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gerrit-public.fairphone.software / platform / external / libpng / b5444a177905e7f6e56c11ef411fd89245eec4a8 / . / libpng.3
blob: 17e249eccfd26ce9b59b0ed8dc04f848df792f04 [file] [log] [blame]
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]1.TH LIBPNG 3 "June 8, 2009"
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]2.SH NAME
Glenn Randers-Pehrson7aa18342009-06-05 17:24:17 -0500[diff] [blame]3libpng \- Portable Network Graphics (PNG) Reference Library 1.4.0beta63
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4.SH SYNOPSIS
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -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-Pehrsonb5444a12009-06-08 08:36:19 -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-Pehrsonb5444a12009-06-08 08:36:19 -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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]21\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]23\fBint png_check_sig (png_bytep \fP\fIsig\fP\fB, int \fInum\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]24
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -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_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]28
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]29\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]31\fBvoid png_chunk_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]32
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -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_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]36
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]37\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]39\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]40
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]41\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]43\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]44
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]45\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]47\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]48
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]49\fI\fB
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Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]51\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]52
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]53\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]55\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]57\fI\fB
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Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]59\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]60
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]61\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]63\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]65\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]67\fBint png_debug(int \fP\fIlevel\fP\fB, png_const_charp \fImessage\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]69\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]71\fBint png_debug1(int \fP\fIlevel\fP\fB, png_const_charp \fP\fImessage\fP\fB, \fIp1\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]73\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]75\fBint png_debug2(int \fP\fIlevel\fP\fB, png_const_charp \fP\fImessage\fP\fB, \fP\fIp1\fP\fB, \fIp2\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]77\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]79\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]81\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]83\fBvoid png_destroy_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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]85\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]87\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]89\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]91\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]93\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]95\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]97\fI\fB
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Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]99\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]101\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]103\fBvoid png_free_default(png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]105\fI\fB
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Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]107\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]108
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]109\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]111\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]113\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]115\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-Pehrsonb5444a12009-06-08 08:36:19 -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_channels (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]121\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]123\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]125\fI\fB
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Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]127\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]129\fI\fB
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Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]131\fBpng_uint_32 png_get_chunk_cache_max (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]133\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]135\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]137\fI\fB
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Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]139\fBpng_uint_32 png_get_compression_buffer_size (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]141\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]143\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]145\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]147\fBpng_byte png_get_copyright (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]149\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]151\fBpng_voidp png_get_error_ptr (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -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_filter_type (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -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_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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]161\fI\fB
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Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]163\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]165\fI\fB
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Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]167\fBpng_byte png_get_header_ver (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]169\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]171\fBpng_byte png_get_header_version (png_structp \fIpng_ptr\fP\fB);\fP
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Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -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_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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]177\fI\fB
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Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]179\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]180
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]181\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]183\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]185\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]187\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]189\fI\fB
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Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]191\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]193\fI\fB
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195\fB#if \fI!defined(PNG_1_0_X)
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197\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
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199\fI\fB#endif
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201\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]202
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]203\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-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]205\fI\fB
206
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]207\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
208
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]209\fI\fB
210
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]211\fBpng_byte png_get_libpng_ver (png_structp \fIpng_ptr\fP\fB);\fP
212
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]213\fI\fB
214
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]215\fBpng_voidp png_get_mem_ptr(png_structp \fIpng_ptr\fP\fB);\fP
216
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]217\fI\fB
218
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]219\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
220
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]221\fI\fB
222
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]223\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
224
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]225\fI\fB
226
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]227\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
228
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]229\fI\fB
230
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]231\fBfloat png_get_pixel_aspect_ratio (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
232
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]233\fI\fB
234
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]235\fBpng_uint_32 png_get_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
236
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]237\fI\fB
238
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]239\fBpng_voidp png_get_progressive_ptr (png_structp \fIpng_ptr\fP\fB);\fP
240
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]241\fI\fB
242
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]243\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
244
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]245\fI\fB
246
247\fBpng_byte png_get_rgb_to_gray_status (png_structp \fIpng_ptr)
248
249\fBpng_uint_32 png_get_rowbytes (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
250
251\fI\fB
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]252
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]253\fBpng_bytepp png_get_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
254
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]255\fI\fB
256
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]257\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
258
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]259\fI\fB
260
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]261\fBpng_bytep png_get_signature (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
262
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]263\fI\fB
264
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]265\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]266
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]267\fI\fB
268
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]269\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
270
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]271\fI\fB
272
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]273\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
274
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]275\fI\fB
276
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]277\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
278
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]279\fI\fB
280
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]281\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]282
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]283\fI\fB
284
285\fB/* This function is really an inline macro. \fI*/
286
287\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
288
289\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]290
291\fBpng_uint_32 png_get_uint_31 (png_bytep \fIbuf\fP\fB);\fP
292
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]293\fI\fB
294
295\fB/* This function is really an inline macro. \fI*/
296
297\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
298
299\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]300
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]301\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
302
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]303\fI\fB
304
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]305\fBpng_voidp png_get_user_chunk_ptr (png_structp \fIpng_ptr\fP\fB);\fP
306
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]307\fI\fB
308
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]309\fBpng_uint_32 png_get_user_height_max( png_structp \fIpng_ptr\fP\fB);\fP
310
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]311\fI\fB
312
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]313\fBpng_voidp png_get_user_transform_ptr (png_structp \fIpng_ptr\fP\fB);\fP
314
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]315\fI\fB
316
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]317\fBpng_uint_32 png_get_user_width_max (png_structp \fIpng_ptr\fP\fB);\fP
318
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]319\fI\fB
320
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]321\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
322
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]323\fI\fB
324
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]325\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]326
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]327\fI\fB
328
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]329\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]330
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]331\fI\fB
332
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]333\fBpng_uint_32 png_get_x_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
334
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]335\fI\fB
336
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]337\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]338
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]339\fI\fB
340
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]341\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]342
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]343\fI\fB
344
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]345\fBpng_uint_32 png_get_y_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
346
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]347\fI\fB
348
Glenn Randers-Pehrsonc1bfe682002-03-06 22:08:00 -0600[diff] [blame]349\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
350
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]351\fI\fB
352
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]353\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]354
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]355\fI\fB
356
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]357\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]358
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]359\fI\fB
360
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]361\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]362
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]363\fI\fB
364
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]365\fBvoidp png_memcpy (png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_size_t \fIsize\fP\fB);\fP
366
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]367\fI\fB
368
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]369\fBvoidp png_memset (png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_size_t \fIsize\fP\fB);\fP
370
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]371\fI\fB
372
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]373\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
374
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]375\fI\fB
376
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]377\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
378
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]379\fI\fB
380
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]381\fBvoid png_read_destroy (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_infop \fIend_info_ptr\fP\fB);\fP
382
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]383\fI\fB
384
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]385\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
386
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]387\fI\fB
388
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]389\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
390
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]391\fI\fB
392
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]393\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
394
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]395\fI\fB
396
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]397\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]398
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]399\fI\fB
400
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]401\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
402
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]403\fI\fB
404
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]405\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
406
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]407\fI\fB
408
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]409\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
410
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]411\fI\fB
412
413\fB#if \fI!defined(PNG_1_0_X)
414
415\fBpng_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
416
417\fI\fB
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]418
419\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
420
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]421\fI\fB
422
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]423\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
424
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]425\fI\fB
426
427\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
428
429\fI\fB#endif
430
431\fI\fB
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]432
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]433\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
434
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]435\fI\fB
436
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]437\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
438
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]439\fI\fB
440
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]441\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
442
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]443\fI\fB
444
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]445\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
446
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]447\fI\fB
448
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]449\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
450
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]451\fI\fB
452
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]453\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
454
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]455\fI\fB
456
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]457\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
458
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]459\fI\fB
460
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]461\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
462
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]463\fI\fB
464
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]465\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
466
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]467\fI\fB
468
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]469\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]470
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]471\fI\fB
472
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]473\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]474
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]475\fI\fB
476
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]477\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]478
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]479\fI\fB
480
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]481\fBvoid png_set_dither (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_dither\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]482
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]483\fI\fB
484
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]485\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]486
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]487\fI\fB
488
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]489\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]490
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]491\fI\fB
492
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]493\fBvoid png_set_expand_gray_1_2_4_to_8(png_structp \fIpng_ptr\fP\fB);\fP
494
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]495\fI\fB
496
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]497\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]498
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]499\fI\fB
500
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]501\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]502
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]503\fI\fB
504
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]505\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]506
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]507\fI\fB
508
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]509\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]510
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]511\fI\fB
512
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]513\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]514
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]515\fI\fB
516
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]517\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]518
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]519\fI\fB
520
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]521\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
522
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]523\fI\fB
524
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]525\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]526
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]527\fI\fB
528
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]529\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]530
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]531\fI\fB
532
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]533\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]534
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]535\fI\fB
536
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]537\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]538
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]539\fI\fB
540
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]541\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]542
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]543\fI\fB
544
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]545\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
546
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]547\fI\fB
548
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]549\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]550
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]551\fI\fB
552
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]553\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]554
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]555\fI\fB
556
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]557\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]558
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]559\fI\fB
560
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]561\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]562
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]563\fI\fB
564
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]565\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]566
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]567\fI\fB
568
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]569\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]570
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]571\fI\fB
572
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]573\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]574
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]575\fI\fB
576
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]577\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]578
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]579\fI\fB
580
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]581\fBvoid png_set_palette_to_rgb(png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]582
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]583\fI\fB
584
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]585\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]586
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]587\fI\fB
588
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]589\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]590
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]591\fI\fB
592
Glenn Randers-Pehrson1916f6a2008-08-14 13:44:49 -0500[diff] [blame]593\fBvoid png_set_premultiply_alpha (png_structp \fIpng_ptr\fP\fB);\fP
594
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]595\fI\fB
596
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]597\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]598
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]599\fI\fB
600
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]601\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]602
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]603\fI\fB
604
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]605\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]606
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]607\fI\fB
608
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]609\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]610
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]611\fI\fB
612
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]613\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]614
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]615\fI\fB
616
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]617\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
618
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]619\fI\fB
620
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]621\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]622
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]623\fI\fB
624
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]625\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
626
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]627\fI\fB
628
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]629\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]630
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]631\fI\fB
632
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]633\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
634
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]635\fI\fB
636
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]637\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]638
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]639\fI\fB
640
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]641\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]642
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]643\fI\fB
644
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]645\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]646
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]647\fI\fB
648
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]649\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]650
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]651\fI\fB
652
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]653\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]654
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]655\fI\fB
656
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]657\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]658
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]659\fI\fB
660
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]661\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]662
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]663\fI\fB
664
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]665\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]666
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]667\fI\fB
668
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]669\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]670
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]671\fI\fB
672
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]673\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]674
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]675\fI\fB
676
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]677\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]678
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]679\fI\fB
680
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]681\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]682
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]683\fI\fB
684
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]685\fBvoid png_set_tRNS_to_alpha(png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]686
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]687\fI\fB
688
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]689\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
690
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]691\fI\fB
692
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]693\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
694
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]695\fI\fB
696
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]697\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]698
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]699\fI\fB
700
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]701\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
702
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]703\fI\fB
704
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]705\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]706
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]707\fI\fB
708
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]709\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]710
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]711\fI\fB
712
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]713\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]714
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]715\fI\fB
716
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]717\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]718
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]719\fI\fB
720
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]721\fBvoid png_set_compression_buffer_size(png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
722
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]723\fI\fB
724
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]725\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]726
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]727\fI\fB
728
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]729\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]730
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]731\fI\fB
732
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]733\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]734
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]735\fI\fB
736
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]737\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]738
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]739\fI\fB
740
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]741\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]742
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]743\fI\fB
744
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]745\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]746
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]747\fI\fB
748
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]749\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]750
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]751\fI\fB
752
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]753\fBvoid png_write_destroy (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]754
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]755\fI\fB
756
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]757\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]758
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]759\fI\fB
760
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]761\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]762
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]763\fI\fB
764
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]765\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]766
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]767\fI\fB
768
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]769\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]770
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]771\fI\fB
772
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]773\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
774
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]775\fI\fB
776
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]777\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]778
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]779\fI\fB
780
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]781\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]782
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]783\fI\fB
784
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]785\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]786
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]787\fI\fB
788
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]789\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
790
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]791\fI\fB
792
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]793\fBvoidpf png_zalloc (voidpf \fP\fIpng_ptr\fP\fB, uInt \fP\fIitems\fP\fB, uInt \fIsize\fP\fB);\fP
794
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]795\fI\fB
796
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]797\fBvoid png_zfree (voidpf \fP\fIpng_ptr\fP\fB, voidpf \fIptr\fP\fB);\fP
798
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]799\fI\fB
800
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]801.SH DESCRIPTION
802The
803.I libpng
804library supports encoding, decoding, and various manipulations of
805the Portable Network Graphics (PNG) format image files. It uses the
806.IR zlib(3)
807compression library.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]808Following is a copy of the libpng.txt file that accompanies libpng.
809.SH LIBPNG.TXT
810libpng.txt - A description on how to use and modify libpng
811
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]812 libpng version 1.4.0beta63 - June 8, 2009
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]813 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]814 <glennrp at users.sourceforge.net>
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]815 Copyright (c) 1998-2009 Glenn Randers-Pehrson
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]816 For conditions of distribution and use, see copyright
817 notice in png.h.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]818
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]819 Based on:
820
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]821 libpng versions 0.97, January 1998, through 1.4.0beta63 - June 8, 2009
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]822 Updated and distributed by Glenn Randers-Pehrson
Glenn Randers-Pehrsona93c9422009-04-13 11:41:33 -0500[diff] [blame]823 Copyright (c) 1998-2009 Glenn Randers-Pehrson
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]824
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]825 libpng 1.0 beta 6 version 0.96 May 28, 1997
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]826 Updated and distributed by Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]827 Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]828
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]829 libpng 1.0 beta 2 - version 0.88 January 26, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]830 For conditions of distribution and use, see copyright
831 notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]832 Schalnat, Group 42, Inc.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]833
834 Updated/rewritten per request in the libpng FAQ
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]835 Copyright (c) 1995, 1996 Frank J. T. Wojcik
836 December 18, 1995 & January 20, 1996
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]837
838.SH I. Introduction
839
840This file describes how to use and modify the PNG reference library
841(known as libpng) for your own use. There are five sections to this
842file: introduction, structures, reading, writing, and modification and
843configuration notes for various special platforms. In addition to this
844file, example.c is a good starting point for using the library, as
845it is heavily commented and should include everything most people
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]846will need. We assume that libpng is already installed; see the
847INSTALL file for instructions on how to install libpng.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]848
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]849For examples of libpng usage, see the files "example.c", "pngtest.c",
850and the files in the "contrib" directory, all of which are included in the
851libpng distribution.
852
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]853Libpng was written as a companion to the PNG specification, as a way
854of reducing the amount of time and effort it takes to support the PNG
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]855file format in application programs.
856
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]857The PNG specification (second edition), November 2003, is available as
858a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2003 (E)) at
859<http://www.w3.org/TR/2003/REC-PNG-20031110/
860The W3C and ISO documents have identical technical content.
861
862The PNG-1.2 specification is available at
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]863<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
864to the PNG specification (second edition) but has some additional material.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]865
866The PNG-1.0 specification is available
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]867as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]868W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
869
870Some additional chunks are described in the special-purpose public chunks
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]871documents at <http://www.libpng.org/pub/png/documents/>.
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]872
873Other information
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]874about 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]875page, <http://www.libpng.org/pub/png/>.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]876
877Most users will not have to modify the library significantly; advanced
878users may want to modify it more. All attempts were made to make it as
879complete as possible, while keeping the code easy to understand.
880Currently, this library only supports C. Support for other languages
881is being considered.
882
883Libpng has been designed to handle multiple sessions at one time,
884to be easily modifiable, to be portable to the vast majority of
885machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
886to use. The ultimate goal of libpng is to promote the acceptance of
887the PNG file format in whatever way possible. While there is still
888work to be done (see the TODO file), libpng should cover the
889majority of the needs of its users.
890
891Libpng uses zlib for its compression and decompression of PNG files.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]892Further information about zlib, and the latest version of zlib, can
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]893be 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]894The zlib compression utility is a general purpose utility that is
895useful for more than PNG files, and can be used without libpng.
896See the documentation delivered with zlib for more details.
897You can usually find the source files for the zlib utility wherever you
898find the libpng source files.
899
900Libpng is thread safe, provided the threads are using different
901instances of the structures. Each thread should have its own
902png_struct and png_info instances, and thus its own image.
903Libpng does not protect itself against two threads using the
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]904same instance of a structure.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]905
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]906.SH II. Structures
907
908There are two main structures that are important to libpng, png_struct
909and png_info. The first, png_struct, is an internal structure that
910will 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]911variable passed to every libpng function call.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]912
913The png_info structure is designed to provide information about the
914PNG file. At one time, the fields of png_info were intended to be
915directly accessible to the user. However, this tended to cause problems
916with applications using dynamically loaded libraries, and as a result
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]917a set of interface functions for png_info (the png_get_*() and png_set_*()
918functions) was developed. The fields of png_info are still available for
919older applications, but it is suggested that applications use the new
920interfaces if at all possible.
921
922Applications that do make direct access to the members of png_struct (except
923for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
924and applications that make direct access to the members of png_info must
925be recompiled if they were compiled or loaded with libpng version 1.0.6,
926in which the members were in a different order. In version 1.0.7, the
927members of the png_info structure reverted to the old order, as they were
928in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
929structures are going to be hidden, and the contents of the structures will
930only be accessible through the png_get/png_set functions.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]931
932The png.h header file is an invaluable reference for programming with libpng.
933And while I'm on the topic, make sure you include the libpng header file:
934
935#include <png.h>
936
937.SH III. Reading
938
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]939We'll now walk you through the possible functions to call when reading
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]940in a PNG file sequentially, briefly explaining the syntax and purpose
941of each one. See example.c and png.h for more detail. While
942progressive reading is covered in the next section, you will still
943need some of the functions discussed in this section to read a PNG
944file.
945
946.SS Setup
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]947
948You will want to do the I/O initialization(*) before you get into libpng,
949so if it doesn't work, you don't have much to undo. Of course, you
950will also want to insure that you are, in fact, dealing with a PNG
951file. 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]952To 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]953png_sig_cmp(), and it will return 0 (false) if the bytes match the
954corresponding bytes of the PNG signature, or nonzero (true) otherwise.
955Of course, the more bytes you pass in, the greater the accuracy of the
956prediction.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]957
958If you are intending to keep the file pointer open for use in libpng,
959you must ensure you don't read more than 8 bytes from the beginning
960of the file, and you also have to make a call to png_set_sig_bytes_read()
961with the number of bytes you read from the beginning. Libpng will
962then only check the bytes (if any) that your program didn't read.
963
964(*): If you are not using the standard I/O functions, you will need
965to replace them with custom functions. See the discussion under
966Customizing libpng.
967
968
969 FILE *fp = fopen(file_name, "rb");
970 if (!fp)
971 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]972 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]973 }
974 fread(header, 1, number, fp);
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]975 is_png = !png_sig_cmp(header, 0, number);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]976 if (!is_png)
977 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]978 return (NOT_PNG);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]979 }
980
981
982Next, png_struct and png_info need to be allocated and initialized. In
983order to ensure that the size of these structures is correct even with a
984dynamically linked libpng, there are functions to initialize and
985allocate the structures. We also pass the library version, optional
986pointers to error handling functions, and a pointer to a data struct for
987use by the error functions, if necessary (the pointer and functions can
988be NULL if the default error handlers are to be used). See the section
989on Changes to Libpng below regarding the old initialization functions.
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]990The structure allocation functions quietly return NULL if they fail to
991create the structure, so your application should check for that.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]992
993 png_structp png_ptr = png_create_read_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]994 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]995 user_error_fn, user_warning_fn);
996 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]997 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]998
999 png_infop info_ptr = png_create_info_struct(png_ptr);
1000 if (!info_ptr)
1001 {
1002 png_destroy_read_struct(&png_ptr,
1003 (png_infopp)NULL, (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]1004 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1005 }
1006
1007 png_infop end_info = png_create_info_struct(png_ptr);
1008 if (!end_info)
1009 {
1010 png_destroy_read_struct(&png_ptr, &info_ptr,
1011 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]1012 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1013 }
1014
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1015If you want to use your own memory allocation routines,
1016define PNG_USER_MEM_SUPPORTED and use
1017png_create_read_struct_2() instead of png_create_read_struct():
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1018
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]1019 png_structp png_ptr = png_create_read_struct_2
1020 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
1021 user_error_fn, user_warning_fn, (png_voidp)
1022 user_mem_ptr, user_malloc_fn, user_free_fn);
1023
1024The error handling routines passed to png_create_read_struct()
1025and the memory alloc/free routines passed to png_create_struct_2()
1026are only necessary if you are not using the libpng supplied error
1027handling and memory alloc/free functions.
1028
1029When libpng encounters an error, it expects to longjmp back
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1030to your routine. Therefore, you will need to call setjmp and pass
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1031your png_jmpbuf(png_ptr). If you read the file from different
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1032routines, you will need to update the jmpbuf field every time you enter
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1033a new routine that will call a png_*() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1034
1035See your documentation of setjmp/longjmp for your compiler for more
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1036information on setjmp/longjmp. See the discussion on libpng error
1037handling in the Customizing Libpng section below for more information
1038on the libpng error handling. If an error occurs, and libpng longjmp's
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1039back to your setjmp, you will want to call png_destroy_read_struct() to
1040free any memory.
1041
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1042 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1043 {
1044 png_destroy_read_struct(&png_ptr, &info_ptr,
1045 &end_info);
1046 fclose(fp);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]1047 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1048 }
1049
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1050If you would rather avoid the complexity of setjmp/longjmp issues,
1051you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
1052errors will result in a call to PNG_ABORT() which defaults to abort().
1053
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1054Now you need to set up the input code. The default for libpng is to
1055use the C function fread(). If you use this, you will need to pass a
1056valid FILE * in the function png_init_io(). Be sure that the file is
1057opened in binary mode. If you wish to handle reading data in another
1058way, you need not call the png_init_io() function, but you must then
1059implement the libpng I/O methods discussed in the Customizing Libpng
1060section below.
1061
1062 png_init_io(png_ptr, fp);
1063
1064If you had previously opened the file and read any of the signature from
1065the beginning in order to see if this was a PNG file, you need to let
1066libpng know that there are some bytes missing from the start of the file.
1067
1068 png_set_sig_bytes(png_ptr, number);
1069
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1070.SS Setting up callback code
1071
1072You can set up a callback function to handle any unknown chunks in the
1073input stream. You must supply the function
1074
1075 read_chunk_callback(png_ptr ptr,
1076 png_unknown_chunkp chunk);
1077 {
1078 /* The unknown chunk structure contains your
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1079 chunk data, along with similar data for any other
1080 unknown chunks: */
1081
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1082 png_byte name[5];
1083 png_byte *data;
1084 png_size_t size;
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1085
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1086 /* Note that libpng has already taken care of
1087 the CRC handling */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1088
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1089 /* put your code here. Search for your chunk in the
1090 unknown chunk structure, process it, and return one
1091 of the following: */
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1092
1093 return (-n); /* chunk had an error */
1094 return (0); /* did not recognize */
1095 return (n); /* success */
1096 }
1097
1098(You can give your function another name that you like instead of
1099"read_chunk_callback")
1100
1101To inform libpng about your function, use
1102
1103 png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
1104 read_chunk_callback);
1105
1106This names not only the callback function, but also a user pointer that
1107you can retrieve with
1108
1109 png_get_user_chunk_ptr(png_ptr);
1110
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1111If you call the png_set_read_user_chunk_fn() function, then all unknown
1112chunks will be saved when read, in case your callback function will need
1113one or more of them. This behavior can be changed with the
1114png_set_keep_unknown_chunks() function, described below.
1115
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1116At this point, you can set up a callback function that will be
1117called after each row has been read, which you can use to control
1118a progress meter or the like. It's demonstrated in pngtest.c.
1119You must supply a function
1120
Glenn Randers-Pehrsone68f5a32001-05-14 09:20:53 -0500[diff] [blame]1121 void read_row_callback(png_ptr ptr, png_uint_32 row,
1122 int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]1123 {
1124 /* put your code here */
1125 }
1126
1127(You can give it another name that you like instead of "read_row_callback")
1128
1129To inform libpng about your function, use
1130
1131 png_set_read_status_fn(png_ptr, read_row_callback);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1132
1133.SS Width and height limits
1134
1135The PNG specification allows the width and height of an image to be as
1136large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
1137Since very few applications really need to process such large images,
1138we have imposed an arbitrary 1-million limit on rows and columns.
1139Larger images will be rejected immediately with a png_error() call. If
1140you wish to override this limit, you can use
1141
1142 png_set_user_limits(png_ptr, width_max, height_max);
1143
1144to set your own limits, or use width_max = height_max = 0x7fffffffL
1145to allow all valid dimensions (libpng may reject some very large images
1146anyway because of potential buffer overflow conditions).
1147
1148You should put this statement after you create the PNG structure and
1149before calling png_read_info(), png_read_png(), or png_process_data().
1150If you need to retrieve the limits that are being applied, use
1151
1152 width_max = png_get_user_width_max(png_ptr);
1153 height_max = png_get_user_height_max(png_ptr);
1154
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1155.SS Unknown-chunk handling
1156
1157Now you get to set the way the library processes unknown chunks in the
1158input PNG stream. Both known and unknown chunks will be read. Normal
1159behavior is that known chunks will be parsed into information in
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1160various info_ptr members while unknown chunks will be discarded. This
1161behavior can be wasteful if your application will never use some known
1162chunk types. To change this, you can call:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1163
Glenn Randers-Pehrson272489d2004-08-04 06:34:52 -0500[diff] [blame]1164 png_set_keep_unknown_chunks(png_ptr, keep,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1165 chunk_list, num_chunks);
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1166 keep - 0: default unknown chunk handling
1167 1: ignore; do not keep
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1168 2: keep only if safe-to-copy
1169 3: keep even if unsafe-to-copy
1170 You can use these definitions:
1171 PNG_HANDLE_CHUNK_AS_DEFAULT 0
1172 PNG_HANDLE_CHUNK_NEVER 1
1173 PNG_HANDLE_CHUNK_IF_SAFE 2
1174 PNG_HANDLE_CHUNK_ALWAYS 3
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1175 chunk_list - list of chunks affected (a byte string,
1176 five bytes per chunk, NULL or '\0' if
1177 num_chunks is 0)
1178 num_chunks - number of chunks affected; if 0, all
Glenn Randers-Pehrsondff799e2004-08-07 21:42:49 -0500[diff] [blame]1179 unknown chunks are affected. If nonzero,
1180 only the chunks in the list are affected
1181
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1182Unknown chunks declared in this way will be saved as raw data onto a
1183list of png_unknown_chunk structures. If a chunk that is normally
1184known to libpng is named in the list, it will be handled as unknown,
1185according to the "keep" directive. If a chunk is named in successive
1186instances of png_set_keep_unknown_chunks(), the final instance will
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]1187take precedence. The IHDR and IEND chunks should not be named in
1188chunk_list; if they are, libpng will process them normally anyway.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1189
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1190Here is an example of the usage of png_set_keep_unknown_chunks(),
1191where the private "vpAg" chunk will later be processed by a user chunk
1192callback function:
1193
1194 png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
1195
1196 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1197 png_byte unused_chunks[]=
1198 {
1199 104, 73, 83, 84, (png_byte) '\0', /* hIST */
1200 105, 84, 88, 116, (png_byte) '\0', /* iTXt */
1201 112, 67, 65, 76, (png_byte) '\0', /* pCAL */
1202 115, 67, 65, 76, (png_byte) '\0', /* sCAL */
1203 115, 80, 76, 84, (png_byte) '\0', /* sPLT */
1204 116, 73, 77, 69, (png_byte) '\0', /* tIME */
1205 };
1206 #endif
1207
1208 ...
1209
1210 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
1211 /* ignore all unknown chunks: */
1212 png_set_keep_unknown_chunks(read_ptr, 1, NULL, 0);
1213 /* except for vpAg: */
1214 png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
1215 /* also ignore unused known chunks: */
1216 png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
1217 (int)sizeof(unused_chunks)/5);
1218 #endif
1219
Glenn Randers-Pehrson800d1e92008-08-20 17:25:21 -0500[diff] [blame]1220.SS User limits
1221
1222The PNG specification allows the width and height of an image to be as
1223large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
1224Since very few applications really need to process such large images,
1225we have imposed an arbitrary 1-million limit on rows and columns.
1226Larger images will be rejected immediately with a png_error() call. If
1227you wish to override this limit, you can use
1228
1229 png_set_user_limits(png_ptr, width_max, height_max);
1230
1231to set your own limits, or use width_max = height_max = 0x7fffffffL
1232to allow all valid dimensions (libpng may reject some very large images
1233anyway because of potential buffer overflow conditions).
1234
1235You should put this statement after you create the PNG structure and
1236before calling png_read_info(), png_read_png(), or png_process_data().
1237If you need to retrieve the limits that are being applied, use
1238
1239 width_max = png_get_user_width_max(png_ptr);
1240 height_max = png_get_user_height_max(png_ptr);
1241
1242The PNG specification sets no limit on the number of ancillary chunks
1243allowed in a PNG datastream. You can impose a limit on the total number
1244of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
1245
1246 png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
1247
1248where 0x7fffffffL means unlimited. You can retrieve this limit with
1249
1250 chunk_cache_max = png_get_chunk_cache_max(png_ptr);
1251
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1252.SS The high-level read interface
1253
1254At this point there are two ways to proceed; through the high-level
1255read interface, or through a sequence of low-level read operations.
1256You can use the high-level interface if (a) you are willing to read
1257the entire image into memory, and (b) the input transformations
1258you want to do are limited to the following set:
1259
1260 PNG_TRANSFORM_IDENTITY No transformation
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1261 PNG_TRANSFORM_STRIP_16 Strip 16-bit samples to
1262 8 bits
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1263 PNG_TRANSFORM_STRIP_ALPHA Discard the alpha channel
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1264 PNG_TRANSFORM_PACKING Expand 1, 2 and 4-bit
1265 samples to bytes
1266 PNG_TRANSFORM_PACKSWAP Change order of packed
1267 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1268 PNG_TRANSFORM_EXPAND Perform set_expand()
1269 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1270 PNG_TRANSFORM_SHIFT Normalize pixels to the
1271 sBIT depth
1272 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
1273 to BGRA
1274 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
1275 to AG
1276 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
1277 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1278 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
1279
1280(This excludes setting a background color, doing gamma transformation,
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1281dithering, and setting filler.) If this is the case, simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1282
1283 png_read_png(png_ptr, info_ptr, png_transforms, NULL)
1284
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]1285where png_transforms is an integer containing the bitwise OR of
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1286some set of transformation flags. This call is equivalent to png_read_info(),
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1287followed the set of transformations indicated by the transform mask,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1288then png_read_image(), and finally png_read_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1289
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1290(The final parameter of this call is not yet used. Someday it might point
1291to transformation parameters required by some future input transform.)
1292
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]1293You must use png_transforms and not call any png_set_transform() functions
1294when you use png_read_png().
1295
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1296After you have called png_read_png(), you can retrieve the image data
1297with
1298
1299 row_pointers = png_get_rows(png_ptr, info_ptr);
1300
1301where row_pointers is an array of pointers to the pixel data for each row:
1302
1303 png_bytep row_pointers[height];
1304
1305If you know your image size and pixel size ahead of time, you can allocate
1306row_pointers prior to calling png_read_png() with
1307
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1308 if (height > PNG_UINT_32_MAX/png_sizeof(png_byte))
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]1309 png_error (png_ptr,
1310 "Image is too tall to process in memory");
1311 if (width > PNG_UINT_32_MAX/pixel_size)
1312 png_error (png_ptr,
1313 "Image is too wide to process in memory");
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1314 row_pointers = png_malloc(png_ptr,
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1315 height*png_sizeof(png_bytep));
1316 for (int i=0; i<height, i++)
1317 row_pointers[i]=NULL; /* security precaution */
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1318 for (int i=0; i<height, i++)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1319 row_pointers[i]=png_malloc(png_ptr,
1320 width*pixel_size);
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]1321 png_set_rows(png_ptr, info_ptr, &row_pointers);
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]1322
1323Alternatively you could allocate your image in one big block and define
1324row_pointers[i] to point into the proper places in your block.
1325
1326If you use png_set_rows(), the application is responsible for freeing
1327row_pointers (and row_pointers[i], if they were separately allocated).
1328
1329If you don't allocate row_pointers ahead of time, png_read_png() will
1330do it, and it'll be free'ed when you call png_destroy_*().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1331
1332.SS The low-level read interface
1333
1334If you are going the low-level route, you are now ready to read all
1335the file information up to the actual image data. You do this with a
1336call to png_read_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1337
1338 png_read_info(png_ptr, info_ptr);
1339
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1340This will process all chunks up to but not including the image data.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1341
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1342.SS Querying the info structure
1343
1344Functions are used to get the information from the info_ptr once it
1345has been read. Note that these fields may not be completely filled
1346in until png_read_end() has read the chunk data following the image.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1347
1348 png_get_IHDR(png_ptr, info_ptr, &width, &height,
1349 &bit_depth, &color_type, &interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1350 &compression_type, &filter_method);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1351
1352 width - holds the width of the image
1353 in pixels (up to 2^31).
1354 height - holds the height of the image
1355 in pixels (up to 2^31).
1356 bit_depth - holds the bit depth of one of the
1357 image channels. (valid values are
1358 1, 2, 4, 8, 16 and depend also on
1359 the color_type. See also
1360 significant bits (sBIT) below).
1361 color_type - describes which color/alpha channels
1362 are present.
1363 PNG_COLOR_TYPE_GRAY
1364 (bit depths 1, 2, 4, 8, 16)
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1365 PNG_COLOR_TYPE_GRAY_ALPHA
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1366 (bit depths 8, 16)
1367 PNG_COLOR_TYPE_PALETTE
1368 (bit depths 1, 2, 4, 8)
1369 PNG_COLOR_TYPE_RGB
1370 (bit_depths 8, 16)
1371 PNG_COLOR_TYPE_RGB_ALPHA
1372 (bit_depths 8, 16)
1373
1374 PNG_COLOR_MASK_PALETTE
1375 PNG_COLOR_MASK_COLOR
1376 PNG_COLOR_MASK_ALPHA
1377
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1378 filter_method - (must be PNG_FILTER_TYPE_BASE
1379 for PNG 1.0, and can also be
1380 PNG_INTRAPIXEL_DIFFERENCING if
1381 the PNG datastream is embedded in
1382 a MNG-1.0 datastream)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1383 compression_type - (must be PNG_COMPRESSION_TYPE_BASE
1384 for PNG 1.0)
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1385 interlace_type - (PNG_INTERLACE_NONE or
1386 PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1387 Any or all of interlace_type, compression_type, of
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1388 filter_method can be NULL if you are
1389 not interested in their values.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1390
1391 channels = png_get_channels(png_ptr, info_ptr);
1392 channels - number of channels of info for the
1393 color type (valid values are 1 (GRAY,
1394 PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
1395 4 (RGB_ALPHA or RGB + filler byte))
1396 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
1397 rowbytes - number of bytes needed to hold a row
1398
1399 signature = png_get_signature(png_ptr, info_ptr);
1400 signature - holds the signature read from the
1401 file (if any). The data is kept in
1402 the same offset it would be if the
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1403 whole signature were read (i.e. if an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1404 application had already read in 4
1405 bytes of signature before starting
1406 libpng, the remaining 4 bytes would
1407 be in signature[4] through signature[7]
1408 (see png_set_sig_bytes())).
1409
1410
1411 width = png_get_image_width(png_ptr,
1412 info_ptr);
1413 height = png_get_image_height(png_ptr,
1414 info_ptr);
1415 bit_depth = png_get_bit_depth(png_ptr,
1416 info_ptr);
1417 color_type = png_get_color_type(png_ptr,
1418 info_ptr);
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]1419 filter_method = png_get_filter_type(png_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1420 info_ptr);
1421 compression_type = png_get_compression_type(png_ptr,
1422 info_ptr);
1423 interlace_type = png_get_interlace_type(png_ptr,
1424 info_ptr);
1425
1426
1427These are also important, but their validity depends on whether the chunk
1428has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
1429png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
1430data has been read, or zero if it is missing. The parameters to the
1431png_get_<chunk> are set directly if they are simple data types, or a pointer
1432into the info_ptr is returned for any complex types.
1433
1434 png_get_PLTE(png_ptr, info_ptr, &palette,
1435 &num_palette);
1436 palette - the palette for the file
1437 (array of png_color)
1438 num_palette - number of entries in the palette
1439
1440 png_get_gAMA(png_ptr, info_ptr, &gamma);
1441 gamma - the gamma the file is written
1442 at (PNG_INFO_gAMA)
1443
1444 png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
1445 srgb_intent - the rendering intent (PNG_INFO_sRGB)
1446 The presence of the sRGB chunk
1447 means that the pixel data is in the
1448 sRGB color space. This chunk also
1449 implies specific values of gAMA and
1450 cHRM.
1451
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1452 png_get_iCCP(png_ptr, info_ptr, &name,
1453 &compression_type, &profile, &proflen);
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1454 name - The profile name.
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]1455 compression - The compression type; always
1456 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
1457 You may give NULL to this argument to
1458 ignore it.
1459 profile - International Color Consortium color
1460 profile data. May contain NULs.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]1461 proflen - length of profile data in bytes.
1462
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1463 png_get_sBIT(png_ptr, info_ptr, &sig_bit);
1464 sig_bit - the number of significant bits for
1465 (PNG_INFO_sBIT) each of the gray,
1466 red, green, and blue channels,
1467 whichever are appropriate for the
1468 given color type (png_color_16)
1469
1470 png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1471 &trans_color);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1472 trans - array of transparent entries for
1473 palette (PNG_INFO_tRNS)
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]1474 trans_color - graylevel or color sample values of
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]1475 the single transparent color for
1476 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1477 num_trans - number of transparent entries
1478 (PNG_INFO_tRNS)
1479
1480 png_get_hIST(png_ptr, info_ptr, &hist);
1481 (PNG_INFO_hIST)
1482 hist - histogram of palette (array of
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1483 png_uint_16)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1484
1485 png_get_tIME(png_ptr, info_ptr, &mod_time);
1486 mod_time - time image was last modified
1487 (PNG_VALID_tIME)
1488
1489 png_get_bKGD(png_ptr, info_ptr, &background);
1490 background - background color (PNG_VALID_bKGD)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1491 valid 16-bit red, green and blue
1492 values, regardless of color_type
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1493
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]1494 num_comments = png_get_text(png_ptr, info_ptr,
1495 &text_ptr, &num_text);
1496 num_comments - number of comments
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1497 text_ptr - array of png_text holding image
1498 comments
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1499 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1500 on "text" PNG_TEXT_COMPRESSION_NONE
1501 PNG_TEXT_COMPRESSION_zTXt
1502 PNG_ITXT_COMPRESSION_NONE
1503 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1504 text_ptr[i].key - keyword for comment. Must contain
1505 1-79 characters.
1506 text_ptr[i].text - text comments for current
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]1507 keyword. Can be empty.
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1508 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1509 after decompression, 0 for iTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1510 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]1511 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1512 text_ptr[i].lang - language of comment (empty
1513 string for unknown).
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]1514 text_ptr[i].lang_key - keyword in UTF-8
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]1515 (empty string for unknown).
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()
1663is called to insert filler bytes, either before or after each RGB triplet.
166416-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
1665byte of the color value first, unless png_set_strip_16() is called to
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]1666transform it to regular RGB RGB triplets, or png_set_filler() or
1667png_set_add alpha() is called to insert filler bytes, either before or
1668after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
1669be modified with
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1670png_set_filler(), png_set_add_alpha(), or png_set_strip_16().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1671
1672The following code transforms grayscale images of less than 8 to 8 bits,
1673changes paletted images to RGB, and adds a full alpha channel if there is
1674transparency information in a tRNS chunk. This is most useful on
1675grayscale images with bit depths of 2 or 4 or if there is a multiple-image
1676viewing application that wishes to treat all images in the same way.
1677
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]1678 if (color_type == PNG_COLOR_TYPE_PALETTE)
1679 png_set_palette_to_rgb(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1680
1681 if (color_type == PNG_COLOR_TYPE_GRAY &&
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]1682 bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1683
1684 if (png_get_valid(png_ptr, info_ptr,
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]1685 PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
1686
1687These three functions are actually aliases for png_set_expand(), added
1688in libpng version 1.0.4, with the function names expanded to improve code
1689readability. In some future version they may actually do different
1690things.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1691
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]1692As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
1693added. It expands the sample depth without changing tRNS to alpha.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1694
Glenn Randers-Pehrson7aa18342009-06-05 17:24:17 -0500[diff] [blame]1695As of libpng version 1.4.0beta63, not all possible expansions are supported.
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]1696
1697In the following table, the 01 means grayscale with depth<8, 31 means
1698indexed with depth<8, other numerals represent the color type, "T" means
1699the tRNS chunk is present, A means an alpha channel is present, and O
1700means tRNS or alpha is present but all pixels in the image are opaque.
1701
1702 FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
1703 TO
1704 01 -
1705 31 -
1706 0 1 -
1707 0T -
1708 0O -
1709 2 GX -
1710 2T -
1711 2O -
1712 3 1 -
1713 3T -
1714 3O -
1715 4A T -
1716 4O -
1717 6A GX TX TX -
1718 6O GX TX -
1719
1720Within the matrix,
1721 "-" means the transformation is not supported.
1722 "X" means the transformation is obtained by png_set_expand().
1723 "1" means the transformation is obtained by
1724 png_set_expand_gray_1_2_4_to_8
1725 "G" means the transformation is obtained by
1726 png_set_gray_to_rgb().
1727 "P" means the transformation is obtained by
1728 png_set_expand_palette_to_rgb().
1729 "T" means the transformation is obtained by
1730 png_set_tRNS_to_alpha().
Glenn Randers-Pehrson1ce08362006-03-08 23:35:59 -0600[diff] [blame]1731
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1732PNG can have files with 16 bits per channel. If you only can handle
17338 bits per channel, this will strip the pixels down to 8 bit.
1734
1735 if (bit_depth == 16)
1736 png_set_strip_16(png_ptr);
1737
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1738If, for some reason, you don't need the alpha channel on an image,
1739and you want to remove it rather than combining it with the background
1740(but the image author certainly had in mind that you *would* combine
1741it with the background, so that's what you should probably do):
1742
1743 if (color_type & PNG_COLOR_MASK_ALPHA)
1744 png_set_strip_alpha(png_ptr);
1745
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1746In PNG files, the alpha channel in an image
1747is the level of opacity. If you need the alpha channel in an image to
1748be the level of transparency instead of opacity, you can invert the
1749alpha channel (or the tRNS chunk data) after it's read, so that 0 is
1750fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
1751images) is fully transparent, with
1752
1753 png_set_invert_alpha(png_ptr);
1754
Glenn Randers-Pehrson1916f6a2008-08-14 13:44:49 -0500[diff] [blame]1755The PNG format only supports pixels with postmultiplied alpha.
1756If you want to replace the pixels, after reading them, with pixels
1757that have premultiplied color samples, you can do this with
1758
1759 png_set_premultiply_alpha(png_ptr);
1760
Glenn Randers-Pehrson41983602008-08-18 21:52:21 -0500[diff] [blame]1761If you do this, any input with a tRNS chunk will be expanded to
1762have an alpha channel.
1763
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1764PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
1765they can, resulting in, for example, 8 pixels per byte for 1 bit
1766files. This code expands to 1 pixel per byte without changing the
1767values of the pixels:
1768
1769 if (bit_depth < 8)
1770 png_set_packing(png_ptr);
1771
1772PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
1773stored in a PNG image have been "scaled" or "shifted" up to the next
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1774higher possible bit depth (e.g. from 5 bits/sample in the range [0,31] to
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]17758 bits/sample in the range [0, 255]). However, it is also possible to
1776convert the PNG pixel data back to the original bit depth of the image.
1777This call reduces the pixels back down to the original bit depth:
1778
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]1779 png_color_8p sig_bit;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1780
1781 if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
1782 png_set_shift(png_ptr, sig_bit);
1783
1784PNG files store 3-color pixels in red, green, blue order. This code
1785changes the storage of the pixels to blue, green, red:
1786
1787 if (color_type == PNG_COLOR_TYPE_RGB ||
1788 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
1789 png_set_bgr(png_ptr);
1790
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]1791PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
1792into 4 or 8 bytes for windowing systems that need them in this format:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1793
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]1794 if (color_type == PNG_COLOR_TYPE_RGB)
1795 png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1796
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]1797where "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]1798either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
1799you want the filler before the RGB or after. This transformation
Glenn Randers-Pehrson1b8e5672001-08-25 06:46:06 -0500[diff] [blame]1800does not affect images that already have full alpha channels. To add an
1801opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
1802will generate RGBA pixels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1803
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1804Note that png_set_filler() does not change the color type. If you want
1805to do that, you can add a true alpha channel with
1806
1807 if (color_type == PNG_COLOR_TYPE_RGB ||
1808 color_type == PNG_COLOR_TYPE_GRAY)
1809 png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
1810
1811where "filler" contains the alpha value to assign to each pixel.
Glenn Randers-Pehrson16e11662004-11-01 14:13:40 -0600[diff] [blame]1812This function was added in libpng-1.2.7.
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]1813
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1814If you are reading an image with an alpha channel, and you need the
1815data as ARGB instead of the normal PNG format RGBA:
1816
1817 if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
1818 png_set_swap_alpha(png_ptr);
1819
1820For some uses, you may want a grayscale image to be represented as
1821RGB. This code will do that conversion:
1822
1823 if (color_type == PNG_COLOR_TYPE_GRAY ||
1824 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
1825 png_set_gray_to_rgb(png_ptr);
1826
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1827Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1828with alpha.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1829
1830 if (color_type == PNG_COLOR_TYPE_RGB ||
1831 color_type == PNG_COLOR_TYPE_RGB_ALPHA)
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1832 png_set_rgb_to_gray_fixed(png_ptr, error_action,
1833 int red_weight, int green_weight);
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1834
1835 error_action = 1: silently do the conversion
1836 error_action = 2: issue a warning if the original
1837 image has any pixel where
1838 red != green or red != blue
1839 error_action = 3: issue an error and abort the
1840 conversion if the original
1841 image has any pixel where
1842 red != green or red != blue
1843
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1844 red_weight: weight of red component times 100000
1845 green_weight: weight of green component times 100000
1846 If either weight is negative, default
1847 weights (21268, 71514) are used.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1848
1849If you have set error_action = 1 or 2, you can
1850later check whether the image really was gray, after processing
1851the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
1852It will return a png_byte that is zero if the image was gray or
18531 if there were any non-gray pixels. bKGD and sBIT data
1854will be silently converted to grayscale, using the green channel
1855data, regardless of the error_action setting.
1856
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1857With red_weight+green_weight<=100000,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1858the normalized graylevel is computed:
1859
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1860 int rw = red_weight * 65536;
1861 int gw = green_weight * 65536;
1862 int bw = 65536 - (rw + gw);
1863 gray = (rw*red + gw*green + bw*blue)/65536;
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1864
1865The default values approximate those recommended in the Charles
1866Poynton's Color FAQ, <http://www.inforamp.net/~poynton/>
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]1867Copyright (c) 1998-01-04 Charles Poynton <poynton at inforamp.net>
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1868
1869 Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
1870
1871Libpng approximates this with
1872
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1873 Y = 0.21268 * R + 0.7151 * G + 0.07217 * B
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1874
1875which can be expressed with integers as
1876
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1877 Y = (6969 * R + 23434 * G + 2365 * B)/32768
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1878
1879The calculation is done in a linear colorspace, if the image gamma
1880is known.
1881
Glenn Randers-Pehrson73d57cb2002-03-25 18:49:08 -0600[diff] [blame]1882If you have a grayscale and you are using png_set_expand_depth(),
1883png_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]1884a higher bit-depth, you must either supply the background color as a gray
1885value at the original file bit-depth (need_expand = 1) or else supply the
1886background color as an RGB triplet at the final, expanded bit depth
1887(need_expand = 0). Similarly, if you are reading a paletted image, you
1888must either supply the background color as a palette index (need_expand = 1)
1889or 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]1890
1891 png_color_16 my_background;
1892 png_color_16p image_background;
1893
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]1894 if (png_get_bKGD(png_ptr, info_ptr, &image_background))
1895 png_set_background(png_ptr, image_background,
1896 PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1897 else
1898 png_set_background(png_ptr, &my_background,
1899 PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
1900
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]1901The png_set_background() function tells libpng to composite images
1902with alpha or simple transparency against the supplied background
1903color. If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
1904you may use this color, or supply another color more suitable for
1905the current display (e.g., the background color from a web page). You
1906need to tell libpng whether the color is in the gamma space of the
1907display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
1908(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
1909that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
1910know why anyone would use this, but it's here).
1911
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1912To properly display PNG images on any kind of system, the application needs
1913to know what the display gamma is. Ideally, the user will know this, and
1914the application will allow them to set it. One method of allowing the user
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]1915to set the display gamma separately for each system is to check for a
1916SCREEN_GAMMA or DISPLAY_GAMMA environment variable, which will hopefully be
1917correctly set.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1918
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]1919Note that display_gamma is the overall gamma correction required to produce
1920pleasing results, which depends on the lighting conditions in the surrounding
1921environment. In a dim or brightly lit room, no compensation other than
1922the physical gamma exponent of the monitor is needed, while in a dark room
1923a slightly smaller exponent is better.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1924
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]1925 double gamma, screen_gamma;
1926
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1927 if (/* We have a user-defined screen
1928 gamma value */)
1929 {
1930 screen_gamma = user_defined_screen_gamma;
1931 }
1932 /* One way that applications can share the same
1933 screen gamma value */
1934 else if ((gamma_str = getenv("SCREEN_GAMMA"))
1935 != NULL)
1936 {
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]1937 screen_gamma = (double)atof(gamma_str);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1938 }
1939 /* If we don't have another value */
1940 else
1941 {
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1942 screen_gamma = 2.2; /* A good guess for a
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1943 PC monitor in a bright office or a dim room */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1944 screen_gamma = 2.0; /* A good guess for a
1945 PC monitor in a dark room */
1946 screen_gamma = 1.7 or 1.0; /* A good
1947 guess for Mac systems */
1948 }
1949
1950The png_set_gamma() function handles gamma transformations of the data.
1951Pass both the file gamma and the current screen_gamma. If the file does
1952not 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]1953it 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]1954that file gammas are inverted from screen gammas. See the discussions
1955on gamma in the PNG specification for an excellent description of what
1956gamma is, and why all applications should support it. It is strongly
1957recommended that PNG viewers support gamma correction.
1958
1959 if (png_get_gAMA(png_ptr, info_ptr, &gamma))
1960 png_set_gamma(png_ptr, screen_gamma, gamma);
1961 else
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]1962 png_set_gamma(png_ptr, screen_gamma, 0.45455);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1963
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1964PNG files describe monochrome as black being zero and white being one.
1965The following code will reverse this (make black be one and white be
1966zero):
1967
Glenn Randers-Pehrson1ea0ff32001-08-07 22:25:59 -0500[diff] [blame]1968 if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
1969 png_set_invert_mono(png_ptr);
1970
1971This function can also be used to invert grayscale and gray-alpha images:
1972
1973 if (color_type == PNG_COLOR_TYPE_GRAY ||
1974 color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1975 png_set_invert_mono(png_ptr);
1976
1977PNG files store 16 bit pixels in network byte order (big-endian,
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]1978ie. most significant bits first). This code changes the storage to the
1979other way (little-endian, i.e. least significant bits first, the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]1980way PCs store them):
1981
1982 if (bit_depth == 16)
1983 png_set_swap(png_ptr);
1984
1985If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
1986need to change the order the pixels are packed into bytes, you can use:
1987
1988 if (bit_depth < 8)
1989 png_set_packswap(png_ptr);
1990
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]1991Finally, you can write your own transformation function if none of
1992the existing ones meets your needs. This is done by setting a callback
1993with
1994
1995 png_set_read_user_transform_fn(png_ptr,
1996 read_transform_fn);
1997
1998You must supply the function
1999
2000 void read_transform_fn(png_ptr ptr, row_info_ptr
2001 row_info, png_bytep data)
2002
2003See pngtest.c for a working example. Your function will be called
2004after all of the other transformations have been processed.
2005
2006You can also set up a pointer to a user structure for use by your
2007callback function, and you can inform libpng that your transform
2008function will change the number of channels or bit depth with the
2009function
2010
2011 png_set_user_transform_info(png_ptr, user_ptr,
2012 user_depth, user_channels);
2013
2014The user's application, not libpng, is responsible for allocating and
2015freeing any memory required for the user structure.
2016
2017You can retrieve the pointer via the function
2018png_get_user_transform_ptr(). For example:
2019
2020 voidp read_user_transform_ptr =
2021 png_get_user_transform_ptr(png_ptr);
2022
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2023The last thing to handle is interlacing; this is covered in detail below,
2024but you must call the function here if you want libpng to handle expansion
2025of the interlaced image.
2026
2027 number_of_passes = png_set_interlace_handling(png_ptr);
2028
2029After setting the transformations, libpng can update your png_info
2030structure to reflect any transformations you've requested with this
2031call. This is most useful to update the info structure's rowbytes
2032field so you can use it to allocate your image memory. This function
2033will also update your palette with the correct screen_gamma and
2034background if these have been given with the calls above.
2035
2036 png_read_update_info(png_ptr, info_ptr);
2037
2038After you call png_read_update_info(), you can allocate any
2039memory you need to hold the image. The row data is simply
2040raw byte data for all forms of images. As the actual allocation
2041varies among applications, no example will be given. If you
2042are allocating one large chunk, you will need to build an
2043array of pointers to each row, as it will be needed for some
2044of the functions below.
2045
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2046.SS Reading image data
2047
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2048After you've allocated memory, you can read the image data.
2049The simplest way to do this is in one function call. If you are
2050allocating enough memory to hold the whole image, you can just
2051call png_read_image() and libpng will read in all the image data
2052and put it in the memory area supplied. You will need to pass in
2053an array of pointers to each row.
2054
2055This function automatically handles interlacing, so you don't need
2056to call png_set_interlace_handling() or call this function multiple
2057times, or any of that other stuff necessary with png_read_rows().
2058
2059 png_read_image(png_ptr, row_pointers);
2060
2061where row_pointers is:
2062
2063 png_bytep row_pointers[height];
2064
2065You can point to void or char or whatever you use for pixels.
2066
2067If you don't want to read in the whole image at once, you can
2068use png_read_rows() instead. If there is no interlacing (check
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2069interlace_type == PNG_INTERLACE_NONE), this is simple:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2070
2071 png_read_rows(png_ptr, row_pointers, NULL,
2072 number_of_rows);
2073
2074where row_pointers is the same as in the png_read_image() call.
2075
2076If 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]2077a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2078
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2079 png_bytep row_pointer = row;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2080 png_read_row(png_ptr, row_pointer, NULL);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2081
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2082If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
2083get somewhat harder. The only current (PNG Specification version 1.2)
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2084interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2085is a somewhat complicated 2D interlace scheme, known as Adam7, that
2086breaks down an image into seven smaller images of varying size, based
2087on an 8x8 grid.
2088
2089libpng can fill out those images or it can give them to you "as is".
2090If you want them filled out, there are two ways to do that. The one
2091mentioned in the PNG specification is to expand each pixel to cover
2092those pixels that have not been read yet (the "rectangle" method).
2093This results in a blocky image for the first pass, which gradually
2094smooths out as more pixels are read. The other method is the "sparkle"
2095method, where pixels are drawn only in their final locations, with the
2096rest of the image remaining whatever colors they were initialized to
2097before the start of the read. The first method usually looks better,
2098but tends to be slower, as there are more pixels to put in the rows.
2099
2100If you don't want libpng to handle the interlacing details, just call
2101png_read_rows() seven times to read in all seven images. Each of the
2102images is a valid image by itself, or they can all be combined on an
21038x8 grid to form a single image (although if you intend to combine them
2104you would be far better off using the libpng interlace handling).
2105
2106The first pass will return an image 1/8 as wide as the entire image
2107(every 8th column starting in column 0) and 1/8 as high as the original
2108(every 8th row starting in row 0), the second will be 1/8 as wide
2109(starting in column 4) and 1/8 as high (also starting in row 0). The
2110third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
21111/8 as high (every 8th row starting in row 4), and the fourth pass will
2112be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
2113and every 4th row starting in row 0). The fifth pass will return an
2114image 1/2 as wide, and 1/4 as high (starting at column 0 and row 2),
2115while the sixth pass will be 1/2 as wide and 1/2 as high as the original
2116(starting in column 1 and row 0). The seventh and final pass will be as
2117wide as the original, and 1/2 as high, containing all of the odd
2118numbered scanlines. Phew!
2119
2120If you want libpng to expand the images, call this before calling
2121png_start_read_image() or png_read_update_info():
2122
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2123 if (interlace_type == PNG_INTERLACE_ADAM7)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2124 number_of_passes
2125 = png_set_interlace_handling(png_ptr);
2126
2127This will return the number of passes needed. Currently, this
2128is seven, but may change if another interlace type is added.
2129This function can be called even if the file is not interlaced,
2130where it will return one pass.
2131
2132If you are not going to display the image after each pass, but are
2133going to wait until the entire image is read in, use the sparkle
2134effect. This effect is faster and the end result of either method
2135is exactly the same. If you are planning on displaying the image
2136after each pass, the "rectangle" effect is generally considered the
2137better looking one.
2138
2139If you only want the "sparkle" effect, just call png_read_rows() as
2140normal, with the third parameter NULL. Make sure you make pass over
2141the image number_of_passes times, and you don't change the data in the
2142rows between calls. You can change the locations of the data, just
2143not the data. Each pass only writes the pixels appropriate for that
2144pass, and assumes the data from previous passes is still valid.
2145
2146 png_read_rows(png_ptr, row_pointers, NULL,
2147 number_of_rows);
2148
2149If you only want the first effect (the rectangles), do the same as
2150before except pass the row buffer in the third parameter, and leave
2151the second parameter NULL.
2152
2153 png_read_rows(png_ptr, NULL, row_pointers,
2154 number_of_rows);
2155
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2156.SS Finishing a sequential read
2157
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]2158After you are finished reading the image through the
2159low-level interface, you can finish reading the file. If you are
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2160interested in comments or time, which may be stored either before or
2161after the image data, you should pass the separate png_info struct if
2162you want to keep the comments from before and after the image
2163separate. If you are not interested, you can pass NULL.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2164
2165 png_read_end(png_ptr, end_info);
2166
2167When you are done, you can free all memory allocated by libpng like this:
2168
2169 png_destroy_read_struct(&png_ptr, &info_ptr,
2170 &end_info);
2171
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2172It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2173point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2174
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2175 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2176 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2177 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2178 more of
2179 PNG_FREE_PLTE, PNG_FREE_TRNS,
2180 PNG_FREE_HIST, PNG_FREE_ICCP,
2181 PNG_FREE_PCAL, PNG_FREE_ROWS,
2182 PNG_FREE_SCAL, PNG_FREE_SPLT,
2183 PNG_FREE_TEXT, PNG_FREE_UNKN,
2184 or simply PNG_FREE_ALL
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2185 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2186 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2187
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2188This function may be safely called when the relevant storage has
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]2189already been freed, or has not yet been allocated, or was allocated
2190by the user and not by libpng, and will in those
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2191cases do nothing. The "seq" parameter is ignored if only one item
2192of the selected data type, such as PLTE, is allowed. If "seq" is not
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]2193-1, and multiple items are allowed for the data type identified in
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2194the mask, such as text or sPLT, only the n'th item in the structure
2195is freed, where n is "seq".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2196
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2197The default behavior is only to free data that was allocated internally
2198by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2199or so that it will free data that was allocated by the user with png_malloc()
2200or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2201
2202 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2203 mask - which data elements are affected
2204 same choices as in png_free_data()
2205 freer - one of
2206 PNG_DESTROY_WILL_FREE_DATA
2207 PNG_SET_WILL_FREE_DATA
2208 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2209
2210This function only affects data that has already been allocated.
2211You can call this function after reading the PNG data but before calling
2212any png_set_*() functions, to control whether the user or the png_set_*()
2213function is responsible for freeing any existing data that might be present,
2214and again after the png_set_*() functions to control whether the user
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2215or png_destroy_*() is supposed to free the data. When the user assumes
2216responsibility for libpng-allocated data, the application must use
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2217png_free() to free it, and when the user transfers responsibility to libpng
2218for data that the user has allocated, the user must have used png_malloc()
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]2219or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2220
2221If you allocated your row_pointers in a single block, as suggested above in
2222the description of the high level read interface, you must not transfer
2223responsibility for freeing it to the png_set_rows or png_read_destroy function,
2224because they would also try to free the individual row_pointers[i].
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2225
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2226If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
2227separately, do not transfer responsibility for freeing text_ptr to libpng,
2228because when libpng fills a png_text structure it combines these members with
2229the key member, and png_free_data() will free only text_ptr.key. Similarly,
2230if you transfer responsibility for free'ing text_ptr from libpng to your
2231application, your application must not separately free those members.
2232
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2233The png_free_data() function will turn off the "valid" flag for anything
2234it frees. If you need to turn the flag off for a chunk that was freed by your
2235application instead of by libpng, you can use
2236
2237 png_set_invalid(png_ptr, info_ptr, mask);
2238 mask - identifies the chunks to be made invalid,
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2239 containing the bitwise OR of one or
Glenn Randers-Pehrsond56aca72000-11-23 11:51:42 -0600[diff] [blame]2240 more of
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]2241 PNG_INFO_gAMA, PNG_INFO_sBIT,
2242 PNG_INFO_cHRM, PNG_INFO_PLTE,
2243 PNG_INFO_tRNS, PNG_INFO_bKGD,
2244 PNG_INFO_hIST, PNG_INFO_pHYs,
2245 PNG_INFO_oFFs, PNG_INFO_tIME,
2246 PNG_INFO_pCAL, PNG_INFO_sRGB,
2247 PNG_INFO_iCCP, PNG_INFO_sPLT,
2248 PNG_INFO_sCAL, PNG_INFO_IDAT
2249
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2250For a more compact example of reading a PNG image, see the file example.c.
2251
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2252.SS Reading PNG files progressively
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2253
2254The progressive reader is slightly different then the non-progressive
2255reader. Instead of calling png_read_info(), png_read_rows(), and
2256png_read_end(), you make one call to png_process_data(), which calls
2257callbacks when it has the info, a row, or the end of the image. You
2258set up these callbacks with png_set_progressive_read_fn(). You don't
2259have to worry about the input/output functions of libpng, as you are
2260giving the library the data directly in png_process_data(). I will
2261assume that you have read the section on reading PNG files above,
2262so I will only highlight the differences (although I will show
2263all of the code).
2264
2265png_structp png_ptr;
2266png_infop info_ptr;
2267
2268 /* An example code fragment of how you would
2269 initialize the progressive reader in your
2270 application. */
2271 int
2272 initialize_png_reader()
2273 {
2274 png_ptr = png_create_read_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2275 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2276 user_error_fn, user_warning_fn);
2277 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2278 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2279 info_ptr = png_create_info_struct(png_ptr);
2280 if (!info_ptr)
2281 {
2282 png_destroy_read_struct(&png_ptr, (png_infopp)NULL,
2283 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2284 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2285 }
2286
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2287 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2288 {
2289 png_destroy_read_struct(&png_ptr, &info_ptr,
2290 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2291 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2292 }
2293
2294 /* This one's new. You can provide functions
2295 to be called when the header info is valid,
2296 when each row is completed, and when the image
2297 is finished. If you aren't using all functions,
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2298 you can specify NULL parameters. Even when all
2299 three functions are NULL, you need to call
2300 png_set_progressive_read_fn(). You can use
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2301 any struct as the user_ptr (cast to a void pointer
2302 for the function call), and retrieve the pointer
2303 from inside the callbacks using the function
2304
2305 png_get_progressive_ptr(png_ptr);
2306
2307 which will return a void pointer, which you have
2308 to cast appropriately.
2309 */
2310 png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
2311 info_callback, row_callback, end_callback);
2312
2313 return 0;
2314 }
2315
2316 /* A code fragment that you call as you receive blocks
2317 of data */
2318 int
2319 process_data(png_bytep buffer, png_uint_32 length)
2320 {
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2321 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2322 {
2323 png_destroy_read_struct(&png_ptr, &info_ptr,
2324 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2325 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2326 }
2327
2328 /* This one's new also. Simply give it a chunk
2329 of data from the file stream (in order, of
2330 course). On machines with segmented memory
2331 models machines, don't give it any more than
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2332 64K. The library seems to run fine with sizes
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2333 of 4K. Although you can give it much less if
2334 necessary (I assume you can give it chunks of
2335 1 byte, I haven't tried less then 256 bytes
2336 yet). When this function returns, you may
2337 want to display any rows that were generated
2338 in the row callback if you don't already do
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2339 so there.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2340 */
2341 png_process_data(png_ptr, info_ptr, buffer, length);
2342 return 0;
2343 }
2344
2345 /* This function is called (as set by
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2346 png_set_progressive_read_fn() above) when enough data
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2347 has been supplied so all of the header has been
2348 read.
2349 */
2350 void
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2351 info_callback(png_structp png_ptr, png_infop info)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2352 {
2353 /* Do any setup here, including setting any of
2354 the transformations mentioned in the Reading
2355 PNG files section. For now, you _must_ call
2356 either png_start_read_image() or
2357 png_read_update_info() after all the
2358 transformations are set (even if you don't set
2359 any). You may start getting rows before
2360 png_process_data() returns, so this is your
2361 last chance to prepare for that.
2362 */
2363 }
2364
2365 /* This function is called when each row of image
2366 data is complete */
2367 void
2368 row_callback(png_structp png_ptr, png_bytep new_row,
Glenn Randers-Pehrsone68f5a32001-05-14 09:20:53 -0500[diff] [blame]2369 png_uint_32 row_num, int pass)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2370 {
2371 /* If the image is interlaced, and you turned
2372 on the interlace handler, this function will
2373 be called for every row in every pass. Some
2374 of these rows will not be changed from the
2375 previous pass. When the row is not changed,
2376 the new_row variable will be NULL. The rows
2377 and passes are called in order, so you don't
2378 really need the row_num and pass, but I'm
2379 supplying them because it may make your life
2380 easier.
2381
2382 For the non-NULL rows of interlaced images,
2383 you must call png_progressive_combine_row()
2384 passing in the row and the old row. You can
2385 call this function for NULL rows (it will just
2386 return) and for non-interlaced images (it just
2387 does the memcpy for you) if it will make the
2388 code easier. Thus, you can just do this for
2389 all cases:
2390 */
2391
2392 png_progressive_combine_row(png_ptr, old_row,
2393 new_row);
2394
2395 /* where old_row is what was displayed for
Glenn Randers-Pehrson345bc271998-06-14 14:43:31 -0500[diff] [blame]2396 previously for the row. Note that the first
2397 pass (pass == 0, really) will completely cover
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2398 the old row, so the rows do not have to be
2399 initialized. After the first pass (and only
2400 for interlaced images), you will have to pass
2401 the current row, and the function will combine
2402 the old row and the new row.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2403 */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2404 }
2405
2406 void
2407 end_callback(png_structp png_ptr, png_infop info)
2408 {
2409 /* This function is called after the whole image
2410 has been read, including any chunks after the
2411 image (up to and including the IEND). You
2412 will usually have the same info chunk as you
2413 had in the header, although some data may have
2414 been added to the comments and time fields.
2415
2416 Most people won't do much here, perhaps setting
2417 a flag that marks the image as finished.
2418 */
2419 }
2420
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]2421
2422
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2423.SH IV. Writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2424
2425Much of this is very similar to reading. However, everything of
2426importance is repeated here, so you won't have to constantly look
2427back up in the reading section to understand writing.
2428
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2429.SS Setup
2430
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2431You will want to do the I/O initialization before you get into libpng,
2432so if it doesn't work, you don't have anything to undo. If you are not
2433using the standard I/O functions, you will need to replace them with
2434custom writing functions. See the discussion under Customizing libpng.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2435
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2436 FILE *fp = fopen(file_name, "wb");
2437 if (!fp)
2438 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2439 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2440 }
2441
2442Next, png_struct and png_info need to be allocated and initialized.
2443As these can be both relatively large, you may not want to store these
2444on the stack, unless you have stack space to spare. Of course, you
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2445will want to check if they return NULL. If you are also reading,
2446you won't want to name your read structure and your write structure
2447both "png_ptr"; you can call them anything you like, such as
2448"read_ptr" and "write_ptr". Look at pngtest.c, for example.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2449
2450 png_structp png_ptr = png_create_write_struct
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]2451 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2452 user_error_fn, user_warning_fn);
2453 if (!png_ptr)
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2454 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2455
2456 png_infop info_ptr = png_create_info_struct(png_ptr);
2457 if (!info_ptr)
2458 {
2459 png_destroy_write_struct(&png_ptr,
2460 (png_infopp)NULL);
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2461 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2462 }
2463
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]2464If you want to use your own memory allocation routines,
2465define PNG_USER_MEM_SUPPORTED and use
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2466png_create_write_struct_2() instead of png_create_write_struct():
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]2467
2468 png_structp png_ptr = png_create_write_struct_2
2469 (PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
2470 user_error_fn, user_warning_fn, (png_voidp)
2471 user_mem_ptr, user_malloc_fn, user_free_fn);
2472
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2473After you have these structures, you will need to set up the
2474error handling. When libpng encounters an error, it expects to
2475longjmp() back to your routine. Therefore, you will need to call
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2476setjmp() and pass the png_jmpbuf(png_ptr). If you
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2477write the file from different routines, you will need to update
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2478the png_jmpbuf(png_ptr) every time you enter a new routine that will
2479call a png_*() function. See your documentation of setjmp/longjmp
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2480for your compiler for more information on setjmp/longjmp. See
2481the discussion on libpng error handling in the Customizing Libpng
2482section below for more information on the libpng error handling.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2483
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]2484 if (setjmp(png_jmpbuf(png_ptr)))
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2485 {
Glenn Randers-Pehrson104622b2000-05-29 08:58:03 -0500[diff] [blame]2486 png_destroy_write_struct(&png_ptr, &info_ptr);
2487 fclose(fp);
2488 return (ERROR);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2489 }
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2490 ...
2491 return;
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2492
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2493If you would rather avoid the complexity of setjmp/longjmp issues,
2494you can compile libpng with PNG_SETJMP_NOT_SUPPORTED, in which case
2495errors will result in a call to PNG_ABORT() which defaults to abort().
2496
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2497Now you need to set up the output code. The default for libpng is to
2498use the C function fwrite(). If you use this, you will need to pass a
2499valid FILE * in the function png_init_io(). Be sure that the file is
2500opened in binary mode. Again, if you wish to handle writing data in
2501another way, see the discussion on libpng I/O handling in the Customizing
2502Libpng section below.
2503
2504 png_init_io(png_ptr, fp);
2505
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]2506If you are embedding your PNG into a datastream such as MNG, and don't
2507want libpng to write the 8-byte signature, or if you have already
2508written the signature in your application, use
2509
2510 png_set_sig_bytes(png_ptr, 8);
2511
2512to inform libpng that it should not write a signature.
2513
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2514.SS Write callbacks
2515
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2516At this point, you can set up a callback function that will be
2517called after each row has been written, which you can use to control
2518a progress meter or the like. It's demonstrated in pngtest.c.
2519You must supply a function
2520
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2521 void write_row_callback(png_ptr, png_uint_32 row,
2522 int pass);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]2523 {
2524 /* put your code here */
2525 }
2526
2527(You can give it another name that you like instead of "write_row_callback")
2528
2529To inform libpng about your function, use
2530
2531 png_set_write_status_fn(png_ptr, write_row_callback);
2532
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2533You now have the option of modifying how the compression library will
2534run. The following functions are mainly for testing, but may be useful
2535in some cases, like if you need to write PNG files extremely fast and
2536are willing to give up some compression, or if you want to get the
2537maximum possible compression at the expense of slower writing. If you
2538have no special needs in this area, let the library do what it wants by
2539not calling this function at all, as it has been tuned to deliver a good
2540speed/compression ratio. The second parameter to png_set_filter() is
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2541the filter method, for which the only valid values are 0 (as of the
2542July 1999 PNG specification, version 1.2) or 64 (if you are writing
2543a PNG datastream that is to be embedded in a MNG datastream). The third
2544parameter is a flag that indicates which filter type(s) are to be tested
2545for each scanline. See the PNG specification for details on the specific filter
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]2546types.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2547
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2548
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2549 /* turn on or off filtering, and/or choose
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2550 specific filters. You can use either a single
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2551 PNG_FILTER_VALUE_NAME or the bitwise OR of one
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2552 or more PNG_FILTER_NAME masks. */
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2553 png_set_filter(png_ptr, 0,
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2554 PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
2555 PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
2556 PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]2557 PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2558 PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
2559 PNG_ALL_FILTERS);
2560
2561If an application
2562wants to start and stop using particular filters during compression,
2563it should start out with all of the filters (to ensure that the previous
2564row of pixels will be stored in case it's needed later), and then add
2565and remove them after the start of compression.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2566
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2567If you are writing a PNG datastream that is to be embedded in a MNG
2568datastream, the second parameter can be either 0 or 64.
2569
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]2570The png_set_compression_*() functions interface to the zlib compression
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2571library, and should mostly be ignored unless you really know what you are
2572doing. The only generally useful call is png_set_compression_level()
2573which changes how much time zlib spends on trying to compress the image
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2574data. See the Compression Library (zlib.h and algorithm.txt, distributed
2575with zlib) for details on the compression levels.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2576
2577 /* set the zlib compression level */
2578 png_set_compression_level(png_ptr,
2579 Z_BEST_COMPRESSION);
2580
2581 /* set other zlib parameters */
2582 png_set_compression_mem_level(png_ptr, 8);
2583 png_set_compression_strategy(png_ptr,
2584 Z_DEFAULT_STRATEGY);
2585 png_set_compression_window_bits(png_ptr, 15);
2586 png_set_compression_method(png_ptr, 8);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2587 png_set_compression_buffer_size(png_ptr, 8192)
2588
2589extern PNG_EXPORT(void,png_set_zbuf_size)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2590
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2591.SS Setting the contents of info for output
2592
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2593You now need to fill in the png_info structure with all the data you
2594wish to write before the actual image. Note that the only thing you
2595are allowed to write after the image is the text chunks and the time
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]2596chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2597the latest PNG specification for more information on that. If you
2598wish to write them before the image, fill them in now, and flag that
2599data as being valid. If you want to wait until after the data, don't
2600fill them until png_write_end(). For all the fields in png_info and
2601their data types, see png.h. For explanations of what the fields
2602contain, see the PNG specification.
2603
2604Some of the more important parts of the png_info are:
2605
2606 png_set_IHDR(png_ptr, info_ptr, width, height,
2607 bit_depth, color_type, interlace_type,
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2608 compression_type, filter_method)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2609 width - holds the width of the image
2610 in pixels (up to 2^31).
2611 height - holds the height of the image
2612 in pixels (up to 2^31).
2613 bit_depth - holds the bit depth of one of the
2614 image channels.
2615 (valid values are 1, 2, 4, 8, 16
2616 and depend also on the
2617 color_type. See also significant
2618 bits (sBIT) below).
2619 color_type - describes which color/alpha
2620 channels are present.
2621 PNG_COLOR_TYPE_GRAY
2622 (bit depths 1, 2, 4, 8, 16)
2623 PNG_COLOR_TYPE_GRAY_ALPHA
2624 (bit depths 8, 16)
2625 PNG_COLOR_TYPE_PALETTE
2626 (bit depths 1, 2, 4, 8)
2627 PNG_COLOR_TYPE_RGB
2628 (bit_depths 8, 16)
2629 PNG_COLOR_TYPE_RGB_ALPHA
2630 (bit_depths 8, 16)
2631
2632 PNG_COLOR_MASK_PALETTE
2633 PNG_COLOR_MASK_COLOR
2634 PNG_COLOR_MASK_ALPHA
2635
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2636 interlace_type - PNG_INTERLACE_NONE or
2637 PNG_INTERLACE_ADAM7
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2638 compression_type - (must be
2639 PNG_COMPRESSION_TYPE_DEFAULT)
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]2640 filter_method - (must be PNG_FILTER_TYPE_DEFAULT
2641 or, if you are writing a PNG to
2642 be embedded in a MNG datastream,
2643 can also be
2644 PNG_INTRAPIXEL_DIFFERENCING)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2645
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]2646If you call png_set_IHDR(), the call must appear before any of the
2647other png_set_*() functions, which might require access to some of
2648the IHDR settings. The remaining png_set_*() functions can be called
2649in any order.
2650
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]2651If you wish, you can reset the compression_type, interlace_type, or
2652filter_method later by calling png_set_IHDR() again; if you do this, the
2653width, height, bit_depth, and color_type must be the same in each call.
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]2654
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2655 png_set_PLTE(png_ptr, info_ptr, palette,
2656 num_palette);
2657 palette - the palette for the file
2658 (array of png_color)
2659 num_palette - number of entries in the palette
2660
2661 png_set_gAMA(png_ptr, info_ptr, gamma);
2662 gamma - the gamma the image was created
2663 at (PNG_INFO_gAMA)
2664
2665 png_set_sRGB(png_ptr, info_ptr, srgb_intent);
2666 srgb_intent - the rendering intent
2667 (PNG_INFO_sRGB) The presence of
2668 the sRGB chunk means that the pixel
2669 data is in the sRGB color space.
2670 This chunk also implies specific
2671 values of gAMA and cHRM. Rendering
2672 intent is the CSS-1 property that
2673 has been defined by the International
2674 Color Consortium
2675 (http://www.color.org).
2676 It can be one of
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]2677 PNG_sRGB_INTENT_SATURATION,
2678 PNG_sRGB_INTENT_PERCEPTUAL,
2679 PNG_sRGB_INTENT_ABSOLUTE, or
2680 PNG_sRGB_INTENT_RELATIVE.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2681
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2682
2683 png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
2684 srgb_intent);
2685 srgb_intent - the rendering intent
2686 (PNG_INFO_sRGB) The presence of the
2687 sRGB chunk means that the pixel
2688 data is in the sRGB color space.
2689 This function also causes gAMA and
2690 cHRM chunks with the specific values
2691 that are consistent with sRGB to be
2692 written.
2693
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2694 png_set_iCCP(png_ptr, info_ptr, name, compression_type,
2695 profile, proflen);
2696 name - The profile name.
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2697 compression - The compression type; always
2698 PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
2699 You may give NULL to this argument to
2700 ignore it.
2701 profile - International Color Consortium color
2702 profile data. May contain NULs.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2703 proflen - length of profile data in bytes.
2704
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2705 png_set_sBIT(png_ptr, info_ptr, sig_bit);
2706 sig_bit - the number of significant bits for
2707 (PNG_INFO_sBIT) each of the gray, red,
2708 green, and blue channels, whichever are
2709 appropriate for the given color type
2710 (png_color_16)
2711
2712 png_set_tRNS(png_ptr, info_ptr, trans, num_trans,
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]2713 trans_color);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2714 trans - array of transparent entries for
2715 palette (PNG_INFO_tRNS)
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]2716 trans_color - graylevel or color sample values
2717 (in order red, green, blue) of the
2718 single transparent color for
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]2719 non-paletted images (PNG_INFO_tRNS)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2720 num_trans - number of transparent entries
2721 (PNG_INFO_tRNS)
2722
2723 png_set_hIST(png_ptr, info_ptr, hist);
2724 (PNG_INFO_hIST)
2725 hist - histogram of palette (array of
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2726 png_uint_16)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2727
2728 png_set_tIME(png_ptr, info_ptr, mod_time);
2729 mod_time - time image was last modified
2730 (PNG_VALID_tIME)
2731
2732 png_set_bKGD(png_ptr, info_ptr, background);
2733 background - background color (PNG_VALID_bKGD)
2734
2735 png_set_text(png_ptr, info_ptr, text_ptr, num_text);
2736 text_ptr - array of png_text holding image
2737 comments
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2738 text_ptr[i].compression - type of compression used
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2739 on "text" PNG_TEXT_COMPRESSION_NONE
2740 PNG_TEXT_COMPRESSION_zTXt
2741 PNG_ITXT_COMPRESSION_NONE
2742 PNG_ITXT_COMPRESSION_zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2743 text_ptr[i].key - keyword for comment. Must contain
2744 1-79 characters.
2745 text_ptr[i].text - text comments for current
2746 keyword. Can be NULL or empty.
2747 text_ptr[i].text_length - length of text string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2748 after decompression, 0 for iTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2749 text_ptr[i].itxt_length - length of itxt string,
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2750 after decompression, 0 for tEXt/zTXt
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2751 text_ptr[i].lang - language of comment (NULL or
2752 empty for unknown).
2753 text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
2754 or empty for unknown).
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2755 num_text - number of comments
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2756
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2757 png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
2758 num_spalettes);
2759 palette_ptr - array of png_sPLT_struct structures
2760 to be added to the list of palettes
2761 in the info structure.
2762 num_spalettes - number of palette structures to be
2763 added.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2764
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2765 png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
2766 unit_type);
2767 offset_x - positive offset from the left
2768 edge of the screen
2769 offset_y - positive offset from the top
2770 edge of the screen
2771 unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
2772
2773 png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
2774 unit_type);
2775 res_x - pixels/unit physical resolution
2776 in x direction
2777 res_y - pixels/unit physical resolution
2778 in y direction
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2779 unit_type - PNG_RESOLUTION_UNKNOWN,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2780 PNG_RESOLUTION_METER
2781
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2782 png_set_sCAL(png_ptr, info_ptr, unit, width, height)
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2783 unit - physical scale units (an integer)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2784 width - width of a pixel in physical scale units
2785 height - height of a pixel in physical scale units
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2786 (width and height are doubles)
2787
2788 png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
2789 unit - physical scale units (an integer)
2790 width - width of a pixel in physical scale units
2791 height - height of a pixel in physical scale units
2792 (width and height are strings like "2.54")
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2793
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2794 png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
2795 num_unknowns)
2796 unknowns - array of png_unknown_chunk
2797 structures holding unknown chunks
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2798 unknowns[i].name - name of unknown chunk
2799 unknowns[i].data - data of unknown chunk
Glenn Randers-Pehrson4accabb2000-04-14 14:20:47 -0500[diff] [blame]2800 unknowns[i].size - size of unknown chunk's data
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2801 unknowns[i].location - position to write chunk in file
2802 0: do not write chunk
2803 PNG_HAVE_IHDR: before PLTE
2804 PNG_HAVE_PLTE: before IDAT
2805 PNG_AFTER_IDAT: after IDAT
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2806
2807The "location" member is set automatically according to
2808what part of the output file has already been written.
2809You can change its value after calling png_set_unknown_chunks()
2810as demonstrated in pngtest.c. Within each of the "locations",
2811the chunks are sequenced according to their position in the
2812structure (that is, the value of "i", which is the order in which
2813the chunk was either read from the input file or defined with
2814png_set_unknown_chunks).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2815
2816A quick word about text and num_text. text is an array of png_text
2817structures. num_text is the number of valid structures in the array.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2818Each png_text structure holds a language code, a keyword, a text value,
2819and a compression type.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2820
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2821The compression types have the same valid numbers as the compression
2822types of the image data. Currently, the only valid number is zero.
2823However, you can store text either compressed or uncompressed, unlike
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2824images, which always have to be compressed. So if you don't want the
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2825text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]2826Because tEXt and zTXt chunks don't have a language field, if you
2827specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
2828any language code or translated keyword will not be written out.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2829
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2830Until text gets around 1000 bytes, it is not worth compressing it.
2831After the text has been written out to the file, the compression type
2832is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
2833so that it isn't written out again at the end (in case you are calling
2834png_write_end() with the same struct.
2835
2836The keywords that are given in the PNG Specification are:
2837
2838 Title Short (one line) title or
2839 caption for image
2840 Author Name of image's creator
2841 Description Description of image (possibly long)
2842 Copyright Copyright notice
2843 Creation Time Time of original image creation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2844 (usually RFC 1123 format, see below)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2845 Software Software used to create the image
2846 Disclaimer Legal disclaimer
2847 Warning Warning of nature of content
2848 Source Device used to create the image
2849 Comment Miscellaneous comment; conversion
2850 from other image format
2851
2852The keyword-text pairs work like this. Keywords should be short
2853simple descriptions of what the comment is about. Some typical
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2854keywords are found in the PNG specification, as is some recommendations
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2855on keywords. You can repeat keywords in a file. You can even write
2856some text before the image and some after. For example, you may want
2857to put a description of the image before the image, but leave the
2858disclaimer until after, so viewers working over modem connections
2859don't have to wait for the disclaimer to go over the modem before
2860they start seeing the image. Finally, keywords should be full
2861words, not abbreviations. Keywords and text are in the ISO 8859-1
2862(Latin-1) character set (a superset of regular ASCII) and can not
2863contain NUL characters, and should not contain control or other
2864unprintable characters. To make the comments widely readable, stick
2865with basic ASCII, and avoid machine specific character set extensions
2866like the IBM-PC character set. The keyword must be present, but
2867you can leave off the text string on non-compressed pairs.
2868Compressed pairs must have a text string, as only the text string
2869is compressed anyway, so the compression would be meaningless.
2870
2871PNG supports modification time via the png_time structure. Two
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2872conversion routines are provided, png_convert_from_time_t() for
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2873time_t and png_convert_from_struct_tm() for struct tm. The
2874time_t routine uses gmtime(). You don't have to use either of
2875these, but if you wish to fill in the png_time structure directly,
2876you should provide the time in universal time (GMT) if possible
2877instead of your local time. Note that the year number is the full
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2878year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2879that months start with 1.
2880
2881If you want to store the time of the original image creation, you should
2882use a plain tEXt chunk with the "Creation Time" keyword. This is
2883necessary because the "creation time" of a PNG image is somewhat vague,
2884depending on whether you mean the PNG file, the time the image was
2885created in a non-PNG format, a still photo from which the image was
2886scanned, or possibly the subject matter itself. In order to facilitate
2887machine-readable dates, it is recommended that the "Creation Time"
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]2888tEXt 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]2889although this isn't a requirement. Unlike the tIME chunk, the
2890"Creation Time" tEXt chunk is not expected to be automatically changed
2891by the software. To facilitate the use of RFC 1123 dates, a function
2892png_convert_to_rfc1123(png_timep) is provided to convert from PNG
2893time to an RFC 1123 format string.
2894
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2895.SS Writing unknown chunks
2896
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2897You can use the png_set_unknown_chunks function to queue up chunks
2898for writing. You give it a chunk name, raw data, and a size; that's
2899all there is to it. The chunks will be written by the next following
2900png_write_info_before_PLTE, png_write_info, or png_write_end function.
2901Any chunks previously read into the info structure's unknown-chunk
2902list will also be written out in a sequence that satisfies the PNG
2903specification's ordering rules.
2904
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2905.SS The high-level write interface
2906
2907At this point there are two ways to proceed; through the high-level
2908write interface, or through a sequence of low-level write operations.
2909You can use the high-level interface if your image data is present
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]2910in the info structure. All defined output
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]2911transformations are permitted, enabled by the following masks.
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2912
2913 PNG_TRANSFORM_IDENTITY No transformation
2914 PNG_TRANSFORM_PACKING Pack 1, 2 and 4-bit samples
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2915 PNG_TRANSFORM_PACKSWAP Change order of packed
2916 pixels to LSB first
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2917 PNG_TRANSFORM_INVERT_MONO Invert monochrome images
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]2918 PNG_TRANSFORM_SHIFT Normalize pixels to the
2919 sBIT depth
2920 PNG_TRANSFORM_BGR Flip RGB to BGR, RGBA
2921 to BGRA
2922 PNG_TRANSFORM_SWAP_ALPHA Flip RGBA to ARGB or GA
2923 to AG
2924 PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
2925 to transparency
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2926 PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
Glenn Randers-Pehrson1eb14e92008-12-10 07:14:45 -0600[diff] [blame]2927 PNG_TRANSFORM_STRIP_FILLER Strip out filler
2928 bytes (deprecated).
2929 PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
2930 filler bytes
2931 PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
2932 filler bytes
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2933
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]2934If you have valid image data in the info structure (you can use
2935png_set_rows() to put image data in the info structure), simply do this:
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2936
2937 png_write_png(png_ptr, info_ptr, png_transforms, NULL)
2938
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]2939where png_transforms is an integer containing the bitwise OR of some set of
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2940transformation flags. This call is equivalent to png_write_info(),
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2941followed the set of transformations indicated by the transform mask,
2942then png_write_image(), and finally png_write_end().
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2943
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]2944(The final parameter of this call is not yet used. Someday it might point
2945to transformation parameters required by some future output transform.)
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2946
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]2947You must use png_transforms and not call any png_set_transform() functions
2948when you use png_write_png().
2949
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2950.SS The low-level write interface
2951
2952If you are going the low-level route instead, you are now ready to
2953write all the file information up to the actual image data. You do
2954this with a call to png_write_info().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2955
2956 png_write_info(png_ptr, info_ptr);
2957
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]2958Note that there is one transformation you may need to do before
2959png_write_info(). In PNG files, the alpha channel in an image is the
2960level of opacity. If your data is supplied as a level of
2961transparency, you can invert the alpha channel before you write it, so
2962that 0 is fully transparent and 255 (in 8-bit or paletted images) or
296365535 (in 16-bit images) is fully opaque, with
2964
2965 png_set_invert_alpha(png_ptr);
2966
2967This must appear before png_write_info() instead of later with the
2968other transformations because in the case of paletted images the tRNS
2969chunk data has to be inverted before the tRNS chunk is written. If
2970your image is not a paletted image, the tRNS data (which in such cases
2971represents a single color to be rendered as transparent) won't need to
2972be changed, and you can safely do this transformation after your
2973png_write_info() call.
2974
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]2975If you need to write a private chunk that you want to appear before
2976the PLTE chunk when PLTE is present, you can write the PNG info in
2977two steps, and insert code to write your own chunk between them:
2978
2979 png_write_info_before_PLTE(png_ptr, info_ptr);
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]2980 png_set_unknown_chunks(png_ptr, info_ptr, ...);
Glenn Randers-Pehrson5379b241999-11-27 10:22:33 -0600[diff] [blame]2981 png_write_info(png_ptr, info_ptr);
2982
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2983After you've written the file information, you can set up the library
2984to handle any special transformations of the image data. The various
2985ways to transform the data will be described in the order that they
2986should occur. This is important, as some of these change the color
2987type and/or bit depth of the data, and some others only work on
2988certain color types and bit depths. Even though each transformation
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]2989checks 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]2990make sure to only enable a transformation if it will be valid for the
2991data. For example, don't swap red and blue on grayscale data.
2992
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]2993PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]2994the 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]2995to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
2996bytes per pixel).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]2997
2998 png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
2999
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3000where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3001PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
3002is stored XRGB or RGBX.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3003
3004PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
3005they can, resulting in, for example, 8 pixels per byte for 1 bit files.
3006If the data is supplied at 1 pixel per byte, use this code, which will
3007correctly pack the pixels into a single byte:
3008
3009 png_set_packing(png_ptr);
3010
3011PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
3012data is of another bit depth, you can write an sBIT chunk into the
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3013file so that decoders can recover the original data if desired.
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3014
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3015 /* Set the true bit depth of the image data */
3016 if (color_type & PNG_COLOR_MASK_COLOR)
3017 {
3018 sig_bit.red = true_bit_depth;
3019 sig_bit.green = true_bit_depth;
3020 sig_bit.blue = true_bit_depth;
3021 }
3022 else
3023 {
3024 sig_bit.gray = true_bit_depth;
3025 }
3026 if (color_type & PNG_COLOR_MASK_ALPHA)
3027 {
3028 sig_bit.alpha = true_bit_depth;
3029 }
3030
3031 png_set_sBIT(png_ptr, info_ptr, &sig_bit);
3032
3033If 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]3034one 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]3035this will scale the values to appear to be the correct bit depth as
3036is required by PNG.
3037
3038 png_set_shift(png_ptr, &sig_bit);
3039
3040PNG files store 16 bit pixels in network byte order (big-endian,
3041ie. most significant bits first). This code would be used if they are
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3042supplied the other way (little-endian, i.e. least significant bits
3043first, the way PCs store them):
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3044
3045 if (bit_depth > 8)
3046 png_set_swap(png_ptr);
3047
3048If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
3049need to change the order the pixels are packed into bytes, you can use:
3050
3051 if (bit_depth < 8)
3052 png_set_packswap(png_ptr);
3053
3054PNG files store 3 color pixels in red, green, blue order. This code
3055would be used if they are supplied as blue, green, red:
3056
3057 png_set_bgr(png_ptr);
3058
3059PNG files describe monochrome as black being zero and white being
3060one. This code would be used if the pixels are supplied with this reversed
3061(black being one and white being zero):
3062
3063 png_set_invert_mono(png_ptr);
3064
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3065Finally, you can write your own transformation function if none of
3066the existing ones meets your needs. This is done by setting a callback
3067with
3068
3069 png_set_write_user_transform_fn(png_ptr,
3070 write_transform_fn);
3071
3072You must supply the function
3073
3074 void write_transform_fn(png_ptr ptr, row_info_ptr
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3075 row_info, png_bytep data)
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3076
3077See pngtest.c for a working example. Your function will be called
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3078before any of the other transformations are processed.
3079
3080You can also set up a pointer to a user structure for use by your
3081callback function.
3082
3083 png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
3084
3085The user_channels and user_depth parameters of this function are ignored
3086when writing; you can set them to zero as shown.
3087
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3088You can retrieve the pointer via the function png_get_user_transform_ptr().
3089For example:
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3090
3091 voidp write_user_transform_ptr =
3092 png_get_user_transform_ptr(png_ptr);
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3093
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3094It is possible to have libpng flush any pending output, either manually,
3095or automatically after a certain number of lines have been written. To
3096flush the output stream a single time call:
3097
3098 png_write_flush(png_ptr);
3099
3100and to have libpng flush the output stream periodically after a certain
3101number of scanlines have been written, call:
3102
3103 png_set_flush(png_ptr, nrows);
3104
3105Note that the distance between rows is from the last time png_write_flush()
3106was called, or the first row of the image if it has never been called.
3107So if you write 50 lines, and then png_set_flush 25, it will flush the
3108output on the next scanline, and every 25 lines thereafter, unless
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3109png_write_flush() is called before 25 more lines have been written.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3110If 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]3111RGB image) the image compression may decrease noticeably (although this
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3112may be acceptable for real-time applications). Infrequent flushing will
3113only degrade the compression performance by a few percent over images
3114that do not use flushing.
3115
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3116.SS Writing the image data
3117
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3118That's it for the transformations. Now you can write the image data.
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3119The 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]3120whole image in memory, you can just call png_write_image() and libpng
3121will write the image. You will need to pass in an array of pointers to
3122each row. This function automatically handles interlacing, so you don't
3123need to call png_set_interlace_handling() or call this function multiple
3124times, or any of that other stuff necessary with png_write_rows().
3125
3126 png_write_image(png_ptr, row_pointers);
3127
3128where row_pointers is:
3129
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3130 png_byte *row_pointers[height];
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3131
3132You can point to void or char or whatever you use for pixels.
3133
Glenn Randers-Pehrson896239b1998-04-21 15:03:57 -0500[diff] [blame]3134If you don't want to write the whole image at once, you can
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3135use png_write_rows() instead. If the file is not interlaced,
3136this is simple:
3137
3138 png_write_rows(png_ptr, row_pointers,
3139 number_of_rows);
3140
3141row_pointers is the same as in the png_write_image() call.
3142
3143If 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]3144a single row_pointer instead of an array of row_pointers:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3145
3146 png_bytep row_pointer = row;
3147
Glenn Randers-Pehrson520a7642000-03-21 05:13:06 -0600[diff] [blame]3148 png_write_row(png_ptr, row_pointer);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3149
3150When the file is interlaced, things can get a good deal more
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3151complicated. The only currently (as of the PNG Specification
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3152version 1.2, dated July 1999) defined interlacing scheme for PNG files
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3153is the "Adam7" interlace scheme, that breaks down an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3154image into seven smaller images of varying size. libpng will build
3155these images for you, or you can do them yourself. If you want to
3156build them yourself, see the PNG specification for details of which
3157pixels to write when.
3158
3159If you don't want libpng to handle the interlacing details, just
3160use png_set_interlace_handling() and call png_write_rows() the
3161correct number of times to write all seven sub-images.
3162
3163If you want libpng to build the sub-images, call this before you start
3164writing any rows:
3165
3166 number_of_passes =
3167 png_set_interlace_handling(png_ptr);
3168
3169This will return the number of passes needed. Currently, this
3170is seven, but may change if another interlace type is added.
3171
3172Then write the complete image number_of_passes times.
3173
3174 png_write_rows(png_ptr, row_pointers,
3175 number_of_rows);
3176
3177As some of these rows are not used, and thus return immediately,
3178you may want to read about interlacing in the PNG specification,
3179and only update the rows that are actually used.
3180
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3181.SS Finishing a sequential write
3182
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3183After you are finished writing the image, you should finish writing
3184the file. If you are interested in writing comments or time, you should
3185pass an appropriately filled png_info pointer. If you are not interested,
3186you can pass NULL.
3187
3188 png_write_end(png_ptr, info_ptr);
3189
3190When you are done, you can free all memory used by libpng like this:
3191
3192 png_destroy_write_struct(&png_ptr, &info_ptr);
3193
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3194It is also possible to individually free the info_ptr members that
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3195point to libpng-allocated storage with the following function:
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3196
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3197 png_free_data(png_ptr, info_ptr, mask, seq)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3198 mask - identifies data to be freed, a mask
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3199 containing the bitwise OR of one or
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3200 more of
3201 PNG_FREE_PLTE, PNG_FREE_TRNS,
3202 PNG_FREE_HIST, PNG_FREE_ICCP,
3203 PNG_FREE_PCAL, PNG_FREE_ROWS,
3204 PNG_FREE_SCAL, PNG_FREE_SPLT,
3205 PNG_FREE_TEXT, PNG_FREE_UNKN,
3206 or simply PNG_FREE_ALL
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3207 seq - sequence number of item to be freed
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3208 (-1 for all items)
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3209
Glenn Randers-Pehrsonfc4a1432000-05-17 17:39:34 -0500[diff] [blame]3210This function may be safely called when the relevant storage has
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3211already been freed, or has not yet been allocated, or was allocated
3212by the user and not by libpng, and will in those
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3213cases do nothing. The "seq" parameter is ignored if only one item
3214of the selected data type, such as PLTE, is allowed. If "seq" is not
Glenn Randers-Pehrson68ea2432000-04-01 21:10:05 -0600[diff] [blame]3215-1, and multiple items are allowed for the data type identified in
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3216the mask, such as text or sPLT, only the n'th item in the structure
3217is freed, where n is "seq".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3218
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3219If you allocated data such as a palette that you passed
3220in to libpng with png_set_*, you must not free it until just before the call to
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3221png_destroy_write_struct().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3222
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3223The default behavior is only to free data that was allocated internally
3224by libpng. This can be changed, so that libpng will not free the data,
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3225or so that it will free data that was allocated by the user with png_malloc()
3226or png_zalloc() and passed in via a png_set_*() function, with
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3227
3228 png_data_freer(png_ptr, info_ptr, freer, mask)
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3229 mask - which data elements are affected
3230 same choices as in png_free_data()
3231 freer - one of
3232 PNG_DESTROY_WILL_FREE_DATA
3233 PNG_SET_WILL_FREE_DATA
3234 PNG_USER_WILL_FREE_DATA
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3235
3236For example, to transfer responsibility for some data from a read structure
3237to a write structure, you could use
3238
3239 png_data_freer(read_ptr, read_info_ptr,
3240 PNG_USER_WILL_FREE_DATA,
3241 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
3242 png_data_freer(write_ptr, write_info_ptr,
3243 PNG_DESTROY_WILL_FREE_DATA,
3244 PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
3245
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3246thereby briefly reassigning responsibility for freeing to the user but
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3247immediately afterwards reassigning it once more to the write_destroy
3248function. Having done this, it would then be safe to destroy the read
3249structure and continue to use the PLTE, tRNS, and hIST data in the write
3250structure.
3251
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3252This function only affects data that has already been allocated.
3253You can call this function before calling after the png_set_*() functions
3254to control whether the user or png_destroy_*() is supposed to free the data.
3255When the user assumes responsibility for libpng-allocated data, the
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3256application must use
3257png_free() to free it, and when the user transfers responsibility to libpng
3258for data that the user has allocated, the user must have used png_malloc()
3259or png_zalloc() to allocate it.
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3260
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3261If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
3262separately, do not transfer responsibility for freeing text_ptr to libpng,
3263because when libpng fills a png_text structure it combines these members with
3264the key member, and png_free_data() will free only text_ptr.key. Similarly,
3265if you transfer responsibility for free'ing text_ptr from libpng to your
3266application, your application must not separately free those members.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3267For a more compact example of writing a PNG image, see the file example.c.
3268
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3269.SH V. Modifying/Customizing libpng:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3270
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3271There are two issues here. The first is changing how libpng does
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3272standard things like memory allocation, input/output, and error handling.
3273The second deals with more complicated things like adding new chunks,
3274adding new transformations, and generally changing how libpng works.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]3275Both of those are compile-time issues; that is, they are generally
3276determined at the time the code is written, and there is rarely a need
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3277to provide the user with a means of changing them.
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]3278
3279Memory allocation, input/output, and error handling
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3280
3281All of the memory allocation, input/output, and error handling in libpng
Glenn Randers-Pehrson231e6872001-01-12 15:13:06 -0600[diff] [blame]3282goes through callbacks that are user-settable. The default routines are
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3283in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3284these functions, call the appropriate png_set_*_fn() function.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3285
Glenn Randers-Pehrsoncfbed9b2002-05-21 18:06:08 -0500[diff] [blame]3286Memory allocation is done through the functions png_malloc()
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3287and png_free(). These currently just call the standard C functions. If
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3288your pointers can't access more then 64K at a time, you will want to set
3289MAXSEG_64K in zlib.h. Since it is unlikely that the method of handling
3290memory allocation on a platform will change between applications, these
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3291functions must be modified in the library at compile time. If you prefer
3292to use a different method of allocating and freeing data, you can use
Glenn Randers-Pehrsoncfbed9b2002-05-21 18:06:08 -0500[diff] [blame]3293png_create_read_struct_2() or png_create_write_struct_2() to register
3294your own functions as described above.
Glenn Randers-Pehrsoncfbed9b2002-05-21 18:06:08 -0500[diff] [blame]3295These functions also provide a void pointer that can be retrieved via
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3296
3297 mem_ptr=png_get_mem_ptr(png_ptr);
3298
3299Your replacement memory functions must have prototypes as follows:
3300
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3301 png_voidp malloc_fn(png_structp png_ptr,
Glenn Randers-Pehrsonae498dc2001-11-24 14:53:31 -0600[diff] [blame]3302 png_size_t size);
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3303 void free_fn(png_structp png_ptr, png_voidp ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3304
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]3305Your malloc_fn() must return NULL in case of failure. The png_malloc()
3306function will normally call png_error() if it receives a NULL from the
3307system memory allocator or from your replacement malloc_fn().
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]3308
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3309Your free_fn() will never be called with a NULL ptr, since libpng's
3310png_free() checks for NULL before calling free_fn().
3311
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3312Input/Output in libpng is done through png_read() and png_write(),
3313which currently just call fread() and fwrite(). The FILE * is stored in
3314png_struct and is initialized via png_init_io(). If you wish to change
3315the method of I/O, the library supplies callbacks that you can set
3316through the function png_set_read_fn() and png_set_write_fn() at run
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3317time, instead of calling the png_init_io() function. These functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3318also provide a void pointer that can be retrieved via the function
3319png_get_io_ptr(). For example:
3320
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3321 png_set_read_fn(png_structp read_ptr,
3322 voidp read_io_ptr, png_rw_ptr read_data_fn)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3323
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3324 png_set_write_fn(png_structp write_ptr,
3325 voidp write_io_ptr, png_rw_ptr write_data_fn,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3326 png_flush_ptr output_flush_fn);
3327
Glenn Randers-Pehrsonf7d1a171998-06-06 15:31:35 -0500[diff] [blame]3328 voidp read_io_ptr = png_get_io_ptr(read_ptr);
3329 voidp write_io_ptr = png_get_io_ptr(write_ptr);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3330
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3331The replacement I/O functions must have prototypes as follows:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3332
3333 void user_read_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]3334 png_bytep data, png_size_t length);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3335 void user_write_data(png_structp png_ptr,
Glenn Randers-Pehrson837a3d12002-05-10 20:19:58 -0500[diff] [blame]3336 png_bytep data, png_size_t length);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3337 void user_flush_data(png_structp png_ptr);
3338
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3339The user_read_data() function is responsible for detecting and
3340handling end-of-data errors.
3341
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3342Supplying NULL for the read, write, or flush functions sets them back
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3343to using the default C stream functions, which expect the io_ptr to
3344point to a standard *FILE structure. It is probably a mistake
3345to use NULL for one of write_data_fn and output_flush_fn but not both
3346of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
3347It is an error to read from a write stream, and vice versa.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3348
3349Error handling in libpng is done through png_error() and png_warning().
3350Errors handled through png_error() are fatal, meaning that png_error()
3351should never return to its caller. Currently, this is handled via
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3352setjmp() and longjmp() (unless you have compiled libpng with
3353PNG_SETJMP_NOT_SUPPORTED, in which case it is handled via PNG_ABORT()),
3354but you could change this to do things like exit() if you should wish.
3355
3356On non-fatal errors, png_warning() is called
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3357to print a warning message, and then control returns to the calling code.
3358By default png_error() and png_warning() print a message on stderr via
Glenn Randers-Pehrson38e6e772000-04-09 19:06:13 -0500[diff] [blame]3359fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
3360(because you don't want the messages) or PNG_NO_STDIO defined (because
3361fprintf() isn't available). If you wish to change the behavior of the error
3362functions, you will need to set up your own message callbacks. These
3363functions are normally supplied at the time that the png_struct is created.
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3364It is also possible to redirect errors and warnings to your own replacement
3365functions after png_create_*_struct() has been called by calling:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3366
3367 png_set_error_fn(png_structp png_ptr,
3368 png_voidp error_ptr, png_error_ptr error_fn,
3369 png_error_ptr warning_fn);
3370
3371 png_voidp error_ptr = png_get_error_ptr(png_ptr);
3372
3373If NULL is supplied for either error_fn or warning_fn, then the libpng
3374default function will be used, calling fprintf() and/or longjmp() if a
3375problem is encountered. The replacement error functions should have
3376parameters as follows:
3377
3378 void user_error_fn(png_structp png_ptr,
3379 png_const_charp error_msg);
3380 void user_warning_fn(png_structp png_ptr,
3381 png_const_charp warning_msg);
3382
3383The motivation behind using setjmp() and longjmp() is the C++ throw and
3384catch exception handling methods. This makes the code much easier to write,
3385as there is no need to check every return code of every function call.
3386However, there are some uncertainties about the status of local variables
3387after a longjmp, so the user may want to be careful about doing anything after
3388setjmp returns non-zero besides returning itself. Consult your compiler
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3389documentation for more details. For an alternative approach, you may wish
3390to use the "cexcept" facility (see http://cexcept.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3391
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3392.SS Custom chunks
3393
3394If you need to read or write custom chunks, you may need to get deeper
3395into the libpng code. The library now has mechanisms for storing
3396and writing chunks of unknown type; you can even declare callbacks
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]3397for custom chunks. However, this may not be good enough if the
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3398library code itself needs to know about interactions between your
3399chunk and existing `intrinsic' chunks.
3400
3401If you need to write a new intrinsic chunk, first read the PNG
3402specification. Acquire a first level of
3403understanding of how it works. Pay particular attention to the
3404sections that describe chunk names, and look at how other chunks were
3405designed, so you can do things similarly. Second, check out the
3406sections of libpng that read and write chunks. Try to find a chunk
3407that is similar to yours and use it as a template. More details can
3408be found in the comments inside the code. It is best to handle unknown
3409chunks in a generic method, via callback functions, instead of by
3410modifying libpng functions.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3411
3412If you wish to write your own transformation for the data, look through
3413the part of the code that does the transformations, and check out some of
3414the simpler ones to get an idea of how they work. Try to find a similar
3415transformation to the one you want to add and copy off of it. More details
3416can be found in the comments inside the code itself.
3417
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3418.SS Configuring for 16 bit platforms
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3419
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3420You 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]3421it 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]3422won'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]3423
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3424.SS Configuring for DOS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3425
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3426For DOS users who only have access to the lower 640K, you will
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3427have to limit zlib's memory usage via a png_set_compression_mem_level()
3428call. See zlib.h or zconf.h in the zlib library for more information.
3429
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3430.SS Configuring for Medium Model
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3431
3432Libpng's support for medium model has been tested on most of the popular
3433compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
3434defined, and FAR gets defined to far in pngconf.h, and you should be
3435all set. Everything in the library (except for zlib's structure) is
3436expecting far data. You must use the typedefs with the p or pp on
3437the end for pointers (or at least look at them and be careful). Make
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3438note that the rows of data are defined as png_bytepp, which is an
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3439unsigned char far * far *.
3440
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3441.SS Configuring for gui/windowing platforms:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3442
3443You will need to write new error and warning functions that use the GUI
3444interface, as described previously, and set them to be the error and
Glenn Randers-Pehrsona77ef622000-02-18 13:48:52 -0600[diff] [blame]3445warning functions at the time that png_create_*_struct() is called,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3446in order to have them available during the structure initialization.
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3447They can be changed later via png_set_error_fn(). On some compilers,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3448you may also have to change the memory allocators (png_malloc, etc.).
3449
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3450.SS Configuring for compiler xxx:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3451
Glenn Randers-Pehrsonbeb572e2006-08-19 13:59:24 -0500[diff] [blame]3452All includes for libpng are in pngconf.h. If you need to add, change
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3453or delete an include, this is the place to do it.
3454The includes that are not needed outside libpng are placed in pngpriv.h,
3455which is only used by the routines inside libpng itself.
3456The files in libpng proper only include pngpriv.h and png.h, which
3457in turn includes pngconf.h.
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 zlib:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3460
3461There are special functions to configure the compression. Perhaps the
3462most useful one changes the compression level, which currently uses
3463input compression values in the range 0 - 9. The library normally
3464uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
3465have shown that for a large majority of images, compression values in
3466the range 3-6 compress nearly as well as higher levels, and do so much
3467faster. For online applications it may be desirable to have maximum speed
3468(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
3469specify no compression (Z_NO_COMPRESSION = 0), but this would create
3470files larger than just storing the raw bitmap. You can specify the
3471compression level by calling:
3472
3473 png_set_compression_level(png_ptr, level);
3474
3475Another useful one is to reduce the memory level used by the library.
3476The memory level defaults to 8, but it can be lowered if you are
3477short on memory (running DOS, for example, where you only have 640K).
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3478Note that the memory level does have an effect on compression; among
3479other things, lower levels will result in sections of incompressible
3480data being emitted in smaller stored blocks, with a correspondingly
3481larger relative overhead of up to 15% in the worst case.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3482
3483 png_set_compression_mem_level(png_ptr, level);
3484
3485The other functions are for configuring zlib. They are not recommended
3486for normal use and may result in writing an invalid PNG file. See
3487zlib.h for more information on what these mean.
3488
3489 png_set_compression_strategy(png_ptr,
3490 strategy);
3491 png_set_compression_window_bits(png_ptr,
3492 window_bits);
3493 png_set_compression_method(png_ptr, method);
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3494 png_set_compression_buffer_size(png_ptr, size);
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3495
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3496.SS Controlling row filtering
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3497
3498If you want to control whether libpng uses filtering or not, which
3499filters are used, and how it goes about picking row filters, you
3500can call one of these functions. The selection and configuration
3501of row filters can have a significant impact on the size and
3502encoding speed and a somewhat lesser impact on the decoding speed
3503of an image. Filtering is enabled by default for RGB and grayscale
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3504images (with and without alpha), but not for paletted images nor
3505for any images with bit depths less than 8 bits/pixel.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3506
3507The 'method' parameter sets the main filtering method, which is
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3508currently only '0' in the PNG 1.2 specification. The 'filters'
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3509parameter sets which filter(s), if any, should be used for each
3510scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
3511to turn filtering on and off, respectively.
3512
3513Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
3514PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
Glenn Randers-Pehrson6942d532000-05-01 09:31:54 -0500[diff] [blame]3515ORed together with '|' to specify one or more filters to use.
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3516These filters are described in more detail in the PNG specification.
3517If you intend to change the filter type during the course of writing
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3518the image, you should start with flags set for all of the filters
3519you intend to use so that libpng can initialize its internal
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3520structures appropriately for all of the filter types. (Note that this
3521means the first row must always be adaptively filtered, because libpng
3522currently does not allocate the filter buffers until png_write_row()
3523is called for the first time.)
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3524
3525 filters = PNG_FILTER_NONE | PNG_FILTER_SUB
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3526 PNG_FILTER_UP | PNG_FILTER_AVG |
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3527 PNG_FILTER_PAETH | PNG_ALL_FILTERS;
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3528
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3529 png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
3530 filters);
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3531 The second parameter can also be
3532 PNG_INTRAPIXEL_DIFFERENCING if you are
3533 writing a PNG to be embedded in a MNG
3534 datastream. This parameter must be the
3535 same as the value of filter_method used
3536 in png_set_IHDR().
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3537
3538It is also possible to influence how libpng chooses from among the
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3539available filters. This is done in one or both of two ways - by
3540telling it how important it is to keep the same filter for successive
3541rows, and by telling it the relative computational costs of the filters.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3542
3543 double weights[3] = {1.5, 1.3, 1.1},
3544 costs[PNG_FILTER_VALUE_LAST] =
3545 {1.0, 1.3, 1.3, 1.5, 1.7};
3546
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]3547 png_set_filter_heuristics(png_ptr,
3548 PNG_FILTER_HEURISTIC_WEIGHTED, 3,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3549 weights, costs);
3550
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3551The weights are multiplying factors that indicate to libpng that the
3552row filter should be the same for successive rows unless another row filter
3553is that many times better than the previous filter. In the above example,
3554if 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]3555"sum of absolute differences" 1.5 x 1.3 times higher than other filters
3556and still be chosen, while the NONE filter could have a sum 1.1 times
3557higher than other filters and still be chosen. Unspecified weights are
3558taken to be 1.0, and the specified weights should probably be declining
3559like those above in order to emphasize recent filters over older filters.
3560
3561The filter costs specify for each filter type a relative decoding cost
3562to be considered when selecting row filters. This means that filters
3563with higher costs are less likely to be chosen over filters with lower
3564costs, unless their "sum of absolute differences" is that much smaller.
3565The costs do not necessarily reflect the exact computational speeds of
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]3566the various filters, since this would unduly influence the final image
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3567size.
3568
3569Note that the numbers above were invented purely for this example and
3570are given only to help explain the function usage. Little testing has
3571been done to find optimum values for either the costs or the weights.
3572
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3573.SS Removing unwanted object code
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3574
3575There are a bunch of #define's in pngconf.h that control what parts of
3576libpng are compiled. All the defines end in _SUPPORTED. If you are
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3577never going to use a capability, you can change the #define to #undef
3578before recompiling libpng and save yourself code and data space, or
3579you can turn off individual capabilities with defines that begin with
3580PNG_NO_.
3581
3582You can also turn all of the transforms and ancillary chunk capabilities
Glenn Randers-Pehrson228bd392000-04-23 23:14:02 -0500[diff] [blame]3583off en masse with compiler directives that define
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3584PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
3585or all four,
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3586along with directives to turn on any of the capabilities that you do
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3587want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3588the extra transformations but still leave the library fully capable of reading
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3589and writing PNG files with all known public chunks
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3590Use of the PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3591produces a library that is incapable of reading or writing ancillary chunks.
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3592If you are not using the progressive reading capability, you can
Glenn Randers-Pehrsond0dce401998-05-09 10:02:29 -0500[diff] [blame]3593turn that off with PNG_NO_PROGRESSIVE_READ (don't confuse
Glenn Randers-Pehrson08a33431998-03-07 06:06:55 -0600[diff] [blame]3594this with the INTERLACING capability, which you'll still have).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3595
3596All the reading and writing specific code are in separate files, so the
3597linker should only grab the files it needs. However, if you want to
3598make sure, or if you are building a stand alone library, all the
3599reading files start with pngr and all the writing files start with
3600pngw. The files that don't match either (like png.c, pngtrans.c, etc.)
3601are used for both reading and writing, and always need to be included.
3602The progressive reader is in pngpread.c
3603
3604If you are creating or distributing a dynamically linked library (a .so
3605or DLL file), you should not remove or disable any parts of the library,
3606as this will cause applications linked with different versions of the
3607library to fail if they call functions not available in your library.
3608The size of the library itself should not be an issue, because only
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3609those sections that are actually used will be loaded into memory.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3610
Glenn Randers-Pehrson61c32d92000-02-04 23:40:16 -0600[diff] [blame]3611.SS Requesting debug printout
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3612
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3613The macro definition PNG_DEBUG can be used to request debugging
3614printout. Set it to an integer value in the range 0 to 3. Higher
3615numbers result in increasing amounts of debugging information. The
3616information is printed to the "stderr" file, unless another file
3617name is specified in the PNG_DEBUG_FILE macro definition.
3618
3619When PNG_DEBUG > 0, the following functions (macros) become available:
3620
3621 png_debug(level, message)
3622 png_debug1(level, message, p1)
3623 png_debug2(level, message, p1, p2)
3624
3625in which "level" is compared to PNG_DEBUG to decide whether to print
3626the message, "message" is the formatted string to be printed,
3627and p1 and p2 are parameters that are to be embedded in the string
3628according to printf-style formatting directives. For example,
3629
3630 png_debug1(2, "foo=%d\n", foo);
3631
3632is expanded to
3633
3634 if(PNG_DEBUG > 2)
3635 fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
3636
3637When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
3638can still use PNG_DEBUG to control your own debugging:
3639
3640 #ifdef PNG_DEBUG
3641 fprintf(stderr, ...
3642 #endif
3643
3644When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
3645having level = 0 will be printed. There aren't any such statements in
3646this version of libpng, but if you insert some they will be printed.
3647
Glenn Randers-Pehrson56f63962008-10-06 10:16:17 -0500[diff] [blame]3648.SH VI. MNG support
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]3649
3650The MNG specification (available at http://www.libpng.org/pub/mng) allows
3651certain extensions to PNG for PNG images that are embedded in MNG datastreams.
3652Libpng can support some of these extensions. To enable them, use the
3653png_permit_mng_features() function:
3654
3655 feature_set = png_permit_mng_features(png_ptr, mask)
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3656 mask is a png_uint_32 containing the bitwise OR of the
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]3657 features you want to enable. These include
3658 PNG_FLAG_MNG_EMPTY_PLTE
3659 PNG_FLAG_MNG_FILTER_64
3660 PNG_ALL_MNG_FEATURES
Glenn Randers-Pehrsonebd7f9a2006-10-19 09:37:56 -0500[diff] [blame]3661 feature_set is a png_uint_32 that is the bitwise AND of
Glenn Randers-Pehrson2ad31ae2000-12-15 08:54:42 -0600[diff] [blame]3662 your mask with the set of MNG features that is
3663 supported by the version of libpng that you are using.
3664
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3665It is an error to use this function when reading or writing a standalone
3666PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
Glenn Randers-Pehrsonf05f8032000-12-23 14:27:39 -0600[diff] [blame]3667in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
3668and the MHDR and MEND chunks. Libpng does not provide support for these
3669or any other MNG chunks; your application must provide its own support for
3670them. You may wish to consider using libmng (available at
3671http://www.libmng.com) instead.
Glenn Randers-Pehrson408b4212000-12-18 09:33:57 -0600[diff] [blame]3672
Glenn Randers-Pehrson8fb550c2009-03-21 08:15:32 -0500[diff] [blame]3673.SH VII. Changes to Libpng from version 0.88
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3674
3675It should be noted that versions of libpng later than 0.96 are not
3676distributed by the original libpng author, Guy Schalnat, nor by
3677Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
3678distributed versions 0.89 through 0.96, but rather by another member
3679of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
3680still alive and well, but they have moved on to other things.
3681
3682The old libpng functions png_read_init(), png_write_init(),
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]3683png_info_init(), png_read_destroy(), and png_write_destroy() have been
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]3684moved to PNG_INTERNAL in version 0.95 to discourage their use. These
3685functions will be removed from libpng version 2.0.0.
3686
3687The preferred method of creating and initializing the libpng structures is
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3688via the png_create_read_struct(), png_create_write_struct(), and
3689png_create_info_struct() because they isolate the size of the structures
3690from the application, allow version error checking, and also allow the
3691use of custom error handling routines during the initialization, which
3692the old functions do not. The functions png_read_destroy() and
3693png_write_destroy() do not actually free the memory that libpng
3694allocated for these structs, but just reset the data structures, so they
3695can be used instead of png_destroy_read_struct() and
3696png_destroy_write_struct() if you feel there is too much system overhead
3697allocating and freeing the png_struct for each image read.
3698
3699Setting the error callbacks via png_set_message_fn() before
3700png_read_init() as was suggested in libpng-0.88 is no longer supported
Glenn Randers-Pehrson5c6aeb21998-12-29 11:47:59 -0600[diff] [blame]3701because this caused applications that do not use custom error functions
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3702to fail if the png_ptr was not initialized to zero. It is still possible
3703to set the error callbacks AFTER png_read_init(), or to change them with
Glenn Randers-Pehrson75294572000-05-06 14:09:57 -0500[diff] [blame]3704png_set_error_fn(), which is essentially the same function, but with a new
3705name to force compilation errors with applications that try to use the old
3706method.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]3707
Glenn Randers-Pehrson1ef65b62000-05-12 06:19:53 -0500[diff] [blame]3708Starting with version 1.0.7, you can find out which version of the library
3709you are using at run-time:
3710
3711 png_uint_32 libpng_vn = png_access_version_number();
3712
3713The number libpng_vn is constructed from the major version, minor
3714version with leading zero, and release number with leading zero,
3715(e.g., libpng_vn for version 1.0.7 is 10007).
3716
3717You can also check which version of png.h you used when compiling your
3718application:
3719
3720 png_uint_32 application_vn = PNG_LIBPNG_VER;
3721
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3722.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]3723
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3724Support for user memory management was enabled by default. To
3725accomplish this, the functions png_create_read_struct_2(),
3726png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
3727png_malloc_default(), and png_free_default() were added.
3728
3729Support for certain MNG features was enabled.
3730
3731Support for numbered error messages was added. However, we never got
3732around to actually numbering the error messages. The function
3733png_set_strip_error_numbers() was added (Note: the prototype for this
3734function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
3735builds of libpng-1.2.15. It was restored in libpng-1.2.36).
3736
3737The png_malloc_warn() function was added at libpng-1.2.3. This issues
3738a png_warning and returns NULL instead of aborting when it fails to
3739acquire the requested memory allocation.
3740
3741Support for setting user limits on image width and height was enabled
3742by default. The functions png_set_user_limits(), png_get_user_width_max(),
3743and png_get_user_height_max() were added at libpng-1.2.6.
3744
3745The png_set_add_alpha() function was added at libpng-1.2.7.
3746
3747The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
3748Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
3749tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
3750deprecated.
3751
3752A number of macro definitions in support of runtime selection of
3753assembler code features (especially Intel MMX code support) were
3754added at libpng-1.2.0:
3755
3756 PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
3757 PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
3758 PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
3759 PNG_ASM_FLAG_MMX_READ_INTERLACE
3760 PNG_ASM_FLAG_MMX_READ_FILTER_SUB
3761 PNG_ASM_FLAG_MMX_READ_FILTER_UP
3762 PNG_ASM_FLAG_MMX_READ_FILTER_AVG
3763 PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
3764 PNG_ASM_FLAGS_INITIALIZED
3765 PNG_MMX_READ_FLAGS
3766 PNG_MMX_FLAGS
3767 PNG_MMX_WRITE_FLAGS
3768 PNG_MMX_FLAGS
3769
3770We added the following functions in support of runtime
3771selection of assembler code features:
3772
3773 png_get_mmx_flagmask()
3774 png_set_mmx_thresholds()
3775 png_get_asm_flags()
3776 png_get_mmx_bitdepth_threshold()
3777 png_get_mmx_rowbytes_threshold()
3778 png_set_asm_flags()
3779
3780We replaced all of these functions with simple stubs in libpng-1.2.20,
3781when the Intel assembler code was removed due to a licensing issue.
3782
3783.SH IX. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
3784
3785Private libpng prototypes and macro definitions were moved from
3786png.h and pngconf.h into a new pngpriv.h header file.
3787
3788Support for the iTXt chunk has been enabled by default.
3789
3790Support for global arrays was disabled by default.
3791
3792Some obsolete/deprecated macros and functions have been removed.
3793
3794The PNG_1_0_X and PNG_1_2_X macros were eliminated.
3795
3796Many WIN32_WCE #ifdefs were removed.
3797
3798PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
3799deprecated since libpng-1.0.16 and libpng-1.2.6.
3800
3801The function
3802 png_check_sig(sig, num)
3803was replaced with
3804 !png_sig_cmp(sig, 0, num)
3805It has been deprecated since libpng-0.90.
3806
3807The functions png_read_init(info_ptr), png_write_init(info_ptr),
3808png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
3809have been removed. They have been deprecated since libpng-0.95.
3810
3811The function
3812 png_set_gray_1_2_4_to_8()
3813which also expands tRNS to alpha was replaced with
3814 png_set_expand_gray_1_2_4_to_8()
3815which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
3816
3817Support for numbered error messages was removed by default, since we
3818never got around to actually numbering the error messages. The function
3819png_set_strip_error_numbers() was removed from the library by default.
3820
3821Functions png_set_benign_errors(), png_benign_error(), and
3822png_chunk_benign_error() were added.
3823
3824Support for setting the maximum amount of memory that the application
3825will allocate for reading chunks was added, as a security measure.
3826The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
3827were added to the library.
3828
3829We implemented support for I/O states. Added png_ptr member io_state, and
3830functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
3831
3832The png_permit_empty_plte() was removed. It has been deprecated
3833since libpng-1.0.9. Use png_permit_mng_features() instead.
3834
3835We removed the obsolete stub functions png_get_mmx_flagmask(),
3836png_set_mmx_thresholds(), png_get_asm_flags(),
3837png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
3838png_set_asm_flags(), and png_mmx_supported()
3839
3840We removed the png_memcpy_check() and png_memset_check() functions.
3841
3842We changed the prototype for png_malloc() from
3843 png_malloc(png_structp png_ptr, png_uint_32 size)
3844to
3845 png_malloc(png_structp png_ptr, png_alloc_size_t size)
3846
3847We changed the prototypes of png_get_compression_buffer_size() and
3848png_set_compression_buffer_size() to work with png_size_t instead of
3849png_uint_32.
3850
3851The png_zalloc() function no longer zeroes out the memory that it
3852allocates.
3853
3854The png_zalloc() and png_zfree() functions are no longer exported.
3855
3856The png_calloc() function was added.
3857
3858We removed the trailing '.' from the warning and error messages.
3859
Glenn Randers-Pehrson6a9c2ce2009-03-27 19:30:10 -0500[diff] [blame]3860
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3861.SH X. Detecting libpng
3862
3863The png_get_io_ptr() function has been present since libpng-0.88, has never
3864changed, and is unaffected by conditional compilation macros. It is the
3865best choice for use in configure scripts for detecting the presence of any
3866libpng version since 0.88.
3867
3868.SH XI. Source code repository
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3869
3870Since about February 2009, version 1.2.34, libpng has been under "git" source
3871control. The git repository was built from old libpng-x.y.z.tar.gz files
3872going back to version 0.70. You can access the git repository (read only)
3873at
3874
3875 git://libpng.git.sourceforge.net/gitroot/libpng
3876
3877or you can browse it via "gitweb" at
3878
3879 http://libpng.git.sourceforge.net/git/gitweb.cgi?p=libpng
3880
3881Patches can be sent to glennrp at users.sourceforge.net or to
3882png-mng-implement at lists.sourceforge.net or you can upload them to
3883the libpng bug tracker at
3884
3885 http://libpng.sourceforge.net
3886
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3887.SH XII. Coding style
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3888
3889Our coding style is similar to the "Allman" style, with curly
3890braces on separate lines:
3891
3892 if (condition)
3893 {
3894 action;
3895 }
3896
3897 else if (another condition)
3898 {
3899 another action;
3900 }
3901
3902The braces can be omitted from simple one-line actions:
3903
3904 if (condition)
3905 return (0);
3906
3907We use 3-space indentation, except for continued statements which
3908are usually indented the same as the first line of the statement
3909plus four more spaces.
3910
3911Comments appear with the leading "/*" at the same indentation as
3912the statement that follows the comment:
3913
3914 /* Single-line comment */
3915 statement;
3916
3917 /* Multiple-line
3918 * comment
3919 */
3920 statement;
3921
3922Very short comments can be placed at the end of the statement
3923to which they pertain:
3924
3925 statement; /* comment */
3926
3927We don't use C++ style ("//") comments. We have, however,
3928used them in the past in some now-abandoned MMX assembler
3929code.
3930
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]3931Functions and their curly braces are not indented, and
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3932exported functions are marked with PNGAPI:
3933
3934 /* This is a public function that is visible to
3935 * application programers. It does thus-and-so.
3936 */
3937 void PNGAPI
3938 png_exported_function(png_ptr, png_info, foo)
3939 {
3940 body;
3941 }
3942
3943The prototypes for all exported functions appear in png.h.
3944
3945We mark all non-exported functions with "/* PRIVATE */"":
3946
3947 void /* PRIVATE */
3948 png_non_exported_function(png_ptr, png_info, foo)
3949 {
3950 body;
3951 }
3952
3953The prototypes for non-exported functions can appear in
3954pngpriv.h or in the file where the function is located.
3955
3956The names of all exported functions and variables begin
3957with "png_", and all publicly visible C preprocessor
3958macros begin with "PNG_".
3959
3960We put a space after each comma and after each semicolon
3961in "for" statments, and we put spaces before and after each
3962C binary operator and after "for" or "while". We don't
3963put a space between a typecast and the expression being
3964cast, nor do we put one between a function name and the
3965left parenthesis that follows it:
3966
3967 for (i = 2; i > 0; --i)
3968 x[i] = a(x) + (int)b;
3969
3970Other rules can be inferred by inspecting the libpng
3971source.
3972
Glenn Randers-Pehrson424c9852009-06-02 13:45:15 -0500[diff] [blame]3973.SH XIII. Y2K Compliance in libpng
Glenn Randers-Pehrson76546822009-05-16 07:25:42 -0500[diff] [blame]3974
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]3975June 8, 2009
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]3976
3977Since the PNG Development group is an ad-hoc body, we can't make
3978an official declaration.
3979
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3980This is your unofficial assurance that libpng from version 0.71 and
Glenn Randers-Pehrson7aa18342009-06-05 17:24:17 -0500[diff] [blame]3981upward through 1.4.0beta63 are Y2K compliant. It is my belief that earlier
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]3982versions were also Y2K compliant.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]3983
3984Libpng only has three year fields. One is a 2-byte unsigned integer that
3985will hold years up to 65535. The other two hold the date in text
3986format, and will hold years up to 9999.
3987
3988The integer is
3989 "png_uint_16 year" in png_time_struct.
3990
3991The strings are
3992 "png_charp time_buffer" in png_struct and
3993 "near_time_buffer", which is a local character string in png.c.
3994
3995There are seven time-related functions:
3996
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]3997 png_convert_to_rfc_1123() in png.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]3998 (formerly png_convert_to_rfc_1152() in error)
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]3999 png_convert_from_struct_tm() in pngwrite.c, called
4000 in pngwrite.c
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4001 png_convert_from_time_t() in pngwrite.c
4002 png_get_tIME() in pngget.c
4003 png_handle_tIME() in pngrutil.c, called in pngread.c
4004 png_set_tIME() in pngset.c
4005 png_write_tIME() in pngwutil.c, called in pngwrite.c
4006
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4007All appear to handle dates properly in a Y2K environment. The
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4008png_convert_from_time_t() function calls gmtime() to convert from system
4009clock time, which returns (year - 1900), which we properly convert to
4010the full 4-digit year. There is a possibility that applications using
4011libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4012function, or that they are incorrectly passing only a 2-digit year
4013instead of "year - 1900" into the png_convert_from_struct_tm() function,
4014but this is not under our control. The libpng documentation has always
4015stated that it works with 4-digit years, and the APIs have been
4016documented as such.
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4017
4018The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
4019integer to hold the year, and can hold years as large as 65535.
4020
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4021zlib, upon which libpng depends, is also Y2K compliant. It contains
4022no date-related code.
4023
Glenn Randers-Pehrson87544ac1999-01-13 22:06:39 -0600[diff] [blame]4024
4025 Glenn Randers-Pehrson
4026 libpng maintainer
4027 PNG Development Group
4028
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4029.SH NOTE
4030
4031Note about libpng version numbers:
4032
4033Due to various miscommunications, unforeseen code incompatibilities
4034and occasional factors outside the authors' control, version numbering
4035on the library has not always been consistent and straightforward.
4036The following table summarizes matters since version 0.89c, which was
4037the first widely used release:
4038
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4039 source png.h png.h shared-lib
4040 version string int version
4041 ------- ------ ----- ----------
4042 0.89c ("beta 3") 0.89 89 1.0.89
4043 0.90 ("beta 4") 0.90 90 0.90
4044 0.95 ("beta 5") 0.95 95 0.95
4045 0.96 ("beta 6") 0.96 96 0.96
4046 0.97b ("beta 7") 1.00.97 97 1.0.1
4047 0.97c 0.97 97 2.0.97
4048 0.98 0.98 98 2.0.98
4049 0.99 0.99 98 2.0.99
4050 0.99a-m 0.99 99 2.0.99
4051 1.00 1.00 100 2.1.0
4052 1.0.0 1.0.0 100 2.1.0
4053 1.0.0 (from here on, the 100 2.1.0
4054 1.0.1 png.h string is 10001 2.1.0
4055 1.0.1a-e identical to the 10002 from here on, the
4056 1.0.2 source version) 10002 shared library is 2.V
4057 1.0.2a-b 10003 where V is the source
4058 1.0.1 10001 code version except as
4059 1.0.1a-e 10002 2.1.0.1a-e noted.
4060 1.0.2 10002 2.1.0.2
4061 1.0.2a-b 10003 2.1.0.2a-b
4062 1.0.3 10003 2.1.0.3
4063 1.0.3a-d 10004 2.1.0.3a-d
4064 1.0.4 10004 2.1.0.4
4065 1.0.4a-f 10005 2.1.0.4a-f
4066 1.0.5 (+ 2 patches) 10005 2.1.0.5
4067 1.0.5a-d 10006 2.1.0.5a-d
4068 1.0.5e-r 10100 2.1.0.5e-r
4069 1.0.5s-v 10006 2.1.0.5s-v
4070 1.0.6 (+ 3 patches) 10006 2.1.0.6
4071 1.0.6d-g 10007 2.1.0.6d-g
4072 1.0.6h 10007 10.6h
4073 1.0.6i 10007 10.6i
4074 1.0.6j 10007 2.1.0.6j
4075 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14
4076 1.0.7beta15-18 1 10007 2.1.0.7beta15-18
4077 1.0.7rc1-2 1 10007 2.1.0.7rc1-2
4078 1.0.7 1 10007 2.1.0.7
4079 1.0.8beta1-4 1 10008 2.1.0.8beta1-4
4080 1.0.8rc1 1 10008 2.1.0.8rc1
4081 1.0.8 1 10008 2.1.0.8
4082 1.0.9beta1-6 1 10009 2.1.0.9beta1-6
4083 1.0.9rc1 1 10009 2.1.0.9rc1
4084 1.0.9beta7-10 1 10009 2.1.0.9beta7-10
4085 1.0.9rc2 1 10009 2.1.0.9rc2
4086 1.0.9 1 10009 2.1.0.9
Glenn Randers-Pehrsone1644472001-03-23 05:06:56 -0600[diff] [blame]4087 1.0.10beta1 1 10010 2.1.0.10beta1
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4088 1.0.10rc1 1 10010 2.1.0.10rc1
Glenn Randers-Pehrson13cfbac2001-03-30 06:42:28 -0600[diff] [blame]4089 1.0.10 1 10010 2.1.0.10
Glenn Randers-Pehrsone1eff582001-04-14 20:15:41 -0500[diff] [blame]4090 1.0.11beta1-3 1 10011 2.1.0.11beta1-3
Glenn Randers-Pehrson82ae3832001-04-20 10:32:10 -0500[diff] [blame]4091 1.0.11rc1 1 10011 2.1.0.11rc1
Glenn Randers-Pehrson32835392001-04-27 08:29:32 -0500[diff] [blame]4092 1.0.11 1 10011 2.1.0.11
Glenn Randers-Pehrsonb1828932001-06-23 08:03:17 -0500[diff] [blame]4093 1.0.12beta1-2 2 10012 2.1.0.12beta1-2
4094 1.0.12rc1 2 10012 2.1.0.12rc1
4095 1.0.12 2 10012 2.1.0.12
4096 1.1.0a-f - 10100 2.1.1.0a-f abandoned
Glenn Randers-Pehrson8b6a8892001-05-18 04:54:50 -0500[diff] [blame]4097 1.2.0beta1-2 2 10200 2.1.2.0beta1-2
Glenn Randers-Pehrson5a0be342001-10-18 20:55:13 -0500[diff] [blame]4098 1.2.0beta3-5 3 10200 3.1.2.0beta3-5
4099 1.2.0rc1 3 10200 3.1.2.0rc1
4100 1.2.0 3 10200 3.1.2.0
Glenn Randers-Pehrson5cded0b2001-11-07 07:10:08 -0600[diff] [blame]4101 1.2.1beta-4 3 10201 3.1.2.1beta1-4
Glenn Randers-Pehrsondb3b88d2001-12-04 06:30:43 -0600[diff] [blame]4102 1.2.1rc1-2 3 10201 3.1.2.1rc1-2
4103 1.2.1 3 10201 3.1.2.1
Glenn Randers-Pehrson25228ab2002-03-31 07:33:55 -0600[diff] [blame]4104 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6
Glenn Randers-Pehrsonfcbd7872002-04-07 16:35:38 -0500[diff] [blame]4105 1.0.13beta1 10 10013 10.so.0.1.0.13beta1
4106 1.0.13rc1 10 10013 10.so.0.1.0.13rc1
4107 1.2.2rc1 12 10202 12.so.0.1.2.2rc1
Glenn Randers-Pehrson4fb046a2002-04-15 09:25:51 -0500[diff] [blame]4108 1.0.13 10 10013 10.so.0.1.0.13
4109 1.2.2 12 10202 12.so.0.1.2.2
Glenn Randers-Pehrson22f28962002-05-13 18:17:09 -0500[diff] [blame]4110 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6
4111 1.2.3 12 10203 12.so.0.1.2.3
Glenn Randers-Pehrsond020e9d2002-06-28 09:34:00 -0500[diff] [blame]4112 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3
Glenn Randers-Pehrson2ae022d2002-07-01 22:23:46 -0500[diff] [blame]4113 1.2.4rc1 13 10204 12.so.0.1.2.4rc1
Glenn Randers-Pehrson484a8a12002-07-07 19:15:20 -0500[diff] [blame]4114 1.0.14 10 10014 10.so.0.1.0.14
4115 1.2.4 13 10204 12.so.0.1.2.4
Glenn Randers-Pehrson5b5dcf82004-07-17 22:45:44 -0500[diff] [blame]4116 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2
4117 1.0.15rc1 10 10015 10.so.0.1.0.15rc1
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4118 1.0.15 10 10015 10.so.0.1.0.15
4119 1.2.5 13 10205 12.so.0.1.2.5
4120 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4
Glenn Randers-Pehrson37f116a2004-08-15 07:15:39 -0500[diff] [blame]4121 1.2.6rc1-5 13 10206 12.so.0.1.2.6rc1-5
4122 1.0.16 10 10016 10.so.0.1.0.16
4123 1.2.6 13 10206 12.so.0.1.2.6
Glenn Randers-Pehrson67864af2004-08-28 23:30:07 -0500[diff] [blame]4124 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2
Glenn Randers-Pehrson5b779162004-09-04 13:25:08 -0500[diff] [blame]4125 1.0.17rc1 10 10017 12.so.0.1.0.17rc1
4126 1.2.7rc1 13 10207 12.so.0.1.2.7rc1
Glenn Randers-Pehrson250dfe12004-09-11 21:19:54 -0500[diff] [blame]4127 1.0.17 10 10017 12.so.0.1.0.17
4128 1.2.7 13 10207 12.so.0.1.2.7
Glenn Randers-Pehrson40936072004-11-20 11:18:40 -0600[diff] [blame]4129 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5
Glenn Randers-Pehrson584b96e2004-11-29 15:08:00 -0600[diff] [blame]4130 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5
4131 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5
Glenn Randers-Pehrson917648e2004-12-02 18:14:51 -0600[diff] [blame]4132 1.0.18 10 10018 12.so.0.1.0.18
4133 1.2.8 13 10208 12.so.0.1.2.8
Glenn Randers-Pehrsone6474622006-03-04 16:50:47 -0600[diff] [blame]4134 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3
Glenn Randers-Pehrson4deeb792006-03-22 16:21:59 -0600[diff] [blame]4135 1.2.9beta4-11 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrson3a512032006-03-31 05:29:33 -0600[diff] [blame]4136 1.2.9rc1 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsona7d0c942006-04-14 06:22:52 -0500[diff] [blame]4137 1.2.9 13 10209 12.so.0.9[.0]
Glenn Randers-Pehrsond60b8fa2006-04-20 21:31:14 -0500[diff] [blame]4138 1.2.10beta1-7 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson17218292006-04-20 07:20:46 -0500[diff] [blame]4139 1.2.10rc1-2 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson86dc9812006-05-10 07:27:44 -0500[diff] [blame]4140 1.2.10 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson6bc53be2006-06-16 07:52:03 -0500[diff] [blame]4141 1.4.0beta1-6 14 10400 14.so.0.0[.0]
4142 1.2.11beta1-4 13 10210 12.so.0.10[.0]
Glenn Randers-Pehrson3424ee72006-07-12 13:33:47 -0500[diff] [blame]4143 1.4.0beta7-8 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrson701dbaa2006-11-17 09:36:54 -0600[diff] [blame]4144 1.2.11 13 10211 12.so.0.11[.0]
4145 1.2.12 13 10212 12.so.0.12[.0]
4146 1.4.0beta9-14 14 10400 14.so.0.0[.0]
4147 1.2.13 13 10213 12.so.0.13[.0]
Glenn Randers-Pehrson97a9b482008-10-25 20:03:28 -0500[diff] [blame]4148 1.4.0beta15-36 14 10400 14.so.0.0[.0]
Glenn Randers-Pehrson7aa18342009-06-05 17:24:17 -0500[diff] [blame]4149 1.4.0beta37-63 14 10400 14.so.14.0[.0]
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4150
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4151Henceforth the source version will match the shared-library minor
4152and patch numbers; the shared-library major version number will be
4153used for changes in backward compatibility, as it is intended. The
4154PNG_PNGLIB_VER macro, which is not used within libpng but is available
4155for applications, is an unsigned integer of the form xyyzz corresponding
4156to 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]4157were given the previous public release number plus a letter, until
4158version 1.0.6j; from then on they were given the upcoming public
4159release number plus "betaNN" or "rcN".
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4160
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4161.SH "SEE ALSO"
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4162libpngpf(3), png(5)
4163.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4164.IR libpng :
4165.IP
Glenn Randers-Pehrsona4981d42004-08-25 22:00:45 -0500[diff] [blame]4166http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]4167http://www.libpng.org/pub/png
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4168
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4169.LP
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4170.IR zlib :
4171.IP
4172(generally) at the same location as
4173.I libpng
4174or at
4175.br
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]4176ftp://ftp.info-zip.org/pub/infozip/zlib
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4177
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4178.LP
4179.IR PNG specification: RFC 2083
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4180.IP
4181(generally) at the same location as
4182.I libpng
4183or at
4184.br
4185ftp://ds.internic.net/rfc/rfc2083.txt
4186.br
4187or (as a W3C Recommendation) at
4188.br
4189http://www.w3.org/TR/REC-png.html
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4190
Glenn Randers-Pehrsoncbe52d81998-02-28 07:00:24 -0600[diff] [blame]4191.LP
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4192In the case of any inconsistency between the PNG specification
4193and this library, the specification takes precedence.
4194
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4195.SH AUTHORS
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4196This man page: Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]4197<glennrp at users.sourceforge.net>
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4198
4199The contributing authors would like to thank all those who helped
4200with testing, bug fixes, and patience. This wouldn't have been
4201possible without all of you.
4202
4203Thanks to Frank J. T. Wojcik for helping with the documentation.
Glenn Randers-Pehrson166c5a31999-12-10 09:43:02 -0600[diff] [blame]4204
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]4205Libpng version 1.4.0beta63 - June 8, 2009:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4206Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]4207Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4208
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4209Supported by the PNG development group
4210.br
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]4211png-mng-implement at lists.sf.net
4212(subscription required; visit
Glenn Randers-Pehrson7b34df32006-02-24 06:30:16 -0600[diff] [blame]4213png-mng-implement at lists.sourceforge.net (subscription required; visit
Glenn Randers-Pehrson9c3ab682006-02-20 22:09:05 -0600[diff] [blame]4214https://lists.sourceforge.net/lists/listinfo/png-mng-implement
4215to subscribe).
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4216
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4217.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4218
Glenn Randers-Pehrson5e5c1e12000-11-10 12:26:19 -0600[diff] [blame]4219(This copy of the libpng notices is provided for your convenience. In case of
4220any discrepancy between this copy and the notices in the file png.h that is
4221included in the libpng distribution, the latter shall prevail.)
4222
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4223If you modify libpng you may insert additional notices immediately following
4224this sentence.
4225
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]4226libpng versions 1.2.6, August 15, 2004, through 1.4.0beta63, June 8, 2009, are
Glenn Randers-Pehrsona7dbcba2007-05-15 16:16:34 -0500[diff] [blame]4227Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4228distributed according to the same disclaimer and license as libpng-1.2.5
Glenn Randers-Pehrsond029a752004-08-09 21:50:32 -0500[diff] [blame]4229with the following individual added to the list of Contributing Authors
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4230
4231 Cosmin Truta
Glenn Randers-Pehrson5fea36f2004-07-28 08:20:44 -0500[diff] [blame]4232
4233libpng 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]4234Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
Glenn Randers-Pehrson32fc5ce2000-07-24 06:34:14 -0500[diff] [blame]4235distributed according to the same disclaimer and license as libpng-1.0.6
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4236with the following individuals added to the list of Contributing Authors
4237
4238 Simon-Pierre Cadieux
4239 Eric S. Raymond
4240 Gilles Vollant
4241
4242and with the following additions to the disclaimer:
4243
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]4244 There is no warranty against interference with your
4245 enjoyment of the library or against infringement.
4246 There is no warranty that our efforts or the library
4247 will fulfill any of your particular purposes or needs.
4248 This library is provided with all faults, and the entire
4249 risk of satisfactory quality, performance, accuracy, and
4250 effort is with the user.
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4251
4252libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
4253Copyright (c) 1998, 1999 Glenn Randers-Pehrson
4254Distributed according to the same disclaimer and license as libpng-0.96,
4255with the following individuals added to the list of Contributing Authors:
4256
4257 Tom Lane
4258 Glenn Randers-Pehrson
4259 Willem van Schaik
4260
4261libpng versions 0.89, June 1996, through 0.96, May 1997, are
Glenn Randers-Pehrson54a066a1999-09-19 06:04:18 -0500[diff] [blame]4262Copyright (c) 1996, 1997 Andreas Dilger
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4263Distributed according to the same disclaimer and license as libpng-0.88,
4264with the following individuals added to the list of Contributing Authors:
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4265
4266 John Bowler
4267 Kevin Bracey
4268 Sam Bushell
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4269 Magnus Holmgren
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4270 Greg Roelofs
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4271 Tom Tanner
4272
4273libpng versions 0.5, May 1995, through 0.88, January 1996, are
4274Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
4275
4276For the purposes of this copyright and license, "Contributing Authors"
4277is defined as the following set of individuals:
4278
4279 Andreas Dilger
4280 Dave Martindale
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4281 Guy Eric Schalnat
4282 Paul Schmidt
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4283 Tim Wegner
Glenn Randers-Pehrsonc9442291999-01-06 21:50:16 -0600[diff] [blame]4284
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4285The PNG Reference Library is supplied "AS IS". The Contributing Authors
4286and Group 42, Inc. disclaim all warranties, expressed or implied,
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4287including, without limitation, the warranties of merchantability and of
4288fitness for any purpose. The Contributing Authors and Group 42, Inc.
4289assume no liability for direct, indirect, incidental, special, exemplary,
4290or consequential damages, which may result from the use of the PNG
4291Reference Library, even if advised of the possibility of such damage.
Glenn Randers-Pehrsona357b991998-02-08 20:56:40 -0600[diff] [blame]4292
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4293Permission is hereby granted to use, copy, modify, and distribute this
4294source code, or portions hereof, for any purpose, without fee, subject
4295to the following restrictions:
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4296
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]42971. The origin of this source code must not be misrepresented.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4298
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]42992. Altered versions must be plainly marked as such and
4300 must not be misrepresented as being the original source.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4301
Glenn Randers-Pehrson19095602001-03-14 07:08:39 -0600[diff] [blame]43023. This Copyright notice may not be removed or altered from
4303 any source or altered source distribution.
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4304
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4305The Contributing Authors and Group 42, Inc. specifically permit, without
4306fee, and encourage the use of this source code as a component to
4307supporting the PNG file format in commercial products. If you use this
4308source code in a product, acknowledgment is not required but would be
4309appreciated.
4310
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4311
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4312A "png_get_copyright" function is available, for convenient use in "about"
4313boxes and the like:
4314
4315 printf("%s",png_get_copyright(NULL));
4316
4317Also, the PNG logo (in PNG format, of course) is supplied in the
Glenn Randers-Pehrsona4d54bd2000-07-14 08:15:12 -0500[diff] [blame]4318files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Glenn Randers-Pehrson4393a9a1999-09-17 12:27:26 -0500[diff] [blame]4319
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4320Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
Glenn Randers-Pehrsonbcfd15d1999-10-01 14:22:25 -0500[diff] [blame]4321certification mark of the Open Source Initiative.
4322
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4323Glenn Randers-Pehrson
Glenn Randers-Pehrson5dd2b8e2004-11-24 07:50:16 -0600[diff] [blame]4324glennrp at users.sourceforge.net
Glenn Randers-Pehrsonb5444a12009-06-08 08:36:19 -0500[diff] [blame^]4325June 8, 2009
Glenn Randers-Pehrson3d5a5202000-07-01 15:37:28 -0500[diff] [blame]4326
Glenn Randers-Pehrson0f881d61998-02-07 10:20:57 -0600[diff] [blame]4327.\" end of man page
4328