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gerrit-public.fairphone.software / platform / external / libpng / 5b3d554e1e8eb905bed7a97600d816c26f28867a / . / libpng.3
blob: 282409a575837070c56fc6f37197535d07beb04c [file] [log] [blame]
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]1.TH LIBPNG 3 "June 19, 2010"
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]2.SH NAME
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]3libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta26
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
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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-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]19\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]21\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]23\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]24
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]25\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]27\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]28
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_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]32
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]33\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]35\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]36
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]37\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]39\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]40
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]41\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]43\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\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
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Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]47\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]48
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]49\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]51\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
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]53\fI\fB
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Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]55\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]56
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]57\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]59\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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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]61\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]63\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]65\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]67\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]69\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]71\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]73\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]75\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]77\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]79\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]81\fI\fB
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Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]83\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]85\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]87\fBvoid png_free_default(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]89\fI\fB
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Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]91\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]92
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\fBpng_byte png_get_bit_depth (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]97\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]99\fBpng_uint_32 png_get_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\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-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]103\fBpng_byte png_get_channels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]105\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]107\fBpng_uint_32 png_get_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_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
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]109\fI\fB
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Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]111\fBpng_uint_32 png_get_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_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
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]113\fI\fB
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Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]115\fBpng_uint_32 png_get_chunk_cache_max (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]117\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]119\fBpng_byte png_get_color_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]121\fI\fB
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Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]123\fBpng_uint_32 png_get_compression_buffer_size (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]125\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]127\fBpng_byte png_get_compression_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]129\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]131\fBpng_byte png_get_copyright (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]133\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]135\fBpng_voidp png_get_error_ptr (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]137\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]139\fBpng_byte png_get_filter_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]141\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]143\fBpng_uint_32 png_get_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]145\fI\fB
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Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]147\fBpng_uint_32 png_get_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]149\fI\fB
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Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]151\fBpng_byte png_get_header_ver (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]153\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]155\fBpng_byte png_get_header_version (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]157\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]159\fBpng_uint_32 png_get_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]161\fI\fB
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Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]163\fBpng_uint_32 png_get_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_charpp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]164
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]165\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]167\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
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]169\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]171\fBpng_uint_32 png_get_image_height (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]173\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]175\fBpng_uint_32 png_get_image_width (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]177\fI\fB
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]179\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]181\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]182
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]183\fBpng_byte png_get_interlace_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]185\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]187\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]189\fI\fB
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Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]191\fBpng_byte png_get_libpng_ver (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]193\fI\fB
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Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]195\fBpng_alloc_size_t png_get_chunk_malloc_max (png_structp \fIpng_ptr\fP\fB);\fP
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197\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]199\fBpng_voidp png_get_mem_ptr(png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]201\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]203\fBpng_uint_32 png_get_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_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
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]205\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]207\fBpng_uint_32 png_get_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_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
208
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]209\fI\fB
210
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]211\fBpng_uint_32 png_get_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_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
212
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]213\fI\fB
214
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]215\fBfloat png_get_pixel_aspect_ratio (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
216
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]217\fI\fB
218
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]219\fBpng_uint_32 png_get_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
220
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]221\fI\fB
222
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]223\fBpng_voidp png_get_progressive_ptr (png_structp \fIpng_ptr\fP\fB);\fP
224
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]225\fI\fB
226
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]227\fBpng_uint_32 png_get_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
228
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]229\fI\fB
230
231\fBpng_byte png_get_rgb_to_gray_status (png_structp \fIpng_ptr)
232
233\fBpng_uint_32 png_get_rowbytes (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
234
235\fI\fB
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]236
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]237\fBpng_bytepp png_get_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
238
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]239\fI\fB
240
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]241\fBpng_uint_32 png_get_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
242
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]243\fI\fB
244
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]245\fBpng_bytep png_get_signature (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
246
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]247\fI\fB
248
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]249\fBpng_uint_32 png_get_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_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]250
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]251\fI\fB
252
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]253\fBpng_uint_32 png_get_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fI*intent\fP\fB);\fP
254
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]255\fI\fB
256
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]257\fBpng_uint_32 png_get_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
258
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]259\fI\fB
260
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]261\fBpng_uint_32 png_get_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
262
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]263\fI\fB
264
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]265\fBpng_uint_32 png_get_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans\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]266
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]267\fI\fB
268
269\fB/* This function is really an inline macro. \fI*/
270
271\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
272
273\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]274
275\fBpng_uint_32 png_get_uint_31 (png_bytep \fIbuf\fP\fB);\fP
276
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]277\fI\fB
278
279\fB/* This function is really an inline macro. \fI*/
280
281\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
282
283\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]284
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]285\fBpng_uint_32 png_get_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]287\fI\fB
288
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]289\fBpng_voidp png_get_user_chunk_ptr (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]291\fI\fB
292
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]293\fBpng_uint_32 png_get_user_height_max( png_structp \fIpng_ptr\fP\fB);\fP
294
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]295\fI\fB
296
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]297\fBpng_voidp png_get_user_transform_ptr (png_structp \fIpng_ptr\fP\fB);\fP
298
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]299\fI\fB
300
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]301\fBpng_uint_32 png_get_user_width_max (png_structp \fIpng_ptr\fP\fB);\fP
302
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]303\fI\fB
304
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]305\fBpng_uint_32 png_get_valid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
306
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]307\fI\fB
308
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]309\fBpng_int_32 png_get_x_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]310
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]311\fI\fB
312
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]313\fBpng_int_32 png_get_x_offset_pixels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]314
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]315\fI\fB
316
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]317\fBpng_uint_32 png_get_x_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
318
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]319\fI\fB
320
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]321\fBpng_int_32 png_get_y_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]322
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]323\fI\fB
324
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]325\fBpng_int_32 png_get_y_offset_pixels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]326
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]327\fI\fB
328
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]329\fBpng_uint_32 png_get_y_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]331\fI\fB
332
Glenn Randers-Pehrsonc1bfe682002-03-06 22:08:00 -0600[diff] [blame]333\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]335\fI\fB
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Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]337\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]338
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]339\fI\fB
340
Glenn Randers-Pehrsonf98726a2010-02-19 09:54:53 -0600[diff] [blame]341\fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP
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343\fI\fB
344
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]345\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]346
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]347\fI\fB
348
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]349\fBpng_voidp png_malloc_default(png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]350
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]351\fI\fB
352
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]353\fBvoidp png_memcpy (png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_size_t \fIsize\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]355\fI\fB
356
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]357\fBvoidp png_memset (png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_size_t \fIsize\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]359\fI\fB
360
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]361\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
362
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]363\fI\fB
364
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]365\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
366
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]367\fI\fB
368
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]369\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]371\fI\fB
372
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]373\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]375\fI\fB
376
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]377\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]379\fI\fB
380
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]381\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]382
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]383\fI\fB
384
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]385\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
386
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]387\fI\fB
388
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]389\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
390
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]391\fI\fB
392
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]393\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
394
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]395\fI\fB
396
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]397\fBpng_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
398
399\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]400
401\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
402
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]403\fI\fB
404
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]405\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
406
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]407\fI\fB
408
409\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
410
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]411\fI\fB
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]412
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]413\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
414
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]415\fI\fB
416
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]417\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
418
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]419\fI\fB
420
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]421\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
422
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]423\fI\fB
424
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]425\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
426
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]427\fI\fB
428
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]429\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
430
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]431\fI\fB
432
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]433\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
434
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]435\fI\fB
436
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]437\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
438
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]439\fI\fB
440
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]441\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
442
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]443\fI\fB
444
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]445\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
446
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]447\fI\fB
448
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]449\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]450
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]451\fI\fB
452
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]453\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]454
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]455\fI\fB
456
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]457\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]458
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]459\fI\fB
460
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]461\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]462
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]463\fI\fB
464
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]465\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]466
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]467\fI\fB
468
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]469\fBvoid png_set_expand_gray_1_2_4_to_8(png_structp \fIpng_ptr\fP\fB);\fP
470
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]471\fI\fB
472
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]473\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]474
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]475\fI\fB
476
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]477\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]478
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]479\fI\fB
480
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]481\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]482
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]483\fI\fB
484
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]485\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]486
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]487\fI\fB
488
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]489\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]490
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]491\fI\fB
492
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]493\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]494
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]495\fI\fB
496
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]497\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
498
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]499\fI\fB
500
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]501\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]502
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]503\fI\fB
504
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]505\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]506
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]507\fI\fB
508
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]509\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]510
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]511\fI\fB
512
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]513\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_charp \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]514
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]515\fI\fB
516
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]517\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]518
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]519\fI\fB
520
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]521\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
522
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]523\fI\fB
524
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]525\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]526
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]527\fI\fB
528
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]529\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]530
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]531\fI\fB
532
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]533\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]534
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]535\fI\fB
536
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]537\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]538
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]539\fI\fB
540
Glenn Randers-Pehrson1e6ed732009-11-20 22:06:56 -0600[diff] [blame]541\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
542
543\fI\fB
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Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]545\fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP
546
547\fI\fB
548
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]549\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]550
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]551\fI\fB
552
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]553\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]554
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]555\fI\fB
556
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]557\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]558
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]559\fI\fB
560
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]561\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]562
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]563\fI\fB
564
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]565\fBvoid png_set_palette_to_rgb(png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]566
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]567\fI\fB
568
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]569\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]570
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]571\fI\fB
572
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]573\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]574
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]575\fI\fB
576
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]577\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]578
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]579\fI\fB
580
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]581\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]582
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]583\fI\fB
584
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]585\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
586
587\fI\fB
588
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]589\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]590
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]591\fI\fB
592
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]593\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]594
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]595\fI\fB
596
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]597\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]598
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]599\fI\fB
600
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]601\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
602
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]603\fI\fB
604
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]605\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_fixed_point \fP\fIred\fP\fB, png_fixed_point \fIgreen\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]606
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]607\fI\fB
608
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]609\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
610
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]611\fI\fB
612
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]613\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]614
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]615\fI\fB
616
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]617\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
618
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]619\fI\fB
620
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]621\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]622
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]623\fI\fB
624
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]625\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]626
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]627\fI\fB
628
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]629\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]630
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]631\fI\fB
632
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]633\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIintent\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]634
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]635\fI\fB
636
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]637\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIintent\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]638
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]639\fI\fB
640
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]641\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]642
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]643\fI\fB
644
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]645\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]646
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]647\fI\fB
648
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]649\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]650
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]651\fI\fB
652
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]653\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]654
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]655\fI\fB
656
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]657\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]658
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]659\fI\fB
660
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]661\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]662
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]663\fI\fB
664
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]665\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans\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]666
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]667\fI\fB
668
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]669\fBvoid png_set_tRNS_to_alpha(png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]670
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]671\fI\fB
672
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]673\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
674
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]675\fI\fB
676
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]677\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
678
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]679\fI\fB
680
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]681\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
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]682
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]683\fI\fB
684
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]685\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
686
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]687\fI\fB
688
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]689\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]690
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]691\fI\fB
692
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]693\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]694
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]695\fI\fB
696
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]697\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]698
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]699\fI\fB
700
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]701\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]702
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]703\fI\fB
704
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]705\fBvoid png_set_compression_buffer_size(png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
706
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]707\fI\fB
708
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]709\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]710
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]711\fI\fB
712
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]713\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]714
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]715\fI\fB
716
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]717\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]718
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]719\fI\fB
720
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]721\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]722
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]723\fI\fB
724
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]725\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]726
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]727\fI\fB
728
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]729\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]730
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]731\fI\fB
732
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]733\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]734
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]735\fI\fB
736
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]737\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]738
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]739\fI\fB
740
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]741\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]742
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]743\fI\fB
744
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]745\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]746
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]747\fI\fB
748
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]749\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]750
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]751\fI\fB
752
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]753\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
754
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]755\fI\fB
756
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]757\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]758
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]759\fI\fB
760
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]761\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]762
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]763\fI\fB
764
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]765\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]766
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]767\fI\fB
768
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]769\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
770
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]771\fI\fB
772
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]773\fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP
774
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]775\fI\fB
776
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]777\fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP
778
Glenn Randers-Pehrsonad81d712009-07-30 15:39:00 -0500[diff] [blame]779\fI\fB
780
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]781.SH DESCRIPTION
782The
783.I libpng
784library supports encoding, decoding, and various manipulations of
785the Portable Network Graphics (PNG) format image files. It uses the
786.IR zlib(3)
787compression library.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]788Following is a copy of the libpng.txt file that accompanies libpng.
789.SH LIBPNG.TXT
790libpng.txt - A description on how to use and modify libpng
791
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]792 libpng version 1.5.0beta26 - June 19, 2010
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]793 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]794 <glennrp at users.sourceforge.net>
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]795 Copyright (c) 1998-2009 Glenn Randers-Pehrson
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]796
Glenn Randers-Pehrsonbfbf8652009-06-26 21:46:52 -0500[diff] [blame]797 This document is released under the libpng license.
Glenn Randers-Pehrsonc332bbc2009-06-25 13:43:50 -0500[diff] [blame]798 For conditions of distribution and use, see the disclaimer
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]799 and license in png.h
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]800
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]801 Based on:
802
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]803 libpng versions 0.97, January 1998, through 1.5.0beta26 - June 19, 2010
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]804 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrsona93c9422009-04-13 11:41:33 -0500[diff] [blame]805 Copyright (c) 1998-2009 Glenn Randers-Pehrson
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]806
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]807 libpng 1.0 beta 6 version 0.96 May 28, 1997
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]808 Updated and distributed by Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]809 Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]810
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]811 libpng 1.0 beta 2 - version 0.88 January 26, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]812 For conditions of distribution and use, see copyright
813 notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]814 Schalnat, Group 42, Inc.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]815
816 Updated/rewritten per request in the libpng FAQ
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]817 Copyright (c) 1995, 1996 Frank J. T. Wojcik
818 December 18, 1995 & January 20, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]819
820.SH I. Introduction
821
822This file describes how to use and modify the PNG reference library
823(known as libpng) for your own use. There are five sections to this
824file: introduction, structures, reading, writing, and modification and
825configuration notes for various special platforms. In addition to this
826file, example.c is a good starting point for using the library, as
827it is heavily commented and should include everything most people
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]828will need. We assume that libpng is already installed; see the
829INSTALL file for instructions on how to install libpng.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]830
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]831For examples of libpng usage, see the files "example.c", "pngtest.c",
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]832and the files in the "contrib" directory, all of which are included in
833the libpng distribution.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]834
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]835Libpng was written as a companion to the PNG specification, as a way
836of reducing the amount of time and effort it takes to support the PNG
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]837file format in application programs.
838
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]839The PNG specification (second edition), November 2003, is available as
840a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
841<http://www.w3.org/TR/2003/REC-PNG-20031110/
842The W3C and ISO documents have identical technical content.
843
844The PNG-1.2 specification is available at
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]845<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
846to the PNG specification (second edition) but has some additional material.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]847
848The PNG-1.0 specification is available
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]849as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]850W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
851
852Some additional chunks are described in the special-purpose public chunks
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]853documents at <http://www.libpng.org/pub/png/documents/>.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]854
855Other information
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]856about 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]857page, <http://www.libpng.org/pub/png/>.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]858
859Most users will not have to modify the library significantly; advanced
860users may want to modify it more. All attempts were made to make it as
861complete as possible, while keeping the code easy to understand.
862Currently, this library only supports C. Support for other languages
863is being considered.
864
865Libpng has been designed to handle multiple sessions at one time,
866to be easily modifiable, to be portable to the vast majority of
867machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
868to use. The ultimate goal of libpng is to promote the acceptance of
869the PNG file format in whatever way possible. While there is still
870work to be done (see the TODO file), libpng should cover the
871majority of the needs of its users.
872
873Libpng uses zlib for its compression and decompression of PNG files.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]874Further information about zlib, and the latest version of zlib, can
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]875be 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]876The zlib compression utility is a general purpose utility that is
877useful for more than PNG files, and can be used without libpng.
878See the documentation delivered with zlib for more details.
879You can usually find the source files for the zlib utility wherever you
880find the libpng source files.
881
882Libpng is thread safe, provided the threads are using different
883instances of the structures. Each thread should have its own
884png_struct and png_info instances, and thus its own image.
885Libpng does not protect itself against two threads using the
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]886same instance of a structure.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]887
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]888.SH II. Structures
889
890There are two main structures that are important to libpng, png_struct
891and png_info. The first, png_struct, is an internal structure that
892will not, for the most part, be used by a user except as the first
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]893variable passed to every libpng function call.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]894
895The png_info structure is designed to provide information about the
896PNG file. At one time, the fields of png_info were intended to be
897directly accessible to the user. However, this tended to cause problems
898with applications using dynamically loaded libraries, and as a result
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]899a set of interface functions for png_info (the png_get_*() and png_set_*()
900functions) was developed. The fields of png_info are still available for
901older applications, but it is suggested that applications use the new
902interfaces if at all possible.
903
904Applications that do make direct access to the members of png_struct (except
905for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
906and applications that make direct access to the members of png_info must
907be recompiled if they were compiled or loaded with libpng version 1.0.6,
908in which the members were in a different order. In version 1.0.7, the
909members of the png_info structure reverted to the old order, as they were
910in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
911structures are going to be hidden, and the contents of the structures will
912only be accessible through the png_get/png_set functions.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]913
914The png.h header file is an invaluable reference for programming with libpng.
915And while I'm on the topic, make sure you include the libpng header file:
916
917#include <png.h>
918
919.SH III. Reading
920
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]921We'll now walk you through the possible functions to call when reading
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]922in a PNG file sequentially, briefly explaining the syntax and purpose
923of each one. See example.c and png.h for more detail. While
924progressive reading is covered in the next section, you will still
925need some of the functions discussed in this section to read a PNG
926file.
927
928.SS Setup
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]929
930You will want to do the I/O initialization(*) before you get into libpng,
931so if it doesn't work, you don't have much to undo. Of course, you
932will also want to insure that you are, in fact, dealing with a PNG
933file. 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]934To 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]935png_sig_cmp(), and it will return 0 (false) if the bytes match the
936corresponding bytes of the PNG signature, or nonzero (true) otherwise.
937Of course, the more bytes you pass in, the greater the accuracy of the
938prediction.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]939
940If you are intending to keep the file pointer open for use in libpng,
941you must ensure you don't read more than 8 bytes from the beginning
942of the file, and you also have to make a call to png_set_sig_bytes_read()
943with the number of bytes you read from the beginning. Libpng will
944then only check the bytes (if any) that your program didn't read.
945
946(*): If you are not using the standard I/O functions, you will need
947to replace them with custom functions. See the discussion under
948Customizing libpng.
949
950
951 FILE *fp = fopen(file_name, "rb");
952 if (!fp)
953 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]954 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]955 }
956 fread(header, 1, number, fp);
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]957 is_png = !png_sig_cmp(header, 0, number);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]958 if (!is_png)
959 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]960 return (NOT_PNG);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]961 }
962
963
964Next, png_struct and png_info need to be allocated and initialized. In
965order to ensure that the size of these structures is correct even with a
966dynamically linked libpng, there are functions to initialize and
967allocate the structures. We also pass the library version, optional
968pointers to error handling functions, and a pointer to a data struct for
969use by the error functions, if necessary (the pointer and functions can
970be NULL if the default error handlers are to be used). See the section
971on Changes to Libpng below regarding the old initialization functions.
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]972The structure allocation functions quietly return NULL if they fail to
973create the structure, so your application should check for that.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]974
975 png_structp png_ptr = png_create_read_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]976 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]977 user_error_fn, user_warning_fn);
978 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]979 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]980
981 png_infop info_ptr = png_create_info_struct(png_ptr);
982 if (!info_ptr)
983 {
984 png_destroy_read_struct(&png_ptr,
985 (png_infopp)NULL, (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]986 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]987 }
988
989 png_infop end_info = png_create_info_struct(png_ptr);
990 if (!end_info)
991 {
992 png_destroy_read_struct(&png_ptr, &info_ptr,
993 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]994 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]995 }
996
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]997If you want to use your own memory allocation routines,
998define PNG_USER_MEM_SUPPORTED and use
999png_create_read_struct_2() instead of png_create_read_struct():
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1000
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1001 png_structp png_ptr = png_create_read_struct_2
1002 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
1003 user_error_fn, user_warning_fn, (png_voidp)
1004 user_mem_ptr, user_malloc_fn, user_free_fn);
1005
1006The error handling routines passed to png_create_read_struct()
1007and the memory alloc/free routines passed to png_create_struct_2()
1008are only necessary if you are not using the libpng supplied error
1009handling and memory alloc/free functions.
1010
1011When libpng encounters an error, it expects to longjmp back
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1012to your routine. Therefore, you will need to call setjmp and pass
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1013your png_jmpbuf(png_ptr). If you read the file from different
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1014routines, you will need to update the jmpbuf field every time you enter
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1015a new routine that will call a png_*() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1016
1017See your documentation of setjmp/longjmp for your compiler for more
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1018information on setjmp/longjmp. See the discussion on libpng error
1019handling in the Customizing Libpng section below for more information
1020on the libpng error handling. If an error occurs, and libpng longjmp's
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1021back to your setjmp, you will want to call png_destroy_read_struct() to
1022free any memory.
1023
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1024 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1025 {
1026 png_destroy_read_struct(&png_ptr, &info_ptr,
1027 &end_info);
1028 fclose(fp);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]1029 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1030 }
1031
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1032If you would rather avoid the complexity of setjmp/longjmp issues,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]1033you can compile libpng with PNG_NO_SETJMP, in which case
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1034errors will result in a call to PNG_ABORT() which defaults to abort().
1035
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]1036You can #define PNG_ABORT() to a function that does something
1037more useful than abort(), as long as your function does not
1038return.
1039
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1040Now you need to set up the input code. The default for libpng is to
1041use the C function fread(). If you use this, you will need to pass a
1042valid FILE * in the function png_init_io(). Be sure that the file is
1043opened in binary mode. If you wish to handle reading data in another
1044way, you need not call the png_init_io() function, but you must then
1045implement the libpng I/O methods discussed in the Customizing Libpng
1046section below.
1047
1048 png_init_io(png_ptr, fp);
1049
1050If you had previously opened the file and read any of the signature from
1051the beginning in order to see if this was a PNG file, you need to let
1052libpng know that there are some bytes missing from the start of the file.
1053
1054 png_set_sig_bytes(png_ptr, number);
1055
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]1056You can change the zlib compression buffer size to be used while
1057reading compressed data with
1058
1059 png_set_compression_buffer_size(png_ptr, buffer_size);
1060
1061where the default size is 8192 bytes. Note that the buffer size
1062is changed immediately and the buffer is reallocated immediately,
1063instead of setting a flag to be acted upon later.
1064
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1065.SS Setting up callback code
1066
1067You can set up a callback function to handle any unknown chunks in the
1068input stream. You must supply the function
1069
1070 read_chunk_callback(png_ptr ptr,
1071 png_unknown_chunkp chunk);
1072 {
1073 /* The unknown chunk structure contains your
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1074 chunk data, along with similar data for any other
1075 unknown chunks: */
1076
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1077 png_byte name[5];
1078 png_byte *data;
1079 png_size_t size;
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1080
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1081 /* Note that libpng has already taken care of
1082 the CRC handling */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1083
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1084 /* put your code here. Search for your chunk in the
1085 unknown chunk structure, process it, and return one
1086 of the following: */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1087
1088 return (-n); /* chunk had an error */
1089 return (0); /* did not recognize */
1090 return (n); /* success */
1091 }
1092
1093(You can give your function another name that you like instead of
1094"read_chunk_callback")
1095
1096To inform libpng about your function, use
1097
1098 png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
1099 read_chunk_callback);
1100
1101This names not only the callback function, but also a user pointer that
1102you can retrieve with
1103
1104 png_get_user_chunk_ptr(png_ptr);
1105
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1106If you call the png_set_read_user_chunk_fn() function, then all unknown
1107chunks will be saved when read, in case your callback function will need
1108one or more of them. This behavior can be changed with the
1109png_set_keep_unknown_chunks() function, described below.
1110
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1111At this point, you can set up a callback function that will be
1112called after each row has been read, which you can use to control
1113a progress meter or the like. It's demonstrated in pngtest.c.
1114You must supply a function
1115
Glenn Randers-Pehrsone68f5a32001-05-14 09:20:53 -0500[diff] [blame]1116 void read_row_callback(png_ptr ptr, png_uint_32 row,
1117 int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1118 {
1119 /* put your code here */
1120 }
1121
1122(You can give it another name that you like instead of "read_row_callback")
1123
1124To inform libpng about your function, use
1125
1126 png_set_read_status_fn(png_ptr, read_row_callback);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1127
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1128.SS Unknown-chunk handling
1129
1130Now you get to set the way the library processes unknown chunks in the
1131input PNG stream. Both known and unknown chunks will be read. Normal
1132behavior is that known chunks will be parsed into information in
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1133various info_ptr members while unknown chunks will be discarded. This
1134behavior can be wasteful if your application will never use some known
1135chunk types. To change this, you can call:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1136
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]1137 png_set_keep_unknown_chunks(png_ptr, keep,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1138 chunk_list, num_chunks);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1139 keep - 0: default unknown chunk handling
1140 1: ignore; do not keep
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1141 2: keep only if safe-to-copy
1142 3: keep even if unsafe-to-copy
1143 You can use these definitions:
1144 PNG_HANDLE_CHUNK_AS_DEFAULT 0
1145 PNG_HANDLE_CHUNK_NEVER 1
1146 PNG_HANDLE_CHUNK_IF_SAFE 2
1147 PNG_HANDLE_CHUNK_ALWAYS 3
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1148 chunk_list - list of chunks affected (a byte string,
1149 five bytes per chunk, NULL or '\0' if
1150 num_chunks is 0)
1151 num_chunks - number of chunks affected; if 0, all
Glenn Randers-Pehrsondff799e2004-08-07 21:42:49 -0500[diff] [blame]1152 unknown chunks are affected. If nonzero,
1153 only the chunks in the list are affected
1154
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1155Unknown chunks declared in this way will be saved as raw data onto a
1156list of png_unknown_chunk structures. If a chunk that is normally
1157known to libpng is named in the list, it will be handled as unknown,
1158according to the "keep" directive. If a chunk is named in successive
1159instances of png_set_keep_unknown_chunks(), the final instance will
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1160take precedence. The IHDR and IEND chunks should not be named in
1161chunk_list; if they are, libpng will process them normally anyway.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1162
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1163Here is an example of the usage of png_set_keep_unknown_chunks(),
1164where the private "vpAg" chunk will later be processed by a user chunk
1165callback function:
1166
1167 png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
1168
1169 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1170 png_byte unused_chunks[]=
1171 {
1172 104, 73, 83, 84, (png_byte) '\0', /* hIST */
1173 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
1174 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
1175 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
1176 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
1177 116, 73, 77, 69, (png_byte) '\0', /* tIME */
1178 };
1179 #endif
1180
1181 ...
1182
1183 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1184 /* ignore all unknown chunks: */
1185 png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0);
1186 /* except for vpAg: */
1187 png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
1188 /* also ignore unused known chunks: */
1189 png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
1190 (int)sizeof(unused_chunks)/5);
1191 #endif
1192
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]1193.SS User limits
1194
1195The PNG specification allows the width and height of an image to be as
1196large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
1197Since very few applications really need to process such large images,
1198we have imposed an arbitrary 1-million limit on rows and columns.
1199Larger images will be rejected immediately with a png_error() call. If
1200you wish to override this limit, you can use
1201
1202 png_set_user_limits(png_ptr, width_max, height_max);
1203
1204to set your own limits, or use width_max = height_max = 0x7fffffffL
1205to allow all valid dimensions (libpng may reject some very large images
1206anyway because of potential buffer overflow conditions).
1207
1208You should put this statement after you create the PNG structure and
1209before calling png_read_info(), png_read_png(), or png_process_data().
1210If you need to retrieve the limits that are being applied, use
1211
1212 width_max = png_get_user_width_max(png_ptr);
1213 height_max = png_get_user_height_max(png_ptr);
1214
1215The PNG specification sets no limit on the number of ancillary chunks
1216allowed in a PNG datastream. You can impose a limit on the total number
1217of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
1218
1219 png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
1220
1221where 0x7fffffffL means unlimited. You can retrieve this limit with
1222
1223 chunk_cache_max = png_get_chunk_cache_max(png_ptr);
1224
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]1225This limit also applies to the number of buffers that can be allocated
1226by png_decompress_chunk() while decompressing iTXt, zTXt, and iCCP chunks.
1227
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]1228You can also set a limit on the amount of memory that a compressed chunk
1229other than IDAT can occupy, with
1230
1231 png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
1232
1233and you can retrieve the limit with
1234
1235 chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
1236
1237Any chunks that would cause either of these limits to be exceeded will
1238be ignored.
1239
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1240.SS The high-level read interface
1241
1242At this point there are two ways to proceed; through the high-level
1243read interface, or through a sequence of low-level read operations.
1244You can use the high-level interface if (a) you are willing to read
1245the entire image into memory, and (b) the input transformations
1246you want to do are limited to the following set:
1247
1248 PNG_TRANSFORM_IDENTITY No transformation
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1249 PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to
1250 8 bits
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1251 PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1252 PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
1253 samples to bytes
1254 PNG_TRANSFORM_PACKSWAP Change order of packed
1255 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1256 PNG_TRANSFORM_EXPAND Perform set_expand()
1257 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1258 PNG_TRANSFORM_SHIFT Normalize pixels to the
1259 sBIT depth
1260 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
1261 to BGRA
1262 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
1263 to AG
1264 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
1265 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1266 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson99708d52009-06-29 17:30:00 -0500[diff] [blame]1267 PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
1268 to RGB (or GA to RGBA)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1269
1270(This excludes setting a background color, doing gamma transformation,
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]1271quantizing, and setting filler.) If this is the case, simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1272
1273 png_read_png(png_ptr, info_ptr, png_transforms, NULL)
1274
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1275where png_transforms is an integer containing the bitwise OR of some
1276set of transformation flags. This call is equivalent to png_read_info(),
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1277followed the set of transformations indicated by the transform mask,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1278then png_read_image(), and finally png_read_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1279
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1280(The final parameter of this call is not yet used. Someday it might point
1281to transformation parameters required by some future input transform.)
1282
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]1283You must use png_transforms and not call any png_set_transform() functions
1284when you use png_read_png().
1285
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1286After you have called png_read_png(), you can retrieve the image data
1287with
1288
1289 row_pointers = png_get_rows(png_ptr, info_ptr);
1290
1291where row_pointers is an array of pointers to the pixel data for each row:
1292
1293 png_bytep row_pointers[height];
1294
1295If you know your image size and pixel size ahead of time, you can allocate
1296row_pointers prior to calling png_read_png() with
1297
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1298 if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]1299 png_error (png_ptr,
1300 "Image is too tall to process in memory");
1301 if (width > PNG_UINT_32_MAX/pixel_size)
1302 png_error (png_ptr,
1303 "Image is too wide to process in memory");
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1304 row_pointers = png_malloc(png_ptr,
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1305 height*png_sizeof(png_bytep));
1306 for (int i=0; i<height, i++)
1307 row_pointers[i]=NULL; /* security precaution */
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1308 for (int i=0; i<height, i++)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1309 row_pointers[i]=png_malloc(png_ptr,
1310 width*pixel_size);
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]1311 png_set_rows(png_ptr, info_ptr, &row_pointers);
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1312
1313Alternatively you could allocate your image in one big block and define
1314row_pointers[i] to point into the proper places in your block.
1315
1316If you use png_set_rows(), the application is responsible for freeing
1317row_pointers (and row_pointers[i], if they were separately allocated).
1318
1319If you don't allocate row_pointers ahead of time, png_read_png() will
1320do it, and it'll be free'ed when you call png_destroy_*().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1321
1322.SS The low-level read interface
1323
1324If you are going the low-level route, you are now ready to read all
1325the file information up to the actual image data. You do this with a
1326call to png_read_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1327
1328 png_read_info(png_ptr, info_ptr);
1329
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1330This will process all chunks up to but not including the image data.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1331
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1332.SS Querying the info structure
1333
1334Functions are used to get the information from the info_ptr once it
1335has been read. Note that these fields may not be completely filled
1336in until png_read_end() has read the chunk data following the image.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1337
1338 png_get_IHDR(png_ptr, info_ptr, &width, &height,
1339 &bit_depth, &color_type, &interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1340 &compression_type, &filter_method);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1341
1342 width - holds the width of the image
1343 in pixels (up to 2^31).
1344 height - holds the height of the image
1345 in pixels (up to 2^31).
1346 bit_depth - holds the bit depth of one of the
1347 image channels. (valid values are
1348 1, 2, 4, 8, 16 and depend also on
1349 the color_type. See also
1350 significant bits (sBIT) below).
1351 color_type - describes which color/alpha channels
1352 are present.
1353 PNG_COLOR_TYPE_GRAY
1354 (bit depths 1, 2, 4, 8, 16)
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1355 PNG_COLOR_TYPE_GRAY_ALPHA
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1356 (bit depths 8, 16)
1357 PNG_COLOR_TYPE_PALETTE
1358 (bit depths 1, 2, 4, 8)
1359 PNG_COLOR_TYPE_RGB
1360 (bit_depths 8, 16)
1361 PNG_COLOR_TYPE_RGB_ALPHA
1362 (bit_depths 8, 16)
1363
1364 PNG_COLOR_MASK_PALETTE
1365 PNG_COLOR_MASK_COLOR
1366 PNG_COLOR_MASK_ALPHA
1367
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1368 filter_method - (must be PNG_FILTER_TYPE_BASE
1369 for PNG 1.0, and can also be
1370 PNG_INTRAPIXEL_DIFFERENCING if
1371 the PNG datastream is embedded in
1372 a MNG-1.0 datastream)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1373 compression_type - (must be PNG_COMPRESSION_TYPE_BASE
1374 for PNG 1.0)
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1375 interlace_type - (PNG_INTERLACE_NONE or
1376 PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1377
1378 Any or all of interlace_type, compression_type, or
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1379 filter_method can be NULL if you are
1380 not interested in their values.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1381
Glenn Randers-Pehrson0bfb58f2009-09-30 23:07:22 -0500[diff] [blame]1382 Note that png_get_IHDR() returns 32-bit data into
1383 the application's width and height variables.
1384 This is an unsafe situation if these are 16-bit
1385 variables. In such situations, the
1386 png_get_image_width() and png_get_image_height()
1387 functions described below are safer.
1388
1389 width = png_get_image_width(png_ptr,
1390 info_ptr);
1391 height = png_get_image_height(png_ptr,
1392 info_ptr);
1393 bit_depth = png_get_bit_depth(png_ptr,
1394 info_ptr);
1395 color_type = png_get_color_type(png_ptr,
1396 info_ptr);
1397 filter_method = png_get_filter_type(png_ptr,
1398 info_ptr);
1399 compression_type = png_get_compression_type(png_ptr,
1400 info_ptr);
1401 interlace_type = png_get_interlace_type(png_ptr,
1402 info_ptr);
1403
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1404 channels = png_get_channels(png_ptr, info_ptr);
1405 channels - number of channels of info for the
1406 color type (valid values are 1 (GRAY,
1407 PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
1408 4 (RGB_ALPHA or RGB + filler byte))
1409 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
1410 rowbytes - number of bytes needed to hold a row
1411
1412 signature = png_get_signature(png_ptr, info_ptr);
1413 signature - holds the signature read from the
1414 file (if any). The data is kept in
1415 the same offset it would be if the
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1416 whole signature were read (i.e. if an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1417 application had already read in 4
1418 bytes of signature before starting
1419 libpng, the remaining 4 bytes would
1420 be in signature[4] through signature[7]
1421 (see png_set_sig_bytes())).
1422
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1423These are also important, but their validity depends on whether the chunk
1424has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
1425png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
1426data has been read, or zero if it is missing. The parameters to the
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1427png_get_<chunk> are set directly if they are simple data types, or a
1428pointer into the info_ptr is returned for any complex types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1429
1430 png_get_PLTE(png_ptr, info_ptr, &palette,
1431 &num_palette);
1432 palette - the palette for the file
1433 (array of png_color)
1434 num_palette - number of entries in the palette
1435
1436 png_get_gAMA(png_ptr, info_ptr, &gamma);
1437 gamma - the gamma the file is written
1438 at (PNG_INFO_gAMA)
1439
1440 png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
1441 srgb_intent - the rendering intent (PNG_INFO_sRGB)
1442 The presence of the sRGB chunk
1443 means that the pixel data is in the
1444 sRGB color space. This chunk also
1445 implies specific values of gAMA and
1446 cHRM.
1447
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1448 png_get_iCCP(png_ptr, info_ptr, &name,
1449 &compression_type, &profile, &proflen);
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1450 name - The profile name.
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1451 compression - The compression type; always
1452 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
1453 You may give NULL to this argument to
1454 ignore it.
1455 profile - International Color Consortium color
1456 profile data. May contain NULs.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1457 proflen - length of profile data in bytes.
1458
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1459 png_get_sBIT(png_ptr, info_ptr, &sig_bit);
1460 sig_bit - the number of significant bits for
1461 (PNG_INFO_sBIT) each of the gray,
1462 red, green, and blue channels,
1463 whichever are appropriate for the
1464 given color type (png_color_16)
1465
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]1466 png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
1467 &num_trans, &trans_color);
1468 trans_alpha - array of alpha (transparency)
1469 entries for palette (PNG_INFO_tRNS)
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1470 trans_color - graylevel or color sample values of
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]1471 the single transparent color for
1472 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1473 num_trans - number of transparent entries
1474 (PNG_INFO_tRNS)
1475
1476 png_get_hIST(png_ptr, info_ptr, &hist);
1477 (PNG_INFO_hIST)
1478 hist - histogram of palette (array of
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1479 png_uint_16)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1480
1481 png_get_tIME(png_ptr, info_ptr, &mod_time);
1482 mod_time - time image was last modified
1483 (PNG_VALID_tIME)
1484
1485 png_get_bKGD(png_ptr, info_ptr, &background);
1486 background - background color (PNG_VALID_bKGD)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1487 valid 16-bit red, green and blue
1488 values, regardless of color_type
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1489
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1490 num_comments = png_get_text(png_ptr, info_ptr,
1491 &text_ptr, &num_text);
1492 num_comments - number of comments
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1493 text_ptr - array of png_text holding image
1494 comments
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1495 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1496 on "text" PNG_TEXT_COMPRESSION_NONE
1497 PNG_TEXT_COMPRESSION_zTXt
1498 PNG_ITXT_COMPRESSION_NONE
1499 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1500 text_ptr[i].key - keyword for comment. Must contain
1501 1-79 characters.
1502 text_ptr[i].text - text comments for current
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]1503 keyword. Can be empty.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1504 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1505 after decompression, 0 for iTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1506 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1507 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1508 text_ptr[i].lang - language of comment (empty
1509 string for unknown).
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]1510 text_ptr[i].lang_key - keyword in UTF-8
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1511 (empty string for unknown).
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]1512 Note that the itxt_length, lang, and lang_key
1513 members of the text_ptr structure only exist
1514 when the library is built with iTXt chunk support.
1515
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1516 num_text - number of comments (same as
1517 num_comments; you can put NULL here
1518 to avoid the duplication)
1519 Note while png_set_text() will accept text, language,
1520 and translated keywords that can be NULL pointers, the
1521 structure returned by png_get_text will always contain
1522 regular zero-terminated C strings. They might be
1523 empty strings but they will never be NULL pointers.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1524
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1525 num_spalettes = png_get_sPLT(png_ptr, info_ptr,
1526 &palette_ptr);
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1527 palette_ptr - array of palette structures holding
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1528 contents of one or more sPLT chunks
1529 read.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1530 num_spalettes - number of sPLT chunks read.
1531
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1532 png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1533 &unit_type);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1534 offset_x - positive offset from the left edge
1535 of the screen
1536 offset_y - positive offset from the top edge
1537 of the screen
1538 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
1539
1540 png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1541 &unit_type);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1542 res_x - pixels/unit physical resolution in
1543 x direction
1544 res_y - pixels/unit physical resolution in
1545 x direction
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1546 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1547 PNG_RESOLUTION_METER
1548
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1549 png_get_sCAL(png_ptr, info_ptr, &unit, &width,
1550 &height)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1551 unit - physical scale units (an integer)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1552 width - width of a pixel in physical scale units
1553 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1554 (width and height are doubles)
1555
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1556 png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
1557 &height)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1558 unit - physical scale units (an integer)
1559 width - width of a pixel in physical scale units
1560 height - height of a pixel in physical scale units
1561 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1562
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1563 num_unknown_chunks = png_get_unknown_chunks(png_ptr,
1564 info_ptr, &unknowns)
1565 unknowns - array of png_unknown_chunk
1566 structures holding unknown chunks
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1567 unknowns[i].name - name of unknown chunk
1568 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1569 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1570 unknowns[i].location - position of chunk in file
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1571
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1572 The value of "i" corresponds to the order in which the
1573 chunks were read from the PNG file or inserted with the
1574 png_set_unknown_chunks() function.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1575
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1576The data from the pHYs chunk can be retrieved in several convenient
1577forms:
1578
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1579 res_x = png_get_x_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1580 info_ptr)
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1581 res_y = png_get_y_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1582 info_ptr)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1583 res_x_and_y = png_get_pixels_per_meter(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1584 info_ptr)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1585 res_x = png_get_x_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1586 info_ptr)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1587 res_y = png_get_y_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1588 info_ptr)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1589 res_x_and_y = png_get_pixels_per_inch(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1590 info_ptr)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1591 aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1592 info_ptr)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1593
1594 (Each of these returns 0 [signifying "unknown"] if
1595 the data is not present or if res_x is 0;
1596 res_x_and_y is 0 if res_x != res_y)
1597
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1598The data from the oFFs chunk can be retrieved in several convenient
1599forms:
1600
1601 x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
1602 y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
1603 x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
1604 y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
1605
1606 (Each of these returns 0 [signifying "unknown" if both
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1607 x and y are 0] if the data is not present or if the
1608 chunk is present but the unit is the pixel)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1609
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1610For more information, see the png_info definition in png.h and the
1611PNG specification for chunk contents. Be careful with trusting
1612rowbytes, as some of the transformations could increase the space
1613needed to hold a row (expand, filler, gray_to_rgb, etc.).
1614See png_read_update_info(), below.
1615
1616A quick word about text_ptr and num_text. PNG stores comments in
1617keyword/text pairs, one pair per chunk, with no limit on the number
1618of text chunks, and a 2^31 byte limit on their size. While there are
1619suggested keywords, there is no requirement to restrict the use to these
1620strings. It is strongly suggested that keywords and text be sensible
1621to humans (that's the point), so don't use abbreviations. Non-printing
1622symbols are not allowed. See the PNG specification for more details.
1623There is also no requirement to have text after the keyword.
1624
1625Keywords should be limited to 79 Latin-1 characters without leading or
1626trailing spaces, but non-consecutive spaces are allowed within the
1627keyword. It is possible to have the same keyword any number of times.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1628The text_ptr is an array of png_text structures, each holding a
1629pointer to a language string, a pointer to a keyword and a pointer to
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1630a text string. The text string, language code, and translated
1631keyword may be empty or NULL pointers. The keyword/text
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1632pairs are put into the array in the order that they are received.
1633However, some or all of the text chunks may be after the image, so, to
1634make sure you have read all the text chunks, don't mess with these
1635until after you read the stuff after the image. This will be
1636mentioned again below in the discussion that goes with png_read_end().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1637
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1638.SS Input transformations
1639
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1640After you've read the header information, you can set up the library
1641to handle any special transformations of the image data. The various
1642ways to transform the data will be described in the order that they
1643should occur. This is important, as some of these change the color
1644type and/or bit depth of the data, and some others only work on
1645certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1646checks 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]1647make sure to only enable a transformation if it will be valid for the
1648data. For example, don't swap red and blue on grayscale data.
1649
1650The colors used for the background and transparency values should be
1651supplied in the same format/depth as the current image data. They
1652are stored in the same format/depth as the image data in a bKGD or tRNS
1653chunk, so this is what libpng expects for this data. The colors are
1654transformed to keep in sync with the image data when an application
1655calls the png_read_update_info() routine (see below).
1656
1657Data will be decoded into the supplied row buffers packed into bytes
1658unless the library has been told to transform it into another format.
1659For example, 4 bit/pixel paletted or grayscale data will be returned
16602 pixels/byte with the leftmost pixel in the high-order bits of the
1661byte, unless png_set_packing() is called. 8-bit RGB data will be stored
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1662in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
Glenn Randers-Pehrson86f88dd2010-03-08 21:28:21 -0600[diff] [blame]1663%10%in RGB RGB RGB format unless png_set_filler()
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1664is called to insert filler bytes, either before or after each RGB triplet.
166516-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
1666byte of the color value first, unless png_set_strip_16() is called to
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]1667transform it to regular RGB RGB triplets, or png_set_filler() or
1668png_set_add alpha() is called to insert filler bytes, either before or
1669after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
1670be modified with
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1671png_set_filler(), png_set_add_alpha(), or png_set_strip_16().
Glenn Randers-Pehrson86f88dd2010-03-08 21:28:21 -0600[diff] [blame]1672%10%png_set_filler() or png_set_strip_16().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1673
1674The following code transforms grayscale images of less than 8 to 8 bits,
1675changes paletted images to RGB, and adds a full alpha channel if there is
1676transparency information in a tRNS chunk. This is most useful on
1677grayscale images with bit depths of 2 or 4 or if there is a multiple-image
1678viewing application that wishes to treat all images in the same way.
1679
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]1680 if (color_type == PNG_COLOR_TYPE_PALETTE)
1681 png_set_palette_to_rgb(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1682
1683 if (color_type == PNG_COLOR_TYPE_GRAY &&
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]1684 bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
Glenn Randers-Pehrson86f88dd2010-03-08 21:28:21 -0600[diff] [blame]1685%10% bit_depth < 8) png_set_gray_1_2_4_to_8(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1686
1687 if (png_get_valid(png_ptr, info_ptr,
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]1688 PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
1689
1690These three functions are actually aliases for png_set_expand(), added
1691in libpng version 1.0.4, with the function names expanded to improve code
1692readability. In some future version they may actually do different
1693things.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1694
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]1695As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
1696added. It expands the sample depth without changing tRNS to alpha.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1697
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]1698As of libpng version 1.5.0beta26, not all possible expansions are supported.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1699
1700In the following table, the 01 means grayscale with depth<8, 31 means
1701indexed with depth<8, other numerals represent the color type, "T" means
1702the tRNS chunk is present, A means an alpha channel is present, and O
1703means tRNS or alpha is present but all pixels in the image are opaque.
1704
1705 FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
1706 TO
1707 01 -
1708 31 -
1709 0 1 -
1710 0T -
1711 0O -
1712 2 GX -
1713 2T -
1714 2O -
1715 3 1 -
1716 3T -
1717 3O -
1718 4A T -
1719 4O -
1720 6A GX TX TX -
1721 6O GX TX -
1722
1723Within the matrix,
1724 "-" means the transformation is not supported.
1725 "X" means the transformation is obtained by png_set_expand().
1726 "1" means the transformation is obtained by
1727 png_set_expand_gray_1_2_4_to_8
1728 "G" means the transformation is obtained by
1729 png_set_gray_to_rgb().
1730 "P" means the transformation is obtained by
1731 png_set_expand_palette_to_rgb().
1732 "T" means the transformation is obtained by
1733 png_set_tRNS_to_alpha().
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]1734
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1735PNG can have files with 16 bits per channel. If you only can handle
17368 bits per channel, this will strip the pixels down to 8 bit.
1737
1738 if (bit_depth == 16)
1739 png_set_strip_16(png_ptr);
1740
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1741If, for some reason, you don't need the alpha channel on an image,
1742and you want to remove it rather than combining it with the background
1743(but the image author certainly had in mind that you *would* combine
1744it with the background, so that's what you should probably do):
1745
1746 if (color_type & PNG_COLOR_MASK_ALPHA)
1747 png_set_strip_alpha(png_ptr);
1748
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1749In PNG files, the alpha channel in an image
1750is the level of opacity. If you need the alpha channel in an image to
1751be the level of transparency instead of opacity, you can invert the
1752alpha channel (or the tRNS chunk data) after it's read, so that 0 is
1753fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
1754images) is fully transparent, with
1755
1756 png_set_invert_alpha(png_ptr);
1757
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1758PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
1759they can, resulting in, for example, 8 pixels per byte for 1 bit
1760files. This code expands to 1 pixel per byte without changing the
1761values of the pixels:
1762
1763 if (bit_depth < 8)
1764 png_set_packing(png_ptr);
1765
1766PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
1767stored in a PNG image have been "scaled" or "shifted" up to the next
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]1768higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
1769to 8 bits/sample in the range [0, 255]). However, it is also possible
1770to convert the PNG pixel data back to the original bit depth of the
1771image. This call reduces the pixels back down to the original bit depth:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1772
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]1773 png_color_8p sig_bit;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1774
1775 if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
1776 png_set_shift(png_ptr, sig_bit);
1777
1778PNG files store 3-color pixels in red, green, blue order. This code
1779changes the storage of the pixels to blue, green, red:
1780
1781 if (color_type == PNG_COLOR_TYPE_RGB ||
1782 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
1783 png_set_bgr(png_ptr);
1784
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]1785PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
1786into 4 or 8 bytes for windowing systems that need them in this format:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1787
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]1788 if (color_type == PNG_COLOR_TYPE_RGB)
1789 png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1790
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]1791where "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]1792either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
1793you want the filler before the RGB or after. This transformation
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]1794does not affect images that already have full alpha channels. To add an
1795opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
1796will generate RGBA pixels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1797
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1798Note that png_set_filler() does not change the color type. If you want
1799to do that, you can add a true alpha channel with
1800
1801 if (color_type == PNG_COLOR_TYPE_RGB ||
1802 color_type == PNG_COLOR_TYPE_GRAY)
1803 png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
1804
1805where "filler" contains the alpha value to assign to each pixel.
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]1806This function was added in libpng-1.2.7.
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1807
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1808If you are reading an image with an alpha channel, and you need the
1809data as ARGB instead of the normal PNG format RGBA:
1810
1811 if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
1812 png_set_swap_alpha(png_ptr);
1813
1814For some uses, you may want a grayscale image to be represented as
1815RGB. This code will do that conversion:
1816
1817 if (color_type == PNG_COLOR_TYPE_GRAY ||
1818 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
1819 png_set_gray_to_rgb(png_ptr);
1820
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1821Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1822with alpha.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1823
1824 if (color_type == PNG_COLOR_TYPE_RGB ||
1825 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1826 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1827 int red_weight, int green_weight);
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1828
1829 error_action = 1: silently do the conversion
1830 error_action = 2: issue a warning if the original
1831 image has any pixel where
1832 red != green or red != blue
1833 error_action = 3: issue an error and abort the
1834 conversion if the original
1835 image has any pixel where
1836 red != green or red != blue
1837
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1838 red_weight: weight of red component times 100000
1839 green_weight: weight of green component times 100000
1840 If either weight is negative, default
1841 weights (21268, 71514) are used.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1842
1843If you have set error_action = 1 or 2, you can
1844later check whether the image really was gray, after processing
1845the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
1846It will return a png_byte that is zero if the image was gray or
18471 if there were any non-gray pixels. bKGD and sBIT data
1848will be silently converted to grayscale, using the green channel
1849data, regardless of the error_action setting.
1850
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1851With red_weight+green_weight<=100000,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1852the normalized graylevel is computed:
1853
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1854 int rw = red_weight * 65536;
1855 int gw = green_weight * 65536;
1856 int bw = 65536 - (rw + gw);
1857 gray = (rw*red + gw*green + bw*blue)/65536;
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1858
1859The default values approximate those recommended in the Charles
1860Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]1861Copyright (c) 1998-01-04 Charles Poynton <poynton at inforamp.net>
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1862
1863 Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
1864
1865Libpng approximates this with
1866
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1867 Y = 0.21268 * R + 0.7151 * G + 0.07217 * B
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1868
1869which can be expressed with integers as
1870
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1871 Y = (6969 * R + 23434 * G + 2365 * B)/32768
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1872
1873The calculation is done in a linear colorspace, if the image gamma
1874is known.
1875
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]1876If you have a grayscale and you are using png_set_expand_depth(),
1877png_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]1878a higher bit-depth, you must either supply the background color as a gray
1879value at the original file bit-depth (need_expand = 1) or else supply the
1880background color as an RGB triplet at the final, expanded bit depth
1881(need_expand = 0). Similarly, if you are reading a paletted image, you
1882must either supply the background color as a palette index (need_expand = 1)
1883or 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]1884
1885 png_color_16 my_background;
1886 png_color_16p image_background;
1887
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]1888 if (png_get_bKGD(png_ptr, info_ptr, &image_background))
1889 png_set_background(png_ptr, image_background,
1890 PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1891 else
1892 png_set_background(png_ptr, &my_background,
1893 PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
1894
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]1895The png_set_background() function tells libpng to composite images
1896with alpha or simple transparency against the supplied background
1897color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
1898you may use this color, or supply another color more suitable for
1899the current display (e.g., the background color from a web page). You
1900need to tell libpng whether the color is in the gamma space of the
1901display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
1902(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
1903that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
1904know why anyone would use this, but it's here).
1905
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1906To properly display PNG images on any kind of system, the application needs
1907to know what the display gamma is. Ideally, the user will know this, and
1908the application will allow them to set it. One method of allowing the user
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]1909to set the display gamma separately for each system is to check for a
1910SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
1911correctly set.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1912
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]1913Note that display_gamma is the overall gamma correction required to produce
1914pleasing results, which depends on the lighting conditions in the surrounding
1915environment. In a dim or brightly lit room, no compensation other than
1916the physical gamma exponent of the monitor is needed, while in a dark room
1917a slightly smaller exponent is better.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1918
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]1919 double gamma, screen_gamma;
1920
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1921 if (/* We have a user-defined screen
1922 gamma value */)
1923 {
1924 screen_gamma = user_defined_screen_gamma;
1925 }
1926 /* One way that applications can share the same
1927 screen gamma value */
1928 else if ((gamma_str = getenv("SCREEN_GAMMA"))
1929 != NULL)
1930 {
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]1931 screen_gamma = (double)atof(gamma_str);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1932 }
1933 /* If we don't have another value */
1934 else
1935 {
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1936 screen_gamma = 2.2; /* A good guess for a
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1937 PC monitor in a bright office or a dim room */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1938 screen_gamma = 2.0; /* A good guess for a
1939 PC monitor in a dark room */
1940 screen_gamma = 1.7 or 1.0; /* A good
1941 guess for Mac systems */
1942 }
1943
1944The png_set_gamma() function handles gamma transformations of the data.
1945Pass both the file gamma and the current screen_gamma. If the file does
1946not 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]1947it 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]1948that file gammas are inverted from screen gammas. See the discussions
1949on gamma in the PNG specification for an excellent description of what
1950gamma is, and why all applications should support it. It is strongly
1951recommended that PNG viewers support gamma correction.
1952
1953 if (png_get_gAMA(png_ptr, info_ptr, &gamma))
1954 png_set_gamma(png_ptr, screen_gamma, gamma);
1955 else
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1956 png_set_gamma(png_ptr, screen_gamma, 0.45455);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1957
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]1958If you need to reduce an RGB file to a paletted file, or if a paletted
1959file has more entries then will fit on your screen, png_set_quantize()
Glenn Randers-Pehrson862cb202010-04-16 22:12:51 -0500[diff] [blame]1960will do that. Note that this is a simple match quantization that merely
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]1961finds the closest color available. This should work fairly well with
1962optimized palettes, and fairly badly with linear color cubes. If you
1963pass a palette that is larger then maximum_colors, the file will
1964reduce the number of colors in the palette so it will fit into
1965maximum_colors. If there is a histogram, it will use it to make
1966more intelligent choices when reducing the palette. If there is no
1967histogram, it may not do as good a job.
1968
1969 if (color_type & PNG_COLOR_MASK_COLOR)
1970 {
1971 if (png_get_valid(png_ptr, info_ptr,
1972 PNG_INFO_PLTE))
1973 {
1974 png_uint_16p histogram = NULL;
1975
1976 png_get_hIST(png_ptr, info_ptr,
1977 &histogram);
1978 png_set_quantize(png_ptr, palette, num_palette,
1979 max_screen_colors, histogram, 1);
1980 }
1981 else
1982 {
1983 png_color std_color_cube[MAX_SCREEN_COLORS] =
1984 { ... colors ... };
1985
1986 png_set_quantize(png_ptr, std_color_cube,
1987 MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
1988 NULL,0);
1989 }
1990 }
1991
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1992PNG files describe monochrome as black being zero and white being one.
1993The following code will reverse this (make black be one and white be
1994zero):
1995
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]1996 if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
1997 png_set_invert_mono(png_ptr);
1998
1999This function can also be used to invert grayscale and gray-alpha images:
2000
2001 if (color_type == PNG_COLOR_TYPE_GRAY ||
2002 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2003 png_set_invert_mono(png_ptr);
2004
2005PNG files store 16 bit pixels in network byte order (big-endian,
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2006ie. most significant bits first). This code changes the storage to the
2007other way (little-endian, i.e. least significant bits first, the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2008way PCs store them):
2009
2010 if (bit_depth == 16)
2011 png_set_swap(png_ptr);
2012
2013If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
2014need to change the order the pixels are packed into bytes, you can use:
2015
2016 if (bit_depth < 8)
2017 png_set_packswap(png_ptr);
2018
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2019Finally, you can write your own transformation function if none of
2020the existing ones meets your needs. This is done by setting a callback
2021with
2022
2023 png_set_read_user_transform_fn(png_ptr,
2024 read_transform_fn);
2025
2026You must supply the function
2027
2028 void read_transform_fn(png_ptr ptr, row_info_ptr
2029 row_info, png_bytep data)
2030
2031See pngtest.c for a working example. Your function will be called
2032after all of the other transformations have been processed.
2033
2034You can also set up a pointer to a user structure for use by your
2035callback function, and you can inform libpng that your transform
2036function will change the number of channels or bit depth with the
2037function
2038
2039 png_set_user_transform_info(png_ptr, user_ptr,
2040 user_depth, user_channels);
2041
2042The user's application, not libpng, is responsible for allocating and
2043freeing any memory required for the user structure.
2044
2045You can retrieve the pointer via the function
2046png_get_user_transform_ptr(). For example:
2047
2048 voidp read_user_transform_ptr =
2049 png_get_user_transform_ptr(png_ptr);
2050
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2051The last thing to handle is interlacing; this is covered in detail below,
2052but you must call the function here if you want libpng to handle expansion
2053of the interlaced image.
2054
2055 number_of_passes = png_set_interlace_handling(png_ptr);
2056
2057After setting the transformations, libpng can update your png_info
2058structure to reflect any transformations you've requested with this
2059call. This is most useful to update the info structure's rowbytes
2060field so you can use it to allocate your image memory. This function
2061will also update your palette with the correct screen_gamma and
2062background if these have been given with the calls above.
2063
2064 png_read_update_info(png_ptr, info_ptr);
2065
2066After you call png_read_update_info(), you can allocate any
2067memory you need to hold the image. The row data is simply
2068raw byte data for all forms of images. As the actual allocation
2069varies among applications, no example will be given. If you
2070are allocating one large chunk, you will need to build an
2071array of pointers to each row, as it will be needed for some
2072of the functions below.
2073
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2074.SS Reading image data
2075
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2076After you've allocated memory, you can read the image data.
2077The simplest way to do this is in one function call. If you are
2078allocating enough memory to hold the whole image, you can just
2079call png_read_image() and libpng will read in all the image data
2080and put it in the memory area supplied. You will need to pass in
2081an array of pointers to each row.
2082
2083This function automatically handles interlacing, so you don't need
2084to call png_set_interlace_handling() or call this function multiple
2085times, or any of that other stuff necessary with png_read_rows().
2086
2087 png_read_image(png_ptr, row_pointers);
2088
2089where row_pointers is:
2090
2091 png_bytep row_pointers[height];
2092
2093You can point to void or char or whatever you use for pixels.
2094
2095If you don't want to read in the whole image at once, you can
2096use png_read_rows() instead. If there is no interlacing (check
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2097interlace_type == PNG_INTERLACE_NONE), this is simple:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2098
2099 png_read_rows(png_ptr, row_pointers, NULL,
2100 number_of_rows);
2101
2102where row_pointers is the same as in the png_read_image() call.
2103
2104If 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]2105a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2106
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2107 png_bytep row_pointer = row;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2108 png_read_row(png_ptr, row_pointer, NULL);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2109
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2110If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
2111get somewhat harder. The only current (PNG Specification version 1.2)
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2112interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2113is a somewhat complicated 2D interlace scheme, known as Adam7, that
2114breaks down an image into seven smaller images of varying size, based
2115on an 8x8 grid.
2116
2117libpng can fill out those images or it can give them to you "as is".
2118If you want them filled out, there are two ways to do that. The one
2119mentioned in the PNG specification is to expand each pixel to cover
2120those pixels that have not been read yet (the "rectangle" method).
2121This results in a blocky image for the first pass, which gradually
2122smooths out as more pixels are read. The other method is the "sparkle"
2123method, where pixels are drawn only in their final locations, with the
2124rest of the image remaining whatever colors they were initialized to
2125before the start of the read. The first method usually looks better,
2126but tends to be slower, as there are more pixels to put in the rows.
2127
2128If you don't want libpng to handle the interlacing details, just call
2129png_read_rows() seven times to read in all seven images. Each of the
2130images is a valid image by itself, or they can all be combined on an
21318x8 grid to form a single image (although if you intend to combine them
2132you would be far better off using the libpng interlace handling).
2133
2134The first pass will return an image 1/8 as wide as the entire image
2135(every 8th column starting in column 0) and 1/8 as high as the original
2136(every 8th row starting in row 0), the second will be 1/8 as wide
2137(starting in column 4) and 1/8 as high (also starting in row 0). The
2138third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
21391/8 as high (every 8th row starting in row 4), and the fourth pass will
2140be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
2141and every 4th row starting in row 0). The fifth pass will return an
2142image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2),
2143while the sixth pass will be 1/2 as wide and 1/2 as high as the original
2144(starting in column 1 and row 0). The seventh and final pass will be as
2145wide as the original, and 1/2 as high, containing all of the odd
2146numbered scanlines. Phew!
2147
2148If you want libpng to expand the images, call this before calling
2149png_start_read_image() or png_read_update_info():
2150
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2151 if (interlace_type == PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2152 number_of_passes
2153 = png_set_interlace_handling(png_ptr);
2154
2155This will return the number of passes needed. Currently, this
2156is seven, but may change if another interlace type is added.
2157This function can be called even if the file is not interlaced,
2158where it will return one pass.
2159
2160If you are not going to display the image after each pass, but are
2161going to wait until the entire image is read in, use the sparkle
2162effect. This effect is faster and the end result of either method
2163is exactly the same. If you are planning on displaying the image
2164after each pass, the "rectangle" effect is generally considered the
2165better looking one.
2166
2167If you only want the "sparkle" effect, just call png_read_rows() as
2168normal, with the third parameter NULL. Make sure you make pass over
2169the image number_of_passes times, and you don't change the data in the
2170rows between calls. You can change the locations of the data, just
2171not the data. Each pass only writes the pixels appropriate for that
2172pass, and assumes the data from previous passes is still valid.
2173
2174 png_read_rows(png_ptr, row_pointers, NULL,
2175 number_of_rows);
2176
2177If you only want the first effect (the rectangles), do the same as
2178before except pass the row buffer in the third parameter, and leave
2179the second parameter NULL.
2180
2181 png_read_rows(png_ptr, NULL, row_pointers,
2182 number_of_rows);
2183
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2184.SS Finishing a sequential read
2185
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]2186After you are finished reading the image through the
2187low-level interface, you can finish reading the file. If you are
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2188interested in comments or time, which may be stored either before or
2189after the image data, you should pass the separate png_info struct if
2190you want to keep the comments from before and after the image
2191separate. If you are not interested, you can pass NULL.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2192
2193 png_read_end(png_ptr, end_info);
2194
2195When you are done, you can free all memory allocated by libpng like this:
2196
2197 png_destroy_read_struct(&png_ptr, &info_ptr,
2198 &end_info);
2199
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2200It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2201point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2202
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2203 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2204 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2205 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2206 more of
2207 PNG_FREE_PLTE, PNG_FREE_TRNS,
2208 PNG_FREE_HIST, PNG_FREE_ICCP,
2209 PNG_FREE_PCAL, PNG_FREE_ROWS,
2210 PNG_FREE_SCAL, PNG_FREE_SPLT,
2211 PNG_FREE_TEXT, PNG_FREE_UNKN,
2212 or simply PNG_FREE_ALL
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2213 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2214 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2215
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2216This function may be safely called when the relevant storage has
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]2217already been freed, or has not yet been allocated, or was allocated
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2218by the user and not by libpng, and will in those cases do nothing.
2219The "seq" parameter is ignored if only one item of the selected data
2220type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
2221are allowed for the data type identified in the mask, such as text or
2222sPLT, 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]2223
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2224The default behavior is only to free data that was allocated internally
2225by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2226or so that it will free data that was allocated by the user with png_malloc()
2227or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2228
2229 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2230 mask - which data elements are affected
2231 same choices as in png_free_data()
2232 freer - one of
2233 PNG_DESTROY_WILL_FREE_DATA
2234 PNG_SET_WILL_FREE_DATA
2235 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2236
2237This function only affects data that has already been allocated.
2238You can call this function after reading the PNG data but before calling
2239any png_set_*() functions, to control whether the user or the png_set_*()
2240function is responsible for freeing any existing data that might be present,
2241and again after the png_set_*() functions to control whether the user
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2242or png_destroy_*() is supposed to free the data. When the user assumes
2243responsibility for libpng-allocated data, the application must use
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2244png_free() to free it, and when the user transfers responsibility to libpng
2245for data that the user has allocated, the user must have used png_malloc()
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]2246or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2247
2248If you allocated your row_pointers in a single block, as suggested above in
2249the description of the high level read interface, you must not transfer
2250responsibility for freeing it to the png_set_rows or png_read_destroy function,
2251because they would also try to free the individual row_pointers[i].
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2252
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2253If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
2254separately, do not transfer responsibility for freeing text_ptr to libpng,
2255because when libpng fills a png_text structure it combines these members with
2256the key member, and png_free_data() will free only text_ptr.key. Similarly,
2257if you transfer responsibility for free'ing text_ptr from libpng to your
2258application, your application must not separately free those members.
2259
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2260The png_free_data() function will turn off the "valid" flag for anything
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2261it frees. If you need to turn the flag off for a chunk that was freed by
2262your application instead of by libpng, you can use
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2263
2264 png_set_invalid(png_ptr, info_ptr, mask);
2265 mask - identifies the chunks to be made invalid,
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2266 containing the bitwise OR of one or
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]2267 more of
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2268 PNG_INFO_gAMA, PNG_INFO_sBIT,
2269 PNG_INFO_cHRM, PNG_INFO_PLTE,
2270 PNG_INFO_tRNS, PNG_INFO_bKGD,
2271 PNG_INFO_hIST, PNG_INFO_pHYs,
2272 PNG_INFO_oFFs, PNG_INFO_tIME,
2273 PNG_INFO_pCAL, PNG_INFO_sRGB,
2274 PNG_INFO_iCCP, PNG_INFO_sPLT,
2275 PNG_INFO_sCAL, PNG_INFO_IDAT
2276
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2277For a more compact example of reading a PNG image, see the file example.c.
2278
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2279.SS Reading PNG files progressively
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2280
2281The progressive reader is slightly different then the non-progressive
2282reader. Instead of calling png_read_info(), png_read_rows(), and
2283png_read_end(), you make one call to png_process_data(), which calls
2284callbacks when it has the info, a row, or the end of the image. You
2285set up these callbacks with png_set_progressive_read_fn(). You don't
2286have to worry about the input/output functions of libpng, as you are
2287giving the library the data directly in png_process_data(). I will
2288assume that you have read the section on reading PNG files above,
2289so I will only highlight the differences (although I will show
2290all of the code).
2291
2292png_structp png_ptr;
2293png_infop info_ptr;
2294
2295 /* An example code fragment of how you would
2296 initialize the progressive reader in your
2297 application. */
2298 int
2299 initialize_png_reader()
2300 {
2301 png_ptr = png_create_read_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2302 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2303 user_error_fn, user_warning_fn);
2304 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2305 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2306 info_ptr = png_create_info_struct(png_ptr);
2307 if (!info_ptr)
2308 {
2309 png_destroy_read_struct(&png_ptr, (png_infopp)NULL,
2310 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2311 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2312 }
2313
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2314 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2315 {
2316 png_destroy_read_struct(&png_ptr, &info_ptr,
2317 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2318 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2319 }
2320
2321 /* This one's new. You can provide functions
2322 to be called when the header info is valid,
2323 when each row is completed, and when the image
2324 is finished. If you aren't using all functions,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2325 you can specify NULL parameters. Even when all
2326 three functions are NULL, you need to call
2327 png_set_progressive_read_fn(). You can use
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2328 any struct as the user_ptr (cast to a void pointer
2329 for the function call), and retrieve the pointer
2330 from inside the callbacks using the function
2331
2332 png_get_progressive_ptr(png_ptr);
2333
2334 which will return a void pointer, which you have
2335 to cast appropriately.
2336 */
2337 png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
2338 info_callback, row_callback, end_callback);
2339
2340 return 0;
2341 }
2342
2343 /* A code fragment that you call as you receive blocks
2344 of data */
2345 int
2346 process_data(png_bytep buffer, png_uint_32 length)
2347 {
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2348 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2349 {
2350 png_destroy_read_struct(&png_ptr, &info_ptr,
2351 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2352 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2353 }
2354
2355 /* This one's new also. Simply give it a chunk
2356 of data from the file stream (in order, of
2357 course). On machines with segmented memory
2358 models machines, don't give it any more than
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2359 64K. The library seems to run fine with sizes
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2360 of 4K. Although you can give it much less if
2361 necessary (I assume you can give it chunks of
2362 1 byte, I haven't tried less then 256 bytes
2363 yet). When this function returns, you may
2364 want to display any rows that were generated
2365 in the row callback if you don't already do
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2366 so there.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2367 */
2368 png_process_data(png_ptr, info_ptr, buffer, length);
2369 return 0;
2370 }
2371
2372 /* This function is called (as set by
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2373 png_set_progressive_read_fn() above) when enough data
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2374 has been supplied so all of the header has been
2375 read.
2376 */
2377 void
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2378 info_callback(png_structp png_ptr, png_infop info)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2379 {
2380 /* Do any setup here, including setting any of
2381 the transformations mentioned in the Reading
2382 PNG files section. For now, you _must_ call
2383 either png_start_read_image() or
2384 png_read_update_info() after all the
2385 transformations are set (even if you don't set
2386 any). You may start getting rows before
2387 png_process_data() returns, so this is your
2388 last chance to prepare for that.
2389 */
2390 }
2391
2392 /* This function is called when each row of image
2393 data is complete */
2394 void
2395 row_callback(png_structp png_ptr, png_bytep new_row,
Glenn Randers-Pehrsone68f5a32001-05-14 09:20:53 -0500[diff] [blame]2396 png_uint_32 row_num, int pass)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2397 {
2398 /* If the image is interlaced, and you turned
2399 on the interlace handler, this function will
2400 be called for every row in every pass. Some
2401 of these rows will not be changed from the
2402 previous pass. When the row is not changed,
2403 the new_row variable will be NULL. The rows
2404 and passes are called in order, so you don't
2405 really need the row_num and pass, but I'm
2406 supplying them because it may make your life
2407 easier.
2408
2409 For the non-NULL rows of interlaced images,
2410 you must call png_progressive_combine_row()
2411 passing in the row and the old row. You can
2412 call this function for NULL rows (it will just
2413 return) and for non-interlaced images (it just
2414 does the memcpy for you) if it will make the
2415 code easier. Thus, you can just do this for
2416 all cases:
2417 */
2418
2419 png_progressive_combine_row(png_ptr, old_row,
2420 new_row);
2421
2422 /* where old_row is what was displayed for
Glenn Randers-Pehrson345bc271998-06-14 14:43:31 -0500[diff] [blame]2423 previously for the row. Note that the first
2424 pass (pass == 0, really) will completely cover
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2425 the old row, so the rows do not have to be
2426 initialized. After the first pass (and only
2427 for interlaced images), you will have to pass
2428 the current row, and the function will combine
2429 the old row and the new row.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2430 */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2431 }
2432
2433 void
2434 end_callback(png_structp png_ptr, png_infop info)
2435 {
2436 /* This function is called after the whole image
2437 has been read, including any chunks after the
2438 image (up to and including the IEND). You
2439 will usually have the same info chunk as you
2440 had in the header, although some data may have
2441 been added to the comments and time fields.
2442
2443 Most people won't do much here, perhaps setting
2444 a flag that marks the image as finished.
2445 */
2446 }
2447
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]2448
2449
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2450.SH IV. Writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2451
2452Much of this is very similar to reading. However, everything of
2453importance is repeated here, so you won't have to constantly look
2454back up in the reading section to understand writing.
2455
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2456.SS Setup
2457
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2458You will want to do the I/O initialization before you get into libpng,
2459so if it doesn't work, you don't have anything to undo. If you are not
2460using the standard I/O functions, you will need to replace them with
2461custom writing functions. See the discussion under Customizing libpng.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2462
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2463 FILE *fp = fopen(file_name, "wb");
2464 if (!fp)
2465 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2466 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2467 }
2468
2469Next, png_struct and png_info need to be allocated and initialized.
2470As these can be both relatively large, you may not want to store these
2471on the stack, unless you have stack space to spare. Of course, you
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2472will want to check if they return NULL. If you are also reading,
2473you won't want to name your read structure and your write structure
2474both "png_ptr"; you can call them anything you like, such as
2475"read_ptr" and "write_ptr". Look at pngtest.c, for example.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2476
2477 png_structp png_ptr = png_create_write_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2478 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2479 user_error_fn, user_warning_fn);
2480 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2481 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2482
2483 png_infop info_ptr = png_create_info_struct(png_ptr);
2484 if (!info_ptr)
2485 {
2486 png_destroy_write_struct(&png_ptr,
2487 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2488 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2489 }
2490
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]2491If you want to use your own memory allocation routines,
2492define PNG_USER_MEM_SUPPORTED and use
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2493png_create_write_struct_2() instead of png_create_write_struct():
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]2494
2495 png_structp png_ptr = png_create_write_struct_2
2496 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
2497 user_error_fn, user_warning_fn, (png_voidp)
2498 user_mem_ptr, user_malloc_fn, user_free_fn);
2499
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2500After you have these structures, you will need to set up the
2501error handling. When libpng encounters an error, it expects to
2502longjmp() back to your routine. Therefore, you will need to call
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2503setjmp() and pass the png_jmpbuf(png_ptr). If you
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2504write the file from different routines, you will need to update
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2505the png_jmpbuf(png_ptr) every time you enter a new routine that will
2506call a png_*() function. See your documentation of setjmp/longjmp
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2507for your compiler for more information on setjmp/longjmp. See
2508the discussion on libpng error handling in the Customizing Libpng
2509section below for more information on the libpng error handling.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2510
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2511 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2512 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2513 png_destroy_write_struct(&png_ptr, &info_ptr);
2514 fclose(fp);
2515 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2516 }
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2517 ...
2518 return;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2519
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2520If you would rather avoid the complexity of setjmp/longjmp issues,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]2521you can compile libpng with PNG_NO_SETJMP, in which case
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2522errors will result in a call to PNG_ABORT() which defaults to abort().
2523
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]2524You can #define PNG_ABORT() to a function that does something
2525more useful than abort(), as long as your function does not
2526return.
2527
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2528Now you need to set up the output code. The default for libpng is to
2529use the C function fwrite(). If you use this, you will need to pass a
2530valid FILE * in the function png_init_io(). Be sure that the file is
2531opened in binary mode. Again, if you wish to handle writing data in
2532another way, see the discussion on libpng I/O handling in the Customizing
2533Libpng section below.
2534
2535 png_init_io(png_ptr, fp);
2536
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]2537If you are embedding your PNG into a datastream such as MNG, and don't
2538want libpng to write the 8-byte signature, or if you have already
2539written the signature in your application, use
2540
2541 png_set_sig_bytes(png_ptr, 8);
2542
2543to inform libpng that it should not write a signature.
2544
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2545.SS Write callbacks
2546
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2547At this point, you can set up a callback function that will be
2548called after each row has been written, which you can use to control
2549a progress meter or the like. It's demonstrated in pngtest.c.
2550You must supply a function
2551
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2552 void write_row_callback(png_ptr, png_uint_32 row,
2553 int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2554 {
2555 /* put your code here */
2556 }
2557
2558(You can give it another name that you like instead of "write_row_callback")
2559
2560To inform libpng about your function, use
2561
2562 png_set_write_status_fn(png_ptr, write_row_callback);
2563
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2564You now have the option of modifying how the compression library will
2565run. The following functions are mainly for testing, but may be useful
2566in some cases, like if you need to write PNG files extremely fast and
2567are willing to give up some compression, or if you want to get the
2568maximum possible compression at the expense of slower writing. If you
2569have no special needs in this area, let the library do what it wants by
2570not calling this function at all, as it has been tuned to deliver a good
2571speed/compression ratio. The second parameter to png_set_filter() is
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2572the filter method, for which the only valid values are 0 (as of the
2573July 1999 PNG specification, version 1.2) or 64 (if you are writing
2574a PNG datastream that is to be embedded in a MNG datastream). The third
2575parameter is a flag that indicates which filter type(s) are to be tested
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2576for each scanline. See the PNG specification for details on the specific
2577filter types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2578
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2579
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2580 /* turn on or off filtering, and/or choose
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2581 specific filters. You can use either a single
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2582 PNG_FILTER_VALUE_NAME or the bitwise OR of one
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2583 or more PNG_FILTER_NAME masks. */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2584 png_set_filter(png_ptr, 0,
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2585 PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
2586 PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
2587 PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]2588 PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2589 PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
2590 PNG_ALL_FILTERS);
2591
2592If an application
2593wants to start and stop using particular filters during compression,
2594it should start out with all of the filters (to ensure that the previous
2595row of pixels will be stored in case it's needed later), and then add
2596and remove them after the start of compression.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2597
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2598If you are writing a PNG datastream that is to be embedded in a MNG
2599datastream, the second parameter can be either 0 or 64.
2600
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]2601The png_set_compression_*() functions interface to the zlib compression
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2602library, and should mostly be ignored unless you really know what you are
2603doing. The only generally useful call is png_set_compression_level()
2604which changes how much time zlib spends on trying to compress the image
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2605data. See the Compression Library (zlib.h and algorithm.txt, distributed
2606with zlib) for details on the compression levels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2607
2608 /* set the zlib compression level */
2609 png_set_compression_level(png_ptr,
2610 Z_BEST_COMPRESSION);
2611
2612 /* set other zlib parameters */
2613 png_set_compression_mem_level(png_ptr, 8);
2614 png_set_compression_strategy(png_ptr,
2615 Z_DEFAULT_STRATEGY);
2616 png_set_compression_window_bits(png_ptr, 15);
2617 png_set_compression_method(png_ptr, 8);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2618 png_set_compression_buffer_size(png_ptr, 8192)
2619
2620extern PNG_EXPORT(void,png_set_zbuf_size)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2621
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2622.SS Setting the contents of info for output
2623
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2624You now need to fill in the png_info structure with all the data you
2625wish to write before the actual image. Note that the only thing you
2626are allowed to write after the image is the text chunks and the time
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2627chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2628the latest PNG specification for more information on that. If you
2629wish to write them before the image, fill them in now, and flag that
2630data as being valid. If you want to wait until after the data, don't
2631fill them until png_write_end(). For all the fields in png_info and
2632their data types, see png.h. For explanations of what the fields
2633contain, see the PNG specification.
2634
2635Some of the more important parts of the png_info are:
2636
2637 png_set_IHDR(png_ptr, info_ptr, width, height,
2638 bit_depth, color_type, interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2639 compression_type, filter_method)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2640 width - holds the width of the image
2641 in pixels (up to 2^31).
2642 height - holds the height of the image
2643 in pixels (up to 2^31).
2644 bit_depth - holds the bit depth of one of the
2645 image channels.
2646 (valid values are 1, 2, 4, 8, 16
2647 and depend also on the
2648 color_type. See also significant
2649 bits (sBIT) below).
2650 color_type - describes which color/alpha
2651 channels are present.
2652 PNG_COLOR_TYPE_GRAY
2653 (bit depths 1, 2, 4, 8, 16)
2654 PNG_COLOR_TYPE_GRAY_ALPHA
2655 (bit depths 8, 16)
2656 PNG_COLOR_TYPE_PALETTE
2657 (bit depths 1, 2, 4, 8)
2658 PNG_COLOR_TYPE_RGB
2659 (bit_depths 8, 16)
2660 PNG_COLOR_TYPE_RGB_ALPHA
2661 (bit_depths 8, 16)
2662
2663 PNG_COLOR_MASK_PALETTE
2664 PNG_COLOR_MASK_COLOR
2665 PNG_COLOR_MASK_ALPHA
2666
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2667 interlace_type - PNG_INTERLACE_NONE or
2668 PNG_INTERLACE_ADAM7
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2669 compression_type - (must be
2670 PNG_COMPRESSION_TYPE_DEFAULT)
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2671 filter_method - (must be PNG_FILTER_TYPE_DEFAULT
2672 or, if you are writing a PNG to
2673 be embedded in a MNG datastream,
2674 can also be
2675 PNG_INTRAPIXEL_DIFFERENCING)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2676
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2677If you call png_set_IHDR(), the call must appear before any of the
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]2678other png_set_*() functions, because they might require access to some of
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2679the IHDR settings. The remaining png_set_*() functions can be called
2680in any order.
2681
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]2682If you wish, you can reset the compression_type, interlace_type, or
2683filter_method later by calling png_set_IHDR() again; if you do this, the
2684width, height, bit_depth, and color_type must be the same in each call.
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]2685
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2686 png_set_PLTE(png_ptr, info_ptr, palette,
2687 num_palette);
2688 palette - the palette for the file
2689 (array of png_color)
2690 num_palette - number of entries in the palette
2691
2692 png_set_gAMA(png_ptr, info_ptr, gamma);
2693 gamma - the gamma the image was created
2694 at (PNG_INFO_gAMA)
2695
2696 png_set_sRGB(png_ptr, info_ptr, srgb_intent);
2697 srgb_intent - the rendering intent
2698 (PNG_INFO_sRGB) The presence of
2699 the sRGB chunk means that the pixel
2700 data is in the sRGB color space.
2701 This chunk also implies specific
2702 values of gAMA and cHRM. Rendering
2703 intent is the CSS-1 property that
2704 has been defined by the International
2705 Color Consortium
2706 (http://www.color.org).
2707 It can be one of
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]2708 PNG_sRGB_INTENT_SATURATION,
2709 PNG_sRGB_INTENT_PERCEPTUAL,
2710 PNG_sRGB_INTENT_ABSOLUTE, or
2711 PNG_sRGB_INTENT_RELATIVE.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2712
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2713
2714 png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
2715 srgb_intent);
2716 srgb_intent - the rendering intent
2717 (PNG_INFO_sRGB) The presence of the
2718 sRGB chunk means that the pixel
2719 data is in the sRGB color space.
2720 This function also causes gAMA and
2721 cHRM chunks with the specific values
2722 that are consistent with sRGB to be
2723 written.
2724
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2725 png_set_iCCP(png_ptr, info_ptr, name, compression_type,
2726 profile, proflen);
2727 name - The profile name.
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2728 compression - The compression type; always
2729 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
2730 You may give NULL to this argument to
2731 ignore it.
2732 profile - International Color Consortium color
2733 profile data. May contain NULs.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2734 proflen - length of profile data in bytes.
2735
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2736 png_set_sBIT(png_ptr, info_ptr, sig_bit);
2737 sig_bit - the number of significant bits for
2738 (PNG_INFO_sBIT) each of the gray, red,
2739 green, and blue channels, whichever are
2740 appropriate for the given color type
2741 (png_color_16)
2742
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]2743 png_set_tRNS(png_ptr, info_ptr, trans_alpha,
2744 num_trans, trans_color);
Glenn Randers-Pehrson866b62a2009-08-08 16:33:14 -0500[diff] [blame]2745 trans_alpha - array of alpha (transparency)
2746 entries for palette (PNG_INFO_tRNS)
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]2747 trans_color - graylevel or color sample values
2748 (in order red, green, blue) of the
2749 single transparent color for
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]2750 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2751 num_trans - number of transparent entries
2752 (PNG_INFO_tRNS)
2753
2754 png_set_hIST(png_ptr, info_ptr, hist);
2755 (PNG_INFO_hIST)
2756 hist - histogram of palette (array of
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2757 png_uint_16)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2758
2759 png_set_tIME(png_ptr, info_ptr, mod_time);
2760 mod_time - time image was last modified
2761 (PNG_VALID_tIME)
2762
2763 png_set_bKGD(png_ptr, info_ptr, background);
2764 background - background color (PNG_VALID_bKGD)
2765
2766 png_set_text(png_ptr, info_ptr, text_ptr, num_text);
2767 text_ptr - array of png_text holding image
2768 comments
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2769 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2770 on "text" PNG_TEXT_COMPRESSION_NONE
2771 PNG_TEXT_COMPRESSION_zTXt
2772 PNG_ITXT_COMPRESSION_NONE
2773 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2774 text_ptr[i].key - keyword for comment. Must contain
2775 1-79 characters.
2776 text_ptr[i].text - text comments for current
2777 keyword. Can be NULL or empty.
2778 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2779 after decompression, 0 for iTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2780 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2781 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2782 text_ptr[i].lang - language of comment (NULL or
2783 empty for unknown).
2784 text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
2785 or empty for unknown).
Glenn Randers-Pehrson8f5846f2009-10-31 21:31:08 -0500[diff] [blame]2786 Note that the itxt_length, lang, and lang_key
2787 members of the text_ptr structure only exist
2788 when the library is built with iTXt chunk support.
2789
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2790 num_text - number of comments
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2791
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2792 png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
2793 num_spalettes);
2794 palette_ptr - array of png_sPLT_struct structures
2795 to be added to the list of palettes
2796 in the info structure.
2797 num_spalettes - number of palette structures to be
2798 added.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2799
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2800 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
2801 unit_type);
2802 offset_x - positive offset from the left
2803 edge of the screen
2804 offset_y - positive offset from the top
2805 edge of the screen
2806 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
2807
2808 png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
2809 unit_type);
2810 res_x - pixels/unit physical resolution
2811 in x direction
2812 res_y - pixels/unit physical resolution
2813 in y direction
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2814 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2815 PNG_RESOLUTION_METER
2816
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2817 png_set_sCAL(png_ptr, info_ptr, unit, width, height)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2818 unit - physical scale units (an integer)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2819 width - width of a pixel in physical scale units
2820 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2821 (width and height are doubles)
2822
2823 png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
2824 unit - physical scale units (an integer)
2825 width - width of a pixel in physical scale units
2826 height - height of a pixel in physical scale units
2827 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2828
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2829 png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
2830 num_unknowns)
2831 unknowns - array of png_unknown_chunk
2832 structures holding unknown chunks
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2833 unknowns[i].name - name of unknown chunk
2834 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2835 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2836 unknowns[i].location - position to write chunk in file
2837 0: do not write chunk
2838 PNG_HAVE_IHDR: before PLTE
2839 PNG_HAVE_PLTE: before IDAT
2840 PNG_AFTER_IDAT: after IDAT
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2841
2842The "location" member is set automatically according to
2843what part of the output file has already been written.
2844You can change its value after calling png_set_unknown_chunks()
2845as demonstrated in pngtest.c. Within each of the "locations",
2846the chunks are sequenced according to their position in the
2847structure (that is, the value of "i", which is the order in which
2848the chunk was either read from the input file or defined with
2849png_set_unknown_chunks).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2850
2851A quick word about text and num_text. text is an array of png_text
2852structures. num_text is the number of valid structures in the array.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2853Each png_text structure holds a language code, a keyword, a text value,
2854and a compression type.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2855
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2856The compression types have the same valid numbers as the compression
2857types of the image data. Currently, the only valid number is zero.
2858However, you can store text either compressed or uncompressed, unlike
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2859images, which always have to be compressed. So if you don't want the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2860text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2861Because tEXt and zTXt chunks don't have a language field, if you
2862specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
2863any language code or translated keyword will not be written out.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2864
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2865Until text gets around 1000 bytes, it is not worth compressing it.
2866After the text has been written out to the file, the compression type
2867is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
2868so that it isn't written out again at the end (in case you are calling
2869png_write_end() with the same struct.
2870
2871The keywords that are given in the PNG Specification are:
2872
2873 Title Short (one line) title or
2874 caption for image
2875 Author Name of image's creator
2876 Description Description of image (possibly long)
2877 Copyright Copyright notice
2878 Creation Time Time of original image creation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2879 (usually RFC 1123 format, see below)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2880 Software Software used to create the image
2881 Disclaimer Legal disclaimer
2882 Warning Warning of nature of content
2883 Source Device used to create the image
2884 Comment Miscellaneous comment; conversion
2885 from other image format
2886
2887The keyword-text pairs work like this. Keywords should be short
2888simple descriptions of what the comment is about. Some typical
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2889keywords are found in the PNG specification, as is some recommendations
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2890on keywords. You can repeat keywords in a file. You can even write
2891some text before the image and some after. For example, you may want
2892to put a description of the image before the image, but leave the
2893disclaimer until after, so viewers working over modem connections
2894don't have to wait for the disclaimer to go over the modem before
2895they start seeing the image. Finally, keywords should be full
2896words, not abbreviations. Keywords and text are in the ISO 8859-1
2897(Latin-1) character set (a superset of regular ASCII) and can not
2898contain NUL characters, and should not contain control or other
2899unprintable characters. To make the comments widely readable, stick
2900with basic ASCII, and avoid machine specific character set extensions
2901like the IBM-PC character set. The keyword must be present, but
2902you can leave off the text string on non-compressed pairs.
2903Compressed pairs must have a text string, as only the text string
2904is compressed anyway, so the compression would be meaningless.
2905
2906PNG supports modification time via the png_time structure. Two
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2907conversion routines are provided, png_convert_from_time_t() for
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2908time_t and png_convert_from_struct_tm() for struct tm. The
2909time_t routine uses gmtime(). You don't have to use either of
2910these, but if you wish to fill in the png_time structure directly,
2911you should provide the time in universal time (GMT) if possible
2912instead of your local time. Note that the year number is the full
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2913year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2914that months start with 1.
2915
2916If you want to store the time of the original image creation, you should
2917use a plain tEXt chunk with the "Creation Time" keyword. This is
2918necessary because the "creation time" of a PNG image is somewhat vague,
2919depending on whether you mean the PNG file, the time the image was
2920created in a non-PNG format, a still photo from which the image was
2921scanned, or possibly the subject matter itself. In order to facilitate
2922machine-readable dates, it is recommended that the "Creation Time"
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2923tEXt 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]2924although this isn't a requirement. Unlike the tIME chunk, the
2925"Creation Time" tEXt chunk is not expected to be automatically changed
2926by the software. To facilitate the use of RFC 1123 dates, a function
2927png_convert_to_rfc1123(png_timep) is provided to convert from PNG
2928time to an RFC 1123 format string.
2929
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2930.SS Writing unknown chunks
2931
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2932You can use the png_set_unknown_chunks function to queue up chunks
2933for writing. You give it a chunk name, raw data, and a size; that's
2934all there is to it. The chunks will be written by the next following
2935png_write_info_before_PLTE, png_write_info, or png_write_end function.
2936Any chunks previously read into the info structure's unknown-chunk
2937list will also be written out in a sequence that satisfies the PNG
2938specification's ordering rules.
2939
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2940.SS The high-level write interface
2941
2942At this point there are two ways to proceed; through the high-level
2943write interface, or through a sequence of low-level write operations.
2944You can use the high-level interface if your image data is present
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2945in the info structure. All defined output
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]2946transformations are permitted, enabled by the following masks.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2947
2948 PNG_TRANSFORM_IDENTITY No transformation
2949 PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2950 PNG_TRANSFORM_PACKSWAP Change order of packed
2951 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2952 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2953 PNG_TRANSFORM_SHIFT Normalize pixels to the
2954 sBIT depth
2955 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
2956 to BGRA
2957 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
2958 to AG
2959 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
2960 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2961 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson1eb14e92008-12-10 07:14:45 -0600[diff] [blame]2962 PNG_TRANSFORM_STRIP_FILLER Strip out filler
2963 bytes (deprecated).
2964 PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
2965 filler bytes
2966 PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
2967 filler bytes
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2968
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2969If you have valid image data in the info structure (you can use
2970png_set_rows() to put image data in the info structure), simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2971
2972 png_write_png(png_ptr, info_ptr, png_transforms, NULL)
2973
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2974where png_transforms is an integer containing the bitwise OR of some set of
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2975transformation flags. This call is equivalent to png_write_info(),
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2976followed the set of transformations indicated by the transform mask,
2977then png_write_image(), and finally png_write_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2978
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2979(The final parameter of this call is not yet used. Someday it might point
2980to transformation parameters required by some future output transform.)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2981
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]2982You must use png_transforms and not call any png_set_transform() functions
2983when you use png_write_png().
2984
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2985.SS The low-level write interface
2986
2987If you are going the low-level route instead, you are now ready to
2988write all the file information up to the actual image data. You do
2989this with a call to png_write_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2990
2991 png_write_info(png_ptr, info_ptr);
2992
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2993Note that there is one transformation you may need to do before
2994png_write_info(). In PNG files, the alpha channel in an image is the
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]2995level of opacity. If your data is supplied as a level of transparency,
2996you can invert the alpha channel before you write it, so that 0 is
2997fully transparent and 255 (in 8-bit or paletted images) or 65535
2998(in 16-bit images) is fully opaque, with
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2999
3000 png_set_invert_alpha(png_ptr);
3001
3002This must appear before png_write_info() instead of later with the
3003other transformations because in the case of paletted images the tRNS
3004chunk data has to be inverted before the tRNS chunk is written. If
3005your image is not a paletted image, the tRNS data (which in such cases
3006represents a single color to be rendered as transparent) won't need to
3007be changed, and you can safely do this transformation after your
3008png_write_info() call.
3009
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3010If you need to write a private chunk that you want to appear before
3011the PLTE chunk when PLTE is present, you can write the PNG info in
3012two steps, and insert code to write your own chunk between them:
3013
3014 png_write_info_before_PLTE(png_ptr, info_ptr);
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3015 png_set_unknown_chunks(png_ptr, info_ptr, ...);
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]3016 png_write_info(png_ptr, info_ptr);
3017
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3018After you've written the file information, you can set up the library
3019to handle any special transformations of the image data. The various
3020ways to transform the data will be described in the order that they
3021should occur. This is important, as some of these change the color
3022type and/or bit depth of the data, and some others only work on
3023certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3024checks 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]3025make sure to only enable a transformation if it will be valid for the
3026data. For example, don't swap red and blue on grayscale data.
3027
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3028PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]3029the 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]3030to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
3031bytes per pixel).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3032
3033 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
3034
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3035where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3036PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
3037is stored XRGB or RGBX.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3038
3039PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
3040they can, resulting in, for example, 8 pixels per byte for 1 bit files.
3041If the data is supplied at 1 pixel per byte, use this code, which will
3042correctly pack the pixels into a single byte:
3043
3044 png_set_packing(png_ptr);
3045
3046PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
3047data is of another bit depth, you can write an sBIT chunk into the
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3048file so that decoders can recover the original data if desired.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3049
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3050 /* Set the true bit depth of the image data */
3051 if (color_type & PNG_COLOR_MASK_COLOR)
3052 {
3053 sig_bit.red = true_bit_depth;
3054 sig_bit.green = true_bit_depth;
3055 sig_bit.blue = true_bit_depth;
3056 }
3057 else
3058 {
3059 sig_bit.gray = true_bit_depth;
3060 }
3061 if (color_type & PNG_COLOR_MASK_ALPHA)
3062 {
3063 sig_bit.alpha = true_bit_depth;
3064 }
3065
3066 png_set_sBIT(png_ptr, info_ptr, &sig_bit);
3067
3068If 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]3069one 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]3070this will scale the values to appear to be the correct bit depth as
3071is required by PNG.
3072
3073 png_set_shift(png_ptr, &sig_bit);
3074
3075PNG files store 16 bit pixels in network byte order (big-endian,
3076ie. most significant bits first). This code would be used if they are
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3077supplied the other way (little-endian, i.e. least significant bits
3078first, the way PCs store them):
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3079
3080 if (bit_depth > 8)
3081 png_set_swap(png_ptr);
3082
3083If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
3084need to change the order the pixels are packed into bytes, you can use:
3085
3086 if (bit_depth < 8)
3087 png_set_packswap(png_ptr);
3088
3089PNG files store 3 color pixels in red, green, blue order. This code
3090would be used if they are supplied as blue, green, red:
3091
3092 png_set_bgr(png_ptr);
3093
3094PNG files describe monochrome as black being zero and white being
3095one. This code would be used if the pixels are supplied with this reversed
3096(black being one and white being zero):
3097
3098 png_set_invert_mono(png_ptr);
3099
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3100Finally, you can write your own transformation function if none of
3101the existing ones meets your needs. This is done by setting a callback
3102with
3103
3104 png_set_write_user_transform_fn(png_ptr,
3105 write_transform_fn);
3106
3107You must supply the function
3108
3109 void write_transform_fn(png_ptr ptr, row_info_ptr
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3110 row_info, png_bytep data)
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3111
3112See pngtest.c for a working example. Your function will be called
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3113before any of the other transformations are processed.
3114
3115You can also set up a pointer to a user structure for use by your
3116callback function.
3117
3118 png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
3119
3120The user_channels and user_depth parameters of this function are ignored
3121when writing; you can set them to zero as shown.
3122
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3123You can retrieve the pointer via the function png_get_user_transform_ptr().
3124For example:
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3125
3126 voidp write_user_transform_ptr =
3127 png_get_user_transform_ptr(png_ptr);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3128
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3129It is possible to have libpng flush any pending output, either manually,
3130or automatically after a certain number of lines have been written. To
3131flush the output stream a single time call:
3132
3133 png_write_flush(png_ptr);
3134
3135and to have libpng flush the output stream periodically after a certain
3136number of scanlines have been written, call:
3137
3138 png_set_flush(png_ptr, nrows);
3139
3140Note that the distance between rows is from the last time png_write_flush()
3141was called, or the first row of the image if it has never been called.
3142So if you write 50 lines, and then png_set_flush 25, it will flush the
3143output on the next scanline, and every 25 lines thereafter, unless
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3144png_write_flush() is called before 25 more lines have been written.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3145If 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]3146RGB image) the image compression may decrease noticeably (although this
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3147may be acceptable for real-time applications). Infrequent flushing will
3148only degrade the compression performance by a few percent over images
3149that do not use flushing.
3150
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3151.SS Writing the image data
3152
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3153That's it for the transformations. Now you can write the image data.
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3154The 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]3155whole image in memory, you can just call png_write_image() and libpng
3156will write the image. You will need to pass in an array of pointers to
3157each row. This function automatically handles interlacing, so you don't
3158need to call png_set_interlace_handling() or call this function multiple
3159times, or any of that other stuff necessary with png_write_rows().
3160
3161 png_write_image(png_ptr, row_pointers);
3162
3163where row_pointers is:
3164
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3165 png_byte *row_pointers[height];
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3166
3167You can point to void or char or whatever you use for pixels.
3168
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3169If you don't want to write the whole image at once, you can
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3170use png_write_rows() instead. If the file is not interlaced,
3171this is simple:
3172
3173 png_write_rows(png_ptr, row_pointers,
3174 number_of_rows);
3175
3176row_pointers is the same as in the png_write_image() call.
3177
3178If 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]3179a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3180
3181 png_bytep row_pointer = row;
3182
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3183 png_write_row(png_ptr, row_pointer);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3184
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3185When the file is interlaced, things can get a good deal more complicated.
3186The only currently (as of the PNG Specification version 1.2, dated July
31871999) defined interlacing scheme for PNG files is the "Adam7" interlace
3188scheme, that breaks down an image into seven smaller images of varying
3189size. libpng will build these images for you, or you can do them
3190yourself. If you want to build them yourself, see the PNG specification
3191for details of which pixels to write when.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3192
3193If you don't want libpng to handle the interlacing details, just
3194use png_set_interlace_handling() and call png_write_rows() the
3195correct number of times to write all seven sub-images.
3196
3197If you want libpng to build the sub-images, call this before you start
3198writing any rows:
3199
3200 number_of_passes =
3201 png_set_interlace_handling(png_ptr);
3202
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3203This will return the number of passes needed. Currently, this is seven,
3204but may change if another interlace type is added.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3205
3206Then write the complete image number_of_passes times.
3207
3208 png_write_rows(png_ptr, row_pointers,
3209 number_of_rows);
3210
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3211As some of these rows are not used, and thus return immediately, you may
3212want to read about interlacing in the PNG specification, and only update
3213the rows that are actually used.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3214
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3215.SS Finishing a sequential write
3216
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3217After you are finished writing the image, you should finish writing
3218the file. If you are interested in writing comments or time, you should
3219pass an appropriately filled png_info pointer. If you are not interested,
3220you can pass NULL.
3221
3222 png_write_end(png_ptr, info_ptr);
3223
3224When you are done, you can free all memory used by libpng like this:
3225
3226 png_destroy_write_struct(&png_ptr, &info_ptr);
3227
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3228It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3229point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3230
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3231 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3232 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3233 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3234 more of
3235 PNG_FREE_PLTE, PNG_FREE_TRNS,
3236 PNG_FREE_HIST, PNG_FREE_ICCP,
3237 PNG_FREE_PCAL, PNG_FREE_ROWS,
3238 PNG_FREE_SCAL, PNG_FREE_SPLT,
3239 PNG_FREE_TEXT, PNG_FREE_UNKN,
3240 or simply PNG_FREE_ALL
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3241 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3242 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3243
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3244This function may be safely called when the relevant storage has
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3245already been freed, or has not yet been allocated, or was allocated
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3246by the user and not by libpng, and will in those cases do nothing.
3247The "seq" parameter is ignored if only one item of the selected data
3248type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
3249are allowed for the data type identified in the mask, such as text or
3250sPLT, 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]3251
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3252If you allocated data such as a palette that you passed in to libpng
3253with png_set_*, you must not free it until just before the call to
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3254png_destroy_write_struct().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3255
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3256The default behavior is only to free data that was allocated internally
3257by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3258or so that it will free data that was allocated by the user with png_malloc()
3259or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3260
3261 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3262 mask - which data elements are affected
3263 same choices as in png_free_data()
3264 freer - one of
3265 PNG_DESTROY_WILL_FREE_DATA
3266 PNG_SET_WILL_FREE_DATA
3267 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3268
3269For example, to transfer responsibility for some data from a read structure
3270to a write structure, you could use
3271
3272 png_data_freer(read_ptr, read_info_ptr,
3273 PNG_USER_WILL_FREE_DATA,
3274 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
3275 png_data_freer(write_ptr, write_info_ptr,
3276 PNG_DESTROY_WILL_FREE_DATA,
3277 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
3278
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3279thereby briefly reassigning responsibility for freeing to the user but
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3280immediately afterwards reassigning it once more to the write_destroy
3281function. Having done this, it would then be safe to destroy the read
3282structure and continue to use the PLTE, tRNS, and hIST data in the write
3283structure.
3284
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3285This function only affects data that has already been allocated.
3286You can call this function before calling after the png_set_*() functions
3287to control whether the user or png_destroy_*() is supposed to free the data.
3288When the user assumes responsibility for libpng-allocated data, the
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3289application must use
3290png_free() to free it, and when the user transfers responsibility to libpng
3291for data that the user has allocated, the user must have used png_malloc()
3292or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3293
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3294If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
3295separately, do not transfer responsibility for freeing text_ptr to libpng,
3296because when libpng fills a png_text structure it combines these members with
3297the key member, and png_free_data() will free only text_ptr.key. Similarly,
3298if you transfer responsibility for free'ing text_ptr from libpng to your
3299application, your application must not separately free those members.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3300For a more compact example of writing a PNG image, see the file example.c.
3301
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3302.SH V. Modifying/Customizing libpng:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3303
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3304There are two issues here. The first is changing how libpng does
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3305standard things like memory allocation, input/output, and error handling.
3306The second deals with more complicated things like adding new chunks,
3307adding new transformations, and generally changing how libpng works.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]3308Both of those are compile-time issues; that is, they are generally
3309determined at the time the code is written, and there is rarely a need
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3310to provide the user with a means of changing them.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]3311
3312Memory allocation, input/output, and error handling
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3313
3314All of the memory allocation, input/output, and error handling in libpng
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]3315goes through callbacks that are user-settable. The default routines are
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3316in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3317these functions, call the appropriate png_set_*_fn() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3318
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3319Memory allocation is done through the functions png_malloc(), png_calloc(),
3320and png_free(). These currently just call the standard C functions.
3321png_calloc() calls png_malloc() and then png_memset() to clear the newly
3322allocated memory to zero. If your pointers can't access more then 64K
3323at a time, you will want to set MAXSEG_64K in zlib.h. Since it is
3324unlikely that the method of handling memory allocation on a platform
3325will change between applications, these functions must be modified in
3326the library at compile time. If you prefer to use a different method
3327of allocating and freeing data, you can use png_create_read_struct_2() or
3328png_create_write_struct_2() to register your own functions as described
3329above. These functions also provide a void pointer that can be retrieved
3330via
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3331
3332 mem_ptr=png_get_mem_ptr(png_ptr);
3333
3334Your replacement memory functions must have prototypes as follows:
3335
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3336 png_voidp malloc_fn(png_structp png_ptr,
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]3337 png_alloc_size_t size);
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3338 void free_fn(png_structp png_ptr, png_voidp ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3339
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]3340Your malloc_fn() must return NULL in case of failure. The png_malloc()
3341function will normally call png_error() if it receives a NULL from the
3342system memory allocator or from your replacement malloc_fn().
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]3343
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3344Your free_fn() will never be called with a NULL ptr, since libpng's
3345png_free() checks for NULL before calling free_fn().
3346
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3347Input/Output in libpng is done through png_read() and png_write(),
3348which currently just call fread() and fwrite(). The FILE * is stored in
3349png_struct and is initialized via png_init_io(). If you wish to change
3350the method of I/O, the library supplies callbacks that you can set
3351through the function png_set_read_fn() and png_set_write_fn() at run
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3352time, instead of calling the png_init_io() function. These functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3353also provide a void pointer that can be retrieved via the function
3354png_get_io_ptr(). For example:
3355
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3356 png_set_read_fn(png_structp read_ptr,
3357 voidp read_io_ptr, png_rw_ptr read_data_fn)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3358
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3359 png_set_write_fn(png_structp write_ptr,
3360 voidp write_io_ptr, png_rw_ptr write_data_fn,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3361 png_flush_ptr output_flush_fn);
3362
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3363 voidp read_io_ptr = png_get_io_ptr(read_ptr);
3364 voidp write_io_ptr = png_get_io_ptr(write_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3365
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3366The replacement I/O functions must have prototypes as follows:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3367
3368 void user_read_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]3369 png_bytep data, png_size_t length);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3370 void user_write_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]3371 png_bytep data, png_size_t length);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3372 void user_flush_data(png_structp png_ptr);
3373
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3374The user_read_data() function is responsible for detecting and
3375handling end-of-data errors.
3376
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3377Supplying NULL for the read, write, or flush functions sets them back
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3378to using the default C stream functions, which expect the io_ptr to
3379point to a standard *FILE structure. It is probably a mistake
3380to use NULL for one of write_data_fn and output_flush_fn but not both
3381of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
3382It is an error to read from a write stream, and vice versa.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3383
3384Error handling in libpng is done through png_error() and png_warning().
3385Errors handled through png_error() are fatal, meaning that png_error()
3386should never return to its caller. Currently, this is handled via
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3387setjmp() and longjmp() (unless you have compiled libpng with
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]3388PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
Glenn Randers-Pehrson60988072010-04-13 22:11:06 -0500[diff] [blame]3389but you could change this to do things like exit() if you should wish,
Glenn Randers-Pehrson54ac9a92010-04-02 17:06:22 -0500[diff] [blame]3390as long as your function does not return.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3391
3392On non-fatal errors, png_warning() is called
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3393to print a warning message, and then control returns to the calling code.
3394By default png_error() and png_warning() print a message on stderr via
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3395fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
3396(because you don't want the messages) or PNG_NO_STDIO defined (because
3397fprintf() isn't available). If you wish to change the behavior of the error
3398functions, you will need to set up your own message callbacks. These
3399functions are normally supplied at the time that the png_struct is created.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3400It is also possible to redirect errors and warnings to your own replacement
3401functions after png_create_*_struct() has been called by calling:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3402
3403 png_set_error_fn(png_structp png_ptr,
3404 png_voidp error_ptr, png_error_ptr error_fn,
3405 png_error_ptr warning_fn);
3406
3407 png_voidp error_ptr = png_get_error_ptr(png_ptr);
3408
3409If NULL is supplied for either error_fn or warning_fn, then the libpng
3410default function will be used, calling fprintf() and/or longjmp() if a
3411problem is encountered. The replacement error functions should have
3412parameters as follows:
3413
3414 void user_error_fn(png_structp png_ptr,
3415 png_const_charp error_msg);
3416 void user_warning_fn(png_structp png_ptr,
3417 png_const_charp warning_msg);
3418
3419The motivation behind using setjmp() and longjmp() is the C++ throw and
3420catch exception handling methods. This makes the code much easier to write,
3421as there is no need to check every return code of every function call.
3422However, there are some uncertainties about the status of local variables
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3423after a longjmp, so the user may want to be careful about doing anything
3424after setjmp returns non-zero besides returning itself. Consult your
3425compiler documentation for more details. For an alternative approach, you
3426may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3427
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3428.SS Custom chunks
3429
3430If you need to read or write custom chunks, you may need to get deeper
3431into the libpng code. The library now has mechanisms for storing
3432and writing chunks of unknown type; you can even declare callbacks
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]3433for custom chunks. However, this may not be good enough if the
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3434library code itself needs to know about interactions between your
3435chunk and existing `intrinsic' chunks.
3436
3437If you need to write a new intrinsic chunk, first read the PNG
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3438specification. Acquire a first level of understanding of how it works.
3439Pay particular attention to the sections that describe chunk names,
3440and look at how other chunks were designed, so you can do things
3441similarly. Second, check out the sections of libpng that read and
3442write chunks. Try to find a chunk that is similar to yours and use
3443it as a template. More details can be found in the comments inside
3444the code. It is best to handle unknown chunks in a generic method,
3445via callback functions, instead of by modifying libpng functions.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3446
3447If you wish to write your own transformation for the data, look through
3448the part of the code that does the transformations, and check out some of
3449the simpler ones to get an idea of how they work. Try to find a similar
3450transformation to the one you want to add and copy off of it. More details
3451can be found in the comments inside the code itself.
3452
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3453.SS Configuring for 16 bit platforms
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3454
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3455You 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]3456it 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]3457won'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]3458
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3459.SS Configuring for DOS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3460
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3461For DOS users who only have access to the lower 640K, you will
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3462have to limit zlib's memory usage via a png_set_compression_mem_level()
3463call. See zlib.h or zconf.h in the zlib library for more information.
3464
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3465.SS Configuring for Medium Model
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3466
3467Libpng's support for medium model has been tested on most of the popular
3468compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
3469defined, and FAR gets defined to far in pngconf.h, and you should be
3470all set. Everything in the library (except for zlib's structure) is
3471expecting far data. You must use the typedefs with the p or pp on
3472the end for pointers (or at least look at them and be careful). Make
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3473note that the rows of data are defined as png_bytepp, which is an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3474unsigned char far * far *.
3475
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3476.SS Configuring for gui/windowing platforms:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3477
3478You will need to write new error and warning functions that use the GUI
3479interface, as described previously, and set them to be the error and
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3480warning functions at the time that png_create_*_struct() is called,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3481in order to have them available during the structure initialization.
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3482They can be changed later via png_set_error_fn(). On some compilers,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3483you may also have to change the memory allocators (png_malloc, etc.).
3484
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3485.SS Configuring for compiler xxx:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3486
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]3487All includes for libpng are in pngconf.h. If you need to add, change
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3488or delete an include, this is the place to do it.
3489The includes that are not needed outside libpng are placed in pngpriv.h,
3490which is only used by the routines inside libpng itself.
3491The files in libpng proper only include pngpriv.h and png.h, which
3492in turn includes pngconf.h.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3493
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3494.SS Configuring zlib:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3495
3496There are special functions to configure the compression. Perhaps the
3497most useful one changes the compression level, which currently uses
3498input compression values in the range 0 - 9. The library normally
3499uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
3500have shown that for a large majority of images, compression values in
3501the range 3-6 compress nearly as well as higher levels, and do so much
3502faster. For online applications it may be desirable to have maximum speed
3503(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
3504specify no compression (Z_NO_COMPRESSION = 0), but this would create
3505files larger than just storing the raw bitmap. You can specify the
3506compression level by calling:
3507
3508 png_set_compression_level(png_ptr, level);
3509
3510Another useful one is to reduce the memory level used by the library.
3511The memory level defaults to 8, but it can be lowered if you are
3512short on memory (running DOS, for example, where you only have 640K).
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3513Note that the memory level does have an effect on compression; among
3514other things, lower levels will result in sections of incompressible
3515data being emitted in smaller stored blocks, with a correspondingly
3516larger relative overhead of up to 15% in the worst case.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3517
3518 png_set_compression_mem_level(png_ptr, level);
3519
3520The other functions are for configuring zlib. They are not recommended
3521for normal use and may result in writing an invalid PNG file. See
3522zlib.h for more information on what these mean.
3523
3524 png_set_compression_strategy(png_ptr,
3525 strategy);
3526 png_set_compression_window_bits(png_ptr,
3527 window_bits);
3528 png_set_compression_method(png_ptr, method);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3529 png_set_compression_buffer_size(png_ptr, size);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3530
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3531.SS Controlling row filtering
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3532
3533If you want to control whether libpng uses filtering or not, which
3534filters are used, and how it goes about picking row filters, you
3535can call one of these functions. The selection and configuration
3536of row filters can have a significant impact on the size and
3537encoding speed and a somewhat lesser impact on the decoding speed
3538of an image. Filtering is enabled by default for RGB and grayscale
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3539images (with and without alpha), but not for paletted images nor
3540for any images with bit depths less than 8 bits/pixel.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3541
3542The 'method' parameter sets the main filtering method, which is
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3543currently only '0' in the PNG 1.2 specification. The 'filters'
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3544parameter sets which filter(s), if any, should be used for each
3545scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
3546to turn filtering on and off, respectively.
3547
3548Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
3549PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3550ORed together with '|' to specify one or more filters to use.
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3551These filters are described in more detail in the PNG specification.
3552If you intend to change the filter type during the course of writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3553the image, you should start with flags set for all of the filters
3554you intend to use so that libpng can initialize its internal
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3555structures appropriately for all of the filter types. (Note that this
3556means the first row must always be adaptively filtered, because libpng
3557currently does not allocate the filter buffers until png_write_row()
3558is called for the first time.)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3559
3560 filters = PNG_FILTER_NONE | PNG_FILTER_SUB
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3561 PNG_FILTER_UP | PNG_FILTER_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3562 PNG_FILTER_PAETH | PNG_ALL_FILTERS;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3563
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3564 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
3565 filters);
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3566 The second parameter can also be
3567 PNG_INTRAPIXEL_DIFFERENCING if you are
3568 writing a PNG to be embedded in a MNG
3569 datastream. This parameter must be the
3570 same as the value of filter_method used
3571 in png_set_IHDR().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3572
3573It is also possible to influence how libpng chooses from among the
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3574available filters. This is done in one or both of two ways - by
3575telling it how important it is to keep the same filter for successive
3576rows, and by telling it the relative computational costs of the filters.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3577
3578 double weights[3] = {1.5, 1.3, 1.1},
3579 costs[PNG_FILTER_VALUE_LAST] =
3580 {1.0, 1.3, 1.3, 1.5, 1.7};
3581
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3582 png_set_filter_heuristics(png_ptr,
3583 PNG_FILTER_HEURISTIC_WEIGHTED, 3,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3584 weights, costs);
3585
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3586The weights are multiplying factors that indicate to libpng that the
3587row filter should be the same for successive rows unless another row filter
3588is that many times better than the previous filter. In the above example,
3589if 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]3590"sum of absolute differences" 1.5 x 1.3 times higher than other filters
3591and still be chosen, while the NONE filter could have a sum 1.1 times
3592higher than other filters and still be chosen. Unspecified weights are
3593taken to be 1.0, and the specified weights should probably be declining
3594like those above in order to emphasize recent filters over older filters.
3595
3596The filter costs specify for each filter type a relative decoding cost
3597to be considered when selecting row filters. This means that filters
3598with higher costs are less likely to be chosen over filters with lower
3599costs, unless their "sum of absolute differences" is that much smaller.
3600The costs do not necessarily reflect the exact computational speeds of
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3601the various filters, since this would unduly influence the final image
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3602size.
3603
3604Note that the numbers above were invented purely for this example and
3605are given only to help explain the function usage. Little testing has
3606been done to find optimum values for either the costs or the weights.
3607
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3608.SS Removing unwanted object code
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3609
3610There are a bunch of #define's in pngconf.h that control what parts of
3611libpng are compiled. All the defines end in _SUPPORTED. If you are
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3612never going to use a capability, you can change the #define to #undef
3613before recompiling libpng and save yourself code and data space, or
3614you can turn off individual capabilities with defines that begin with
3615PNG_NO_.
3616
3617You can also turn all of the transforms and ancillary chunk capabilities
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3618off en masse with compiler directives that define
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3619PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
3620or all four,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3621along with directives to turn on any of the capabilities that you do
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3622want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the extra
3623transformations but still leave the library fully capable of reading
3624and writing PNG files with all known public chunks. Use of the
3625PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
3626that is incapable of reading or writing ancillary chunks. If you are
3627not using the progressive reading capability, you can turn that off
3628with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
3629capability, which you'll still have).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3630
3631All the reading and writing specific code are in separate files, so the
3632linker should only grab the files it needs. However, if you want to
3633make sure, or if you are building a stand alone library, all the
3634reading files start with pngr and all the writing files start with
3635pngw. The files that don't match either (like png.c, pngtrans.c, etc.)
3636are used for both reading and writing, and always need to be included.
3637The progressive reader is in pngpread.c
3638
3639If you are creating or distributing a dynamically linked library (a .so
3640or DLL file), you should not remove or disable any parts of the library,
3641as this will cause applications linked with different versions of the
3642library to fail if they call functions not available in your library.
3643The size of the library itself should not be an issue, because only
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3644those sections that are actually used will be loaded into memory.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3645
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3646.SS Requesting debug printout
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3647
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3648The macro definition PNG_DEBUG can be used to request debugging
3649printout. Set it to an integer value in the range 0 to 3. Higher
3650numbers result in increasing amounts of debugging information. The
3651information is printed to the "stderr" file, unless another file
3652name is specified in the PNG_DEBUG_FILE macro definition.
3653
3654When PNG_DEBUG > 0, the following functions (macros) become available:
3655
3656 png_debug(level, message)
3657 png_debug1(level, message, p1)
3658 png_debug2(level, message, p1, p2)
3659
3660in which "level" is compared to PNG_DEBUG to decide whether to print
3661the message, "message" is the formatted string to be printed,
3662and p1 and p2 are parameters that are to be embedded in the string
3663according to printf-style formatting directives. For example,
3664
3665 png_debug1(2, "foo=%d\n", foo);
3666
3667is expanded to
3668
3669 if(PNG_DEBUG > 2)
3670 fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
3671
3672When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
3673can still use PNG_DEBUG to control your own debugging:
3674
3675 #ifdef PNG_DEBUG
3676 fprintf(stderr, ...
3677 #endif
3678
3679When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
3680having level = 0 will be printed. There aren't any such statements in
3681this version of libpng, but if you insert some they will be printed.
3682
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]3683.SH VI. MNG support
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]3684
3685The MNG specification (available at http://www.libpng.org/pub/mng) allows
3686certain extensions to PNG for PNG images that are embedded in MNG datastreams.
3687Libpng can support some of these extensions. To enable them, use the
3688png_permit_mng_features() function:
3689
3690 feature_set = png_permit_mng_features(png_ptr, mask)
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3691 mask is a png_uint_32 containing the bitwise OR of the
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]3692 features you want to enable. These include
3693 PNG_FLAG_MNG_EMPTY_PLTE
3694 PNG_FLAG_MNG_FILTER_64
3695 PNG_ALL_MNG_FEATURES
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3696 feature_set is a png_uint_32 that is the bitwise AND of
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]3697 your mask with the set of MNG features that is
3698 supported by the version of libpng that you are using.
3699
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3700It is an error to use this function when reading or writing a standalone
3701PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
Glenn Randers-Pehrsonf05f8032000-12-23 14:27:39 -0600[diff] [blame]3702in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
3703and the MHDR and MEND chunks. Libpng does not provide support for these
3704or any other MNG chunks; your application must provide its own support for
3705them. You may wish to consider using libmng (available at
3706http://www.libmng.com) instead.
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3707
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3708.SH VII. Changes to Libpng from version 0.88
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3709
3710It should be noted that versions of libpng later than 0.96 are not
3711distributed by the original libpng author, Guy Schalnat, nor by
3712Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
3713distributed versions 0.89 through 0.96, but rather by another member
3714of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
3715still alive and well, but they have moved on to other things.
3716
3717The old libpng functions png_read_init(), png_write_init(),
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]3718png_info_init(), png_read_destroy(), and png_write_destroy() have been
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]3719moved to PNG_INTERNAL in version 0.95 to discourage their use. These
3720functions will be removed from libpng version 2.0.0.
3721
3722The preferred method of creating and initializing the libpng structures is
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3723via the png_create_read_struct(), png_create_write_struct(), and
3724png_create_info_struct() because they isolate the size of the structures
3725from the application, allow version error checking, and also allow the
3726use of custom error handling routines during the initialization, which
3727the old functions do not. The functions png_read_destroy() and
3728png_write_destroy() do not actually free the memory that libpng
3729allocated for these structs, but just reset the data structures, so they
3730can be used instead of png_destroy_read_struct() and
3731png_destroy_write_struct() if you feel there is too much system overhead
3732allocating and freeing the png_struct for each image read.
3733
3734Setting the error callbacks via png_set_message_fn() before
3735png_read_init() as was suggested in libpng-0.88 is no longer supported
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3736because this caused applications that do not use custom error functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3737to fail if the png_ptr was not initialized to zero. It is still possible
3738to set the error callbacks AFTER png_read_init(), or to change them with
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]3739png_set_error_fn(), which is essentially the same function, but with a new
3740name to force compilation errors with applications that try to use the old
3741method.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3742
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3743Starting with version 1.0.7, you can find out which version of the library
3744you are using at run-time:
3745
3746 png_uint_32 libpng_vn = png_access_version_number();
3747
3748The number libpng_vn is constructed from the major version, minor
3749version with leading zero, and release number with leading zero,
3750(e.g., libpng_vn for version 1.0.7 is 10007).
3751
3752You can also check which version of png.h you used when compiling your
3753application:
3754
3755 png_uint_32 application_vn = PNG_LIBPNG_VER;
3756
Glenn Randers-Pehrson86f88dd2010-03-08 21:28:21 -0600[diff] [blame]3757%10%.SH VIII. (Omitted).
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3758.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]3759
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3760Support for user memory management was enabled by default. To
3761accomplish this, the functions png_create_read_struct_2(),
3762png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
3763png_malloc_default(), and png_free_default() were added.
3764
Glenn Randers-Pehrsond6ea40a2009-11-02 07:32:00 -0600[diff] [blame]3765Support for the iTXt chunk has been enabled by default as of
3766version 1.2.41.
3767
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3768Support for certain MNG features was enabled.
3769
3770Support for numbered error messages was added. However, we never got
3771around to actually numbering the error messages. The function
3772png_set_strip_error_numbers() was added (Note: the prototype for this
3773function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
3774builds of libpng-1.2.15. It was restored in libpng-1.2.36).
3775
3776The png_malloc_warn() function was added at libpng-1.2.3. This issues
3777a png_warning and returns NULL instead of aborting when it fails to
3778acquire the requested memory allocation.
3779
3780Support for setting user limits on image width and height was enabled
3781by default. The functions png_set_user_limits(), png_get_user_width_max(),
3782and png_get_user_height_max() were added at libpng-1.2.6.
3783
3784The png_set_add_alpha() function was added at libpng-1.2.7.
3785
3786The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
3787Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
3788tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
3789deprecated.
3790
3791A number of macro definitions in support of runtime selection of
3792assembler code features (especially Intel MMX code support) were
3793added at libpng-1.2.0:
3794
3795 PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
3796 PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
3797 PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
3798 PNG_ASM_FLAG_MMX_READ_INTERLACE
3799 PNG_ASM_FLAG_MMX_READ_FILTER_SUB
3800 PNG_ASM_FLAG_MMX_READ_FILTER_UP
3801 PNG_ASM_FLAG_MMX_READ_FILTER_AVG
3802 PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
3803 PNG_ASM_FLAGS_INITIALIZED
3804 PNG_MMX_READ_FLAGS
3805 PNG_MMX_FLAGS
3806 PNG_MMX_WRITE_FLAGS
3807 PNG_MMX_FLAGS
3808
3809We added the following functions in support of runtime
3810selection of assembler code features:
3811
3812 png_get_mmx_flagmask()
3813 png_set_mmx_thresholds()
3814 png_get_asm_flags()
3815 png_get_mmx_bitdepth_threshold()
3816 png_get_mmx_rowbytes_threshold()
3817 png_set_asm_flags()
3818
3819We replaced all of these functions with simple stubs in libpng-1.2.20,
3820when the Intel assembler code was removed due to a licensing issue.
3821
Glenn Randers-Pehrson3d893a02009-08-31 13:32:46 -0500[diff] [blame]3822These macros are deprecated:
3823
3824 PNG_READ_TRANSFORMS_NOT_SUPPORTED
3825 PNG_PROGRESSIVE_READ_NOT_SUPPORTED
3826 PNG_NO_SEQUENTIAL_READ_SUPPORTED
3827 PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
3828 PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
3829 PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
3830
3831They have been replaced, respectively, by:
3832
3833 PNG_NO_READ_TRANSFORMS
3834 PNG_NO_PROGRESSIVE_READ
3835 PNG_NO_SEQUENTIAL_READ
3836 PNG_NO_WRITE_TRANSFORMS
3837 PNG_NO_READ_ANCILLARY_CHUNKS
3838 PNG_NO_WRITE_ANCILLARY_CHUNKS
3839
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3840PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
3841deprecated since libpng-1.0.16 and libpng-1.2.6.
3842
3843The function
3844 png_check_sig(sig, num)
3845was replaced with
3846 !png_sig_cmp(sig, 0, num)
3847It has been deprecated since libpng-0.90.
3848
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3849The function
3850 png_set_gray_1_2_4_to_8()
3851which also expands tRNS to alpha was replaced with
3852 png_set_expand_gray_1_2_4_to_8()
3853which 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]3854
Glenn Randers-Pehrsond740c842009-11-04 19:01:54 -0600[diff] [blame]3855.SH IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
3856
3857Private libpng prototypes and macro definitions were moved from
3858png.h and pngconf.h into a new pngpriv.h header file.
3859
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3860Functions png_set_benign_errors(), png_benign_error(), and
3861png_chunk_benign_error() were added.
3862
3863Support for setting the maximum amount of memory that the application
3864will allocate for reading chunks was added, as a security measure.
3865The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
3866were added to the library.
3867
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]3868We implemented support for I/O states by adding png_ptr member io_state
3869and 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]3870
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]3871We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
3872input transforms.
3873
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]3874Checking for and reporting of errors in the IHDR chunk is more thorough.
3875
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]3876Support for global arrays was removed, to improve thread safety.
3877
3878Some obsolete/deprecated macros and functions have been removed.
3879
3880Typecasted NULL definitions such as
3881 #define png_voidp_NULL (png_voidp)NULL
3882were eliminated. If you used these in your application, just use
3883NULL instead.
3884
3885The png_struct and info_struct members "trans" and "trans_values" were
3886changed to "trans_alpha" and "trans_color", respectively.
3887
3888The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]3889were removed.
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]3890
3891The PNG_1_0_X and PNG_1_2_X macros were eliminated.
3892
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]3893The PNG_LEGACY_SUPPORTED macro was eliminated.
3894
3895Many WIN32_WCE #ifdefs were removed.
3896
3897The functions png_read_init(info_ptr), png_write_init(info_ptr),
3898png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
3899have been removed. They have been deprecated since libpng-0.95.
3900
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3901The png_permit_empty_plte() was removed. It has been deprecated
3902since libpng-1.0.9. Use png_permit_mng_features() instead.
3903
3904We removed the obsolete stub functions png_get_mmx_flagmask(),
3905png_set_mmx_thresholds(), png_get_asm_flags(),
3906png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
3907png_set_asm_flags(), and png_mmx_supported()
3908
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]3909We removed the obsolete png_check_sig(), png_memcpy_check(), and
3910png_memset_check() functions. Instead use !png_sig_cmp(), png_memcpy(),
3911and png_memset(), respectively.
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3912
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]3913The function png_set_gray_1_2_4_to_8() was removed. It has been
3914deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
3915png_set_expand_gray_1_2_4_to_8() because the former function also
3916expanded palette images.
3917
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3918We changed the prototype for png_malloc() from
3919 png_malloc(png_structp png_ptr, png_uint_32 size)
3920to
3921 png_malloc(png_structp png_ptr, png_alloc_size_t size)
3922
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]3923This also applies to the prototype for the user replacement malloc_fn().
3924
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]3925The png_calloc() function was added and is used in place of
3926of "png_malloc(); png_memset();" except in the case in png_read_png()
3927where the array consists of pointers; in this case a "for" loop is used
3928after the png_malloc() to set the pointers to NULL, to give robust.
3929behavior in case the application runs out of memory part-way through
3930the process.
3931
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3932We changed the prototypes of png_get_compression_buffer_size() and
3933png_set_compression_buffer_size() to work with png_size_t instead of
3934png_uint_32.
3935
Glenn Randers-Pehrson45af8192009-12-30 08:37:29 -0600[diff] [blame]3936Support for numbered error messages was removed by default, since we
3937never got around to actually numbering the error messages. The function
3938png_set_strip_error_numbers() was removed from the library by default.
3939
3940The png_zalloc() and png_zfree() functions are no longer exported.
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3941The png_zalloc() function no longer zeroes out the memory that it
3942allocates.
3943
Glenn Randers-Pehrson3cd7cff2010-04-16 19:27:08 -0500[diff] [blame]3944Support for dithering was disabled by default in libpng-1.4.0, because
3945been well tested and doesn't actually "dither". The code was not
3946removed, however, and could be enabled by building libpng with
3947PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
3948was reenabled, but the function was renamed png_set_quantize() to
3949reflect more accurately what it actually does. At the same time,
3950the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
3951PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS.
Glenn Randers-Pehrson60988072010-04-13 22:11:06 -0500[diff] [blame]3952
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3953We removed the trailing '.' from the warning and error messages.
3954
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3955.SH X. Detecting libpng
3956
3957The png_get_io_ptr() function has been present since libpng-0.88, has never
3958changed, and is unaffected by conditional compilation macros. It is the
3959best choice for use in configure scripts for detecting the presence of any
Glenn Randers-Pehrson99708d52009-06-29 17:30:00 -0500[diff] [blame]3960libpng version since 0.88. In an autoconf "configure.in" you could use
3961
3962 AC_CHECK_LIB(png, png_get_io_ptr, ...
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3963
3964.SH XI. Source code repository
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3965
3966Since about February 2009, version 1.2.34, libpng has been under "git" source
3967control. The git repository was built from old libpng-x.y.z.tar.gz files
3968going back to version 0.70. You can access the git repository (read only)
3969at
3970
3971 git://libpng.git.sourceforge.net/gitroot/libpng
3972
3973or you can browse it via "gitweb" at
3974
3975 http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng
3976
3977Patches can be sent to glennrp at users.sourceforge.net or to
3978png-mng-implement at lists.sourceforge.net or you can upload them to
3979the libpng bug tracker at
3980
3981 http://libpng.sourceforge.net
3982
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3983.SH XII. Coding style
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3984
3985Our coding style is similar to the "Allman" style, with curly
3986braces on separate lines:
3987
3988 if (condition)
3989 {
3990 action;
3991 }
3992
3993 else if (another condition)
3994 {
3995 another action;
3996 }
3997
3998The braces can be omitted from simple one-line actions:
3999
4000 if (condition)
4001 return (0);
4002
4003We use 3-space indentation, except for continued statements which
4004are usually indented the same as the first line of the statement
4005plus four more spaces.
4006
Glenn Randers-Pehrson5ade7ed2009-09-30 15:11:49 -0500[diff] [blame]4007For macro definitions we use 2-space indentation, always leaving the "#"
4008in the first column.
4009
4010 #ifndef PNG_NO_FEATURE
4011 # ifndef PNG_FEATURE_SUPPORTED
4012 # define PNG_FEATURE_SUPPORTED
4013 # endif
4014 #endif
4015
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4016Comments appear with the leading "/*" at the same indentation as
4017the statement that follows the comment:
4018
4019 /* Single-line comment */
4020 statement;
4021
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]4022 /* This is a multiple-line
4023 * comment.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4024 */
4025 statement;
4026
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]4027Very short comments can be placed after the end of the statement
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4028to which they pertain:
4029
4030 statement; /* comment */
4031
4032We don't use C++ style ("//") comments. We have, however,
4033used them in the past in some now-abandoned MMX assembler
4034code.
4035
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame]4036Functions and their curly braces are not indented, and
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4037exported functions are marked with PNGAPI:
4038
4039 /* This is a public function that is visible to
4040 * application programers. It does thus-and-so.
4041 */
4042 void PNGAPI
4043 png_exported_function(png_ptr, png_info, foo)
4044 {
4045 body;
4046 }
4047
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]4048The prototypes for all exported functions appear in png.h,
4049above the comment that says
4050
4051 /* Maintainer: Put new public prototypes here ... */
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4052
4053We mark all non-exported functions with "/* PRIVATE */"":
4054
4055 void /* PRIVATE */
4056 png_non_exported_function(png_ptr, png_info, foo)
4057 {
4058 body;
4059 }
4060
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]4061The prototypes for non-exported functions (except for those in
Glenn Randers-Pehrson5df7edb2009-10-29 23:32:44 -0500[diff] [blame]4062pngtest) appear in
4063pngpriv.h
Glenn Randers-Pehrson416976f2009-07-27 22:16:09 -0500[diff] [blame]4064above the comment that says
4065
4066 /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4067
4068The names of all exported functions and variables begin
4069with "png_", and all publicly visible C preprocessor
4070macros begin with "PNG_".
4071
4072We put a space after each comma and after each semicolon
4073in "for" statments, and we put spaces before and after each
Glenn Randers-Pehrsone4c706a2010-03-06 14:51:54 -0600[diff] [blame]4074C binary operator and after "for" or "while", and before
4075"?". We don't put a space between a typecast and the expression
4076being cast, nor do we put one between a function name and the
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4077left parenthesis that follows it:
4078
4079 for (i = 2; i > 0; --i)
Glenn Randers-Pehrson67f3b482009-09-23 11:36:28 -0500[diff] [blame]4080 y[i] = a(x) + (int)b;
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4081
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]4082We prefer #ifdef and #ifndef to #if defined() and if !defined()
4083when there is only one macro being tested.
4084
Glenn Randers-Pehrson67f3b482009-09-23 11:36:28 -0500[diff] [blame]4085We do not use the TAB character for indentation in the C sources.
4086
Glenn Randers-Pehrson62ca98e2009-12-20 15:14:57 -0600[diff] [blame]4087Lines do not exceed 80 characters.
4088
Glenn Randers-Pehrsonf210a052009-11-12 10:02:24 -0600[diff] [blame]4089Other rules can be inferred by inspecting the libpng source.
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4090
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]4091.SH XIII. Y2K Compliance in libpng
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]4092
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]4093June 19, 2010
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4094
4095Since the PNG Development group is an ad-hoc body, we can't make
4096an official declaration.
4097
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4098This is your unofficial assurance that libpng from version 0.71 and
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]4099upward through 1.5.0beta26 are Y2K compliant. It is my belief that earlier
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4100versions were also Y2K compliant.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4101
4102Libpng only has three year fields. One is a 2-byte unsigned integer that
4103will hold years up to 65535. The other two hold the date in text
4104format, and will hold years up to 9999.
4105
4106The integer is
4107 "png_uint_16 year" in png_time_struct.
4108
4109The strings are
4110 "png_charp time_buffer" in png_struct and
4111 "near_time_buffer", which is a local character string in png.c.
4112
4113There are seven time-related functions:
4114
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4115 png_convert_to_rfc_1123() in png.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4116 (formerly png_convert_to_rfc_1152() in error)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4117 png_convert_from_struct_tm() in pngwrite.c, called
4118 in pngwrite.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4119 png_convert_from_time_t() in pngwrite.c
4120 png_get_tIME() in pngget.c
4121 png_handle_tIME() in pngrutil.c, called in pngread.c
4122 png_set_tIME() in pngset.c
4123 png_write_tIME() in pngwutil.c, called in pngwrite.c
4124
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4125All appear to handle dates properly in a Y2K environment. The
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4126png_convert_from_time_t() function calls gmtime() to convert from system
4127clock time, which returns (year - 1900), which we properly convert to
4128the full 4-digit year. There is a possibility that applications using
4129libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4130function, or that they are incorrectly passing only a 2-digit year
4131instead of "year - 1900" into the png_convert_from_struct_tm() function,
4132but this is not under our control. The libpng documentation has always
4133stated that it works with 4-digit years, and the APIs have been
4134documented as such.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4135
4136The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
4137integer to hold the year, and can hold years as large as 65535.
4138
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4139zlib, upon which libpng depends, is also Y2K compliant. It contains
4140no date-related code.
4141
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4142
4143 Glenn Randers-Pehrson
4144 libpng maintainer
4145 PNG Development Group
4146
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4147.SH NOTE
4148
4149Note about libpng version numbers:
4150
4151Due to various miscommunications, unforeseen code incompatibilities
4152and occasional factors outside the authors' control, version numbering
4153on the library has not always been consistent and straightforward.
4154The following table summarizes matters since version 0.89c, which was
4155the first widely used release:
4156
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4157 source png.h png.h shared-lib
4158 version string int version
4159 ------- ------ ----- ----------
4160 0.89c ("beta 3") 0.89 89 1.0.89
4161 0.90 ("beta 4") 0.90 90 0.90
4162 0.95 ("beta 5") 0.95 95 0.95
4163 0.96 ("beta 6") 0.96 96 0.96
4164 0.97b ("beta 7") 1.00.97 97 1.0.1
4165 0.97c 0.97 97 2.0.97
4166 0.98 0.98 98 2.0.98
4167 0.99 0.99 98 2.0.99
4168 0.99a-m 0.99 99 2.0.99
4169 1.00 1.00 100 2.1.0
4170 1.0.0 1.0.0 100 2.1.0
4171 1.0.0 (from here on, the 100 2.1.0
4172 1.0.1 png.h string is 10001 2.1.0
4173 1.0.1a-e identical to the 10002 from here on, the
4174 1.0.2 source version) 10002 shared library is 2.V
4175 1.0.2a-b 10003 where V is the source
4176 1.0.1 10001 code version except as
4177 1.0.1a-e 10002 2.1.0.1a-e noted.
4178 1.0.2 10002 2.1.0.2
4179 1.0.2a-b 10003 2.1.0.2a-b
4180 1.0.3 10003 2.1.0.3
4181 1.0.3a-d 10004 2.1.0.3a-d
4182 1.0.4 10004 2.1.0.4
4183 1.0.4a-f 10005 2.1.0.4a-f
4184 1.0.5 (+ 2 patches) 10005 2.1.0.5
4185 1.0.5a-d 10006 2.1.0.5a-d
4186 1.0.5e-r 10100 2.1.0.5e-r
4187 1.0.5s-v 10006 2.1.0.5s-v
4188 1.0.6 (+ 3 patches) 10006 2.1.0.6
4189 1.0.6d-g 10007 2.1.0.6d-g
4190 1.0.6h 10007 10.6h
4191 1.0.6i 10007 10.6i
4192 1.0.6j 10007 2.1.0.6j
4193 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14
4194 1.0.7beta15-18 1 10007 2.1.0.7beta15-18
4195 1.0.7rc1-2 1 10007 2.1.0.7rc1-2
4196 1.0.7 1 10007 2.1.0.7
4197 1.0.8beta1-4 1 10008 2.1.0.8beta1-4
4198 1.0.8rc1 1 10008 2.1.0.8rc1
4199 1.0.8 1 10008 2.1.0.8
4200 1.0.9beta1-6 1 10009 2.1.0.9beta1-6
4201 1.0.9rc1 1 10009 2.1.0.9rc1
4202 1.0.9beta7-10 1 10009 2.1.0.9beta7-10
4203 1.0.9rc2 1 10009 2.1.0.9rc2
4204 1.0.9 1 10009 2.1.0.9
Glenn Randers-Pehrsone1644472001-03-23 05:06:56 -0600[diff] [blame]4205 1.0.10beta1 1 10010 2.1.0.10beta1
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4206 1.0.10rc1 1 10010 2.1.0.10rc1
Glenn Randers-Pehrson13cfbac2001-03-30 06:42:28 -0600[diff] [blame]4207 1.0.10 1 10010 2.1.0.10
Glenn Randers-Pehrsone1eff582001-04-14 20:15:41 -0500[diff] [blame]4208 1.0.11beta1-3 1 10011 2.1.0.11beta1-3
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]4209 1.0.11rc1 1 10011 2.1.0.11rc1
Glenn Randers-Pehrson32835392001-04-27 08:29:32 -0500[diff] [blame]4210 1.0.11 1 10011 2.1.0.11
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]4211 1.0.12beta1-2 2 10012 2.1.0.12beta1-2
4212 1.0.12rc1 2 10012 2.1.0.12rc1
4213 1.0.12 2 10012 2.1.0.12
4214 1.1.0a-f - 10100 2.1.1.0a-f abandoned
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]4215 1.2.0beta1-2 2 10200 2.1.2.0beta1-2
Glenn Randers-Pehrson5a0be342001-10-18 20:55:13 -0500[diff] [blame]4216 1.2.0beta3-5 3 10200 3.1.2.0beta3-5
4217 1.2.0rc1 3 10200 3.1.2.0rc1
4218 1.2.0 3 10200 3.1.2.0
Glenn Randers-Pehrson5cded0b2001-11-07 07:10:08 -0600[diff] [blame]4219 1.2.1beta-4 3 10201 3.1.2.1beta1-4
Glenn Randers-Pehrsondb3b88d2001-12-04 06:30:43 -0600[diff] [blame]4220 1.2.1rc1-2 3 10201 3.1.2.1rc1-2
4221 1.2.1 3 10201 3.1.2.1
Glenn Randers-Pehrson25228ab2002-03-31 07:33:55 -0600[diff] [blame]4222 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6
Glenn Randers-Pehrsonfcbd7872002-04-07 16:35:38 -0500[diff] [blame]4223 1.0.13beta1 10 10013 10.so.0.1.0.13beta1
4224 1.0.13rc1 10 10013 10.so.0.1.0.13rc1
4225 1.2.2rc1 12 10202 12.so.0.1.2.2rc1
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4226 1.0.13 10 10013 10.so.0.1.0.13
4227 1.2.2 12 10202 12.so.0.1.2.2
Glenn Randers-Pehrson22f28962002-05-13 18:17:09 -0500[diff] [blame]4228 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6
4229 1.2.3 12 10203 12.so.0.1.2.3
Glenn Randers-Pehrsond020e9d2002-06-28 09:34:00 -0500[diff] [blame]4230 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3
Glenn Randers-Pehrson2ae022d2002-07-01 22:23:46 -0500[diff] [blame]4231 1.2.4rc1 13 10204 12.so.0.1.2.4rc1
Glenn Randers-Pehrson484a8a12002-07-07 19:15:20 -0500[diff] [blame]4232 1.0.14 10 10014 10.so.0.1.0.14
4233 1.2.4 13 10204 12.so.0.1.2.4
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]4234 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2
4235 1.0.15rc1 10 10015 10.so.0.1.0.15rc1
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4236 1.0.15 10 10015 10.so.0.1.0.15
4237 1.2.5 13 10205 12.so.0.1.2.5
4238 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4
Glenn Randers-Pehrson37f116a2004-08-15 07:15:39 -0500[diff] [blame]4239 1.2.6rc1-5 13 10206 12.so.0.1.2.6rc1-5
4240 1.0.16 10 10016 10.so.0.1.0.16
4241 1.2.6 13 10206 12.so.0.1.2.6
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]4242 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]4243 1.0.17rc1 10 10017 12.so.0.1.0.17rc1
4244 1.2.7rc1 13 10207 12.so.0.1.2.7rc1
Glenn Randers-Pehrson250dfe12004-09-11 21:19:54 -0500[diff] [blame]4245 1.0.17 10 10017 12.so.0.1.0.17
4246 1.2.7 13 10207 12.so.0.1.2.7
Glenn Randers-Pehrson40936072004-11-20 11:18:40 -0600[diff] [blame]4247 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5
Glenn Randers-Pehrson584b96e2004-11-29 15:08:00 -0600[diff] [blame]4248 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5
4249 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5
Glenn Randers-Pehrson917648e2004-12-02 18:14:51 -0600[diff] [blame]4250 1.0.18 10 10018 12.so.0.1.0.18
4251 1.2.8 13 10208 12.so.0.1.2.8
Glenn Randers-Pehrsone6474622006-03-04 16:50:47 -0600[diff] [blame]4252 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3
Glenn Randers-Pehrson4deeb792006-03-22 16:21:59 -0600[diff] [blame]4253 1.2.9beta4-11 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrson3a512032006-03-31 05:29:33 -0600[diff] [blame]4254 1.2.9rc1 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsona7d0c942006-04-14 06:22:52 -0500[diff] [blame]4255 1.2.9 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]4256 1.2.10beta1-7 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson17218292006-04-20 07:20:46 -0500[diff] [blame]4257 1.2.10rc1-2 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson86dc9812006-05-10 07:27:44 -0500[diff] [blame]4258 1.2.10 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]4259 1.4.0beta1-6 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrsond60c8862009-06-15 21:56:14 -0500[diff] [blame]4260 1.2.11beta1-4 13 10210 12.so.0.11[.0]
Glenn Randers-Pehrson3424ee72006-07-12 13:33:47 -0500[diff] [blame]4261 1.4.0beta7-8 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrson701dbaa2006-11-17 09:36:54 -0600[diff] [blame]4262 1.2.11 13 10211 12.so.0.11[.0]
4263 1.2.12 13 10212 12.so.0.12[.0]
4264 1.4.0beta9-14 14 10400 14.so.0.0[.0]
4265 1.2.13 13 10213 12.so.0.13[.0]
Glenn Randers-Pehrson97a9b482008-10-25 20:03:28 -0500[diff] [blame]4266 1.4.0beta15-36 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrsonfa028102009-10-10 06:15:21 -0500[diff] [blame]4267 1.4.0beta37-87 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson733da8c2009-10-30 00:00:15 -0500[diff] [blame]4268 1.4.0rc01 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson62ca98e2009-12-20 15:14:57 -0600[diff] [blame]4269 1.4.0beta88-109 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrson67a83db2010-01-01 18:26:18 -0600[diff] [blame]4270 1.4.0rc02-08 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsondbcfb712009-12-25 14:24:18 -0600[diff] [blame]4271 1.4.0 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsone3f3c4e2010-02-07 18:08:50 -0600[diff] [blame]4272 1.4.1beta01-03 14 10401 14.so.14.1[.0]
4273 1.4.1rc01 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrson7a5be532010-02-14 07:16:19 -0600[diff] [blame]4274 1.4.1beta04-12 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrsonaaf377c2010-03-08 11:20:30 -0600[diff] [blame]4275 1.4.1 14 10401 14.so.14.1[.0]
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]4276 1.4.2 14 10402 14.so.14.2[.0]
4277 1.4.3 14 10403 14.so.14.3[.0]
4278 1.5.0beta01-26 15 10500 15.so.15.1[.0]
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4279
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4280Henceforth the source version will match the shared-library minor
4281and patch numbers; the shared-library major version number will be
4282used for changes in backward compatibility, as it is intended. The
4283PNG_PNGLIB_VER macro, which is not used within libpng but is available
4284for applications, is an unsigned integer of the form xyyzz corresponding
4285to 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]4286were given the previous public release number plus a letter, until
4287version 1.0.6j; from then on they were given the upcoming public
4288release number plus "betaNN" or "rcN".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4289
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4290.SH "SEE ALSO"
Glenn Randers-Pehrson4e763f12010-03-03 10:45:50 -0600[diff] [blame]4291.BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
Glenn Randers-Pehrson7fb32a82010-03-03 09:47:49 -0600[diff] [blame]4292
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4293.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4294.IR libpng :
4295.IP
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]4296http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]4297http://www.libpng.org/pub/png
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4298
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4299.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4300.IR zlib :
4301.IP
4302(generally) at the same location as
4303.I libpng
4304or at
4305.br
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]4306ftp://ftp.info-zip.org/pub/infozip/zlib
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4307
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4308.LP
4309.IR PNG specification: RFC 2083
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4310.IP
4311(generally) at the same location as
4312.I libpng
4313or at
4314.br
4315ftp://ds.internic.net/rfc/rfc2083.txt
4316.br
4317or (as a W3C Recommendation) at
4318.br
4319http://www.w3.org/TR/REC-png.html
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4320
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4321.LP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4322In the case of any inconsistency between the PNG specification
4323and this library, the specification takes precedence.
4324
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4325.SH AUTHORS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4326This man page: Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]4327<glennrp at users.sourceforge.net>
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4328
4329The contributing authors would like to thank all those who helped
4330with testing, bug fixes, and patience. This wouldn't have been
4331possible without all of you.
4332
4333Thanks to Frank J. T. Wojcik for helping with the documentation.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4334
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]4335Libpng version 1.5.0beta26 - June 19, 2010:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4336Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]4337Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4338
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4339Supported by the PNG development group
4340.br
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]4341png-mng-implement at lists.sf.net
4342(subscription required; visit
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]4343png-mng-implement at lists.sourceforge.net (subscription required; visit
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]4344https://lists.sourceforge.net/lists/listinfo/png-mng-implement
4345to subscribe).
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4346
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4347.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4348
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]4349(This copy of the libpng notices is provided for your convenience. In case of
4350any discrepancy between this copy and the notices in the file png.h that is
4351included in the libpng distribution, the latter shall prevail.)
4352
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4353If you modify libpng you may insert additional notices immediately following
4354this sentence.
4355
Glenn Randers-Pehrsonbfbf8652009-06-26 21:46:52 -0500[diff] [blame]4356This code is released under the libpng license.
Glenn Randers-Pehrson037023b2009-06-24 10:27:36 -0500[diff] [blame]4357
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]4358libpng versions 1.2.6, August 15, 2004, through 1.5.0beta26, June 19, 2010, are
Glenn Randers-Pehrsona7dbcba2007-05-15 16:16:34 -0500[diff] [blame]4359Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4360distributed according to the same disclaimer and license as libpng-1.2.5
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]4361with the following individual added to the list of Contributing Authors
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4362
4363 Cosmin Truta
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4364
4365libpng 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]4366Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson32fc5ce2000-07-24 06:34:14 -0500[diff] [blame]4367distributed according to the same disclaimer and license as libpng-1.0.6
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4368with the following individuals added to the list of Contributing Authors
4369
4370 Simon-Pierre Cadieux
4371 Eric S. Raymond
4372 Gilles Vollant
4373
4374and with the following additions to the disclaimer:
4375
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4376 There is no warranty against interference with your
4377 enjoyment of the library or against infringement.
4378 There is no warranty that our efforts or the library
4379 will fulfill any of your particular purposes or needs.
4380 This library is provided with all faults, and the entire
4381 risk of satisfactory quality, performance, accuracy, and
4382 effort is with the user.
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4383
4384libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
4385Copyright (c) 1998, 1999 Glenn Randers-Pehrson
4386Distributed according to the same disclaimer and license as libpng-0.96,
4387with the following individuals added to the list of Contributing Authors:
4388
4389 Tom Lane
4390 Glenn Randers-Pehrson
4391 Willem van Schaik
4392
4393libpng versions 0.89, June 1996, through 0.96, May 1997, are
Glenn Randers-Pehrson54a066a1999-09-19 06:04:18 -0500[diff] [blame]4394Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4395Distributed according to the same disclaimer and license as libpng-0.88,
4396with the following individuals added to the list of Contributing Authors:
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4397
4398 John Bowler
4399 Kevin Bracey
4400 Sam Bushell
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4401 Magnus Holmgren
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4402 Greg Roelofs
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4403 Tom Tanner
4404
4405libpng versions 0.5, May 1995, through 0.88, January 1996, are
4406Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
4407
4408For the purposes of this copyright and license, "Contributing Authors"
4409is defined as the following set of individuals:
4410
4411 Andreas Dilger
4412 Dave Martindale
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4413 Guy Eric Schalnat
4414 Paul Schmidt
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4415 Tim Wegner
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]4416
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4417The PNG Reference Library is supplied "AS IS". The Contributing Authors
4418and Group 42, Inc. disclaim all warranties, expressed or implied,
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4419including, without limitation, the warranties of merchantability and of
4420fitness for any purpose. The Contributing Authors and Group 42, Inc.
4421assume no liability for direct, indirect, incidental, special, exemplary,
4422or consequential damages, which may result from the use of the PNG
4423Reference Library, even if advised of the possibility of such damage.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4424
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4425Permission is hereby granted to use, copy, modify, and distribute this
4426source code, or portions hereof, for any purpose, without fee, subject
4427to the following restrictions:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4428
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]44291. The origin of this source code must not be misrepresented.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4430
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]44312. Altered versions must be plainly marked as such and
4432 must not be misrepresented as being the original source.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4433
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]44343. This Copyright notice may not be removed or altered from
4435 any source or altered source distribution.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4436
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4437The Contributing Authors and Group 42, Inc. specifically permit, without
4438fee, and encourage the use of this source code as a component to
4439supporting the PNG file format in commercial products. If you use this
4440source code in a product, acknowledgment is not required but would be
4441appreciated.
4442
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4443
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4444A "png_get_copyright" function is available, for convenient use in "about"
4445boxes and the like:
4446
4447 printf("%s",png_get_copyright(NULL));
4448
4449Also, the PNG logo (in PNG format, of course) is supplied in the
Glenn Randers-Pehrsona4d54bd2000-07-14 08:15:12 -0500[diff] [blame]4450files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4451
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4452Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4453certification mark of the Open Source Initiative.
4454
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4455Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]4456glennrp at users.sourceforge.net
Glenn Randers-Pehrson5b3d5542010-06-18 21:55:53 -0500[diff] [blame^]4457June 19, 2010
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4458
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4459.\" end of man page
4460