/* png.h - header file for PNG reference library

 *

 * libpng version 1.6.21, January 15, 2016

 *

 * Copyright (c) 1998-2002,2004,2006-2016 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 1.6.21, January 15, 2016:

 *     Glenn Randers-Pehrson.

 *   See also "Contributing Authors", below.

 */

/*

 * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:

 *

 * 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 1.6.21, January 15, 2016, are

 * Copyright (c) 2000-2002, 2004, 2006-2016 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.

 *

 * 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

 *

 * libpng versions 0.5, May 1995, through 0.88, January 1996, are

 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.

 *

 * For the purposes of this copyright and license, "Contributing Authors"

 * is defined as the following set of individuals:

 *

 *    Andreas Dilger

 *    Dave Martindale

 *    Guy Eric Schalnat

 *    Paul Schmidt

 *    Tim Wegner

 *

 * The PNG Reference Library is supplied "AS IS".  The Contributing Authors

 * and Group 42, Inc. disclaim all warranties, expressed or implied,

 * including, without limitation, the warranties of merchantability and of

 * fitness for any purpose.  The Contributing Authors and Group 42, Inc.

 * assume no liability for direct, indirect, incidental, special, exemplary,

 * or consequential damages, which may result from the use of the PNG

 * Reference Library, even if advised of the possibility of such damage.

 *

 * Permission is hereby granted to use, copy, modify, and distribute this

 * source code, or portions hereof, for any purpose, without fee, subject

 * to the following restrictions:

 *

 *   1. The origin of this source code must not be misrepresented.

 *

 *   2. Altered versions must be plainly marked as such and must not

 *      be misrepresented as being the original source.

 *

 *   3. This Copyright notice may not be removed or altered from any

 *      source or altered source distribution.

 *

 * The Contributing Authors and Group 42, Inc. specifically permit, without

 * fee, and encourage the use of this source code as a component to

 * supporting the PNG file format in commercial products.  If you use this

 * source code in a product, acknowledgment is not required but would be

 * appreciated.

 *

 * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.

 */

/*

 * 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).

 */

/*

 * 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 contributing authors would like to thank all those who helped

 * with testing, bug fixes, and patience.  This wouldn't have been

 * possible without all of you.

 *

 * Thanks to Frank J. T. Wojcik for helping with the documentation.

 */

/* Note about libpng version numbers:

 *

 *    Due to various miscommunications, unforeseen code incompatibilities

 *    and occasional factors outside the authors' control, version numbering

 *    on the library has not always been consistent and straightforward.

 *    The following table summarizes matters since version 0.89c, which was

 *    the first widely used release:

 *

 *    source                 png.h  png.h  shared-lib

 *    version                string   int  version

 *    -------                ------ -----  ----------

 *    0.89c "1.0 beta 3"     0.89      89  1.0.89

 *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]

 *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]

 *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]

 *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]

 *    0.97c                  0.97      97  2.0.97

 *    0.98                   0.98      98  2.0.98

 *    0.99                   0.99      98  2.0.99

 *    0.99a-m                0.99      99  2.0.99

 *    1.00                   1.00     100  2.1.0 [100 should be 10000]

 *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]

 *    1.0.1       png.h string is   10001  2.1.0

 *    1.0.1a-e    identical to the  10002  from here on, the shared library

 *    1.0.2       source version)   10002  is 2.V where V is the source code

 *    1.0.2a-b                      10003  version, except as noted.

 *    1.0.3                         10003

 *    1.0.3a-d                      10004

 *    1.0.4                         10004

 *    1.0.4a-f                      10005

 *    1.0.5 (+ 2 patches)           10005

 *    1.0.5a-d                      10006

 *    1.0.5e-r                      10100 (not source compatible)

 *    1.0.5s-v                      10006 (not binary compatible)

 *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)

 *    1.0.6d-f                      10007 (still binary incompatible)

 *    1.0.6g                        10007

 *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)

 *    1.0.6i                        10007  10.6i

 *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)

 *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)

 *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)

 *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)

 *    1.0.7                    1    10007  (still compatible)

 *    ...

 *    1.0.19                  10    10019  10.so.0.19[.0]

 *    ...

 *    1.2.53                  13    10253  12.so.0.53[.0]

 *    ...

 *    1.5.23                  15    10523  15.so.15.23[.0]

 *    ...

 *    1.6.21                  16    10621  16.so.16.21[.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:

 * =========================

 *

 *    January 15, 2016

 *

 *    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 1.6.21 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

 * <http: libpng-manual.txt="" png="" pub="" www.libpng.org=""></http:>

 *

 * If you just need to read a PNG file and don't want to read the documentation

 * skip to the end of this file and read the section entitled 'simplified API'.

 */

/* Version information for png.h - this should match the version in png.c */

#define PNG_LIBPNG_VER_STRING "1.6.21"

#define PNG_HEADER_VERSION_STRING \

     " libpng version 1.6.21 - January 15, 2016\n"

#define PNG_LIBPNG_VER_SONUM   16

#define PNG_LIBPNG_VER_DLLNUM  16

/* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */

#define PNG_LIBPNG_VER_MAJOR   1

#define PNG_LIBPNG_VER_MINOR   6

#define PNG_LIBPNG_VER_RELEASE 21

/* This should match the numeric part of the final component of

 * PNG_LIBPNG_VER_STRING, omitting any leading zero:

 */

#define PNG_LIBPNG_VER_BUILD  0

/* Release Status */

#define PNG_LIBPNG_BUILD_ALPHA    1

#define PNG_LIBPNG_BUILD_BETA     2

#define PNG_LIBPNG_BUILD_RC       3

#define PNG_LIBPNG_BUILD_STABLE   4

#define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7

/* Release-Specific Flags */

#define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with

                                       PNG_LIBPNG_BUILD_STABLE only */

#define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with

                                       PNG_LIBPNG_BUILD_SPECIAL */

#define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with

                                       PNG_LIBPNG_BUILD_PRIVATE */

#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE

/* Careful here.  At one time, Guy wanted to use 082, but that would be octal.

 * We must not include leading zeros.

 * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only

 * version 1.0.0 was mis-numbered 100 instead of 10000).  From

 * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release

 */

#define PNG_LIBPNG_VER 10621 /* 1.6.21 */

/* Library configuration: these options cannot be changed after

 * the library has been built.

 */

#ifndef PNGLCONF_H

    /* If pnglibconf.h is missing, you can

     * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h

     */

#   include "pnglibconf.h"

#endif

#ifndef PNG_VERSION_INFO_ONLY

   /* Machine specific configuration. */

#  include "pngconf.h"

#endif

/*

 * Added at libpng-1.2.8

 *

 * Ref MSDN: Private as priority over Special

 * VS_FF_PRIVATEBUILD File *was not* built using standard release

 * procedures. If this value is given, the StringFileInfo block must

 * contain a PrivateBuild string.

 *

 * VS_FF_SPECIALBUILD File *was* built by the original company using

 * standard release procedures but is a variation of the standard

 * file of the same version number. If this value is given, the

 * StringFileInfo block must contain a SpecialBuild string.

 */

#ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */

#  define PNG_LIBPNG_BUILD_TYPE \

       (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)

#else

#  ifdef PNG_LIBPNG_SPECIALBUILD

#    define PNG_LIBPNG_BUILD_TYPE \

         (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)

#  else

#    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)

#  endif

#endif

#ifndef PNG_VERSION_INFO_ONLY

/* Inhibit C++ name-mangling for libpng functions but not for system calls. */

#ifdef __cplusplus

extern "C" {

#endif /* __cplusplus */

/* Version information for C files, stored in png.c.  This had better match

 * the version above.

 */

#define png_libpng_ver png_get_header_ver(NULL)

/* This file is arranged in several sections:

 *

 * 1. [omitted]

 * 2. Any configuration options that can be specified by for the application

 *    code when it is built.  (Build time configuration is in pnglibconf.h)

 * 3. Type definitions (base types are defined in pngconf.h), structure

 *    definitions.

 * 4. Exported library functions.

 * 5. Simplified API.

 * 6. Implementation options.

 *

 * The library source code has additional files (principally pngpriv.h) that

 * allow configuration of the library.

 */

/* Section 1: [omitted] */

/* Section 2: run time configuration

 * See pnglibconf.h for build time configuration

 *

 * Run time configuration allows the application to choose between

 * implementations of certain arithmetic APIs.  The default is set

 * at build time and recorded in pnglibconf.h, but it is safe to

 * override these (and only these) settings.  Note that this won't

 * change what the library does, only application code, and the

 * settings can (and probably should) be made on a per-file basis

 * by setting the #defines before including png.h

 *

 * Use macros to read integers from PNG data or use the exported

 * functions?

 *   PNG_USE_READ_MACROS: use the macros (see below)  Note that

 *     the macros evaluate their argument multiple times.

 *   PNG_NO_USE_READ_MACROS: call the relevant library function.

 *

 * Use the alternative algorithm for compositing alpha samples that

 * does not use division?

 *   PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'

 *      algorithm.

 *   PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.

 *

 * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is

 * false?

 *   PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error

 *      APIs to png_warning.

 * Otherwise the calls are mapped to png_error.

 */

/* Section 3: type definitions, including structures and compile time

 * constants.

 * See pngconf.h for base types that vary by machine/system

 */

/* This triggers a compiler error in png.c, if png.c and png.h

 * do not agree upon the version number.

 */

typedef char* png_libpng_version_1_6_21;

/* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.

 *

 * png_struct is the cache of information used while reading or writing a single

 * PNG file.  One of these is always required, although the simplified API

 * (below) hides the creation and destruction of it.

 */

typedef struct png_struct_def png_struct;

typedef const png_struct * png_const_structp;

typedef png_struct * png_structp;

typedef png_struct * * png_structpp;

/* png_info contains information read from or to be written to a PNG file.  One

 * or more of these must exist while reading or creating a PNG file.  The

 * information is not used by libpng during read but is used to control what

 * gets written when a PNG file is created.  "png_get_" function calls read

 * information during read and "png_set_" functions calls write information

 * when creating a PNG.

 * been moved into a separate header file that is not accessible to

 * applications.  Read libpng-manual.txt or libpng.3 for more info.

 */

typedef struct png_info_def png_info;

typedef png_info * png_infop;

typedef const png_info * png_const_infop;

typedef png_info * * png_infopp;

/* Types with names ending 'p' are pointer types.  The corresponding types with

 * names ending 'rp' are identical pointer types except that the pointer is

 * marked 'restrict', which means that it is the only pointer to the object

 * passed to the function.  Applications should not use the 'restrict' types;

 * it is always valid to pass 'p' to a pointer with a function argument of the

 * corresponding 'rp' type.  Different compilers have different rules with

 * regard to type matching in the presence of 'restrict'.  For backward

 * compatibility libpng callbacks never have 'restrict' in their parameters and,

 * consequentially, writing portable application code is extremely difficult if

 * an attempt is made to use 'restrict'.

 */

typedef png_struct * PNG_RESTRICT png_structrp;

typedef const png_struct * PNG_RESTRICT png_const_structrp;

typedef png_info * PNG_RESTRICT png_inforp;

typedef const png_info * PNG_RESTRICT png_const_inforp;

/* Three color definitions.  The order of the red, green, and blue, (and the

 * exact size) is not important, although the size of the fields need to

 * be png_byte or png_uint_16 (as defined below).

 */

typedef struct png_color_struct

{

   png_byte red;

   png_byte green;

   png_byte blue;

} png_color;

typedef png_color * png_colorp;

typedef const png_color * png_const_colorp;

typedef png_color * * png_colorpp;

typedef struct png_color_16_struct

{

   png_byte index;    /* used for palette files */

   png_uint_16 red;   /* for use in red green blue files */

   png_uint_16 green;

   png_uint_16 blue;

   png_uint_16 gray;  /* for use in grayscale files */

} png_color_16;

typedef png_color_16 * png_color_16p;

typedef const png_color_16 * png_const_color_16p;

typedef png_color_16 * * png_color_16pp;

typedef struct png_color_8_struct

{

   png_byte red;   /* for use in red green blue files */

   png_byte green;

   png_byte blue;

   png_byte gray;  /* for use in grayscale files */

   png_byte alpha; /* for alpha channel files */

} png_color_8;

typedef png_color_8 * png_color_8p;

typedef const png_color_8 * png_const_color_8p;

typedef png_color_8 * * png_color_8pp;

/*

 * The following two structures are used for the in-core representation

 * of sPLT chunks.

 */

typedef struct png_sPLT_entry_struct

{

   png_uint_16 red;

   png_uint_16 green;

   png_uint_16 blue;

   png_uint_16 alpha;

   png_uint_16 frequency;

} png_sPLT_entry;

typedef png_sPLT_entry * png_sPLT_entryp;

typedef const png_sPLT_entry * png_const_sPLT_entryp;

typedef png_sPLT_entry * * png_sPLT_entrypp;

/*  When the depth of the sPLT palette is 8 bits, the color and alpha samples

 *  occupy the LSB of their respective members, and the MSB of each member

 *  is zero-filled.  The frequency member always occupies the full 16 bits.

 */

typedef struct png_sPLT_struct

{

   png_charp name;           /* palette name */

   png_byte depth;           /* depth of palette samples */

   png_sPLT_entryp entries;  /* palette entries */

   png_int_32 nentries;      /* number of palette entries */

} png_sPLT_t;

typedef png_sPLT_t * png_sPLT_tp;

typedef const png_sPLT_t * png_const_sPLT_tp;

typedef png_sPLT_t * * png_sPLT_tpp;

#ifdef PNG_TEXT_SUPPORTED

/* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,

 * and whether that contents is compressed or not.  The "key" field

 * points to a regular zero-terminated C string.  The "text" fields can be a

 * regular C string, an empty string, or a NULL pointer.

 * However, the structure returned by png_get_text() will always contain

 * the "text" field as a regular zero-terminated C string (possibly

 * empty), never a NULL pointer, so it can be safely used in printf() and

 * other string-handling functions.  Note that the "itxt_length", "lang", and

 * "lang_key" members of the structure only exist when the library is built

 * with iTXt chunk support.  Prior to libpng-1.4.0 the library was built by

 * default without iTXt support. Also note that when iTXt *is* supported,

 * the "lang" and "lang_key" fields contain NULL pointers when the

 * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or

 * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the

 * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"

 * which is always 0 or 1, or its "compression method" which is always 0.

 */

typedef struct png_text_struct

{

   int  compression;       /* compression value:

                             -1: tEXt, none

                              0: zTXt, deflate

                              1: iTXt, none

                              2: iTXt, deflate  */

   png_charp key;          /* keyword, 1-79 character description of "text" */

   png_charp text;         /* comment, may be an empty string (ie "")

                              or a NULL pointer */

   png_size_t text_length; /* length of the text string */

   png_size_t itxt_length; /* length of the itxt string */

   png_charp lang;         /* language code, 0-79 characters

                              or a NULL pointer */

   png_charp lang_key;     /* keyword translated UTF-8 string, 0 or more

                              chars or a NULL pointer */

} png_text;

typedef png_text * png_textp;

typedef const png_text * png_const_textp;

typedef png_text * * png_textpp;

#endif

/* Supported compression types for text in PNG files (tEXt, and zTXt).

 * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */

#define PNG_TEXT_COMPRESSION_NONE_WR -3

#define PNG_TEXT_COMPRESSION_zTXt_WR -2

#define PNG_TEXT_COMPRESSION_NONE    -1

#define PNG_TEXT_COMPRESSION_zTXt     0

#define PNG_ITXT_COMPRESSION_NONE     1

#define PNG_ITXT_COMPRESSION_zTXt     2

#define PNG_TEXT_COMPRESSION_LAST     3  /* Not a valid value */

/* png_time is a way to hold the time in an machine independent way.

 * Two conversions are provided, both from time_t and struct tm.  There

 * is no portable way to convert to either of these structures, as far

 * as I know.  If you know of a portable way, send it to me.  As a side

 * note - PNG has always been Year 2000 compliant!

 */

typedef struct png_time_struct

{

   png_uint_16 year; /* full year, as in, 1995 */

   png_byte month;   /* month of year, 1 - 12 */

   png_byte day;     /* day of month, 1 - 31 */

   png_byte hour;    /* hour of day, 0 - 23 */

   png_byte minute;  /* minute of hour, 0 - 59 */

   png_byte second;  /* second of minute, 0 - 60 (for leap seconds) */

} png_time;

typedef png_time * png_timep;

typedef const png_time * png_const_timep;

typedef png_time * * png_timepp;

#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\

   defined(PNG_USER_CHUNKS_SUPPORTED)

/* png_unknown_chunk is a structure to hold queued chunks for which there is

 * no specific support.  The idea is that we can use this to queue

 * up private chunks for output even though the library doesn't actually

 * know about their semantics.

 *

 * The data in the structure is set by libpng on read and used on write.

 */

typedef struct png_unknown_chunk_t

{

    png_byte name[5]; /* Textual chunk name with '\0' terminator */

    png_byte *data;   /* Data, should not be modified on read! */

    png_size_t size;

    /* On write 'location' must be set using the flag values listed below.

     * Notice that on read it is set by libpng however the values stored have

     * more bits set than are listed below.  Always treat the value as a

     * bitmask.  On write set only one bit - setting multiple bits may cause the

     * chunk to be written in multiple places.

     */

    png_byte location; /* mode of operation at read time */

}

png_unknown_chunk;

typedef png_unknown_chunk * png_unknown_chunkp;

typedef const png_unknown_chunk * png_const_unknown_chunkp;

typedef png_unknown_chunk * * png_unknown_chunkpp;

#endif

/* Flag values for the unknown chunk location byte. */

#define PNG_HAVE_IHDR  0x01

#define PNG_HAVE_PLTE  0x02

#define PNG_AFTER_IDAT 0x08

/* Maximum positive integer used in PNG is (2^31)-1 */

#define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)

#define PNG_UINT_32_MAX ((png_uint_32)(-1))

#define PNG_SIZE_MAX ((png_size_t)(-1))

/* These are constants for fixed point values encoded in the

 * PNG specification manner (x100000)

 */

#define PNG_FP_1    100000

#define PNG_FP_HALF  50000

#define PNG_FP_MAX  ((png_fixed_point)0x7fffffffL)

#define PNG_FP_MIN  (-PNG_FP_MAX)

/* These describe the color_type field in png_info. */

/* color type masks */

#define PNG_COLOR_MASK_PALETTE    1

#define PNG_COLOR_MASK_COLOR      2

#define PNG_COLOR_MASK_ALPHA      4

/* color types.  Note that not all combinations are legal */

#define PNG_COLOR_TYPE_GRAY 0

#define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)

#define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)

#define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)

#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)

/* aliases */

#define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA

#define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA

/* This is for compression type. PNG 1.0-1.2 only define the single type. */

#define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */

#define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE

/* This is for filter type. PNG 1.0-1.2 only define the single type. */

#define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */

#define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */

#define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE

/* These are for the interlacing type.  These values should NOT be changed. */

#define PNG_INTERLACE_NONE        0 /* Non-interlaced image */

#define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */

#define PNG_INTERLACE_LAST        2 /* Not a valid value */

/* These are for the oFFs chunk.  These values should NOT be changed. */

#define PNG_OFFSET_PIXEL          0 /* Offset in pixels */

#define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */

#define PNG_OFFSET_LAST           2 /* Not a valid value */

/* These are for the pCAL chunk.  These values should NOT be changed. */

#define PNG_EQUATION_LINEAR       0 /* Linear transformation */

#define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */

#define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */

#define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */

#define PNG_EQUATION_LAST         4 /* Not a valid value */

/* These are for the sCAL chunk.  These values should NOT be changed. */

#define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */

#define PNG_SCALE_METER           1 /* meters per pixel */

#define PNG_SCALE_RADIAN          2 /* radians per pixel */

#define PNG_SCALE_LAST            3 /* Not a valid value */

/* These are for the pHYs chunk.  These values should NOT be changed. */

#define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */

#define PNG_RESOLUTION_METER      1 /* pixels/meter */

#define PNG_RESOLUTION_LAST       2 /* Not a valid value */

/* These are for the sRGB chunk.  These values should NOT be changed. */

#define PNG_sRGB_INTENT_PERCEPTUAL 0

#define PNG_sRGB_INTENT_RELATIVE   1

#define PNG_sRGB_INTENT_SATURATION 2

#define PNG_sRGB_INTENT_ABSOLUTE   3

#define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */

/* This is for text chunks */

#define PNG_KEYWORD_MAX_LENGTH     79

/* Maximum number of entries in PLTE/sPLT/tRNS arrays */

#define PNG_MAX_PALETTE_LENGTH    256

/* These determine if an ancillary chunk's data has been successfully read

 * from the PNG header, or if the application has filled in the corresponding

 * data in the info_struct to be written into the output file.  The values

 * of the PNG_INFO_<chunk> defines should NOT be changed.</chunk>

 */

#define PNG_INFO_gAMA 0x0001

#define PNG_INFO_sBIT 0x0002

#define PNG_INFO_cHRM 0x0004

#define PNG_INFO_PLTE 0x0008

#define PNG_INFO_tRNS 0x0010

#define PNG_INFO_bKGD 0x0020

#define PNG_INFO_hIST 0x0040

#define PNG_INFO_pHYs 0x0080

#define PNG_INFO_oFFs 0x0100

#define PNG_INFO_tIME 0x0200

#define PNG_INFO_pCAL 0x0400

#define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */

#define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */

#define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */

#define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */

#if INT_MAX >= 0x8000 /* else this might break */

#define PNG_INFO_IDAT 0x8000   /* ESR, 1.0.6 */

#endif

/* This is used for the transformation routines, as some of them

 * change these values for the row.  It also should enable using

 * the routines for other purposes.

 */

typedef struct png_row_info_struct

{

   png_uint_32 width;    /* width of row */

   png_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, png_size_t));

typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));

typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,

    int));

typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,

    int));

#ifdef PNG_PROGRESSIVE_READ_SUPPORTED

typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));

typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));

/* The following callback receives png_uint_32 row_number, int pass for the

 * png_bytep data of the row.  When transforming an interlaced image the

 * row number is the row number within the sub-image of the interlace pass, so

 * the value will increase to the height of the sub-image (not the full image)

 * then reset to 0 for the next pass.

 *

 * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to

 * find the output pixel (x,y) given an interlaced sub-image pixel

 * (row,col,pass).  (See below for these macros.)

 */

typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,

    png_uint_32, int));

#endif

#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \

    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)

typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,

    png_bytep));

#endif

#ifdef PNG_USER_CHUNKS_SUPPORTED

typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,

    png_unknown_chunkp));

#endif

#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED

/* not used anywhere */

/* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */

#endif

#ifdef PNG_SETJMP_SUPPORTED

/* This must match the function definition in <setjmp.h>, and the application</setjmp.h>

 * 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);

#endif

/* Transform masks for the high-level interface */

#define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */

#define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */

#define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */

#define PNG_TRANSFORM_PACKING        0x0004    /* read and write */

#define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */

#define PNG_TRANSFORM_EXPAND         0x0010    /* read only */

#define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */

#define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */

#define PNG_TRANSFORM_BGR            0x0080    /* read and write */

#define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */

#define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */

#define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */

#define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* write only */

/* Added to libpng-1.2.34 */

#define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER

#define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */

/* Added to libpng-1.4.0 */

#define PNG_TRANSFORM_GRAY_TO_RGB   0x2000      /* read only */

/* Added to libpng-1.5.4 */

#define PNG_TRANSFORM_EXPAND_16     0x4000      /* read only */

#if INT_MAX >= 0x8000 /* else this might break */

#define PNG_TRANSFORM_SCALE_16      0x8000      /* read only */

#endif

/* Flags for MNG supported features */

#define PNG_FLAG_MNG_EMPTY_PLTE     0x01

#define PNG_FLAG_MNG_FILTER_64      0x04

#define PNG_ALL_MNG_FEATURES        0x05

/* NOTE: prior to 1.5 these functions had no 'API' style declaration,

 * this allowed the zlib default functions to be used on Windows

 * platforms.  In 1.5 the zlib default malloc (which just calls malloc and

 * ignores the first argument) should be completely compatible with the

 * following.

 */

typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,

    png_alloc_size_t));

typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));

/* Section 4: exported functions

 * Here are the function definitions most commonly used.  This is not

 * the place to find out how to use libpng.  See libpng-manual.txt for the