be free'ed by libpng when you call png_destroy_*().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1655
1656.SS The low-level read interface
1657
1658If you are going the low-level route, you are now ready to read all
1659the file information up to the actual image data. You do this with a
1660call to png_read_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1661
1662 png_read_info(png_ptr, info_ptr);
1663
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1664This will process all chunks up to but not including the image data.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1665
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1666.SS Querying the info structure
1667
1668Functions are used to get the information from the info_ptr once it
1669has been read. Note that these fields may not be completely filled
1670in until png_read_end() has read the chunk data following the image.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1671
1672 png_get_IHDR(png_ptr, info_ptr, &width, &height,
1673 &bit_depth, &color_type, &interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1674 &compression_type, &filter_method);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1675
1676 width - holds the width of the image
1677 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1678
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1679 height - holds the height of the image
1680 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1681
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1682 bit_depth - holds the bit depth of one of the
1683 image channels. (valid values are
1684 1, 2, 4, 8, 16 and depend also on
1685 the color_type. See also
1686 significant bits (sBIT) below).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1687
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1688 color_type - describes which color/alpha channels
1689 are present.
1690 PNG_COLOR_TYPE_GRAY
1691 (bit depths 1, 2, 4, 8, 16)
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1692 PNG_COLOR_TYPE_GRAY_ALPHA
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1693 (bit depths 8, 16)
1694 PNG_COLOR_TYPE_PALETTE
1695 (bit depths 1, 2, 4, 8)
1696 PNG_COLOR_TYPE_RGB
1697 (bit_depths 8, 16)
1698 PNG_COLOR_TYPE_RGB_ALPHA
1699 (bit_depths 8, 16)
1700
1701 PNG_COLOR_MASK_PALETTE
1702 PNG_COLOR_MASK_COLOR
1703 PNG_COLOR_MASK_ALPHA
1704
Glenn Randers-Pehrson2cb633b2011-01-21 08:31:29 -0600[diff] [blame]1705 interlace_type - (PNG_INTERLACE_NONE or
1706 PNG_INTERLACE_ADAM7)
1707
1708 compression_type - (must be PNG_COMPRESSION_TYPE_BASE
1709 for PNG 1.0)
1710
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1711 filter_method - (must be PNG_FILTER_TYPE_BASE
1712 for PNG 1.0, and can also be
1713 PNG_INTRAPIXEL_DIFFERENCING if
1714 the PNG datastream is embedded in
1715 a MNG-1.0 datastream)
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1716
1717 Any or all of interlace_type, compression_type, or
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1718 filter_method can be NULL if you are
1719 not interested in their values.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1720
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1721 Note that png_get_IHDR() returns 32-bit data into
1722 the application's width and height variables.
1723 This is an unsafe situation if these are 16-bit
1724 variables. In such situations, the
1725 png_get_image_width() and png_get_image_height()
1726 functions described below are safer.
1727
1728 width = png_get_image_width(png_ptr,
1729 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1730
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1731 height = png_get_image_height(png_ptr,
1732 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1733
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1734 bit_depth = png_get_bit_depth(png_ptr,
1735 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1736
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1737 color_type = png_get_color_type(png_ptr,
1738 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1739
Glenn Randers-Pehrson2cb633b2011-01-21 08:31:29 -0600[diff] [blame]1740 interlace_type = png_get_interlace_type(png_ptr,
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1741 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1742
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1743 compression_type = png_get_compression_type(png_ptr,
1744 info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1745
Glenn Randers-Pehrson2cb633b2011-01-21 08:31:29 -0600[diff] [blame]1746 filter_method = png_get_filter_type(png_ptr,
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1747 info_ptr);
1748
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1749 channels = png_get_channels(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1750
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1751 channels - number of channels of info for the
1752 color type (valid values are 1 (GRAY,
1753 PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
1754 4 (RGB_ALPHA or RGB + filler byte))
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1755
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1756 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1757
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1758 rowbytes - number of bytes needed to hold a row
1759
1760 signature = png_get_signature(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1761
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1762 signature - holds the signature read from the
1763 file (if any). The data is kept in
1764 the same offset it would be if the
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1765 whole signature were read (i.e. if an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1766 application had already read in 4
1767 bytes of signature before starting
1768 libpng, the remaining 4 bytes would
1769 be in signature[4] through signature[7]
1770 (see png_set_sig_bytes())).
1771
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1772These are also important, but their validity depends on whether the chunk
1773has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
1774png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
1775data has been read, or zero if it is missing. The parameters to the
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1776png_get_<chunk> are set directly if they are simple data types, or a
1777pointer into the info_ptr is returned for any complex types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1778
1779 png_get_PLTE(png_ptr, info_ptr, &palette,
1780 &num_palette);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1781
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1782 palette - the palette for the file
1783 (array of png_color)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1784
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1785 num_palette - number of entries in the palette
1786
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]1787 png_get_gAMA(png_ptr, info_ptr, &file_gamma);
Glenn Randers-Pehrson27742382011-01-27 09:37:34 -0600[diff] [blame]1788 png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1789
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]1790 file_gamma - the gamma at which the file is
1791 written (PNG_INFO_gAMA)
1792
1793 int_file_gamma - 100,000 times the gamma at which the
1794 file is written
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1795
1796 png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1797
Glenn Randers-Pehrson27742382011-01-27 09:37:34 -0600[diff] [blame]1798 file_srgb_intent - the rendering intent (PNG_INFO_sRGB)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1799 The presence of the sRGB chunk
1800 means that the pixel data is in the
1801 sRGB color space. This chunk also
1802 implies specific values of gAMA and
1803 cHRM.
1804
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1805 png_get_iCCP(png_ptr, info_ptr, &name,
1806 &compression_type, &profile, &proflen);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1807
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1808 name - The profile name.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1809
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1810 compression_type - The compression type; always
1811 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
1812 You may give NULL to this argument to
1813 ignore it.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1814
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1815 profile - International Color Consortium color
1816 profile data. May contain NULs.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1817
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]1818 proflen - length of profile data in bytes.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1819
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1820 png_get_sBIT(png_ptr, info_ptr, &sig_bit);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1821
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1822 sig_bit - the number of significant bits for
1823 (PNG_INFO_sBIT) each of the gray,
1824 red, green, and blue channels,
1825 whichever are appropriate for the
1826 given color type (png_color_16)
1827
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]1828 png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
1829 &num_trans, &trans_color);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1830
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]1831 trans_alpha - array of alpha (transparency)
1832 entries for palette (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1833
Glenn Randers-Pehrsonf3c51e42011-01-15 10:25:25 -0600[diff] [blame]1834 num_trans - number of transparent entries
1835 (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1836
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1837 trans_color - graylevel or color sample values of
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]1838 the single transparent color for
1839 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1840
1841 png_get_hIST(png_ptr, info_ptr, &hist);
1842 (PNG_INFO_hIST)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1843
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1844 hist - histogram of palette (array of
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1845 png_uint_16)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1846
1847 png_get_tIME(png_ptr, info_ptr, &mod_time);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1848
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1849 mod_time - time image was last modified
1850 (PNG_VALID_tIME)
1851
1852 png_get_bKGD(png_ptr, info_ptr, &background);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1853
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1854 background - background color (PNG_VALID_bKGD)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1855 valid 16-bit red, green and blue
1856 values, regardless of color_type
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1857
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1858 num_comments = png_get_text(png_ptr, info_ptr,
1859 &text_ptr, &num_text);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1860
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1861 num_comments - number of comments
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1862
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1863 text_ptr - array of png_text holding image
1864 comments
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1865
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1866 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1867 on "text" PNG_TEXT_COMPRESSION_NONE
1868 PNG_TEXT_COMPRESSION_zTXt
1869 PNG_ITXT_COMPRESSION_NONE
1870 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1871
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1872 text_ptr[i].key - keyword for comment. Must contain
1873 1-79 characters.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1874
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1875 text_ptr[i].text - text comments for current
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]1876 keyword. Can be empty.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1877
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1878 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1879 after decompression, 0 for iTXt
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1880
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1881 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1882 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1883
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1884 text_ptr[i].lang - language of comment (empty
1885 string for unknown).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1886
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]1887 text_ptr[i].lang_key - keyword in UTF-8
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1888 (empty string for unknown).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1889
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]1890 Note that the itxt_length, lang, and lang_key
1891 members of the text_ptr structure only exist
1892 when the library is built with iTXt chunk support.
1893
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1894 num_text - number of comments (same as
1895 num_comments; you can put NULL here
1896 to avoid the duplication)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1897
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1898 Note while png_set_text() will accept text, language,
1899 and translated keywords that can be NULL pointers, the
1900 structure returned by png_get_text will always contain
1901 regular zero-terminated C strings. They might be
1902 empty strings but they will never be NULL pointers.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1903
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1904 num_spalettes = png_get_sPLT(png_ptr, info_ptr,
1905 &palette_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1906
1907 num_spalettes - number of sPLT chunks read.
1908
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1909 palette_ptr - array of palette structures holding
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1910 contents of one or more sPLT chunks
1911 read.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1912
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1913 png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1914 &unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1915
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1916 offset_x - positive offset from the left edge
1917 of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1918
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1919 offset_y - positive offset from the top edge
1920 of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1921
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1922 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
1923
1924 png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1925 &unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1926
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1927 res_x - pixels/unit physical resolution in
1928 x direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1929
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1930 res_y - pixels/unit physical resolution in
1931 x direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1932
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1933 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1934 PNG_RESOLUTION_METER
1935
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1936 png_get_sCAL(png_ptr, info_ptr, &unit, &width,
1937 &height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1938
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1939 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1940
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1941 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1942
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1943 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1944 (width and height are doubles)
1945
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1946 png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
1947 &height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1948
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1949 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1950
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1951 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1952
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1953 height - height of a pixel in physical scale units
1954 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1955
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1956 num_unknown_chunks = png_get_unknown_chunks(png_ptr,
1957 info_ptr, &unknowns)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1958
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1959 unknowns - array of png_unknown_chunk
1960 structures holding unknown chunks
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1961
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1962 unknowns[i].name - name of unknown chunk
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1963
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1964 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1965
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1966 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1967
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1968 unknowns[i].location - position of chunk in file
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1969
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1970 The value of "i" corresponds to the order in which the
1971 chunks were read from the PNG file or inserted with the
1972 png_set_unknown_chunks() function.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1973
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1974The data from the pHYs chunk can be retrieved in several convenient
1975forms:
1976
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1977 res_x = png_get_x_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1978 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1979
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1980 res_y = png_get_y_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1981 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1982
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1983 res_x_and_y = png_get_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1984 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1985
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1986 res_x = png_get_x_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1987 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1988
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1989 res_y = png_get_y_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1990 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1991
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1992 res_x_and_y = png_get_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1993 info_ptr)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1994
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1995 aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1996 info_ptr)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1997
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]1998 Each of these returns 0 [signifying "unknown"] if
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1999 the data is not present or if res_x is 0;
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2000 res_x_and_y is 0 if res_x != res_y
2001
2002 Note that because of the way the resolutions are
2003 stored internally, the inch conversions won't
2004 come out to exactly even number. For example,
2005 72 dpi is stored as 0.28346 pixels/meter, and
2006 when this is retrieved it is 71.9988 dpi, so
2007 be sure to round the returned value appropriately
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2008 if you want to display a reasonable-looking result.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2009
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2010The data from the oFFs chunk can be retrieved in several convenient
2011forms:
2012
2013 x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2014
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2015 y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2016
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2017 x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2018
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2019 y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
2020
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2021 Each of these returns 0 [signifying "unknown" if both
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2022 x and y are 0] if the data is not present or if the
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2023 chunk is present but the unit is the pixel. The
2024 remark about inexact inch conversions applies here
2025 as well, because a value in inches can't always be
2026 converted to microns and back without some loss
2027 of precision.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2028
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2029For more information, see the png_info definition in png.h and the
2030PNG specification for chunk contents. Be careful with trusting
2031rowbytes, as some of the transformations could increase the space
2032needed to hold a row (expand, filler, gray_to_rgb, etc.).
2033See png_read_update_info(), below.
2034
2035A quick word about text_ptr and num_text. PNG stores comments in
2036keyword/text pairs, one pair per chunk, with no limit on the number
2037of text chunks, and a 2^31 byte limit on their size. While there are
2038suggested keywords, there is no requirement to restrict the use to these
2039strings. It is strongly suggested that keywords and text be sensible
2040to humans (that's the point), so don't use abbreviations. Non-printing
2041symbols are not allowed. See the PNG specification for more details.
2042There is also no requirement to have text after the keyword.
2043
2044Keywords should be limited to 79 Latin-1 characters without leading or
2045trailing spaces, but non-consecutive spaces are allowed within the
2046keyword. It is possible to have the same keyword any number of times.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2047The text_ptr is an array of png_text structures, each holding a
2048pointer to a language string, a pointer to a keyword and a pointer to
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2049a text string. The text string, language code, and translated
2050keyword may be empty or NULL pointers. The keyword/text
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2051pairs are put into the array in the order that they are received.
2052However, some or all of the text chunks may be after the image, so, to
2053make sure you have read all the text chunks, don't mess with these
2054until after you read the stuff after the image. This will be
2055mentioned again below in the discussion that goes with png_read_end().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2056
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2057.SS Input transformations
2058
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2059After you've read the header information, you can set up the library
2060to handle any special transformations of the image data. The various
2061ways to transform the data will be described in the order that they
2062should occur. This is important, as some of these change the color
2063type and/or bit depth of the data, and some others only work on
2064certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2065checks to see if it has data that it can do something with, you should
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2066make sure to only enable a transformation if it will be valid for the
2067data. For example, don't swap red and blue on grayscale data.
2068
2069The colors used for the background and transparency values should be
2070supplied in the same format/depth as the current image data. They
2071are stored in the same format/depth as the image data in a bKGD or tRNS
2072chunk, so this is what libpng expects for this data. The colors are
2073transformed to keep in sync with the image data when an application
2074calls the png_read_update_info() routine (see below).
2075
2076Data will be decoded into the supplied row buffers packed into bytes
2077unless the library has been told to transform it into another format.
2078For example, 4 bit/pixel paletted or grayscale data will be returned
20792 pixels/byte with the leftmost pixel in the high-order bits of the
2080byte, unless png_set_packing() is called. 8-bit RGB data will be stored
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2081in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
2082is called to insert filler bytes, either before or after each RGB triplet.
208316-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
2084byte of the color value first, unless png_set_strip_16() is called to
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]2085transform it to regular RGB RGB triplets, or png_set_filler() or
2086png_set_add alpha() is called to insert filler bytes, either before or
2087after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
2088be modified with
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2089png_set_filler(), png_set_add_alpha(), or png_set_strip_16().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2090
2091The following code transforms grayscale images of less than 8 to 8 bits,
2092changes paletted images to RGB, and adds a full alpha channel if there is
2093transparency information in a tRNS chunk. This is most useful on
2094grayscale images with bit depths of 2 or 4 or if there is a multiple-image
2095viewing application that wishes to treat all images in the same way.
2096
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2097 if (color_type == PNG_COLOR_TYPE_PALETTE)
2098 png_set_palette_to_rgb(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2099
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2100 if (png_get_valid(png_ptr, info_ptr,
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2101 PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
2102
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2103 if (color_type == PNG_COLOR_TYPE_GRAY &&
2104 bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
2105
2106The first two functions are actually aliases for png_set_expand(), added
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2107in libpng version 1.0.4, with the function names expanded to improve code
2108readability. In some future version they may actually do different
2109things.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2110
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]2111As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
2112added. It expands the sample depth without changing tRNS to alpha.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2113
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2114As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2115png_set_expand(), however, the resultant channels have 16 bits rather than 8.
2116Use this when the output color or gray channels are made linear to avoid fairly
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2117severe accuracy loss.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2118
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2119 if (bit_depth < 16)
2120 png_set_expand_16(png_ptr);
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]2121
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2122PNG can have files with 16 bits per channel. If you only can handle
21238 bits per channel, this will strip the pixels down to 8 bit.
2124
2125 if (bit_depth == 16)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2126 png_set_strip_16(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2127
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2128If, for some reason, you don't need the alpha channel on an image,
2129and you want to remove it rather than combining it with the background
2130(but the image author certainly had in mind that you *would* combine
2131it with the background, so that's what you should probably do):
2132
2133 if (color_type & PNG_COLOR_MASK_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2134 png_set_strip_alpha(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2135
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2136See below for png_set_background(), which does the correct composition on a
2137single opaque color. This is probably what you should do in all cases rather
2138than use png_set_strip_alpha() - unless you know for sure that it is the wrong
2139thing to do.
2140
2141As of libpng version 1.5.2, almost all useful expansions are supported, the
2142major ommissions are convertion of grayscale to indexed images (which can be
2143done trivially in the application) and convertion of indexed to grayscale (which
2144can be done by a trivial manipulation of the palette.)
2145
2146In the following table, the 01 means grayscale with depth<8, 31 means
2147indexed with depth<8, other numerals represent the color type, "T" means
2148the tRNS chunk is present, A means an alpha channel is present, and O
2149means tRNS or alpha is present but all pixels in the image are opaque.
2150
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2151 FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2152 TO
2153 01 - [G] - - - - - - - - - - - - -
2154 31 [Q] Q [Q] [Q] [Q] Q Q Q Q Q Q [Q] [Q] Q Q
2155 0 1 G + . . G G G G G G B B GB GB
2156 0T lt Gt t + . Gt G G Gt G G Bt Bt GBt GBt
2157 0O lt Gt t . + Gt Gt G Gt Gt G Bt Bt GBt GBt
2158 2 C P C C C + . . C - - CB CB B B
2159 2T Ct - Ct C C t + t - - - CBt CBt Bt Bt
2160 2O Ct - Ct C C t t + - - - CBt CBt Bt Bt
2161 3 [Q] p [Q] [Q] [Q] Q Q Q + . . [Q] [Q] Q Q
2162 3T [Qt] p [Qt][Q] [Q] Qt Qt Qt t + t [Qt][Qt] Qt Qt
2163 3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
2164 4A lA G A T T GA GT GT GA GT GT + BA G GBA
2165 4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
2166 6A CA PA CA C C A T tT PA P P C CBA + BA
2167 6O CA PBA CA C C A tT T PA P P CBA C BA +
2168
2169Within the matrix,
2170 "+" identifies entries where 'from' and 'to' are the same.
2171 "-" means the transformation is not supported.
2172 "." means nothing is necessary (a tRNS chunk can just be ignored).
2173 "t" means the transformation is obtained by png_set_tRNS.
2174 "A" means the transformation is obtained by png_set_add_alpha().
2175 "X" means the transformation is obtained by png_set_expand().
2176 "1" means the transformation is obtained by
2177 png_set_expand_gray_1_2_4_to_8() (and by png_set_expand() if there
2178 is no transparency in the original or the final format).
2179 "C" means the transformation is obtained by png_set_gray_to_rgb().
2180 "G" means the transformation is obtained by png_set_rgb_to_gray() or
2181 png_set_rgb_to_Y().
2182 "P" means the transformation is obtained by
2183 png_set_expand_palette_to_rgb().
2184 "p" means the transformation is obtained by png_set_packing().
2185 "Q" means the transformation is obtained by png_set_quantize().
2186 "T" means the transformation is obtained by png_set_tRNS_to_alpha().
2187 "B" means the transformation is obtained by png_set_background(), or
2188 png_strip_alpha().
John Bowler63d059a2011-02-12 09:03:44 -0600[diff] [blame]2189
2190When an entry has multiple transforms listed all are required to cause the
2191right overall transformation. When two transforms are separated by a comma
2192either will do the job. When transforms are enclosed in [] the transform should
2193do the job but this is currently unimplemented - a different format will result
2194if the suggested transformations are used.
2195
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2196In PNG files, the alpha channel in an image
2197is the level of opacity. If you need the alpha channel in an image to
2198be the level of transparency instead of opacity, you can invert the
2199alpha channel (or the tRNS chunk data) after it's read, so that 0 is
2200fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
2201images) is fully transparent, with
2202
2203 png_set_invert_alpha(png_ptr);
2204
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2205PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
2206they can, resulting in, for example, 8 pixels per byte for 1 bit
2207files. This code expands to 1 pixel per byte without changing the
2208values of the pixels:
2209
2210 if (bit_depth < 8)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2211 png_set_packing(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2212
2213PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
2214stored in a PNG image have been "scaled" or "shifted" up to the next
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2215higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
2216to 8 bits/sample in the range [0, 255]). However, it is also possible
2217to convert the PNG pixel data back to the original bit depth of the
2218image. This call reduces the pixels back down to the original bit depth:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2219
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]2220 png_color_8p sig_bit;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2221
2222 if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2223 png_set_shift(png_ptr, sig_bit);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2224
2225PNG files store 3-color pixels in red, green, blue order. This code
2226changes the storage of the pixels to blue, green, red:
2227
2228 if (color_type == PNG_COLOR_TYPE_RGB ||
2229 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2230 png_set_bgr(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2231
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]2232PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
2233into 4 or 8 bytes for windowing systems that need them in this format:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2234
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]2235 if (color_type == PNG_COLOR_TYPE_RGB)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2236 png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2237
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]2238where "filler" is the 8 or 16-bit number to fill with, and the location is
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2239either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
2240you want the filler before the RGB or after. This transformation
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]2241does not affect images that already have full alpha channels. To add an
2242opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
2243will generate RGBA pixels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2244
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2245Note that png_set_filler() does not change the color type. If you want
2246to do that, you can add a true alpha channel with
2247
2248 if (color_type == PNG_COLOR_TYPE_RGB ||
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2249 color_type == PNG_COLOR_TYPE_GRAY)
2250 png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2251
2252where "filler" contains the alpha value to assign to each pixel.
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]2253This function was added in libpng-1.2.7.
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]2254
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2255If you are reading an image with an alpha channel, and you need the
2256data as ARGB instead of the normal PNG format RGBA:
2257
2258 if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2259 png_set_swap_alpha(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2260
2261For some uses, you may want a grayscale image to be represented as
2262RGB. This code will do that conversion:
2263
2264 if (color_type == PNG_COLOR_TYPE_GRAY ||
2265 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2266 png_set_gray_to_rgb(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2267
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2268Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2269with alpha.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2270
2271 if (color_type == PNG_COLOR_TYPE_RGB ||
2272 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2273 png_set_rgb_to_gray_fixed(png_ptr, error_action,
2274 int red_weight, int green_weight);
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2275
2276 error_action = 1: silently do the conversion
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2277
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2278 error_action = 2: issue a warning if the original
2279 image has any pixel where
2280 red != green or red != blue
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2281
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2282 error_action = 3: issue an error and abort the
2283 conversion if the original
2284 image has any pixel where
2285 red != green or red != blue
2286
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2287 red_weight: weight of red component times 100000
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2288
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2289 green_weight: weight of green component times 100000
2290 If either weight is negative, default
2291 weights (21268, 71514) are used.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2292
2293If you have set error_action = 1 or 2, you can
2294later check whether the image really was gray, after processing
2295the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
2296It will return a png_byte that is zero if the image was gray or
22971 if there were any non-gray pixels. bKGD and sBIT data
2298will be silently converted to grayscale, using the green channel
2299data, regardless of the error_action setting.
2300
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2301With red_weight+green_weight<=100000,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2302the normalized graylevel is computed:
2303
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2304 int rw = red_weight * 65536;
2305 int gw = green_weight * 65536;
2306 int bw = 65536 - (rw + gw);
2307 gray = (rw*red + gw*green + bw*blue)/65536;
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2308
2309The default values approximate those recommended in the Charles
2310Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]2311Copyright (c) 1998-01-04 Charles Poynton <poynton at inforamp.net>
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2312
2313 Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
2314
Glenn Randers-Pehrson9962b842011-01-24 00:12:14 -0600[diff] [blame]2315Libpng approximates this with integers scaled by 32768:
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2316
Glenn Randers-Pehrson9962b842011-01-24 00:12:14 -0600[diff] [blame]2317 Y = (6968 * R + 23434 * G + 2366 * B)/32768
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2318
2319The calculation is done in a linear colorspace, if the image gamma
Glenn Randers-Pehrson9962b842011-01-24 00:12:14 -0600[diff] [blame]2320can be determined.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2321
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]2322If you have a grayscale and you are using png_set_expand_gray_1_2_4_to_8(),
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]2323png_set_expand(), or png_set_gray_to_rgb to change to truecolor or to
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2324a higher bit-depth, you must either supply the background color as a gray
2325value at the original file bit-depth (need_expand = 1) or else supply the
2326background color as an RGB triplet at the final, expanded bit depth
2327(need_expand = 0). Similarly, if you are reading a paletted image, you
2328must either supply the background color as a palette index (need_expand = 1)
2329or as an RGB triplet that may or may not be in the palette (need_expand = 0).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2330
2331 png_color_16 my_background;
2332 png_color_16p image_background;
2333
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2334 if (png_get_bKGD(png_ptr, info_ptr, &image_background))
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2335 png_set_background(png_ptr, image_background,
2336 PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2337 else
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2338 png_set_background(png_ptr, &my_background,
2339 PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2340
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2341The png_set_background() function tells libpng to composite images
2342with alpha or simple transparency against the supplied background
2343color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
2344you may use this color, or supply another color more suitable for
2345the current display (e.g., the background color from a web page). You
2346need to tell libpng whether the color is in the gamma space of the
2347display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
2348(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
2349that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
2350know why anyone would use this, but it's here).
2351
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2352To properly display PNG images on any kind of system, the application needs
2353to know what the display gamma is. Ideally, the user will know this, and
2354the application will allow them to set it. One method of allowing the user
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]2355to set the display gamma separately for each system is to check for a
2356SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
2357correctly set.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2358
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]2359Note that display_gamma is the overall gamma correction required to produce
2360pleasing results, which depends on the lighting conditions in the surrounding
2361environment. In a dim or brightly lit room, no compensation other than
2362the physical gamma exponent of the monitor is needed, while in a dark room
2363a slightly smaller exponent is better.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2364
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2365 double gamma, screen_gamma;
2366
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2367 if (/* We have a user-defined screen
2368 gamma value */)
2369 {
2370 screen_gamma = user_defined_screen_gamma;
2371 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2372
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2373 /* One way that applications can share the same
2374 screen gamma value */
2375 else if ((gamma_str = getenv("SCREEN_GAMMA"))
2376 != NULL)
2377 {
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2378 screen_gamma = (double)atof(gamma_str);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2379 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2380
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2381 /* If we don't have another value */
2382 else
2383 {
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2384 screen_gamma = 2.2; /* A good guess for a
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2385 PC monitor in a bright office or a dim room */
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2386
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2387 screen_gamma = 2.0; /* A good guess for a
2388 PC monitor in a dark room */
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2389
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2390 screen_gamma = 1.7 or 1.0; /* A good
2391 guess for Mac systems */
2392 }
2393
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]2394The functions png_set_gamma() and its fixed point equivalent
2395png_set_gamma_fixed() handle gamma transformations of the data.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2396Pass both the file gamma and the current screen_gamma. If the file does
2397not have a gamma value, you can pass one anyway if you have an idea what
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2398it is (usually 0.45455 is a good guess for GIF images on PCs). Note
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2399that file gammas are inverted from screen gammas. See the discussions
2400on gamma in the PNG specification for an excellent description of what
2401gamma is, and why all applications should support it. It is strongly
2402recommended that PNG viewers support gamma correction.
2403
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]2404 if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
2405 png_set_gamma(png_ptr, screen_gamma, file_gamma);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2406
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2407 else
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2408 png_set_gamma(png_ptr, screen_gamma, 0.45455);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2409
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2410If you need to reduce an RGB file to a paletted file, or if a paletted
2411file has more entries then will fit on your screen, png_set_quantize()
Glenn Randers-Pehrson862cb202010-04-16 22:12:51 -0500[diff] [blame]2412will do that. Note that this is a simple match quantization that merely
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2413finds the closest color available. This should work fairly well with
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2414optimized palettes, but fairly badly with linear color cubes. If you
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2415pass a palette that is larger then maximum_colors, the file will
2416reduce the number of colors in the palette so it will fit into
2417maximum_colors. If there is a histogram, it will use it to make
2418more intelligent choices when reducing the palette. If there is no
2419histogram, it may not do as good a job.
2420
2421 if (color_type & PNG_COLOR_MASK_COLOR)
2422 {
2423 if (png_get_valid(png_ptr, info_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2424 PNG_INFO_PLTE))
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2425 {
2426 png_uint_16p histogram = NULL;
2427
2428 png_get_hIST(png_ptr, info_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2429 &histogram);
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2430 png_set_quantize(png_ptr, palette, num_palette,
2431 max_screen_colors, histogram, 1);
2432 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2433
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]2434 else
2435 {
2436 png_color std_color_cube[MAX_SCREEN_COLORS] =
2437 { ... colors ... };
2438
2439 png_set_quantize(png_ptr, std_color_cube,
2440 MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
2441 NULL,0);
2442 }
2443 }
2444
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2445PNG files describe monochrome as black being zero and white being one.
2446The following code will reverse this (make black be one and white be
2447zero):
2448
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]2449 if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
2450 png_set_invert_mono(png_ptr);
2451
2452This function can also be used to invert grayscale and gray-alpha images:
2453
2454 if (color_type == PNG_COLOR_TYPE_GRAY ||
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2455 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2456 png_set_invert_mono(png_ptr);
2457
2458PNG files store 16 bit pixels in network byte order (big-endian,
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2459ie. most significant bits first). This code changes the storage to the
2460other way (little-endian, i.e. least significant bits first, the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2461way PCs store them):
2462
2463 if (bit_depth == 16)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2464 png_set_swap(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2465
2466If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
2467need to change the order the pixels are packed into bytes, you can use:
2468
2469 if (bit_depth < 8)
2470 png_set_packswap(png_ptr);
2471
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2472Finally, you can write your own transformation function if none of
2473the existing ones meets your needs. This is done by setting a callback
2474with
2475
2476 png_set_read_user_transform_fn(png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2477 read_transform_fn);
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2478
2479You must supply the function
2480
Glenn Randers-Pehrson93215672011-02-13 19:42:19 -0600[diff] [blame]2481 void read_transform_fn(png_structp png_ptr, png_row_infop
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2482 row_info, png_bytep data)
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2483
2484See pngtest.c for a working example. Your function will be called
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]2485after all of the other transformations have been processed. Take care with
2486interlaced images if you do the interlace yourself - the width of the row is the
2487width in 'row_info', not the overall image width.
2488
2489If supported libpng provides two information routines that you can use to find
2490where you are in processing the image:
2491
2492 png_get_current_pass_number(png_structp png_ptr);
2493 png_get_current_row_number(png_structp png_ptr);
2494
2495Don't try using these outside a transform callback - firstly they are only
2496supported if user transforms are supported, secondly they may well return
2497unexpected results unless the row is actually being processed at the moment they
2498are called.
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2499
John Bowlercd113452011-02-16 06:15:13 -0600[diff] [blame]2500With interlaced
2501images the value returned is the row in the input sub-image image. Use
2502PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
2503find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
2504
2505The discussion of interlace handling above contains more information on how to
2506use these values.
2507
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2508You can also set up a pointer to a user structure for use by your
2509callback function, and you can inform libpng that your transform
2510function will change the number of channels or bit depth with the
2511function
2512
2513 png_set_user_transform_info(png_ptr, user_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2514 user_depth, user_channels);
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2515
2516The user's application, not libpng, is responsible for allocating and
2517freeing any memory required for the user structure.
2518
2519You can retrieve the pointer via the function
2520png_get_user_transform_ptr(). For example:
2521
2522 voidp read_user_transform_ptr =
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2523 png_get_user_transform_ptr(png_ptr);
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2524
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2525The last thing to handle is interlacing; this is covered in detail below,
2526but you must call the function here if you want libpng to handle expansion
2527of the interlaced image.
2528
2529 number_of_passes = png_set_interlace_handling(png_ptr);
2530
2531After setting the transformations, libpng can update your png_info
2532structure to reflect any transformations you've requested with this
2533call. This is most useful to update the info structure's rowbytes
2534field so you can use it to allocate your image memory. This function
2535will also update your palette with the correct screen_gamma and
2536background if these have been given with the calls above.
2537
2538 png_read_update_info(png_ptr, info_ptr);
2539
2540After you call png_read_update_info(), you can allocate any
2541memory you need to hold the image. The row data is simply
2542raw byte data for all forms of images. As the actual allocation
2543varies among applications, no example will be given. If you
2544are allocating one large chunk, you will need to build an
2545array of pointers to each row, as it will be needed for some
2546of the functions below.
2547
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2548Remember: Before you call png_read_update_info(), the png_get_
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]2549functions return the values corresponding to the original PNG image.
2550After you call png_read_update_info the values refer to the image
2551that libpng will output. Consequently you must call all the png_set_
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2552functions before you call png_read_update_info(). This is particularly
2553important for png_set_interlace_handling() - if you are going to call
2554png_read_update_info() you must call png_set_interlace_handling() before
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]2555it unless you want to receive interlaced output.
2556
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2557.SS Reading image data
2558
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2559After you've allocated memory, you can read the image data.
2560The simplest way to do this is in one function call. If you are
2561allocating enough memory to hold the whole image, you can just
2562call png_read_image() and libpng will read in all the image data
2563and put it in the memory area supplied. You will need to pass in
2564an array of pointers to each row.
2565
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]2566This function automatically handles interlacing, so you don't
2567need to call png_set_interlace_handling() (unless you call
2568png_read_update_info()) or call this function multiple times, or any
2569of that other stuff necessary with png_read_rows().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2570
2571 png_read_image(png_ptr, row_pointers);
2572
2573where row_pointers is:
2574
2575 png_bytep row_pointers[height];
2576
2577You can point to void or char or whatever you use for pixels.
2578
2579If you don't want to read in the whole image at once, you can
2580use png_read_rows() instead. If there is no interlacing (check
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2581interlace_type == PNG_INTERLACE_NONE), this is simple:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2582
2583 png_read_rows(png_ptr, row_pointers, NULL,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2584 number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2585
2586where row_pointers is the same as in the png_read_image() call.
2587
2588If you are doing this just one row at a time, you can do this with
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2589a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2590
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2591 png_bytep row_pointer = row;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2592 png_read_row(png_ptr, row_pointer, NULL);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2593
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2594If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
2595get somewhat harder. The only current (PNG Specification version 1.2)
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2596interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
2597a somewhat complicated 2D interlace scheme, known as Adam7, that
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2598breaks down an image into seven smaller images of varying size, based
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2599on an 8x8 grid. This number is defined (from libpng 1.5) as
2600PNG_INTERLACE_ADAM7_PASSES in png.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2601
2602libpng can fill out those images or it can give them to you "as is".
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2603It is almost always better to have libpng handle the interlacing for you.
2604If you want the images filled out, there are two ways to do that. The one
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2605mentioned in the PNG specification is to expand each pixel to cover
2606those pixels that have not been read yet (the "rectangle" method).
2607This results in a blocky image for the first pass, which gradually
2608smooths out as more pixels are read. The other method is the "sparkle"
2609method, where pixels are drawn only in their final locations, with the
2610rest of the image remaining whatever colors they were initialized to
2611before the start of the read. The first method usually looks better,
2612but tends to be slower, as there are more pixels to put in the rows.
2613
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2614If, as is likely, you want libpng to expand the images, call this before
2615calling png_start_read_image() or png_read_update_info():
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2616
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2617 if (interlace_type == PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2618 number_of_passes
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2619 = png_set_interlace_handling(png_ptr);
2620
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2621This will return the number of passes needed. Currently, this is seven,
2622but may change if another interlace type is added. This function can be
2623called even if the file is not interlaced, where it will return one pass.
2624You then need to read the whole image 'number_of_passes' times. Each time
2625will distribute the pixels from the current pass to the correct place in
2626the output image, so you need to supply the same rows to png_read_rows in
2627each pass.
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]2628
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2629If you are not going to display the image after each pass, but are
2630going to wait until the entire image is read in, use the sparkle
2631effect. This effect is faster and the end result of either method
2632is exactly the same. If you are planning on displaying the image
2633after each pass, the "rectangle" effect is generally considered the
2634better looking one.
2635
2636If you only want the "sparkle" effect, just call png_read_rows() as
2637normal, with the third parameter NULL. Make sure you make pass over
2638the image number_of_passes times, and you don't change the data in the
2639rows between calls. You can change the locations of the data, just
2640not the data. Each pass only writes the pixels appropriate for that
2641pass, and assumes the data from previous passes is still valid.
2642
2643 png_read_rows(png_ptr, row_pointers, NULL,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2644 number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2645
2646If you only want the first effect (the rectangles), do the same as
2647before except pass the row buffer in the third parameter, and leave
2648the second parameter NULL.
2649
2650 png_read_rows(png_ptr, NULL, row_pointers,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2651 number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2652
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2653If you don't want libpng to handle the interlacing details, just call
2654png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
2655Each of the images is a valid image by itself, however you will almost
2656certainly need to distribute the pixels from each sub-image to the
2657correct place. This is where everything gets very tricky.
2658
2659If you want to retrieve the separate images you must pass the correct
2660number of rows to each successive call of png_read_rows(). The calculation
2661gets pretty complicated for small images, where some sub-images may
2662not even exist because either their width or height ends up zero.
2663libpng provides two macros to help you in 1.5 and later versions:
2664
2665 png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
2666 png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
2667
2668Respectively these tell you the width and height of the sub-image
2669corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
2670this can be confusing because the specification refers to the same passes
2671as 1 to 7! Be careful, you must check both the width and height before
2672calling png_read_rows() and not call it for that pass if either is zero.
2673
2674You can, of course, read each sub-image row by row. If you want to
2675produce optimal code to make a pixel-by-pixel transformation of an
2676interlaced image this is the best approach; read each row of each pass,
2677transform it, and write it out to a new interlaced image.
2678
2679If you want to de-interlace the image yourself libpng provides further
2680macros to help that tell you where to place the pixels in the output image.
2681Because the interlacing scheme is rectangular - sub-image pixels are always
2682arranged on a rectangular grid - all you need to know for each pass is the
2683starting column and row in the output image of the first pixel plus the
2684spacing between each pixel. As of libpng 1.5 there are four macros to
2685retrieve this information:
2686
2687 png_uint_32 x = PNG_PASS_START_COL(pass);
2688 png_uint_32 y = PNG_PASS_START_ROW(pass);
2689 png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
2690 png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
2691
2692These allow you to write the obvious loop:
2693
2694 png_uint_32 input_y = 0;
2695 png_uint_32 output_y = PNG_PASS_START_ROW(pass);
2696
2697 while (output_y < output_image_height)
2698 {
2699 png_uint_32 input_x = 0;
2700 png_uint_32 output_x = PNG_PASS_START_COL(pass);
2701
2702 while (output_x < output_image_width)
2703 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2704 image[output_y][output_x] =
2705 subimage[pass][input_y][input_x++];
2706
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2707 output_x += xStep;
2708 }
2709
2710 ++input_y;
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2711 output_y += yStep;
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2712 }
2713
2714Notice that the steps between successive output rows and columns are
2715returned as shifts. This is possible because the pixels in the subimages
2716are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
2717image. In practice you may need to directly calculate the output coordinate
2718given an input coordinate. libpng provides two further macros for this
2719purpose:
2720
2721 png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
2722 png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
2723
2724Finally a pair of macros are provided to tell you if a particular image
2725row or column appears in a given pass:
2726
2727 int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
2728 int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
2729
2730Bear in mind that you will probably also need to check the width and height
2731of the pass in addition to the above to be sure the pass even exists!
2732
2733With any luck you are convinced by now that you don't want to do your own
2734interlace handling. In reality normally the only good reason for doing this
2735is if you are processing PNG files on a pixel-by-pixel basis and don't want
2736to load the whole file into memory when it is interlaced.
2737
2738libpng includes a test program, pngvalid, that illustrates reading and
2739writing of interlaced images. If you can't get interlacing to work in your
2740code and don't want to leave it to libpng (the recommended approach) see
2741how pngvalid.c does it.
2742
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2743.SS Finishing a sequential read
2744
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]2745After you are finished reading the image through the
2746low-level interface, you can finish reading the file. If you are
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2747interested in comments or time, which may be stored either before or
2748after the image data, you should pass the separate png_info struct if
2749you want to keep the comments from before and after the image
2750separate. If you are not interested, you can pass NULL.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2751
2752 png_read_end(png_ptr, end_info);
2753
2754When you are done, you can free all memory allocated by libpng like this:
2755
2756 png_destroy_read_struct(&png_ptr, &info_ptr,
2757 &end_info);
2758
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2759It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2760point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2761
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2762 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2763
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2764 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2765 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2766 more of
2767 PNG_FREE_PLTE, PNG_FREE_TRNS,
2768 PNG_FREE_HIST, PNG_FREE_ICCP,
2769 PNG_FREE_PCAL, PNG_FREE_ROWS,
2770 PNG_FREE_SCAL, PNG_FREE_SPLT,
2771 PNG_FREE_TEXT, PNG_FREE_UNKN,
2772 or simply PNG_FREE_ALL
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2773
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2774 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2775 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2776
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2777This function may be safely called when the relevant storage has
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]2778already been freed, or has not yet been allocated, or was allocated
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2779by the user and not by libpng, and will in those cases do nothing.
2780The "seq" parameter is ignored if only one item of the selected data
2781type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
2782are allowed for the data type identified in the mask, such as text or
2783sPLT, only the n'th item in the structure is freed, where n is "seq".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2784
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2785The default behavior is only to free data that was allocated internally
2786by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2787or so that it will free data that was allocated by the user with png_malloc()
2788or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2789
2790 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2791
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2792 freer - one of
2793 PNG_DESTROY_WILL_FREE_DATA
2794 PNG_SET_WILL_FREE_DATA
2795 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2796
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2797 mask - which data elements are affected
2798 same choices as in png_free_data()
2799
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2800This function only affects data that has already been allocated.
2801You can call this function after reading the PNG data but before calling
2802any png_set_*() functions, to control whether the user or the png_set_*()
2803function is responsible for freeing any existing data that might be present,
2804and again after the png_set_*() functions to control whether the user
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2805or png_destroy_*() is supposed to free the data. When the user assumes
2806responsibility for libpng-allocated data, the application must use
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2807png_free() to free it, and when the user transfers responsibility to libpng
2808for data that the user has allocated, the user must have used png_malloc()
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]2809or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2810
2811If you allocated your row_pointers in a single block, as suggested above in
2812the description of the high level read interface, you must not transfer
2813responsibility for freeing it to the png_set_rows or png_read_destroy function,
2814because they would also try to free the individual row_pointers[i].
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2815
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2816If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
2817separately, do not transfer responsibility for freeing text_ptr to libpng,
2818because when libpng fills a png_text structure it combines these members with
2819the key member, and png_free_data() will free only text_ptr.key. Similarly,
2820if you transfer responsibility for free'ing text_ptr from libpng to your
2821application, your application must not separately free those members.
2822
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2823The png_free_data() function will turn off the "valid" flag for anything
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2824it frees. If you need to turn the flag off for a chunk that was freed by
2825your application instead of by libpng, you can use
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2826
2827 png_set_invalid(png_ptr, info_ptr, mask);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2828
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2829 mask - identifies the chunks to be made invalid,
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2830 containing the bitwise OR of one or
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]2831 more of
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2832 PNG_INFO_gAMA, PNG_INFO_sBIT,
2833 PNG_INFO_cHRM, PNG_INFO_PLTE,
2834 PNG_INFO_tRNS, PNG_INFO_bKGD,
2835 PNG_INFO_hIST, PNG_INFO_pHYs,
2836 PNG_INFO_oFFs, PNG_INFO_tIME,
2837 PNG_INFO_pCAL, PNG_INFO_sRGB,
2838 PNG_INFO_iCCP, PNG_INFO_sPLT,
2839 PNG_INFO_sCAL, PNG_INFO_IDAT
2840
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2841For a more compact example of reading a PNG image, see the file example.c.
2842
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2843.SS Reading PNG files progressively
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2844
2845The progressive reader is slightly different then the non-progressive
2846reader. Instead of calling png_read_info(), png_read_rows(), and
2847png_read_end(), you make one call to png_process_data(), which calls
2848callbacks when it has the info, a row, or the end of the image. You
2849set up these callbacks with png_set_progressive_read_fn(). You don't
2850have to worry about the input/output functions of libpng, as you are
2851giving the library the data directly in png_process_data(). I will
2852assume that you have read the section on reading PNG files above,
2853so I will only highlight the differences (although I will show
2854all of the code).
2855
2856png_structp png_ptr;
2857png_infop info_ptr;
2858
2859 /* An example code fragment of how you would
2860 initialize the progressive reader in your
2861 application. */
2862 int
2863 initialize_png_reader()
2864 {
2865 png_ptr = png_create_read_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2866 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2867 user_error_fn, user_warning_fn);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2868
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2869 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2870 return (ERROR);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2871
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2872 info_ptr = png_create_info_struct(png_ptr);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2873
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2874 if (!info_ptr)
2875 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2876 png_destroy_read_struct(&png_ptr,
2877 (png_infopp)NULL, (png_infopp)NULL);
2878 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2879 }
2880
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2881 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2882 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2883 png_destroy_read_struct(&png_ptr, &info_ptr,
2884 (png_infopp)NULL);
2885 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2886 }
2887
2888 /* This one's new. You can provide functions
2889 to be called when the header info is valid,
2890 when each row is completed, and when the image
2891 is finished. If you aren't using all functions,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2892 you can specify NULL parameters. Even when all
2893 three functions are NULL, you need to call
2894 png_set_progressive_read_fn(). You can use
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2895 any struct as the user_ptr (cast to a void pointer
2896 for the function call), and retrieve the pointer
2897 from inside the callbacks using the function
2898
2899 png_get_progressive_ptr(png_ptr);
2900
2901 which will return a void pointer, which you have
2902 to cast appropriately.
2903 */
2904 png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
2905 info_callback, row_callback, end_callback);
2906
2907 return 0;
2908 }
2909
2910 /* A code fragment that you call as you receive blocks
2911 of data */
2912 int
2913 process_data(png_bytep buffer, png_uint_32 length)
2914 {
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2915 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2916 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2917 png_destroy_read_struct(&png_ptr, &info_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2918 (png_infopp)NULL);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]2919 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2920 }
2921
2922 /* This one's new also. Simply give it a chunk
2923 of data from the file stream (in order, of
2924 course). On machines with segmented memory
2925 models machines, don't give it any more than
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2926 64K. The library seems to run fine with sizes
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2927 of 4K. Although you can give it much less if
2928 necessary (I assume you can give it chunks of
2929 1 byte, I haven't tried less then 256 bytes
2930 yet). When this function returns, you may
2931 want to display any rows that were generated
2932 in the row callback if you don't already do
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2933 so there.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2934 */
2935 png_process_data(png_ptr, info_ptr, buffer, length);
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]2936
2937 /* At this point you can call png_process_data_skip if
2938 you want to handle data the library will skip yourself;
2939 it simply returns the number of bytes to skip (and stops
2940 libpng skipping that number of bytes on the next
2941 png_process_data call).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2942 return 0;
2943 }
2944
2945 /* This function is called (as set by
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2946 png_set_progressive_read_fn() above) when enough data
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2947 has been supplied so all of the header has been
2948 read.
2949 */
2950 void
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2951 info_callback(png_structp png_ptr, png_infop info)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2952 {
2953 /* Do any setup here, including setting any of
2954 the transformations mentioned in the Reading
2955 PNG files section. For now, you _must_ call
2956 either png_start_read_image() or
2957 png_read_update_info() after all the
2958 transformations are set (even if you don't set
2959 any). You may start getting rows before
2960 png_process_data() returns, so this is your
2961 last chance to prepare for that.
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2962
2963 This is where you turn on interlace handling,
2964 assuming you don't want to do it yourself.
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]2965
2966 If you need to you can stop the processing of
2967 your original input data at this point by calling
2968 png_process_data_pause. This returns the number
2969 of unprocessed bytes from the last png_process_data
2970 call - it is up to you to ensure that the next call
2971 sees these bytes again. If you don't want to bother
2972 with this you can get libpng to cache the unread
2973 bytes by setting the 'save' parameter (see png.h) but
2974 then libpng will have to copy the data internally.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2975 */
2976 }
2977
2978 /* This function is called when each row of image
2979 data is complete */
2980 void
2981 row_callback(png_structp png_ptr, png_bytep new_row,
Glenn Randers-Pehrsone68f5a32001-05-14 09:20:53 -0500[diff] [blame]2982 png_uint_32 row_num, int pass)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2983 {
2984 /* If the image is interlaced, and you turned
2985 on the interlace handler, this function will
2986 be called for every row in every pass. Some
2987 of these rows will not be changed from the
2988 previous pass. When the row is not changed,
2989 the new_row variable will be NULL. The rows
2990 and passes are called in order, so you don't
2991 really need the row_num and pass, but I'm
2992 supplying them because it may make your life
2993 easier.
2994
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]2995 If you did not turn on interlace handling then
2996 the callback is called for each row of each
2997 sub-image when the image is interlaced. In this
2998 case 'row_num' is the row in the sub-image, not
2999 the row in the output image as it is in all other
3000 cases.
3001
3002 For the non-NULL rows of interlaced images when
3003 you have switched on libpng interlace handling,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3004 you must call png_progressive_combine_row()
3005 passing in the row and the old row. You can
3006 call this function for NULL rows (it will just
3007 return) and for non-interlaced images (it just
3008 does the memcpy for you) if it will make the
3009 code easier. Thus, you can just do this for
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3010 all cases if you switch on interlace handling;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3011 */
3012
3013 png_progressive_combine_row(png_ptr, old_row,
3014 new_row);
3015
3016 /* where old_row is what was displayed for
Glenn Randers-Pehrson345bc271998-06-14 14:43:31 -0500[diff] [blame]3017 previously for the row. Note that the first
3018 pass (pass == 0, really) will completely cover
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3019 the old row, so the rows do not have to be
3020 initialized. After the first pass (and only
3021 for interlaced images), you will have to pass
3022 the current row, and the function will combine
3023 the old row and the new row.
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]3024
3025 You can also call png_process_data_pause in this
3026 callback - see above.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3027 */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3028 }
3029
3030 void
3031 end_callback(png_structp png_ptr, png_infop info)
3032 {
3033 /* This function is called after the whole image
3034 has been read, including any chunks after the
3035 image (up to and including the IEND). You
3036 will usually have the same info chunk as you
3037 had in the header, although some data may have
3038 been added to the comments and time fields.
3039
3040 Most people won't do much here, perhaps setting
3041 a flag that marks the image as finished.
3042 */
3043 }
3044
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3045
3046
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3047.SH IV. Writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3048
3049Much of this is very similar to reading. However, everything of
3050importance is repeated here, so you won't have to constantly look
3051back up in the reading section to understand writing.
3052
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3053.SS Setup
3054
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3055You will want to do the I/O initialization before you get into libpng,
3056so if it doesn't work, you don't have anything to undo. If you are not
3057using the standard I/O functions, you will need to replace them with
3058custom writing functions. See the discussion under Customizing libpng.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3059
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3060 FILE *fp = fopen(file_name, "wb");
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3061
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3062 if (!fp)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3063 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3064
3065Next, png_struct and png_info need to be allocated and initialized.
3066As these can be both relatively large, you may not want to store these
3067on the stack, unless you have stack space to spare. Of course, you
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3068will want to check if they return NULL. If you are also reading,
3069you won't want to name your read structure and your write structure
3070both "png_ptr"; you can call them anything you like, such as
3071"read_ptr" and "write_ptr". Look at pngtest.c, for example.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3072
3073 png_structp png_ptr = png_create_write_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3074 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3075 user_error_fn, user_warning_fn);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3076
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3077 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3078 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3079
3080 png_infop info_ptr = png_create_info_struct(png_ptr);
3081 if (!info_ptr)
3082 {
3083 png_destroy_write_struct(&png_ptr,
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3084 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3085 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3086 }
3087
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3088If you want to use your own memory allocation routines,
3089define PNG_USER_MEM_SUPPORTED and use
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3090png_create_write_struct_2() instead of png_create_write_struct():
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3091
3092 png_structp png_ptr = png_create_write_struct_2
3093 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
3094 user_error_fn, user_warning_fn, (png_voidp)
3095 user_mem_ptr, user_malloc_fn, user_free_fn);
3096
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3097After you have these structures, you will need to set up the
3098error handling. When libpng encounters an error, it expects to
3099longjmp() back to your routine. Therefore, you will need to call
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3100setjmp() and pass the png_jmpbuf(png_ptr). If you
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3101write the file from different routines, you will need to update
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3102the png_jmpbuf(png_ptr) every time you enter a new routine that will
3103call a png_*() function. See your documentation of setjmp/longjmp
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3104for your compiler for more information on setjmp/longjmp. See
3105the discussion on libpng error handling in the Customizing Libpng
3106section below for more information on the libpng error handling.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3107
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3108 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3109 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3110 png_destroy_write_struct(&png_ptr, &info_ptr);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]3111 fclose(fp);
3112 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3113 }
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3114 ...
3115 return;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3116
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3117If you would rather avoid the complexity of setjmp/longjmp issues,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]3118you can compile libpng with PNG_NO_SETJMP, in which case
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3119errors will result in a call to PNG_ABORT() which defaults to abort().
3120
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]3121You can #define PNG_ABORT() to a function that does something
3122more useful than abort(), as long as your function does not
3123return.
3124
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3125Now you need to set up the output code. The default for libpng is to
3126use the C function fwrite(). If you use this, you will need to pass a
3127valid FILE * in the function png_init_io(). Be sure that the file is
3128opened in binary mode. Again, if you wish to handle writing data in
3129another way, see the discussion on libpng I/O handling in the Customizing
3130Libpng section below.
3131
3132 png_init_io(png_ptr, fp);
3133
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]3134If you are embedding your PNG into a datastream such as MNG, and don't
3135want libpng to write the 8-byte signature, or if you have already
3136written the signature in your application, use
3137
3138 png_set_sig_bytes(png_ptr, 8);
3139
3140to inform libpng that it should not write a signature.
3141
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3142.SS Write callbacks
3143
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3144At this point, you can set up a callback function that will be
3145called after each row has been written, which you can use to control
3146a progress meter or the like. It's demonstrated in pngtest.c.
3147You must supply a function
3148
Glenn Randers-Pehrson81ce8892011-01-24 08:04:37 -0600[diff] [blame]3149 void write_row_callback(png_structp png_ptr, png_uint_32 row,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3150 int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3151 {
3152 /* put your code here */
3153 }
3154
3155(You can give it another name that you like instead of "write_row_callback")
3156
3157To inform libpng about your function, use
3158
3159 png_set_write_status_fn(png_ptr, write_row_callback);
3160
John Bowler59010e52011-02-16 06:16:31 -0600[diff] [blame]3161When this function is called the row has already been completely processed and
3162it has also been written out. The 'row' and 'pass' refer to the next row to be
3163handled. For the
3164non-interlaced case the row that was just handled is simply one less than the
3165passed in row number, and pass will always be 0. For the interlaced case the
3166same applies unless the row value is 0, in which case the row just handled was
3167the last one from one of the preceding passes. Because interlacing may skip a
3168pass you cannot be sure that the preceding pass is just 'pass-1', if you really
3169need to know what the last pass is record (row,pass) from the callback and use
3170the last recorded value each time.
3171
3172As with the user transform you can find the output row using the
3173PNG_ROW_FROM_PASS_ROW macro.
3174
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3175You now have the option of modifying how the compression library will
3176run. The following functions are mainly for testing, but may be useful
3177in some cases, like if you need to write PNG files extremely fast and
3178are willing to give up some compression, or if you want to get the
3179maximum possible compression at the expense of slower writing. If you
3180have no special needs in this area, let the library do what it wants by
3181not calling this function at all, as it has been tuned to deliver a good
3182speed/compression ratio. The second parameter to png_set_filter() is
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3183the filter method, for which the only valid values are 0 (as of the
3184July 1999 PNG specification, version 1.2) or 64 (if you are writing
3185a PNG datastream that is to be embedded in a MNG datastream). The third
3186parameter is a flag that indicates which filter type(s) are to be tested
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3187for each scanline. See the PNG specification for details on the specific
3188filter types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3189
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3190
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3191 /* turn on or off filtering, and/or choose
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3192 specific filters. You can use either a single
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3193 PNG_FILTER_VALUE_NAME or the bitwise OR of one
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3194 or more PNG_FILTER_NAME masks.
3195 */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3196 png_set_filter(png_ptr, 0,
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3197 PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
3198 PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
3199 PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3200 PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3201 PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
3202 PNG_ALL_FILTERS);
3203
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3204If an application wants to start and stop using particular filters during
3205compression, it should start out with all of the filters (to ensure that
3206the previous row of pixels will be stored in case it's needed later),
3207and then add and remove them after the start of compression.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3208
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3209If you are writing a PNG datastream that is to be embedded in a MNG
3210datastream, the second parameter can be either 0 or 64.
3211
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3212The png_set_compression_*() functions interface to the zlib compression
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3213library, and should mostly be ignored unless you really know what you are
3214doing. The only generally useful call is png_set_compression_level()
3215which changes how much time zlib spends on trying to compress the image
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3216data. See the Compression Library (zlib.h and algorithm.txt, distributed
3217with zlib) for details on the compression levels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3218
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame]3219 #include zlib.h
3220
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3221 /* set the zlib compression level */
3222 png_set_compression_level(png_ptr,
3223 Z_BEST_COMPRESSION);
3224
3225 /* set other zlib parameters */
3226 png_set_compression_mem_level(png_ptr, 8);
3227 png_set_compression_strategy(png_ptr,
3228 Z_DEFAULT_STRATEGY);
3229 png_set_compression_window_bits(png_ptr, 15);
3230 png_set_compression_method(png_ptr, 8);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3231 png_set_compression_buffer_size(png_ptr, 8192)
3232
3233extern PNG_EXPORT(void,png_set_zbuf_size)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3234
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3235.SS Setting the contents of info for output
3236
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3237You now need to fill in the png_info structure with all the data you
3238wish to write before the actual image. Note that the only thing you
3239are allowed to write after the image is the text chunks and the time
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3240chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3241the latest PNG specification for more information on that. If you
3242wish to write them before the image, fill them in now, and flag that
3243data as being valid. If you want to wait until after the data, don't
3244fill them until png_write_end(). For all the fields in png_info and
3245their data types, see png.h. For explanations of what the fields
3246contain, see the PNG specification.
3247
3248Some of the more important parts of the png_info are:
3249
3250 png_set_IHDR(png_ptr, info_ptr, width, height,
3251 bit_depth, color_type, interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3252 compression_type, filter_method)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3253
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3254 width - holds the width of the image
3255 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3256
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3257 height - holds the height of the image
3258 in pixels (up to 2^31).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3259
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3260 bit_depth - holds the bit depth of one of the
3261 image channels.
3262 (valid values are 1, 2, 4, 8, 16
3263 and depend also on the
3264 color_type. See also significant
3265 bits (sBIT) below).
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3266
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3267 color_type - describes which color/alpha
3268 channels are present.
3269 PNG_COLOR_TYPE_GRAY
3270 (bit depths 1, 2, 4, 8, 16)
3271 PNG_COLOR_TYPE_GRAY_ALPHA
3272 (bit depths 8, 16)
3273 PNG_COLOR_TYPE_PALETTE
3274 (bit depths 1, 2, 4, 8)
3275 PNG_COLOR_TYPE_RGB
3276 (bit_depths 8, 16)
3277 PNG_COLOR_TYPE_RGB_ALPHA
3278 (bit_depths 8, 16)
3279
3280 PNG_COLOR_MASK_PALETTE
3281 PNG_COLOR_MASK_COLOR
3282 PNG_COLOR_MASK_ALPHA
3283
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3284 interlace_type - PNG_INTERLACE_NONE or
3285 PNG_INTERLACE_ADAM7
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3286
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3287 compression_type - (must be
3288 PNG_COMPRESSION_TYPE_DEFAULT)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3289
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3290 filter_method - (must be PNG_FILTER_TYPE_DEFAULT
3291 or, if you are writing a PNG to
3292 be embedded in a MNG datastream,
3293 can also be
3294 PNG_INTRAPIXEL_DIFFERENCING)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3295
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3296If you call png_set_IHDR(), the call must appear before any of the
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]3297other png_set_*() functions, because they might require access to some of
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3298the IHDR settings. The remaining png_set_*() functions can be called
3299in any order.
3300
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]3301If you wish, you can reset the compression_type, interlace_type, or
3302filter_method later by calling png_set_IHDR() again; if you do this, the
3303width, height, bit_depth, and color_type must be the same in each call.
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3304
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3305 png_set_PLTE(png_ptr, info_ptr, palette,
3306 num_palette);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3307
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3308 palette - the palette for the file
3309 (array of png_color)
3310 num_palette - number of entries in the palette
3311
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]3312 png_set_gAMA(png_ptr, info_ptr, file_gamma);
3313 png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3314
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]3315 file_gamma - the gamma at which the image was
3316 created (PNG_INFO_gAMA)
3317
3318 int_file_gamma - 100,000 times the gamma at which
3319 the image was created
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3320
3321 png_set_sRGB(png_ptr, info_ptr, srgb_intent);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3322
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3323 srgb_intent - the rendering intent
3324 (PNG_INFO_sRGB) The presence of
3325 the sRGB chunk means that the pixel
3326 data is in the sRGB color space.
3327 This chunk also implies specific
3328 values of gAMA and cHRM. Rendering
3329 intent is the CSS-1 property that
3330 has been defined by the International
3331 Color Consortium
3332 (http://www.color.org).
3333 It can be one of
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3334 PNG_sRGB_INTENT_SATURATION,
3335 PNG_sRGB_INTENT_PERCEPTUAL,
3336 PNG_sRGB_INTENT_ABSOLUTE, or
3337 PNG_sRGB_INTENT_RELATIVE.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3338
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3339
3340 png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
3341 srgb_intent);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3342
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3343 srgb_intent - the rendering intent
3344 (PNG_INFO_sRGB) The presence of the
3345 sRGB chunk means that the pixel
3346 data is in the sRGB color space.
3347 This function also causes gAMA and
3348 cHRM chunks with the specific values
3349 that are consistent with sRGB to be
3350 written.
3351
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3352 png_set_iCCP(png_ptr, info_ptr, name, compression_type,
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3353 profile, proflen);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3354
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3355 name - The profile name.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3356
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3357 compression_type - The compression type; always
3358 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
3359 You may give NULL to this argument to
3360 ignore it.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3361
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3362 profile - International Color Consortium color
3363 profile data. May contain NULs.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3364
Glenn Randers-Pehrson4a5a1ec2011-01-15 11:43:28 -0600[diff] [blame]3365 proflen - length of profile data in bytes.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3366
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3367 png_set_sBIT(png_ptr, info_ptr, sig_bit);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3368
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3369 sig_bit - the number of significant bits for
3370 (PNG_INFO_sBIT) each of the gray, red,
3371 green, and blue channels, whichever are
3372 appropriate for the given color type
3373 (png_color_16)
3374
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]3375 png_set_tRNS(png_ptr, info_ptr, trans_alpha,
3376 num_trans, trans_color);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3377
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]3378 trans_alpha - array of alpha (transparency)
3379 entries for palette (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3380
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]3381 trans_color - graylevel or color sample values
3382 (in order red, green, blue) of the
3383 single transparent color for
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]3384 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3385
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3386 num_trans - number of transparent entries
3387 (PNG_INFO_tRNS)
3388
3389 png_set_hIST(png_ptr, info_ptr, hist);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3390
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3391 hist - histogram of palette (array of
Glenn Randers-Pehrson8d0bc0f2011-01-25 22:15:58 -0600[diff] [blame]3392 png_uint_16) (PNG_INFO_hIST)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3393
3394 png_set_tIME(png_ptr, info_ptr, mod_time);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3395
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3396 mod_time - time image was last modified
3397 (PNG_VALID_tIME)
3398
3399 png_set_bKGD(png_ptr, info_ptr, background);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3400
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3401 background - background color (PNG_VALID_bKGD)
3402
3403 png_set_text(png_ptr, info_ptr, text_ptr, num_text);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3404
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3405 text_ptr - array of png_text holding image
3406 comments
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3407
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3408 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3409 on "text" PNG_TEXT_COMPRESSION_NONE
3410 PNG_TEXT_COMPRESSION_zTXt
3411 PNG_ITXT_COMPRESSION_NONE
3412 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3413 text_ptr[i].key - keyword for comment. Must contain
3414 1-79 characters.
3415 text_ptr[i].text - text comments for current
3416 keyword. Can be NULL or empty.
3417 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3418 after decompression, 0 for iTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3419 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3420 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3421 text_ptr[i].lang - language of comment (NULL or
3422 empty for unknown).
3423 text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
3424 or empty for unknown).
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]3425 Note that the itxt_length, lang, and lang_key
3426 members of the text_ptr structure only exist
3427 when the library is built with iTXt chunk support.
3428
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3429 num_text - number of comments
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3430
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3431 png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
3432 num_spalettes);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3433
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3434 palette_ptr - array of png_sPLT_struct structures
3435 to be added to the list of palettes
3436 in the info structure.
3437 num_spalettes - number of palette structures to be
3438 added.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3439
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3440 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
3441 unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3442
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3443 offset_x - positive offset from the left
3444 edge of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3445
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3446 offset_y - positive offset from the top
3447 edge of the screen
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3448
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3449 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
3450
3451 png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
3452 unit_type);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3453
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3454 res_x - pixels/unit physical resolution
3455 in x direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3456
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3457 res_y - pixels/unit physical resolution
3458 in y direction
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3459
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3460 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3461 PNG_RESOLUTION_METER
3462
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3463 png_set_sCAL(png_ptr, info_ptr, unit, width, height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3464
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3465 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3466
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3467 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3468
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3469 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3470 (width and height are doubles)
3471
3472 png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3473
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3474 unit - physical scale units (an integer)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3475
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3476 width - width of a pixel in physical scale units
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3477
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3478 height - height of a pixel in physical scale units
3479 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3480
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3481 png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
3482 num_unknowns)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3483
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3484 unknowns - array of png_unknown_chunk
3485 structures holding unknown chunks
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3486 unknowns[i].name - name of unknown chunk
3487 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]3488 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3489 unknowns[i].location - position to write chunk in file
3490 0: do not write chunk
3491 PNG_HAVE_IHDR: before PLTE
3492 PNG_HAVE_PLTE: before IDAT
3493 PNG_AFTER_IDAT: after IDAT
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3494
3495The "location" member is set automatically according to
3496what part of the output file has already been written.
3497You can change its value after calling png_set_unknown_chunks()
3498as demonstrated in pngtest.c. Within each of the "locations",
3499the chunks are sequenced according to their position in the
3500structure (that is, the value of "i", which is the order in which
3501the chunk was either read from the input file or defined with
3502png_set_unknown_chunks).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3503
3504A quick word about text and num_text. text is an array of png_text
3505structures. num_text is the number of valid structures in the array.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3506Each png_text structure holds a language code, a keyword, a text value,
3507and a compression type.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3508
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3509The compression types have the same valid numbers as the compression
3510types of the image data. Currently, the only valid number is zero.
3511However, you can store text either compressed or uncompressed, unlike
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3512images, which always have to be compressed. So if you don't want the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3513text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3514Because tEXt and zTXt chunks don't have a language field, if you
3515specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
3516any language code or translated keyword will not be written out.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3517
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3518Until text gets around 1000 bytes, it is not worth compressing it.
3519After the text has been written out to the file, the compression type
3520is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
3521so that it isn't written out again at the end (in case you are calling
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3522png_write_end() with the same struct).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3523
3524The keywords that are given in the PNG Specification are:
3525
3526 Title Short (one line) title or
3527 caption for image
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3528
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3529 Author Name of image's creator
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3530
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3531 Description Description of image (possibly long)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3532
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3533 Copyright Copyright notice
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3534
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3535 Creation Time Time of original image creation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3536 (usually RFC 1123 format, see below)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3537
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3538 Software Software used to create the image
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3539
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3540 Disclaimer Legal disclaimer
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3541
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3542 Warning Warning of nature of content
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3543
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3544 Source Device used to create the image
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3545
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3546 Comment Miscellaneous comment; conversion
3547 from other image format
3548
3549The keyword-text pairs work like this. Keywords should be short
3550simple descriptions of what the comment is about. Some typical
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3551keywords are found in the PNG specification, as is some recommendations
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3552on keywords. You can repeat keywords in a file. You can even write
3553some text before the image and some after. For example, you may want
3554to put a description of the image before the image, but leave the
3555disclaimer until after, so viewers working over modem connections
3556don't have to wait for the disclaimer to go over the modem before
3557they start seeing the image. Finally, keywords should be full
3558words, not abbreviations. Keywords and text are in the ISO 8859-1
3559(Latin-1) character set (a superset of regular ASCII) and can not
3560contain NUL characters, and should not contain control or other
3561unprintable characters. To make the comments widely readable, stick
3562with basic ASCII, and avoid machine specific character set extensions
3563like the IBM-PC character set. The keyword must be present, but
3564you can leave off the text string on non-compressed pairs.
3565Compressed pairs must have a text string, as only the text string
3566is compressed anyway, so the compression would be meaningless.
3567
3568PNG supports modification time via the png_time structure. Two
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3569conversion routines are provided, png_convert_from_time_t() for
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3570time_t and png_convert_from_struct_tm() for struct tm. The
3571time_t routine uses gmtime(). You don't have to use either of
3572these, but if you wish to fill in the png_time structure directly,
3573you should provide the time in universal time (GMT) if possible
3574instead of your local time. Note that the year number is the full
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3575year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3576that months start with 1.
3577
3578If you want to store the time of the original image creation, you should
3579use a plain tEXt chunk with the "Creation Time" keyword. This is
3580necessary because the "creation time" of a PNG image is somewhat vague,
3581depending on whether you mean the PNG file, the time the image was
3582created in a non-PNG format, a still photo from which the image was
3583scanned, or possibly the subject matter itself. In order to facilitate
3584machine-readable dates, it is recommended that the "Creation Time"
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3585tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3586although this isn't a requirement. Unlike the tIME chunk, the
3587"Creation Time" tEXt chunk is not expected to be automatically changed
3588by the software. To facilitate the use of RFC 1123 dates, a function
3589png_convert_to_rfc1123(png_timep) is provided to convert from PNG
3590time to an RFC 1123 format string.
3591
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3592.SS Writing unknown chunks
3593
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3594You can use the png_set_unknown_chunks function to queue up chunks
3595for writing. You give it a chunk name, raw data, and a size; that's
3596all there is to it. The chunks will be written by the next following
3597png_write_info_before_PLTE, png_write_info, or png_write_end function.
3598Any chunks previously read into the info structure's unknown-chunk
3599list will also be written out in a sequence that satisfies the PNG
3600specification's ordering rules.
3601
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3602.SS The high-level write interface
3603
3604At this point there are two ways to proceed; through the high-level
3605write interface, or through a sequence of low-level write operations.
3606You can use the high-level interface if your image data is present
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3607in the info structure. All defined output
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3608transformations are permitted, enabled by the following masks.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3609
3610 PNG_TRANSFORM_IDENTITY No transformation
3611 PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3612 PNG_TRANSFORM_PACKSWAP Change order of packed
3613 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3614 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3615 PNG_TRANSFORM_SHIFT Normalize pixels to the
3616 sBIT depth
3617 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
3618 to BGRA
3619 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
3620 to AG
3621 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
3622 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3623 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson1eb14e92008-12-10 07:14:45 -0600[diff] [blame]3624 PNG_TRANSFORM_STRIP_FILLER Strip out filler
3625 bytes (deprecated).
3626 PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
3627 filler bytes
3628 PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
3629 filler bytes
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3630
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3631If you have valid image data in the info structure (you can use
3632png_set_rows() to put image data in the info structure), simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3633
3634 png_write_png(png_ptr, info_ptr, png_transforms, NULL)
3635
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3636where png_transforms is an integer containing the bitwise OR of some set of
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3637transformation flags. This call is equivalent to png_write_info(),
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3638followed the set of transformations indicated by the transform mask,
3639then png_write_image(), and finally png_write_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3640
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3641(The final parameter of this call is not yet used. Someday it might point
3642to transformation parameters required by some future output transform.)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3643
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]3644You must use png_transforms and not call any png_set_transform() functions
3645when you use png_write_png().
3646
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3647.SS The low-level write interface
3648
3649If you are going the low-level route instead, you are now ready to
3650write all the file information up to the actual image data. You do
3651this with a call to png_write_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3652
3653 png_write_info(png_ptr, info_ptr);
3654
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3655Note that there is one transformation you may need to do before
3656png_write_info(). In PNG files, the alpha channel in an image is the
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3657level of opacity. If your data is supplied as a level of transparency,
3658you can invert the alpha channel before you write it, so that 0 is
3659fully transparent and 255 (in 8-bit or paletted images) or 65535
3660(in 16-bit images) is fully opaque, with
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3661
3662 png_set_invert_alpha(png_ptr);
3663
3664This must appear before png_write_info() instead of later with the
3665other transformations because in the case of paletted images the tRNS
3666chunk data has to be inverted before the tRNS chunk is written. If
3667your image is not a paletted image, the tRNS data (which in such cases
3668represents a single color to be rendered as transparent) won't need to
3669be changed, and you can safely do this transformation after your
3670png_write_info() call.
3671
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3672If you need to write a private chunk that you want to appear before
3673the PLTE chunk when PLTE is present, you can write the PNG info in
3674two steps, and insert code to write your own chunk between them:
3675
3676 png_write_info_before_PLTE(png_ptr, info_ptr);
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3677 png_set_unknown_chunks(png_ptr, info_ptr, ...);
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3678 png_write_info(png_ptr, info_ptr);
3679
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3680After you've written the file information, you can set up the library
3681to handle any special transformations of the image data. The various
3682ways to transform the data will be described in the order that they
3683should occur. This is important, as some of these change the color
3684type and/or bit depth of the data, and some others only work on
3685certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3686checks to see if it has data that it can do something with, you should
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3687make sure to only enable a transformation if it will be valid for the
3688data. For example, don't swap red and blue on grayscale data.
3689
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3690PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]3691the library to strip input data that has 4 or 8 bytes per pixel down
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3692to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
3693bytes per pixel).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3694
3695 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
3696
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3697where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3698PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
3699is stored XRGB or RGBX.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3700
3701PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
3702they can, resulting in, for example, 8 pixels per byte for 1 bit files.
3703If the data is supplied at 1 pixel per byte, use this code, which will
3704correctly pack the pixels into a single byte:
3705
3706 png_set_packing(png_ptr);
3707
3708PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
3709data is of another bit depth, you can write an sBIT chunk into the
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3710file so that decoders can recover the original data if desired.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3711
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3712 /* Set the true bit depth of the image data */
3713 if (color_type & PNG_COLOR_MASK_COLOR)
3714 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3715 sig_bit.red = true_bit_depth;
3716 sig_bit.green = true_bit_depth;
3717 sig_bit.blue = true_bit_depth;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3718 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3719
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3720 else
3721 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3722 sig_bit.gray = true_bit_depth;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3723 }
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3724
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3725 if (color_type & PNG_COLOR_MASK_ALPHA)
3726 {
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3727 sig_bit.alpha = true_bit_depth;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3728 }
3729
3730 png_set_sBIT(png_ptr, info_ptr, &sig_bit);
3731
3732If the data is stored in the row buffer in a bit depth other than
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3733one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3734this will scale the values to appear to be the correct bit depth as
3735is required by PNG.
3736
3737 png_set_shift(png_ptr, &sig_bit);
3738
3739PNG files store 16 bit pixels in network byte order (big-endian,
3740ie. most significant bits first). This code would be used if they are
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3741supplied the other way (little-endian, i.e. least significant bits
3742first, the way PCs store them):
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3743
3744 if (bit_depth > 8)
3745 png_set_swap(png_ptr);
3746
3747If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
3748need to change the order the pixels are packed into bytes, you can use:
3749
3750 if (bit_depth < 8)
3751 png_set_packswap(png_ptr);
3752
3753PNG files store 3 color pixels in red, green, blue order. This code
3754would be used if they are supplied as blue, green, red:
3755
3756 png_set_bgr(png_ptr);
3757
3758PNG files describe monochrome as black being zero and white being
3759one. This code would be used if the pixels are supplied with this reversed
3760(black being one and white being zero):
3761
3762 png_set_invert_mono(png_ptr);
3763
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3764Finally, you can write your own transformation function if none of
3765the existing ones meets your needs. This is done by setting a callback
3766with
3767
3768 png_set_write_user_transform_fn(png_ptr,
3769 write_transform_fn);
3770
3771You must supply the function
3772
Glenn Randers-Pehrson93215672011-02-13 19:42:19 -0600[diff] [blame]3773 void write_transform_fn(png_structp png_ptr, png_row_infop
3774 row_info, png_bytep data)
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3775
3776See pngtest.c for a working example. Your function will be called
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]3777before any of the other transformations are processed. If supported
3778libpng also supplies an information routine that may be called from
3779your callback:
3780
3781 png_get_current_row_number(png_ptr);
John Bowlercd113452011-02-16 06:15:13 -0600[diff] [blame]3782 png_get_current_pass_number(png_ptr);
John Bowlerf19abd62011-01-22 18:29:24 -0600[diff] [blame]3783
John Bowlercd113452011-02-16 06:15:13 -0600[diff] [blame]3784This returns the current row passed to the transform. With interlaced
3785images the value returned is the row in the input sub-image image. Use
3786PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
3787find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
3788
3789The discussion of interlace handling above contains more information on how to
3790use these values.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3791
3792You can also set up a pointer to a user structure for use by your
3793callback function.
3794
3795 png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
3796
3797The user_channels and user_depth parameters of this function are ignored
3798when writing; you can set them to zero as shown.
3799
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3800You can retrieve the pointer via the function png_get_user_transform_ptr().
3801For example:
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3802
3803 voidp write_user_transform_ptr =
3804 png_get_user_transform_ptr(png_ptr);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3805
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3806It is possible to have libpng flush any pending output, either manually,
3807or automatically after a certain number of lines have been written. To
3808flush the output stream a single time call:
3809
3810 png_write_flush(png_ptr);
3811
3812and to have libpng flush the output stream periodically after a certain
3813number of scanlines have been written, call:
3814
3815 png_set_flush(png_ptr, nrows);
3816
3817Note that the distance between rows is from the last time png_write_flush()
3818was called, or the first row of the image if it has never been called.
3819So if you write 50 lines, and then png_set_flush 25, it will flush the
3820output on the next scanline, and every 25 lines thereafter, unless
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3821png_write_flush() is called before 25 more lines have been written.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3822If nrows is too small (less than about 10 lines for a 640 pixel wide
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3823RGB image) the image compression may decrease noticeably (although this
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3824may be acceptable for real-time applications). Infrequent flushing will
3825only degrade the compression performance by a few percent over images
3826that do not use flushing.
3827
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3828.SS Writing the image data
3829
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3830That's it for the transformations. Now you can write the image data.
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3831The simplest way to do this is in one function call. If you have the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3832whole image in memory, you can just call png_write_image() and libpng
3833will write the image. You will need to pass in an array of pointers to
3834each row. This function automatically handles interlacing, so you don't
3835need to call png_set_interlace_handling() or call this function multiple
3836times, or any of that other stuff necessary with png_write_rows().
3837
3838 png_write_image(png_ptr, row_pointers);
3839
3840where row_pointers is:
3841
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3842 png_byte *row_pointers[height];
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3843
3844You can point to void or char or whatever you use for pixels.
3845
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3846If you don't want to write the whole image at once, you can
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3847use png_write_rows() instead. If the file is not interlaced,
3848this is simple:
3849
3850 png_write_rows(png_ptr, row_pointers,
3851 number_of_rows);
3852
3853row_pointers is the same as in the png_write_image() call.
3854
3855If you are just writing one row at a time, you can do this with
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3856a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3857
3858 png_bytep row_pointer = row;
3859
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3860 png_write_row(png_ptr, row_pointer);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3861
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3862When the file is interlaced, things can get a good deal more complicated.
3863The only currently (as of the PNG Specification version 1.2, dated July
38641999) defined interlacing scheme for PNG files is the "Adam7" interlace
3865scheme, that breaks down an image into seven smaller images of varying
3866size. libpng will build these images for you, or you can do them
3867yourself. If you want to build them yourself, see the PNG specification
3868for details of which pixels to write when.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3869
3870If you don't want libpng to handle the interlacing details, just
3871use png_set_interlace_handling() and call png_write_rows() the
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3872correct number of times to write all the sub-images
3873(png_set_interlace_handling() returns the number of sub-images.)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3874
3875If you want libpng to build the sub-images, call this before you start
3876writing any rows:
3877
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3878 number_of_passes = png_set_interlace_handling(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3879
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3880This will return the number of passes needed. Currently, this is seven,
3881but may change if another interlace type is added.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3882
3883Then write the complete image number_of_passes times.
3884
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3885 png_write_rows(png_ptr, row_pointers, number_of_rows);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3886
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]3887Think carefully before you write an interlaced image. Typically code that
3888reads such images reads all the image data into memory, uncompressed, before
3889doing any processing. Only code that can display an image on the fly can
3890take advantage of the interlacing and even then the image has to be exactly
3891the correct size for the output device, because scaling an image requires
3892adjacent pixels and these are not available until all the passes have been
3893read.
3894
3895If you do write an interlaced image you will hardly ever need to handle
3896the interlacing yourself. Call png_set_interlace_handling() and use the
3897approach described above.
3898
3899The only time it is conceivable that you will really need to write an
3900interlaced image pass-by-pass is when you have read one pass by pass and
3901made some pixel-by-pixel transformation to it, as described in the read
3902code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
3903to determine the size of each sub-image in turn and simply write the rows
3904you obtained from the read code.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3905
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3906.SS Finishing a sequential write
3907
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3908After you are finished writing the image, you should finish writing
3909the file. If you are interested in writing comments or time, you should
3910pass an appropriately filled png_info pointer. If you are not interested,
3911you can pass NULL.
3912
3913 png_write_end(png_ptr, info_ptr);
3914
3915When you are done, you can free all memory used by libpng like this:
3916
3917 png_destroy_write_struct(&png_ptr, &info_ptr);
3918
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3919It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3920point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3921
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3922 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3923
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3924 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3925 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3926 more of
3927 PNG_FREE_PLTE, PNG_FREE_TRNS,
3928 PNG_FREE_HIST, PNG_FREE_ICCP,
3929 PNG_FREE_PCAL, PNG_FREE_ROWS,
3930 PNG_FREE_SCAL, PNG_FREE_SPLT,
3931 PNG_FREE_TEXT, PNG_FREE_UNKN,
3932 or simply PNG_FREE_ALL
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3933
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3934 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3935 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3936
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3937This function may be safely called when the relevant storage has
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3938already been freed, or has not yet been allocated, or was allocated
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3939by the user and not by libpng, and will in those cases do nothing.
3940The "seq" parameter is ignored if only one item of the selected data
3941type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
3942are allowed for the data type identified in the mask, such as text or
3943sPLT, only the n'th item in the structure is freed, where n is "seq".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3944
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3945If you allocated data such as a palette that you passed in to libpng
3946with png_set_*, you must not free it until just before the call to
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3947png_destroy_write_struct().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3948
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3949The default behavior is only to free data that was allocated internally
3950by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3951or so that it will free data that was allocated by the user with png_malloc()
3952or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3953
3954 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3955
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3956 freer - one of
3957 PNG_DESTROY_WILL_FREE_DATA
3958 PNG_SET_WILL_FREE_DATA
3959 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3960
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3961 mask - which data elements are affected
3962 same choices as in png_free_data()
3963
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3964For example, to transfer responsibility for some data from a read structure
3965to a write structure, you could use
3966
3967 png_data_freer(read_ptr, read_info_ptr,
3968 PNG_USER_WILL_FREE_DATA,
3969 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]3970
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3971 png_data_freer(write_ptr, write_info_ptr,
3972 PNG_DESTROY_WILL_FREE_DATA,
3973 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
3974
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3975thereby briefly reassigning responsibility for freeing to the user but
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3976immediately afterwards reassigning it once more to the write_destroy
3977function. Having done this, it would then be safe to destroy the read
3978structure and continue to use the PLTE, tRNS, and hIST data in the write
3979structure.
3980
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3981This function only affects data that has already been allocated.
3982You can call this function before calling after the png_set_*() functions
3983to control whether the user or png_destroy_*() is supposed to free the data.
3984When the user assumes responsibility for libpng-allocated data, the
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3985application must use
3986png_free() to free it, and when the user transfers responsibility to libpng
3987for data that the user has allocated, the user must have used png_malloc()
3988or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3989
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3990If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
3991separately, do not transfer responsibility for freeing text_ptr to libpng,
3992because when libpng fills a png_text structure it combines these members with
3993the key member, and png_free_data() will free only text_ptr.key. Similarly,
3994if you transfer responsibility for free'ing text_ptr from libpng to your
3995application, your application must not separately free those members.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3996For a more compact example of writing a PNG image, see the file example.c.
3997
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3998.SH V. Modifying/Customizing libpng:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3999
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4000There are two issues here. The first is changing how libpng does
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4001standard things like memory allocation, input/output, and error handling.
4002The second deals with more complicated things like adding new chunks,
4003adding new transformations, and generally changing how libpng works.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]4004Both of those are compile-time issues; that is, they are generally
4005determined at the time the code is written, and there is rarely a need
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4006to provide the user with a means of changing them.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]4007
4008Memory allocation, input/output, and error handling
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4009
4010All of the memory allocation, input/output, and error handling in libpng
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]4011goes through callbacks that are user-settable. The default routines are
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4012in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]4013these functions, call the appropriate png_set_*_fn() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4014
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4015Memory allocation is done through the functions png_malloc(), png_calloc(),
4016and png_free(). These currently just call the standard C functions.
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]4017png_calloc() calls png_malloc() and then clears the newly
4018allocated memory to zero. There is limited support for certain systems
4019with segmented memory architectures and the types of pointers declared by
4020png.h match this; you will have to use appropriate pointers in your
4021application. Since it is
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4022unlikely that the method of handling memory allocation on a platform
4023will change between applications, these functions must be modified in
4024the library at compile time. If you prefer to use a different method
4025of allocating and freeing data, you can use png_create_read_struct_2() or
4026png_create_write_struct_2() to register your own functions as described
4027above. These functions also provide a void pointer that can be retrieved
4028via
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4029
4030 mem_ptr=png_get_mem_ptr(png_ptr);
4031
4032Your replacement memory functions must have prototypes as follows:
4033
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4034 png_voidp malloc_fn(png_structp png_ptr,
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4035 png_alloc_size_t size);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4036
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4037 void free_fn(png_structp png_ptr, png_voidp ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4038
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4039Your malloc_fn() must return NULL in case of failure. The png_malloc()
4040function will normally call png_error() if it receives a NULL from the
4041system memory allocator or from your replacement malloc_fn().
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]4042
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4043Your free_fn() will never be called with a NULL ptr, since libpng's
4044png_free() checks for NULL before calling free_fn().
4045
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4046Input/Output in libpng is done through png_read() and png_write(),
4047which currently just call fread() and fwrite(). The FILE * is stored in
4048png_struct and is initialized via png_init_io(). If you wish to change
4049the method of I/O, the library supplies callbacks that you can set
4050through the function png_set_read_fn() and png_set_write_fn() at run
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4051time, instead of calling the png_init_io() function. These functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4052also provide a void pointer that can be retrieved via the function
4053png_get_io_ptr(). For example:
4054
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]4055 png_set_read_fn(png_structp read_ptr,
4056 voidp read_io_ptr, png_rw_ptr read_data_fn)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4057
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]4058 png_set_write_fn(png_structp write_ptr,
4059 voidp write_io_ptr, png_rw_ptr write_data_fn,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4060 png_flush_ptr output_flush_fn);
4061
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]4062 voidp read_io_ptr = png_get_io_ptr(read_ptr);
4063 voidp write_io_ptr = png_get_io_ptr(write_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4064
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4065The replacement I/O functions must have prototypes as follows:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4066
4067 void user_read_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]4068 png_bytep data, png_size_t length);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4069
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4070 void user_write_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]4071 png_bytep data, png_size_t length);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4072
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4073 void user_flush_data(png_structp png_ptr);
4074
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]4075The user_read_data() function is responsible for detecting and
4076handling end-of-data errors.
4077
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4078Supplying NULL for the read, write, or flush functions sets them back
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4079to using the default C stream functions, which expect the io_ptr to
4080point to a standard *FILE structure. It is probably a mistake
4081to use NULL for one of write_data_fn and output_flush_fn but not both
4082of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
4083It is an error to read from a write stream, and vice versa.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4084
4085Error handling in libpng is done through png_error() and png_warning().
4086Errors handled through png_error() are fatal, meaning that png_error()
4087should never return to its caller. Currently, this is handled via
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4088setjmp() and longjmp() (unless you have compiled libpng with
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]4089PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
Glenn Randers-Pehrson60988072010-04-13 22:11:06 -0500[diff] [blame]4090but you could change this to do things like exit() if you should wish,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]4091as long as your function does not return.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4092
4093On non-fatal errors, png_warning() is called
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4094to print a warning message, and then control returns to the calling code.
4095By default png_error() and png_warning() print a message on stderr via
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]4096fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
4097(because you don't want the messages) or PNG_NO_STDIO defined (because
4098fprintf() isn't available). If you wish to change the behavior of the error
4099functions, you will need to set up your own message callbacks. These
4100functions are normally supplied at the time that the png_struct is created.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4101It is also possible to redirect errors and warnings to your own replacement
4102functions after png_create_*_struct() has been called by calling:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4103
4104 png_set_error_fn(png_structp png_ptr,
4105 png_voidp error_ptr, png_error_ptr error_fn,
4106 png_error_ptr warning_fn);
4107
4108 png_voidp error_ptr = png_get_error_ptr(png_ptr);
4109
4110If NULL is supplied for either error_fn or warning_fn, then the libpng
4111default function will be used, calling fprintf() and/or longjmp() if a
4112problem is encountered. The replacement error functions should have
4113parameters as follows:
4114
4115 void user_error_fn(png_structp png_ptr,
4116 png_const_charp error_msg);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4117
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4118 void user_warning_fn(png_structp png_ptr,
4119 png_const_charp warning_msg);
4120
4121The motivation behind using setjmp() and longjmp() is the C++ throw and
4122catch exception handling methods. This makes the code much easier to write,
4123as there is no need to check every return code of every function call.
4124However, there are some uncertainties about the status of local variables
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4125after a longjmp, so the user may want to be careful about doing anything
4126after setjmp returns non-zero besides returning itself. Consult your
4127compiler documentation for more details. For an alternative approach, you
4128may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4129
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4130.SS Custom chunks
4131
4132If you need to read or write custom chunks, you may need to get deeper
4133into the libpng code. The library now has mechanisms for storing
4134and writing chunks of unknown type; you can even declare callbacks
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]4135for custom chunks. However, this may not be good enough if the
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4136library code itself needs to know about interactions between your
4137chunk and existing `intrinsic' chunks.
4138
4139If you need to write a new intrinsic chunk, first read the PNG
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4140specification. Acquire a first level of understanding of how it works.
4141Pay particular attention to the sections that describe chunk names,
4142and look at how other chunks were designed, so you can do things
4143similarly. Second, check out the sections of libpng that read and
4144write chunks. Try to find a chunk that is similar to yours and use
4145it as a template. More details can be found in the comments inside
4146the code. It is best to handle unknown chunks in a generic method,
4147via callback functions, instead of by modifying libpng functions.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4148
4149If you wish to write your own transformation for the data, look through
4150the part of the code that does the transformations, and check out some of
4151the simpler ones to get an idea of how they work. Try to find a similar
4152transformation to the one you want to add and copy off of it. More details
4153can be found in the comments inside the code itself.
4154
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4155.SS Configuring for 16 bit platforms
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4156
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4157You will want to look into zconf.h to tell zlib (and thus libpng) that
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4158it cannot allocate more then 64K at a time. Even if you can, the memory
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4159won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4160
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4161.SS Configuring for DOS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4162
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4163For DOS users who only have access to the lower 640K, you will
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4164have to limit zlib's memory usage via a png_set_compression_mem_level()
4165call. See zlib.h or zconf.h in the zlib library for more information.
4166
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4167.SS Configuring for Medium Model
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4168
4169Libpng's support for medium model has been tested on most of the popular
4170compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
4171defined, and FAR gets defined to far in pngconf.h, and you should be
4172all set. Everything in the library (except for zlib's structure) is
4173expecting far data. You must use the typedefs with the p or pp on
4174the end for pointers (or at least look at them and be careful). Make
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4175note that the rows of data are defined as png_bytepp, which is an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4176unsigned char far * far *.
4177
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4178.SS Configuring for gui/windowing platforms:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4179
4180You will need to write new error and warning functions that use the GUI
4181interface, as described previously, and set them to be the error and
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]4182warning functions at the time that png_create_*_struct() is called,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4183in order to have them available during the structure initialization.
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4184They can be changed later via png_set_error_fn(). On some compilers,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4185you may also have to change the memory allocators (png_malloc, etc.).
4186
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4187.SS Configuring for compiler xxx:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4188
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]4189All includes for libpng are in pngconf.h. If you need to add, change
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4190or delete an include, this is the place to do it.
4191The includes that are not needed outside libpng are placed in pngpriv.h,
4192which is only used by the routines inside libpng itself.
4193The files in libpng proper only include pngpriv.h and png.h, which
4194in turn includes pngconf.h.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4195
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4196.SS Configuring zlib:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4197
4198There are special functions to configure the compression. Perhaps the
4199most useful one changes the compression level, which currently uses
4200input compression values in the range 0 - 9. The library normally
4201uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
4202have shown that for a large majority of images, compression values in
4203the range 3-6 compress nearly as well as higher levels, and do so much
4204faster. For online applications it may be desirable to have maximum speed
4205(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
4206specify no compression (Z_NO_COMPRESSION = 0), but this would create
4207files larger than just storing the raw bitmap. You can specify the
4208compression level by calling:
4209
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame]4210 #include zlib.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4211 png_set_compression_level(png_ptr, level);
4212
4213Another useful one is to reduce the memory level used by the library.
4214The memory level defaults to 8, but it can be lowered if you are
4215short on memory (running DOS, for example, where you only have 640K).
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4216Note that the memory level does have an effect on compression; among
4217other things, lower levels will result in sections of incompressible
4218data being emitted in smaller stored blocks, with a correspondingly
4219larger relative overhead of up to 15% in the worst case.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4220
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame]4221 #include zlib.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4222 png_set_compression_mem_level(png_ptr, level);
4223
4224The other functions are for configuring zlib. They are not recommended
4225for normal use and may result in writing an invalid PNG file. See
4226zlib.h for more information on what these mean.
4227
Glenn Randers-Pehrson38734ee2011-03-03 06:23:31 -0600[diff] [blame]4228 #include zlib.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4229 png_set_compression_strategy(png_ptr,
4230 strategy);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4231
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4232 png_set_compression_window_bits(png_ptr,
4233 window_bits);
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4234
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4235 png_set_compression_method(png_ptr, method);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4236 png_set_compression_buffer_size(png_ptr, size);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4237
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4238.SS Controlling row filtering
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4239
4240If you want to control whether libpng uses filtering or not, which
4241filters are used, and how it goes about picking row filters, you
4242can call one of these functions. The selection and configuration
4243of row filters can have a significant impact on the size and
4244encoding speed and a somewhat lesser impact on the decoding speed
4245of an image. Filtering is enabled by default for RGB and grayscale
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4246images (with and without alpha), but not for paletted images nor
4247for any images with bit depths less than 8 bits/pixel.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4248
4249The 'method' parameter sets the main filtering method, which is
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4250currently only '0' in the PNG 1.2 specification. The 'filters'
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4251parameter sets which filter(s), if any, should be used for each
4252scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
4253to turn filtering on and off, respectively.
4254
4255Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
4256PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]4257ORed together with '|' to specify one or more filters to use.
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4258These filters are described in more detail in the PNG specification.
4259If you intend to change the filter type during the course of writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4260the image, you should start with flags set for all of the filters
4261you intend to use so that libpng can initialize its internal
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4262structures appropriately for all of the filter types. (Note that this
4263means the first row must always be adaptively filtered, because libpng
4264currently does not allocate the filter buffers until png_write_row()
4265is called for the first time.)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4266
4267 filters = PNG_FILTER_NONE | PNG_FILTER_SUB
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4268 PNG_FILTER_UP | PNG_FILTER_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4269 PNG_FILTER_PAETH | PNG_ALL_FILTERS;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4270
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4271 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
4272 filters);
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4273 The second parameter can also be
4274 PNG_INTRAPIXEL_DIFFERENCING if you are
4275 writing a PNG to be embedded in a MNG
4276 datastream. This parameter must be the
4277 same as the value of filter_method used
4278 in png_set_IHDR().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4279
4280It is also possible to influence how libpng chooses from among the
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4281available filters. This is done in one or both of two ways - by
4282telling it how important it is to keep the same filter for successive
4283rows, and by telling it the relative computational costs of the filters.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4284
4285 double weights[3] = {1.5, 1.3, 1.1},
4286 costs[PNG_FILTER_VALUE_LAST] =
4287 {1.0, 1.3, 1.3, 1.5, 1.7};
4288
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4289 png_set_filter_heuristics(png_ptr,
4290 PNG_FILTER_HEURISTIC_WEIGHTED, 3,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4291 weights, costs);
4292
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4293The weights are multiplying factors that indicate to libpng that the
4294row filter should be the same for successive rows unless another row filter
4295is that many times better than the previous filter. In the above example,
4296if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4297"sum of absolute differences" 1.5 x 1.3 times higher than other filters
4298and still be chosen, while the NONE filter could have a sum 1.1 times
4299higher than other filters and still be chosen. Unspecified weights are
4300taken to be 1.0, and the specified weights should probably be declining
4301like those above in order to emphasize recent filters over older filters.
4302
4303The filter costs specify for each filter type a relative decoding cost
4304to be considered when selecting row filters. This means that filters
4305with higher costs are less likely to be chosen over filters with lower
4306costs, unless their "sum of absolute differences" is that much smaller.
4307The costs do not necessarily reflect the exact computational speeds of
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4308the various filters, since this would unduly influence the final image
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4309size.
4310
4311Note that the numbers above were invented purely for this example and
4312are given only to help explain the function usage. Little testing has
4313been done to find optimum values for either the costs or the weights.
4314
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4315.SS Removing unwanted object code
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4316
4317There are a bunch of #define's in pngconf.h that control what parts of
4318libpng are compiled. All the defines end in _SUPPORTED. If you are
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]4319never going to use a capability, you can change the #define to #undef
4320before recompiling libpng and save yourself code and data space, or
4321you can turn off individual capabilities with defines that begin with
4322PNG_NO_.
4323
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4324In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
4325
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]4326You can also turn all of the transforms and ancillary chunk capabilities
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]4327off en masse with compiler directives that define
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]4328PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
4329or all four,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4330along with directives to turn on any of the capabilities that you do
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4331want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra
4332transformations but still leave the library fully capable of reading
4333and writing PNG files with all known public chunks. Use of the
4334PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
4335that is incapable of reading or writing ancillary chunks. If you are
4336not using the progressive reading capability, you can turn that off
4337with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
4338capability, which you'll still have).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4339
4340All the reading and writing specific code are in separate files, so the
4341linker should only grab the files it needs. However, if you want to
4342make sure, or if you are building a stand alone library, all the
4343reading files start with pngr and all the writing files start with
4344pngw. The files that don't match either (like png.c, pngtrans.c, etc.)
4345are used for both reading and writing, and always need to be included.
4346The progressive reader is in pngpread.c
4347
4348If you are creating or distributing a dynamically linked library (a .so
4349or DLL file), you should not remove or disable any parts of the library,
4350as this will cause applications linked with different versions of the
4351library to fail if they call functions not available in your library.
4352The size of the library itself should not be an issue, because only
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4353those sections that are actually used will be loaded into memory.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4354
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]4355.SS Requesting debug printout
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4356
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4357The macro definition PNG_DEBUG can be used to request debugging
4358printout. Set it to an integer value in the range 0 to 3. Higher
4359numbers result in increasing amounts of debugging information. The
4360information is printed to the "stderr" file, unless another file
4361name is specified in the PNG_DEBUG_FILE macro definition.
4362
4363When PNG_DEBUG > 0, the following functions (macros) become available:
4364
4365 png_debug(level, message)
4366 png_debug1(level, message, p1)
4367 png_debug2(level, message, p1, p2)
4368
4369in which "level" is compared to PNG_DEBUG to decide whether to print
4370the message, "message" is the formatted string to be printed,
4371and p1 and p2 are parameters that are to be embedded in the string
4372according to printf-style formatting directives. For example,
4373
4374 png_debug1(2, "foo=%d\n", foo);
4375
4376is expanded to
4377
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4378 if (PNG_DEBUG > 2)
4379 fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4380
4381When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
4382can still use PNG_DEBUG to control your own debugging:
4383
4384 #ifdef PNG_DEBUG
4385 fprintf(stderr, ...
4386 #endif
4387
4388When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
4389having level = 0 will be printed. There aren't any such statements in
4390this version of libpng, but if you insert some they will be printed.
4391
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]4392.SH VI. MNG support
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]4393
4394The MNG specification (available at http://www.libpng.org/pub/mng) allows
4395certain extensions to PNG for PNG images that are embedded in MNG datastreams.
4396Libpng can support some of these extensions. To enable them, use the
4397png_permit_mng_features() function:
4398
4399 feature_set = png_permit_mng_features(png_ptr, mask)
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4400
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]4401 mask is a png_uint_32 containing the bitwise OR of the
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]4402 features you want to enable. These include
4403 PNG_FLAG_MNG_EMPTY_PLTE
4404 PNG_FLAG_MNG_FILTER_64
4405 PNG_ALL_MNG_FEATURES
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4406
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]4407 feature_set is a png_uint_32 that is the bitwise AND of
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]4408 your mask with the set of MNG features that is
4409 supported by the version of libpng that you are using.
4410
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]4411It is an error to use this function when reading or writing a standalone
4412PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
Glenn Randers-Pehrsonf05f8032000-12-23 14:27:39 -0600[diff] [blame]4413in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
4414and the MHDR and MEND chunks. Libpng does not provide support for these
4415or any other MNG chunks; your application must provide its own support for
4416them. You may wish to consider using libmng (available at
4417http://www.libmng.com) instead.
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]4418
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]4419.SH VII. Changes to Libpng from version 0.88
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4420
4421It should be noted that versions of libpng later than 0.96 are not
4422distributed by the original libpng author, Guy Schalnat, nor by
4423Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
4424distributed versions 0.89 through 0.96, but rather by another member
4425of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
4426still alive and well, but they have moved on to other things.
4427
4428The old libpng functions png_read_init(), png_write_init(),
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]4429png_info_init(), png_read_destroy(), and png_write_destroy() have been
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]4430moved to PNG_INTERNAL in version 0.95 to discourage their use. These
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4431functions will be removed from libpng version 1.4.0.
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]4432
4433The preferred method of creating and initializing the libpng structures is
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4434via the png_create_read_struct(), png_create_write_struct(), and
4435png_create_info_struct() because they isolate the size of the structures
4436from the application, allow version error checking, and also allow the
4437use of custom error handling routines during the initialization, which
4438the old functions do not. The functions png_read_destroy() and
4439png_write_destroy() do not actually free the memory that libpng
4440allocated for these structs, but just reset the data structures, so they
4441can be used instead of png_destroy_read_struct() and
4442png_destroy_write_struct() if you feel there is too much system overhead
4443allocating and freeing the png_struct for each image read.
4444
4445Setting the error callbacks via png_set_message_fn() before
4446png_read_init() as was suggested in libpng-0.88 is no longer supported
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]4447because this caused applications that do not use custom error functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4448to fail if the png_ptr was not initialized to zero. It is still possible
4449to set the error callbacks AFTER png_read_init(), or to change them with
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]4450png_set_error_fn(), which is essentially the same function, but with a new
4451name to force compilation errors with applications that try to use the old
4452method.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4453
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]4454Starting with version 1.0.7, you can find out which version of the library
4455you are using at run-time:
4456
4457 png_uint_32 libpng_vn = png_access_version_number();
4458
4459The number libpng_vn is constructed from the major version, minor
4460version with leading zero, and release number with leading zero,
4461(e.g., libpng_vn for version 1.0.7 is 10007).
4462
4463You can also check which version of png.h you used when compiling your
4464application:
4465
4466 png_uint_32 application_vn = PNG_LIBPNG_VER;
4467
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4468.SH VIII. Changes to Libpng from version 1.0.x to 1.2.x
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4469
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4470Support for user memory management was enabled by default. To
4471accomplish this, the functions png_create_read_struct_2(),
4472png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
4473png_malloc_default(), and png_free_default() were added.
4474
Glenn Randers-Pehrsond6ea40a2009-11-02 07:32:00 -0600[diff] [blame]4475Support for the iTXt chunk has been enabled by default as of
4476version 1.2.41.
4477
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4478Support for certain MNG features was enabled.
4479
4480Support for numbered error messages was added. However, we never got
4481around to actually numbering the error messages. The function
4482png_set_strip_error_numbers() was added (Note: the prototype for this
4483function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
4484builds of libpng-1.2.15. It was restored in libpng-1.2.36).
4485
4486The png_malloc_warn() function was added at libpng-1.2.3. This issues
4487a png_warning and returns NULL instead of aborting when it fails to
4488acquire the requested memory allocation.
4489
4490Support for setting user limits on image width and height was enabled
4491by default. The functions png_set_user_limits(), png_get_user_width_max(),
4492and png_get_user_height_max() were added at libpng-1.2.6.
4493
4494The png_set_add_alpha() function was added at libpng-1.2.7.
4495
4496The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
4497Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
4498tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
4499deprecated.
4500
4501A number of macro definitions in support of runtime selection of
4502assembler code features (especially Intel MMX code support) were
4503added at libpng-1.2.0:
4504
4505 PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
4506 PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
4507 PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
4508 PNG_ASM_FLAG_MMX_READ_INTERLACE
4509 PNG_ASM_FLAG_MMX_READ_FILTER_SUB
4510 PNG_ASM_FLAG_MMX_READ_FILTER_UP
4511 PNG_ASM_FLAG_MMX_READ_FILTER_AVG
4512 PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
4513 PNG_ASM_FLAGS_INITIALIZED
4514 PNG_MMX_READ_FLAGS
4515 PNG_MMX_FLAGS
4516 PNG_MMX_WRITE_FLAGS
4517 PNG_MMX_FLAGS
4518
4519We added the following functions in support of runtime
4520selection of assembler code features:
4521
4522 png_get_mmx_flagmask()
4523 png_set_mmx_thresholds()
4524 png_get_asm_flags()
4525 png_get_mmx_bitdepth_threshold()
4526 png_get_mmx_rowbytes_threshold()
4527 png_set_asm_flags()
4528
4529We replaced all of these functions with simple stubs in libpng-1.2.20,
4530when the Intel assembler code was removed due to a licensing issue.
4531
Glenn Randers-Pehrson3d893a02009-08-31 13:32:46 -0500[diff] [blame]4532These macros are deprecated:
4533
4534 PNG_READ_TRANSFORMS_NOT_SUPPORTED
4535 PNG_PROGRESSIVE_READ_NOT_SUPPORTED
4536 PNG_NO_SEQUENTIAL_READ_SUPPORTED
4537 PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
4538 PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
4539 PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
4540
4541They have been replaced, respectively, by:
4542
4543 PNG_NO_READ_TRANSFORMS
4544 PNG_NO_PROGRESSIVE_READ
4545 PNG_NO_SEQUENTIAL_READ
4546 PNG_NO_WRITE_TRANSFORMS
4547 PNG_NO_READ_ANCILLARY_CHUNKS
4548 PNG_NO_WRITE_ANCILLARY_CHUNKS
4549
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4550PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
4551deprecated since libpng-1.0.16 and libpng-1.2.6.
4552
4553The function
4554 png_check_sig(sig, num)
4555was replaced with
4556 !png_sig_cmp(sig, 0, num)
4557It has been deprecated since libpng-0.90.
4558
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4559The function
4560 png_set_gray_1_2_4_to_8()
4561which also expands tRNS to alpha was replaced with
4562 png_set_expand_gray_1_2_4_to_8()
4563which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4564
Glenn Randers-Pehrsond740c842009-11-04 19:01:54 -0600[diff] [blame]4565.SH IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
4566
4567Private libpng prototypes and macro definitions were moved from
4568png.h and pngconf.h into a new pngpriv.h header file.
4569
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4570Functions png_set_benign_errors(), png_benign_error(), and
4571png_chunk_benign_error() were added.
4572
4573Support for setting the maximum amount of memory that the application
4574will allocate for reading chunks was added, as a security measure.
4575The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
4576were added to the library.
4577
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4578We implemented support for I/O states by adding png_ptr member io_state
4579and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4580
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4581We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
4582input transforms.
4583
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4584Checking for and reporting of errors in the IHDR chunk is more thorough.
4585
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4586Support for global arrays was removed, to improve thread safety.
4587
4588Some obsolete/deprecated macros and functions have been removed.
4589
4590Typecasted NULL definitions such as
4591 #define png_voidp_NULL (png_voidp)NULL
4592were eliminated. If you used these in your application, just use
4593NULL instead.
4594
4595The png_struct and info_struct members "trans" and "trans_values" were
4596changed to "trans_alpha" and "trans_color", respectively.
4597
4598The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4599were removed.
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4600
4601The PNG_1_0_X and PNG_1_2_X macros were eliminated.
4602
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4603The PNG_LEGACY_SUPPORTED macro was eliminated.
4604
4605Many WIN32_WCE #ifdefs were removed.
4606
4607The functions png_read_init(info_ptr), png_write_init(info_ptr),
4608png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
4609have been removed. They have been deprecated since libpng-0.95.
4610
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4611The png_permit_empty_plte() was removed. It has been deprecated
4612since libpng-1.0.9. Use png_permit_mng_features() instead.
4613
4614We removed the obsolete stub functions png_get_mmx_flagmask(),
4615png_set_mmx_thresholds(), png_get_asm_flags(),
4616png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
4617png_set_asm_flags(), and png_mmx_supported()
4618
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4619We removed the obsolete png_check_sig(), png_memcpy_check(), and
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]4620png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
4621and memset(), respectively.
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4622
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4623The function png_set_gray_1_2_4_to_8() was removed. It has been
4624deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
4625png_set_expand_gray_1_2_4_to_8() because the former function also
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4626expanded any tRNS chunk to an alpha channel.
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4627
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4628Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
4629were added and are used by default instead of the corresponding
4630functions. Unfortunately,
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4631from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4632function) incorrectly returned a value of type png_uint_32.
4633
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4634We changed the prototype for png_malloc() from
4635 png_malloc(png_structp png_ptr, png_uint_32 size)
4636to
4637 png_malloc(png_structp png_ptr, png_alloc_size_t size)
4638
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4639This also applies to the prototype for the user replacement malloc_fn().
4640
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4641The png_calloc() function was added and is used in place of
Glenn Randers-Pehrson2be8b642010-07-29 19:09:18 -0500[diff] [blame]4642of "png_malloc(); memset();" except in the case in png_read_png()
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4643where the array consists of pointers; in this case a "for" loop is used
4644after the png_malloc() to set the pointers to NULL, to give robust.
4645behavior in case the application runs out of memory part-way through
4646the process.
4647
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4648We changed the prototypes of png_get_compression_buffer_size() and
4649png_set_compression_buffer_size() to work with png_size_t instead of
4650png_uint_32.
4651
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]4652Support for numbered error messages was removed by default, since we
4653never got around to actually numbering the error messages. The function
4654png_set_strip_error_numbers() was removed from the library by default.
4655
4656The png_zalloc() and png_zfree() functions are no longer exported.
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4657The png_zalloc() function no longer zeroes out the memory that it
4658allocates.
4659
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]4660Support for dithering was disabled by default in libpng-1.4.0, because
4661been well tested and doesn't actually "dither". The code was not
4662removed, however, and could be enabled by building libpng with
4663PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
4664was reenabled, but the function was renamed png_set_quantize() to
4665reflect more accurately what it actually does. At the same time,
4666the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4667PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
4668was renamed to PNG_READ_QUANTIZE_SUPPORTED.
Glenn Randers-Pehrson60988072010-04-13 22:11:06 -0500[diff] [blame]4669
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]4670We removed the trailing '.' from the warning and error messages.
4671
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4672.SH X. Changes to Libpng from version 1.4.x to 1.5.x
4673
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4674From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4675function) incorrectly returned a value of type png_uint_32.
4676
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4677A. Changes that affect users of libpng
4678
4679There are no substantial API changes between the non-deprecated parts of
4680the 1.4.5 API and the 1.5.0 API, however the ability to directly access
4681the main libpng control structures, png_struct and png_info, deprecated
4682in earlier versions of libpng, has been completely removed from
4683libpng 1.5.
4684
Glenn Randers-Pehrson00879b12011-01-15 19:25:34 -0600[diff] [blame]4685We no longer include zlib.h in png.h. Applications that need access
4686to information in zlib.h will need to add the '#include "zlib.h"'
4687directive. It does not matter whether it is placed prior to or after
4688the '"#include png.h"' directive.
4689
4690We moved the png_strcpy(), png_strncpy(), png_strlen(), png_memcpy(),
4691png_memcmp(), png_sprintf, and png_memcpy() macros into a private
4692header file (pngpriv.h) that is not accessible to applications.
4693
Glenn Randers-Pehrson9d23b402011-01-08 10:42:01 -0600[diff] [blame]4694In png_get_iCCP, the type of "profile" was changed from png_charpp
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4695to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
Glenn Randers-Pehrson9d23b402011-01-08 10:42:01 -0600[diff] [blame]4696
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4697There are changes of form in png.h, including new and changed macros to
4698declare
Glenn Randers-Pehrsonf5ea1b72011-01-06 06:42:51 -0600[diff] [blame]4699parts of the API. Some API functions with arguments that are pointers to
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4700data not modified within the function have been corrected to declare
4701these arguments with PNG_CONST.
4702
4703Much of the internal use of C macros to control the library build has also
4704changed and some of this is visible in the exported header files, in
4705particular the use of macros to control data and API elements visible
4706during application compilation may require significant revision to
4707application code. (It is extremely rare for an application to do this.)
4708
4709Any program that compiled against libpng 1.4 and did not use deprecated
4710features or access internal library structures should compile and work
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]4711against libpng 1.5, except for the change in the prototype for
4712png_get_iCCP() and png_set_iCCP() API functions mentioned above.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4713
Glenn Randers-Pehrson6e974102010-12-19 16:44:22 -0600[diff] [blame]4714libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
4715interlaced images. The macros return the number of rows and columns in
4716each pass and information that can be used to de-interlace and (if
4717absolutely necessary) interlace an image.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4718
4719libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
Glenn Randers-Pehrsond08b6bd2011-02-19 15:50:17 -0600[diff] [blame]4720the application-provided png_longjmp_ptr on the internal, but application
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4721initialized, jmpbuf. It is provided as a convenience to avoid the need
4722to use the png_jmpbuf macro, which had the unnecessary side effect of
4723resetting the internal png_longjmp_ptr value.
4724
4725libpng 1.5.0 includes a complete fixed point API. By default this is
4726present along with the corresponding floating point API. In general the
4727fixed point API is faster and smaller than the floating point one because
4728the PNG file format used fixed point, not floating point. This applies
4729even if the library uses floating point in internal calculations. A new
4730macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
4731uses floating point arithmetic (the default) or fixed point arithmetic
4732internally for performance critical calculations such as gamma correction.
Glenn Randers-Pehrson00879b12011-01-15 19:25:34 -0600[diff] [blame]4733In some cases, the gamma calculations may produce slightly different
4734results. This has changed the results in png_rgb_to_gray and in alpha
4735composition (png_set_background for example). This applies even if the
4736original image was already linear (gamma == 1.0) and, therefore, it is
4737not necessary to linearize the image. This is because libpng has *not*
4738been changed to optimize that case correctly, yet.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4739
4740Fixed point support for the sCAL chunk comes with an important caveat;
4741the sCAL specification uses a decimal encoding of floating point values
4742and the accuracy of PNG fixed point values is insufficient for
4743representation of these values. Consequently a "string" API
4744(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
4745arbitrary sCAL chunks in the absence of either the floating point API or
4746internal floating point calculations.
4747
4748Applications no longer need to include the optional distribution header
4749file pngusr.h or define the corresponding macros during application
4750build in order to see the correct variant of the libpng API. From 1.5.0
4751application code can check for the corresponding _SUPPORTED macro:
4752
4753#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
4754 /* code that uses the inch conversion APIs. */
4755#endif
4756
4757This macro will only be defined if the inch conversion functions have been
4758compiled into libpng. The full set of macros, and whether or not support
4759has been compiled in, are available in the header file pnglibconf.h.
4760This header file is specific to the libpng build. Notice that prior to
47611.5.0 the _SUPPORTED macros would always have the default definition unless
4762reset by pngusr.h or by explicit settings on the compiler command line.
4763These settings may produce compiler warnings or errors in 1.5.0 because
4764of macro redefinition.
4765
Glenn Randers-Pehrsonc36bb792011-02-12 09:49:07 -0600[diff] [blame]4766From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4767function) incorrectly returned a value of type png_uint_32. libpng 1.5.0
4768is consistent with the implementation in 1.4.5 and 1.2.x (where the macro
4769did not exist.)
4770
4771Applications can now choose whether to use these macros or to call the
4772corresponding function by defining PNG_USE_READ_MACROS or
4773PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
4774only supported from 1.5.0 -defining PNG_NO_USE_READ_MACROS prior to 1.5.0
4775 will lead to a link failure.
Glenn Randers-Pehrson59fa3e92011-01-06 07:07:06 -0600[diff] [blame]4776
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4777B. Changes to the build and configuration of libpng
4778
4779Details of internal changes to the library code can be found in the CHANGES
4780file. These will be of no concern to the vast majority of library users or
4781builders, however the few who configure libpng to a non-default feature
4782set may need to change how this is done.
4783
4784There should be no need for library builders to alter build scripts if
4785these use the distributed build support - configure or the makefiles -
4786however users of the makefiles may care to update their build scripts
4787to build pnglibconf.h where the corresponding makefile does not do so.
4788
4789Building libpng with a non-default configuration has changed completely.
4790The old method using pngusr.h should still work correctly even though the
4791way pngusr.h is used in the build has been changed, however library
4792builders will probably want to examine the changes to take advantage of
4793new capabilities and to simplify their build system.
4794
4795B.1 Specific changes to library configuration capabilities
4796
4797The library now supports a complete fixed point implementation and can
4798thus be used on systems which have no floating point support or very
4799limited or slow support. Previously gamma correction, an essential part
4800of complete PNG support, required reasonably fast floating point.
4801
4802As part of this the choice of internal implementation has been made
4803independent of the choice of fixed versus floating point APIs and all the
4804missing fixed point APIs have been implemented.
4805
4806The exact mechanism used to control attributes of API functions has
4807changed. A single set of operating system independent macro definitions
4808is used and operating system specific directives are defined in
4809pnglibconf.h
4810
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4811As part of this the mechanism used to choose procedure call standards on
4812those systems that allow a choice has been changed. At present this only
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4813affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
4814running on Intel processors. As before PNGAPI is defined where required
4815to control the exported API functions; however, two new macros, PNGCBAPI
4816and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
4817(PNGCAPI) for functions that must match a C library prototype (currently
4818only png_longjmp_ptr, which must match the C longjmp function.) The new
4819approach is documented in pngconf.h
4820
4821Despite these changes libpng 1.5.0 only supports the native C function
4822calling standard on those platforms tested so far (__cdecl on Microsoft
4823Windows). This is because the support requirements for alternative
4824calling conventions seem to no longer exist. Developers who find it
4825necessary to set PNG_API_RULE to 1 should advise the mailing list
4826(png-mng-implement) of this and library builders who use Openwatcom and
4827therefore set PNG_API_RULE to 2 should also contact the mailing list.
4828
4829A new test program, pngvalid, is provided in addition to pngtest.
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4830pngvalid validates the arithmetic accuracy of the gamma correction
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4831calculations and includes a number of validations of the file format.
4832A subset of the full range of tests is run when "make check" is done
4833(in the 'configure' build.) pngvalid also allows total allocated memory
4834usage to be evaluated and performs additional memory overwrite validation.
4835
4836Many changes to individual feature macros have been made. The following
4837are the changes most likely to be noticed by library builders who
4838configure libpng:
4839
48401) All feature macros now have consistent naming:
4841
4842#define PNG_NO_feature turns the feature off
4843#define PNG_feature_SUPPORTED turns the feature on
4844
4845pnglibconf.h contains one line for each feature macro which is either:
4846
4847#define PNG_feature_SUPPORTED
4848
4849if the feature is supported or:
4850
4851/*#undef PNG_feature_SUPPORTED*/
4852
4853if it is not. Library code consistently checks for the 'SUPPORTED' macro.
4854It does not, and should not, check for the 'NO' macro which will not
4855normally be defined even if the feature is not supported.
4856
4857Compatibility with the old names is provided as follows:
4858
4859PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
4860
4861And the following definitions disable the corresponding feature:
4862
4863PNG_SETJMP_NOT_SUPPORTED disables SETJMP
4864PNG_READ_TRANSFORMS_NOT_SUPPORTED disables READ_TRANSFORMS
4865PNG_NO_READ_COMPOSITED_NODIV disables READ_COMPOSITE_NODIV
4866PNG_WRITE_TRANSFORMS_NOT_SUPPORTED disables WRITE_TRANSFORMS
4867PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED disables READ_ANCILLARY_CHUNKS
4868PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED disables WRITE_ANCILLARY_CHUNKS
4869
4870Library builders should remove use of the above, inconsistent, names.
4871
48722) Warning and error message formatting was previously conditional on
4873the STDIO feature. The library has been changed to use the
4874CONSOLE_IO feature instead. This means that if CONSOLE_IO is disabled
4875the library no longer uses the printf(3) functions, even though the
4876default read/write implementations use (FILE) style stdio.h functions.
4877
48783) Three feature macros now control the fixed/floating point decisions:
4879
4880PNG_FLOATING_POINT_SUPPORTED enables the floating point APIs
4881
4882PNG_FIXED_POINT_SUPPORTED enables the fixed point APIs; however, in
4883practice these are normally required internally anyway (because the PNG
4884file format is fixed point), therefore in most cases PNG_NO_FIXED_POINT
4885merely stops the function from being exported.
4886
4887PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
4888point implementation or the fixed point one. Typically the fixed point
4889implementation is larger and slower than the floating point implementation
4890on a system that supports floating point, however it may be faster on a
4891system which lacks floating point hardware and therefore uses a software
4892emulation.
4893
48944) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
4895functions to read and write ints to be disabled independently of
4896PNG_USE_READ_MACROS, which allows libpng to be built with the functions
4897even though the default is to use the macros - this allows applications
4898to choose at app buildtime whether or not to use macros (previously
4899impossible because the functions weren't in the default build.)
4900
4901B.2 Changes to the configuration mechanism
4902
4903Prior to libpng-1.5.0 library builders who needed to configure libpng
4904had either to modify the exported pngconf.h header file to add system
4905specific configuration or had to write feature selection macros into
4906pngusr.h and cause this to be included into pngconf.h by defining
4907PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
4908application built without PNG_USER_CONFIG defined would see the
4909unmodified, default, libpng API and thus would probably fail to link.
4910
4911These mechanisms still work in the configure build and in any makefile
4912build that builds pnglibconf.h although the feature selection macros
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4913have changed somewhat as described above. In 1.5.0, however, pngusr.h is
4914processed only once, when the exported header file pnglibconf.h is built.
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]4915pngconf.h no longer includes pngusr.h, therefore it is ignored after the
4916build of pnglibconf.h and it is never included in an application build.
4917
4918The rarely used alternative of adding a list of feature macros to the
4919CFLAGS setting in the build also still works, however the macros will be
4920copied to pnglibconf.h and this may produce macro redefinition warnings
4921when the individual C files are compiled.
4922
4923All configuration now only works if pnglibconf.h is built from
4924scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan
4925(the original author of awk) maintains C source code of that awk and this
4926and all known later implementations (often called by subtly different
4927names - nawk and gawk for example) are adequate to build pnglibconf.h.
4928The Sun Microsystems (now Oracle) program 'awk' is an earlier version
4929and does not work, this may also apply to other systems that have a
4930functioning awk called 'nawk'.
4931
4932Configuration options are now documented in scripts/pnglibconf.dfa. This
4933file also includes dependency information that ensures a configuration is
4934consistent; that is, if a feature is switched off dependent features are
4935also removed. As a recommended alternative to using feature macros in
4936pngusr.h a system builder may also define equivalent options in pngusr.dfa
4937(or, indeed, any file) and add that to the configuration by setting
4938DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate
4939how to do this, and a case where pngusr.h is still required.
4940
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4941.SH XI. Detecting libpng
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]4942
4943The png_get_io_ptr() function has been present since libpng-0.88, has never
4944changed, and is unaffected by conditional compilation macros. It is the
4945best choice for use in configure scripts for detecting the presence of any
Glenn Randers-Pehrson99708d52009-06-29 17:30:00 -0500[diff] [blame]4946libpng version since 0.88. In an autoconf "configure.in" you could use
4947
4948 AC_CHECK_LIB(png, png_get_io_ptr, ...
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]4949
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4950.SH XII. Source code repository
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4951
4952Since about February 2009, version 1.2.34, libpng has been under "git" source
4953control. The git repository was built from old libpng-x.y.z.tar.gz files
4954going back to version 0.70. You can access the git repository (read only)
4955at
4956
4957 git://libpng.git.sourceforge.net/gitroot/libpng
4958
4959or you can browse it via "gitweb" at
4960
4961 http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng
4962
4963Patches can be sent to glennrp at users.sourceforge.net or to
4964png-mng-implement at lists.sourceforge.net or you can upload them to
4965the libpng bug tracker at
4966
4967 http://libpng.sourceforge.net
4968
Glenn Randers-Pehrson7bc25012011-01-21 23:29:09 -0600[diff] [blame]4969We also accept patches built from the tar or zip distributions, and
4970simple verbal discriptions of bug fixes, reported either to the
4971SourceForge bug tracker or to the png-mng-implement at lists.sf.net
4972mailing list.
4973
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]4974.SH XIII. Coding style
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4975
4976Our coding style is similar to the "Allman" style, with curly
4977braces on separate lines:
4978
4979 if (condition)
4980 {
4981 action;
4982 }
4983
4984 else if (another condition)
4985 {
4986 another action;
4987 }
4988
4989The braces can be omitted from simple one-line actions:
4990
4991 if (condition)
4992 return (0);
4993
4994We use 3-space indentation, except for continued statements which
4995are usually indented the same as the first line of the statement
4996plus four more spaces.
4997
Glenn Randers-Pehrson5ade7ed2009-09-30 15:11:49 -0500[diff] [blame]4998For macro definitions we use 2-space indentation, always leaving the "#"
4999in the first column.
5000
5001 #ifndef PNG_NO_FEATURE
5002 # ifndef PNG_FEATURE_SUPPORTED
5003 # define PNG_FEATURE_SUPPORTED
5004 # endif
5005 #endif
5006
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5007Comments appear with the leading "/*" at the same indentation as
5008the statement that follows the comment:
5009
5010 /* Single-line comment */
5011 statement;
5012
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]5013 /* This is a multiple-line
5014 * comment.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5015 */
5016 statement;
5017
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]5018Very short comments can be placed after the end of the statement
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5019to which they pertain:
5020
5021 statement; /* comment */
5022
5023We don't use C++ style ("//") comments. We have, however,
5024used them in the past in some now-abandoned MMX assembler
5025code.
5026
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]5027Functions and their curly braces are not indented, and
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5028exported functions are marked with PNGAPI:
5029
5030 /* This is a public function that is visible to
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]5031 * application programmers. It does thus-and-so.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5032 */
5033 void PNGAPI
5034 png_exported_function(png_ptr, png_info, foo)
5035 {
5036 body;
5037 }
5038
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]5039The prototypes for all exported functions appear in png.h,
5040above the comment that says
5041
5042 /* Maintainer: Put new public prototypes here ... */
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5043
5044We mark all non-exported functions with "/* PRIVATE */"":
5045
5046 void /* PRIVATE */
5047 png_non_exported_function(png_ptr, png_info, foo)
5048 {
5049 body;
5050 }
5051
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]5052The prototypes for non-exported functions (except for those in
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]5053pngtest) appear in
5054pngpriv.h
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]5055above the comment that says
5056
5057 /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5058
Glenn Randers-Pehrsoncbbe9a52011-01-29 16:12:11 -0600[diff] [blame]5059To avoid polluting the global namespace, the names of all exported
5060functions and variables begin with "png_", and all publicly visible C
5061preprocessor macros begin with "PNG_". We request that applications that
5062use libpng *not* begin any of their own symbols with either of these strings.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5063
5064We put a space after each comma and after each semicolon
Glenn Randers-Pehrson49a56e72010-12-06 20:06:01 -0600[diff] [blame]5065in "for" statements, and we put spaces before and after each
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]5066C binary operator and after "for" or "while", and before
5067"?". We don't put a space between a typecast and the expression
5068being cast, nor do we put one between a function name and the
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5069left parenthesis that follows it:
5070
5071 for (i = 2; i > 0; --i)
Glenn Randers-Pehrson67f3b482009-09-23 11:36:28 -0500[diff] [blame]5072 y[i] = a(x) + (int)b;
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5073
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]5074We prefer #ifdef and #ifndef to #if defined() and if !defined()
5075when there is only one macro being tested.
5076
Glenn Randers-Pehrson67f3b482009-09-23 11:36:28 -0500[diff] [blame]5077We do not use the TAB character for indentation in the C sources.
5078
Glenn Randers-Pehrson62ca98e2009-12-20 15:14:57 -0600[diff] [blame]5079Lines do not exceed 80 characters.
5080
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]5081Other rules can be inferred by inspecting the libpng source.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5082
Glenn Randers-Pehrson5b40b012010-11-25 07:16:29 -0600[diff] [blame]5083.SH XIV. Y2K Compliance in libpng
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]5084
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]5085March 31, 2011
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5086
5087Since the PNG Development group is an ad-hoc body, we can't make
5088an official declaration.
5089
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5090This is your unofficial assurance that libpng from version 0.71 and
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]5091upward through 1.5.2 are Y2K compliant. It is my belief that earlier
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5092versions were also Y2K compliant.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5093
5094Libpng only has three year fields. One is a 2-byte unsigned integer that
5095will hold years up to 65535. The other two hold the date in text
5096format, and will hold years up to 9999.
5097
5098The integer is
5099 "png_uint_16 year" in png_time_struct.
5100
5101The strings are
5102 "png_charp time_buffer" in png_struct and
5103 "near_time_buffer", which is a local character string in png.c.
5104
5105There are seven time-related functions:
5106
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5107 png_convert_to_rfc_1123() in png.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5108 (formerly png_convert_to_rfc_1152() in error)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5109 png_convert_from_struct_tm() in pngwrite.c, called
5110 in pngwrite.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5111 png_convert_from_time_t() in pngwrite.c
5112 png_get_tIME() in pngget.c
5113 png_handle_tIME() in pngrutil.c, called in pngread.c
5114 png_set_tIME() in pngset.c
5115 png_write_tIME() in pngwutil.c, called in pngwrite.c
5116
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5117All appear to handle dates properly in a Y2K environment. The
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5118png_convert_from_time_t() function calls gmtime() to convert from system
5119clock time, which returns (year - 1900), which we properly convert to
5120the full 4-digit year. There is a possibility that applications using
5121libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5122function, or that they are incorrectly passing only a 2-digit year
5123instead of "year - 1900" into the png_convert_from_struct_tm() function,
5124but this is not under our control. The libpng documentation has always
5125stated that it works with 4-digit years, and the APIs have been
5126documented as such.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5127
5128The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
5129integer to hold the year, and can hold years as large as 65535.
5130
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5131zlib, upon which libpng depends, is also Y2K compliant. It contains
5132no date-related code.
5133
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]5134
5135 Glenn Randers-Pehrson
5136 libpng maintainer
5137 PNG Development Group
5138
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5139.SH NOTE
5140
5141Note about libpng version numbers:
5142
5143Due to various miscommunications, unforeseen code incompatibilities
5144and occasional factors outside the authors' control, version numbering
5145on the library has not always been consistent and straightforward.
5146The following table summarizes matters since version 0.89c, which was
5147the first widely used release:
5148
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5149 source png.h png.h shared-lib
5150 version string int version
5151 ------- ------ ----- ----------
5152 0.89c ("beta 3") 0.89 89 1.0.89
5153 0.90 ("beta 4") 0.90 90 0.90
5154 0.95 ("beta 5") 0.95 95 0.95
5155 0.96 ("beta 6") 0.96 96 0.96
5156 0.97b ("beta 7") 1.00.97 97 1.0.1
5157 0.97c 0.97 97 2.0.97
5158 0.98 0.98 98 2.0.98
5159 0.99 0.99 98 2.0.99
5160 0.99a-m 0.99 99 2.0.99
5161 1.00 1.00 100 2.1.0
5162 1.0.0 1.0.0 100 2.1.0
5163 1.0.0 (from here on, the 100 2.1.0
5164 1.0.1 png.h string is 10001 2.1.0
5165 1.0.1a-e identical to the 10002 from here on, the
5166 1.0.2 source version) 10002 shared library is 2.V
5167 1.0.2a-b 10003 where V is the source
5168 1.0.1 10001 code version except as
5169 1.0.1a-e 10002 2.1.0.1a-e noted.
5170 1.0.2 10002 2.1.0.2
5171 1.0.2a-b 10003 2.1.0.2a-b
5172 1.0.3 10003 2.1.0.3
5173 1.0.3a-d 10004 2.1.0.3a-d
5174 1.0.4 10004 2.1.0.4
5175 1.0.4a-f 10005 2.1.0.4a-f
5176 1.0.5 (+ 2 patches) 10005 2.1.0.5
5177 1.0.5a-d 10006 2.1.0.5a-d
5178 1.0.5e-r 10100 2.1.0.5e-r
5179 1.0.5s-v 10006 2.1.0.5s-v
5180 1.0.6 (+ 3 patches) 10006 2.1.0.6
5181 1.0.6d-g 10007 2.1.0.6d-g
5182 1.0.6h 10007 10.6h
5183 1.0.6i 10007 10.6i
5184 1.0.6j 10007 2.1.0.6j
Glenn Randers-Pehrson25467032011-01-28 11:58:40 -0600[diff] [blame]5185 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5186 1.0.7beta15-18 1 10007 2.1.0.7beta15-18
5187 1.0.7rc1-2 1 10007 2.1.0.7rc1-2
5188 1.0.7 1 10007 2.1.0.7
5189 1.0.8beta1-4 1 10008 2.1.0.8beta1-4
5190 1.0.8rc1 1 10008 2.1.0.8rc1
5191 1.0.8 1 10008 2.1.0.8
5192 1.0.9beta1-6 1 10009 2.1.0.9beta1-6
5193 1.0.9rc1 1 10009 2.1.0.9rc1
5194 1.0.9beta7-10 1 10009 2.1.0.9beta7-10
5195 1.0.9rc2 1 10009 2.1.0.9rc2
5196 1.0.9 1 10009 2.1.0.9
Glenn Randers-Pehrsone1644472001-03-23 05:06:56 -0600[diff] [blame]5197 1.0.10beta1 1 10010 2.1.0.10beta1
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5198 1.0.10rc1 1 10010 2.1.0.10rc1
Glenn Randers-Pehrson13cfbac2001-03-30 06:42:28 -0600[diff] [blame]5199 1.0.10 1 10010 2.1.0.10
Glenn Randers-Pehrsone1eff582001-04-14 20:15:41 -0500[diff] [blame]5200 1.0.11beta1-3 1 10011 2.1.0.11beta1-3
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]5201 1.0.11rc1 1 10011 2.1.0.11rc1
Glenn Randers-Pehrson32835392001-04-27 08:29:32 -0500[diff] [blame]5202 1.0.11 1 10011 2.1.0.11
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]5203 1.0.12beta1-2 2 10012 2.1.0.12beta1-2
5204 1.0.12rc1 2 10012 2.1.0.12rc1
5205 1.0.12 2 10012 2.1.0.12
5206 1.1.0a-f - 10100 2.1.1.0a-f abandoned
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]5207 1.2.0beta1-2 2 10200 2.1.2.0beta1-2
Glenn Randers-Pehrson5a0be342001-10-18 20:55:13 -0500[diff] [blame]5208 1.2.0beta3-5 3 10200 3.1.2.0beta3-5
5209 1.2.0rc1 3 10200 3.1.2.0rc1
5210 1.2.0 3 10200 3.1.2.0
Glenn Randers-Pehrson5cded0b2001-11-07 07:10:08 -0600[diff] [blame]5211 1.2.1beta-4 3 10201 3.1.2.1beta1-4
Glenn Randers-Pehrsondb3b88d2001-12-04 06:30:43 -0600[diff] [blame]5212 1.2.1rc1-2 3 10201 3.1.2.1rc1-2
5213 1.2.1 3 10201 3.1.2.1
Glenn Randers-Pehrson25228ab2002-03-31 07:33:55 -0600[diff] [blame]5214 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6
Glenn Randers-Pehrsonfcbd7872002-04-07 16:35:38 -0500[diff] [blame]5215 1.0.13beta1 10 10013 10.so.0.1.0.13beta1
5216 1.0.13rc1 10 10013 10.so.0.1.0.13rc1
5217 1.2.2rc1 12 10202 12.so.0.1.2.2rc1
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]5218 1.0.13 10 10013 10.so.0.1.0.13
5219 1.2.2 12 10202 12.so.0.1.2.2
Glenn Randers-Pehrson22f28962002-05-13 18:17:09 -0500[diff] [blame]5220 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6
5221 1.2.3 12 10203 12.so.0.1.2.3
Glenn Randers-Pehrsond020e9d2002-06-28 09:34:00 -0500[diff] [blame]5222 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3
Glenn Randers-Pehrson2ae022d2002-07-01 22:23:46 -0500[diff] [blame]5223 1.2.4rc1 13 10204 12.so.0.1.2.4rc1
Glenn Randers-Pehrson484a8a12002-07-07 19:15:20 -0500[diff] [blame]5224 1.0.14 10 10014 10.so.0.1.0.14
5225 1.2.4 13 10204 12.so.0.1.2.4
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]5226 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2
5227 1.0.15rc1 10 10015 10.so.0.1.0.15rc1
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5228 1.0.15 10 10015 10.so.0.1.0.15
5229 1.2.5 13 10205 12.so.0.1.2.5
5230 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4
Glenn Randers-Pehrson37f116a2004-08-15 07:15:39 -0500[diff] [blame]5231 1.2.6rc1-5 13 10206 12.so.0.1.2.6rc1-5
5232 1.0.16 10 10016 10.so.0.1.0.16
5233 1.2.6 13 10206 12.so.0.1.2.6
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]5234 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]5235 1.0.17rc1 10 10017 12.so.0.1.0.17rc1
5236 1.2.7rc1 13 10207 12.so.0.1.2.7rc1
Glenn Randers-Pehrson250dfe12004-09-11 21:19:54 -0500[diff] [blame]5237 1.0.17 10 10017 12.so.0.1.0.17
5238 1.2.7 13 10207 12.so.0.1.2.7
Glenn Randers-Pehrson40936072004-11-20 11:18:40 -0600[diff] [blame]5239 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5
Glenn Randers-Pehrson584b96e2004-11-29 15:08:00 -0600[diff] [blame]5240 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5
5241 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5
Glenn Randers-Pehrson917648e2004-12-02 18:14:51 -0600[diff] [blame]5242 1.0.18 10 10018 12.so.0.1.0.18
5243 1.2.8 13 10208 12.so.0.1.2.8
Glenn Randers-Pehrsone6474622006-03-04 16:50:47 -0600[diff] [blame]5244 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3
Glenn Randers-Pehrson4deeb792006-03-22 16:21:59 -0600[diff] [blame]5245 1.2.9beta4-11 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrson3a512032006-03-31 05:29:33 -0600[diff] [blame]5246 1.2.9rc1 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsona7d0c942006-04-14 06:22:52 -0500[diff] [blame]5247 1.2.9 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]5248 1.2.10beta1-7 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson17218292006-04-20 07:20:46 -0500[diff] [blame]5249 1.2.10rc1-2 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson86dc9812006-05-10 07:27:44 -0500[diff] [blame]5250 1.2.10 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]5251 1.4.0beta1-6 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]5252 1.2.11beta1-4 13 10210 12.so.0.11[.0]
Glenn Randers-Pehrson3424ee72006-07-12 13:33:47 -0500[diff] [blame]5253 1.4.0beta7-8 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrson701dbaa2006-11-17 09:36:54 -0600[diff] [blame]5254 1.2.11 13 10211 12.so.0.11[.0]
5255 1.2.12 13 10212 12.so.0.12[.0]
5256 1.4.0beta9-14 14 10400 14.so.0.0[.0]
5257 1.2.13 13 10213 12.so.0.13[.0]
Glenn Randers-Pehrson97a9b482008-10-25 20:03:28 -0500[diff] [blame]5258 1.4.0beta15-36 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrsonfa028102009-10-10 06:15:21 -0500[diff] [blame]5259 1.4.0beta37-87 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson733da8c2009-10-30 00:00:15 -0500[diff] [blame]5260 1.4.0rc01 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson62ca98e2009-12-20 15:14:57 -0600[diff] [blame]5261 1.4.0beta88-109 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson67a83db2010-01-01 18:26:18 -0600[diff] [blame]5262 1.4.0rc02-08 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsondbcfb712009-12-25 14:24:18 -0600[diff] [blame]5263 1.4.0 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]5264 1.4.1beta01-03 14 10401 14.so.14.1[.0]
5265 1.4.1rc01 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrson7a5be532010-02-14 07:16:19 -0600[diff] [blame]5266 1.4.1beta04-12 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrsonaaf377c2010-03-08 11:20:30 -0600[diff] [blame]5267 1.4.1 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame]5268 1.4.2 14 10402 14.so.14.2[.0]
5269 1.4.3 14 10403 14.so.14.3[.0]
Glenn Randers-Pehrson2776d5e2010-11-21 15:18:02 -0600[diff] [blame]5270 1.4.4 14 10404 14.so.14.4[.0]
Glenn Randers-Pehrsonfd20a5a2010-12-27 08:53:08 -0600[diff] [blame]5271 1.5.0beta01-58 15 10500 15.so.15.0[.0]
Glenn Randers-Pehrson64b863c2011-01-04 09:57:06 -0600[diff] [blame]5272 1.5.0rc01-07 15 10500 15.so.15.0[.0]
Glenn Randers-Pehrsonf5ea1b72011-01-06 06:42:51 -0600[diff] [blame]5273 1.5.0 15 10500 15.so.15.0[.0]
Glenn Randers-Pehrsonef123cc2011-01-28 15:20:34 -0600[diff] [blame]5274 1.5.1beta01-11 15 10501 15.so.15.1[.0]
Glenn Randers-Pehrson3d3aae12011-02-02 22:58:27 -0600[diff] [blame]5275 1.5.1rc01-02 15 10501 15.so.15.1[.0]
5276 1.5.1 15 10501 15.so.15.1[.0]
Glenn Randers-Pehrsonf3dd1cc2011-03-18 22:02:20 -0500[diff] [blame]5277 1.5.2beta01-03 15 10502 15.so.15.2[.0]
Glenn Randers-Pehrson77fd0832011-03-24 08:59:48 -0500[diff] [blame]5278 1.5.2rc01-03 15 10502 15.so.15.2[.0]
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]5279 1.5.2 15 10502 15.so.15.2[.0]
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5280
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5281Henceforth the source version will match the shared-library minor
5282and patch numbers; the shared-library major version number will be
5283used for changes in backward compatibility, as it is intended. The
5284PNG_PNGLIB_VER macro, which is not used within libpng but is available
5285for applications, is an unsigned integer of the form xyyzz corresponding
5286to the source version x.y.z (leading zeros in y and z). Beta versions
Glenn Randers-Pehrsone1644472001-03-23 05:06:56 -0600[diff] [blame]5287were given the previous public release number plus a letter, until
5288version 1.0.6j; from then on they were given the upcoming public
5289release number plus "betaNN" or "rcN".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5290
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5291.SH "SEE ALSO"
Glenn Randers-Pehrson4e763f12010-03-03 10:45:50 -0600[diff] [blame]5292.BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
Glenn Randers-Pehrson7fb32a82010-03-03 09:47:49 -0600[diff] [blame]5293
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5294.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5295.IR libpng :
5296.IP
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]5297http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]5298http://www.libpng.org/pub/png
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5299
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5300.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5301.IR zlib :
5302.IP
5303(generally) at the same location as
5304.I libpng
5305or at
5306.br
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]5307ftp://ftp.info-zip.org/pub/infozip/zlib
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5308
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5309.LP
5310.IR PNG specification: RFC 2083
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5311.IP
5312(generally) at the same location as
5313.I libpng
5314or at
5315.br
5316ftp://ds.internic.net/rfc/rfc2083.txt
5317.br
5318or (as a W3C Recommendation) at
5319.br
5320http://www.w3.org/TR/REC-png.html
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5321
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]5322.LP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5323In the case of any inconsistency between the PNG specification
5324and this library, the specification takes precedence.
5325
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5326.SH AUTHORS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5327This man page: Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]5328<glennrp at users.sourceforge.net>
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5329
5330The contributing authors would like to thank all those who helped
5331with testing, bug fixes, and patience. This wouldn't have been
5332possible without all of you.
5333
5334Thanks to Frank J. T. Wojcik for helping with the documentation.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]5335
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]5336Libpng version 1.5.2 - March 31, 2011:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5337Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]5338Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5339
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5340Supported by the PNG development group
5341.br
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]5342png-mng-implement at lists.sf.net
5343(subscription required; visit
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]5344png-mng-implement at lists.sourceforge.net (subscription required; visit
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]5345https://lists.sourceforge.net/lists/listinfo/png-mng-implement
5346to subscribe).
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5347
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5348.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5349
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]5350(This copy of the libpng notices is provided for your convenience. In case of
5351any discrepancy between this copy and the notices in the file png.h that is
5352included in the libpng distribution, the latter shall prevail.)
5353
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5354If you modify libpng you may insert additional notices immediately following
5355this sentence.
5356
Glenn Randers-Pehrsonbfbf8652009-06-26 21:46:52 -0500[diff] [blame]5357This code is released under the libpng license.
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]5358
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]5359libpng versions 1.2.6, August 15, 2004, through 1.5.2, March 31, 2011, are
Glenn Randers-Pehrsona7dbcba2007-05-15 16:16:34 -0500[diff] [blame]5360Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5361distributed according to the same disclaimer and license as libpng-1.2.5
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]5362with the following individual added to the list of Contributing Authors
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5363
5364 Cosmin Truta
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]5365
5366libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are
Glenn Randers-Pehrsonc6de22d2002-02-23 18:55:25 -0600[diff] [blame]5367Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson32fc5ce2000-07-24 06:34:14 -0500[diff] [blame]5368distributed according to the same disclaimer and license as libpng-1.0.6
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5369with the following individuals added to the list of Contributing Authors
5370
5371 Simon-Pierre Cadieux
5372 Eric S. Raymond
5373 Gilles Vollant
5374
5375and with the following additions to the disclaimer:
5376
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]5377 There is no warranty against interference with your
5378 enjoyment of the library or against infringement.
5379 There is no warranty that our efforts or the library
5380 will fulfill any of your particular purposes or needs.
5381 This library is provided with all faults, and the entire
5382 risk of satisfactory quality, performance, accuracy, and
5383 effort is with the user.
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5384
5385libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
5386Copyright (c) 1998, 1999 Glenn Randers-Pehrson
5387Distributed according to the same disclaimer and license as libpng-0.96,
5388with the following individuals added to the list of Contributing Authors:
5389
5390 Tom Lane
5391 Glenn Randers-Pehrson
5392 Willem van Schaik
5393
5394libpng versions 0.89, June 1996, through 0.96, May 1997, are
Glenn Randers-Pehrson54a066a1999-09-19 06:04:18 -0500[diff] [blame]5395Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5396Distributed according to the same disclaimer and license as libpng-0.88,
5397with the following individuals added to the list of Contributing Authors:
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5398
5399 John Bowler
5400 Kevin Bracey
5401 Sam Bushell
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5402 Magnus Holmgren
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5403 Greg Roelofs
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5404 Tom Tanner
5405
5406libpng versions 0.5, May 1995, through 0.88, January 1996, are
5407Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
5408
5409For the purposes of this copyright and license, "Contributing Authors"
5410is defined as the following set of individuals:
5411
5412 Andreas Dilger
5413 Dave Martindale
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5414 Guy Eric Schalnat
5415 Paul Schmidt
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5416 Tim Wegner
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]5417
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5418The PNG Reference Library is supplied "AS IS". The Contributing Authors
5419and Group 42, Inc. disclaim all warranties, expressed or implied,
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5420including, without limitation, the warranties of merchantability and of
5421fitness for any purpose. The Contributing Authors and Group 42, Inc.
5422assume no liability for direct, indirect, incidental, special, exemplary,
5423or consequential damages, which may result from the use of the PNG
5424Reference Library, even if advised of the possibility of such damage.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]5425
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5426Permission is hereby granted to use, copy, modify, and distribute this
5427source code, or portions hereof, for any purpose, without fee, subject
5428to the following restrictions:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5429
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]54301. The origin of this source code must not be misrepresented.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5431
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]54322. Altered versions must be plainly marked as such and
5433 must not be misrepresented as being the original source.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5434
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]54353. This Copyright notice may not be removed or altered from
5436 any source or altered source distribution.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5437
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5438The Contributing Authors and Group 42, Inc. specifically permit, without
5439fee, and encourage the use of this source code as a component to
5440supporting the PNG file format in commercial products. If you use this
5441source code in a product, acknowledgment is not required but would be
5442appreciated.
5443
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5444
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5445A "png_get_copyright" function is available, for convenient use in "about"
5446boxes and the like:
5447
5448 printf("%s",png_get_copyright(NULL));
5449
5450Also, the PNG logo (in PNG format, of course) is supplied in the
Glenn Randers-Pehrsona4d54bd2000-07-14 08:15:12 -0500[diff] [blame]5451files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]5452
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5453Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]5454certification mark of the Open Source Initiative.
5455
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5456Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]5457glennrp at users.sourceforge.net
Glenn Randers-Pehrsondcc35052011-03-31 11:23:49 -0500[diff] [blame^]5458March 31, 2011
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]5459
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]5460.\" end of man page
5461