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/* png.h - header file for PNG reference library
* libpng version 1.7.0beta90, August 19, 2017
* Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 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 1.7.0beta90, August 19, 2017:
* Glenn Randers-Pehrson.
* See also "Contributing Authors", below.
* If you modify libpng you may insert additional notices immediately following
* this sentence.
* This code is released under the libpng license.
* libpng versions 1.0.7, July 1, 2000 through 1.7.0beta90, August 19, 2017 are
* Copyright (c) 2000-2002, 2004, 2006-2017 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
* 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.
* The name "libpng" has not been registered by the Copyright owner
* as a trademark in any jurisdiction. However, because libpng has
* been distributed and maintained world-wide, continually since 1995,
* the Copyright owner claims "common-law trademark protection" in any
* jurisdiction where common-law trademark is recognized.
* Libpng is OSI Certified Open Source Software. OSI Certified Open Source is
* a certification mark of the Open Source Initiative. OSI has not addressed
* the additional disclaimers inserted at version 1.0.7.
* The Copyright owner believes that the Export Control Classification
* Number (ECCN) for libpng is EAR99, which means not subject to export
* controls or International Traffic in Arms Regulations (ITAR) because
* it is open source, publicly available software, that does not contain
* any encryption software. See the EAR, paragraphs 734.3(b)(3) and
* 734.7(b).
* 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 (incompatible with 1.0.0)
* 1.0.7beta11-14 DLLNUM 10007 (binary compatible)
* 1.0.7beta15-18 1 10007 (binary compatible)
* 1.0.7rc1-2 1 10007 (binary compatible)
* 1.0.7 1 10007 (still compatible)
* ...
* 1.0.19 10 10019[.0]
* ...
* 1.2.56 13 10253[.0]
* ...
* 1.5.27 15 10523[.0]
* ...
* 1.6.22 16 10622[.0]
* ...
* 1.7.0alpha01-10 17 10700[.0]
* 1.7.0beta01-84 17 10700[.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.
* DLLNUM will change each time there are forward or backward changes
* in binary compatibility (e.g., when a new feature is added).
* See libpng.txt or libpng.3 for more information. The PNG specification
* is available as a W3C Recommendation and as an ISO Specification,
* <
* Y2K compliance in libpng:
* =========================
* August 19, 2017
* Since the PNG Development group is an ad-hoc body, we can't make
* an official declaration.
* This is your unofficial assurance that libpng from version 0.71 and
* upward through 1.7.0beta90 are Y2K compliant. It is my belief that
* earlier versions were also Y2K compliant.
* Libpng only has two year fields. One is a 2-byte unsigned integer
* that will hold years up to 65535. The other, which is deprecated,
* holds the date in text format, and will hold years up to 9999.
* The integer is
* "png_uint_16 year" in png_time_struct.
* The string is
* "char time_buffer[29]" in png_struct. This is no longer used
* in libpng-1.6.x and will be removed from libpng-1.7.0.
* There are seven time-related functions:
* png.c: png_convert_to_rfc_1123_buffer() in png.c
* (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
* png_convert_to_rfc_1152() in error prior to libpng-0.98)
* png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
* png_convert_from_time_t() in pngwrite.c
* png_get_tIME() in pngget.c
* png_handle_tIME() in pngrutil.c, called in pngread.c
* png_set_tIME() in pngset.c
* png_write_tIME() in pngwutil.c, called in pngwrite.c
* All handle dates properly in a Y2K environment. The
* png_convert_from_time_t() function calls gmtime() to convert from system
* clock time, which returns (year - 1900), which we properly convert to
* the full 4-digit year. There is a possibility that libpng applications
* are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
* function, or that they are incorrectly passing only a 2-digit year
* instead of "year - 1900" into the png_convert_from_struct_tm() function,
* but this is not under our control. The libpng documentation has always
* stated that it works with 4-digit years, and the APIs have been
* documented as such.
* The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
* integer to hold the year, and can hold years as large as 65535.
* zlib, upon which libpng depends, is also Y2K compliant. It contains
* no date-related code.
* Glenn Randers-Pehrson
* libpng maintainer
* PNG Development Group
#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
* <>
* 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 "1.7.0beta90"
#define PNG_HEADER_VERSION_STRING " libpng version 1.7.0beta90 - August 19, 2017\n"
/* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
/* This should match the numeric part of the final component of
* PNG_LIBPNG_VER_STRING, omitting any leading zero:
/* Release Status */
/* 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
/* 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's xxyyzz, where x=major, y=minor, z=release
#define PNG_LIBPNG_VER 10700 /* 1.7.0 */
/* 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"
/* Machine specific configuration. */
# include "pngconf.h"
* 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 */
# else
# endif
/* 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. ISO-PNG constants and definitions; values defined by PNG and not specific
* to the libpng API.
* 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: ISO PNG constants and macros. */
/* ISO-PNG defines byte encodings for 16 and 32-bit unsigned values and 32-bit
* signed values. The macros PNG_U16, PNG_U32 and PNG_S32 return values of type
* (png_uint_16), (png_uint_32) and (png_int_32) which are target machine
* specific representations of these values, using the types defined in
* pngconf.h. The macros take two or four byte values in the order in which
* they would occur in a PNG stream.
* These macros must return compile time constants if passed constant values -
* machine specific implementations are not permitted. These macros are used by
* default in the API functions/macros png_get_uint_16, png_get_uint_32,
* png_get_uint_31 and png_get_int_32 declared below: these functions or macros
* are the correct places for machine specific implementations (such as hardware
* specific instructions.)
* The macros defined here are generic and intended to give maximum flexibility
* in implementation to the compiler; only PNG_S32 contains a sequence point,
* there are no side effects and the expressions used permit the maximum
* parallelization (relevant because the four bytes may be loaded in parallel.)
#define PNG_u2(b1, b2) (((unsigned int)(b1) << 8) + (b2))
#define PNG_U16(b1, b2) ((png_uint_16)/*SAFE*/PNG_u2(b1, b2))
#define PNG_U32(b1, b2, b3, b4)\
(((png_uint_32)/*SAFE*/PNG_u2(b1, b2) << 16) + PNG_u2(b3, b4))
/* ISO-PNG states that signed 32-bit values are stored in two's complement
* format. There is no guarantee that (png_int_32) is exactly 32 bits, so the
* following macro tests for a negative number and generates the machine format
* directly by portable arithmetic operations. The cost is that the argument
* 'b1' is evaluated twice.
* NOTE: the 0x7fffffffU BIC is there to ensure that potential overflow in the
* cast does not occur. This fixes the case where 1's complement machines could
* be forced into an overflow by an invalid value in the stream and, therefore,
* potentially raise an arithmetic exception; the invalid value is converted to
* 0 and any resultant problems will be caught later in the libpng checking.
#define PNG_S32(b1, b2, b3, b4) ((b1) & 0x80\
? -(png_int_32)(((PNG_U32(b1, b2, b3, b4)^0xffffffffU)+1U)&0x7fffffffU)\
: (png_int_32)PNG_U32(b1, b2, b3, b4))
/* Constants for known chunk types.
* MAINTAINERS: If you need to add a chunk, define the name here.
* For historical reasons these constants have the form png_<name>; i.e.
* the prefix is lower case. Please use decimal values as the parameters to
* match the ISO PNG specification and to avoid relying on the C locale
* interpretation of character values. Please keep the list sorted.
* Notice that PNG_U32 is used to define a 32-bit value for the 4 byte chunk
* type. In fact the specification does not express chunk types this way,
* however using a 32-bit value means that the chunk type can be read from the
* stream using exactly the same code as used for a 32-bit unsigned value and
* can be examined far more efficiently (using one arithmetic compare).
* Prior to 1.5.6 the chunk type constants were expressed as C strings. The
* libpng API still uses strings for 'unknown' chunks and a macro,
* PNG_STRING_FROM_CHUNK, allows a string to be generated if required. Notice
* that for portable code numeric values must still be used; the string "IHDR"
* is not portable and neither is PNG_U32('I', 'H', 'D', 'R').
* In 1.7.0 the definitions were made public in png.h to avoid having to
* duplicate the same definitions in application code.
* "Register of PNG Public Chunks and Keywords, version 1.4.6"
* "Extensions to the PNG Specification, version 1.4.0"
#define png_IDAT PNG_U32( 73, 68, 65, 84)
#define png_IEND PNG_U32( 73, 69, 78, 68)
#define png_IHDR PNG_U32( 73, 72, 68, 82)
#define png_PLTE PNG_U32( 80, 76, 84, 69)
#define png_bKGD PNG_U32( 98, 75, 71, 68)
#define png_cHRM PNG_U32( 99, 72, 82, 77)
#define png_dSIG PNG_U32(100, 83, 73, 71) /* separate spec */
#define png_fRAc PNG_U32(102, 82, 65, 99) /* registered, not defined */
#define png_gAMA PNG_U32(103, 65, 77, 65)
#define png_gIFg PNG_U32(103, 73, 70, 103)
#define png_gIFt PNG_U32(103, 73, 70, 116) /* deprecated */
#define png_gIFx PNG_U32(103, 73, 70, 120)
#define png_hIST PNG_U32(104, 73, 83, 84)
#define png_iCCP PNG_U32(105, 67, 67, 80)
#define png_iTXt PNG_U32(105, 84, 88, 116)
#define png_oFFs PNG_U32(111, 70, 70, 115)
#define png_pCAL PNG_U32(112, 67, 65, 76)
#define png_pHYs PNG_U32(112, 72, 89, 115)
#define png_sBIT PNG_U32(115, 66, 73, 84)
#define png_sCAL PNG_U32(115, 67, 65, 76)
#define png_sPLT PNG_U32(115, 80, 76, 84)
#define png_sRGB PNG_U32(115, 82, 71, 66)
#define png_sTER PNG_U32(115, 84, 69, 82)
#define png_tEXt PNG_U32(116, 69, 88, 116)
#define png_tIME PNG_U32(116, 73, 77, 69)
#define png_tRNS PNG_U32(116, 82, 78, 83)
#define png_zTXt PNG_U32(122, 84, 88, 116)
/* The following will work on (signed char*) strings, whereas the PNG_U32 macro
* used directory would fail on top-bit-set values because of the sign
* extension.
PNG_U32(0xff&(s)[0], 0xff&(s)[1], 0xff&(s)[2], 0xff&(s)[3])
/* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
* signed and the argument is a (char[]) This macro will fail miserably on
* systems where (char) is more than 8 bits.
(void)(((char*)(s))[0]=(char)(((c)>>24) & 0xff), \
((char*)(s))[1]=(char)(((c)>>16) & 0xff),\
((char*)(s))[2]=(char)(((c)>>8) & 0xff), \
((char*)(s))[3]=(char)((c & 0xff)))
/* Do the same but terminate with a null character. */
(void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
/* Test on flag values as defined in the spec (section 5.4): */
#define PNG_CHUNK_ANCILLARY(c) (1 & ((c) >> 29))
#define PNG_CHUNK_PRIVATE(c) (1 & ((c) >> 21))
#define PNG_CHUNK_RESERVED(c) (1 & ((c) >> 13))
#define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >> 5))
/* 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?
* 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.
/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* Section 3: type definitions, including structures and compile time
* constants.
* See pngconf.h for base types that vary by machine/system
/* 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_7_0beta90;
/* 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;
/* 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.
* The location field (added in libpng 1.7.0) records where the text chunk was
* found when png_get_text is used. When png_set_text is used the field in the
* structure passed in is ignored and, instead, the field is set to the current
* write position.
* Prior to 1.7.0 the write behavior was the same; the text fields were written
* (once) at the next write_info call, however the read mechanism did not record
* the chunk location so if an info_struct from read was passed to the write
* APIs the text chunks would all be written at the start (before PLTE).
typedef struct png_text_struct
int compression; /* compression value:
-1: tEXt, none
0: zTXt, deflate
1: iTXt, none
2: iTXt, deflate */
png_byte location; /* 1: PNG_HAVE_IHDR
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;
/* Supported compression types for text in PNG files (tEXt, and zTXt).
* The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
/* These values were used to prevent double write of text chunks in versions
* prior to 1.7.0. They are never set now; if you need them #define the
* _SUPPORTED macro.
#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;
/* 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 *data; /* Data, should not be modified on read! */
png_uint_32 size; /* Size of data, must not exceed 0x7fffffff.
* API CHANGE 1.7.0: changed from 'size_t'
png_byte name[5]; /* Textual chunk name with '\0' terminator */
/* 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 */
typedef png_unknown_chunk * png_unknown_chunkp;
typedef const png_unknown_chunk * png_const_unknown_chunkp;
typedef png_unknown_chunk * * png_unknown_chunkpp;
/* Flag values for the chunk location byte. */
#define PNG_HAVE_IHDR 0x01U
#define PNG_HAVE_PLTE 0x02U
#define PNG_AFTER_IDAT 0x08U
/* 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 */
/* color types. Note that not all combinations are legal */
/* aliases */
/* 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 */
/* This is for filter method. PNG 1.0-1.2 only defines a single method.
* NOTE: CONFUSING NAME. The specification refers to a 'method', one of the
* defines below, and a 'type', one of the FILTER_VALUE defines.
* Historically libpng uses TYPE for 'method' and VALUE for 'type'.
#define PNG_FILTER_TYPE_BASE 0 /* Single row per-byte filtering */
#define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
/* Filter values defined for method '0' (PNG_FILTER_TYPE_BASE) in the PNG
* specification.
#define PNG_FILTER_VALUE_LAST 5 /* Not a valid value */
/* 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_LAST 4 /* Not a valid value */
/* This is for text chunks */
/* Maximum number of entries in PLTE/sPLT/tRNS arrays */
/* 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 */
/* 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,
typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
/* WARNING: the API for this callback is poorly documented and produces
* unexpected results when dealing with interlaced images. For non-interlaced
* images the parameters are straightforward:
* next_row: a pointer to the transformed row read from the PNG input
* stream, it has png_get_image_width() pixels.
* row_y: the y ordinate of the image; 0..png_get_image_height()-1
* pass: 0
* For interlaced images if png_set_interlace_handling has been called (libpng
* does *not* call this itself) the parameters are the same except that the
* pass will be the pass in the range 0..6 (NOTE: one less than the PNG spec)
* and 'next_row' will be NULL if (and only if) the row does not contribute
* to the output in 'blocky' display mode.
* pass: 0..6
* If 'next_row' is not NULL it is necessary for the application to combine the
* pixels with the output. This can most easily be done by calling
* png_progressive_combine_row(). Note that the 'next_row' data cannot be
* changed; even though the value is passed to png_progressive_combine_row the
* pointer is not used, it is just a flag , if it is NULL nothing will happen.
* If png_set_interlace_handling has not been called the callback only gets
* called for original PNG interlaced row:
* row_y: the y ordinate in the pass; 0..PNG_PASS_ROWS()-1
* What is more if PNG_PASS_COLS() is 0 the entire pass will be skipped. The
* row data is not full width and there is no guarantee that the buffer passed
* in 'next_row' is able to accomodate the full width of output pixels, however
* 'next_row' will never be NULL.
* Use PNG_ROW_FROM_PASS_ROW(row_y, pass) and PNG_COL_FROM_PASS_COL(col, pass)
* to find the output pixel (x,y) given an interlaced sub-image pixel
* (row_y,col,pass). (See below for these macros.)
* Note that in this latter case if you want to do the 'blocky' display update
* method you have to work out all the details yourself with regard to which
* pixels to set for each row and whether to replicate it to the following
* rows of the image.
typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp,
png_bytep next_row, png_uint_32 row_y, int pass));
typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
/* not used anywhere */
/* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
/* 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), PNGARG((jmp_buf, int)), typedef);
/* 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_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 */
#define PNG_TRANSFORM_SCALE_16 0x8000 /* read only */
/* Flags for MNG supported features */
#define PNG_FLAG_MNG_FILTER_64 0x04
/* 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,
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 (ie 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).
#define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
/* 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),
/* 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),
/* These APIs control the size of the buffer used for reading IDAT chunks in the
* sequential read code and the size of the IDAT chunks produced when writing.
* They have no effect on the progressive read code. In both read and write
* cases it will be necessary to allocate at least this amount of buffer space.
* The default value is PNG_IDAT_READ_SIZE on read and PNG_ZBUF_SIZE on write.
* The valid range is 1..0x7FFFFFFF on write and 1..max(uInt) on read, where
* uInt is the type declared by zlib.h. On write setting the largest value will
* typically cause the PNG image data to be written in one chunk; this gives the
* smallest PNG and has little or no effect on applications that read the PNG.
* DEPRECATED: use png_set_IDAT_size on write and png_set_read_buffer_size on
* read.
PNG_EXPORTA(6, png_alloc_size_t, png_get_compression_buffer_size,
(png_const_structrp png_ptr), PNG_DEPRECATED);
PNG_EXPORTA(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
png_alloc_size_t size), PNG_DEPRECATED);
#define png_set_read_buffer_size(p,size) (png_setting((p),\
PNG_SR_COMPRESS_buffer_size, (size), 0))
/* The size of the buffer used while processing compressed data, both single
* chunk data (zTXt, iTXt, iCCP) and IDAT data. With IDAT data in libpng 1.7
* IDATs are read until the end or until the buffer is full; this means that
* you can optimize the buffer size for the particular memory behavior of
* your system and, possibly, your application.
* NOTE: the result (on success) is 0, which is actually an invalid value.
* Retrieving the current value is not possible.
/* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
* match up.
/* 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))))
# define png_jmpbuf(png_ptr) \
/* 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),
/* Reset the compression stream -- Removed from libpng-1.7.0 */
PNG_REMOVED(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED)
/* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
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_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),
/* 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_voidp 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_voidp 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),
/* Removed from libpng-1.7.0 */
PNG_REMOVED(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));
/* Read the information before the actual image data. */
PNG_EXPORT(22, void, png_read_info,
(png_structrp png_ptr, png_inforp info_ptr));
/* 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 has been removed (in libpng 1.7.0).
PNG_REMOVED(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
png_const_timep ptime),PNG_DEPRECATED)
PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
png_const_timep ptime));
/* Convert from a struct tm to png_time */
PNG_EXPORT(24, PNG_DEPRECATED 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, PNG_DEPRECATED void, png_convert_from_time_t, (png_timep ptime,
time_t ttime));
#endif /* CONVERT_tIME */
/* 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));
/* 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));
/* Use blue, green, red order for pixels. */
PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
/* Expand the grayscale to 24-bit RGB if necessary. */
PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
/* Reduce RGB to grayscale. */
#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))
/* Convert RGB pixels to gray (CIE Y) values, the red and green value must be
* less than or equal to 1, if either is negative a set of defaults
* corresponding to the sRGB standard are used.
* The error action specifies whether to check for r==g==b in each pixel, if
* it is 0 (PNG_ERROR_ACTION_NO_CHECK; added in libpng 1.7.0) no check will
* be performed, otherwise a check is performed and the result can be
* retrieved using png_get_rgb_to_gray_status (which just returns a
* true if a non-gray pixel was encountered).
* Pass PNG_ERROR_ACTION_ERROR if you are confident that the image only
* contains gray pixels (you have already checked); the check is still
* performed but a very optimized code path is used for RGB to gray
* convertion.
* If you want to extract a single channel pass PNG_FP_1 for the coefficient
* for that channel and 0 for the rest (0 for both red and green to extract
* blue).
* NOTE: the default coefficients used if negative values are passed for red
* or green are based on the cHRM chunk if available, otherwise sRGB. The
* calculation returns the Y (luminance value) corresponding to the white
* VALUE. It is the luminance of the pixel perceived by a viewer completely
* adapted to the white point of the PNG, this may not be what you want
* because to interpret it you have to also record the white point of the
* PNG. To obtain CIEXYZ Y values read the cHRM chunk XYZ values and
* chromatically adapt them to D50
PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
png_colorp palette));
/* 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 reencode
* 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))
/* 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 */
/* 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 preceeded 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 ouput 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.
PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
/* Add a filler byte to 8-bit Gray or 24-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 */
/* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
png_uint_32 filler, int flags));
/* Swap bytes in 16-bit depth files. */
PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
/* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
/* Swap packing order of pixels in bytes. */
PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
/* Converts files to legal bit depths. */
PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
/* 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));
/* Invert monochrome files */
PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
/* 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))
/* Scale a 16-bit depth file down to 8-bit, accurately. */
PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
#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));
/* 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));
/* The threshold on gamma processing is configurable but hard-wired into the
* library. The following is the floating point variant.
/* 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))
PNG_REMOVED(51, void, png_set_flush, (png_structrp png_ptr, int nrows),
#define png_set_flush(p,v) (png_setting((p), PNG_SW_FLUSH, 0, (v)))
/* Set how many lines between output flushes - 0 for no flushing. The result
* on success is always 0.
/* Flush the current PNG output buffer */
PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
#endif /* WRITE_FLUSH */
/* 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));
/* 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));
/* Read a row of data. */
PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
png_bytep display_row));
/* Read the whole image into memory at once. */
PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
/* 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));
/* Read the end of the PNG file. */
PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
/* 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 on read */
PNG_REMOVED(66, void, png_set_crc_action, (png_structrp png_ptr,
int crit_action, int ancil_action), PNG_EMPTY)
#define png_set_crc_action(png_ptr, crit, ancil)\
(png_setting((png_ptr), PNG_SR_CRC_ACTION, (crit), (ancil)))
/* 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 */
/* Write image filtering and compression options.
* These settings just change the very low level encoding of a PNG. The changes
* make no difference to the image or the meta-data stored in the PNG. The API
* used to make these changes can be disabled in a very minimal configuration,
* if it is your compiler will report undefined values when the APIs below are
* used.
* Write settings defined here, in order of ease of use:
* 1) Write compression settings: whether to optimize the write and the PNG
* that results for read speed, final PNG size, write speed or memory
* usage.
* 2) IDAT size: What size to make the IDAT chunks in the PNG.
* 3) PNG row filters to consider when writing the PNG.
* 4) Very low level control over the deflate compression (useful mainly for
* programs that want to try every option to find which gives the smallest
* PNG.)
/* (1) Write compression settings: */
#define png_set_compression(p, v) (png_setting((p), PNG_SW_COMPRESS_png_level,\
0, (v)))
/* Control the write compression of all chunks. This affects five basic
* pieces of behavior:
* 1) The size of the PNG produced.
* 2) The amount of memory the write code takes to produce the PNG.
* 3) The amount of time the write code takes to produce the PNG.
* 4) The amount of memory required to read the resultant PNG.
* 5) The amount of time required to read the resultant PNG.
* There is considerable interdependence between these variables. As a
* result there are a limited number of options:
/* Minimize the memory required both when reading (4) and writing (2) the
* PNG. This results in a significantly larger PNG (which may itself have
* the opposite effect of slowing down either read or write) however the
* memory overhead is reduced and, apart from the extra time to read the
* data, the read time is likely to be reduced too.
* Use this when both read and write will happen on a memory starved
* (really, very low memory) system. Note that this sets a high deflate
* compression setting because that does not affect zlib memory usage.
/* Minimize the time to both read (5) and write (3) the PNG. This uses
* slightly more memory on read and potentially significantly more on
* write but is optimized for maximum speed in both cases.
* Use this when both read and write need to be fast and PNG size is not
* likely to be an issue. An example would be if you are using PNG to
* pass intermediate data between applications on the same machine.
/* Minimize the time to read (5) the PNG. This also reduces the amount
* of memory on read, however some options which require more memory but
* are likely to decrease PNG size, therefore improve read spead, are
* used.
* This is one of the 'normal' options; options that are used when a
* reasonably capable write machine is producing PNG files that will be
* read many times. In this case the option is optimizing for speed on
* read even if it increases the size of the PNG.
/* This switches on options which do affect speed of both compression and
* decompression, but biases the choice towards higher performance in both
* cases. (So it is something of a compromise between all-out speed and
* PNG compression).
* This is a good default to use in typical usages where PNG file size is
* less of an issue than the overheads on reading a PNG file.
* Use this option when producing PNG files that are not expected to be
* distributed widely or where read speed is more important than size.
* This is also a good default for small images where the slight increase
* in size of the compressed data doesn't change the file size much.
/* This is a compromise which switches on the options found most helpful
* across a wide range of files without switching on the full range of
* options which would decrease file size only a little while taking a lot
* more time. PNG read memory (4) or time (5) is not a factor in the
* choice of options; only write time (3).
* This is closest to the default used in prior versions of libpng. There
* seems no logic to using it if the actual requirements are known and,
* even if they aren't, it is probably better to guess 'LOW' or 'HIGH'.
* This is the normal libpng default.
/* This turns on everything which reduces file size on aggregate across a
* large test set of files. It optimizes solely for the size of the
* resultant PNG (1).
* This is a good default to use if file size is all important; it was the
* stated original default in the PNG design, but the implementation of
* libpng never used it.
* Use this setting in image authoring applications when writing the
* finished image in PNG format.
* NOTE: several PNG file size optimizers exist (see the web-site
* libpng does not perform the same functions as these
* optimizers; libpng does not search for the best compression settings.
* For this reason if you really want to minimize the size of the PNG files
* produced use PNG_COMPRESSION_HIGH_SPEED then post-process the result
* with one of the many PNG optimization programs.
/* DEPRECATED: this is provided as a setting to aid transition of test
* suites between major library versions (1.5 or 1.6 moving to 1.7). The
* default settings change in 1.7 so, while the PNG files produced do not
* change, their encoding does. Test systems that rely on constant
* encoding can use this to verify that this is all that has changed.
* NOTE: the option will be removed at some point. It is difficult to
* maintain and adds to libpng code size.
* NOTE: there are other changes in major and minor releases, such as
* better ancillary chunk error handling, that also cause binary changes
* to the PNG files libpng generates. Furthermore versions of libpng
* prior to 1.7 included random data from uninitialized memory in the
* image data under certain circumstances; this meant that earlier
* versions were often not even consistent across two writes of the same
* PNG file!
/* png_set_compression sets the default for all libpng compression operations.
* While the setting is the same for all chunks it results in different
* compression options for different chunks. The setting can be applied
* separately to each class of chunks as follows:
#define png_set_image_compression(p, v) (png_setting((p),\
PNG_SW_COMPRESS_png_level, png_IDAT, (v)))
/* Control the compression of the image data (IDAT) chunks. */
#define png_set_ICC_profile_compression(p, v) (png_setting((p),\
PNG_SW_COMPRESS_png_level, png_iCCP, (v)))
/* Control the compression of ICC profiles (iCCP chunks.) */
#define png_set_text_compression(p, v) (png_setting((p),\
PNG_SW_COMPRESS_png_level, png_zTXt, (v)))
/* Control the compression of text (png_zTXt and png_iTXt) chunks. */
/* (2) IDAT size: */
#define png_set_IDAT_size(p, v) (png_setting((p), PNG_SW_IDAT_size, (v), 0))
/* Set the maximum size of the IDAT chunks libpng writes. Valid values are
* in the range 1U..0x7fffffffU, the default is 'PNG_ZBUF_SIZE' (a
* historically confusing name) and this default *also* controls the size of
* the buffer the read code uses when reading IDAT chunks.
* libpng has to buffer the data in the IDAT chunk before it writes any of
* it, therefore this number directly controls that part of the memory
* overhead while writing a PNG. There is a 12 byte per chunk overhead, so
* the number also directly affects the size of the PNG. The number has no
* significant effect (beyond the latter size effect) on the read code.
#endif /* WRITE */
/* 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 explination of the compression functions.
/* (3) PNG row filters to consider when writing the PNG.
* Control the filtering method(s) used by libpng for the write of subsequent
* rows of the image. The argument is either a single filter value (one of the
* PNG_FILTER_VALUE_ defines above), in which case that filter will be used on
* following rows, or a mask of filter values (logical or of the PNG_FILTER_
* bit masks that follow PNG_FILTER_VALUE_*). Support for selection of a filter
* from a mask with more than one bit set is dependent on
* PNG_SELECT_FILTER_SUPPORTED, however support is the default configuration of
* libpng. If support is not available the lowest bit set in the mask (the
* lowest numbered filter) is used.
* The set of filters may be changed at any time, the new values will affect the
* next row written.
* The 'method' must match that passed to png_set_IHDR; it cannot be changed and
* is ignored in 1.7 and later.
* If multiple filters are enabled libpng will select one according to the
* following rules:
* 1) On the first row of a pass UP is ignored if NONE is set and PAETH is
* ignored if SUB is set; this is because these filter pairs are equivalent
* when there is no previous row.
* If the PNG rows are long enough (have enough bytes) libpng will process a
* row at a time; it will buffer the row if necessary. It uses a heuristic
* based on the closeness of the filtered values to 0 to determine which
* filter to use.
* libpng selects the first filter in the list (there is no warning that this
* will happen - check the #defines if you need to know.)
* The 'up', 'avg' and 'Paeth' filters require the previous image row to work.
* If it is not available they are removed from the set of filters to try. The
* first time the filter mask includes one of these filters libpng turns on
* saving of the row. The filters do work on the first row of a pass, where
* there is no previous row from the image. The PNG standard defines the
* previous row as consisting of all 0 bytes in this case. That definition
* causes the filters to have the following properties on the first row of a
* pass:
* UP: The same as NONE (i.e. no filtering).
* AVG: Uses the arithmetic (not modular arithmetc!) half of the preceding
* pixel as the predictor. This is unique and not typically very
* useful.
* PAETH: The same as SUB.
* As a result with all versions of libpng if you want to use any of these
* filters anywhere in the image you need only turn on one of them on the first
* row of the image, or of a pass for interlaced images. For example if you
* want to use 'sub' on the first row simply set 'sub'+'Paeth' in the mask;
* libpng will automatically eliminate the Paeth algorithm from consideration
* because it knows that 'sub' will rank equal or (if the filter byte is taken
* into account) better.
* This approach is portable to earlier versions of libpng, however it may be
* difficult to program. 1.7 allows you to directly specify whether or not to
* retain the previous row. This is simpler and allows you to turn off previous
* row retention if you want to.
PNG_REMOVED(67, void, png_set_filter, (png_structrp png_ptr, int method,
int filters), PNG_EMPTY)
#define png_set_filter(p, m, f) (png_setting((p), PNG_SW_COMPRESS_filters,\
(m), (f)))
/* 'm' is the method and must be 0 (PNG_FILTER_TYPE_BASE) unless MNG
* processing is supported (very unusual). 'f' is either a single value,
* PNG_FILTER_VALUE_* below, or a combination of one or more PNG_FILTER_MASK
* values.
* This sets the filter mask (or value) for the *next* row that is written.
* It may be called at any time but does not have any effect until the next
* row starts to be written.
* The return value is the mask that is set (or, with PNG_SF_GET, the
* currently set mask). When PNG_SELECT_FILTER_SUPPORTED is not defined this
* mask will have only one bit.
* NOTE: with PNG_SF_GET the result will be PNG_UNSET if png_set_filter has
* not been called before and row writing has not started.
#define png_set_row_buffers(p, onoff) (png_setting((p),\
PNG_SW_COMPRESS_row_buffers, (onoff), 0))
/* If you intend to change the filter list after the first row using the
* previous API call png_set_row_buffers(png_ptr, 1) if you intend to use UP,
* AVG or Paeth filters.
* You can turn the buffering on and off dynamically, just as with
* png_set_filter.
* The second argument should be 0 (off) or 1 (on). In the future it may be
* used to control the maximum number of rows buffered.
#endif /* WRITE_FILTER */
/* The PNG_FILTER_VALUE_ definitions (the filter values from the base PNG spec)
* are valid arguments to png_set_filter() if only a single filter is to be
* used. If multiple filters are to be allowed (the default is to allow any of
* them) then a combination of the following masks must be used and the low
* three bits of the argument to png_set_filter must be 0.
* The resultant argument fits in a single byte in either case.
#define PNG_FILTER_MASK(value) (0x08 << (value))
/* Then three convenience values. PNG_NO_FILTERS is the same as
* PNG_FILTER_VALUE_NONE, but this is harmless because they mean the same thing.
#define PNG_NO_FILTERS 0x00
PNG_REMOVED(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_REMOVED(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),
/* Neither of these API calls did anything in libpng 1.6, however they were
* not marked PNG_DEPRECATED, so they are converted to no-op function-like
* macros here. (NOTE: the macro arguments are evaluated once each, this
* will probably cause warnings with some compiler options: simply remove the
* function call after ensuring that the arguments had no side effects.)
#define png_set_filter_heuristics(p,m,w,fw,fc) ((void)(p,m,w,fw,fc))
#define png_set_filter_heuristics_fixed(p,m,w,fw,fc) ((void)(p,m,w,fw,fc))
PNG_REMOVED(69, void, png_set_compression_level, (png_structrp png_ptr,
int level), PNG_EMPTY)
#define png_set_compression_level(p, v) (png_setting((p),\
PNG_SW_COMPRESS_zlib_level, png_IDAT, (v)))
PNG_REMOVED(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
int mem_level), PNG_EMPTY)
#define png_set_compression_mem_level(p, v) (png_setting((p),\
PNG_SW_COMPRESS_memLevel, png_IDAT, (v)))
PNG_REMOVED(71, void, png_set_compression_strategy, (png_structrp png_ptr,
int strategy), PNG_EMPTY)
#define png_set_compression_strategy(p, v) (png_setting((p),\
PNG_SW_COMPRESS_strategy, png_IDAT, (v)))
PNG_REMOVED(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
int window_bits), PNG_EMPTY)
#define png_set_compression_window_bits(p, v) (png_setting((p),\
PNG_SW_COMPRESS_windowBits, png_IDAT, (v)))
PNG_REMOVED(73, void, png_set_compression_method, (png_structrp png_ptr,
int method), PNG_EMPTY)
#define png_set_compression_method(p, v) (png_setting((p),\
PNG_SW_COMPRESS_method, png_IDAT, (v)))
/* Also set zlib parameters for compressing non-IDAT chunks */
PNG_REMOVED(222, void, png_set_text_compression_level, (png_structrp png_ptr,
int level), PNG_EMPTY)
#define png_set_text_compression_level(p, v) (png_setting((p),\
PNG_SW_COMPRESS_zlib_level, png_zTXt, (v)))
PNG_REMOVED(223, void, png_set_text_compression_mem_level,
(png_structrp png_ptr, int mem_level), PNG_EMPTY)
#define png_set_text_compression_mem_level(p, v) (png_setting((p),\
PNG_SW_COMPRESS_memLevel, png_zTXt, (v)))
PNG_REMOVED(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
int strategy), PNG_EMPTY)
#define png_set_text_compression_strategy(p, v) (png_setting((p),\
PNG_SW_COMPRESS_strategy, png_zTXt, (v)))
PNG_REMOVED(225, void, png_set_text_compression_window_bits,
(png_structrp png_ptr, int window_bits), PNG_EMPTY)
#define png_set_text_compression_window_bits(p, v) (png_setting((p),\
PNG_SW_COMPRESS_windowBits, png_zTXt, (v)))
PNG_REMOVED(226, void, png_set_text_compression_method, (png_structrp png_ptr,
int method), PNG_EMPTY)
#define png_set_text_compression_method(p, v) (png_setting((p),\
PNG_SW_COMPRESS_method, png_zTXt, (v)))
/* NOTE: in versions of libpng prior to 1.7 iCCP compression was controlled by
* the text settings, hence the controls were only available if
* no longer affect iCCP compression, the following macros must be used (if
* necessary):
#define png_set_ICC_profile_compression_level(p, v) (png_setting((p),\
PNG_SW_COMPRESS_zlib_level, png_iCCP, (v)))
#define png_set_ICC_profile_compression_mem_level(p, v) (png_setting((p),\
PNG_SW_COMPRESS_memLevel, png_iCCP, (v)))
#define png_set_ICC_profile_compression_strategy(p, v) (png_setting((p),\
PNG_SW_COMPRESS_strategy, png_iCCP, (v)))
#define png_set_ICC_profile_compression_window_bits(p, v) (png_setting((p),\
PNG_SW_COMPRESS_windowBits, png_iCCP, (v)))
#define png_set_ICC_profile_compression_method(p, v) (png_setting((p),\
PNG_SW_COMPRESS_method, png_iCCP, (v)))
#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.
/* Initialize the input/output for the PNG file to the default functions. */
PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
/* 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));
/* 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));
PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
png_user_transform_ptr read_user_transform_fn));
PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
png_user_transform_ptr write_user_transform_fn));
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));
/* 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));
/* 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 and this is not possible for any chunk
* that affects the image reading (e.g. PLTE, tRNS).
* 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 default unknown handling is used
* (even if this was a chunk that would otherwise be known.)
* NOTE: prior to libpng 1.7 handling values of
* converted to PNG_HANDLE_CHUNK_IF_SAFE (libpng 1.6.0 warns if this
* happens) so it was not possible to discard unknown chunk data if a
* user callback was installed.
* positive: The chunk was handled, libpng will ignore/discard it.
* WARNING: if this callback is set every chunk in the stream is temporarily
* read into a memory buffer. This has potential performance implications,
* particularly for small PNG images with large amounts of ancilliary
* information.
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));
PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
/* 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));
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 responsibility for freeing existing data, whether allocated
* by libpng or by the application; this works on the png_info structure passed
* in, it does not change the state for other png_info structures.
* It is unlikely that this function works correctly as of 1.6.0 and using it
* may result either in memory leaks or double free of allocated data. It was
* removed in libpng 1.7.0.
PNG_REMOVED(99, void, png_data_freer, (png_const_structrp png_ptr,
png_inforp info_ptr, int freer, png_uint_32 mask), PNG_DEPRECATED)
/* Flags for png_free_data */
#define PNG_FREE_HIST 0x0008U
#define PNG_FREE_ICCP 0x0010U
#define PNG_FREE_SPLT 0x0020U
#define PNG_FREE_ROWS 0x0040U
#define PNG_FREE_PCAL 0x0080U
#define PNG_FREE_SCAL 0x0100U
# define PNG_FREE_UNKN 0x0200U
/* PNG_FREE_LIST 0x0400U removed in 1.6.0 because it is ignored */
#define PNG_FREE_PLTE 0x1000U
#define PNG_FREE_TRNS 0x2000U
#define PNG_FREE_TEXT 0x4000U
#define PNG_FREE_ALL 0x7fffU
/* These were deprecated in libpng 1.6.0 and have been removed from libpng
* 1.7.0; the functionality should be accessed by calling malloc or free
* directly or, if png_error handling is required, calling png_malloc.
PNG_REMOVED(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED)
PNG_REMOVED(101, void, png_free_default, (png_const_structrp png_ptr,
png_voidp ptr), PNG_DEPRECATED)
/* 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);
/* 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)
/* 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);
# define png_chunk_error(s1,s2) png_error(s1,s2)
/* 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));
# define png_warning(s1,s2) ((void)(s1))
# define png_chunk_warning(s1,s2) ((void)(s1))
/* 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));
/* 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));
#define png_set_error_action(png_ptr, what, action)\
(png_setting((png_ptr), PNG_SRW_ERROR_HANDLING, (what), (action)))
/* Control the handling of 'benign' errors; errors that can be handled in
* some way. The action is one of the following values:
#define PNG_IGNORE 0 /* ignore the error; no warning or error message */
#define PNG_WARN 1 /* call png_warning with an appropriate error message */
#define PNG_ERROR 2 /* call png_error with the error message */
/* 'what' is a list (bit mask) of the errors to set: */
#define PNG_APP_ERRORS (4U)
#define PNG_IDAT_ERRORS (8U)
PNG_REMOVED(109, void, png_set_benign_errors,
(png_structrp png_ptr, int allowed), PNG_EMPTY)
#define png_set_benign_errors(png_ptr, allowed) (png_setting((png_ptr),\
(allowed) ? PNG_WARN : PNG_ERROR))
/* Turn all errors that can be handled into warnings, or turn them back into
* errors if 'allowed' is false.
# define png_benign_error(pp,e) png_warning(pp,e)
# define png_chunk_benign_error(pp,e) png_chunk_warning(pp,e)
# else
# define png_benign_error(pp,e) png_error(pp,e)
# define png_chunk_benign_error(pp,e) png_chunk_error(pp,e)
# 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, png_alloc_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* 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));
/* 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));
/* 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 */
/* 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));
PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
png_inforp info_ptr, png_color_16p *background));
PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_color_16p background));
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))
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))
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))
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))
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));
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));
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));
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));
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));
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));
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));
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));
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));
PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_color_8p *sig_bit));
PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_color_8p sig_bit));
PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
png_const_inforp info_ptr, int *file_srgb_intent));
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));
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));
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));
PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_sPLT_tpp entries));
PNG_EXPORT(161, void, png_set_sPLT, (png_structrp png_ptr,
png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
/* 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));
/* 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.
PNG_EXPORT(163, void, png_set_text, (png_structrp png_ptr,
png_inforp info_ptr, png_const_textp text_ptr, int num_text));
PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
png_inforp info_ptr, png_timep *mod_time));
PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_timep mod_time));
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));
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));
/* NOTE: these API are currently implemented using floating point arithmetic,
* consequently they 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_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))
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))
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));
/* This also requires internal floating point arithmetic support - i.e. it
* requires a full math library, not just floating point handling.
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 */
/* 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 implement the
* desired handling (keep or discard.)
* NOTE: prior to 1.7.0 when a user callback returned '0', indicating that the
* chunk had not been handled, libpng would preserve it regardless of the
* default or per-chunk settings. For compatibility with earlier versions
* simply return '1' (handled) from the callback to discard the chunk.
* The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below. The
* parameter is interpreted as follows:
* 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.
* Discard the chunk data.
* Keep the chunk data if the chunk is not critical else raise a chunk
* error.
* 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.
* 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.)
* 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!
* 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:
* Write safe-to-copy chunks and write other chunks if the global
* default is set to _ALWAYS, otherwise don't write this chunk.
* Do not write the chunk.
* Write the chunk if it is safe-to-copy, otherwise do not write it.
* 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.
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));
PNG_EXPORT(174, void, png_set_unknown_chunks, (png_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.
* API CHANGE: in 1.7.0 this API will not work on read unless
* PNG_SAVE_UNKNOWN_CHUNKS_SUPPORTED is set; it may be necessary to change
* code to check the latter SUPPORTED flag. png_set_keep_unknown_chunks
* will issue a warning if it is asked to save a chunk and there is no read
* support.
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));
/* 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));
/* The "params" pointer is currently not used and is for future expansion. */
PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
int transforms, png_voidp params));
PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
int transforms, png_voidp params));
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));
PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
png_uint_32 mng_features_permitted));
/* For use in png_set_keep_unknown, added to version 1.2.6 */
/* This was never implemented: */
PNG_REMOVED(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
png_uint_32 strip_mode), PNG_EMPTY)
/* Added in libpng-1.2.6 */
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));
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))
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))
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 */
/* Added in libpng-1.4.0 */
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_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 0x0000U /* no I/O at this moment */
# define PNG_IO_READING 0x0001U /* currently reading */
# define PNG_IO_WRITING 0x0002U /* currently writing */
# define PNG_IO_SIGNATURE 0x0010U /* currently at the file signature */
# define PNG_IO_CHUNK_HDR 0x0020U /* currently at the chunk header */
# define PNG_IO_CHUNK_DATA 0x0040U /* currently at the chunk data */
# define PNG_IO_CHUNK_CRC 0x0080U /* currently at the chunk crc */
# define PNG_IO_MASK_OP 0x000fU /* current operation: reading/writing */
# define PNG_IO_MASK_LOC 0x00f0U /* 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.
/* 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 3-log2 of the number or
* rows or columns in each 8x8 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))\
#define PNG_PASS_COLS(width, pass) (((width)+(((1<<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) \
#define PNG_COL_FROM_PASS_COL(x_in, 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) ( \
((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
#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)
/* Whether the pass is in the image at all, taking into account the full image
* width and height, evaluates 'pass' lots of times, but width and height at
* most once each.
#define PNG_PASS_IN_IMAGE(width, height, pass)\
((height) > PNG_PASS_START_ROW(pass) && (width) > PNG_PASS_START_COL(pass))
/* A macro to find the last pass (in the range 0 to 6) given an image width and
* height. Then two macros two find whether a given image row or column which
* is present in the pass is the last row or column in the pass. Note that
* these macros return 'true' for earlier rows or columns of the image that are
* *not* in the pass.
#define PNG_LAST_PASS(width, height) ((height) > 1 ? 6 : ((width) > 1 ? 5 : 0))
#define PNG_LAST_PASS_ROW(y, pass, height)\
((y) + PNG_PASS_ROW_OFFSET(pass) >= (height))
#define PNG_LAST_PASS_COL(x, pass, width)\
((x) + PNG_PASS_COL_OFFSET(pass) >= (width))
/* 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); }
# 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)((temp + (temp >> 16)) >> 16); }
#else /* Standard method using integer division */
# define png_composite(composite, fg, alpha, bg) \
(composite) = (png_byte)(((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)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
(png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) + \
32767) / 65535)
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));
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). */
PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
/* This becomes a macro in 1.7 because the old implementation was wrong; it
* failed to do the cast. ANSI C requires the cast to convert a negative number
* to the 2's complement form, so this just works:
#define png_save_int_32(b, i) png_save_uint_32(b, i);
/* Apps that used this will use the macro in 1.7. */
PNG_REMOVED(206, void, png_save_int_32, (png_bytep buf, png_int_32 i),
/* 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.
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. */
/* Inline macros to do direct reads of bytes from the input buffer.
# define PNG_B(ptr, offset) (((png_const_bytep)(ptr))[offset])
# define PNG_get_uint_32(buf) \
PNG_U32(PNG_B(buf,0), PNG_B(buf,1), PNG_B(buf,2), PNG_B(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_U16(PNG_B(buf,0), PNG_B(buf,1))
# define PNG_get_int_32(buf) \
PNG_S32(PNG_B(buf,0), PNG_B(buf,1), PNG_B(buf,2), PNG_B(buf,3))
/* 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
# 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
PNG_REMOVED(242, void, png_set_check_for_invalid_index,
(png_structrp png_ptr, int enabled_if_greater_than_0), PNG_EMPTY)
#define png_set_check_for_invalid_index(png_ptr, value)\
(png_setting((png_ptr), PNG_SRW_CHECK_FOR_INVALID_INDEX, 0, (value)))
/* By default the check is enabled on both read and write when the number of
* entries in the palette is less than the maximum required by the bit depth
* of a palette image.
* Passing 1 to 'enabled' turns the check on in all cases.
* Passing -1 turns it off and the PNG may have invalid palette index values.
* Passing 0 restores the default.
* On read chunk (benign) error messages are only produced with the default
* setting; it is assumed that when the check is turned on explicitly the
* caller will call png_get_palette_max to check the result.
* The png_setting call returns 0.
PNG_EXPORT(243, int, png_get_palette_max, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* The info_ptr is not used, it may be NULL in 1.7.0 (not in earlier
* versions). If the information is not available because
* png_set_check_for_invalid_index was not used to turn it on -1 is returned.
* Valid results can only be obtained after the complete image has been read,
* though it may be called at any time to get the result so far.
#endif /* GET_PALETTE_MAX */
/* Memory format options; these return information about the layout of the
* transformed row using the Simplified API PNG_FORMAT_ values (see below for
* the #defines).
* These are only relevant if read or write transforms are supported; these
* may cause the memory format of pixel data to differ from that used in the
* PNG file itself. Nevertheless the APIs are supported regardless of whether
* transforms are applied; use these to consistently and safely determine the
* layout of the image in memory.
* Some of the same information can be obtained from png_info, however this
* does not record whether the byte or bit formats have been changed.
PNG_EXPORT(246, unsigned int, png_memory_format, (png_structrp png_ptr));
/* The in-memory format as a bitmask of PNG_FORMAT_FLAG_ values. All the
* flags listed below are used. If PNG_FORMAT_FLAG_INVALID is set the
* following caveats apply to the interpretation of PNG_FORMAT_FLAG_LINEAR:
* The gamma may differ from the sRGB (!LINEAR) or 1.0 (LINEAR). Call
* png_memory_gamma to find the correct value.
* The channel depth may differ from 8 (!LINEAR) or 16 (LINEAR). Call
* png_memory_channel_depth to find the correct value.
* It is only valid to call these APIS *after* either png_read_update_info
* or png_start_read_image on read or after the first row of an image has
* been written on write.
* To find the number of channels in each pixel from the returned value,
* 'fmt' use:
PNG_EXPORT(247, unsigned int, png_memory_channel_depth, (png_structrp png_ptr));
/* The actual depth of each channel in the image, to determine the full pixel
* depth (in bits) use:
* png_memory_channel_depth(pp) * PNG_FORMAT_CHANNELS(fmt)
PNG_EXPORT(248, png_fixed_point, png_memory_gamma, (png_structrp png_ptr));
/* The actual gamma of the image data, scaled by 100,000. This is the
* encoding gamma, e.g. 1/2.2 for sRGB. If the gamma is unknown this will
* return 0.
* On write this invariably returns 0; libpng does not change the gamma of
* the data on write.
* Note that this is not always the exact inverse of the 'screen gamma'
* passed to png_set_gamma; internal optimizations remove attempts to make
* small changes to the gamma value. This function returns the actual
* output value.
#endif /* GAMMA */
* 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 accomodate 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 and set the
* version field to PNG_IMAGE_VERSION.
* 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:
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.