/* png.h - header file for PNG reference library
*
* libpng version 1.6.45
*
* Copyright (c) 2018-2025 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 1.6.45, January 2025:
* Cosmin Truta
* See also "Contributing Authors", below.
*/
/*
* COPYRIGHT NOTICE, DISCLAIMER, and LICENSE
* =========================================
*
* PNG Reference Library License version 2
* ---------------------------------------
*
* * Copyright (c) 1995-2025 The PNG Reference Library Authors.
* * Copyright (c) 2018-2025 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 (88x31) and "pngnow.png" (98x31).
*/
/*
* 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 0.89c, which was
* the first widely used release:
*
* source png.h png.h shared-lib
* version string int version
* ------- ------ ----- ----------
* 0.89c "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]
* 0.97b "1.00.97 beta 7" 1.00.97 97 1.0.1 [should have been 2.0.97]
* 0.97c 0.97 97 2.0.97
* 0.98 0.98 98 2.0.98
* 0.99 0.99 98 2.0.99
* 0.99a-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
* 1.0.1a-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
* 1.0.2a-b 10003 version, except as noted.
* 1.0.3 10003
* 1.0.3a-d 10004
* 1.0.4 10004
* 1.0.4a-f 10005
* 1.0.5 (+ 2 patches) 10005
* 1.0.5a-d 10006
* 1.0.5e-r 10100 (not source compatible)
* 1.0.5s-v 10006 (not binary compatible)
* 1.0.6 (+ 3 patches) 10006 (still binary incompatible)
* 1.0.6d-f 10007 (still binary incompatible)
* 1.0.6g 10007
* 1.0.6h 10007 10.6h (testing xy.z so-numbering)
* 1.0.6i 10007 10.6i
* 1.0.6j 10007 2.1.0.6j (incompatible with 1.0.0)
* 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 (binary compatible)
* 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 (binary compatible)
* 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 (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]
* ...
* 1.6.45 16 10645 16.so.16.45[.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 1.0.6j; 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
"1.6.45"
#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 45
/* 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
PNG_LIBPNG_BUILD_STABLE only */
#define PNG_LIBPNG_BUILD_PRIVATE 16
/* Cannot be OR'ed with
PNG_LIBPNG_BUILD_SPECIAL */
#define PNG_LIBPNG_BUILD_SPECIAL 32
/* Cannot be OR'ed with
PNG_LIBPNG_BUILD_PRIVATE */
#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 10645
/* 1.6.45 */
/* 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 \
(PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
#else
# ifdef PNG_LIBPNG_SPECIALBUILD
# define PNG_LIBPNG_BUILD_TYPE \
(PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
# 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 __cplusplus
extern "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 0x00
#define PNG_DISPOSE_OP_BACKGROUND 0x01
#define PNG_DISPOSE_OP_PREVIOUS 0x02
/* blend_op flags from inside fcTL */
#define PNG_BLEND_OP_SOURCE 0x00
#define PNG_BLEND_OP_OVER 0x01
#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_45;
/* 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_struct
{
png_byte red;
png_byte green;
png_byte blue;
} png_color;
typedef png_color * png_colorp;
typedef const png_color * png_const_colorp;
typedef png_color * * png_colorpp;
typedef struct png_color_16_struct
{
png_byte index;
/* used for palette files */
png_uint_16 red;
/* for use in red green blue files */
png_uint_16 green;
png_uint_16 blue;
png_uint_16 gray;
/* for use in grayscale files */
} png_color_16;
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
{
png_byte red;
/* for use in red green blue files */
png_byte green;
png_byte blue;
png_byte gray;
/* for use in grayscale files */
png_byte alpha;
/* for alpha channel files */
} png_color_8;
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_struct
{
png_uint_16 red;
png_uint_16 green;
png_uint_16 blue;
png_uint_16 alpha;
png_uint_16 frequency;
} png_sPLT_entry;
typedef 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
{
png_charp name;
/* palette name */
png_byte depth;
/* depth of palette samples */
png_sPLT_entryp entries;
/* palette entries */
png_int_32 nentries;
/* number of palette entries */
} png_sPLT_t;
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_struct
{
int compression;
/* compression value:
-1: tEXt, none
0: zTXt, deflate
1: iTXt, none
2: iTXt, deflate */
png_charp key;
/* keyword, 1-79 character description of "text" */
png_charp text;
/* comment, may be an empty string (ie "")
or a NULL pointer */
size_t text_length;
/* length of the text string */
size_t itxt_length;
/* length of the itxt string */
png_charp lang;
/* language code, 0-79 characters
or a NULL pointer */
png_charp lang_key;
/* keyword translated UTF-8 string, 0 or more
chars or a NULL pointer */
} png_text;
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).
* The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
#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
{
png_uint_16 year;
/* full year, as in, 1995 */
png_byte month;
/* month of year, 1 - 12 */
png_byte day;
/* day of month, 1 - 31 */
png_byte hour;
/* hour of day, 0 - 23 */
png_byte minute;
/* minute of hour, 0 - 59 */
png_byte second;
/* second of minute, 0 - 60 (for leap seconds) */
} png_time;
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_t
{
png_byte name[5];
/* Textual chunk name with '\0' terminator */
png_byte *data;
/* Data, should not be modified on read! */
size_t size;
/* 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.
*/
png_byte location;
/* mode of operation at read time */
}
png_unknown_chunk;
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 0x01
#define PNG_HAVE_PLTE 0x02
#define PNG_AFTER_IDAT 0x08
/* Maximum positive integer used in PNG is (2^31)-1 */
#define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
#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)0x7fffffffL)
#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 0x0001U
#define PNG_INFO_sBIT 0x0002U
#define PNG_INFO_cHRM 0x0004U
#define PNG_INFO_PLTE 0x0008U
#define PNG_INFO_tRNS 0x0010U
#define PNG_INFO_bKGD 0x0020U
#define PNG_INFO_hIST 0x0040U
#define PNG_INFO_pHYs 0x0080U
#define PNG_INFO_oFFs 0x0100U
#define PNG_INFO_tIME 0x0200U
#define PNG_INFO_pCAL 0x0400U
#define PNG_INFO_sRGB 0x0800U
/* GR-P, 0.96a */
#define PNG_INFO_iCCP 0x1000U
/* ESR, 1.0.6 */
#define PNG_INFO_sPLT 0x2000U
/* ESR, 1.0.6 */
#define PNG_INFO_sCAL 0x4000U
/* ESR, 1.0.6 */
#define PNG_INFO_IDAT 0x8000U
/* ESR, 1.0.6 */
#define PNG_INFO_eXIf 0x10000U
/* GR-P, 1.6.31 */
#define PNG_INFO_cICP 0x20000U
#ifdef PNG_APNG_SUPPORTED
#define PNG_INFO_acTL 0x40000U
#define PNG_INFO_fcTL 0x80000U
#endif
/* 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
{
png_uint_32 width;
/* width of row */
size_t rowbytes;
/* number of bytes in row */
png_byte color_type;
/* color type of row */
png_byte bit_depth;
/* bit depth of row */
png_byte channels;
/* number of channels (1, 2, 3, or 4) */
png_byte pixel_depth;
/* bits per pixel (depth * channels) */
} png_row_info;
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, (png_structp, png_const_charp));
typedef PNG_CALLBACK(
void, *png_rw_ptr, (png_structp, png_bytep, size_t));
typedef PNG_CALLBACK(
void, *png_flush_ptr, (png_structp));
typedef PNG_CALLBACK(
void, *png_read_status_ptr, (png_structp, png_uint_32,
int));
typedef PNG_CALLBACK(
void, *png_write_status_ptr, (png_structp, png_uint_32,
int));
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
typedef PNG_CALLBACK(
void, *png_progressive_info_ptr, (png_structp, png_infop));
typedef PNG_CALLBACK(
void, *png_progressive_end_ptr, (png_structp, png_infop));
#ifdef PNG_APNG_SUPPORTED
typedef PNG_CALLBACK(
void, *png_progressive_frame_ptr, (png_structp,
png_uint_32));
#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, (png_structp, png_bytep,
png_uint_32,
int));
#endif
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
typedef PNG_CALLBACK(
void, *png_user_transform_ptr, (png_structp, png_row_infop,
png_bytep));
#endif
#ifdef PNG_USER_CHUNKS_SUPPORTED
typedef PNG_CALLBACK(
int, *png_user_chunk_ptr, (png_structp,
png_unknown_chunkp));
#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!
*/
PNG_FUNCTION(
void, (PNGCAPI *png_longjmp_ptr), (jmp_buf,
int),
typedef);
#endif
/* Transform masks for the high-level interface */
#define PNG_TRANSFORM_IDENTITY 0x0000
/* read and write */
#define PNG_TRANSFORM_STRIP_16 0x0001
/* read only */
#define PNG_TRANSFORM_STRIP_ALPHA 0x0002
/* read only */
#define PNG_TRANSFORM_PACKING 0x0004
/* read and write */
#define PNG_TRANSFORM_PACKSWAP 0x0008
/* read and write */
#define PNG_TRANSFORM_EXPAND 0x0010
/* read only */
#define PNG_TRANSFORM_INVERT_MONO 0x0020
/* read and write */
#define PNG_TRANSFORM_SHIFT 0x0040
/* read and write */
#define PNG_TRANSFORM_BGR 0x0080
/* read and write */
#define PNG_TRANSFORM_SWAP_ALPHA 0x0100
/* read and write */
#define PNG_TRANSFORM_SWAP_ENDIAN 0x0200
/* read and write */
#define PNG_TRANSFORM_INVERT_ALPHA 0x0400
/* read and write */
#define PNG_TRANSFORM_STRIP_FILLER 0x0800
/* write only */
/* Added to libpng-1.2.34 */
#define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
#define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000
/* write only */
/* Added to libpng-1.4.0 */
#define PNG_TRANSFORM_GRAY_TO_RGB 0x2000
/* read only */
/* Added to libpng-1.5.4 */
#define PNG_TRANSFORM_EXPAND_16 0x4000
/* read only */
#if ~0U > 0xffffU
/* or else this might break on a 16-bit machine */
#define PNG_TRANSFORM_SCALE_16 0x8000
/* read only */
#endif
/* Flags for MNG supported features */
#define PNG_FLAG_MNG_EMPTY_PLTE 0x01
#define PNG_FLAG_MNG_FILTER_64 0x04
#define PNG_ALL_MNG_FEATURES 0x05
/* 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, (png_structp,
png_alloc_size_t));
typedef PNG_CALLBACK(
void, *png_free_ptr, (png_structp, png_voidp));
/* 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 */
PNG_EXPORT(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.
*/
PNG_EXPORT(2,
void, png_set_sig_bytes, (png_structrp png_ptr,
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).
*/
PNG_EXPORT(3,
int, png_sig_cmp, (png_const_bytep sig, size_t start,
size_t num_to_check));
/* 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 0x00
#define PNG_FILTER_NONE 0x08
#define PNG_FILTER_SUB 0x10
#define PNG_FILTER_UP 0x20
#define PNG_FILTER_AVG 0x40
#define PNG_FILTER_PAETH 0x80
#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 */
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