/* png.h - header file for PNG reference library * * libpng version 1 . 6 . 58 * * Copyright ( c ) 2018 - 2026 Cosmin Truta * Copyright ( c ) 1998 - 2002 , 2004 , 2006 - 2018 Glenn Randers - Pehrson * Copyright ( c ) 1996 - 1997 Andreas Dilger * Copyright ( c ) 1995 - 1996 Guy Eric Schalnat , Group 42 , Inc . * * This code is released under the libpng license . ( See LICENSE , below . ) * * Authors and maintainers : * libpng versions 0 . 71 , May 1995 , through 0 . 88 , January 1996 : Guy Schalnat * libpng versions 0 . 89 , June 1996 , through 0 . 96 , May 1997 : Andreas Dilger * libpng versions 0 . 97 , January 1998 , through 1 . 6 . 35 , July 2018 : * Glenn Randers - Pehrson * libpng versions 1 . 6 . 36 , December 2018 , through 1 . 6 . 58 , April 2026 : * Cosmin Truta * See also " Contributing Authors " , below . /* * COPYRIGHT NOTICE , DISCLAIMER , and LICENSE * = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = * * PNG Reference Library License version 2 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * * * Copyright ( c ) 1995 - 2026 The PNG Reference Library Authors . * * Copyright ( c ) 2018 - 2026 Cosmin Truta . * * Copyright ( c ) 2000 - 2002 , 2004 , 2006 - 2018 Glenn Randers - Pehrson . * * Copyright ( c ) 1996 - 1997 Andreas Dilger . * * Copyright ( c ) 1995 - 1996 Guy Eric Schalnat , Group 42 , Inc . * * The software is supplied " as is " , without warranty of any kind , * express or implied , including , without limitation , the warranties * of merchantability , fitness for a particular purpose , title , and * non - infringement . In no event shall the Copyright owners , or * anyone distributing the software , be liable for any damages or * other liability , whether in contract , tort or otherwise , arising * from , out of , or in connection with the software , or the use or * other dealings in the software , even if advised of the possibility * of such damage . * * Permission is hereby granted to use , copy , modify , and distribute * this software , or portions hereof , for any purpose , without fee , * subject to the following restrictions : * * 1 . The origin of this software must not be misrepresented ; you * must not claim that you wrote the original software . If you * use this software in a product , an acknowledgment in the product * documentation would be appreciated , but is not required . * * 2 . Altered source versions must be plainly marked as such , and must * not be misrepresented as being the original software . * * 3 . This Copyright notice may not be removed or altered from any * source or altered source distribution . * * * PNG Reference Library License version 1 ( for libpng 0 . 5 through 1 . 6 . 35 ) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * * libpng versions 1 . 0 . 7 , July 1 , 2000 , through 1 . 6 . 35 , July 15 , 2018 are * Copyright ( c ) 2000 - 2002 , 2004 , 2006 - 2018 Glenn Randers - Pehrson , are * derived from libpng - 1 . 0 . 6 , and are distributed according to the same * disclaimer and license as libpng - 1 . 0 . 6 with the following individuals * added to the list of Contributing Authors : * * Simon - Pierre Cadieux * Eric S . Raymond * Mans Rullgard * Cosmin Truta * Gilles Vollant * James Yu * Mandar Sahastrabuddhe * Google Inc . * Vadim Barkov * * and with the following additions to the disclaimer : * * There is no warranty against interference with your enjoyment of * the library or against infringement . There is no warranty that our * efforts or the library will fulfill any of your particular purposes * or needs . This library is provided with all faults , and the entire * risk of satisfactory quality , performance , accuracy , and effort is * with the user . * * Some files in the " contrib " directory and some configure - generated * files that are distributed with libpng have other copyright owners , and * are released under other open source licenses . * * libpng versions 0 . 97 , January 1998 , through 1 . 0 . 6 , March 20 , 2000 , are * Copyright ( c ) 1998 - 2000 Glenn Randers - Pehrson , are derived from * libpng - 0 . 96 , and are distributed according to the same disclaimer and * license as libpng - 0 . 96 , with the following individuals added to the * list of Contributing Authors : * * Tom Lane * Glenn Randers - Pehrson * Willem van Schaik * * libpng versions 0 . 89 , June 1996 , through 0 . 96 , May 1997 , are * Copyright ( c ) 1996 - 1997 Andreas Dilger , are derived from libpng - 0 . 88 , * and are distributed according to the same disclaimer and license as * libpng - 0 . 88 , with the following individuals added to the list of * Contributing Authors : * * John Bowler * Kevin Bracey * Sam Bushell * Magnus Holmgren * Greg Roelofs * Tom Tanner * * Some files in the " scripts " directory have other copyright owners , * but are released under this license . * * libpng versions 0 . 5 , May 1995 , through 0 . 88 , January 1996 , are * Copyright ( c ) 1995 - 1996 Guy Eric Schalnat , Group 42 , Inc . * * For the purposes of this copyright and license , " Contributing Authors " * is defined as the following set of individuals : * * Andreas Dilger * Dave Martindale * Guy Eric Schalnat * Paul Schmidt * Tim Wegner * * The PNG Reference Library is supplied " AS IS " . The Contributing * Authors and Group 42 , Inc . disclaim all warranties , expressed or * implied , including , without limitation , the warranties of * merchantability and of fitness for any purpose . The Contributing * Authors and Group 42 , Inc . assume no liability for direct , indirect , * incidental , special , exemplary , or consequential damages , which may * result from the use of the PNG Reference Library , even if advised of * the possibility of such damage . * * Permission is hereby granted to use , copy , modify , and distribute this * source code , or portions hereof , for any purpose , without fee , subject * to the following restrictions : * * 1 . The origin of this source code must not be misrepresented . * * 2 . Altered versions must be plainly marked as such and must not * be misrepresented as being the original source . * * 3 . This Copyright notice may not be removed or altered from any * source or altered source distribution . * * The Contributing Authors and Group 42 , Inc . specifically permit , * without fee , and encourage the use of this source code as a component * to supporting the PNG file format in commercial products . If you use * this source code in a product , acknowledgment is not required but would * be appreciated . * * END OF COPYRIGHT NOTICE , DISCLAIMER , and LICENSE . * * TRADEMARK * = = = = = = = = = * * The name " libpng " has not been registered by the Copyright owners * as a trademark in any jurisdiction . However , because libpng has * been distributed and maintained world - wide , continually since 1995 , * the Copyright owners claim " common - law trademark protection " in any * jurisdiction where common - law trademark is recognized . /* * A " png_get_copyright " function is available , for convenient use in " about " * boxes and the like : * * printf ( " % s " , png_get_copyright ( NULL ) ) ; * * Also , the PNG logo ( in PNG format , of course ) is supplied in the * files " pngbar . png " and " pngbar . jpg ( 88 x31 ) and " pngnow . png " ( 98 x31 ) . /* * The contributing authors would like to thank all those who helped * with testing , bug fixes , and patience . This wouldn ' t have been * possible without all of you . * * Thanks to Frank J . T . Wojcik for helping with the documentation . /* Note about libpng version numbers: * * Due to various miscommunications , unforeseen code incompatibilities * and occasional factors outside the authors ' control , version numbering * on the library has not always been consistent and straightforward . * The following table summarizes matters since version 0 . 89 c , which was * the first widely used release : * * source png . h png . h shared - lib * version string int version * - - - - - - - - - - - - - - - - - - - - - - - - - - - - * 0 . 89 c " 1 . 0 beta 3 " 0 . 89 89 1 . 0 . 89 * 0 . 90 " 1 . 0 beta 4 " 0 . 90 90 0 . 90 [ should have been 2 . 0 . 90 ] * 0 . 95 " 1 . 0 beta 5 " 0 . 95 95 0 . 95 [ should have been 2 . 0 . 95 ] * 0 . 96 " 1 . 0 beta 6 " 0 . 96 96 0 . 96 [ should have been 2 . 0 . 96 ] * 0 . 97 b " 1 . 00 . 97 beta 7 " 1 . 00 . 97 97 1 . 0 . 1 [ should have been 2 . 0 . 97 ] * 0 . 97 c 0 . 97 97 2 . 0 . 97 * 0 . 98 0 . 98 98 2 . 0 . 98 * 0 . 99 0 . 99 98 2 . 0 . 99 * 0 . 99 a - m 0 . 99 99 2 . 0 . 99 * 1 . 00 1 . 00 100 2 . 1 . 0 [ 100 should be 10000 ] * 1 . 0 . 0 ( from here on , the 100 2 . 1 . 0 [ 100 should be 10000 ] * 1 . 0 . 1 png . h string is 10001 2 . 1 . 0 * 1 . 0 . 1 a - e identical to the 10002 from here on , the shared library * 1 . 0 . 2 source version ) 10002 is 2 . V where V is the source code * 1 . 0 . 2 a - b 10003 version , except as noted . * 1 . 0 . 3 10003 * 1 . 0 . 3 a - d 10004 * 1 . 0 . 4 10004 * 1 . 0 . 4 a - f 10005 * 1 . 0 . 5 ( + 2 patches ) 10005 * 1 . 0 . 5 a - d 10006 * 1 . 0 . 5 e - r 10100 ( not source compatible ) * 1 . 0 . 5 s - v 10006 ( not binary compatible ) * 1 . 0 . 6 ( + 3 patches ) 10006 ( still binary incompatible ) * 1 . 0 . 6 d - f 10007 ( still binary incompatible ) * 1 . 0 . 6 g 10007 * 1 . 0 . 6 h 10007 10 . 6 h ( testing xy . z so - numbering ) * 1 . 0 . 6 i 10007 10 . 6 i * 1 . 0 . 6 j 10007 2 . 1 . 0 . 6 j ( incompatible with 1 . 0 . 0 ) * 1 . 0 . 7 beta11 - 14 DLLNUM 10007 2 . 1 . 0 . 7 beta11 - 14 ( binary compatible ) * 1 . 0 . 7 beta15 - 18 1 10007 2 . 1 . 0 . 7 beta15 - 18 ( binary compatible ) * 1 . 0 . 7 rc1 - 2 1 10007 2 . 1 . 0 . 7 rc1 - 2 ( binary compatible ) * 1 . 0 . 7 1 10007 ( still compatible ) * . . . * 1 . 0 . 69 10 10069 10 . so . 0 . 69 [ . 0 ] * . . . * 1 . 2 . 59 13 10259 12 . so . 0 . 59 [ . 0 ] * . . . * 1 . 4 . 20 14 10420 14 . so . 0 . 20 [ . 0 ] * . . . * 1 . 5 . 30 15 10530 15 . so . 15 . 30 [ . 0 ] * . . . * 1 . 6 . 58 16 10658 16 . so . 16 . 58 [ . 0 ] * * Henceforth the source version will match the shared - library major and * minor numbers ; the shared - library major version number will be used for * changes in backward compatibility , as it is intended . * The PNG_LIBPNG_VER macro , which is not used within libpng but is * available for applications , is an unsigned integer of the form XYYZZ * corresponding to the source version X . Y . Z ( leading zeros in Y and Z ) . * Beta versions were given the previous public release number plus a * letter , until version 1 . 0 . 6 j ; from then on they were given the upcoming * public release number plus " betaNN " or " rcNN " . * * Binary incompatibility exists only when applications make direct access * to the info_ptr or png_ptr members through png . h , and the compiled * application is loaded with a different version of the library . * * See libpng . txt or libpng . 3 for more information . The PNG specification * is available as a W3C Recommendation and as an ISO / IEC Standard ; see * < https : //www.w3.org/TR/2003/REC-PNG-20031110/> #ifndef PNG_H#define PNG_H/* This is not the place to learn how to use libpng. The file libpng-manual.txt * describes how to use libpng , and the file example . c summarizes it * with some code on which to build . This file is useful for looking * at the actual function definitions and structure components . If that * file has been stripped from your copy of libpng , you can find it at * < http : //www.libpng.org/pub/png/libpng-manual.txt> * * If you just need to read a PNG file and don ' t want to read the documentation * skip to the end of this file and read the section entitled ' simplified API ' . /* Version information for png.h - this should match the version in png.c */ #define PNG_LIBPNG_VER_STRING "1.6.58" #define PNG_HEADER_VERSION_STRING " libpng version " PNG_LIBPNG_VER_STRING "\n" /* The versions of shared library builds should stay in sync, going forward */ #define PNG_LIBPNG_VER_SHAREDLIB 16 #define PNG_LIBPNG_VER_SONUM PNG_LIBPNG_VER_SHAREDLIB /* [Deprecated] */ #define PNG_LIBPNG_VER_DLLNUM PNG_LIBPNG_VER_SHAREDLIB /* [Deprecated] */ /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */ #define PNG_LIBPNG_VER_MAJOR 1 #define PNG_LIBPNG_VER_MINOR 6 #define PNG_LIBPNG_VER_RELEASE 58 /* This should be zero for a public release, or non-zero for a * development version . #define PNG_LIBPNG_VER_BUILD 0 /* Release Status */ #define PNG_LIBPNG_BUILD_ALPHA 1 #define PNG_LIBPNG_BUILD_BETA 2 #define PNG_LIBPNG_BUILD_RC 3 #define PNG_LIBPNG_BUILD_STABLE 4 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7 /* Release-Specific Flags */ #define PNG_LIBPNG_BUILD_PATCH 8 /* Can be OR'ed with #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE/* Careful here. At one time, Guy wanted to use 082, but that * would be octal . We must not include leading zeros . * Versions 0 . 7 through 1 . 0 . 0 were in the range 0 to 100 here * ( only version 1 . 0 . 0 was mis - numbered 100 instead of 10000 ) . * From version 1 . 0 . 1 it is : * XXYYZZ , where XX = major , YY = minor , ZZ = release #define PNG_LIBPNG_VER 10658 /* 1.6.58 */ /* Library configuration: these options cannot be changed after * the library has been built . #ifndef PNGLCONF_H/* If pnglibconf.h is missing, you can * copy scripts / pnglibconf . h . prebuilt to pnglibconf . h # include "pnglibconf.h" #endif #define PNG_APNG_SUPPORTED#define PNG_READ_APNG_SUPPORTED#define PNG_WRITE_APNG_SUPPORTED#ifndef PNG_VERSION_INFO_ONLY/* Machine specific configuration. */ # include "pngconf.h" #endif /* * Added at libpng - 1 . 2 . 8 * * Ref MSDN : Private as priority over Special * VS_FF_PRIVATEBUILD File * was not * built using standard release * procedures . If this value is given , the StringFileInfo block must * contain a PrivateBuild string . * * VS_FF_SPECIALBUILD File * was * built by the original company using * standard release procedures but is a variation of the standard * file of the same version number . If this value is given , the * StringFileInfo block must contain a SpecialBuild string . #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */ # define PNG_LIBPNG_BUILD_TYPE \#else # ifdef PNG_LIBPNG_SPECIALBUILD# define PNG_LIBPNG_BUILD_TYPE \# else # define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)# endif#endif #ifndef PNG_VERSION_INFO_ONLY/* Inhibit C++ name-mangling for libpng functions but not for system calls. */ #ifdef __cplusplusextern "C" {#endif /* __cplusplus */ /* Version information for C files, stored in png.c. This had better match * the version above . #define png_libpng_ver png_get_header_ver(NULL)/* This file is arranged in several sections: * * 1 . [ omitted ] * 2 . Any configuration options that can be specified by for the application * code when it is built . ( Build time configuration is in pnglibconf . h ) * 3 . Type definitions ( base types are defined in pngconf . h ) , structure * definitions . * 4 . Exported library functions . * 5 . Simplified API . * 6 . Implementation options . * * The library source code has additional files ( principally pngpriv . h ) that * allow configuration of the library . /* Section 1: [omitted] */ /* Section 2: run time configuration * See pnglibconf . h for build time configuration * * Run time configuration allows the application to choose between * implementations of certain arithmetic APIs . The default is set * at build time and recorded in pnglibconf . h , but it is safe to * override these ( and only these ) settings . Note that this won ' t * change what the library does , only application code , and the * settings can ( and probably should ) be made on a per - file basis * by setting the # defines before including png . h * * Use macros to read integers from PNG data or use the exported * functions ? * PNG_USE_READ_MACROS : use the macros ( see below ) Note that * the macros evaluate their argument multiple times . * PNG_NO_USE_READ_MACROS : call the relevant library function . * * Use the alternative algorithm for compositing alpha samples that * does not use division ? * PNG_READ_COMPOSITE_NODIV_SUPPORTED : use the ' no division ' * algorithm . * PNG_NO_READ_COMPOSITE_NODIV : use the ' division ' algorithm . * * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is * false ? * PNG_ALLOW_BENIGN_ERRORS : map calls to the benign error * APIs to png_warning . * Otherwise the calls are mapped to png_error . /* Section 3: type definitions, including structures and compile time * constants . * See pngconf . h for base types that vary by machine / system #ifdef PNG_APNG_SUPPORTED/* dispose_op flags from inside fcTL */ #define PNG_DISPOSE_OP_NONE 0 x00#define PNG_DISPOSE_OP_BACKGROUND 0 x01#define PNG_DISPOSE_OP_PREVIOUS 0 x02/* blend_op flags from inside fcTL */ #define PNG_BLEND_OP_SOURCE 0 x00#define PNG_BLEND_OP_OVER 0 x01#endif /* APNG */ /* This triggers a compiler error in png.c, if png.c and png.h * do not agree upon the version number . typedef char *png_libpng_version_1_6_58;/* Basic control structions. Read libpng-manual.txt or libpng.3 for more info. * * png_struct is the cache of information used while reading or writing a single * PNG file . One of these is always required , although the simplified API * ( below ) hides the creation and destruction of it . typedef struct png_struct_def png_struct;typedef const png_struct * png_const_structp;typedef png_struct * png_structp;typedef png_struct * * png_structpp;/* png_info contains information read from or to be written to a PNG file. One * or more of these must exist while reading or creating a PNG file . The * information is not used by libpng during read but is used to control what * gets written when a PNG file is created . " png_get_ " function calls read * information during read and " png_set_ " functions calls write information * when creating a PNG . * been moved into a separate header file that is not accessible to * applications . Read libpng - manual . txt or libpng . 3 for more info . typedef struct png_info_def png_info;typedef png_info * png_infop;typedef const png_info * png_const_infop;typedef png_info * * png_infopp;/* Types with names ending 'p' are pointer types. The corresponding types with * names ending ' rp ' are identical pointer types except that the pointer is * marked ' restrict ' , which means that it is the only pointer to the object * passed to the function . Applications should not use the ' restrict ' types ; * it is always valid to pass ' p ' to a pointer with a function argument of the * corresponding ' rp ' type . Different compilers have different rules with * regard to type matching in the presence of ' restrict ' . For backward * compatibility libpng callbacks never have ' restrict ' in their parameters and , * consequentially , writing portable application code is extremely difficult if * an attempt is made to use ' restrict ' . typedef png_struct * PNG_RESTRICT png_structrp;typedef const png_struct * PNG_RESTRICT png_const_structrp;typedef png_info * PNG_RESTRICT png_inforp;typedef const png_info * PNG_RESTRICT png_const_inforp;/* Three color definitions. The order of the red, green, and blue, (and the * exact size ) is not important , although the size of the fields need to * be png_byte or png_uint_16 ( as defined below ) . typedef struct png_color_structtypedef png_color * png_colorp;typedef const png_color * png_const_colorp;typedef png_color * * png_colorpp;typedef struct png_color_16_struct/* used for palette files */ /* for use in red green blue files */ /* for use in grayscale files */ typedef png_color_16 * png_color_16p;typedef const png_color_16 * png_const_color_16p;typedef png_color_16 * * png_color_16pp;typedef struct png_color_8_struct/* for use in red green blue files */ /* for use in grayscale files */ /* for alpha channel files */ typedef png_color_8 * png_color_8p;typedef const png_color_8 * png_const_color_8p;typedef png_color_8 * * png_color_8pp;/* * The following two structures are used for the in - core representation * of sPLT chunks . typedef struct png_sPLT_entry_structtypedef png_sPLT_entry * png_sPLT_entryp;typedef const png_sPLT_entry * png_const_sPLT_entryp;typedef png_sPLT_entry * * png_sPLT_entrypp;/* When the depth of the sPLT palette is 8 bits, the color and alpha samples * occupy the LSB of their respective members , and the MSB of each member * is zero - filled . The frequency member always occupies the full 16 bits . typedef struct png_sPLT_struct/* palette name */ /* depth of palette samples */ /* palette entries */ /* number of palette entries */ typedef png_sPLT_t * png_sPLT_tp;typedef const png_sPLT_t * png_const_sPLT_tp;typedef png_sPLT_t * * png_sPLT_tpp;#ifdef PNG_TEXT_SUPPORTED/* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file, * and whether that contents is compressed or not . The " key " field * points to a regular zero - terminated C string . The " text " fields can be a * regular C string , an empty string , or a NULL pointer . * However , the structure returned by png_get_text ( ) will always contain * the " text " field as a regular zero - terminated C string ( possibly * empty ) , never a NULL pointer , so it can be safely used in printf ( ) and * other string - handling functions . Note that the " itxt_length " , " lang " , and * " lang_key " members of the structure only exist when the library is built * with iTXt chunk support . Prior to libpng - 1 . 4 . 0 the library was built by * default without iTXt support . Also note that when iTXt * is * supported , * the " lang " and " lang_key " fields contain NULL pointers when the * " compression " field contains * PNG_TEXT_COMPRESSION_NONE or * PNG_TEXT_COMPRESSION_zTXt . Note that the " compression value " is not the * same as what appears in the PNG tEXt / zTXt / iTXt chunk ' s " compression flag " * which is always 0 or 1 , or its " compression method " which is always 0 . typedef struct png_text_structint compression; /* compression value: - 1 : tEXt , none 0 : zTXt , deflate 1 : iTXt , none /* keyword, 1-79 character description of "text" */ /* comment, may be an empty string (ie "") /* length of the text string */ /* length of the itxt string */ /* language code, 0-79 characters /* keyword translated UTF-8 string, 0 or more typedef png_text * png_textp;typedef const png_text * png_const_textp;typedef png_text * * png_textpp;#endif /* Supported compression types for text in PNG files (tEXt, and zTXt). #define PNG_TEXT_COMPRESSION_NONE_WR -3 #define PNG_TEXT_COMPRESSION_zTXt_WR -2 #define PNG_TEXT_COMPRESSION_NONE -1 #define PNG_TEXT_COMPRESSION_zTXt 0 #define PNG_ITXT_COMPRESSION_NONE 1 #define PNG_ITXT_COMPRESSION_zTXt 2 #define PNG_TEXT_COMPRESSION_LAST 3 /* Not a valid value */ /* png_time is a way to hold the time in an machine independent way. * Two conversions are provided , both from time_t and struct tm . There * is no portable way to convert to either of these structures , as far * as I know . If you know of a portable way , send it to me . As a side * note - PNG has always been Year 2000 compliant ! typedef struct png_time_struct/* full year, as in, 1995 */ /* month of year, 1 - 12 */ /* day of month, 1 - 31 */ /* hour of day, 0 - 23 */ /* minute of hour, 0 - 59 */ /* second of minute, 0 - 60 (for leap seconds) */ typedef png_time * png_timep;typedef const png_time * png_const_timep;typedef png_time * * png_timepp;#if defined (PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\defined (PNG_USER_CHUNKS_SUPPORTED)/* png_unknown_chunk is a structure to hold queued chunks for which there is * no specific support . The idea is that we can use this to queue * up private chunks for output even though the library doesn ' t actually * know about their semantics . * * The data in the structure is set by libpng on read and used on write . typedef struct png_unknown_chunk_t5 ]; /* Textual chunk name with '\0' terminator */ /* Data, should not be modified on read! */ /* On write 'location' must be set using the flag values listed below. * Notice that on read it is set by libpng however the values stored have * more bits set than are listed below . Always treat the value as a * bitmask . On write set only one bit - setting multiple bits may cause the * chunk to be written in multiple places . /* mode of operation at read time */ typedef png_unknown_chunk * png_unknown_chunkp;typedef const png_unknown_chunk * png_const_unknown_chunkp;typedef png_unknown_chunk * * png_unknown_chunkpp;#endif /* Flag values for the unknown chunk location byte. */ #define PNG_HAVE_IHDR 0 x01#define PNG_HAVE_PLTE 0 x02#define PNG_AFTER_IDAT 0 x08/* Maximum positive integer used in PNG is (2^31)-1 */ #define PNG_UINT_31_MAX ((png_uint_32)0 x7fffffffL)#define PNG_UINT_32_MAX ((png_uint_32)(-1 ))#define PNG_SIZE_MAX ((size_t)(-1 ))/* These are constants for fixed point values encoded in the * PNG specification manner ( x100000 ) #define PNG_FP_1 100000 #define PNG_FP_HALF 50000 #define PNG_FP_MAX ((png_fixed_point)0 x7fffffffL)#define PNG_FP_MIN (-PNG_FP_MAX)/* These describe the color_type field in png_info. */ /* color type masks */ #define PNG_COLOR_MASK_PALETTE 1 #define PNG_COLOR_MASK_COLOR 2 #define PNG_COLOR_MASK_ALPHA 4 /* color types. Note that not all combinations are legal */ #define PNG_COLOR_TYPE_GRAY 0 #define PNG_COLOR_TYPE_PALETTE (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)#define PNG_COLOR_TYPE_RGB (PNG_COLOR_MASK_COLOR)#define PNG_COLOR_TYPE_RGB_ALPHA (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)/* aliases */ #define PNG_COLOR_TYPE_RGBA PNG_COLOR_TYPE_RGB_ALPHA#define PNG_COLOR_TYPE_GA PNG_COLOR_TYPE_GRAY_ALPHA/* This is for compression type. PNG 1.0-1.2 only define the single type. */ #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */ #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE/* This is for filter type. PNG 1.0-1.2 only define the single type. */ #define PNG_FILTER_TYPE_BASE 0 /* Single row per-byte filtering */ #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */ #define PNG_FILTER_TYPE_DEFAULT PNG_FILTER_TYPE_BASE/* These are for the interlacing type. These values should NOT be changed. */ #define PNG_INTERLACE_NONE 0 /* Non-interlaced image */ #define PNG_INTERLACE_ADAM7 1 /* Adam7 interlacing */ #define PNG_INTERLACE_LAST 2 /* Not a valid value */ /* These are for the oFFs chunk. These values should NOT be changed. */ #define PNG_OFFSET_PIXEL 0 /* Offset in pixels */ #define PNG_OFFSET_MICROMETER 1 /* Offset in micrometers (1/10^6 meter) */ #define PNG_OFFSET_LAST 2 /* Not a valid value */ /* These are for the pCAL chunk. These values should NOT be changed. */ #define PNG_EQUATION_LINEAR 0 /* Linear transformation */ #define PNG_EQUATION_BASE_E 1 /* Exponential base e transform */ #define PNG_EQUATION_ARBITRARY 2 /* Arbitrary base exponential transform */ #define PNG_EQUATION_HYPERBOLIC 3 /* Hyperbolic sine transformation */ #define PNG_EQUATION_LAST 4 /* Not a valid value */ /* These are for the sCAL chunk. These values should NOT be changed. */ #define PNG_SCALE_UNKNOWN 0 /* unknown unit (image scale) */ #define PNG_SCALE_METER 1 /* meters per pixel */ #define PNG_SCALE_RADIAN 2 /* radians per pixel */ #define PNG_SCALE_LAST 3 /* Not a valid value */ /* These are for the pHYs chunk. These values should NOT be changed. */ #define PNG_RESOLUTION_UNKNOWN 0 /* pixels/unknown unit (aspect ratio) */ #define PNG_RESOLUTION_METER 1 /* pixels/meter */ #define PNG_RESOLUTION_LAST 2 /* Not a valid value */ /* These are for the sRGB chunk. These values should NOT be changed. */ #define PNG_sRGB_INTENT_PERCEPTUAL 0 #define PNG_sRGB_INTENT_RELATIVE 1 #define PNG_sRGB_INTENT_SATURATION 2 #define PNG_sRGB_INTENT_ABSOLUTE 3 #define PNG_sRGB_INTENT_LAST 4 /* Not a valid value */ /* This is for text chunks */ #define PNG_KEYWORD_MAX_LENGTH 79 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */ #define PNG_MAX_PALETTE_LENGTH 256 /* These determine if an ancillary chunk's data has been successfully read * from the PNG header , or if the application has filled in the corresponding * data in the info_struct to be written into the output file . The values * of the PNG_INFO_ < chunk > defines should NOT be changed . #define PNG_INFO_gAMA 0 x0001U#define PNG_INFO_sBIT 0 x0002U#define PNG_INFO_cHRM 0 x0004U#define PNG_INFO_PLTE 0 x0008U#define PNG_INFO_tRNS 0 x0010U#define PNG_INFO_bKGD 0 x0020U#define PNG_INFO_hIST 0 x0040U#define PNG_INFO_pHYs 0 x0080U#define PNG_INFO_oFFs 0 x0100U#define PNG_INFO_tIME 0 x0200U#define PNG_INFO_pCAL 0 x0400U#define PNG_INFO_sRGB 0 x0800U /* GR-P, 0.96a */ #define PNG_INFO_iCCP 0 x1000U /* ESR, 1.0.6 */ #define PNG_INFO_sPLT 0 x2000U /* ESR, 1.0.6 */ #define PNG_INFO_sCAL 0 x4000U /* ESR, 1.0.6 */ #define PNG_INFO_IDAT 0 x8000U /* ESR, 1.0.6 */ #define PNG_INFO_eXIf 0 x10000U /* GR-P, 1.6.31 */ #define PNG_INFO_cICP 0 x20000U /* PNGv3: 1.6.45 */ #define PNG_INFO_cLLI 0 x40000U /* PNGv3: 1.6.45 */ #define PNG_INFO_mDCV 0 x80000U /* PNGv3: 1.6.45 */ /* APNG: these chunks are stored as unknown, these flags are never set * however they are provided as a convenience for implementors of APNG and * avoids any merge conflicts . * * Private chunks : these chunk names violate the chunk name recommendations * because the chunk definitions have no signature and because the private * chunks with these names have been reserved . Private definitions should * avoid them . #define PNG_INFO_acTL 0 x100000U /* PNGv3: 1.6.45: unknown */ #define PNG_INFO_fcTL 0 x200000U /* PNGv3: 1.6.45: unknown */ #define PNG_INFO_fdAT 0 x400000U /* PNGv3: 1.6.45: unknown */ /* This is used for the transformation routines, as some of them * change these values for the row . It also should enable using * the routines for other purposes . typedef struct png_row_info_struct/* width of row */ /* number of bytes in row */ /* color type of row */ /* bit depth of row */ /* number of channels (1, 2, 3, or 4) */ /* bits per pixel (depth * channels) */ typedef png_row_info * png_row_infop;typedef png_row_info * * png_row_infopp;/* These are the function types for the I/O functions and for the functions * that allow the user to override the default I / O functions with his or her * own . The png_error_ptr type should match that of user - supplied warning * and error functions , while the png_rw_ptr type should match that of the * user read / write data functions . Note that the ' write ' function must not * modify the buffer it is passed . The ' read ' function , on the other hand , is * expected to return the read data in the buffer . typedef PNG_CALLBACK(void , *png_error_ptr,typedef PNG_CALLBACK(void , *png_rw_ptr,typedef PNG_CALLBACK(void , *png_flush_ptr,typedef PNG_CALLBACK(void , *png_read_status_ptr,int ));typedef PNG_CALLBACK(void , *png_write_status_ptr,int ));#ifdef PNG_PROGRESSIVE_READ_SUPPORTEDtypedef PNG_CALLBACK(void , *png_progressive_info_ptr,typedef PNG_CALLBACK(void , *png_progressive_end_ptr,#ifdef PNG_APNG_SUPPORTEDtypedef PNG_CALLBACK(void , *png_progressive_frame_ptr,#endif /* The following callback receives png_uint_32 row_number, int pass for the * png_bytep data of the row . When transforming an interlaced image the * row number is the row number within the sub - image of the interlace pass , so * the value will increase to the height of the sub - image ( not the full image ) * then reset to 0 for the next pass . * * Use PNG_ROW_FROM_PASS_ROW ( row , pass ) and PNG_COL_FROM_PASS_COL ( col , pass ) to * find the output pixel ( x , y ) given an interlaced sub - image pixel * ( row , col , pass ) . ( See below for these macros . ) typedef PNG_CALLBACK(void , *png_progressive_row_ptr,int ));#endif #if defined (PNG_READ_USER_TRANSFORM_SUPPORTED) || \defined (PNG_WRITE_USER_TRANSFORM_SUPPORTED)typedef PNG_CALLBACK(void , *png_user_transform_ptr,#endif #ifdef PNG_USER_CHUNKS_SUPPORTEDtypedef PNG_CALLBACK(int , *png_user_chunk_ptr,#endif #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED/* not used anywhere */ /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */ #endif #ifdef PNG_SETJMP_SUPPORTED/* This must match the function definition in <setjmp.h>, and the application * must include this before png . h to obtain the definition of jmp_buf . The * function is required to be PNG_NORETURN , but this is not checked . If the * function does return the application will crash via an abort ( ) or similar * system level call . * * If you get a warning here while building the library you may need to make * changes to ensure that pnglibconf . h records the calling convention used by * your compiler . This may be very difficult - try using a different compiler * to build the library ! void , (PNGCAPI *png_longjmp_ptr), (jmp_buf, int ), typedef );#endif /* Transform masks for the high-level interface */ #define PNG_TRANSFORM_IDENTITY 0 x0000 /* read and write */ #define PNG_TRANSFORM_STRIP_16 0 x0001 /* read only */ #define PNG_TRANSFORM_STRIP_ALPHA 0 x0002 /* read only */ #define PNG_TRANSFORM_PACKING 0 x0004 /* read and write */ #define PNG_TRANSFORM_PACKSWAP 0 x0008 /* read and write */ #define PNG_TRANSFORM_EXPAND 0 x0010 /* read only */ #define PNG_TRANSFORM_INVERT_MONO 0 x0020 /* read and write */ #define PNG_TRANSFORM_SHIFT 0 x0040 /* read and write */ #define PNG_TRANSFORM_BGR 0 x0080 /* read and write */ #define PNG_TRANSFORM_SWAP_ALPHA 0 x0100 /* read and write */ #define PNG_TRANSFORM_SWAP_ENDIAN 0 x0200 /* read and write */ #define PNG_TRANSFORM_INVERT_ALPHA 0 x0400 /* read and write */ #define PNG_TRANSFORM_STRIP_FILLER 0 x0800 /* write only */ /* Added to libpng-1.2.34 */ #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER#define PNG_TRANSFORM_STRIP_FILLER_AFTER 0 x1000 /* write only */ /* Added to libpng-1.4.0 */ #define PNG_TRANSFORM_GRAY_TO_RGB 0 x2000 /* read only */ /* Added to libpng-1.5.4 */ #define PNG_TRANSFORM_EXPAND_16 0 x4000 /* read only */ #if ~0 U > 0 xffffU /* or else this might break on a 16-bit machine */ #define PNG_TRANSFORM_SCALE_16 0 x8000 /* read only */ #endif /* Flags for MNG supported features */ #define PNG_FLAG_MNG_EMPTY_PLTE 0 x01#define PNG_FLAG_MNG_FILTER_64 0 x04#define PNG_ALL_MNG_FEATURES 0 x05/* NOTE: prior to 1.5 these functions had no 'API' style declaration, * this allowed the zlib default functions to be used on Windows * platforms . In 1 . 5 the zlib default malloc ( which just calls malloc and * ignores the first argument ) should be completely compatible with the * following . typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr,typedef PNG_CALLBACK(void , *png_free_ptr,/* Section 4: exported functions * Here are the function definitions most commonly used . This is not * the place to find out how to use libpng . See libpng - manual . txt for the * full explanation , see example . c for the summary . This just provides * a simple one line description of the use of each function . * * The PNG_EXPORT ( ) and PNG_EXPORTA ( ) macros used below are defined in * pngconf . h and in the * . dfn files in the scripts directory . * * PNG_EXPORT ( ordinal , type , name , ( args ) ) ; * * ordinal : ordinal that is used while building * * . def files . The ordinal value is only * relevant when preprocessing png . h with * the * . dfn files for building symbol table * entries , and are removed by pngconf . h . * type : return type of the function * name : function name * args : function arguments , with types * * When we wish to append attributes to a function prototype we use * the PNG_EXPORTA ( ) macro instead . * * PNG_EXPORTA ( ordinal , type , name , ( args ) , attributes ) ; * * ordinal , type , name , and args : same as in PNG_EXPORT ( ) . * attributes : function attributes /* Returns the version number of the library */ 1 , png_uint_32, png_access_version_number,void ));/* Tell lib we have already handled the first <num_bytes> magic bytes. * Handling more than 8 bytes from the beginning of the file is an error . 2 , void , png_set_sig_bytes,int num_bytes));/* Check sig[start] through sig[start + num_to_check - 1] to see if it's a * PNG file . Returns zero if the supplied bytes match the 8 - byte PNG * signature , and non - zero otherwise . Having num_to_check = = 0 or * start > 7 will always fail ( i . e . return non - zero ) . 3 , int , png_sig_cmp,/* Simple signature checking function. This is the same as calling * png_check_sig ( sig , n ) : = ( png_sig_cmp ( sig , 0 , n ) = = 0 ) . * / # define png_check_sig ( sig , n ) ( png_sig_cmp ( ( sig ) , 0 , ( n ) ) = = 0 ) / * DEPRECATED * / / * Allocate and initialize png_ptr struct for reading , and any other memory . * / PNG_EXPORTA ( 4 , png_structp , png_create_read_struct , ( png_const_charp user_png_ver , png_voidp error_ptr , png_error_ptr error_fn , png_error_ptr warn_fn ) , PNG_ALLOCATED ) ; / * Allocate and initialize png_ptr struct for writing , and any other memory * / PNG_EXPORTA ( 5 , png_structp , png_create_write_struct , ( png_const_charp user_png_ver , png_voidp error_ptr , png_error_ptr error_fn , png_error_ptr warn_fn ) , PNG_ALLOCATED ) ; PNG_EXPORT ( 6 , size_t , png_get_compression_buffer_size , ( png_const_structrp png_ptr ) ) ; PNG_EXPORT ( 7 , void , png_set_compression_buffer_size , ( png_structrp png_ptr , size_t size ) ) ; / * Moved from pngconf . h in 1 . 4 . 0 and modified to ensure setjmp / longjmp * match up . * / # ifdef PNG_SETJMP_SUPPORTED / * This function returns the jmp_buf built in to * png_ptr . It must be * supplied with an appropriate ' longjmp ' function to use on that jmp_buf * unless the default error function is overridden in which case NULL is * acceptable . The size of the jmp_buf is checked against the actual size * allocated by the library - the call will return NULL on a mismatch * indicating an ABI mismatch . * / PNG_EXPORT ( 8 , jmp_buf * , png_set_longjmp_fn , ( png_structrp png_ptr , png_longjmp_ptr longjmp_fn , size_t jmp_buf_size ) ) ; # define png_jmpbuf ( png_ptr ) \ ( * png_set_longjmp_fn ( ( png_ptr ) , longjmp , ( sizeof ( jmp_buf ) ) ) ) # else # define png_jmpbuf ( png_ptr ) \ ( LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP ) # endif / * This function should be used by libpng applications in place of * longjmp ( png_ptr - > jmpbuf , val ) . If longjmp_fn ( ) has been set , it * will use it ; otherwise it will call PNG_ABORT ( ) . This function was * added in libpng - 1 . 5 . 0 . * / PNG_EXPORTA ( 9 , void , png_longjmp , ( png_const_structrp png_ptr , int val ) , PNG_NORETURN ) ; # ifdef PNG_READ_SUPPORTED / * Reset the compression stream * / PNG_EXPORTA ( 10 , int , png_reset_zstream , ( png_structrp png_ptr ) , PNG_DEPRECATED ) ; # endif / * New functions added in libpng - 1 . 0 . 2 ( not enabled by default until 1 . 2 . 0 ) * / # ifdef PNG_USER_MEM_SUPPORTED PNG_EXPORTA ( 11 , png_structp , png_create_read_struct_2 , ( png_const_charp user_png_ver , png_voidp error_ptr , png_error_ptr error_fn , png_error_ptr warn_fn , png_voidp mem_ptr , png_malloc_ptr malloc_fn , png_free_ptr free_fn ) , PNG_ALLOCATED ) ; PNG_EXPORTA ( 12 , png_structp , png_create_write_struct_2 , ( png_const_charp user_png_ver , png_voidp error_ptr , png_error_ptr error_fn , png_error_ptr warn_fn , png_voidp mem_ptr , png_malloc_ptr malloc_fn , png_free_ptr free_fn ) , PNG_ALLOCATED ) ; # endif / * Write the PNG file signature . * / PNG_EXPORT ( 13 , void , png_write_sig , ( png_structrp png_ptr ) ) ; / * Write a PNG chunk - size , type , ( optional ) data , CRC . * / PNG_EXPORT ( 14 , void , png_write_chunk , ( png_structrp png_ptr , png_const_bytep chunk_name , png_const_bytep data , size_t length ) ) ; / * Write the start of a PNG chunk - length and chunk name . * / PNG_EXPORT ( 15 , void , png_write_chunk_start , ( png_structrp png_ptr , png_const_bytep chunk_name , png_uint_32 length ) ) ; / * Write the data of a PNG chunk started with png_write_chunk_start ( ) . * / PNG_EXPORT ( 16 , void , png_write_chunk_data , ( png_structrp png_ptr , png_const_bytep data , size_t length ) ) ; / * Finish a chunk started with png_write_chunk_start ( ) ( includes CRC ) . * / PNG_EXPORT ( 17 , void , png_write_chunk_end , ( png_structrp png_ptr ) ) ; / * Allocate and initialize the info structure * / PNG_EXPORTA ( 18 , png_infop , png_create_info_struct , ( png_const_structrp png_ptr ) , PNG_ALLOCATED ) ; / * DEPRECATED : this function allowed init structures to be created using the * default allocation method ( typically malloc ) . Use is deprecated in 1 . 6 . 0 and * the API will be removed in the future . * / PNG_EXPORTA ( 19 , void , png_info_init_3 , ( png_infopp info_ptr , size_t png_info_struct_size ) , PNG_DEPRECATED ) ; / * Writes all the PNG information before the image . * / PNG_EXPORT ( 20 , void , png_write_info_before_PLTE , ( png_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 21 , void , png_write_info , ( png_structrp png_ptr , png_const_inforp info_ptr ) ) ; # ifdef PNG_SEQUENTIAL_READ_SUPPORTED / * Read the information before the actual image data . * / PNG_EXPORT ( 22 , void , png_read_info , ( png_structrp png_ptr , png_inforp info_ptr ) ) ; # endif # ifdef PNG_TIME_RFC1123_SUPPORTED / * Convert to a US string format : there is no localization support in this * routine . The original implementation used a 29 character buffer in * png_struct , this will be removed in future versions . * / # if PNG_LIBPNG_VER < 10700 / * To do : remove this from libpng17 ( and from libpng17 / png . c and pngstruct . h ) * / PNG_EXPORTA ( 23 , png_const_charp , png_convert_to_rfc1123 , ( png_structrp png_ptr , png_const_timep ptime ) , PNG_DEPRECATED ) ; # endif PNG_EXPORT ( 241 , int , png_convert_to_rfc1123_buffer , ( char out [ 29 ] , png_const_timep ptime ) ) ; # endif # ifdef PNG_CONVERT_tIME_SUPPORTED / * Convert from a struct tm to png_time * / PNG_EXPORT ( 24 , void , png_convert_from_struct_tm , ( png_timep ptime , const struct tm * ttime ) ) ; / * Convert from time_t to png_time . Uses gmtime ( ) * / PNG_EXPORT ( 25 , void , png_convert_from_time_t , ( png_timep ptime , time_t ttime ) ) ; # endif / * CONVERT_tIME * / # ifdef PNG_READ_EXPAND_SUPPORTED / * Expand data to 24 - bit RGB , or 8 - bit grayscale , with alpha if available . * / PNG_EXPORT ( 26 , void , png_set_expand , ( png_structrp png_ptr ) ) ; PNG_EXPORT ( 27 , void , png_set_expand_gray_1_2_4_to_8 , ( png_structrp png_ptr ) ) ; PNG_EXPORT ( 28 , void , png_set_palette_to_rgb , ( png_structrp png_ptr ) ) ; PNG_EXPORT ( 29 , void , png_set_tRNS_to_alpha , ( png_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_EXPAND_16_SUPPORTED / * Expand to 16 - bit channels , forces conversion of palette to RGB and expansion * of a tRNS chunk if present . * / PNG_EXPORT ( 221 , void , png_set_expand_16 , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_BGR_SUPPORTED ) | | defined ( PNG_WRITE_BGR_SUPPORTED ) / * Use blue , green , red order for pixels . * / PNG_EXPORT ( 30 , void , png_set_bgr , ( png_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED / * Expand the grayscale to 24 - bit RGB if necessary . * / PNG_EXPORT ( 31 , void , png_set_gray_to_rgb , ( png_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED / * Reduce RGB to grayscale . * / # define PNG_ERROR_ACTION_NONE 1 # define PNG_ERROR_ACTION_WARN 2 # define PNG_ERROR_ACTION_ERROR 3 # define PNG_RGB_TO_GRAY_DEFAULT ( - 1 ) / * for red / green coefficients * / PNG_FP_EXPORT ( 32 , void , png_set_rgb_to_gray , ( png_structrp png_ptr , int error_action , double red , double green ) ) PNG_FIXED_EXPORT ( 33 , void , png_set_rgb_to_gray_fixed , ( png_structrp png_ptr , int error_action , png_fixed_point red , png_fixed_point green ) ) PNG_EXPORT ( 34 , png_byte , png_get_rgb_to_gray_status , ( png_const_structrp png_ptr ) ) ; # endif # ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED PNG_EXPORT ( 35 , void , png_build_grayscale_palette , ( int bit_depth , png_colorp palette ) ) ; # endif # ifdef PNG_READ_ALPHA_MODE_SUPPORTED / * How the alpha channel is interpreted - this affects how the color channels * of a PNG file are returned to the calling application when an alpha channel , * or a tRNS chunk in a palette file , is present . * * This has no effect on the way pixels are written into a PNG output * datastream . The color samples in a PNG datastream are never premultiplied * with the alpha samples . * * The default is to return data according to the PNG specification : the alpha * channel is a linear measure of the contribution of the pixel to the * corresponding composited pixel , and the color channels are unassociated * ( not premultiplied ) . The gamma encoded color channels must be scaled * according to the contribution and to do this it is necessary to undo * the encoding , scale the color values , perform the composition and re - encode * the values . This is the ' PNG ' mode . * * The alternative is to ' associate ' the alpha with the color information by * storing color channel values that have been scaled by the alpha . * image . These are the ' STANDARD ' , ' ASSOCIATED ' or ' PREMULTIPLIED ' modes * ( the latter being the two common names for associated alpha color channels ) . * * For the ' OPTIMIZED ' mode , a pixel is treated as opaque only if the alpha * value is equal to the maximum value . * * The final choice is to gamma encode the alpha channel as well . This is * broken because , in practice , no implementation that uses this choice * correctly undoes the encoding before handling alpha composition . Use this * choice only if other serious errors in the software or hardware you use * mandate it ; the typical serious error is for dark halos to appear around * opaque areas of the composited PNG image because of arithmetic overflow . * * The API function png_set_alpha_mode specifies which of these choices to use * with an enumerated ' mode ' value and the gamma of the required output : * / # define PNG_ALPHA_PNG 0 / * according to the PNG standard * / # define PNG_ALPHA_STANDARD 1 / * according to Porter / Duff * / # define PNG_ALPHA_ASSOCIATED 1 / * as above ; this is the normal practice * / # define PNG_ALPHA_PREMULTIPLIED 1 / * as above * / # define PNG_ALPHA_OPTIMIZED 2 / * ' PNG ' for opaque pixels , else ' STANDARD ' * / # define PNG_ALPHA_BROKEN 3 / * the alpha channel is gamma encoded * / PNG_FP_EXPORT ( 227 , void , png_set_alpha_mode , ( png_structrp png_ptr , int mode , double output_gamma ) ) PNG_FIXED_EXPORT ( 228 , void , png_set_alpha_mode_fixed , ( png_structrp png_ptr , int mode , png_fixed_point output_gamma ) ) # endif # if defined ( PNG_GAMMA_SUPPORTED ) | | defined ( PNG_READ_ALPHA_MODE_SUPPORTED ) / * The output_gamma value is a screen gamma in libpng terminology : it expresses * how to decode the output values , not how they are encoded . * / # define PNG_DEFAULT_sRGB - 1 / * sRGB gamma and color space * / # define PNG_GAMMA_MAC_18 - 2 / * Old Mac ' 1 . 8 ' gamma and color space * / # define PNG_GAMMA_sRGB 220000 / * Television standards - - matches sRGB gamma * / # define PNG_GAMMA_LINEAR PNG_FP_1 / * Linear * / # endif / * The following are examples of calls to png_set_alpha_mode to achieve the * required overall gamma correction and , where necessary , alpha * premultiplication . * * png_set_alpha_mode ( pp , PNG_ALPHA_PNG , PNG_DEFAULT_sRGB ) ; * This is the default libpng handling of the alpha channel - it is not * pre - multiplied into the color components . In addition the call states * that the output is for a sRGB system and causes all PNG files without gAMA * chunks to be assumed to be encoded using sRGB . * * png_set_alpha_mode ( pp , PNG_ALPHA_PNG , PNG_GAMMA_MAC ) ; * In this case the output is assumed to be something like an sRGB conformant * display preceded by a power - law lookup table of power 1 . 45 . This is how * early Mac systems behaved . * * png_set_alpha_mode ( pp , PNG_ALPHA_STANDARD , PNG_GAMMA_LINEAR ) ; * This is the classic Jim Blinn approach and will work in academic * environments where everything is done by the book . It has the shortcoming * of assuming that input PNG data with no gamma information is linear - this * is unlikely to be correct unless the PNG files where generated locally . * Most of the time the output precision will be so low as to show * significant banding in dark areas of the image . * * png_set_expand_16 ( pp ) ; * png_set_alpha_mode ( pp , PNG_ALPHA_STANDARD , PNG_DEFAULT_sRGB ) ; * This is a somewhat more realistic Jim Blinn inspired approach . PNG files * are assumed to have the sRGB encoding if not marked with a gamma value and * the output is always 16 bits per component . This permits accurate scaling * and processing of the data . If you know that your input PNG files were * generated locally you might need to replace PNG_DEFAULT_sRGB with the * correct value for your system . * * png_set_alpha_mode ( pp , PNG_ALPHA_OPTIMIZED , PNG_DEFAULT_sRGB ) ; * If you just need to composite the PNG image onto an existing background * and if you control the code that does this you can use the optimization * setting . In this case you just copy completely opaque pixels to the * output . For pixels that are not completely transparent ( you just skip * those ) you do the composition math using png_composite or png_composite_16 * below then encode the resultant 8 - bit or 16 - bit values to match the output * encoding . * * Other cases * If neither the PNG nor the standard linear encoding work for you because * of the software or hardware you use then you have a big problem . The PNG * case will probably result in halos around the image . The linear encoding * will probably result in a washed out , too bright , image ( it ' s actually too * contrasty . ) Try the ALPHA_OPTIMIZED mode above - this will probably * substantially reduce the halos . Alternatively try : * * png_set_alpha_mode ( pp , PNG_ALPHA_BROKEN , PNG_DEFAULT_sRGB ) ; * This option will also reduce the halos , but there will be slight dark * halos round the opaque parts of the image where the background is light . * In the OPTIMIZED mode the halos will be light halos where the background * is dark . Take your pick - the halos are unavoidable unless you can get * your hardware / software fixed ! ( The OPTIMIZED approach is slightly * faster . ) * * When the default gamma of PNG files doesn ' t match the output gamma . * If you have PNG files with no gamma information png_set_alpha_mode allows * you to provide a default gamma , but it also sets the output gamma to the * matching value . If you know your PNG files have a gamma that doesn ' t * match the output you can take advantage of the fact that * png_set_alpha_mode always sets the output gamma but only sets the PNG * default if it is not already set : * * png_set_alpha_mode ( pp , PNG_ALPHA_PNG , PNG_DEFAULT_sRGB ) ; * png_set_alpha_mode ( pp , PNG_ALPHA_PNG , PNG_GAMMA_MAC ) ; * The first call sets both the default and the output gamma values , the * second call overrides the output gamma without changing the default . This * is easier than achieving the same effect with png_set_gamma . You must use * PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will * fire if more than one call to png_set_alpha_mode and png_set_background is * made in the same read operation , however multiple calls with PNG_ALPHA_PNG * are ignored . * / # ifdef PNG_READ_STRIP_ALPHA_SUPPORTED PNG_EXPORT ( 36 , void , png_set_strip_alpha , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_SWAP_ALPHA_SUPPORTED ) | | \ defined ( PNG_WRITE_SWAP_ALPHA_SUPPORTED ) PNG_EXPORT ( 37 , void , png_set_swap_alpha , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_INVERT_ALPHA_SUPPORTED ) | | \ defined ( PNG_WRITE_INVERT_ALPHA_SUPPORTED ) PNG_EXPORT ( 38 , void , png_set_invert_alpha , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_FILLER_SUPPORTED ) | | defined ( PNG_WRITE_FILLER_SUPPORTED ) / * Add a filler byte to 8 - bit or 16 - bit Gray or 24 - bit or 48 - bit RGB images . * / PNG_EXPORT ( 39 , void , png_set_filler , ( png_structrp png_ptr , png_uint_32 filler , int flags ) ) ; / * The values of the PNG_FILLER_ defines should NOT be changed * / # define PNG_FILLER_BEFORE 0 # define PNG_FILLER_AFTER 1 / * Add an alpha byte to 8 - bit or 16 - bit Gray or 24 - bit or 48 - bit RGB images . * / PNG_EXPORT ( 40 , void , png_set_add_alpha , ( png_structrp png_ptr , png_uint_32 filler , int flags ) ) ; # endif / * READ_FILLER | | WRITE_FILLER * / # if defined ( PNG_READ_SWAP_SUPPORTED ) | | defined ( PNG_WRITE_SWAP_SUPPORTED ) / * Swap bytes in 16 - bit depth files . * / PNG_EXPORT ( 41 , void , png_set_swap , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_PACK_SUPPORTED ) | | defined ( PNG_WRITE_PACK_SUPPORTED ) / * Use 1 byte per pixel in 1 , 2 , or 4 - bit depth files . * / PNG_EXPORT ( 42 , void , png_set_packing , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_PACKSWAP_SUPPORTED ) | | \ defined ( PNG_WRITE_PACKSWAP_SUPPORTED ) / * Swap packing order of pixels in bytes . * / PNG_EXPORT ( 43 , void , png_set_packswap , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_SHIFT_SUPPORTED ) | | defined ( PNG_WRITE_SHIFT_SUPPORTED ) / * Converts files to legal bit depths . * / PNG_EXPORT ( 44 , void , png_set_shift , ( png_structrp png_ptr , png_const_color_8p true_bits ) ) ; # endif # if defined ( PNG_READ_INTERLACING_SUPPORTED ) | | \ defined ( PNG_WRITE_INTERLACING_SUPPORTED ) / * Have the code handle the interlacing . Returns the number of passes . * MUST be called before png_read_update_info or png_start_read_image , * otherwise it will not have the desired effect . Note that it is still * necessary to call png_read_row or png_read_rows png_get_image_height * times for each pass . * / PNG_EXPORT ( 45 , int , png_set_interlace_handling , ( png_structrp png_ptr ) ) ; # endif # if defined ( PNG_READ_INVERT_SUPPORTED ) | | defined ( PNG_WRITE_INVERT_SUPPORTED ) / * Invert monochrome files * / PNG_EXPORT ( 46 , void , png_set_invert_mono , ( png_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_BACKGROUND_SUPPORTED / * Handle alpha and tRNS by replacing with a background color . Prior to * libpng - 1 . 5 . 4 this API must not be called before the PNG file header has been * read . Doing so will result in unexpected behavior and possible warnings or * errors if the PNG file contains a bKGD chunk . * / PNG_FP_EXPORT ( 47 , void , png_set_background , ( png_structrp png_ptr , png_const_color_16p background_color , int background_gamma_code , int need_expand , double background_gamma ) ) PNG_FIXED_EXPORT ( 215 , void , png_set_background_fixed , ( png_structrp png_ptr , png_const_color_16p background_color , int background_gamma_code , int need_expand , png_fixed_point background_gamma ) ) # endif # ifdef PNG_READ_BACKGROUND_SUPPORTED # define PNG_BACKGROUND_GAMMA_UNKNOWN 0 # define PNG_BACKGROUND_GAMMA_SCREEN 1 # define PNG_BACKGROUND_GAMMA_FILE 2 # define PNG_BACKGROUND_GAMMA_UNIQUE 3 # endif # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED / * Scale a 16 - bit depth file down to 8 - bit , accurately . * / PNG_EXPORT ( 229 , void , png_set_scale_16 , ( png_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED # define PNG_READ_16_TO_8_SUPPORTED / * Name prior to 1 . 5 . 4 * / / * Strip the second byte of information from a 16 - bit depth file . * / PNG_EXPORT ( 48 , void , png_set_strip_16 , ( png_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_QUANTIZE_SUPPORTED / * Turn on quantizing , and reduce the palette to the number of colors * available . * / PNG_EXPORT ( 49 , void , png_set_quantize , ( png_structrp png_ptr , png_colorp palette , int num_palette , int maximum_colors , png_const_uint_16p histogram , int full_quantize ) ) ; # endif # ifdef PNG_READ_GAMMA_SUPPORTED / * The threshold on gamma processing is configurable but hard - wired into the * library . The following is the floating point variant . * / # define PNG_GAMMA_THRESHOLD ( PNG_GAMMA_THRESHOLD_FIXED * . 00001 ) / * Handle gamma correction . Screen_gamma = ( display_exponent ) . * NOTE : this API simply sets the screen and file gamma values . It will * therefore override the value for gamma in a PNG file if it is called after * the file header has been read - use with care - call before reading the PNG * file for best results ! * * These routines accept the same gamma values as png_set_alpha_mode ( described * above ) . The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either * API ( floating point or fixed . ) Notice , however , that the ' file_gamma ' value * is the inverse of a ' screen gamma ' value . * / PNG_FP_EXPORT ( 50 , void , png_set_gamma , ( png_structrp png_ptr , double screen_gamma , double override_file_gamma ) ) PNG_FIXED_EXPORT ( 208 , void , png_set_gamma_fixed , ( png_structrp png_ptr , png_fixed_point screen_gamma , png_fixed_point override_file_gamma ) ) # endif # ifdef PNG_WRITE_FLUSH_SUPPORTED / * Set how many lines between output flushes - 0 for no flushing * / PNG_EXPORT ( 51 , void , png_set_flush , ( png_structrp png_ptr , int nrows ) ) ; / * Flush the current PNG output buffer * / PNG_EXPORT ( 52 , void , png_write_flush , ( png_structrp png_ptr ) ) ; # endif / * Optional update palette with requested transformations * / PNG_EXPORT ( 53 , void , png_start_read_image , ( png_structrp png_ptr ) ) ; / * Optional call to update the users info structure * / PNG_EXPORT ( 54 , void , png_read_update_info , ( png_structrp png_ptr , png_inforp info_ptr ) ) ; # ifdef PNG_SEQUENTIAL_READ_SUPPORTED / * Read one or more rows of image data . * / PNG_EXPORT ( 55 , void , png_read_rows , ( png_structrp png_ptr , png_bytepp row , png_bytepp display_row , png_uint_32 num_rows ) ) ; # endif # ifdef PNG_SEQUENTIAL_READ_SUPPORTED / * Read a row of data . * / PNG_EXPORT ( 56 , void , png_read_row , ( png_structrp png_ptr , png_bytep row , png_bytep display_row ) ) ; # endif # ifdef PNG_SEQUENTIAL_READ_SUPPORTED / * Read the whole image into memory at once . * / PNG_EXPORT ( 57 , void , png_read_image , ( png_structrp png_ptr , png_bytepp image ) ) ; # endif / * Write a row of image data * / PNG_EXPORT ( 58 , void , png_write_row , ( png_structrp png_ptr , png_const_bytep row ) ) ; / * Write a few rows of image data : ( * row ) is not written ; however , the type * is declared as writeable to maintain compatibility with previous versions * of libpng and to allow the ' display_row ' array from read_rows to be passed * unchanged to write_rows . * / PNG_EXPORT ( 59 , void , png_write_rows , ( png_structrp png_ptr , png_bytepp row , png_uint_32 num_rows ) ) ; / * Write the image data * / PNG_EXPORT ( 60 , void , png_write_image , ( png_structrp png_ptr , png_bytepp image ) ) ; / * Write the end of the PNG file . * / PNG_EXPORT ( 61 , void , png_write_end , ( png_structrp png_ptr , png_inforp info_ptr ) ) ; # ifdef PNG_SEQUENTIAL_READ_SUPPORTED / * Read the end of the PNG file . * / PNG_EXPORT ( 62 , void , png_read_end , ( png_structrp png_ptr , png_inforp info_ptr ) ) ; # endif / * Free any memory associated with the png_info_struct * / PNG_EXPORT ( 63 , void , png_destroy_info_struct , ( png_const_structrp png_ptr , png_infopp info_ptr_ptr ) ) ; / * Free any memory associated with the png_struct and the png_info_structs * / PNG_EXPORT ( 64 , void , png_destroy_read_struct , ( png_structpp png_ptr_ptr , png_infopp info_ptr_ptr , png_infopp end_info_ptr_ptr ) ) ; / * Free any memory associated with the png_struct and the png_info_structs * / PNG_EXPORT ( 65 , void , png_destroy_write_struct , ( png_structpp png_ptr_ptr , png_infopp info_ptr_ptr ) ) ; / * Set the libpng method of handling chunk CRC errors * / PNG_EXPORT ( 66 , void , png_set_crc_action , ( png_structrp png_ptr , int crit_action , int ancil_action ) ) ; / * Values for png_set_crc_action ( ) say how to handle CRC errors in * ancillary and critical chunks , and whether to use the data contained * therein . Note that it is impossible to " discard " data in a critical * chunk . For versions prior to 0 . 90 , the action was always error / quit , * whereas in version 0 . 90 and later , the action for CRC errors in ancillary * chunks is warn / discard . These values should NOT be changed . * * value action : critical action : ancillary * / # define PNG_CRC_DEFAULT 0 / * error / quit warn / discard data * / # define PNG_CRC_ERROR_QUIT 1 / * error / quit error / quit * / # define PNG_CRC_WARN_DISCARD 2 / * ( INVALID ) warn / discard data * / # define PNG_CRC_WARN_USE 3 / * warn / use data warn / use data * / # define PNG_CRC_QUIET_USE 4 / * quiet / use data quiet / use data * / # define PNG_CRC_NO_CHANGE 5 / * use current value use current value * / # ifdef PNG_WRITE_SUPPORTED / * These functions give the user control over the scan - line filtering in * libpng and the compression methods used by zlib . These functions are * mainly useful for testing , as the defaults should work with most users . * Those users who are tight on memory or want faster performance at the * expense of compression can modify them . See the compression library * header file ( zlib . h ) for an explanation of the compression functions . * / / * Set the filtering method ( s ) used by libpng . Currently , the only valid * value for " method " is 0 . * / PNG_EXPORT ( 67 , void , png_set_filter , ( png_structrp png_ptr , int method , int filters ) ) ; # endif / * WRITE * / / * Flags for png_set_filter ( ) to say which filters to use . The flags * are chosen so that they don ' t conflict with real filter types * below , in case they are supplied instead of the # defined constants . * These values should NOT be changed . * / # define PNG_NO_FILTERS 0 x00 # define PNG_FILTER_NONE 0 x08 # define PNG_FILTER_SUB 0 x10 # define PNG_FILTER_UP 0 x20 # define PNG_FILTER_AVG 0 x40 # define PNG_FILTER_PAETH 0 x80 # define PNG_FAST_FILTERS ( PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP ) # define PNG_ALL_FILTERS ( PNG_FAST_FILTERS | PNG_FILTER_AVG | PNG_FILTER_PAETH ) / * Filter values ( not flags ) - used in pngwrite . c , pngwutil . c for now . * These defines should NOT be changed . * / # define PNG_FILTER_VALUE_NONE 0 # define PNG_FILTER_VALUE_SUB 1 # define PNG_FILTER_VALUE_UP 2 # define PNG_FILTER_VALUE_AVG 3 # define PNG_FILTER_VALUE_PAETH 4 # define PNG_FILTER_VALUE_LAST 5 # ifdef PNG_WRITE_SUPPORTED # ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED / * DEPRECATED * / PNG_FP_EXPORT ( 68 , void , png_set_filter_heuristics , ( png_structrp png_ptr , int heuristic_method , int num_weights , png_const_doublep filter_weights , png_const_doublep filter_costs ) ) PNG_FIXED_EXPORT ( 209 , void , png_set_filter_heuristics_fixed , ( png_structrp png_ptr , int heuristic_method , int num_weights , png_const_fixed_point_p filter_weights , png_const_fixed_point_p filter_costs ) ) # endif / * WRITE_WEIGHTED_FILTER * / / * The following are no longer used and will be removed from libpng - 1 . 7 : * / # define PNG_FILTER_HEURISTIC_DEFAULT 0 / * Currently " UNWEIGHTED " * / # define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 / * Used by libpng < 0 . 95 * / # define PNG_FILTER_HEURISTIC_WEIGHTED 2 / * Experimental feature * / # define PNG_FILTER_HEURISTIC_LAST 3 / * Not a valid value * / / * Set the library compression level . Currently , valid values range from * 0 - 9 , corresponding directly to the zlib compression levels 0 - 9 * ( 0 - no compression , 9 - " maximal " compression ) . Note that tests have * shown that zlib compression levels 3 - 6 usually perform as well as level 9 * for PNG images , and do considerably fewer calculations . In the future , * these values may not correspond directly to the zlib compression levels . * / # ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED PNG_EXPORT ( 69 , void , png_set_compression_level , ( png_structrp png_ptr , int level ) ) ; PNG_EXPORT ( 70 , void , png_set_compression_mem_level , ( png_structrp png_ptr , int mem_level ) ) ; PNG_EXPORT ( 71 , void , png_set_compression_strategy , ( png_structrp png_ptr , int strategy ) ) ; / * If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined , libpng will use a * smaller value of window_bits if it can do so safely . * / PNG_EXPORT ( 72 , void , png_set_compression_window_bits , ( png_structrp png_ptr , int window_bits ) ) ; PNG_EXPORT ( 73 , void , png_set_compression_method , ( png_structrp png_ptr , int method ) ) ; # endif / * WRITE_CUSTOMIZE_COMPRESSION * / # ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED / * Also set zlib parameters for compressing non - IDAT chunks * / PNG_EXPORT ( 222 , void , png_set_text_compression_level , ( png_structrp png_ptr , int level ) ) ; PNG_EXPORT ( 223 , void , png_set_text_compression_mem_level , ( png_structrp png_ptr , int mem_level ) ) ; PNG_EXPORT ( 224 , void , png_set_text_compression_strategy , ( png_structrp png_ptr , int strategy ) ) ; / * If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined , libpng will use a * smaller value of window_bits if it can do so safely . * / PNG_EXPORT ( 225 , void , png_set_text_compression_window_bits , ( png_structrp png_ptr , int window_bits ) ) ; PNG_EXPORT ( 226 , void , png_set_text_compression_method , ( png_structrp png_ptr , int method ) ) ; # endif / * WRITE_CUSTOMIZE_ZTXT_COMPRESSION * / # endif / * WRITE * / / * These next functions are called for input / output , memory , and error * handling . They are in the file pngrio . c , pngwio . c , and pngerror . c , * and call standard C I / O routines such as fread ( ) , fwrite ( ) , and * fprintf ( ) . These functions can be made to use other I / O routines * at run time for those applications that need to handle I / O in a * different manner by calling png_set_ ? ? ? _ fn ( ) . See libpng - manual . txt for * more information . * / # ifdef PNG_STDIO_SUPPORTED / * Initialize the input / output for the PNG file to the default functions . * / PNG_EXPORT ( 74 , void , png_init_io , ( png_structrp png_ptr , FILE * fp ) ) ; # endif / * Replace the ( error and abort ) , and warning functions with user * supplied functions . If no messages are to be printed you must still * write and use replacement functions . The replacement error_fn should * still do a longjmp to the last setjmp location if you are using this * method of error handling . If error_fn or warning_fn is NULL , the * default function will be used . * / PNG_EXPORT ( 75 , void , png_set_error_fn , ( png_structrp png_ptr , png_voidp error_ptr , png_error_ptr error_fn , png_error_ptr warning_fn ) ) ; / * Return the user pointer associated with the error functions * / PNG_EXPORT ( 76 , png_voidp , png_get_error_ptr , ( png_const_structrp png_ptr ) ) ; / * Replace the default data output functions with a user supplied one ( s ) . * If buffered output is not used , then output_flush_fn can be set to NULL . * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time * output_flush_fn will be ignored ( and thus can be NULL ) . * It is probably a mistake to use NULL for output_flush_fn if * write_data_fn is not also NULL unless you have built libpng with * PNG_WRITE_FLUSH_SUPPORTED undefined , because in this case libpng ' s * default flush function , which uses the standard * FILE structure , will * be used . * / PNG_EXPORT ( 77 , void , png_set_write_fn , ( png_structrp png_ptr , png_voidp io_ptr , png_rw_ptr write_data_fn , png_flush_ptr output_flush_fn ) ) ; / * Replace the default data input function with a user supplied one . * / PNG_EXPORT ( 78 , void , png_set_read_fn , ( png_structrp png_ptr , png_voidp io_ptr , png_rw_ptr read_data_fn ) ) ; / * Return the user pointer associated with the I / O functions * / PNG_EXPORT ( 79 , png_voidp , png_get_io_ptr , ( png_const_structrp png_ptr ) ) ; PNG_EXPORT ( 80 , void , png_set_read_status_fn , ( png_structrp png_ptr , png_read_status_ptr read_row_fn ) ) ; PNG_EXPORT ( 81 , void , png_set_write_status_fn , ( png_structrp png_ptr , png_write_status_ptr write_row_fn ) ) ; # ifdef PNG_USER_MEM_SUPPORTED / * Replace the default memory allocation functions with user supplied one ( s ) . * / PNG_EXPORT ( 82 , void , png_set_mem_fn , ( png_structrp png_ptr , png_voidp mem_ptr , png_malloc_ptr malloc_fn , png_free_ptr free_fn ) ) ; / * Return the user pointer associated with the memory functions * / PNG_EXPORT ( 83 , png_voidp , png_get_mem_ptr , ( png_const_structrp png_ptr ) ) ; # endif # ifdef PNG_READ_USER_TRANSFORM_SUPPORTED PNG_EXPORT ( 84 , void , png_set_read_user_transform_fn , ( png_structrp png_ptr , png_user_transform_ptr read_user_transform_fn ) ) ; # endif # ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED PNG_EXPORT ( 85 , void , png_set_write_user_transform_fn , ( png_structrp png_ptr , png_user_transform_ptr write_user_transform_fn ) ) ; # endif # ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED PNG_EXPORT ( 86 , void , png_set_user_transform_info , ( png_structrp png_ptr , png_voidp user_transform_ptr , int user_transform_depth , int user_transform_channels ) ) ; / * Return the user pointer associated with the user transform functions * / PNG_EXPORT ( 87 , png_voidp , png_get_user_transform_ptr , ( png_const_structrp png_ptr ) ) ; # endif # ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED / * Return information about the row currently being processed . Note that these * APIs do not fail but will return unexpected results if called outside a user * transform callback . Also note that when transforming an interlaced image the * row number is the row number within the sub - image of the interlace pass , so * the value will increase to the height of the sub - image ( not the full image ) * then reset to 0 for the next pass . * * Use PNG_ROW_FROM_PASS_ROW ( row , pass ) and PNG_COL_FROM_PASS_COL ( col , pass ) to * find the output pixel ( x , y ) given an interlaced sub - image pixel * ( row , col , pass ) . ( See below for these macros . ) * / PNG_EXPORT ( 217 , png_uint_32 , png_get_current_row_number , ( png_const_structrp ) ) ; PNG_EXPORT ( 218 , png_byte , png_get_current_pass_number , ( png_const_structrp ) ) ; # endif # ifdef PNG_READ_USER_CHUNKS_SUPPORTED / * This callback is called only for * unknown * chunks . If * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known * chunks to be treated as unknown , however in this case the callback must do * any processing required by the chunk ( e . g . by calling the appropriate * png_set_ APIs . ) * * There is no write support - on write , by default , all the chunks in the * ' unknown ' list are written in the specified position . * * The integer return from the callback function is interpreted thus : * * negative : An error occurred ; png_chunk_error will be called . * zero : The chunk was not handled , the chunk will be saved . A critical * chunk will cause an error at this point unless it is to be saved . * positive : The chunk was handled , libpng will ignore / discard it . * * See " INTERACTION WITH USER CHUNK CALLBACKS " below for important notes about * how this behavior will change in libpng 1 . 7 * / PNG_EXPORT ( 88 , void , png_set_read_user_chunk_fn , ( png_structrp png_ptr , png_voidp user_chunk_ptr , png_user_chunk_ptr read_user_chunk_fn ) ) ; # endif # ifdef PNG_USER_CHUNKS_SUPPORTED PNG_EXPORT ( 89 , png_voidp , png_get_user_chunk_ptr , ( png_const_structrp png_ptr ) ) ; # endif # ifdef PNG_PROGRESSIVE_READ_SUPPORTED / * Sets the function callbacks for the push reader , and a pointer to a * user - defined structure available to the callback functions . * / PNG_EXPORT ( 90 , void , png_set_progressive_read_fn , ( png_structrp png_ptr , png_voidp progressive_ptr , png_progressive_info_ptr info_fn , png_progressive_row_ptr row_fn , png_progressive_end_ptr end_fn ) ) ; / * Returns the user pointer associated with the push read functions * / PNG_EXPORT ( 91 , png_voidp , png_get_progressive_ptr , ( png_const_structrp png_ptr ) ) ; / * Function to be called when data becomes available * / PNG_EXPORT ( 92 , void , png_process_data , ( png_structrp png_ptr , png_inforp info_ptr , png_bytep buffer , size_t buffer_size ) ) ; / * A function which may be called * only * within png_process_data to stop the * processing of any more data . The function returns the number of bytes * remaining , excluding any that libpng has cached internally . A subsequent * call to png_process_data must supply these bytes again . If the argument * ' save ' is set to true the routine will first save all the pending data and * will always return 0 . * / PNG_EXPORT ( 219 , size_t , png_process_data_pause , ( png_structrp , int save ) ) ; / * A function which may be called * only * outside ( after ) a call to * png_process_data . It returns the number of bytes of data to skip in the * input . Normally it will return 0 , but if it returns a non - zero value the * application must skip than number of bytes of input data and pass the * following data to the next call to png_process_data . * / PNG_EXPORT ( 220 , png_uint_32 , png_process_data_skip , ( png_structrp ) ) ; / * Function that combines rows . ' new_row ' is a flag that should come from * the callback and be non - NULL if anything needs to be done ; the library * stores its own version of the new data internally and ignores the passed * in value . * / PNG_EXPORT ( 93 , void , png_progressive_combine_row , ( png_const_structrp png_ptr , png_bytep old_row , png_const_bytep new_row ) ) ; # endif / * PROGRESSIVE_READ * / PNG_EXPORTA ( 94 , png_voidp , png_malloc , ( png_const_structrp png_ptr , png_alloc_size_t size ) , PNG_ALLOCATED ) ; / * Added at libpng version 1 . 4 . 0 * / PNG_EXPORTA ( 95 , png_voidp , png_calloc , ( png_const_structrp png_ptr , png_alloc_size_t size ) , PNG_ALLOCATED ) ; / * Added at libpng version 1 . 2 . 4 * / PNG_EXPORTA ( 96 , png_voidp , png_malloc_warn , ( png_const_structrp png_ptr , png_alloc_size_t size ) , PNG_ALLOCATED ) ; / * Frees a pointer allocated by png_malloc ( ) * / PNG_EXPORT ( 97 , void , png_free , ( png_const_structrp png_ptr , png_voidp ptr ) ) ; / * Free data that was allocated internally * / PNG_EXPORT ( 98 , void , png_free_data , ( png_const_structrp png_ptr , png_inforp info_ptr , png_uint_32 free_me , int num ) ) ; / * Reassign the responsibility for freeing existing data , whether allocated * by libpng or by the application ; this works on the png_info structure passed * in , without changing the state for other png_info structures . * / PNG_EXPORT ( 99 , void , png_data_freer , ( png_const_structrp png_ptr , png_inforp info_ptr , int freer , png_uint_32 mask ) ) ; / * Assignments for png_data_freer * / # define PNG_DESTROY_WILL_FREE_DATA 1 # define PNG_SET_WILL_FREE_DATA 1 # define PNG_USER_WILL_FREE_DATA 2 / * Flags for png_ptr - > free_me and info_ptr - > free_me * / # define PNG_FREE_HIST 0 x0008U # define PNG_FREE_ICCP 0 x0010U # define PNG_FREE_SPLT 0 x0020U # define PNG_FREE_ROWS 0 x0040U # define PNG_FREE_PCAL 0 x0080U # define PNG_FREE_SCAL 0 x0100U # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED # define PNG_FREE_UNKN 0 x0200U # endif / * PNG_FREE_LIST 0 x0400U removed in 1 . 6 . 0 because it is ignored * / # define PNG_FREE_PLTE 0 x1000U # define PNG_FREE_TRNS 0 x2000U # define PNG_FREE_TEXT 0 x4000U # define PNG_FREE_EXIF 0 x8000U / * Added at libpng - 1 . 6 . 31 * / # define PNG_FREE_ALL 0 xffffU # define PNG_FREE_MUL 0 x4220U / * PNG_FREE_SPLT | PNG_FREE_TEXT | PNG_FREE_UNKN * / # ifdef PNG_USER_MEM_SUPPORTED PNG_EXPORTA ( 100 , png_voidp , png_malloc_default , ( png_const_structrp png_ptr , png_alloc_size_t size ) , PNG_ALLOCATED PNG_DEPRECATED ) ; PNG_EXPORTA ( 101 , void , png_free_default , ( png_const_structrp png_ptr , png_voidp ptr ) , PNG_DEPRECATED ) ; # endif # ifdef PNG_ERROR_TEXT_SUPPORTED / * Fatal error in PNG image of libpng - can ' t continue * / PNG_EXPORTA ( 102 , void , png_error , ( png_const_structrp png_ptr , png_const_charp error_message ) , PNG_NORETURN ) ; / * The same , but the chunk name is prepended to the error string . * / PNG_EXPORTA ( 103 , void , png_chunk_error , ( png_const_structrp png_ptr , png_const_charp error_message ) , PNG_NORETURN ) ; # else / * Fatal error in PNG image of libpng - can ' t continue * / PNG_EXPORTA ( 104 , void , png_err , ( png_const_structrp png_ptr ) , PNG_NORETURN ) ; # define png_error ( s1 , s2 ) png_err ( s1 ) # define png_chunk_error ( s1 , s2 ) png_err ( s1 ) # endif # ifdef PNG_WARNINGS_SUPPORTED / * Non - fatal error in libpng . Can continue , but may have a problem . * / PNG_EXPORT ( 105 , void , png_warning , ( png_const_structrp png_ptr , png_const_charp warning_message ) ) ; / * Non - fatal error in libpng , chunk name is prepended to message . * / PNG_EXPORT ( 106 , void , png_chunk_warning , ( png_const_structrp png_ptr , png_const_charp warning_message ) ) ; # else # define png_warning ( s1 , s2 ) ( ( void ) ( s1 ) ) # define png_chunk_warning ( s1 , s2 ) ( ( void ) ( s1 ) ) # endif # ifdef PNG_BENIGN_ERRORS_SUPPORTED / * Benign error in libpng . Can continue , but may have a problem . * User can choose whether to handle as a fatal error or as a warning . * / PNG_EXPORT ( 107 , void , png_benign_error , ( png_const_structrp png_ptr , png_const_charp warning_message ) ) ; # ifdef PNG_READ_SUPPORTED / * Same , chunk name is prepended to message ( only during read ) * / PNG_EXPORT ( 108 , void , png_chunk_benign_error , ( png_const_structrp png_ptr , png_const_charp warning_message ) ) ; # endif PNG_EXPORT ( 109 , void , png_set_benign_errors , ( png_structrp png_ptr , int allowed ) ) ; # else # ifdef PNG_ALLOW_BENIGN_ERRORS # define png_benign_error png_warning # define png_chunk_benign_error png_chunk_warning # else # define png_benign_error png_error # define png_chunk_benign_error png_chunk_error # endif # endif / * The png_set_ < chunk > functions are for storing values in the png_info_struct . * Similarly , the png_get_ < chunk > calls are used to read values from the * png_info_struct , either storing the parameters in the passed variables , or * setting pointers into the png_info_struct where the data is stored . The * png_get_ < chunk > functions return a non - zero value if the data was available * in info_ptr , or return zero and do not change any of the parameters if the * data was not available . * * These functions should be used instead of directly accessing png_info * to avoid problems with future changes in the size and internal layout of * png_info_struct . * / / * Returns " flag " if chunk data is valid in info_ptr . * / PNG_EXPORT ( 110 , png_uint_32 , png_get_valid , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_uint_32 flag ) ) ; / * Returns number of bytes needed to hold a transformed row . * / PNG_EXPORT ( 111 , size_t , png_get_rowbytes , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; # ifdef PNG_INFO_IMAGE_SUPPORTED / * Returns row_pointers , which is an array of pointers to scanlines that was * returned from png_read_png ( ) . * / PNG_EXPORT ( 112 , png_bytepp , png_get_rows , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Set row_pointers , which is an array of pointers to scanlines for use * by png_write_png ( ) . * / PNG_EXPORT ( 113 , void , png_set_rows , ( png_const_structrp png_ptr , png_inforp info_ptr , png_bytepp row_pointers ) ) ; # endif / * Returns number of color channels in image . * / PNG_EXPORT ( 114 , png_byte , png_get_channels , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; # ifdef PNG_EASY_ACCESS_SUPPORTED / * Returns image width in pixels . * / PNG_EXPORT ( 115 , png_uint_32 , png_get_image_width , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image height in pixels . * / PNG_EXPORT ( 116 , png_uint_32 , png_get_image_height , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image bit_depth . * / PNG_EXPORT ( 117 , png_byte , png_get_bit_depth , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image color_type . * / PNG_EXPORT ( 118 , png_byte , png_get_color_type , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image filter_type . * / PNG_EXPORT ( 119 , png_byte , png_get_filter_type , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image interlace_type . * / PNG_EXPORT ( 120 , png_byte , png_get_interlace_type , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image compression_type . * / PNG_EXPORT ( 121 , png_byte , png_get_compression_type , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns image resolution in pixels per meter , from pHYs chunk data . * / PNG_EXPORT ( 122 , png_uint_32 , png_get_pixels_per_meter , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 123 , png_uint_32 , png_get_x_pixels_per_meter , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 124 , png_uint_32 , png_get_y_pixels_per_meter , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; / * Returns pixel aspect ratio , computed from pHYs chunk data . * / PNG_FP_EXPORT ( 125 , float , png_get_pixel_aspect_ratio , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) PNG_FIXED_EXPORT ( 210 , png_fixed_point , png_get_pixel_aspect_ratio_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) / * Returns image x , y offset in pixels or microns , from oFFs chunk data . * / PNG_EXPORT ( 126 , png_int_32 , png_get_x_offset_pixels , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 127 , png_int_32 , png_get_y_offset_pixels , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 128 , png_int_32 , png_get_x_offset_microns , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 129 , png_int_32 , png_get_y_offset_microns , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; # endif / * EASY_ACCESS * / # ifdef PNG_READ_SUPPORTED / * Returns pointer to signature string read from PNG header * / PNG_EXPORT ( 130 , png_const_bytep , png_get_signature , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; # endif # ifdef PNG_bKGD_SUPPORTED PNG_EXPORT ( 131 , png_uint_32 , png_get_bKGD , ( png_const_structrp png_ptr , png_inforp info_ptr , png_color_16p * background ) ) ; # endif # ifdef PNG_bKGD_SUPPORTED PNG_EXPORT ( 132 , void , png_set_bKGD , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_color_16p background ) ) ; # endif # ifdef PNG_cHRM_SUPPORTED PNG_FP_EXPORT ( 133 , png_uint_32 , png_get_cHRM , ( png_const_structrp png_ptr , png_const_inforp info_ptr , double * white_x , double * white_y , double * red_x , double * red_y , double * green_x , double * green_y , double * blue_x , double * blue_y ) ) PNG_FP_EXPORT ( 230 , png_uint_32 , png_get_cHRM_XYZ , ( png_const_structrp png_ptr , png_const_inforp info_ptr , double * red_X , double * red_Y , double * red_Z , double * green_X , double * green_Y , double * green_Z , double * blue_X , double * blue_Y , double * blue_Z ) ) PNG_FIXED_EXPORT ( 134 , png_uint_32 , png_get_cHRM_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_fixed_point * int_white_x , png_fixed_point * int_white_y , png_fixed_point * int_red_x , png_fixed_point * int_red_y , png_fixed_point * int_green_x , png_fixed_point * int_green_y , png_fixed_point * int_blue_x , png_fixed_point * int_blue_y ) ) PNG_FIXED_EXPORT ( 231 , png_uint_32 , png_get_cHRM_XYZ_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_fixed_point * int_red_X , png_fixed_point * int_red_Y , png_fixed_point * int_red_Z , png_fixed_point * int_green_X , png_fixed_point * int_green_Y , png_fixed_point * int_green_Z , png_fixed_point * int_blue_X , png_fixed_point * int_blue_Y , png_fixed_point * int_blue_Z ) ) # endif # ifdef PNG_cHRM_SUPPORTED PNG_FP_EXPORT ( 135 , void , png_set_cHRM , ( png_const_structrp png_ptr , png_inforp info_ptr , double white_x , double white_y , double red_x , double red_y , double green_x , double green_y , double blue_x , double blue_y ) ) PNG_FP_EXPORT ( 232 , void , png_set_cHRM_XYZ , ( png_const_structrp png_ptr , png_inforp info_ptr , double red_X , double red_Y , double red_Z , double green_X , double green_Y , double green_Z , double blue_X , double blue_Y , double blue_Z ) ) PNG_FIXED_EXPORT ( 136 , void , png_set_cHRM_fixed , ( png_const_structrp png_ptr , png_inforp info_ptr , png_fixed_point int_white_x , png_fixed_point int_white_y , png_fixed_point int_red_x , png_fixed_point int_red_y , png_fixed_point int_green_x , png_fixed_point int_green_y , png_fixed_point int_blue_x , png_fixed_point int_blue_y ) ) PNG_FIXED_EXPORT ( 233 , void , png_set_cHRM_XYZ_fixed , ( png_const_structrp png_ptr , png_inforp info_ptr , png_fixed_point int_red_X , png_fixed_point int_red_Y , png_fixed_point int_red_Z , png_fixed_point int_green_X , png_fixed_point int_green_Y , png_fixed_point int_green_Z , png_fixed_point int_blue_X , png_fixed_point int_blue_Y , png_fixed_point int_blue_Z ) ) # endif # ifdef PNG_cICP_SUPPORTED PNG_EXPORT ( 250 , png_uint_32 , png_get_cICP , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_bytep colour_primaries , png_bytep transfer_function , png_bytep matrix_coefficients , png_bytep video_full_range_flag ) ) ; # endif # ifdef PNG_cICP_SUPPORTED PNG_EXPORT ( 251 , void , png_set_cICP , ( png_const_structrp png_ptr , png_inforp info_ptr , png_byte colour_primaries , png_byte transfer_function , png_byte matrix_coefficients , png_byte video_full_range_flag ) ) ; # endif # ifdef PNG_cLLI_SUPPORTED PNG_FP_EXPORT ( 252 , png_uint_32 , png_get_cLLI , ( png_const_structrp png_ptr , png_const_inforp info_ptr , double * maximum_content_light_level , double * maximum_frame_average_light_level ) ) PNG_FIXED_EXPORT ( 253 , png_uint_32 , png_get_cLLI_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr , / * The values below are in cd / m2 ( nits ) and are scaled by 10 , 000 ; not * 100 , 000 as in the case of png_fixed_point . * / png_uint_32p maximum_content_light_level_scaled_by_10000 , png_uint_32p maximum_frame_average_light_level_scaled_by_10000 ) ) # endif # ifdef PNG_cLLI_SUPPORTED PNG_FP_EXPORT ( 254 , void , png_set_cLLI , ( png_const_structrp png_ptr , png_inforp info_ptr , double maximum_content_light_level , double maximum_frame_average_light_level ) ) PNG_FIXED_EXPORT ( 255 , void , png_set_cLLI_fixed , ( png_const_structrp png_ptr , png_inforp info_ptr , / * The values below are in cd / m2 ( nits ) and are scaled by 10 , 000 ; not * 100 , 000 as in the case of png_fixed_point . * / png_uint_32 maximum_content_light_level_scaled_by_10000 , png_uint_32 maximum_frame_average_light_level_scaled_by_10000 ) ) # endif # ifdef PNG_eXIf_SUPPORTED PNG_EXPORT ( 246 , png_uint_32 , png_get_eXIf , ( png_const_structrp png_ptr , png_inforp info_ptr , png_bytep * exif ) ) ; PNG_EXPORT ( 247 , void , png_set_eXIf , ( png_const_structrp png_ptr , png_inforp info_ptr , png_bytep exif ) ) ; PNG_EXPORT ( 248 , png_uint_32 , png_get_eXIf_1 , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_uint_32 * num_exif , png_bytep * exif ) ) ; PNG_EXPORT ( 249 , void , png_set_eXIf_1 , ( png_const_structrp png_ptr , png_inforp info_ptr , png_uint_32 num_exif , png_bytep exif ) ) ; # endif # ifdef PNG_gAMA_SUPPORTED PNG_FP_EXPORT ( 137 , png_uint_32 , png_get_gAMA , ( png_const_structrp png_ptr , png_const_inforp info_ptr , double * file_gamma ) ) PNG_FIXED_EXPORT ( 138 , png_uint_32 , png_get_gAMA_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_fixed_point * int_file_gamma ) ) # endif # ifdef PNG_gAMA_SUPPORTED PNG_FP_EXPORT ( 139 , void , png_set_gAMA , ( png_const_structrp png_ptr , png_inforp info_ptr , double file_gamma ) ) PNG_FIXED_EXPORT ( 140 , void , png_set_gAMA_fixed , ( png_const_structrp png_ptr , png_inforp info_ptr , png_fixed_point int_file_gamma ) ) # endif # ifdef PNG_hIST_SUPPORTED PNG_EXPORT ( 141 , png_uint_32 , png_get_hIST , ( png_const_structrp png_ptr , png_inforp info_ptr , png_uint_16p * hist ) ) ; PNG_EXPORT ( 142 , void , png_set_hIST , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_uint_16p hist ) ) ; # endif PNG_EXPORT ( 143 , png_uint_32 , png_get_IHDR , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_uint_32 * width , png_uint_32 * height , int * bit_depth , int * color_type , int * interlace_method , int * compression_method , int * filter_method ) ) ; PNG_EXPORT ( 144 , void , png_set_IHDR , ( png_const_structrp png_ptr , png_inforp info_ptr , png_uint_32 width , png_uint_32 height , int bit_depth , int color_type , int interlace_method , int compression_method , int filter_method ) ) ; # ifdef PNG_mDCV_SUPPORTED PNG_FP_EXPORT ( 256 , png_uint_32 , png_get_mDCV , ( png_const_structrp png_ptr , png_const_inforp info_ptr , / * The chromaticities of the mastering display . As cHRM , but independent of * the encoding endpoints in cHRM , or cICP , or iCCP . These values will * always be in the range 0 to 1 . 3107 . * / double * white_x , double * white_y , double * red_x , double * red_y , double * green_x , double * green_y , double * blue_x , double * blue_y , / * Mastering display luminance in cd / m2 ( nits ) . * / double * mastering_display_maximum_luminance , double * mastering_display_minimum_luminance ) ) PNG_FIXED_EXPORT ( 257 , png_uint_32 , png_get_mDCV_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_fixed_point * int_white_x , png_fixed_point * int_white_y , png_fixed_point * int_red_x , png_fixed_point * int_red_y , png_fixed_point * int_green_x , png_fixed_point * int_green_y , png_fixed_point * int_blue_x , png_fixed_point * int_blue_y , / * Mastering display luminance in cd / m2 ( nits ) multiplied ( scaled ) by * 10 , 000 . * / png_uint_32p mastering_display_maximum_luminance_scaled_by_10000 , png_uint_32p mastering_display_minimum_luminance_scaled_by_10000 ) ) # endif # ifdef PNG_mDCV_SUPPORTED PNG_FP_EXPORT ( 258 , void , png_set_mDCV , ( png_const_structrp png_ptr , png_inforp info_ptr , / * The chromaticities of the mastering display . As cHRM , but independent of * the encoding endpoints in cHRM , or cICP , or iCCP . * / double white_x , double white_y , double red_x , double red_y , double green_x , double green_y , double blue_x , double blue_y , / * Mastering display luminance in cd / m2 ( nits ) . * / double mastering_display_maximum_luminance , double mastering_display_minimum_luminance ) ) PNG_FIXED_EXPORT ( 259 , void , png_set_mDCV_fixed , ( png_const_structrp png_ptr , png_inforp info_ptr , / * The admissible range of these values is not the full range of a PNG * fixed point value . Negative values cannot be encoded and the maximum * value is about 1 . 3 * / png_fixed_point int_white_x , png_fixed_point int_white_y , png_fixed_point int_red_x , png_fixed_point int_red_y , png_fixed_point int_green_x , png_fixed_point int_green_y , png_fixed_point int_blue_x , png_fixed_point int_blue_y , / * These are PNG unsigned 4 byte values : 31 - bit unsigned values . The MSB * must be zero . * / png_uint_32 mastering_display_maximum_luminance_scaled_by_10000 , png_uint_32 mastering_display_minimum_luminance_scaled_by_10000 ) ) # endif # ifdef PNG_oFFs_SUPPORTED PNG_EXPORT ( 145 , png_uint_32 , png_get_oFFs , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_int_32 * offset_x , png_int_32 * offset_y , int * unit_type ) ) ; # endif # ifdef PNG_oFFs_SUPPORTED PNG_EXPORT ( 146 , void , png_set_oFFs , ( png_const_structrp png_ptr , png_inforp info_ptr , png_int_32 offset_x , png_int_32 offset_y , int unit_type ) ) ; # endif # ifdef PNG_pCAL_SUPPORTED PNG_EXPORT ( 147 , png_uint_32 , png_get_pCAL , ( png_const_structrp png_ptr , png_inforp info_ptr , png_charp * purpose , png_int_32 * X0 , png_int_32 * X1 , int * type , int * nparams , png_charp * units , png_charpp * params ) ) ; # endif # ifdef PNG_pCAL_SUPPORTED PNG_EXPORT ( 148 , void , png_set_pCAL , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_charp purpose , png_int_32 X0 , png_int_32 X1 , int type , int nparams , png_const_charp units , png_charpp params ) ) ; # endif # ifdef PNG_pHYs_SUPPORTED PNG_EXPORT ( 149 , png_uint_32 , png_get_pHYs , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_uint_32 * res_x , png_uint_32 * res_y , int * unit_type ) ) ; # endif # ifdef PNG_pHYs_SUPPORTED PNG_EXPORT ( 150 , void , png_set_pHYs , ( png_const_structrp png_ptr , png_inforp info_ptr , png_uint_32 res_x , png_uint_32 res_y , int unit_type ) ) ; # endif PNG_EXPORT ( 151 , png_uint_32 , png_get_PLTE , ( png_const_structrp png_ptr , png_inforp info_ptr , png_colorp * palette , int * num_palette ) ) ; PNG_EXPORT ( 152 , void , png_set_PLTE , ( png_structrp png_ptr , png_inforp info_ptr , png_const_colorp palette , int num_palette ) ) ; # ifdef PNG_sBIT_SUPPORTED PNG_EXPORT ( 153 , png_uint_32 , png_get_sBIT , ( png_const_structrp png_ptr , png_inforp info_ptr , png_color_8p * sig_bit ) ) ; # endif # ifdef PNG_sBIT_SUPPORTED PNG_EXPORT ( 154 , void , png_set_sBIT , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_color_8p sig_bit ) ) ; # endif # ifdef PNG_sRGB_SUPPORTED PNG_EXPORT ( 155 , png_uint_32 , png_get_sRGB , ( png_const_structrp png_ptr , png_const_inforp info_ptr , int * file_srgb_intent ) ) ; # endif # ifdef PNG_sRGB_SUPPORTED PNG_EXPORT ( 156 , void , png_set_sRGB , ( png_const_structrp png_ptr , png_inforp info_ptr , int srgb_intent ) ) ; PNG_EXPORT ( 157 , void , png_set_sRGB_gAMA_and_cHRM , ( png_const_structrp png_ptr , png_inforp info_ptr , int srgb_intent ) ) ; # endif # ifdef PNG_iCCP_SUPPORTED PNG_EXPORT ( 158 , png_uint_32 , png_get_iCCP , ( png_const_structrp png_ptr , png_inforp info_ptr , png_charpp name , int * compression_type , png_bytepp profile , png_uint_32 * proflen ) ) ; # endif # ifdef PNG_iCCP_SUPPORTED PNG_EXPORT ( 159 , void , png_set_iCCP , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_charp name , int compression_type , png_const_bytep profile , png_uint_32 proflen ) ) ; # endif # ifdef PNG_sPLT_SUPPORTED PNG_EXPORT ( 160 , int , png_get_sPLT , ( png_const_structrp png_ptr , png_inforp info_ptr , png_sPLT_tpp entries ) ) ; # endif # ifdef PNG_sPLT_SUPPORTED PNG_EXPORT ( 161 , void , png_set_sPLT , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_sPLT_tp entries , int nentries ) ) ; # endif # ifdef PNG_TEXT_SUPPORTED / * png_get_text also returns the number of text chunks in * num_text * / PNG_EXPORT ( 162 , int , png_get_text , ( png_const_structrp png_ptr , png_inforp info_ptr , png_textp * text_ptr , int * num_text ) ) ; # endif / * Note while png_set_text ( ) will accept a structure whose text , * language , and translated keywords are NULL pointers , the structure * returned by png_get_text will always contain regular * zero - terminated C strings . They might be empty strings but * they will never be NULL pointers . * / # ifdef PNG_TEXT_SUPPORTED PNG_EXPORT ( 163 , void , png_set_text , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_textp text_ptr , int num_text ) ) ; # endif # ifdef PNG_tIME_SUPPORTED PNG_EXPORT ( 164 , png_uint_32 , png_get_tIME , ( png_const_structrp png_ptr , png_inforp info_ptr , png_timep * mod_time ) ) ; # endif # ifdef PNG_tIME_SUPPORTED PNG_EXPORT ( 165 , void , png_set_tIME , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_timep mod_time ) ) ; # endif # ifdef PNG_tRNS_SUPPORTED PNG_EXPORT ( 166 , png_uint_32 , png_get_tRNS , ( png_const_structrp png_ptr , png_inforp info_ptr , png_bytep * trans_alpha , int * num_trans , png_color_16p * trans_color ) ) ; # endif # ifdef PNG_tRNS_SUPPORTED PNG_EXPORT ( 167 , void , png_set_tRNS , ( png_structrp png_ptr , png_inforp info_ptr , png_const_bytep trans_alpha , int num_trans , png_const_color_16p trans_color ) ) ; # endif # ifdef PNG_sCAL_SUPPORTED PNG_FP_EXPORT ( 168 , png_uint_32 , png_get_sCAL , ( png_const_structrp png_ptr , png_const_inforp info_ptr , int * unit , double * width , double * height ) ) # if defined ( PNG_FLOATING_ARITHMETIC_SUPPORTED ) | | \ defined ( PNG_FLOATING_POINT_SUPPORTED ) / * NOTE : this API is currently implemented using floating point arithmetic , * consequently it can only be used on systems with floating point support . * In any case the range of values supported by png_fixed_point is small and it * is highly recommended that png_get_sCAL_s be used instead . * / PNG_FIXED_EXPORT ( 214 , png_uint_32 , png_get_sCAL_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr , int * unit , png_fixed_point * width , png_fixed_point * height ) ) # endif PNG_EXPORT ( 169 , png_uint_32 , png_get_sCAL_s , ( png_const_structrp png_ptr , png_const_inforp info_ptr , int * unit , png_charpp swidth , png_charpp sheight ) ) ; PNG_FP_EXPORT ( 170 , void , png_set_sCAL , ( png_const_structrp png_ptr , png_inforp info_ptr , int unit , double width , double height ) ) PNG_FIXED_EXPORT ( 213 , void , png_set_sCAL_fixed , ( png_const_structrp png_ptr , png_inforp info_ptr , int unit , png_fixed_point width , png_fixed_point height ) ) PNG_EXPORT ( 171 , void , png_set_sCAL_s , ( png_const_structrp png_ptr , png_inforp info_ptr , int unit , png_const_charp swidth , png_const_charp sheight ) ) ; # endif / * sCAL * / # ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED / * Provide the default handling for all unknown chunks or , optionally , for * specific unknown chunks . * * NOTE : prior to 1 . 6 . 0 the handling specified for particular chunks on read was * ignored and the default was used , the per - chunk setting only had an effect on * write . If you wish to have chunk - specific handling on read in code that must * work on earlier versions you must use a user chunk callback to specify the * desired handling ( keep or discard . ) * * The ' keep ' parameter is a PNG_HANDLE_CHUNK_ value as listed below . The * parameter is interpreted as follows : * * READ : * PNG_HANDLE_CHUNK_AS_DEFAULT : * Known chunks : do normal libpng processing , do not keep the chunk ( but * see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED ) * Unknown chunks : for a specific chunk use the global default , when used * as the default discard the chunk data . * PNG_HANDLE_CHUNK_NEVER : * Discard the chunk data . * PNG_HANDLE_CHUNK_IF_SAFE : * Keep the chunk data if the chunk is not critical else raise a chunk * error . * PNG_HANDLE_CHUNK_ALWAYS : * Keep the chunk data . * * If the chunk data is saved it can be retrieved using png_get_unknown_chunks , * below . Notice that specifying " AS_DEFAULT " as a global default is equivalent * to specifying " NEVER " , however when " AS_DEFAULT " is used for specific chunks * it simply resets the behavior to the libpng default . * * INTERACTION WITH USER CHUNK CALLBACKS : * The per - chunk handling is always used when there is a png_user_chunk_ptr * callback and the callback returns 0 ; the chunk is then always stored * unless * * it is critical and the per - chunk setting is other than ALWAYS . Notice that * the global default is * not * used in this case . ( In effect the per - chunk * value is incremented to at least IF_SAFE . ) * * IMPORTANT NOTE : this behavior will change in libpng 1 . 7 - the global and * per - chunk defaults will be honored . If you want to preserve the current * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE * as the default - if you don ' t do this libpng 1 . 6 will issue a warning . * * If you want unhandled unknown chunks to be discarded in libpng 1 . 6 and * earlier simply return ' 1 ' ( handled ) . * * PNG_HANDLE_AS_UNKNOWN_SUPPORTED : * If this is * not * set known chunks will always be handled by libpng and * will never be stored in the unknown chunk list . Known chunks listed to * png_set_keep_unknown_chunks will have no effect . If it is set then known * chunks listed with a keep other than AS_DEFAULT will * never * be processed * by libpng , in addition critical chunks must either be processed by the * callback or saved . * * The IHDR and IEND chunks must not be listed . Because this turns off the * default handling for chunks that would otherwise be recognized the * behavior of libpng transformations may well become incorrect ! * * WRITE : * When writing chunks the options only apply to the chunks specified by * png_set_unknown_chunks ( below ) , libpng will * always * write known chunks * required by png_set_ calls and will always write the core critical chunks * ( as required for PLTE ) . * * Each chunk in the png_set_unknown_chunks list is looked up in the * png_set_keep_unknown_chunks list to find the keep setting , this is then * interpreted as follows : * * PNG_HANDLE_CHUNK_AS_DEFAULT : * Write safe - to - copy chunks and write other chunks if the global * default is set to _ ALWAYS , otherwise don ' t write this chunk . * PNG_HANDLE_CHUNK_NEVER : * Do not write the chunk . * PNG_HANDLE_CHUNK_IF_SAFE : * Write the chunk if it is safe - to - copy , otherwise do not write it . * PNG_HANDLE_CHUNK_ALWAYS : * Write the chunk . * * Note that the default behavior is effectively the opposite of the read case - * in read unknown chunks are not stored by default , in write they are written * by default . Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different * - on write the safe - to - copy bit is checked , on read the critical bit is * checked and on read if the chunk is critical an error will be raised . * * num_chunks : * = = = = = = = = = = = * If num_chunks is positive , then the " keep " parameter specifies the manner * for handling only those chunks appearing in the chunk_list array , * otherwise the chunk list array is ignored . * * If num_chunks is 0 the " keep " parameter specifies the default behavior for * unknown chunks , as described above . * * If num_chunks is negative , then the " keep " parameter specifies the manner * for handling all unknown chunks plus all chunks recognized by libpng * except for the IHDR , PLTE , tRNS , IDAT , and IEND chunks ( which continue to * be processed by libpng . * / # ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED PNG_EXPORT ( 172 , void , png_set_keep_unknown_chunks , ( png_structrp png_ptr , int keep , png_const_bytep chunk_list , int num_chunks ) ) ; # endif / * HANDLE_AS_UNKNOWN * / / * The " keep " PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned ; * the result is therefore true ( non - zero ) if special handling is required , * false for the default handling . * / PNG_EXPORT ( 173 , int , png_handle_as_unknown , ( png_const_structrp png_ptr , png_const_bytep chunk_name ) ) ; # endif / * SET_UNKNOWN_CHUNKS * / # ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED PNG_EXPORT ( 174 , void , png_set_unknown_chunks , ( png_const_structrp png_ptr , png_inforp info_ptr , png_const_unknown_chunkp unknowns , int num_unknowns ) ) ; / * NOTE : prior to 1 . 6 . 0 this routine set the ' location ' field of the added * unknowns to the location currently stored in the png_struct . This is * invariably the wrong value on write . To fix this call the following API * for each chunk in the list with the correct location . If you know your * code won ' t be compiled on earlier versions you can rely on * png_set_unknown_chunks ( write - ptr , png_get_unknown_chunks ( read - ptr ) ) doing * the correct thing . * / PNG_EXPORT ( 175 , void , png_set_unknown_chunk_location , ( png_const_structrp png_ptr , png_inforp info_ptr , int chunk , int location ) ) ; PNG_EXPORT ( 176 , int , png_get_unknown_chunks , ( png_const_structrp png_ptr , png_inforp info_ptr , png_unknown_chunkpp entries ) ) ; # endif / * Png_free_data ( ) will turn off the " valid " flag for anything it frees . * If you need to turn it off for a chunk that your application has freed , * you can use png_set_invalid ( png_ptr , info_ptr , PNG_INFO_CHNK ) ; * / PNG_EXPORT ( 177 , void , png_set_invalid , ( png_const_structrp png_ptr , png_inforp info_ptr , int mask ) ) ; # ifdef PNG_INFO_IMAGE_SUPPORTED / * The " params " pointer is currently not used and is for future expansion . * / # ifdef PNG_SEQUENTIAL_READ_SUPPORTED PNG_EXPORT ( 178 , void , png_read_png , ( png_structrp png_ptr , png_inforp info_ptr , int transforms , png_voidp params ) ) ; # endif # ifdef PNG_WRITE_SUPPORTED PNG_EXPORT ( 179 , void , png_write_png , ( png_structrp png_ptr , png_inforp info_ptr , int transforms , png_voidp params ) ) ; # endif # endif PNG_EXPORT ( 180 , png_const_charp , png_get_copyright , ( png_const_structrp png_ptr ) ) ; PNG_EXPORT ( 181 , png_const_charp , png_get_header_ver , ( png_const_structrp png_ptr ) ) ; PNG_EXPORT ( 182 , png_const_charp , png_get_header_version , ( png_const_structrp png_ptr ) ) ; PNG_EXPORT ( 183 , png_const_charp , png_get_libpng_ver , ( png_const_structrp png_ptr ) ) ; # ifdef PNG_MNG_FEATURES_SUPPORTED PNG_EXPORT ( 184 , png_uint_32 , png_permit_mng_features , ( png_structrp png_ptr , png_uint_32 mng_features_permitted ) ) ; # endif / * For use in png_set_keep_unknown , added to version 1 . 2 . 6 * / # define PNG_HANDLE_CHUNK_AS_DEFAULT 0 # define PNG_HANDLE_CHUNK_NEVER 1 # define PNG_HANDLE_CHUNK_IF_SAFE 2 # define PNG_HANDLE_CHUNK_ALWAYS 3 # define PNG_HANDLE_CHUNK_LAST 4 / * Strip the prepended error numbers ( " # nnn " ) from error and warning * messages before passing them to the error or warning handler . * / # ifdef PNG_ERROR_NUMBERS_SUPPORTED PNG_EXPORT ( 185 , void , png_set_strip_error_numbers , ( png_structrp png_ptr , png_uint_32 strip_mode ) ) ; # endif / * Added in libpng - 1 . 2 . 6 * / # ifdef PNG_SET_USER_LIMITS_SUPPORTED PNG_EXPORT ( 186 , void , png_set_user_limits , ( png_structrp png_ptr , png_uint_32 user_width_max , png_uint_32 user_height_max ) ) ; PNG_EXPORT ( 187 , png_uint_32 , png_get_user_width_max , ( png_const_structrp png_ptr ) ) ; PNG_EXPORT ( 188 , png_uint_32 , png_get_user_height_max , ( png_const_structrp png_ptr ) ) ; / * Added in libpng - 1 . 4 . 0 * / PNG_EXPORT ( 189 , void , png_set_chunk_cache_max , ( png_structrp png_ptr , png_uint_32 user_chunk_cache_max ) ) ; PNG_EXPORT ( 190 , png_uint_32 , png_get_chunk_cache_max , ( png_const_structrp png_ptr ) ) ; / * Added in libpng - 1 . 4 . 1 * / PNG_EXPORT ( 191 , void , png_set_chunk_malloc_max , ( png_structrp png_ptr , png_alloc_size_t user_chunk_cache_max ) ) ; PNG_EXPORT ( 192 , png_alloc_size_t , png_get_chunk_malloc_max , ( png_const_structrp png_ptr ) ) ; # endif # if defined ( PNG_INCH_CONVERSIONS_SUPPORTED ) PNG_EXPORT ( 193 , png_uint_32 , png_get_pixels_per_inch , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 194 , png_uint_32 , png_get_x_pixels_per_inch , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_EXPORT ( 195 , png_uint_32 , png_get_y_pixels_per_inch , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) ; PNG_FP_EXPORT ( 196 , float , png_get_x_offset_inches , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) # ifdef PNG_FIXED_POINT_SUPPORTED / * otherwise not implemented . * / PNG_FIXED_EXPORT ( 211 , png_fixed_point , png_get_x_offset_inches_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) # endif PNG_FP_EXPORT ( 197 , float , png_get_y_offset_inches , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) # ifdef PNG_FIXED_POINT_SUPPORTED / * otherwise not implemented . * / PNG_FIXED_EXPORT ( 212 , png_fixed_point , png_get_y_offset_inches_fixed , ( png_const_structrp png_ptr , png_const_inforp info_ptr ) ) # endif # ifdef PNG_pHYs_SUPPORTED PNG_EXPORT ( 198 , png_uint_32 , png_get_pHYs_dpi , ( png_const_structrp png_ptr , png_const_inforp info_ptr , png_uint_32 * res_x , png_uint_32 * res_y , int * unit_type ) ) ; # endif / * pHYs * / # endif / * INCH_CONVERSIONS * / / * Added in libpng - 1 . 4 . 0 * / # ifdef PNG_IO_STATE_SUPPORTED PNG_EXPORT ( 199 , png_uint_32 , png_get_io_state , ( png_const_structrp png_ptr ) ) ; / * Removed from libpng 1 . 6 ; use png_get_io_chunk_type . * / PNG_REMOVED ( 200 , png_const_bytep , png_get_io_chunk_name , ( png_structrp png_ptr ) , PNG_DEPRECATED ) PNG_EXPORT ( 216 , png_uint_32 , png_get_io_chunk_type , ( png_const_structrp png_ptr ) ) ; / * The flags returned by png_get_io_state ( ) are the following : * / # define PNG_IO_NONE 0 x0000 / * no I / O at this moment * / # define PNG_IO_READING 0 x0001 / * currently reading * / # define PNG_IO_WRITING 0 x0002 / * currently writing * / # define PNG_IO_SIGNATURE 0 x0010 / * currently at the file signature * / # define PNG_IO_CHUNK_HDR 0 x0020 / * currently at the chunk header * / # define PNG_IO_CHUNK_DATA 0 x0040 / * currently at the chunk data * / # define PNG_IO_CHUNK_CRC 0 x0080 / * currently at the chunk crc * / # define PNG_IO_MASK_OP 0 x000f / * current operation : reading / writing * / # define PNG_IO_MASK_LOC 0 x00f0 / * current location : sig / hdr / data / crc * / # endif / * IO_STATE * / / * Interlace support . The following macros are always defined so that if * libpng interlace handling is turned off the macros may be used to handle * interlaced images within the application . * / # define PNG_INTERLACE_ADAM7_PASSES 7 / * Two macros to return the first row and first column of the original , * full , image which appears in a given pass . ' pass ' is in the range 0 * to 6 and the result is in the range 0 to 7 . * / # define PNG_PASS_START_ROW ( pass ) ( ( ( 1 & ~ ( pass ) ) < < ( 3 - ( ( pass ) > > 1 ) ) ) & 7 ) # define PNG_PASS_START_COL ( pass ) ( ( ( 1 & ( pass ) ) < < ( 3 - ( ( ( pass ) + 1 ) > > 1 ) ) ) & 7 ) / * A macro to return the offset between pixels in the output row for a pair of * pixels in the input - effectively the inverse of the ' COL_SHIFT ' macro that * follows . Note that ROW_OFFSET is the offset from one row to the next whereas * COL_OFFSET is from one column to the next , within a row . * / # define PNG_PASS_ROW_OFFSET ( pass ) ( ( pass ) > 2 ? ( 8 > > ( ( ( pass ) - 1 ) > > 1 ) ) : 8 ) # define PNG_PASS_COL_OFFSET ( pass ) ( 1 < < ( ( 7 - ( pass ) ) > > 1 ) ) / * Two macros to help evaluate the number of rows or columns in each * pass . This is expressed as a shift - effectively log2 of the number or * rows or columns in each 8 x8 tile of the original image . * / # define PNG_PASS_ROW_SHIFT ( pass ) ( ( pass ) > 2 ? ( 8 - ( pass ) ) > > 1 : 3 ) # define PNG_PASS_COL_SHIFT ( pass ) ( ( pass ) > 1 ? ( 7 - ( pass ) ) > > 1 : 3 ) / * Hence two macros to determine the number of rows or columns in a given * pass of an image given its height or width . In fact these macros may * return non - zero even though the sub - image is empty , because the other * dimension may be empty for a small image . * / # define PNG_PASS_ROWS ( height , pass ) ( ( ( height ) + ( ( ( 1 < < PNG_PASS_ROW_SHIFT ( pass ) ) \ - 1 ) - PNG_PASS_START_ROW ( pass ) ) ) > > PNG_PASS_ROW_SHIFT ( pass ) ) # define PNG_PASS_COLS ( width , pass ) ( ( ( width ) + ( ( ( 1 < < PNG_PASS_COL_SHIFT ( pass ) ) \ - 1 ) - PNG_PASS_START_COL ( pass ) ) ) > > PNG_PASS_COL_SHIFT ( pass ) ) / * For the reader row callbacks ( both progressive and sequential ) it is * necessary to find the row in the output image given a row in an interlaced * image , so two more macros : * / # define PNG_ROW_FROM_PASS_ROW ( y_in , pass ) \ ( ( ( y_in ) < < PNG_PASS_ROW_SHIFT ( pass ) ) + PNG_PASS_START_ROW ( pass ) ) # define PNG_COL_FROM_PASS_COL ( x_in , pass ) \ ( ( ( x_in ) < < PNG_PASS_COL_SHIFT ( pass ) ) + PNG_PASS_START_COL ( pass ) ) / * Two macros which return a boolean ( 0 or 1 ) saying whether the given row * or column is in a particular pass . These use a common utility macro that * returns a mask for a given pass - the offset ' off ' selects the row or * column version . The mask has the appropriate bit set for each column in * the tile . * / # define PNG_PASS_MASK ( pass , off ) ( \ ( ( 0 x110145AF > > ( ( ( 7 - ( off ) ) - ( pass ) ) < < 2 ) ) & 0 xF ) | \ ( ( 0 x01145AF0 > > ( ( ( 7 - ( off ) ) - ( pass ) ) < < 2 ) ) & 0 xF0 ) ) # define PNG_ROW_IN_INTERLACE_PASS ( y , pass ) \ ( ( PNG_PASS_MASK ( pass , 0 ) > > ( ( y ) & 7 ) ) & 1 ) # define PNG_COL_IN_INTERLACE_PASS ( x , pass ) \ ( ( PNG_PASS_MASK ( pass , 1 ) > > ( ( x ) & 7 ) ) & 1 ) # ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED / * With these routines we avoid an integer divide , which will be slower on * most machines . However , it does take more operations than the corresponding * divide method , so it may be slower on a few RISC systems . There are two * shifts ( by 8 or 16 bits ) and an addition , versus a single integer divide . * * Note that the rounding factors are NOT supposed to be the same ! 128 and * 32768 are correct for the NODIV code ; 127 and 32767 are correct for the * standard method . * * [ Optimized code by Greg Roelofs and Mark Adler . . . blame us for bugs . : - ) ] * / / * fg and bg should be in ` gamma 1 . 0 ' space ; alpha is the opacity * / # define png_composite ( composite , fg , alpha , bg ) \ { \ png_uint_16 temp = ( png_uint_16 ) ( ( png_uint_16 ) ( fg ) \ * ( png_uint_16 ) ( alpha ) \ + ( png_uint_16 ) ( bg ) * ( png_uint_16 ) ( 255 \ - ( png_uint_16 ) ( alpha ) ) + 128 ) ; \ ( composite ) = ( png_byte ) ( ( ( temp + ( temp > > 8 ) ) > > 8 ) & 0 xff ) ; \ } # define png_composite_16 ( composite , fg , alpha , bg ) \ { \ png_uint_32 temp = ( png_uint_32 ) ( ( png_uint_32 ) ( fg ) \ * ( png_uint_32 ) ( alpha ) \ + ( png_uint_32 ) ( bg ) * ( 65535 \ - ( png_uint_32 ) ( alpha ) ) + 32768 ) ; \ ( composite ) = ( png_uint_16 ) ( 0 xffff & ( ( temp + ( temp > > 16 ) ) > > 16 ) ) ; \ } # else / * Standard method using integer division * / # define png_composite ( composite , fg , alpha , bg ) \ ( composite ) = \ ( png_byte ) ( 0 xff & ( ( ( png_uint_16 ) ( fg ) * ( png_uint_16 ) ( alpha ) + \ ( png_uint_16 ) ( bg ) * ( png_uint_16 ) ( 255 - ( png_uint_16 ) ( alpha ) ) + \ 127 ) / 255 ) ) # define png_composite_16 ( composite , fg , alpha , bg ) \ ( composite ) = \ ( png_uint_16 ) ( 0 xffff & ( ( ( png_uint_32 ) ( fg ) * ( png_uint_32 ) ( alpha ) + \ ( png_uint_32 ) ( bg ) * ( png_uint_32 ) ( 65535 - ( png_uint_32 ) ( alpha ) ) + \ 32767 ) / 65535 ) ) # endif / * READ_COMPOSITE_NODIV * / # ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED PNG_EXPORT ( 201 , png_uint_32 , png_get_uint_32 , ( png_const_bytep buf ) ) ; PNG_EXPORT ( 202 , png_uint_16 , png_get_uint_16 , ( png_const_bytep buf ) ) ; PNG_EXPORT ( 203 , png_int_32 , png_get_int_32 , ( png_const_bytep buf ) ) ; # endif PNG_EXPORT ( 204 , png_uint_32 , png_get_uint_31 , ( png_const_structrp png_ptr , png_const_bytep buf ) ) ; / * No png_get_int_16 - - may be added if there ' s a real need for it . * / / * Place a 32 - bit number into a buffer in PNG byte order ( big - endian ) . * / # ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED PNG_EXPORT ( 205 , void , png_save_uint_32 , ( png_bytep buf , png_uint_32 i ) ) ; # endif # ifdef PNG_SAVE_INT_32_SUPPORTED PNG_EXPORT ( 206 , void , png_save_int_32 , ( png_bytep buf , png_int_32 i ) ) ; # endif / * Place a 16 - bit number into a buffer in PNG byte order . * The parameter is declared unsigned int , not png_uint_16 , * just to avoid potential problems on pre - ANSI C compilers . * / # ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED PNG_EXPORT ( 207 , void , png_save_uint_16 , ( png_bytep buf , unsigned int i ) ) ; / * No png_save_int_16 - - may be added if there ' s a real need for it . * / # endif # ifdef PNG_USE_READ_MACROS / * Inline macros to do direct reads of bytes from the input buffer . * The png_get_int_32 ( ) routine assumes we are using two ' s complement * format for negative values , which is almost certainly true . * / # define PNG_get_uint_32 ( buf ) \ ( ( ( png_uint_32 ) ( * ( buf ) ) < < 24 ) + \ ( ( png_uint_32 ) ( * ( ( buf ) + 1 ) ) < < 16 ) + \ ( ( png_uint_32 ) ( * ( ( buf ) + 2 ) ) < < 8 ) + \ ( ( png_uint_32 ) ( * ( ( buf ) + 3 ) ) ) ) / * From libpng - 1 . 4 . 0 until 1 . 4 . 4 , the png_get_uint_16 macro ( but not the * function ) incorrectly returned a value of type png_uint_32 . * / # define PNG_get_uint_16 ( buf ) \ ( ( png_uint_16 ) \ ( ( ( unsigned int ) ( * ( buf ) ) < < 8 ) + \ ( ( unsigned int ) ( * ( ( buf ) + 1 ) ) ) ) ) # define PNG_get_int_32 ( buf ) \ ( ( png_int_32 ) ( ( * ( buf ) & 0 x80 ) \ ? - ( ( png_int_32 ) ( ( ( png_get_uint_32 ( buf ) ^ 0 xffffffffU ) + 1 U ) & 0 x7fffffffU ) ) \ : ( png_int_32 ) png_get_uint_32 ( buf ) ) ) / * If PNG_PREFIX is defined the same thing as below happens in pnglibconf . h , * but defining a macro name prefixed with PNG_PREFIX . * / # ifndef PNG_PREFIX # define png_get_uint_32 ( buf ) PNG_get_uint_32 ( buf ) # define png_get_uint_16 ( buf ) PNG_get_uint_16 ( buf ) # define png_get_int_32 ( buf ) PNG_get_int_32 ( buf ) # endif # else # ifdef PNG_PREFIX / * No macros ; revert to the ( redefined ) function * / # define PNG_get_uint_32 ( png_get_uint_32 ) # define PNG_get_uint_16 ( png_get_uint_16 ) # define PNG_get_int_32 ( png_get_int_32 ) # endif # endif # ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED PNG_EXPORT ( 242 , void , png_set_check_for_invalid_index , ( png_structrp png_ptr , int allowed ) ) ; # ifdef PNG_GET_PALETTE_MAX_SUPPORTED PNG_EXPORT ( 243 , int , png_get_palette_max , ( png_const_structp png_ptr , png_const_infop info_ptr ) ) ; # endif # endif / * CHECK_FOR_INVALID_INDEX * / / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Section 5 : SIMPLIFIED API * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Please read the documentation in libpng - manual . txt ( TODO : write said * documentation ) if you don ' t understand what follows . * * The simplified API hides the details of both libpng and the PNG file format * itself . It allows PNG files to be read into a very limited number of * in - memory bitmap formats or to be written from the same formats . If these * formats do not accommodate your needs then you can , and should , use the more * sophisticated APIs above - these support a wide variety of in - memory formats * and a wide variety of sophisticated transformations to those formats as well * as a wide variety of APIs to manipulate ancillary information . * * To read a PNG file using the simplified API : * * 1 ) Declare a ' png_image ' structure ( see below ) on the stack , set the * version field to PNG_IMAGE_VERSION and the ' opaque ' pointer to NULL * ( this is REQUIRED , your program may crash if you don ' t do it . ) * 2 ) Call the appropriate png_image_begin_read . . . function . * 3 ) Set the png_image ' format ' member to the required sample format . * 4 ) Allocate a buffer for the image and , if required , the color - map . * 5 ) Call png_image_finish_read to read the image and , if required , the * color - map into your buffers . * * There are no restrictions on the format of the PNG input itself ; all valid * color types , bit depths , and interlace methods are acceptable , and the * input image is transformed as necessary to the requested in - memory format * during the png_image_finish_read ( ) step . The only caveat is that if you * request a color - mapped image from a PNG that is full - color or makes * complex use of an alpha channel the transformation is extremely lossy and the * result may look terrible . * * To write a PNG file using the simplified API : * * 1 ) Declare a ' png_image ' structure on the stack and memset ( ) it to all zero . * 2 ) Initialize the members of the structure that describe the image , setting * the ' format ' member to the format of the image samples . * 3 ) Call the appropriate png_image_write . . . function with a pointer to the * image and , if necessary , the color - map to write the PNG data . * * png_image is a structure that describes the in - memory format of an image * when it is being read or defines the in - memory format of an image that you * need to write : * / # if defined ( PNG_SIMPLIFIED_READ_SUPPORTED ) | | \ defined ( PNG_SIMPLIFIED_WRITE_SUPPORTED ) # define PNG_IMAGE_VERSION 1 typedef struct png_control * png_controlp ; typedef struct { png_controlp opaque ; / * Initialize to NULL , free with png_image_free * / png_uint_32 version ; / * Set to PNG_IMAGE_VERSION * / png_uint_32 width ; / * Image width in pixels ( columns ) * / png_uint_32 height ; / * Image height in pixels ( rows ) * / png_uint_32 format ; / * Image format as defined below * / png_uint_32 flags ; / * A bit mask containing informational flags * / png_uint_32 colormap_entries ; / * Number of entries in the color - map * / / * In the event of an error or warning the following field will be set to a * non - zero value and the ' message ' field will contain a ' \ 0 ' terminated * string with the libpng error or warning message . If both warnings and * an error were encountered , only the error is recorded . If there * are multiple warnings , only the first one is recorded . * * The upper 30 bits of this value are reserved , the low two bits contain * a value as follows : * / # define PNG_IMAGE_WARNING 1 # define PNG_IMAGE_ERROR 2 / * * The result is a two - bit code such that a value more than 1 indicates * a failure in the API just called : * * 0 - no warning or error * 1 - warning * 2 - error * 3 - error preceded by warning * / # define PNG_IMAGE_FAILED ( png_cntrl ) ( ( ( ( png_cntrl ) . warning_or_error ) & 0 x03 ) > 1 ) png_uint_32 warning_or_error ; char message [ 64 ] ; } png_image , * png_imagep ; / * The samples of the image have one to four channels whose components have * original values in the range 0 to 1 . 0 : * * 1 : A single gray or luminance channel ( G ) . * 2 : A gray / luminance channel and an alpha channel ( GA ) . * 3 : Three red , green , blue color channels ( RGB ) . * 4 : Three color channels and an alpha channel ( RGBA ) . * * The components are encoded in one of two ways : * * a ) As a small integer , value 0 . . 255 , contained in a single byte . For the * alpha channel the original value is simply value / 255 . For the color or * luminance channels the value is encoded according to the sRGB specification * and matches the 8 - bit format expected by typical display devices . * * The color / gray channels are not scaled ( pre - multiplied ) by the alpha * channel and are suitable for passing to color management software . * * b ) As a value in the range 0 . . 65535 , contained in a 2 - byte integer . All * channels can be converted to the original value by dividing by 65535 ; all * channels are linear . Color channels use the RGB encoding ( RGB end - points ) of * the sRGB specification . This encoding is identified by the * PNG_FORMAT_FLAG_LINEAR flag below . * * When the simplified API needs to convert between sRGB and linear colorspaces , * the actual sRGB transfer curve defined in the sRGB specification ( see the * article at < https : / / en . wikipedia . org / wiki / SRGB > ) is used , not the gamma = 1 / 2 . 2 * approximation used elsewhere in libpng . * * When an alpha channel is present it is expected to denote pixel coverage * of the color or luminance channels and is returned as an associated alpha * channel : the color / gray channels are scaled ( pre - multiplied ) by the alpha * value . * * The samples are either contained directly in the image data , between 1 and 8 * bytes per pixel according to the encoding , or are held in a color - map indexed * by bytes in the image data . In the case of a color - map the color - map entries * are individual samples , encoded as above , and the image data has one byte per * pixel to select the relevant sample from the color - map . * / / * PNG_FORMAT_ * * * # defines to be used in png_image : : format . Each # define identifies a * particular layout of sample data and , if present , alpha values . There are * separate defines for each of the two component encodings . * * A format is built up using single bit flag values . All combinations are * valid . Formats can be built up from the flag values or you can use one of * the predefined values below . When testing formats always use the FORMAT_FLAG * macros to test for individual features - future versions of the library may * add new flags . * * When reading or writing color - mapped images the format should be set to the * format of the entries in the color - map then png_image_ { read , write } _ colormap * called to read or write the color - map and set the format correctly for the * image data . Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly ! * * NOTE : libpng can be built with particular features disabled . If you see * compiler errors because the definition of one of the following flags has been * compiled out it is because libpng does not have the required support . It is * possible , however , for the libpng configuration to enable the format on just * read or just write ; in that case you may see an error at run time . You can * guard against this by checking for the definition of the appropriate * " _ SUPPORTED " macro , one of : * * PNG_SIMPLIFIED_ { READ , WRITE } _ { BGR , AFIRST } _ SUPPORTED * / # define PNG_FORMAT_FLAG_ALPHA 0 x01U / * format with an alpha channel * / # define PNG_FORMAT_FLAG_COLOR 0 x02U / * color format : otherwise grayscale * / # define PNG_FORMAT_FLAG_LINEAR 0 x04U / * 2 - byte channels else 1 - byte * / # define PNG_FORMAT_FLAG_COLORMAP 0 x08U / * image data is color - mapped * / # ifdef PNG_FORMAT_BGR_SUPPORTED # define PNG_FORMAT_FLAG_BGR 0 x10U / * BGR colors , else order is RGB * / # endif # ifdef PNG_FORMAT_AFIRST_SUPPORTED # define PNG_FORMAT_FLAG_AFIRST 0 x20U / * alpha channel comes first * / # endif # define PNG_FORMAT_FLAG_ASSOCIATED_ALPHA 0 x40U / * alpha channel is associated * / / * Commonly used formats have predefined macros . * * First the single byte ( sRGB ) formats : * / # define PNG_FORMAT_GRAY 0 # define PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA # define PNG_FORMAT_AG ( PNG_FORMAT_GA | PNG_FORMAT_FLAG_AFIRST ) # define PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR # define PNG_FORMAT_BGR ( PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_BGR ) # define PNG_FORMAT_RGBA ( PNG_FORMAT_RGB | PNG_FORMAT_FLAG_ALPHA ) # define PNG_FORMAT_ARGB ( PNG_FORMAT_RGBA | PNG_FORMAT_FLAG_AFIRST ) # define PNG_FORMAT_BGRA ( PNG_FORMAT_BGR | PNG_FORMAT_FLAG_ALPHA ) # define PNG_FORMAT_ABGR ( PNG_FORMAT_BGRA | PNG_FORMAT_FLAG_AFIRST ) / * Then the linear 2 - byte formats . When naming these " Y " is used to * indicate a luminance ( gray ) channel . * / # define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR # define PNG_FORMAT_LINEAR_Y_ALPHA ( PNG_FORMAT_FLAG_LINEAR | PNG_FORMAT_FLAG_ALPHA ) # define PNG_FORMAT_LINEAR_RGB ( PNG_FORMAT_FLAG_LINEAR | PNG_FORMAT_FLAG_COLOR ) # define PNG_FORMAT_LINEAR_RGB_ALPHA \ ( PNG_FORMAT_FLAG_LINEAR | PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_ALPHA ) / * With color - mapped formats the image data is one byte for each pixel , the byte * is an index into the color - map which is formatted as above . To obtain a * color - mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP * to one of the above definitions , or you can use one of the definitions below . * / # define PNG_FORMAT_RGB_COLORMAP ( PNG_FORMAT_RGB | PNG_FORMAT_FLAG_COLORMAP ) # define PNG_FORMAT_BGR_COLORMAP ( PNG_FORMAT_BGR | PNG_FORMAT_FLAG_COLORMAP ) # define PNG_FORMAT_RGBA_COLORMAP ( PNG_FORMAT_RGBA | PNG_FORMAT_FLAG_COLORMAP ) # define PNG_FORMAT_ARGB_COLORMAP ( PNG_FORMAT_ARGB | PNG_FORMAT_FLAG_COLORMAP ) # define PNG_FORMAT_BGRA_COLORMAP ( PNG_FORMAT_BGRA | PNG_FORMAT_FLAG_COLORMAP ) # define PNG_FORMAT_ABGR_COLORMAP ( PNG_FORMAT_ABGR | PNG_FORMAT_FLAG_COLORMAP ) / * PNG_IMAGE macros * * These are convenience macros to derive information from a png_image * structure . The PNG_IMAGE_SAMPLE_ macros return values appropriate to the * actual image sample values - either the entries in the color - map or the * pixels in the image . The PNG_IMAGE_PIXEL_ macros return corresponding values * for the pixels and will always return 1 for color - mapped formats . The * remaining macros return information about the rows in the image and the * complete image . * * NOTE : All the macros that take a png_image : : format parameter are compile time * constants if the format parameter is , itself , a constant . Therefore these * macros can be used in array declarations and case labels where required . * Similarly the macros are also pre - processor constants ( sizeof is not used ) so * they can be used in # if tests . * * First the information about the samples . * / # define PNG_IMAGE_SAMPLE_CHANNELS ( fmt ) \ ( ( ( fmt ) & ( PNG_FORMAT_FLAG_COLOR | PNG_FORMAT_FLAG_ALPHA ) ) + 1 ) / * Return the total number of channels in a given format : 1 . . 4 * / # define PNG_IMAGE_SAMPLE_COMPONENT_SIZE ( fmt ) \ ( ( ( ( fmt ) & PNG_FORMAT_FLAG_LINEAR ) > > 2 ) + 1 ) / * Return the size in bytes of a single component of a pixel or color - map * entry ( as appropriate ) in the image : 1 or 2 . * / # define PNG_IMAGE_SAMPLE_SIZE ( fmt ) \ ( PNG_IMAGE_SAMPLE_CHANNELS ( fmt ) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE ( fmt ) ) / * This is the size of the sample data for one sample . If the image is * color - mapped it is the size of one color - map entry ( and image pixels are * one byte in size ) , otherwise it is the size of one image pixel . * / # define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS ( fmt ) \ ( PNG_IMAGE_SAMPLE_CHANNELS ( fmt ) * 256 ) / * The maximum size of the color - map required by the format expressed in a * count of components . This can be used to compile - time allocate a * color - map : * * png_uint_16 colormap [ PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS ( linear_fmt ) ] ; * * png_byte colormap [ PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS ( sRGB_fmt ) ] ; * * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the * information from one of the png_image_begin_read_ APIs and dynamically * allocate the required memory . * / / * Corresponding information about the pixels * / # define PNG_IMAGE_PIXEL_ ( test , fmt ) \ ( ( ( fmt ) & PNG_FORMAT_FLAG_COLORMAP ) ? 1 : test ( fmt ) ) # define PNG_IMAGE_PIXEL_CHANNELS ( fmt ) \ PNG_IMAGE_PIXEL_ ( PNG_IMAGE_SAMPLE_CHANNELS , fmt ) / * The number of separate channels ( components ) in a pixel ; 1 for a * color - mapped image . * / # define PNG_IMAGE_PIXEL_COMPONENT_SIZE ( fmt ) \ PNG_IMAGE_PIXEL_ ( PNG_IMAGE_SAMPLE_COMPONENT_SIZE , fmt ) / * The size , in bytes , of each component in a pixel ; 1 for a color - mapped * image . * / # define PNG_IMAGE_PIXEL_SIZE ( fmt ) PNG_IMAGE_PIXEL_ ( PNG_IMAGE_SAMPLE_SIZE , fmt ) / * The size , in bytes , of a complete pixel ; 1 for a color - mapped image . * / / * Information about the whole row , or whole image * / # define PNG_IMAGE_ROW_STRIDE ( image ) \ ( PNG_IMAGE_PIXEL_CHANNELS ( ( image ) . format ) * ( image ) . width ) / * Return the total number of components in a single row of the image ; this * is the minimum ' row stride ' , the minimum count of components between each * row . For a color - mapped image this is the minimum number of bytes in a * row . * * WARNING : this macro overflows for some images with more than one component * and very large image widths . libpng will refuse to process an image where * this macro would overflow . * / # define PNG_IMAGE_BUFFER_SIZE ( image , row_stride ) \ ( PNG_IMAGE_PIXEL_COMPONENT_SIZE ( ( image ) . format ) * ( image ) . height * ( row_stride ) ) / * Return the size , in bytes , of an image buffer given a png_image and a row * stride - the number of components to leave space for in each row . * * WARNING : this macro overflows a 32 - bit integer for some large PNG images , * libpng will refuse to process an image where such an overflow would occur . * / # define PNG_IMAGE_SIZE ( image ) \ PNG_IMAGE_BUFFER_SIZE ( image , PNG_IMAGE_ROW_STRIDE ( image ) ) / * Return the size , in bytes , of the image in memory given just a png_image ; * the row stride is the minimum stride required for the image . * / # define PNG_IMAGE_COLORMAP_SIZE ( image ) \ ( PNG_IMAGE_SAMPLE_SIZE ( ( image ) . format ) * ( image ) . colormap_entries ) / * Return the size , in bytes , of the color - map of this image . If the image * format is not a color - map format this will return a size sufficient for * 256 entries in the given format ; check PNG_FORMAT_FLAG_COLORMAP if * you don ' t want to allocate a color - map in this case . * / / * PNG_IMAGE_FLAG_ * * * Flags containing additional information about the image are held in the * ' flags ' field of png_image . * / # define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0 x01 / * This indicates that the RGB values of the in - memory bitmap do not * correspond to the red , green and blue end - points defined by sRGB . * / # define PNG_IMAGE_FLAG_FAST 0 x02 / * On write emphasise speed over compression ; the resultant PNG file will be * larger but will be produced significantly faster , particular for large * images . Do not use this option for images which will be distributed , only * used it when producing intermediate files that will be read back in * repeatedly . For a typical 24 - bit image the option will double the read * speed at the cost of increasing the image size by 25 % , however for many * more compressible images the PNG file can be 10 times larger with only a * slight speed gain . * / # define PNG_IMAGE_FLAG_16BIT_sRGB 0 x04 / * On read if the image is a 16 - bit per component image and there is no gAMA * or sRGB chunk assume that the components are sRGB encoded . Notice that * images output by the simplified API always have gamma information ; setting * this flag only affects the interpretation of 16 - bit images from an * external source . It is recommended that the application expose this flag * to the user ; the user can normally easily recognize the difference between * linear and sRGB encoding . This flag has no effect on write - the data * passed to the write APIs must have the correct encoding ( as defined * above . ) * * If the flag is not set ( the default ) input 16 - bit per component data is * assumed to be linear . * * NOTE : the flag can only be set after the png_image_begin_read_ call , * because that call initializes the ' flags ' field . * / # ifdef PNG_SIMPLIFIED_READ_SUPPORTED / * READ APIs * - - - - - - - - - * * The png_image passed to the read APIs must have been initialized by setting * the png_controlp field ' opaque ' to NULL ( or , safer , memset the whole thing . ) * / # ifdef PNG_STDIO_SUPPORTED PNG_EXPORT ( 234 , int , png_image_begin_read_from_file , ( png_imagep image , const char * file_name ) ) ; / * The named file is opened for read and the image header is filled in * from the PNG header in the file . * / PNG_EXPORT ( 235 , int , png_image_begin_read_from_stdio , ( png_imagep image , FILE * file ) ) ; / * The PNG header is read from the stdio FILE object . * / # endif / * STDIO * / PNG_EXPORT ( 236 , int , png_image_begin_read_from_memory , ( png_imagep image , png_const_voidp memory , size_t size ) ) ; / * The PNG header is read from the given memory buffer . * / PNG_EXPORT ( 237 , int , png_image_finish_read , ( png_imagep image , png_const_colorp background , void * buffer , png_int_32 row_stride , void * colormap ) ) ; / * Finish reading the image into the supplied buffer and clean up the * png_image structure . * * row_stride is the step , in byte or 2 - byte units as appropriate , * between adjacent rows . A positive stride indicates that the top - most row * is first in the buffer - the normal top - down arrangement . A negative * stride indicates that the bottom - most row is first in the buffer . * * background need only be supplied if an alpha channel must be removed from * a png_byte format and the removal is to be done by compositing on a solid * color ; otherwise it may be NULL and any composition will be done directly * onto the buffer . The value is an sRGB color to use for the background , * for grayscale output the green channel is used . * * background must be supplied when an alpha channel must be removed from a * single byte color - mapped output format , in other words if : * * 1 ) The original format from png_image_begin_read_from_ * had * PNG_FORMAT_FLAG_ALPHA set . * 2 ) The format set by the application does not . * 3 ) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and * PNG_FORMAT_FLAG_LINEAR * not * set . * * For linear output removing the alpha channel is always done by compositing * on black and background is ignored . * * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set . It must * be at least the size ( in bytes ) returned by PNG_IMAGE_COLORMAP_SIZE . * image - > colormap_entries will be updated to the actual number of entries * written to the colormap ; this may be less than the original value . * / PNG_EXPORT ( 238 , void , png_image_free , ( png_imagep image ) ) ; / * Free any data allocated by libpng in image - > opaque , setting the pointer to * NULL . May be called at any time after the structure is initialized . * / # endif / * SIMPLIFIED_READ * / # ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED / * WRITE APIS * - - - - - - - - - - * For write you must initialize a png_image structure to describe the image to * be written . To do this use memset to set the whole structure to 0 then * initialize fields describing your image . * * version : must be set to PNG_IMAGE_VERSION * opaque : must be initialized to NULL * width : image width in pixels * height : image height in rows * format : the format of the data ( image and color - map ) you wish to write * flags : set to 0 unless one of the defined flags applies ; set * PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB * values do not correspond to the colors in sRGB . * colormap_entries : set to the number of entries in the color - map ( 0 to 256 ) * / # ifdef PNG_SIMPLIFIED_WRITE_STDIO_SUPPORTED PNG_EXPORT ( 239 , int , png_image_write_to_file , ( png_imagep image , const char * file , int convert_to_8bit , const void * buffer , png_int_32 row_stride , const void * colormap ) ) ; / * Write the image to the named file . * / PNG_EXPORT ( 240 , int , png_image_write_to_stdio , ( png_imagep image , FILE * file , int convert_to_8_bit , const void * buffer , png_int_32 row_stride , const void * colormap ) ) ; / * Write the image to the given FILE object . * / # endif / * SIMPLIFIED_WRITE_STDIO * / / * With all write APIs if image is in one of the linear formats with 16 - bit * data then setting convert_to_8_bit will cause the output to be an 8 - bit PNG * gamma encoded according to the sRGB specification , otherwise a 16 - bit linear * encoded PNG file is written . * * With color - mapped data formats the colormap parameter point to a color - map * with at least image - > colormap_entries encoded in the specified format . If * the format is linear the written PNG color - map will be converted to sRGB * regardless of the convert_to_8_bit flag . * * With all APIs row_stride is handled as in the read APIs - it is the spacing * from one row to the next in component sized units ( 1 or 2 bytes ) and if * negative indicates a bottom - up row layout in the buffer . If row_stride is * zero , libpng will calculate it for you from the image width and number of * channels . * * Note that the write API does not support interlacing , sub - 8 - bit pixels or * most ancillary chunks . If you need to write text chunks ( e . g . for copyright * notices ) you need to use one of the other APIs . * / PNG_EXPORT ( 245 , int , png_image_write_to_memory , ( png_imagep image , void * memory , png_alloc_size_t * PNG_RESTRICT memory_bytes , int convert_to_8_bit , const void * buffer , png_int_32 row_stride , const void * colormap ) ) ; / * Write the image to the given memory buffer . The function both writes the * whole PNG data stream to * memory and updates * memory_bytes with the count * of bytes written . * * ' memory ' may be NULL . In this case * memory_bytes is not read however on * success the number of bytes which would have been written will still be * stored in * memory_bytes . On failure * memory_bytes will contain 0 . * * If ' memory ' is not NULL it must point to memory [ * memory_bytes ] of * writeable memory . * * If the function returns success memory [ * memory_bytes ] ( if ' memory ' is not * NULL ) contains the written PNG data . * memory_bytes will always be less * than or equal to the original value . * * If the function returns false and * memory_bytes was not changed an error * occurred during write . If * memory_bytes was changed , or is not 0 if * ' memory ' was NULL , the write would have succeeded but for the memory * buffer being too small . * memory_bytes contains the required number of * bytes and will be bigger that the original value . * / # define png_image_write_get_memory_size ( image , size , convert_to_8_bit , buffer , \ row_stride , colormap ) \ png_image_write_to_memory ( & ( image ) , 0 , & ( size ) , convert_to_8_bit , buffer , \ row_stride , colormap ) / * Return the amount of memory in ' size ' required to compress this image . * The png_image structure ' image ' must be filled in as in the above * function and must not be changed before the actual write call , the buffer * and all other parameters must also be identical to that in the final * write call . The ' size ' variable need not be initialized . * * NOTE : the macro returns true / false , if false is returned ' size ' will be * set to zero and the write failed and probably will fail if tried again . * / / * You can pre - allocate the buffer by making sure it is of sufficient size * regardless of the amount of compression achieved . The buffer size will * always be bigger than the original image and it will never be filled . The * following macros are provided to assist in allocating the buffer . * / # define PNG_IMAGE_DATA_SIZE ( image ) ( PNG_IMAGE_SIZE ( image ) + ( image ) . height ) / * The number of uncompressed bytes in the PNG byte encoding of the image ; * uncompressing the PNG IDAT data will give this number of bytes . * * NOTE : while PNG_IMAGE_SIZE cannot overflow for an image in memory this * macro can because of the extra bytes used in the PNG byte encoding . You * need to avoid this macro if your image size approaches 2 ^ 30 in width or * height . The same goes for the remainder of these macros ; they all produce * bigger numbers than the actual in - memory image size . * / # ifndef PNG_ZLIB_MAX_SIZE # define PNG_ZLIB_MAX_SIZE ( b ) ( ( b ) + ( ( ( b ) + 7 U ) > > 3 ) + ( ( ( b ) + 63 U ) > > 6 ) + 11 U ) / * An upper bound on the number of compressed bytes given ' b ' uncompressed * bytes . This is based on deflateBounds ( ) in zlib ; different * implementations of zlib compression may conceivably produce more data so * if your zlib implementation is not zlib itself redefine this macro * appropriately . * / # endif # define PNG_IMAGE_COMPRESSED_SIZE_MAX ( image ) \ PNG_ZLIB_MAX_SIZE ( ( png_alloc_size_t ) PNG_IMAGE_DATA_SIZE ( image ) ) / * An upper bound on the size of the data in the PNG IDAT chunks . * / # define PNG_IMAGE_PNG_SIZE_MAX_ ( image , image_size ) \ ( ( 8 U / * sig * / + 25 U / * IHDR * / + 16 U / * gAMA * / + 44 U / * cHRM * / + 12 U / * IEND * / + \ ( ( ( image ) . format & PNG_FORMAT_FLAG_COLORMAP ) ? / * colormap : PLTE , tRNS * / \ 12 U + 3 U * ( image ) . colormap_entries / * PLTE data * / + \ ( ( ( image ) . format & PNG_FORMAT_FLAG_ALPHA ) ? \ 12 U / * tRNS * / + ( image ) . colormap_entries : 0 U ) : 0 U ) + \ 12 U ) + ( 12 U * ( ( image_size ) / PNG_ZBUF_SIZE ) ) / * IDAT * / + ( image_size ) ) / * A helper for the following macro ; if your compiler cannot handle the * following macro use this one with the result of * PNG_IMAGE_COMPRESSED_SIZE_MAX ( image ) as the second argument ( most * compilers should handle this just fine . ) * / # define PNG_IMAGE_PNG_SIZE_MAX ( image ) \ PNG_IMAGE_PNG_SIZE_MAX_ ( image , PNG_IMAGE_COMPRESSED_SIZE_MAX ( image ) ) / * An upper bound on the total length of the PNG data stream for ' image ' . * The result is of type png_alloc_size_t , on 32 - bit systems this may * overflow even though PNG_IMAGE_DATA_SIZE does not overflow ; the write will * run out of buffer space but return a corrected size which should work . * / # endif / * SIMPLIFIED_WRITE * / / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * END OF SIMPLIFIED API * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * / # endif / * SIMPLIFIED_ { READ | WRITE } * / / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Section 6 : IMPLEMENTATION OPTIONS * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Support for arbitrary implementation - specific optimizations . The API allows * particular options to be turned on or off . ' Option ' is the number of the * option and ' onoff ' is 0 ( off ) or non - 0 ( on ) . The value returned is given * by the PNG_OPTION_ defines below . * * HARDWARE : normally hardware capabilities , such as the Intel SSE instructions , * are detected at run time , however sometimes it may be impossible * to do this in user mode , in which case it is necessary to discover * the capabilities in an OS specific way . Such capabilities are * listed here when libpng has support for them and must be turned * ON by the application if present . * * SOFTWARE : sometimes software optimizations actually result in performance * decrease on some architectures or systems , or with some sets of * PNG images . ' Software ' options allow such optimizations to be * selected at run time . * / # ifdef PNG_SET_OPTION_SUPPORTED / * HARDWARE : ARM Neon SIMD instructions supported * / # ifdef PNG_ARM_NEON_API_SUPPORTED # define PNG_ARM_NEON 0 # endif / * SOFTWARE : Force maximum window * / # define PNG_MAXIMUM_INFLATE_WINDOW 2 / * SOFTWARE : Check ICC profile for sRGB * / # define PNG_SKIP_sRGB_CHECK_PROFILE 4 / * HARDWARE : MIPS MSA SIMD instructions supported * / # ifdef PNG_MIPS_MSA_API_SUPPORTED # define PNG_MIPS_MSA 6 # endif / * SOFTWARE : Disable Adler32 check on IDAT * / # ifdef PNG_DISABLE_ADLER32_CHECK_SUPPORTED # define PNG_IGNORE_ADLER32 8 # endif / * HARDWARE : PowerPC VSX SIMD instructions supported * / # ifdef PNG_POWERPC_VSX_API_SUPPORTED # define PNG_POWERPC_VSX 10 # endif / * HARDWARE : MIPS MMI SIMD instructions supported * / # ifdef PNG_MIPS_MMI_API_SUPPORTED # define PNG_MIPS_MMI 12 # endif / * HARDWARE : RISC - V RVV SIMD instructions supported * / # ifdef PNG_RISCV_RVV_API_SUPPORTED # define PNG_RISCV_RVV 14 # endif / * Next option - numbers must be even * / # define PNG_OPTION_NEXT 16 / * Return values : NOTE : there are four values and ' off ' is * not * zero * / # define PNG_OPTION_UNSET 0 / * Unset - defaults to off * / # define PNG_OPTION_INVALID 1 / * Option number out of range * / # define PNG_OPTION_OFF 2 # define PNG_OPTION_ON 3 PNG_EXPORT ( 244 , int , png_set_option , ( png_structrp png_ptr , int option , int onoff ) ) ; # endif / * SET_OPTION * / / * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * END OF HARDWARE AND SOFTWARE OPTIONS * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * / # ifdef PNG_APNG_SUPPORTED PNG_EXPORT ( 260 , png_uint_32 , png_get_acTL , ( png_structp png_ptr , png_infop info_ptr , png_uint_32 * num_frames , png_uint_32 * num_plays ) ) ; PNG_EXPORT ( 261 , png_uint_32 , png_set_acTL , ( png_structp png_ptr , png_infop info_ptr , png_uint_32 num_frames , png_uint_32 num_plays ) ) ; PNG_EXPORT ( 262 , png_uint_32 , png_get_num_frames , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 263 , png_uint_32 , png_get_num_plays , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 264 , png_uint_32 , png_get_next_frame_fcTL , ( png_structp png_ptr , png_infop info_ptr , png_uint_32 * width , png_uint_32 * height , png_uint_32 * x_offset , png_uint_32 * y_offset , png_uint_16 * delay_num , png_uint_16 * delay_den , png_byte * dispose_op , png_byte * blend_op ) ) ; PNG_EXPORT ( 265 , png_uint_32 , png_set_next_frame_fcTL , ( png_structp png_ptr , png_infop info_ptr , png_uint_32 width , png_uint_32 height , png_uint_32 x_offset , png_uint_32 y_offset , png_uint_16 delay_num , png_uint_16 delay_den , png_byte dispose_op , png_byte blend_op ) ) ; PNG_EXPORT ( 266 , png_uint_32 , png_get_next_frame_width , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 267 , png_uint_32 , png_get_next_frame_height , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 268 , png_uint_32 , png_get_next_frame_x_offset , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 269 , png_uint_32 , png_get_next_frame_y_offset , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 270 , png_uint_16 , png_get_next_frame_delay_num , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 271 , png_uint_16 , png_get_next_frame_delay_den , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 272 , png_byte , png_get_next_frame_dispose_op , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 273 , png_byte , png_get_next_frame_blend_op , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 274 , png_byte , png_get_first_frame_is_hidden , ( png_structp png_ptr , png_infop info_ptr ) ) ; PNG_EXPORT ( 275 , png_uint_32 , png_set_first_frame_is_hidden , ( png_structp png_ptr , png_infop info_ptr , png_byte is_hidden ) ) ; # ifdef PNG_READ_APNG_SUPPORTED PNG_EXPORT ( 276 , void , png_read_frame_head , ( png_structp png_ptr , png_infop info_ptr ) ) ; # ifdef PNG_PROGRESSIVE_READ_SUPPORTED PNG_EXPORT ( 277 , void , png_set_progressive_frame_fn , ( png_structp png_ptr , png_progressive_frame_ptr frame_info_fn , png_progressive_frame_ptr frame_end_fn ) ) ; # endif / * PROGRESSIVE_READ * / # endif / * READ_APNG * / # ifdef PNG_WRITE_APNG_SUPPORTED PNG_EXPORT ( 278 , void , png_write_frame_head , ( png_structp png_ptr , png_infop info_ptr , png_bytepp row_pointers , png_uint_32 width , png_uint_32 height , png_uint_32 x_offset , png_uint_32 y_offset , png_uint_16 delay_num , png_uint_16 delay_den , png_byte dispose_op , png_byte blend_op ) ) ; PNG_EXPORT ( 279 , void , png_write_frame_tail , ( png_structp png_ptr , png_infop info_ptr ) ) ; # endif / * WRITE_APNG * / # endif / * APNG * / / * Maintainer : Put new public prototypes here ^ , in libpng . 3 , in project * defs , and in scripts / symbols . def . * / / * The last ordinal number ( this is the * last * one already used ; the next * one to use is one more than this . ) * / # ifdef PNG_EXPORT_LAST_ORDINAL # ifdef PNG_APNG_SUPPORTED PNG_EXPORT_LAST_ORDINAL ( 279 ) ; # else PNG_EXPORT_LAST_ORDINAL ( 259 ) ; # endif / * APNG * / # endif # ifdef _ _ cplusplus } # endif # endif / * PNG_VERSION_INFO_ONLY * / / * Do not put anything past this line * / # endif / * PNG_H * /
Messung V0.5 in Prozent C=95 H=100 G=97
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