2 /* png.h - header file for PNG reference library
4 * libpng version 1.6.2 - April 25, 2013
5 * Copyright (c) 1998-2013 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9 * This code is released under the libpng license (See LICENSE, below)
11 * Authors and maintainers:
12 * libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
13 * libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
14 * libpng versions 0.97, January 1998, through 1.6.2 - April 25, 2013: Glenn
15 * See also "Contributing Authors", below.
17 * Note about libpng version numbers:
19 * Due to various miscommunications, unforeseen code incompatibilities
20 * and occasional factors outside the authors' control, version numbering
21 * on the library has not always been consistent and straightforward.
22 * The following table summarizes matters since version 0.89c, which was
23 * the first widely used release:
25 * source png.h png.h shared-lib
26 * version string int version
27 * ------- ------ ----- ----------
28 * 0.89c "1.0 beta 3" 0.89 89 1.0.89
29 * 0.90 "1.0 beta 4" 0.90 90 0.90 [should have been 2.0.90]
30 * 0.95 "1.0 beta 5" 0.95 95 0.95 [should have been 2.0.95]
31 * 0.96 "1.0 beta 6" 0.96 96 0.96 [should have been 2.0.96]
32 * 0.97b "1.00.97 beta 7" 1.00.97 97 1.0.1 [should have been 2.0.97]
33 * 0.97c 0.97 97 2.0.97
36 * 0.99a-m 0.99 99 2.0.99
37 * 1.00 1.00 100 2.1.0 [100 should be 10000]
38 * 1.0.0 (from here on, the 100 2.1.0 [100 should be 10000]
39 * 1.0.1 png.h string is 10001 2.1.0
40 * 1.0.1a-e identical to the 10002 from here on, the shared library
41 * 1.0.2 source version) 10002 is 2.V where V is the source code
42 * 1.0.2a-b 10003 version, except as noted.
47 * 1.0.5 (+ 2 patches) 10005
49 * 1.0.5e-r 10100 (not source compatible)
50 * 1.0.5s-v 10006 (not binary compatible)
51 * 1.0.6 (+ 3 patches) 10006 (still binary incompatible)
52 * 1.0.6d-f 10007 (still binary incompatible)
54 * 1.0.6h 10007 10.6h (testing xy.z so-numbering)
56 * 1.0.6j 10007 2.1.0.6j (incompatible with 1.0.0)
57 * 1.0.7beta11-14 DLLNUM 10007 2.1.0.7beta11-14 (binary compatible)
58 * 1.0.7beta15-18 1 10007 2.1.0.7beta15-18 (binary compatible)
59 * 1.0.7rc1-2 1 10007 2.1.0.7rc1-2 (binary compatible)
60 * 1.0.7 1 10007 (still compatible)
61 * 1.0.8beta1-4 1 10008 2.1.0.8beta1-4
62 * 1.0.8rc1 1 10008 2.1.0.8rc1
63 * 1.0.8 1 10008 2.1.0.8
64 * 1.0.9beta1-6 1 10009 2.1.0.9beta1-6
65 * 1.0.9rc1 1 10009 2.1.0.9rc1
66 * 1.0.9beta7-10 1 10009 2.1.0.9beta7-10
67 * 1.0.9rc2 1 10009 2.1.0.9rc2
68 * 1.0.9 1 10009 2.1.0.9
69 * 1.0.10beta1 1 10010 2.1.0.10beta1
70 * 1.0.10rc1 1 10010 2.1.0.10rc1
71 * 1.0.10 1 10010 2.1.0.10
72 * 1.0.11beta1-3 1 10011 2.1.0.11beta1-3
73 * 1.0.11rc1 1 10011 2.1.0.11rc1
74 * 1.0.11 1 10011 2.1.0.11
75 * 1.0.12beta1-2 2 10012 2.1.0.12beta1-2
76 * 1.0.12rc1 2 10012 2.1.0.12rc1
77 * 1.0.12 2 10012 2.1.0.12
78 * 1.1.0a-f - 10100 2.1.1.0a-f (branch abandoned)
79 * 1.2.0beta1-2 2 10200 2.1.2.0beta1-2
80 * 1.2.0beta3-5 3 10200 3.1.2.0beta3-5
81 * 1.2.0rc1 3 10200 3.1.2.0rc1
82 * 1.2.0 3 10200 3.1.2.0
83 * 1.2.1beta1-4 3 10201 3.1.2.1beta1-4
84 * 1.2.1rc1-2 3 10201 3.1.2.1rc1-2
85 * 1.2.1 3 10201 3.1.2.1
86 * 1.2.2beta1-6 12 10202 12.so.0.1.2.2beta1-6
87 * 1.0.13beta1 10 10013 10.so.0.1.0.13beta1
88 * 1.0.13rc1 10 10013 10.so.0.1.0.13rc1
89 * 1.2.2rc1 12 10202 12.so.0.1.2.2rc1
90 * 1.0.13 10 10013 10.so.0.1.0.13
91 * 1.2.2 12 10202 12.so.0.1.2.2
92 * 1.2.3rc1-6 12 10203 12.so.0.1.2.3rc1-6
93 * 1.2.3 12 10203 12.so.0.1.2.3
94 * 1.2.4beta1-3 13 10204 12.so.0.1.2.4beta1-3
95 * 1.0.14rc1 13 10014 10.so.0.1.0.14rc1
96 * 1.2.4rc1 13 10204 12.so.0.1.2.4rc1
97 * 1.0.14 10 10014 10.so.0.1.0.14
98 * 1.2.4 13 10204 12.so.0.1.2.4
99 * 1.2.5beta1-2 13 10205 12.so.0.1.2.5beta1-2
100 * 1.0.15rc1-3 10 10015 10.so.0.1.0.15rc1-3
101 * 1.2.5rc1-3 13 10205 12.so.0.1.2.5rc1-3
102 * 1.0.15 10 10015 10.so.0.1.0.15
103 * 1.2.5 13 10205 12.so.0.1.2.5
104 * 1.2.6beta1-4 13 10206 12.so.0.1.2.6beta1-4
105 * 1.0.16 10 10016 10.so.0.1.0.16
106 * 1.2.6 13 10206 12.so.0.1.2.6
107 * 1.2.7beta1-2 13 10207 12.so.0.1.2.7beta1-2
108 * 1.0.17rc1 10 10017 12.so.0.1.0.17rc1
109 * 1.2.7rc1 13 10207 12.so.0.1.2.7rc1
110 * 1.0.17 10 10017 12.so.0.1.0.17
111 * 1.2.7 13 10207 12.so.0.1.2.7
112 * 1.2.8beta1-5 13 10208 12.so.0.1.2.8beta1-5
113 * 1.0.18rc1-5 10 10018 12.so.0.1.0.18rc1-5
114 * 1.2.8rc1-5 13 10208 12.so.0.1.2.8rc1-5
115 * 1.0.18 10 10018 12.so.0.1.0.18
116 * 1.2.8 13 10208 12.so.0.1.2.8
117 * 1.2.9beta1-3 13 10209 12.so.0.1.2.9beta1-3
118 * 1.2.9beta4-11 13 10209 12.so.0.9[.0]
119 * 1.2.9rc1 13 10209 12.so.0.9[.0]
120 * 1.2.9 13 10209 12.so.0.9[.0]
121 * 1.2.10beta1-7 13 10210 12.so.0.10[.0]
122 * 1.2.10rc1-2 13 10210 12.so.0.10[.0]
123 * 1.2.10 13 10210 12.so.0.10[.0]
124 * 1.4.0beta1-5 14 10400 14.so.0.0[.0]
125 * 1.2.11beta1-4 13 10211 12.so.0.11[.0]
126 * 1.4.0beta7-8 14 10400 14.so.0.0[.0]
127 * 1.2.11 13 10211 12.so.0.11[.0]
128 * 1.2.12 13 10212 12.so.0.12[.0]
129 * 1.4.0beta9-14 14 10400 14.so.0.0[.0]
130 * 1.2.13 13 10213 12.so.0.13[.0]
131 * 1.4.0beta15-36 14 10400 14.so.0.0[.0]
132 * 1.4.0beta37-87 14 10400 14.so.14.0[.0]
133 * 1.4.0rc01 14 10400 14.so.14.0[.0]
134 * 1.4.0beta88-109 14 10400 14.so.14.0[.0]
135 * 1.4.0rc02-08 14 10400 14.so.14.0[.0]
136 * 1.4.0 14 10400 14.so.14.0[.0]
137 * 1.4.1beta01-03 14 10401 14.so.14.1[.0]
138 * 1.4.1rc01 14 10401 14.so.14.1[.0]
139 * 1.4.1beta04-12 14 10401 14.so.14.1[.0]
140 * 1.4.1 14 10401 14.so.14.1[.0]
141 * 1.4.2 14 10402 14.so.14.2[.0]
142 * 1.4.3 14 10403 14.so.14.3[.0]
143 * 1.4.4 14 10404 14.so.14.4[.0]
144 * 1.5.0beta01-58 15 10500 15.so.15.0[.0]
145 * 1.5.0rc01-07 15 10500 15.so.15.0[.0]
146 * 1.5.0 15 10500 15.so.15.0[.0]
147 * 1.5.1beta01-11 15 10501 15.so.15.1[.0]
148 * 1.5.1rc01-02 15 10501 15.so.15.1[.0]
149 * 1.5.1 15 10501 15.so.15.1[.0]
150 * 1.5.2beta01-03 15 10502 15.so.15.2[.0]
151 * 1.5.2rc01-03 15 10502 15.so.15.2[.0]
152 * 1.5.2 15 10502 15.so.15.2[.0]
153 * 1.5.3beta01-10 15 10503 15.so.15.3[.0]
154 * 1.5.3rc01-02 15 10503 15.so.15.3[.0]
155 * 1.5.3beta11 15 10503 15.so.15.3[.0]
157 * 1.5.4beta01-08 15 10504 15.so.15.4[.0]
158 * 1.5.4rc01 15 10504 15.so.15.4[.0]
159 * 1.5.4 15 10504 15.so.15.4[.0]
160 * 1.5.5beta01-08 15 10505 15.so.15.5[.0]
161 * 1.5.5rc01 15 10505 15.so.15.5[.0]
162 * 1.5.5 15 10505 15.so.15.5[.0]
163 * 1.5.6beta01-07 15 10506 15.so.15.6[.0]
164 * 1.5.6rc01-03 15 10506 15.so.15.6[.0]
165 * 1.5.6 15 10506 15.so.15.6[.0]
166 * 1.5.7beta01-05 15 10507 15.so.15.7[.0]
167 * 1.5.7rc01-03 15 10507 15.so.15.7[.0]
168 * 1.5.7 15 10507 15.so.15.7[.0]
169 * 1.6.0beta01-40 16 10600 16.so.16.0[.0]
170 * 1.6.0rc01-08 16 10600 16.so.16.0[.0]
171 * 1.6.0 16 10600 16.so.16.0[.0]
172 * 1.6.1beta01-09 16 10601 16.so.16.1[.0]
173 * 1.6.1rc01 16 10601 16.so.16.1[.0]
174 * 1.6.1 16 10601 16.so.16.1[.0]
175 * 1.6.2beta01 16 10602 16.so.16.2[.0]
176 * 1.6.2rc01-06 16 10602 16.so.16.2[.0]
177 * 1.6.2 16 10602 16.so.16.2[.0]
179 * Henceforth the source version will match the shared-library major
180 * and minor numbers; the shared-library major version number will be
181 * used for changes in backward compatibility, as it is intended. The
182 * PNG_LIBPNG_VER macro, which is not used within libpng but is available
183 * for applications, is an unsigned integer of the form xyyzz corresponding
184 * to the source version x.y.z (leading zeros in y and z). Beta versions
185 * were given the previous public release number plus a letter, until
186 * version 1.0.6j; from then on they were given the upcoming public
187 * release number plus "betaNN" or "rcNN".
189 * Binary incompatibility exists only when applications make direct access
190 * to the info_ptr or png_ptr members through png.h, and the compiled
191 * application is loaded with a different version of the library.
193 * DLLNUM will change each time there are forward or backward changes
194 * in binary compatibility (e.g., when a new feature is added).
196 * See libpng-manual.txt or libpng.3 for more information. The PNG
197 * specification is available as a W3C Recommendation and as an ISO
198 * Specification, <http://www.w3.org/TR/2003/REC-PNG-20031110/
202 * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
204 * If you modify libpng you may insert additional notices immediately following
207 * This code is released under the libpng license.
209 * libpng versions 1.2.6, August 15, 2004, through 1.6.2, April 25, 2013, are
210 * Copyright (c) 2004, 2006-2013 Glenn Randers-Pehrson, and are
211 * distributed according to the same disclaimer and license as libpng-1.2.5
212 * with the following individual added to the list of Contributing Authors:
216 * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
217 * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
218 * distributed according to the same disclaimer and license as libpng-1.0.6
219 * with the following individuals added to the list of Contributing Authors:
221 * Simon-Pierre Cadieux
225 * and with the following additions to the disclaimer:
227 * There is no warranty against interference with your enjoyment of the
228 * library or against infringement. There is no warranty that our
229 * efforts or the library will fulfill any of your particular purposes
230 * or needs. This library is provided with all faults, and the entire
231 * risk of satisfactory quality, performance, accuracy, and effort is with
234 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
235 * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson, and are
236 * distributed according to the same disclaimer and license as libpng-0.96,
237 * with the following individuals added to the list of Contributing Authors:
240 * Glenn Randers-Pehrson
243 * libpng versions 0.89, June 1996, through 0.96, May 1997, are
244 * Copyright (c) 1996, 1997 Andreas Dilger
245 * Distributed according to the same disclaimer and license as libpng-0.88,
246 * with the following individuals added to the list of Contributing Authors:
255 * libpng versions 0.5, May 1995, through 0.88, January 1996, are
256 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
258 * For the purposes of this copyright and license, "Contributing Authors"
259 * is defined as the following set of individuals:
267 * The PNG Reference Library is supplied "AS IS". The Contributing Authors
268 * and Group 42, Inc. disclaim all warranties, expressed or implied,
269 * including, without limitation, the warranties of merchantability and of
270 * fitness for any purpose. The Contributing Authors and Group 42, Inc.
271 * assume no liability for direct, indirect, incidental, special, exemplary,
272 * or consequential damages, which may result from the use of the PNG
273 * Reference Library, even if advised of the possibility of such damage.
275 * Permission is hereby granted to use, copy, modify, and distribute this
276 * source code, or portions hereof, for any purpose, without fee, subject
277 * to the following restrictions:
279 * 1. The origin of this source code must not be misrepresented.
281 * 2. Altered versions must be plainly marked as such and must not
282 * be misrepresented as being the original source.
284 * 3. This Copyright notice may not be removed or altered from
285 * any source or altered source distribution.
287 * The Contributing Authors and Group 42, Inc. specifically permit, without
288 * fee, and encourage the use of this source code as a component to
289 * supporting the PNG file format in commercial products. If you use this
290 * source code in a product, acknowledgment is not required but would be
295 * A "png_get_copyright" function is available, for convenient use in "about"
296 * boxes and the like:
298 * printf("%s", png_get_copyright(NULL));
300 * Also, the PNG logo (in PNG format, of course) is supplied in the
301 * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
305 * Libpng is OSI Certified Open Source Software. OSI Certified is a
306 * certification mark of the Open Source Initiative.
310 * The contributing authors would like to thank all those who helped
311 * with testing, bug fixes, and patience. This wouldn't have been
312 * possible without all of you.
314 * Thanks to Frank J. T. Wojcik for helping with the documentation.
318 * Y2K compliance in libpng:
319 * =========================
323 * Since the PNG Development group is an ad-hoc body, we can't make
324 * an official declaration.
326 * This is your unofficial assurance that libpng from version 0.71 and
327 * upward through 1.6.2 are Y2K compliant. It is my belief that
328 * earlier versions were also Y2K compliant.
330 * Libpng only has two year fields. One is a 2-byte unsigned integer
331 * that will hold years up to 65535. The other, which is deprecated,
332 * holds the date in text format, and will hold years up to 9999.
335 * "png_uint_16 year" in png_time_struct.
338 * "char time_buffer[29]" in png_struct. This is no longer used
339 * in libpng-1.6.x and will be removed from libpng-1.7.0.
341 * There are seven time-related functions:
342 * png.c: png_convert_to_rfc_1123_buffer() in png.c
343 * (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
344 * png_convert_to_rfc_1152() in error prior to libpng-0.98)
345 * png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
346 * png_convert_from_time_t() in pngwrite.c
347 * png_get_tIME() in pngget.c
348 * png_handle_tIME() in pngrutil.c, called in pngread.c
349 * png_set_tIME() in pngset.c
350 * png_write_tIME() in pngwutil.c, called in pngwrite.c
352 * All handle dates properly in a Y2K environment. The
353 * png_convert_from_time_t() function calls gmtime() to convert from system
354 * clock time, which returns (year - 1900), which we properly convert to
355 * the full 4-digit year. There is a possibility that libpng applications
356 * are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
357 * function, or that they are incorrectly passing only a 2-digit year
358 * instead of "year - 1900" into the png_convert_from_struct_tm() function,
359 * but this is not under our control. The libpng documentation has always
360 * stated that it works with 4-digit years, and the APIs have been
361 * documented as such.
363 * The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
364 * integer to hold the year, and can hold years as large as 65535.
366 * zlib, upon which libpng depends, is also Y2K compliant. It contains
367 * no date-related code.
369 * Glenn Randers-Pehrson
371 * PNG Development Group
377 /* This is not the place to learn how to use libpng. The file libpng-manual.txt
378 * describes how to use libpng, and the file example.c summarizes it
379 * with some code on which to build. This file is useful for looking
380 * at the actual function definitions and structure components.
382 * If you just need to read a PNG file and don't want to read the documentation
383 * skip to the end of this file and read the section entitled 'simplified API'.
386 /* Version information for png.h - this should match the version in png.c */
387 #define PNG_LIBPNG_VER_STRING "1.6.2"
388 #define PNG_HEADER_VERSION_STRING \
389 " libpng version 1.6.2 - April 25, 2013\n"
391 #define PNG_LIBPNG_VER_SONUM 16
392 #define PNG_LIBPNG_VER_DLLNUM 16
394 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
395 #define PNG_LIBPNG_VER_MAJOR 1
396 #define PNG_LIBPNG_VER_MINOR 6
397 #define PNG_LIBPNG_VER_RELEASE 2
399 /* This should match the numeric part of the final component of
400 * PNG_LIBPNG_VER_STRING, omitting any leading zero:
403 #define PNG_LIBPNG_VER_BUILD 0
406 #define PNG_LIBPNG_BUILD_ALPHA 1
407 #define PNG_LIBPNG_BUILD_BETA 2
408 #define PNG_LIBPNG_BUILD_RC 3
409 #define PNG_LIBPNG_BUILD_STABLE 4
410 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
412 /* Release-Specific Flags */
413 #define PNG_LIBPNG_BUILD_PATCH 8 /* Can be OR'ed with
414 PNG_LIBPNG_BUILD_STABLE only */
415 #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
416 PNG_LIBPNG_BUILD_SPECIAL */
417 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
418 PNG_LIBPNG_BUILD_PRIVATE */
420 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
422 /* Careful here. At one time, Guy wanted to use 082, but that would be octal.
423 * We must not include leading zeros.
424 * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
425 * version 1.0.0 was mis-numbered 100 instead of 10000). From
426 * version 1.0.1 it's xxyyzz, where x=major, y=minor, z=release
428 #define PNG_LIBPNG_VER 10602 /* 1.6.2 */
430 /* Library configuration: these options cannot be changed after
431 * the library has been built.
434 /* If pnglibconf.h is missing, you can
435 * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
437 # include "pnglibconf.h"
440 #ifndef PNG_VERSION_INFO_ONLY
441 /* Machine specific configuration. */
442 # include "pngconf.h"
446 * Added at libpng-1.2.8
448 * Ref MSDN: Private as priority over Special
449 * VS_FF_PRIVATEBUILD File *was not* built using standard release
450 * procedures. If this value is given, the StringFileInfo block must
451 * contain a PrivateBuild string.
453 * VS_FF_SPECIALBUILD File *was* built by the original company using
454 * standard release procedures but is a variation of the standard
455 * file of the same version number. If this value is given, the
456 * StringFileInfo block must contain a SpecialBuild string.
459 #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
460 # define PNG_LIBPNG_BUILD_TYPE \
461 (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
463 # ifdef PNG_LIBPNG_SPECIALBUILD
464 # define PNG_LIBPNG_BUILD_TYPE \
465 (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
467 # define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
471 #ifndef PNG_VERSION_INFO_ONLY
473 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
476 #endif /* __cplusplus */
478 /* Version information for C files, stored in png.c. This had better match
481 #define png_libpng_ver png_get_header_ver(NULL)
483 /* This file is arranged in several sections:
485 * 1. Any configuration options that can be specified by for the application
486 * code when it is built. (Build time configuration is in pnglibconf.h)
487 * 2. Type definitions (base types are defined in pngconf.h), structure
489 * 3. Exported library functions.
492 * The library source code has additional files (principally pngpriv.h) that
493 * allow configuration of the library.
495 /* Section 1: run time configuration
496 * See pnglibconf.h for build time configuration
498 * Run time configuration allows the application to choose between
499 * implementations of certain arithmetic APIs. The default is set
500 * at build time and recorded in pnglibconf.h, but it is safe to
501 * override these (and only these) settings. Note that this won't
502 * change what the library does, only application code, and the
503 * settings can (and probably should) be made on a per-file basis
504 * by setting the #defines before including png.h
506 * Use macros to read integers from PNG data or use the exported
508 * PNG_USE_READ_MACROS: use the macros (see below) Note that
509 * the macros evaluate their argument multiple times.
510 * PNG_NO_USE_READ_MACROS: call the relevant library function.
512 * Use the alternative algorithm for compositing alpha samples that
513 * does not use division?
514 * PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
516 * PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
518 * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
520 * PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
521 * APIs to png_warning.
522 * Otherwise the calls are mapped to png_error.
525 /* Section 2: type definitions, including structures and compile time
527 * See pngconf.h for base types that vary by machine/system
530 /* This triggers a compiler error in png.c, if png.c and png.h
531 * do not agree upon the version number.
533 typedef char* png_libpng_version_1_6_2
;
535 /* Basic control structions. Read libpng-manual.txt or libpng.3 for more info.
537 * png_struct is the cache of information used while reading or writing a single
538 * PNG file. One of these is always required, although the simplified API
539 * (below) hides the creation and destruction of it.
541 typedef struct png_struct_def png_struct
;
542 typedef const png_struct
* png_const_structp
;
543 typedef png_struct
* png_structp
;
544 typedef png_struct
* * png_structpp
;
546 /* png_info contains information read from or to be written to a PNG file. One
547 * or more of these must exist while reading or creating a PNG file. The
548 * information is not used by libpng during read but is used to control what
549 * gets written when a PNG file is created. "png_get_" function calls read
550 * information during read and "png_set_" functions calls write information
551 * when creating a PNG.
552 * been moved into a separate header file that is not accessible to
553 * applications. Read libpng-manual.txt or libpng.3 for more info.
555 typedef struct png_info_def png_info
;
556 typedef png_info
* png_infop
;
557 typedef const png_info
* png_const_infop
;
558 typedef png_info
* * png_infopp
;
560 /* Types with names ending 'p' are pointer types. The corresponding types with
561 * names ending 'rp' are identical pointer types except that the pointer is
562 * marked 'restrict', which means that it is the only pointer to the object
563 * passed to the function. Applications should not use the 'restrict' types;
564 * it is always valid to pass 'p' to a pointer with a function argument of the
565 * corresponding 'rp' type. Different compilers have different rules with
566 * regard to type matching in the presence of 'restrict'. For backward
567 * compatibility libpng callbacks never have 'restrict' in their parameters and,
568 * consequentially, writing portable application code is extremely difficult if
569 * an attempt is made to use 'restrict'.
571 typedef png_struct
* PNG_RESTRICT png_structrp
;
572 typedef const png_struct
* PNG_RESTRICT png_const_structrp
;
573 typedef png_info
* PNG_RESTRICT png_inforp
;
574 typedef const png_info
* PNG_RESTRICT png_const_inforp
;
576 /* Three color definitions. The order of the red, green, and blue, (and the
577 * exact size) is not important, although the size of the fields need to
578 * be png_byte or png_uint_16 (as defined below).
580 typedef struct png_color_struct
586 typedef png_color
* png_colorp
;
587 typedef const png_color
* png_const_colorp
;
588 typedef png_color
* * png_colorpp
;
590 typedef struct png_color_16_struct
592 png_byte index
; /* used for palette files */
593 png_uint_16 red
; /* for use in red green blue files */
596 png_uint_16 gray
; /* for use in grayscale files */
598 typedef png_color_16
* png_color_16p
;
599 typedef const png_color_16
* png_const_color_16p
;
600 typedef png_color_16
* * png_color_16pp
;
602 typedef struct png_color_8_struct
604 png_byte red
; /* for use in red green blue files */
607 png_byte gray
; /* for use in grayscale files */
608 png_byte alpha
; /* for alpha channel files */
610 typedef png_color_8
* png_color_8p
;
611 typedef const png_color_8
* png_const_color_8p
;
612 typedef png_color_8
* * png_color_8pp
;
615 * The following two structures are used for the in-core representation
618 typedef struct png_sPLT_entry_struct
624 png_uint_16 frequency
;
626 typedef png_sPLT_entry
* png_sPLT_entryp
;
627 typedef const png_sPLT_entry
* png_const_sPLT_entryp
;
628 typedef png_sPLT_entry
* * png_sPLT_entrypp
;
630 /* When the depth of the sPLT palette is 8 bits, the color and alpha samples
631 * occupy the LSB of their respective members, and the MSB of each member
632 * is zero-filled. The frequency member always occupies the full 16 bits.
635 typedef struct png_sPLT_struct
637 png_charp name
; /* palette name */
638 png_byte depth
; /* depth of palette samples */
639 png_sPLT_entryp entries
; /* palette entries */
640 png_int_32 nentries
; /* number of palette entries */
642 typedef png_sPLT_t
* png_sPLT_tp
;
643 typedef const png_sPLT_t
* png_const_sPLT_tp
;
644 typedef png_sPLT_t
* * png_sPLT_tpp
;
646 #ifdef PNG_TEXT_SUPPORTED
647 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
648 * and whether that contents is compressed or not. The "key" field
649 * points to a regular zero-terminated C string. The "text" fields can be a
650 * regular C string, an empty string, or a NULL pointer.
651 * However, the structure returned by png_get_text() will always contain
652 * the "text" field as a regular zero-terminated C string (possibly
653 * empty), never a NULL pointer, so it can be safely used in printf() and
654 * other string-handling functions. Note that the "itxt_length", "lang", and
655 * "lang_key" members of the structure only exist when the library is built
656 * with iTXt chunk support. Prior to libpng-1.4.0 the library was built by
657 * default without iTXt support. Also note that when iTXt *is* supported,
658 * the "lang" and "lang_key" fields contain NULL pointers when the
659 * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
660 * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
661 * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
662 * which is always 0 or 1, or its "compression method" which is always 0.
664 typedef struct png_text_struct
666 int compression
; /* compression value:
671 png_charp key
; /* keyword, 1-79 character description of "text" */
672 png_charp text
; /* comment, may be an empty string (ie "")
674 png_size_t text_length
; /* length of the text string */
675 png_size_t itxt_length
; /* length of the itxt string */
676 png_charp lang
; /* language code, 0-79 characters
678 png_charp lang_key
; /* keyword translated UTF-8 string, 0 or more
679 chars or a NULL pointer */
681 typedef png_text
* png_textp
;
682 typedef const png_text
* png_const_textp
;
683 typedef png_text
* * png_textpp
;
686 /* Supported compression types for text in PNG files (tEXt, and zTXt).
687 * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
688 #define PNG_TEXT_COMPRESSION_NONE_WR -3
689 #define PNG_TEXT_COMPRESSION_zTXt_WR -2
690 #define PNG_TEXT_COMPRESSION_NONE -1
691 #define PNG_TEXT_COMPRESSION_zTXt 0
692 #define PNG_ITXT_COMPRESSION_NONE 1
693 #define PNG_ITXT_COMPRESSION_zTXt 2
694 #define PNG_TEXT_COMPRESSION_LAST 3 /* Not a valid value */
696 /* png_time is a way to hold the time in an machine independent way.
697 * Two conversions are provided, both from time_t and struct tm. There
698 * is no portable way to convert to either of these structures, as far
699 * as I know. If you know of a portable way, send it to me. As a side
700 * note - PNG has always been Year 2000 compliant!
702 typedef struct png_time_struct
704 png_uint_16 year
; /* full year, as in, 1995 */
705 png_byte month
; /* month of year, 1 - 12 */
706 png_byte day
; /* day of month, 1 - 31 */
707 png_byte hour
; /* hour of day, 0 - 23 */
708 png_byte minute
; /* minute of hour, 0 - 59 */
709 png_byte second
; /* second of minute, 0 - 60 (for leap seconds) */
711 typedef png_time
* png_timep
;
712 typedef const png_time
* png_const_timep
;
713 typedef png_time
* * png_timepp
;
715 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
716 /* png_unknown_chunk is a structure to hold queued chunks for which there is
717 * no specific support. The idea is that we can use this to queue
718 * up private chunks for output even though the library doesn't actually
719 * know about their semantics.
721 * The data in the structure is set by libpng on read and used on write.
723 typedef struct png_unknown_chunk_t
725 png_byte name
[5]; /* Textual chunk name with '\0' terminator */
726 png_byte
*data
; /* Data, should not be modified on read! */
729 /* On write 'location' must be set using the flag values listed below.
730 * Notice that on read it is set by libpng however the values stored have
731 * more bits set than are listed below. Always treat the value as a
732 * bitmask. On write set only one bit - setting multiple bits may cause the
733 * chunk to be written in multiple places.
735 png_byte location
; /* mode of operation at read time */
739 typedef png_unknown_chunk
* png_unknown_chunkp
;
740 typedef const png_unknown_chunk
* png_const_unknown_chunkp
;
741 typedef png_unknown_chunk
* * png_unknown_chunkpp
;
744 /* Flag values for the unknown chunk location byte. */
745 #define PNG_HAVE_IHDR 0x01
746 #define PNG_HAVE_PLTE 0x02
747 #define PNG_AFTER_IDAT 0x08
749 /* Maximum positive integer used in PNG is (2^31)-1 */
750 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
751 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
752 #define PNG_SIZE_MAX ((png_size_t)(-1))
754 /* These are constants for fixed point values encoded in the
755 * PNG specification manner (x100000)
757 #define PNG_FP_1 100000
758 #define PNG_FP_HALF 50000
759 #define PNG_FP_MAX ((png_fixed_point)0x7fffffffL)
760 #define PNG_FP_MIN (-PNG_FP_MAX)
762 /* These describe the color_type field in png_info. */
763 /* color type masks */
764 #define PNG_COLOR_MASK_PALETTE 1
765 #define PNG_COLOR_MASK_COLOR 2
766 #define PNG_COLOR_MASK_ALPHA 4
768 /* color types. Note that not all combinations are legal */
769 #define PNG_COLOR_TYPE_GRAY 0
770 #define PNG_COLOR_TYPE_PALETTE (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
771 #define PNG_COLOR_TYPE_RGB (PNG_COLOR_MASK_COLOR)
772 #define PNG_COLOR_TYPE_RGB_ALPHA (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
773 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
775 #define PNG_COLOR_TYPE_RGBA PNG_COLOR_TYPE_RGB_ALPHA
776 #define PNG_COLOR_TYPE_GA PNG_COLOR_TYPE_GRAY_ALPHA
778 /* This is for compression type. PNG 1.0-1.2 only define the single type. */
779 #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
780 #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
782 /* This is for filter type. PNG 1.0-1.2 only define the single type. */
783 #define PNG_FILTER_TYPE_BASE 0 /* Single row per-byte filtering */
784 #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
785 #define PNG_FILTER_TYPE_DEFAULT PNG_FILTER_TYPE_BASE
787 /* These are for the interlacing type. These values should NOT be changed. */
788 #define PNG_INTERLACE_NONE 0 /* Non-interlaced image */
789 #define PNG_INTERLACE_ADAM7 1 /* Adam7 interlacing */
790 #define PNG_INTERLACE_LAST 2 /* Not a valid value */
792 /* These are for the oFFs chunk. These values should NOT be changed. */
793 #define PNG_OFFSET_PIXEL 0 /* Offset in pixels */
794 #define PNG_OFFSET_MICROMETER 1 /* Offset in micrometers (1/10^6 meter) */
795 #define PNG_OFFSET_LAST 2 /* Not a valid value */
797 /* These are for the pCAL chunk. These values should NOT be changed. */
798 #define PNG_EQUATION_LINEAR 0 /* Linear transformation */
799 #define PNG_EQUATION_BASE_E 1 /* Exponential base e transform */
800 #define PNG_EQUATION_ARBITRARY 2 /* Arbitrary base exponential transform */
801 #define PNG_EQUATION_HYPERBOLIC 3 /* Hyperbolic sine transformation */
802 #define PNG_EQUATION_LAST 4 /* Not a valid value */
804 /* These are for the sCAL chunk. These values should NOT be changed. */
805 #define PNG_SCALE_UNKNOWN 0 /* unknown unit (image scale) */
806 #define PNG_SCALE_METER 1 /* meters per pixel */
807 #define PNG_SCALE_RADIAN 2 /* radians per pixel */
808 #define PNG_SCALE_LAST 3 /* Not a valid value */
810 /* These are for the pHYs chunk. These values should NOT be changed. */
811 #define PNG_RESOLUTION_UNKNOWN 0 /* pixels/unknown unit (aspect ratio) */
812 #define PNG_RESOLUTION_METER 1 /* pixels/meter */
813 #define PNG_RESOLUTION_LAST 2 /* Not a valid value */
815 /* These are for the sRGB chunk. These values should NOT be changed. */
816 #define PNG_sRGB_INTENT_PERCEPTUAL 0
817 #define PNG_sRGB_INTENT_RELATIVE 1
818 #define PNG_sRGB_INTENT_SATURATION 2
819 #define PNG_sRGB_INTENT_ABSOLUTE 3
820 #define PNG_sRGB_INTENT_LAST 4 /* Not a valid value */
822 /* This is for text chunks */
823 #define PNG_KEYWORD_MAX_LENGTH 79
825 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
826 #define PNG_MAX_PALETTE_LENGTH 256
828 /* These determine if an ancillary chunk's data has been successfully read
829 * from the PNG header, or if the application has filled in the corresponding
830 * data in the info_struct to be written into the output file. The values
831 * of the PNG_INFO_<chunk> defines should NOT be changed.
833 #define PNG_INFO_gAMA 0x0001
834 #define PNG_INFO_sBIT 0x0002
835 #define PNG_INFO_cHRM 0x0004
836 #define PNG_INFO_PLTE 0x0008
837 #define PNG_INFO_tRNS 0x0010
838 #define PNG_INFO_bKGD 0x0020
839 #define PNG_INFO_hIST 0x0040
840 #define PNG_INFO_pHYs 0x0080
841 #define PNG_INFO_oFFs 0x0100
842 #define PNG_INFO_tIME 0x0200
843 #define PNG_INFO_pCAL 0x0400
844 #define PNG_INFO_sRGB 0x0800 /* GR-P, 0.96a */
845 #define PNG_INFO_iCCP 0x1000 /* ESR, 1.0.6 */
846 #define PNG_INFO_sPLT 0x2000 /* ESR, 1.0.6 */
847 #define PNG_INFO_sCAL 0x4000 /* ESR, 1.0.6 */
848 #define PNG_INFO_IDAT 0x8000 /* ESR, 1.0.6 */
850 /* This is used for the transformation routines, as some of them
851 * change these values for the row. It also should enable using
852 * the routines for other purposes.
854 typedef struct png_row_info_struct
856 png_uint_32 width
; /* width of row */
857 png_size_t rowbytes
; /* number of bytes in row */
858 png_byte color_type
; /* color type of row */
859 png_byte bit_depth
; /* bit depth of row */
860 png_byte channels
; /* number of channels (1, 2, 3, or 4) */
861 png_byte pixel_depth
; /* bits per pixel (depth * channels) */
864 typedef png_row_info
* png_row_infop
;
865 typedef png_row_info
* * png_row_infopp
;
867 /* These are the function types for the I/O functions and for the functions
868 * that allow the user to override the default I/O functions with his or her
869 * own. The png_error_ptr type should match that of user-supplied warning
870 * and error functions, while the png_rw_ptr type should match that of the
871 * user read/write data functions. Note that the 'write' function must not
872 * modify the buffer it is passed. The 'read' function, on the other hand, is
873 * expected to return the read data in the buffer.
875 typedef PNG_CALLBACK(void, *png_error_ptr
, (png_structp
, png_const_charp
));
876 typedef PNG_CALLBACK(void, *png_rw_ptr
, (png_structp
, png_bytep
, png_size_t
));
877 typedef PNG_CALLBACK(void, *png_flush_ptr
, (png_structp
));
878 typedef PNG_CALLBACK(void, *png_read_status_ptr
, (png_structp
, png_uint_32
,
880 typedef PNG_CALLBACK(void, *png_write_status_ptr
, (png_structp
, png_uint_32
,
883 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
884 typedef PNG_CALLBACK(void, *png_progressive_info_ptr
, (png_structp
, png_infop
));
885 typedef PNG_CALLBACK(void, *png_progressive_end_ptr
, (png_structp
, png_infop
));
887 /* The following callback receives png_uint_32 row_number, int pass for the
888 * png_bytep data of the row. When transforming an interlaced image the
889 * row number is the row number within the sub-image of the interlace pass, so
890 * the value will increase to the height of the sub-image (not the full image)
891 * then reset to 0 for the next pass.
893 * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
894 * find the output pixel (x,y) given an interlaced sub-image pixel
895 * (row,col,pass). (See below for these macros.)
897 typedef PNG_CALLBACK(void, *png_progressive_row_ptr
, (png_structp
, png_bytep
,
901 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
902 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
903 typedef PNG_CALLBACK(void, *png_user_transform_ptr
, (png_structp
, png_row_infop
,
907 #ifdef PNG_USER_CHUNKS_SUPPORTED
908 typedef PNG_CALLBACK(int, *png_user_chunk_ptr
, (png_structp
,
909 png_unknown_chunkp
));
911 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
912 /* not used anywhere */
913 /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
916 #ifdef PNG_SETJMP_SUPPORTED
917 /* This must match the function definition in <setjmp.h>, and the application
918 * must include this before png.h to obtain the definition of jmp_buf. The
919 * function is required to be PNG_NORETURN, but this is not checked. If the
920 * function does return the application will crash via an abort() or similar
923 * If you get a warning here while building the library you may need to make
924 * changes to ensure that pnglibconf.h records the calling convention used by
925 * your compiler. This may be very difficult - try using a different compiler
926 * to build the library!
928 PNG_FUNCTION(void, (PNGCAPI
*png_longjmp_ptr
), PNGARG((jmp_buf, int)), typedef);
931 /* Transform masks for the high-level interface */
932 #define PNG_TRANSFORM_IDENTITY 0x0000 /* read and write */
933 #define PNG_TRANSFORM_STRIP_16 0x0001 /* read only */
934 #define PNG_TRANSFORM_STRIP_ALPHA 0x0002 /* read only */
935 #define PNG_TRANSFORM_PACKING 0x0004 /* read and write */
936 #define PNG_TRANSFORM_PACKSWAP 0x0008 /* read and write */
937 #define PNG_TRANSFORM_EXPAND 0x0010 /* read only */
938 #define PNG_TRANSFORM_INVERT_MONO 0x0020 /* read and write */
939 #define PNG_TRANSFORM_SHIFT 0x0040 /* read and write */
940 #define PNG_TRANSFORM_BGR 0x0080 /* read and write */
941 #define PNG_TRANSFORM_SWAP_ALPHA 0x0100 /* read and write */
942 #define PNG_TRANSFORM_SWAP_ENDIAN 0x0200 /* read and write */
943 #define PNG_TRANSFORM_INVERT_ALPHA 0x0400 /* read and write */
944 #define PNG_TRANSFORM_STRIP_FILLER 0x0800 /* write only */
945 /* Added to libpng-1.2.34 */
946 #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
947 #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
948 /* Added to libpng-1.4.0 */
949 #define PNG_TRANSFORM_GRAY_TO_RGB 0x2000 /* read only */
950 /* Added to libpng-1.5.4 */
951 #define PNG_TRANSFORM_EXPAND_16 0x4000 /* read only */
952 #define PNG_TRANSFORM_SCALE_16 0x8000 /* read only */
954 /* Flags for MNG supported features */
955 #define PNG_FLAG_MNG_EMPTY_PLTE 0x01
956 #define PNG_FLAG_MNG_FILTER_64 0x04
957 #define PNG_ALL_MNG_FEATURES 0x05
959 /* NOTE: prior to 1.5 these functions had no 'API' style declaration,
960 * this allowed the zlib default functions to be used on Windows
961 * platforms. In 1.5 the zlib default malloc (which just calls malloc and
962 * ignores the first argument) should be completely compatible with the
965 typedef PNG_CALLBACK(png_voidp
, *png_malloc_ptr
, (png_structp
,
967 typedef PNG_CALLBACK(void, *png_free_ptr
, (png_structp
, png_voidp
));
969 /* Section 3: exported functions
970 * Here are the function definitions most commonly used. This is not
971 * the place to find out how to use libpng. See libpng-manual.txt for the
972 * full explanation, see example.c for the summary. This just provides
973 * a simple one line description of the use of each function.
975 * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
976 * pngconf.h and in the *.dfn files in the scripts directory.
978 * PNG_EXPORT(ordinal, type, name, (args));
980 * ordinal: ordinal that is used while building
981 * *.def files. The ordinal value is only
982 * relevant when preprocessing png.h with
983 * the *.dfn files for building symbol table
984 * entries, and are removed by pngconf.h.
985 * type: return type of the function
986 * name: function name
987 * args: function arguments, with types
989 * When we wish to append attributes to a function prototype we use
990 * the PNG_EXPORTA() macro instead.
992 * PNG_EXPORTA(ordinal, type, name, (args), attributes);
994 * ordinal, type, name, and args: same as in PNG_EXPORT().
995 * attributes: function attributes
998 /* Returns the version number of the library */
999 PNG_EXPORT(1, png_uint_32
, png_access_version_number
, (void));
1001 /* Tell lib we have already handled the first <num_bytes> magic bytes.
1002 * Handling more than 8 bytes from the beginning of the file is an error.
1004 PNG_EXPORT(2, void, png_set_sig_bytes
, (png_structrp png_ptr
, int num_bytes
));
1006 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
1007 * PNG file. Returns zero if the supplied bytes match the 8-byte PNG
1008 * signature, and non-zero otherwise. Having num_to_check == 0 or
1009 * start > 7 will always fail (ie return non-zero).
1011 PNG_EXPORT(3, int, png_sig_cmp
, (png_const_bytep sig
, png_size_t start
,
1012 png_size_t num_to_check
));
1014 /* Simple signature checking function. This is the same as calling
1015 * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
1017 #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
1019 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
1020 PNG_EXPORTA(4, png_structp
, png_create_read_struct
,
1021 (png_const_charp user_png_ver
, png_voidp error_ptr
,
1022 png_error_ptr error_fn
, png_error_ptr warn_fn
),
1025 /* Allocate and initialize png_ptr struct for writing, and any other memory */
1026 PNG_EXPORTA(5, png_structp
, png_create_write_struct
,
1027 (png_const_charp user_png_ver
, png_voidp error_ptr
, png_error_ptr error_fn
,
1028 png_error_ptr warn_fn
),
1031 PNG_EXPORT(6, png_size_t
, png_get_compression_buffer_size
,
1032 (png_const_structrp png_ptr
));
1034 PNG_EXPORT(7, void, png_set_compression_buffer_size
, (png_structrp png_ptr
,
1037 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
1040 #ifdef PNG_SETJMP_SUPPORTED
1041 /* This function returns the jmp_buf built in to *png_ptr. It must be
1042 * supplied with an appropriate 'longjmp' function to use on that jmp_buf
1043 * unless the default error function is overridden in which case NULL is
1044 * acceptable. The size of the jmp_buf is checked against the actual size
1045 * allocated by the library - the call will return NULL on a mismatch
1046 * indicating an ABI mismatch.
1048 PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn
, (png_structrp png_ptr
,
1049 png_longjmp_ptr longjmp_fn
, size_t jmp_buf_size
));
1050 # define png_jmpbuf(png_ptr) \
1051 (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
1053 # define png_jmpbuf(png_ptr) \
1054 (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
1056 /* This function should be used by libpng applications in place of
1057 * longjmp(png_ptr->jmpbuf, val). If longjmp_fn() has been set, it
1058 * will use it; otherwise it will call PNG_ABORT(). This function was
1059 * added in libpng-1.5.0.
1061 PNG_EXPORTA(9, void, png_longjmp
, (png_const_structrp png_ptr
, int val
),
1064 #ifdef PNG_READ_SUPPORTED
1065 /* Reset the compression stream */
1066 PNG_EXPORTA(10, int, png_reset_zstream
, (png_structrp png_ptr
), PNG_DEPRECATED
);
1069 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
1070 #ifdef PNG_USER_MEM_SUPPORTED
1071 PNG_EXPORTA(11, png_structp
, png_create_read_struct_2
,
1072 (png_const_charp user_png_ver
, png_voidp error_ptr
, png_error_ptr error_fn
,
1073 png_error_ptr warn_fn
,
1074 png_voidp mem_ptr
, png_malloc_ptr malloc_fn
, png_free_ptr free_fn
),
1076 PNG_EXPORTA(12, png_structp
, png_create_write_struct_2
,
1077 (png_const_charp user_png_ver
, png_voidp error_ptr
, png_error_ptr error_fn
,
1078 png_error_ptr warn_fn
,
1079 png_voidp mem_ptr
, png_malloc_ptr malloc_fn
, png_free_ptr free_fn
),
1083 /* Write the PNG file signature. */
1084 PNG_EXPORT(13, void, png_write_sig
, (png_structrp png_ptr
));
1086 /* Write a PNG chunk - size, type, (optional) data, CRC. */
1087 PNG_EXPORT(14, void, png_write_chunk
, (png_structrp png_ptr
, png_const_bytep
1088 chunk_name
, png_const_bytep data
, png_size_t length
));
1090 /* Write the start of a PNG chunk - length and chunk name. */
1091 PNG_EXPORT(15, void, png_write_chunk_start
, (png_structrp png_ptr
,
1092 png_const_bytep chunk_name
, png_uint_32 length
));
1094 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
1095 PNG_EXPORT(16, void, png_write_chunk_data
, (png_structrp png_ptr
,
1096 png_const_bytep data
, png_size_t length
));
1098 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
1099 PNG_EXPORT(17, void, png_write_chunk_end
, (png_structrp png_ptr
));
1101 /* Allocate and initialize the info structure */
1102 PNG_EXPORTA(18, png_infop
, png_create_info_struct
, (png_const_structrp png_ptr
),
1105 /* DEPRECATED: this function allowed init structures to be created using the
1106 * default allocation method (typically malloc). Use is deprecated in 1.6.0 and
1107 * the API will be removed in the future.
1109 PNG_EXPORTA(19, void, png_info_init_3
, (png_infopp info_ptr
,
1110 png_size_t png_info_struct_size
), PNG_DEPRECATED
);
1112 /* Writes all the PNG information before the image. */
1113 PNG_EXPORT(20, void, png_write_info_before_PLTE
,
1114 (png_structrp png_ptr
, png_const_inforp info_ptr
));
1115 PNG_EXPORT(21, void, png_write_info
,
1116 (png_structrp png_ptr
, png_const_inforp info_ptr
));
1118 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1119 /* Read the information before the actual image data. */
1120 PNG_EXPORT(22, void, png_read_info
,
1121 (png_structrp png_ptr
, png_inforp info_ptr
));
1124 #ifdef PNG_TIME_RFC1123_SUPPORTED
1125 /* Convert to a US string format: there is no localization support in this
1126 * routine. The original implementation used a 29 character buffer in
1127 * png_struct, this will be removed in future versions.
1129 #if PNG_LIBPNG_VER < 10700
1130 /* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
1131 PNG_EXPORTA(23, png_const_charp
, png_convert_to_rfc1123
, (png_structrp png_ptr
,
1132 png_const_timep ptime
),PNG_DEPRECATED
);
1134 PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer
, (char out
[29],
1135 png_const_timep ptime
));
1138 #ifdef PNG_CONVERT_tIME_SUPPORTED
1139 /* Convert from a struct tm to png_time */
1140 PNG_EXPORT(24, void, png_convert_from_struct_tm
, (png_timep ptime
,
1141 const struct tm
* ttime
));
1143 /* Convert from time_t to png_time. Uses gmtime() */
1144 PNG_EXPORT(25, void, png_convert_from_time_t
, (png_timep ptime
, time_t ttime
));
1145 #endif /* PNG_CONVERT_tIME_SUPPORTED */
1147 #ifdef PNG_READ_EXPAND_SUPPORTED
1148 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
1149 PNG_EXPORT(26, void, png_set_expand
, (png_structrp png_ptr
));
1150 PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8
, (png_structrp png_ptr
));
1151 PNG_EXPORT(28, void, png_set_palette_to_rgb
, (png_structrp png_ptr
));
1152 PNG_EXPORT(29, void, png_set_tRNS_to_alpha
, (png_structrp png_ptr
));
1155 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1156 /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
1157 * of a tRNS chunk if present.
1159 PNG_EXPORT(221, void, png_set_expand_16
, (png_structrp png_ptr
));
1162 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
1163 /* Use blue, green, red order for pixels. */
1164 PNG_EXPORT(30, void, png_set_bgr
, (png_structrp png_ptr
));
1167 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1168 /* Expand the grayscale to 24-bit RGB if necessary. */
1169 PNG_EXPORT(31, void, png_set_gray_to_rgb
, (png_structrp png_ptr
));
1172 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1173 /* Reduce RGB to grayscale. */
1174 #define PNG_ERROR_ACTION_NONE 1
1175 #define PNG_ERROR_ACTION_WARN 2
1176 #define PNG_ERROR_ACTION_ERROR 3
1177 #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
1179 PNG_FP_EXPORT(32, void, png_set_rgb_to_gray
, (png_structrp png_ptr
,
1180 int error_action
, double red
, double green
))
1181 PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed
, (png_structrp png_ptr
,
1182 int error_action
, png_fixed_point red
, png_fixed_point green
))
1184 PNG_EXPORT(34, png_byte
, png_get_rgb_to_gray_status
, (png_const_structrp
1188 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
1189 PNG_EXPORT(35, void, png_build_grayscale_palette
, (int bit_depth
,
1190 png_colorp palette
));
1193 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1194 /* How the alpha channel is interpreted - this affects how the color channels of
1195 * a PNG file are returned when an alpha channel, or tRNS chunk in a palette
1198 * This has no effect on the way pixels are written into a PNG output
1199 * datastream. The color samples in a PNG datastream are never premultiplied
1200 * with the alpha samples.
1202 * The default is to return data according to the PNG specification: the alpha
1203 * channel is a linear measure of the contribution of the pixel to the
1204 * corresponding composited pixel. The gamma encoded color channels must be
1205 * scaled according to the contribution and to do this it is necessary to undo
1206 * the encoding, scale the color values, perform the composition and reencode
1207 * the values. This is the 'PNG' mode.
1209 * The alternative is to 'associate' the alpha with the color information by
1210 * storing color channel values that have been scaled by the alpha. The
1211 * advantage is that the color channels can be resampled (the image can be
1212 * scaled) in this form. The disadvantage is that normal practice is to store
1213 * linear, not (gamma) encoded, values and this requires 16-bit channels for
1214 * still images rather than the 8-bit channels that are just about sufficient if
1215 * gamma encoding is used. In addition all non-transparent pixel values,
1216 * including completely opaque ones, must be gamma encoded to produce the final
1217 * image. This is the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' mode (the
1218 * latter being the two common names for associated alpha color channels.)
1220 * Since it is not necessary to perform arithmetic on opaque color values so
1221 * long as they are not to be resampled and are in the final color space it is
1222 * possible to optimize the handling of alpha by storing the opaque pixels in
1223 * the PNG format (adjusted for the output color space) while storing partially
1224 * opaque pixels in the standard, linear, format. The accuracy required for
1225 * standard alpha composition is relatively low, because the pixels are
1226 * isolated, therefore typically the accuracy loss in storing 8-bit linear
1227 * values is acceptable. (This is not true if the alpha channel is used to
1228 * simulate transparency over large areas - use 16 bits or the PNG mode in
1229 * this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
1230 * treated as opaque only if the alpha value is equal to the maximum value.
1232 * The final choice is to gamma encode the alpha channel as well. This is
1233 * broken because, in practice, no implementation that uses this choice
1234 * correctly undoes the encoding before handling alpha composition. Use this
1235 * choice only if other serious errors in the software or hardware you use
1236 * mandate it; the typical serious error is for dark halos to appear around
1237 * opaque areas of the composited PNG image because of arithmetic overflow.
1239 * The API function png_set_alpha_mode specifies which of these choices to use
1240 * with an enumerated 'mode' value and the gamma of the required output:
1242 #define PNG_ALPHA_PNG 0 /* according to the PNG standard */
1243 #define PNG_ALPHA_STANDARD 1 /* according to Porter/Duff */
1244 #define PNG_ALPHA_ASSOCIATED 1 /* as above; this is the normal practice */
1245 #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
1246 #define PNG_ALPHA_OPTIMIZED 2 /* 'PNG' for opaque pixels, else 'STANDARD' */
1247 #define PNG_ALPHA_BROKEN 3 /* the alpha channel is gamma encoded */
1249 PNG_FP_EXPORT(227, void, png_set_alpha_mode
, (png_structrp png_ptr
, int mode
,
1250 double output_gamma
))
1251 PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed
, (png_structrp png_ptr
,
1252 int mode
, png_fixed_point output_gamma
))
1255 #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1256 /* The output_gamma value is a screen gamma in libpng terminology: it expresses
1257 * how to decode the output values, not how they are encoded. The values used
1258 * correspond to the normal numbers used to describe the overall gamma of a
1259 * computer display system; for example 2.2 for an sRGB conformant system. The
1260 * values are scaled by 100000 in the _fixed version of the API (so 220000 for
1263 * The inverse of the value is always used to provide a default for the PNG file
1264 * encoding if it has no gAMA chunk and if png_set_gamma() has not been called
1265 * to override the PNG gamma information.
1267 * When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
1268 * opaque pixels however pixels with lower alpha values are not encoded,
1269 * regardless of the output gamma setting.
1271 * When the standard Porter Duff handling is requested with mode 1 the output
1272 * encoding is set to be linear and the output_gamma value is only relevant
1273 * as a default for input data that has no gamma information. The linear output
1274 * encoding will be overridden if png_set_gamma() is called - the results may be
1275 * highly unexpected!
1277 * The following numbers are derived from the sRGB standard and the research
1278 * behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
1279 * 0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
1280 * correction required to take account of any differences in the color
1281 * environment of the original scene and the intended display environment; the
1282 * value expresses how to *decode* the image for display, not how the original
1283 * data was *encoded*.
1285 * sRGB provides a peg for the PNG standard by defining a viewing environment.
1286 * sRGB itself, and earlier TV standards, actually use a more complex transform
1287 * (a linear portion then a gamma 2.4 power law) than PNG can express. (PNG is
1288 * limited to simple power laws.) By saying that an image for direct display on
1289 * an sRGB conformant system should be stored with a gAMA chunk value of 45455
1290 * (11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
1291 * makes it possible to derive values for other display systems and
1294 * The Mac value is deduced from the sRGB based on an assumption that the actual
1295 * extra viewing correction used in early Mac display systems was implemented as
1296 * a power 1.45 lookup table.
1298 * Any system where a programmable lookup table is used or where the behavior of
1299 * the final display device characteristics can be changed requires system
1300 * specific code to obtain the current characteristic. However this can be
1301 * difficult and most PNG gamma correction only requires an approximate value.
1303 * By default, if png_set_alpha_mode() is not called, libpng assumes that all
1304 * values are unencoded, linear, values and that the output device also has a
1305 * linear characteristic. This is only very rarely correct - it is invariably
1306 * better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
1307 * default if you don't know what the right answer is!
1309 * The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
1310 * 10.6) which used a correction table to implement a somewhat lower gamma on an
1311 * otherwise sRGB system.
1313 * Both these values are reserved (not simple gamma values) in order to allow
1314 * more precise correction internally in the future.
1316 * NOTE: the following values can be passed to either the fixed or floating
1317 * point APIs, but the floating point API will also accept floating point
1320 #define PNG_DEFAULT_sRGB -1 /* sRGB gamma and color space */
1321 #define PNG_GAMMA_MAC_18 -2 /* Old Mac '1.8' gamma and color space */
1322 #define PNG_GAMMA_sRGB 220000 /* Television standards--matches sRGB gamma */
1323 #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
1326 /* The following are examples of calls to png_set_alpha_mode to achieve the
1327 * required overall gamma correction and, where necessary, alpha
1328 * premultiplication.
1330 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1331 * This is the default libpng handling of the alpha channel - it is not
1332 * pre-multiplied into the color components. In addition the call states
1333 * that the output is for a sRGB system and causes all PNG files without gAMA
1334 * chunks to be assumed to be encoded using sRGB.
1336 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1337 * In this case the output is assumed to be something like an sRGB conformant
1338 * display preceeded by a power-law lookup table of power 1.45. This is how
1339 * early Mac systems behaved.
1341 * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
1342 * This is the classic Jim Blinn approach and will work in academic
1343 * environments where everything is done by the book. It has the shortcoming
1344 * of assuming that input PNG data with no gamma information is linear - this
1345 * is unlikely to be correct unless the PNG files where generated locally.
1346 * Most of the time the output precision will be so low as to show
1347 * significant banding in dark areas of the image.
1349 * png_set_expand_16(pp);
1350 * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
1351 * This is a somewhat more realistic Jim Blinn inspired approach. PNG files
1352 * are assumed to have the sRGB encoding if not marked with a gamma value and
1353 * the output is always 16 bits per component. This permits accurate scaling
1354 * and processing of the data. If you know that your input PNG files were
1355 * generated locally you might need to replace PNG_DEFAULT_sRGB with the
1356 * correct value for your system.
1358 * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
1359 * If you just need to composite the PNG image onto an existing background
1360 * and if you control the code that does this you can use the optimization
1361 * setting. In this case you just copy completely opaque pixels to the
1362 * output. For pixels that are not completely transparent (you just skip
1363 * those) you do the composition math using png_composite or png_composite_16
1364 * below then encode the resultant 8-bit or 16-bit values to match the output
1368 * If neither the PNG nor the standard linear encoding work for you because
1369 * of the software or hardware you use then you have a big problem. The PNG
1370 * case will probably result in halos around the image. The linear encoding
1371 * will probably result in a washed out, too bright, image (it's actually too
1372 * contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
1373 * substantially reduce the halos. Alternatively try:
1375 * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
1376 * This option will also reduce the halos, but there will be slight dark
1377 * halos round the opaque parts of the image where the background is light.
1378 * In the OPTIMIZED mode the halos will be light halos where the background
1379 * is dark. Take your pick - the halos are unavoidable unless you can get
1380 * your hardware/software fixed! (The OPTIMIZED approach is slightly
1383 * When the default gamma of PNG files doesn't match the output gamma.
1384 * If you have PNG files with no gamma information png_set_alpha_mode allows
1385 * you to provide a default gamma, but it also sets the ouput gamma to the
1386 * matching value. If you know your PNG files have a gamma that doesn't
1387 * match the output you can take advantage of the fact that
1388 * png_set_alpha_mode always sets the output gamma but only sets the PNG
1389 * default if it is not already set:
1391 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1392 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1393 * The first call sets both the default and the output gamma values, the
1394 * second call overrides the output gamma without changing the default. This
1395 * is easier than achieving the same effect with png_set_gamma. You must use
1396 * PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
1397 * fire if more than one call to png_set_alpha_mode and png_set_background is
1398 * made in the same read operation, however multiple calls with PNG_ALPHA_PNG
1402 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1403 PNG_EXPORT(36, void, png_set_strip_alpha
, (png_structrp png_ptr
));
1406 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
1407 defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
1408 PNG_EXPORT(37, void, png_set_swap_alpha
, (png_structrp png_ptr
));
1411 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
1412 defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
1413 PNG_EXPORT(38, void, png_set_invert_alpha
, (png_structrp png_ptr
));
1416 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
1417 /* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
1418 PNG_EXPORT(39, void, png_set_filler
, (png_structrp png_ptr
, png_uint_32 filler
,
1420 /* The values of the PNG_FILLER_ defines should NOT be changed */
1421 # define PNG_FILLER_BEFORE 0
1422 # define PNG_FILLER_AFTER 1
1423 /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
1424 PNG_EXPORT(40, void, png_set_add_alpha
, (png_structrp png_ptr
,
1425 png_uint_32 filler
, int flags
));
1426 #endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */
1428 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
1429 /* Swap bytes in 16-bit depth files. */
1430 PNG_EXPORT(41, void, png_set_swap
, (png_structrp png_ptr
));
1433 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
1434 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
1435 PNG_EXPORT(42, void, png_set_packing
, (png_structrp png_ptr
));
1438 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
1439 defined(PNG_WRITE_PACKSWAP_SUPPORTED)
1440 /* Swap packing order of pixels in bytes. */
1441 PNG_EXPORT(43, void, png_set_packswap
, (png_structrp png_ptr
));
1444 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
1445 /* Converts files to legal bit depths. */
1446 PNG_EXPORT(44, void, png_set_shift
, (png_structrp png_ptr
, png_const_color_8p
1450 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
1451 defined(PNG_WRITE_INTERLACING_SUPPORTED)
1452 /* Have the code handle the interlacing. Returns the number of passes.
1453 * MUST be called before png_read_update_info or png_start_read_image,
1454 * otherwise it will not have the desired effect. Note that it is still
1455 * necessary to call png_read_row or png_read_rows png_get_image_height
1456 * times for each pass.
1458 PNG_EXPORT(45, int, png_set_interlace_handling
, (png_structrp png_ptr
));
1461 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
1462 /* Invert monochrome files */
1463 PNG_EXPORT(46, void, png_set_invert_mono
, (png_structrp png_ptr
));
1466 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1467 /* Handle alpha and tRNS by replacing with a background color. Prior to
1468 * libpng-1.5.4 this API must not be called before the PNG file header has been
1469 * read. Doing so will result in unexpected behavior and possible warnings or
1470 * errors if the PNG file contains a bKGD chunk.
1472 PNG_FP_EXPORT(47, void, png_set_background
, (png_structrp png_ptr
,
1473 png_const_color_16p background_color
, int background_gamma_code
,
1474 int need_expand
, double background_gamma
))
1475 PNG_FIXED_EXPORT(215, void, png_set_background_fixed
, (png_structrp png_ptr
,
1476 png_const_color_16p background_color
, int background_gamma_code
,
1477 int need_expand
, png_fixed_point background_gamma
))
1479 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1480 # define PNG_BACKGROUND_GAMMA_UNKNOWN 0
1481 # define PNG_BACKGROUND_GAMMA_SCREEN 1
1482 # define PNG_BACKGROUND_GAMMA_FILE 2
1483 # define PNG_BACKGROUND_GAMMA_UNIQUE 3
1486 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1487 /* Scale a 16-bit depth file down to 8-bit, accurately. */
1488 PNG_EXPORT(229, void, png_set_scale_16
, (png_structrp png_ptr
));
1491 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1492 #define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
1493 /* Strip the second byte of information from a 16-bit depth file. */
1494 PNG_EXPORT(48, void, png_set_strip_16
, (png_structrp png_ptr
));
1497 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1498 /* Turn on quantizing, and reduce the palette to the number of colors
1501 PNG_EXPORT(49, void, png_set_quantize
, (png_structrp png_ptr
,
1502 png_colorp palette
, int num_palette
, int maximum_colors
,
1503 png_const_uint_16p histogram
, int full_quantize
));
1506 #ifdef PNG_READ_GAMMA_SUPPORTED
1507 /* The threshold on gamma processing is configurable but hard-wired into the
1508 * library. The following is the floating point variant.
1510 #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
1512 /* Handle gamma correction. Screen_gamma=(display_exponent).
1513 * NOTE: this API simply sets the screen and file gamma values. It will
1514 * therefore override the value for gamma in a PNG file if it is called after
1515 * the file header has been read - use with care - call before reading the PNG
1516 * file for best results!
1518 * These routines accept the same gamma values as png_set_alpha_mode (described
1519 * above). The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
1520 * API (floating point or fixed.) Notice, however, that the 'file_gamma' value
1521 * is the inverse of a 'screen gamma' value.
1523 PNG_FP_EXPORT(50, void, png_set_gamma
, (png_structrp png_ptr
,
1524 double screen_gamma
, double override_file_gamma
))
1525 PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed
, (png_structrp png_ptr
,
1526 png_fixed_point screen_gamma
, png_fixed_point override_file_gamma
))
1529 #ifdef PNG_WRITE_FLUSH_SUPPORTED
1530 /* Set how many lines between output flushes - 0 for no flushing */
1531 PNG_EXPORT(51, void, png_set_flush
, (png_structrp png_ptr
, int nrows
));
1532 /* Flush the current PNG output buffer */
1533 PNG_EXPORT(52, void, png_write_flush
, (png_structrp png_ptr
));
1536 /* Optional update palette with requested transformations */
1537 PNG_EXPORT(53, void, png_start_read_image
, (png_structrp png_ptr
));
1539 /* Optional call to update the users info structure */
1540 PNG_EXPORT(54, void, png_read_update_info
, (png_structrp png_ptr
,
1541 png_inforp info_ptr
));
1543 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1544 /* Read one or more rows of image data. */
1545 PNG_EXPORT(55, void, png_read_rows
, (png_structrp png_ptr
, png_bytepp row
,
1546 png_bytepp display_row
, png_uint_32 num_rows
));
1549 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1550 /* Read a row of data. */
1551 PNG_EXPORT(56, void, png_read_row
, (png_structrp png_ptr
, png_bytep row
,
1552 png_bytep display_row
));
1555 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1556 /* Read the whole image into memory at once. */
1557 PNG_EXPORT(57, void, png_read_image
, (png_structrp png_ptr
, png_bytepp image
));
1560 /* Write a row of image data */
1561 PNG_EXPORT(58, void, png_write_row
, (png_structrp png_ptr
,
1562 png_const_bytep row
));
1564 /* Write a few rows of image data: (*row) is not written; however, the type
1565 * is declared as writeable to maintain compatibility with previous versions
1566 * of libpng and to allow the 'display_row' array from read_rows to be passed
1567 * unchanged to write_rows.
1569 PNG_EXPORT(59, void, png_write_rows
, (png_structrp png_ptr
, png_bytepp row
,
1570 png_uint_32 num_rows
));
1572 /* Write the image data */
1573 PNG_EXPORT(60, void, png_write_image
, (png_structrp png_ptr
, png_bytepp image
));
1575 /* Write the end of the PNG file. */
1576 PNG_EXPORT(61, void, png_write_end
, (png_structrp png_ptr
,
1577 png_inforp info_ptr
));
1579 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1580 /* Read the end of the PNG file. */
1581 PNG_EXPORT(62, void, png_read_end
, (png_structrp png_ptr
, png_inforp info_ptr
));
1584 /* Free any memory associated with the png_info_struct */
1585 PNG_EXPORT(63, void, png_destroy_info_struct
, (png_const_structrp png_ptr
,
1586 png_infopp info_ptr_ptr
));
1588 /* Free any memory associated with the png_struct and the png_info_structs */
1589 PNG_EXPORT(64, void, png_destroy_read_struct
, (png_structpp png_ptr_ptr
,
1590 png_infopp info_ptr_ptr
, png_infopp end_info_ptr_ptr
));
1592 /* Free any memory associated with the png_struct and the png_info_structs */
1593 PNG_EXPORT(65, void, png_destroy_write_struct
, (png_structpp png_ptr_ptr
,
1594 png_infopp info_ptr_ptr
));
1596 /* Set the libpng method of handling chunk CRC errors */
1597 PNG_EXPORT(66, void, png_set_crc_action
, (png_structrp png_ptr
, int crit_action
,
1600 /* Values for png_set_crc_action() say how to handle CRC errors in
1601 * ancillary and critical chunks, and whether to use the data contained
1602 * therein. Note that it is impossible to "discard" data in a critical
1603 * chunk. For versions prior to 0.90, the action was always error/quit,
1604 * whereas in version 0.90 and later, the action for CRC errors in ancillary
1605 * chunks is warn/discard. These values should NOT be changed.
1607 * value action:critical action:ancillary
1609 #define PNG_CRC_DEFAULT 0 /* error/quit warn/discard data */
1610 #define PNG_CRC_ERROR_QUIT 1 /* error/quit error/quit */
1611 #define PNG_CRC_WARN_DISCARD 2 /* (INVALID) warn/discard data */
1612 #define PNG_CRC_WARN_USE 3 /* warn/use data warn/use data */
1613 #define PNG_CRC_QUIET_USE 4 /* quiet/use data quiet/use data */
1614 #define PNG_CRC_NO_CHANGE 5 /* use current value use current value */
1616 /* These functions give the user control over the scan-line filtering in
1617 * libpng and the compression methods used by zlib. These functions are
1618 * mainly useful for testing, as the defaults should work with most users.
1619 * Those users who are tight on memory or want faster performance at the
1620 * expense of compression can modify them. See the compression library
1621 * header file (zlib.h) for an explination of the compression functions.
1624 /* Set the filtering method(s) used by libpng. Currently, the only valid
1625 * value for "method" is 0.
1627 PNG_EXPORT(67, void, png_set_filter
, (png_structrp png_ptr
, int method
,
1630 /* Flags for png_set_filter() to say which filters to use. The flags
1631 * are chosen so that they don't conflict with real filter types
1632 * below, in case they are supplied instead of the #defined constants.
1633 * These values should NOT be changed.
1635 #define PNG_NO_FILTERS 0x00
1636 #define PNG_FILTER_NONE 0x08
1637 #define PNG_FILTER_SUB 0x10
1638 #define PNG_FILTER_UP 0x20
1639 #define PNG_FILTER_AVG 0x40
1640 #define PNG_FILTER_PAETH 0x80
1641 #define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
1642 PNG_FILTER_AVG | PNG_FILTER_PAETH)
1644 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
1645 * These defines should NOT be changed.
1647 #define PNG_FILTER_VALUE_NONE 0
1648 #define PNG_FILTER_VALUE_SUB 1
1649 #define PNG_FILTER_VALUE_UP 2
1650 #define PNG_FILTER_VALUE_AVG 3
1651 #define PNG_FILTER_VALUE_PAETH 4
1652 #define PNG_FILTER_VALUE_LAST 5
1654 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
1655 /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
1656 * defines, either the default (minimum-sum-of-absolute-differences), or
1657 * the experimental method (weighted-minimum-sum-of-absolute-differences).
1659 * Weights are factors >= 1.0, indicating how important it is to keep the
1660 * filter type consistent between rows. Larger numbers mean the current
1661 * filter is that many times as likely to be the same as the "num_weights"
1662 * previous filters. This is cumulative for each previous row with a weight.
1663 * There needs to be "num_weights" values in "filter_weights", or it can be
1664 * NULL if the weights aren't being specified. Weights have no influence on
1665 * the selection of the first row filter. Well chosen weights can (in theory)
1666 * improve the compression for a given image.
1668 * Costs are factors >= 1.0 indicating the relative decoding costs of a
1669 * filter type. Higher costs indicate more decoding expense, and are
1670 * therefore less likely to be selected over a filter with lower computational
1671 * costs. There needs to be a value in "filter_costs" for each valid filter
1672 * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
1673 * setting the costs. Costs try to improve the speed of decompression without
1674 * unduly increasing the compressed image size.
1676 * A negative weight or cost indicates the default value is to be used, and
1677 * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
1678 * The default values for both weights and costs are currently 1.0, but may
1679 * change if good general weighting/cost heuristics can be found. If both
1680 * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
1681 * to the UNWEIGHTED method, but with added encoding time/computation.
1683 PNG_FP_EXPORT(68, void, png_set_filter_heuristics
, (png_structrp png_ptr
,
1684 int heuristic_method
, int num_weights
, png_const_doublep filter_weights
,
1685 png_const_doublep filter_costs
))
1686 PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed
,
1687 (png_structrp png_ptr
, int heuristic_method
, int num_weights
,
1688 png_const_fixed_point_p filter_weights
,
1689 png_const_fixed_point_p filter_costs
))
1690 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
1692 /* Heuristic used for row filter selection. These defines should NOT be
1695 #define PNG_FILTER_HEURISTIC_DEFAULT 0 /* Currently "UNWEIGHTED" */
1696 #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 /* Used by libpng < 0.95 */
1697 #define PNG_FILTER_HEURISTIC_WEIGHTED 2 /* Experimental feature */
1698 #define PNG_FILTER_HEURISTIC_LAST 3 /* Not a valid value */
1700 #ifdef PNG_WRITE_SUPPORTED
1701 /* Set the library compression level. Currently, valid values range from
1702 * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
1703 * (0 - no compression, 9 - "maximal" compression). Note that tests have
1704 * shown that zlib compression levels 3-6 usually perform as well as level 9
1705 * for PNG images, and do considerably fewer caclulations. In the future,
1706 * these values may not correspond directly to the zlib compression levels.
1708 PNG_EXPORT(69, void, png_set_compression_level
, (png_structrp png_ptr
,
1711 PNG_EXPORT(70, void, png_set_compression_mem_level
, (png_structrp png_ptr
,
1714 PNG_EXPORT(71, void, png_set_compression_strategy
, (png_structrp png_ptr
,
1717 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1718 * smaller value of window_bits if it can do so safely.
1720 PNG_EXPORT(72, void, png_set_compression_window_bits
, (png_structrp png_ptr
,
1723 PNG_EXPORT(73, void, png_set_compression_method
, (png_structrp png_ptr
,
1727 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1728 /* Also set zlib parameters for compressing non-IDAT chunks */
1729 PNG_EXPORT(222, void, png_set_text_compression_level
, (png_structrp png_ptr
,
1732 PNG_EXPORT(223, void, png_set_text_compression_mem_level
, (png_structrp png_ptr
,
1735 PNG_EXPORT(224, void, png_set_text_compression_strategy
, (png_structrp png_ptr
,
1738 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1739 * smaller value of window_bits if it can do so safely.
1741 PNG_EXPORT(225, void, png_set_text_compression_window_bits
,
1742 (png_structrp png_ptr
, int window_bits
));
1744 PNG_EXPORT(226, void, png_set_text_compression_method
, (png_structrp png_ptr
,
1746 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
1748 /* These next functions are called for input/output, memory, and error
1749 * handling. They are in the file pngrio.c, pngwio.c, and pngerror.c,
1750 * and call standard C I/O routines such as fread(), fwrite(), and
1751 * fprintf(). These functions can be made to use other I/O routines
1752 * at run time for those applications that need to handle I/O in a
1753 * different manner by calling png_set_???_fn(). See libpng-manual.txt for
1757 #ifdef PNG_STDIO_SUPPORTED
1758 /* Initialize the input/output for the PNG file to the default functions. */
1759 PNG_EXPORT(74, void, png_init_io
, (png_structrp png_ptr
, png_FILE_p fp
));
1762 /* Replace the (error and abort), and warning functions with user
1763 * supplied functions. If no messages are to be printed you must still
1764 * write and use replacement functions. The replacement error_fn should
1765 * still do a longjmp to the last setjmp location if you are using this
1766 * method of error handling. If error_fn or warning_fn is NULL, the
1767 * default function will be used.
1770 PNG_EXPORT(75, void, png_set_error_fn
, (png_structrp png_ptr
,
1771 png_voidp error_ptr
, png_error_ptr error_fn
, png_error_ptr warning_fn
));
1773 /* Return the user pointer associated with the error functions */
1774 PNG_EXPORT(76, png_voidp
, png_get_error_ptr
, (png_const_structrp png_ptr
));
1776 /* Replace the default data output functions with a user supplied one(s).
1777 * If buffered output is not used, then output_flush_fn can be set to NULL.
1778 * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
1779 * output_flush_fn will be ignored (and thus can be NULL).
1780 * It is probably a mistake to use NULL for output_flush_fn if
1781 * write_data_fn is not also NULL unless you have built libpng with
1782 * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
1783 * default flush function, which uses the standard *FILE structure, will
1786 PNG_EXPORT(77, void, png_set_write_fn
, (png_structrp png_ptr
, png_voidp io_ptr
,
1787 png_rw_ptr write_data_fn
, png_flush_ptr output_flush_fn
));
1789 /* Replace the default data input function with a user supplied one. */
1790 PNG_EXPORT(78, void, png_set_read_fn
, (png_structrp png_ptr
, png_voidp io_ptr
,
1791 png_rw_ptr read_data_fn
));
1793 /* Return the user pointer associated with the I/O functions */
1794 PNG_EXPORT(79, png_voidp
, png_get_io_ptr
, (png_const_structrp png_ptr
));
1796 PNG_EXPORT(80, void, png_set_read_status_fn
, (png_structrp png_ptr
,
1797 png_read_status_ptr read_row_fn
));
1799 PNG_EXPORT(81, void, png_set_write_status_fn
, (png_structrp png_ptr
,
1800 png_write_status_ptr write_row_fn
));
1802 #ifdef PNG_USER_MEM_SUPPORTED
1803 /* Replace the default memory allocation functions with user supplied one(s). */
1804 PNG_EXPORT(82, void, png_set_mem_fn
, (png_structrp png_ptr
, png_voidp mem_ptr
,
1805 png_malloc_ptr malloc_fn
, png_free_ptr free_fn
));
1806 /* Return the user pointer associated with the memory functions */
1807 PNG_EXPORT(83, png_voidp
, png_get_mem_ptr
, (png_const_structrp png_ptr
));
1810 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1811 PNG_EXPORT(84, void, png_set_read_user_transform_fn
, (png_structrp png_ptr
,
1812 png_user_transform_ptr read_user_transform_fn
));
1815 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1816 PNG_EXPORT(85, void, png_set_write_user_transform_fn
, (png_structrp png_ptr
,
1817 png_user_transform_ptr write_user_transform_fn
));
1820 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
1821 PNG_EXPORT(86, void, png_set_user_transform_info
, (png_structrp png_ptr
,
1822 png_voidp user_transform_ptr
, int user_transform_depth
,
1823 int user_transform_channels
));
1824 /* Return the user pointer associated with the user transform functions */
1825 PNG_EXPORT(87, png_voidp
, png_get_user_transform_ptr
,
1826 (png_const_structrp png_ptr
));
1829 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
1830 /* Return information about the row currently being processed. Note that these
1831 * APIs do not fail but will return unexpected results if called outside a user
1832 * transform callback. Also note that when transforming an interlaced image the
1833 * row number is the row number within the sub-image of the interlace pass, so
1834 * the value will increase to the height of the sub-image (not the full image)
1835 * then reset to 0 for the next pass.
1837 * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
1838 * find the output pixel (x,y) given an interlaced sub-image pixel
1839 * (row,col,pass). (See below for these macros.)
1841 PNG_EXPORT(217, png_uint_32
, png_get_current_row_number
, (png_const_structrp
));
1842 PNG_EXPORT(218, png_byte
, png_get_current_pass_number
, (png_const_structrp
));
1845 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1846 /* This callback is called only for *unknown* chunks. If
1847 * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
1848 * chunks to be treated as unknown, however in this case the callback must do
1849 * any processing required by the chunk (e.g. by calling the appropriate
1852 * There is no write support - on write, by default, all the chunks in the
1853 * 'unknown' list are written in the specified position.
1855 * The integer return from the callback function is interpreted thus:
1857 * negative: An error occured, png_chunk_error will be called.
1858 * zero: The chunk was not handled, the chunk will be saved. A critical
1859 * chunk will cause an error at this point unless it is to be saved.
1860 * positive: The chunk was handled, libpng will ignore/discard it.
1862 * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
1863 * how this behavior will change in libpng 1.7
1865 PNG_EXPORT(88, void, png_set_read_user_chunk_fn
, (png_structrp png_ptr
,
1866 png_voidp user_chunk_ptr
, png_user_chunk_ptr read_user_chunk_fn
));
1869 #ifdef PNG_USER_CHUNKS_SUPPORTED
1870 PNG_EXPORT(89, png_voidp
, png_get_user_chunk_ptr
, (png_const_structrp png_ptr
));
1873 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1874 /* Sets the function callbacks for the push reader, and a pointer to a
1875 * user-defined structure available to the callback functions.
1877 PNG_EXPORT(90, void, png_set_progressive_read_fn
, (png_structrp png_ptr
,
1878 png_voidp progressive_ptr
, png_progressive_info_ptr info_fn
,
1879 png_progressive_row_ptr row_fn
, png_progressive_end_ptr end_fn
));
1881 /* Returns the user pointer associated with the push read functions */
1882 PNG_EXPORT(91, png_voidp
, png_get_progressive_ptr
,
1883 (png_const_structrp png_ptr
));
1885 /* Function to be called when data becomes available */
1886 PNG_EXPORT(92, void, png_process_data
, (png_structrp png_ptr
,
1887 png_inforp info_ptr
, png_bytep buffer
, png_size_t buffer_size
));
1889 /* A function which may be called *only* within png_process_data to stop the
1890 * processing of any more data. The function returns the number of bytes
1891 * remaining, excluding any that libpng has cached internally. A subsequent
1892 * call to png_process_data must supply these bytes again. If the argument
1893 * 'save' is set to true the routine will first save all the pending data and
1894 * will always return 0.
1896 PNG_EXPORT(219, png_size_t
, png_process_data_pause
, (png_structrp
, int save
));
1898 /* A function which may be called *only* outside (after) a call to
1899 * png_process_data. It returns the number of bytes of data to skip in the
1900 * input. Normally it will return 0, but if it returns a non-zero value the
1901 * application must skip than number of bytes of input data and pass the
1902 * following data to the next call to png_process_data.
1904 PNG_EXPORT(220, png_uint_32
, png_process_data_skip
, (png_structrp
));
1906 #ifdef PNG_READ_INTERLACING_SUPPORTED
1907 /* Function that combines rows. 'new_row' is a flag that should come from
1908 * the callback and be non-NULL if anything needs to be done; the library
1909 * stores its own version of the new data internally and ignores the passed
1912 PNG_EXPORT(93, void, png_progressive_combine_row
, (png_const_structrp png_ptr
,
1913 png_bytep old_row
, png_const_bytep new_row
));
1914 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1915 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1917 PNG_EXPORTA(94, png_voidp
, png_malloc
, (png_const_structrp png_ptr
,
1918 png_alloc_size_t size
), PNG_ALLOCATED
);
1919 /* Added at libpng version 1.4.0 */
1920 PNG_EXPORTA(95, png_voidp
, png_calloc
, (png_const_structrp png_ptr
,
1921 png_alloc_size_t size
), PNG_ALLOCATED
);
1923 /* Added at libpng version 1.2.4 */
1924 PNG_EXPORTA(96, png_voidp
, png_malloc_warn
, (png_const_structrp png_ptr
,
1925 png_alloc_size_t size
), PNG_ALLOCATED
);
1927 /* Frees a pointer allocated by png_malloc() */
1928 PNG_EXPORT(97, void, png_free
, (png_const_structrp png_ptr
, png_voidp ptr
));
1930 /* Free data that was allocated internally */
1931 PNG_EXPORT(98, void, png_free_data
, (png_const_structrp png_ptr
,
1932 png_inforp info_ptr
, png_uint_32 free_me
, int num
));
1934 /* Reassign responsibility for freeing existing data, whether allocated
1935 * by libpng or by the application; this works on the png_info structure passed
1936 * in, it does not change the state for other png_info structures.
1938 * It is unlikely that this function works correctly as of 1.6.0 and using it
1939 * may result either in memory leaks or double free of allocated data.
1941 PNG_EXPORTA(99, void, png_data_freer
, (png_const_structrp png_ptr
,
1942 png_inforp info_ptr
, int freer
, png_uint_32 mask
), PNG_DEPRECATED
);
1944 /* Assignments for png_data_freer */
1945 #define PNG_DESTROY_WILL_FREE_DATA 1
1946 #define PNG_SET_WILL_FREE_DATA 1
1947 #define PNG_USER_WILL_FREE_DATA 2
1948 /* Flags for png_ptr->free_me and info_ptr->free_me */
1949 #define PNG_FREE_HIST 0x0008
1950 #define PNG_FREE_ICCP 0x0010
1951 #define PNG_FREE_SPLT 0x0020
1952 #define PNG_FREE_ROWS 0x0040
1953 #define PNG_FREE_PCAL 0x0080
1954 #define PNG_FREE_SCAL 0x0100
1955 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
1956 # define PNG_FREE_UNKN 0x0200
1958 /* PNG_FREE_LIST 0x0400 removed in 1.6.0 because it is ignored */
1959 #define PNG_FREE_PLTE 0x1000
1960 #define PNG_FREE_TRNS 0x2000
1961 #define PNG_FREE_TEXT 0x4000
1962 #define PNG_FREE_ALL 0x7fff
1963 #define PNG_FREE_MUL 0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
1965 #ifdef PNG_USER_MEM_SUPPORTED
1966 PNG_EXPORTA(100, png_voidp
, png_malloc_default
, (png_const_structrp png_ptr
,
1967 png_alloc_size_t size
), PNG_ALLOCATED PNG_DEPRECATED
);
1968 PNG_EXPORTA(101, void, png_free_default
, (png_const_structrp png_ptr
,
1969 png_voidp ptr
), PNG_DEPRECATED
);
1972 #ifdef PNG_ERROR_TEXT_SUPPORTED
1973 /* Fatal error in PNG image of libpng - can't continue */
1974 PNG_EXPORTA(102, void, png_error
, (png_const_structrp png_ptr
,
1975 png_const_charp error_message
), PNG_NORETURN
);
1977 /* The same, but the chunk name is prepended to the error string. */
1978 PNG_EXPORTA(103, void, png_chunk_error
, (png_const_structrp png_ptr
,
1979 png_const_charp error_message
), PNG_NORETURN
);
1982 /* Fatal error in PNG image of libpng - can't continue */
1983 PNG_EXPORTA(104, void, png_err
, (png_const_structrp png_ptr
), PNG_NORETURN
);
1986 #ifdef PNG_WARNINGS_SUPPORTED
1987 /* Non-fatal error in libpng. Can continue, but may have a problem. */
1988 PNG_EXPORT(105, void, png_warning
, (png_const_structrp png_ptr
,
1989 png_const_charp warning_message
));
1991 /* Non-fatal error in libpng, chunk name is prepended to message. */
1992 PNG_EXPORT(106, void, png_chunk_warning
, (png_const_structrp png_ptr
,
1993 png_const_charp warning_message
));
1996 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1997 /* Benign error in libpng. Can continue, but may have a problem.
1998 * User can choose whether to handle as a fatal error or as a warning. */
1999 PNG_EXPORT(107, void, png_benign_error
, (png_const_structrp png_ptr
,
2000 png_const_charp warning_message
));
2002 #ifdef PNG_READ_SUPPORTED
2003 /* Same, chunk name is prepended to message (only during read) */
2004 PNG_EXPORT(108, void, png_chunk_benign_error
, (png_const_structrp png_ptr
,
2005 png_const_charp warning_message
));
2008 PNG_EXPORT(109, void, png_set_benign_errors
,
2009 (png_structrp png_ptr
, int allowed
));
2011 # ifdef PNG_ALLOW_BENIGN_ERRORS
2012 # define png_benign_error png_warning
2013 # define png_chunk_benign_error png_chunk_warning
2015 # define png_benign_error png_error
2016 # define png_chunk_benign_error png_chunk_error
2020 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
2021 * Similarly, the png_get_<chunk> calls are used to read values from the
2022 * png_info_struct, either storing the parameters in the passed variables, or
2023 * setting pointers into the png_info_struct where the data is stored. The
2024 * png_get_<chunk> functions return a non-zero value if the data was available
2025 * in info_ptr, or return zero and do not change any of the parameters if the
2026 * data was not available.
2028 * These functions should be used instead of directly accessing png_info
2029 * to avoid problems with future changes in the size and internal layout of
2032 /* Returns "flag" if chunk data is valid in info_ptr. */
2033 PNG_EXPORT(110, png_uint_32
, png_get_valid
, (png_const_structrp png_ptr
,
2034 png_const_inforp info_ptr
, png_uint_32 flag
));
2036 /* Returns number of bytes needed to hold a transformed row. */
2037 PNG_EXPORT(111, png_size_t
, png_get_rowbytes
, (png_const_structrp png_ptr
,
2038 png_const_inforp info_ptr
));
2040 #ifdef PNG_INFO_IMAGE_SUPPORTED
2041 /* Returns row_pointers, which is an array of pointers to scanlines that was
2042 * returned from png_read_png().
2044 PNG_EXPORT(112, png_bytepp
, png_get_rows
, (png_const_structrp png_ptr
,
2045 png_const_inforp info_ptr
));
2047 /* Set row_pointers, which is an array of pointers to scanlines for use
2048 * by png_write_png().
2050 PNG_EXPORT(113, void, png_set_rows
, (png_const_structrp png_ptr
,
2051 png_inforp info_ptr
, png_bytepp row_pointers
));
2054 /* Returns number of color channels in image. */
2055 PNG_EXPORT(114, png_byte
, png_get_channels
, (png_const_structrp png_ptr
,
2056 png_const_inforp info_ptr
));
2058 #ifdef PNG_EASY_ACCESS_SUPPORTED
2059 /* Returns image width in pixels. */
2060 PNG_EXPORT(115, png_uint_32
, png_get_image_width
, (png_const_structrp png_ptr
,
2061 png_const_inforp info_ptr
));
2063 /* Returns image height in pixels. */
2064 PNG_EXPORT(116, png_uint_32
, png_get_image_height
, (png_const_structrp png_ptr
,
2065 png_const_inforp info_ptr
));
2067 /* Returns image bit_depth. */
2068 PNG_EXPORT(117, png_byte
, png_get_bit_depth
, (png_const_structrp png_ptr
,
2069 png_const_inforp info_ptr
));
2071 /* Returns image color_type. */
2072 PNG_EXPORT(118, png_byte
, png_get_color_type
, (png_const_structrp png_ptr
,
2073 png_const_inforp info_ptr
));
2075 /* Returns image filter_type. */
2076 PNG_EXPORT(119, png_byte
, png_get_filter_type
, (png_const_structrp png_ptr
,
2077 png_const_inforp info_ptr
));
2079 /* Returns image interlace_type. */
2080 PNG_EXPORT(120, png_byte
, png_get_interlace_type
, (png_const_structrp png_ptr
,
2081 png_const_inforp info_ptr
));
2083 /* Returns image compression_type. */
2084 PNG_EXPORT(121, png_byte
, png_get_compression_type
, (png_const_structrp png_ptr
,
2085 png_const_inforp info_ptr
));
2087 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
2088 PNG_EXPORT(122, png_uint_32
, png_get_pixels_per_meter
,
2089 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2090 PNG_EXPORT(123, png_uint_32
, png_get_x_pixels_per_meter
,
2091 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2092 PNG_EXPORT(124, png_uint_32
, png_get_y_pixels_per_meter
,
2093 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2095 /* Returns pixel aspect ratio, computed from pHYs chunk data. */
2096 PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio
,
2097 (png_const_structrp png_ptr
, png_const_inforp info_ptr
))
2098 PNG_FIXED_EXPORT(210, png_fixed_point
, png_get_pixel_aspect_ratio_fixed
,
2099 (png_const_structrp png_ptr
, png_const_inforp info_ptr
))
2101 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
2102 PNG_EXPORT(126, png_int_32
, png_get_x_offset_pixels
,
2103 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2104 PNG_EXPORT(127, png_int_32
, png_get_y_offset_pixels
,
2105 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2106 PNG_EXPORT(128, png_int_32
, png_get_x_offset_microns
,
2107 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2108 PNG_EXPORT(129, png_int_32
, png_get_y_offset_microns
,
2109 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2111 #endif /* PNG_EASY_ACCESS_SUPPORTED */
2113 #ifdef PNG_READ_SUPPORTED
2114 /* Returns pointer to signature string read from PNG header */
2115 PNG_EXPORT(130, png_const_bytep
, png_get_signature
, (png_const_structrp png_ptr
,
2116 png_const_inforp info_ptr
));
2119 #ifdef PNG_bKGD_SUPPORTED
2120 PNG_EXPORT(131, png_uint_32
, png_get_bKGD
, (png_const_structrp png_ptr
,
2121 png_inforp info_ptr
, png_color_16p
*background
));
2124 #ifdef PNG_bKGD_SUPPORTED
2125 PNG_EXPORT(132, void, png_set_bKGD
, (png_const_structrp png_ptr
,
2126 png_inforp info_ptr
, png_const_color_16p background
));
2129 #ifdef PNG_cHRM_SUPPORTED
2130 PNG_FP_EXPORT(133, png_uint_32
, png_get_cHRM
, (png_const_structrp png_ptr
,
2131 png_const_inforp info_ptr
, double *white_x
, double *white_y
, double *red_x
,
2132 double *red_y
, double *green_x
, double *green_y
, double *blue_x
,
2134 PNG_FP_EXPORT(230, png_uint_32
, png_get_cHRM_XYZ
, (png_const_structrp png_ptr
,
2135 png_const_inforp info_ptr
, double *red_X
, double *red_Y
, double *red_Z
,
2136 double *green_X
, double *green_Y
, double *green_Z
, double *blue_X
,
2137 double *blue_Y
, double *blue_Z
))
2138 PNG_FIXED_EXPORT(134, png_uint_32
, png_get_cHRM_fixed
,
2139 (png_const_structrp png_ptr
, png_const_inforp info_ptr
,
2140 png_fixed_point
*int_white_x
, png_fixed_point
*int_white_y
,
2141 png_fixed_point
*int_red_x
, png_fixed_point
*int_red_y
,
2142 png_fixed_point
*int_green_x
, png_fixed_point
*int_green_y
,
2143 png_fixed_point
*int_blue_x
, png_fixed_point
*int_blue_y
))
2144 PNG_FIXED_EXPORT(231, png_uint_32
, png_get_cHRM_XYZ_fixed
,
2145 (png_const_structrp png_ptr
, png_const_inforp info_ptr
,
2146 png_fixed_point
*int_red_X
, png_fixed_point
*int_red_Y
,
2147 png_fixed_point
*int_red_Z
, png_fixed_point
*int_green_X
,
2148 png_fixed_point
*int_green_Y
, png_fixed_point
*int_green_Z
,
2149 png_fixed_point
*int_blue_X
, png_fixed_point
*int_blue_Y
,
2150 png_fixed_point
*int_blue_Z
))
2153 #ifdef PNG_cHRM_SUPPORTED
2154 PNG_FP_EXPORT(135, void, png_set_cHRM
, (png_const_structrp png_ptr
,
2155 png_inforp info_ptr
,
2156 double white_x
, double white_y
, double red_x
, double red_y
, double green_x
,
2157 double green_y
, double blue_x
, double blue_y
))
2158 PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ
, (png_const_structrp png_ptr
,
2159 png_inforp info_ptr
, double red_X
, double red_Y
, double red_Z
,
2160 double green_X
, double green_Y
, double green_Z
, double blue_X
,
2161 double blue_Y
, double blue_Z
))
2162 PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed
, (png_const_structrp png_ptr
,
2163 png_inforp info_ptr
, png_fixed_point int_white_x
,
2164 png_fixed_point int_white_y
, png_fixed_point int_red_x
,
2165 png_fixed_point int_red_y
, png_fixed_point int_green_x
,
2166 png_fixed_point int_green_y
, png_fixed_point int_blue_x
,
2167 png_fixed_point int_blue_y
))
2168 PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed
, (png_const_structrp png_ptr
,
2169 png_inforp info_ptr
, png_fixed_point int_red_X
, png_fixed_point int_red_Y
,
2170 png_fixed_point int_red_Z
, png_fixed_point int_green_X
,
2171 png_fixed_point int_green_Y
, png_fixed_point int_green_Z
,
2172 png_fixed_point int_blue_X
, png_fixed_point int_blue_Y
,
2173 png_fixed_point int_blue_Z
))
2176 #ifdef PNG_gAMA_SUPPORTED
2177 PNG_FP_EXPORT(137, png_uint_32
, png_get_gAMA
, (png_const_structrp png_ptr
,
2178 png_const_inforp info_ptr
, double *file_gamma
))
2179 PNG_FIXED_EXPORT(138, png_uint_32
, png_get_gAMA_fixed
,
2180 (png_const_structrp png_ptr
, png_const_inforp info_ptr
,
2181 png_fixed_point
*int_file_gamma
))
2184 #ifdef PNG_gAMA_SUPPORTED
2185 PNG_FP_EXPORT(139, void, png_set_gAMA
, (png_const_structrp png_ptr
,
2186 png_inforp info_ptr
, double file_gamma
))
2187 PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed
, (png_const_structrp png_ptr
,
2188 png_inforp info_ptr
, png_fixed_point int_file_gamma
))
2191 #ifdef PNG_hIST_SUPPORTED
2192 PNG_EXPORT(141, png_uint_32
, png_get_hIST
, (png_const_structrp png_ptr
,
2193 png_inforp info_ptr
, png_uint_16p
*hist
));
2196 #ifdef PNG_hIST_SUPPORTED
2197 PNG_EXPORT(142, void, png_set_hIST
, (png_const_structrp png_ptr
,
2198 png_inforp info_ptr
, png_const_uint_16p hist
));
2201 PNG_EXPORT(143, png_uint_32
, png_get_IHDR
, (png_const_structrp png_ptr
,
2202 png_const_inforp info_ptr
, png_uint_32
*width
, png_uint_32
*height
,
2203 int *bit_depth
, int *color_type
, int *interlace_method
,
2204 int *compression_method
, int *filter_method
));
2206 PNG_EXPORT(144, void, png_set_IHDR
, (png_const_structrp png_ptr
,
2207 png_inforp info_ptr
, png_uint_32 width
, png_uint_32 height
, int bit_depth
,
2208 int color_type
, int interlace_method
, int compression_method
,
2209 int filter_method
));
2211 #ifdef PNG_oFFs_SUPPORTED
2212 PNG_EXPORT(145, png_uint_32
, png_get_oFFs
, (png_const_structrp png_ptr
,
2213 png_const_inforp info_ptr
, png_int_32
*offset_x
, png_int_32
*offset_y
,
2217 #ifdef PNG_oFFs_SUPPORTED
2218 PNG_EXPORT(146, void, png_set_oFFs
, (png_const_structrp png_ptr
,
2219 png_inforp info_ptr
, png_int_32 offset_x
, png_int_32 offset_y
,
2223 #ifdef PNG_pCAL_SUPPORTED
2224 PNG_EXPORT(147, png_uint_32
, png_get_pCAL
, (png_const_structrp png_ptr
,
2225 png_inforp info_ptr
, png_charp
*purpose
, png_int_32
*X0
,
2226 png_int_32
*X1
, int *type
, int *nparams
, png_charp
*units
,
2227 png_charpp
*params
));
2230 #ifdef PNG_pCAL_SUPPORTED
2231 PNG_EXPORT(148, void, png_set_pCAL
, (png_const_structrp png_ptr
,
2232 png_inforp info_ptr
, png_const_charp purpose
, png_int_32 X0
, png_int_32 X1
,
2233 int type
, int nparams
, png_const_charp units
, png_charpp params
));
2236 #ifdef PNG_pHYs_SUPPORTED
2237 PNG_EXPORT(149, png_uint_32
, png_get_pHYs
, (png_const_structrp png_ptr
,
2238 png_const_inforp info_ptr
, png_uint_32
*res_x
, png_uint_32
*res_y
,
2242 #ifdef PNG_pHYs_SUPPORTED
2243 PNG_EXPORT(150, void, png_set_pHYs
, (png_const_structrp png_ptr
,
2244 png_inforp info_ptr
, png_uint_32 res_x
, png_uint_32 res_y
, int unit_type
));
2247 PNG_EXPORT(151, png_uint_32
, png_get_PLTE
, (png_const_structrp png_ptr
,
2248 png_inforp info_ptr
, png_colorp
*palette
, int *num_palette
));
2250 PNG_EXPORT(152, void, png_set_PLTE
, (png_structrp png_ptr
,
2251 png_inforp info_ptr
, png_const_colorp palette
, int num_palette
));
2253 #ifdef PNG_sBIT_SUPPORTED
2254 PNG_EXPORT(153, png_uint_32
, png_get_sBIT
, (png_const_structrp png_ptr
,
2255 png_inforp info_ptr
, png_color_8p
*sig_bit
));
2258 #ifdef PNG_sBIT_SUPPORTED
2259 PNG_EXPORT(154, void, png_set_sBIT
, (png_const_structrp png_ptr
,
2260 png_inforp info_ptr
, png_const_color_8p sig_bit
));
2263 #ifdef PNG_sRGB_SUPPORTED
2264 PNG_EXPORT(155, png_uint_32
, png_get_sRGB
, (png_const_structrp png_ptr
,
2265 png_const_inforp info_ptr
, int *file_srgb_intent
));
2268 #ifdef PNG_sRGB_SUPPORTED
2269 PNG_EXPORT(156, void, png_set_sRGB
, (png_const_structrp png_ptr
,
2270 png_inforp info_ptr
, int srgb_intent
));
2271 PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM
, (png_const_structrp png_ptr
,
2272 png_inforp info_ptr
, int srgb_intent
));
2275 #ifdef PNG_iCCP_SUPPORTED
2276 PNG_EXPORT(158, png_uint_32
, png_get_iCCP
, (png_const_structrp png_ptr
,
2277 png_inforp info_ptr
, png_charpp name
, int *compression_type
,
2278 png_bytepp profile
, png_uint_32
*proflen
));
2281 #ifdef PNG_iCCP_SUPPORTED
2282 PNG_EXPORT(159, void, png_set_iCCP
, (png_const_structrp png_ptr
,
2283 png_inforp info_ptr
, png_const_charp name
, int compression_type
,
2284 png_const_bytep profile
, png_uint_32 proflen
));
2287 #ifdef PNG_sPLT_SUPPORTED
2288 PNG_EXPORT(160, int, png_get_sPLT
, (png_const_structrp png_ptr
,
2289 png_inforp info_ptr
, png_sPLT_tpp entries
));
2292 #ifdef PNG_sPLT_SUPPORTED
2293 PNG_EXPORT(161, void, png_set_sPLT
, (png_const_structrp png_ptr
,
2294 png_inforp info_ptr
, png_const_sPLT_tp entries
, int nentries
));
2297 #ifdef PNG_TEXT_SUPPORTED
2298 /* png_get_text also returns the number of text chunks in *num_text */
2299 PNG_EXPORT(162, int, png_get_text
, (png_const_structrp png_ptr
,
2300 png_inforp info_ptr
, png_textp
*text_ptr
, int *num_text
));
2303 /* Note while png_set_text() will accept a structure whose text,
2304 * language, and translated keywords are NULL pointers, the structure
2305 * returned by png_get_text will always contain regular
2306 * zero-terminated C strings. They might be empty strings but
2307 * they will never be NULL pointers.
2310 #ifdef PNG_TEXT_SUPPORTED
2311 PNG_EXPORT(163, void, png_set_text
, (png_const_structrp png_ptr
,
2312 png_inforp info_ptr
, png_const_textp text_ptr
, int num_text
));
2315 #ifdef PNG_tIME_SUPPORTED
2316 PNG_EXPORT(164, png_uint_32
, png_get_tIME
, (png_const_structrp png_ptr
,
2317 png_inforp info_ptr
, png_timep
*mod_time
));
2320 #ifdef PNG_tIME_SUPPORTED
2321 PNG_EXPORT(165, void, png_set_tIME
, (png_const_structrp png_ptr
,
2322 png_inforp info_ptr
, png_const_timep mod_time
));
2325 #ifdef PNG_tRNS_SUPPORTED
2326 PNG_EXPORT(166, png_uint_32
, png_get_tRNS
, (png_const_structrp png_ptr
,
2327 png_inforp info_ptr
, png_bytep
*trans_alpha
, int *num_trans
,
2328 png_color_16p
*trans_color
));
2331 #ifdef PNG_tRNS_SUPPORTED
2332 PNG_EXPORT(167, void, png_set_tRNS
, (png_structrp png_ptr
,
2333 png_inforp info_ptr
, png_const_bytep trans_alpha
, int num_trans
,
2334 png_const_color_16p trans_color
));
2337 #ifdef PNG_sCAL_SUPPORTED
2338 PNG_FP_EXPORT(168, png_uint_32
, png_get_sCAL
, (png_const_structrp png_ptr
,
2339 png_const_inforp info_ptr
, int *unit
, double *width
, double *height
))
2340 #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
2341 defined(PNG_FLOATING_POINT_SUPPORTED)
2342 /* NOTE: this API is currently implemented using floating point arithmetic,
2343 * consequently it can only be used on systems with floating point support.
2344 * In any case the range of values supported by png_fixed_point is small and it
2345 * is highly recommended that png_get_sCAL_s be used instead.
2347 PNG_FIXED_EXPORT(214, png_uint_32
, png_get_sCAL_fixed
,
2348 (png_const_structrp png_ptr
, png_const_inforp info_ptr
, int *unit
,
2349 png_fixed_point
*width
, png_fixed_point
*height
))
2351 PNG_EXPORT(169, png_uint_32
, png_get_sCAL_s
,
2352 (png_const_structrp png_ptr
, png_const_inforp info_ptr
, int *unit
,
2353 png_charpp swidth
, png_charpp sheight
));
2355 PNG_FP_EXPORT(170, void, png_set_sCAL
, (png_const_structrp png_ptr
,
2356 png_inforp info_ptr
, int unit
, double width
, double height
))
2357 PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed
, (png_const_structrp png_ptr
,
2358 png_inforp info_ptr
, int unit
, png_fixed_point width
,
2359 png_fixed_point height
))
2360 PNG_EXPORT(171, void, png_set_sCAL_s
, (png_const_structrp png_ptr
,
2361 png_inforp info_ptr
, int unit
,
2362 png_const_charp swidth
, png_const_charp sheight
));
2363 #endif /* PNG_sCAL_SUPPORTED */
2365 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2366 /* Provide the default handling for all unknown chunks or, optionally, for
2367 * specific unknown chunks.
2369 * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
2370 * ignored and the default was used, the per-chunk setting only had an effect on
2371 * write. If you wish to have chunk-specific handling on read in code that must
2372 * work on earlier versions you must use a user chunk callback to specify the
2373 * desired handling (keep or discard.)
2375 * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below. The
2376 * parameter is interpreted as follows:
2379 * PNG_HANDLE_CHUNK_AS_DEFAULT:
2380 * Known chunks: do normal libpng processing, do not keep the chunk (but
2381 * see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
2382 * Unknown chunks: for a specific chunk use the global default, when used
2383 * as the default discard the chunk data.
2384 * PNG_HANDLE_CHUNK_NEVER:
2385 * Discard the chunk data.
2386 * PNG_HANDLE_CHUNK_IF_SAFE:
2387 * Keep the chunk data if the chunk is not critical else raise a chunk
2389 * PNG_HANDLE_CHUNK_ALWAYS:
2390 * Keep the chunk data.
2392 * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
2393 * below. Notice that specifying "AS_DEFAULT" as a global default is equivalent
2394 * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
2395 * it simply resets the behavior to the libpng default.
2397 * INTERACTION WTIH USER CHUNK CALLBACKS:
2398 * The per-chunk handling is always used when there is a png_user_chunk_ptr
2399 * callback and the callback returns 0; the chunk is then always stored *unless*
2400 * it is critical and the per-chunk setting is other than ALWAYS. Notice that
2401 * the global default is *not* used in this case. (In effect the per-chunk
2402 * value is incremented to at least IF_SAFE.)
2404 * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
2405 * per-chunk defaults will be honored. If you want to preserve the current
2406 * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
2407 * as the default - if you don't do this libpng 1.6 will issue a warning.
2409 * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
2410 * earlier simply return '1' (handled).
2412 * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
2413 * If this is *not* set known chunks will always be handled by libpng and
2414 * will never be stored in the unknown chunk list. Known chunks listed to
2415 * png_set_keep_unknown_chunks will have no effect. If it is set then known
2416 * chunks listed with a keep other than AS_DEFAULT will *never* be processed
2417 * by libpng, in addition critical chunks must either be processed by the
2418 * callback or saved.
2420 * The IHDR and IEND chunks must not be listed. Because this turns off the
2421 * default handling for chunks that would otherwise be recognized the
2422 * behavior of libpng transformations may well become incorrect!
2425 * When writing chunks the options only apply to the chunks specified by
2426 * png_set_unknown_chunks (below), libpng will *always* write known chunks
2427 * required by png_set_ calls and will always write the core critical chunks
2428 * (as required for PLTE).
2430 * Each chunk in the png_set_unknown_chunks list is looked up in the
2431 * png_set_keep_unknown_chunks list to find the keep setting, this is then
2432 * interpreted as follows:
2434 * PNG_HANDLE_CHUNK_AS_DEFAULT:
2435 * Write safe-to-copy chunks and write other chunks if the global
2436 * default is set to _ALWAYS, otherwise don't write this chunk.
2437 * PNG_HANDLE_CHUNK_NEVER:
2438 * Do not write the chunk.
2439 * PNG_HANDLE_CHUNK_IF_SAFE:
2440 * Write the chunk if it is safe-to-copy, otherwise do not write it.
2441 * PNG_HANDLE_CHUNK_ALWAYS:
2444 * Note that the default behavior is effectively the opposite of the read case -
2445 * in read unknown chunks are not stored by default, in write they are written
2446 * by default. Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
2447 * - on write the safe-to-copy bit is checked, on read the critical bit is
2448 * checked and on read if the chunk is critical an error will be raised.
2452 * If num_chunks is positive, then the "keep" parameter specifies the manner
2453 * for handling only those chunks appearing in the chunk_list array,
2454 * otherwise the chunk list array is ignored.
2456 * If num_chunks is 0 the "keep" parameter specifies the default behavior for
2457 * unknown chunks, as described above.
2459 * If num_chunks is negative, then the "keep" parameter specifies the manner
2460 * for handling all unknown chunks plus all chunks recognized by libpng
2461 * except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
2462 * be processed by libpng.
2464 PNG_EXPORT(172, void, png_set_keep_unknown_chunks
, (png_structrp png_ptr
,
2465 int keep
, png_const_bytep chunk_list
, int num_chunks
));
2467 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
2468 * the result is therefore true (non-zero) if special handling is required,
2469 * false for the default handling.
2471 PNG_EXPORT(173, int, png_handle_as_unknown
, (png_const_structrp png_ptr
,
2472 png_const_bytep chunk_name
));
2475 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2476 PNG_EXPORT(174, void, png_set_unknown_chunks
, (png_const_structrp png_ptr
,
2477 png_inforp info_ptr
, png_const_unknown_chunkp unknowns
,
2479 /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
2480 * unknowns to the location currently stored in the png_struct. This is
2481 * invariably the wrong value on write. To fix this call the following API
2482 * for each chunk in the list with the correct location. If you know your
2483 * code won't be compiled on earlier versions you can rely on
2484 * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
2485 * the correct thing.
2488 PNG_EXPORT(175, void, png_set_unknown_chunk_location
,
2489 (png_const_structrp png_ptr
, png_inforp info_ptr
, int chunk
, int location
));
2491 PNG_EXPORT(176, int, png_get_unknown_chunks
, (png_const_structrp png_ptr
,
2492 png_inforp info_ptr
, png_unknown_chunkpp entries
));
2495 /* Png_free_data() will turn off the "valid" flag for anything it frees.
2496 * If you need to turn it off for a chunk that your application has freed,
2497 * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
2499 PNG_EXPORT(177, void, png_set_invalid
, (png_const_structrp png_ptr
,
2500 png_inforp info_ptr
, int mask
));
2502 #ifdef PNG_INFO_IMAGE_SUPPORTED
2503 /* The "params" pointer is currently not used and is for future expansion. */
2504 PNG_EXPORT(178, void, png_read_png
, (png_structrp png_ptr
, png_inforp info_ptr
,
2505 int transforms
, png_voidp params
));
2506 PNG_EXPORT(179, void, png_write_png
, (png_structrp png_ptr
, png_inforp info_ptr
,
2507 int transforms
, png_voidp params
));
2510 PNG_EXPORT(180, png_const_charp
, png_get_copyright
,
2511 (png_const_structrp png_ptr
));
2512 PNG_EXPORT(181, png_const_charp
, png_get_header_ver
,
2513 (png_const_structrp png_ptr
));
2514 PNG_EXPORT(182, png_const_charp
, png_get_header_version
,
2515 (png_const_structrp png_ptr
));
2516 PNG_EXPORT(183, png_const_charp
, png_get_libpng_ver
,
2517 (png_const_structrp png_ptr
));
2519 #ifdef PNG_MNG_FEATURES_SUPPORTED
2520 PNG_EXPORT(184, png_uint_32
, png_permit_mng_features
, (png_structrp png_ptr
,
2521 png_uint_32 mng_features_permitted
));
2524 /* For use in png_set_keep_unknown, added to version 1.2.6 */
2525 #define PNG_HANDLE_CHUNK_AS_DEFAULT 0
2526 #define PNG_HANDLE_CHUNK_NEVER 1
2527 #define PNG_HANDLE_CHUNK_IF_SAFE 2
2528 #define PNG_HANDLE_CHUNK_ALWAYS 3
2529 #define PNG_HANDLE_CHUNK_LAST 4
2531 /* Strip the prepended error numbers ("#nnn ") from error and warning
2532 * messages before passing them to the error or warning handler.
2534 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
2535 PNG_EXPORT(185, void, png_set_strip_error_numbers
, (png_structrp png_ptr
,
2536 png_uint_32 strip_mode
));
2539 /* Added in libpng-1.2.6 */
2540 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
2541 PNG_EXPORT(186, void, png_set_user_limits
, (png_structrp png_ptr
,
2542 png_uint_32 user_width_max
, png_uint_32 user_height_max
));
2543 PNG_EXPORT(187, png_uint_32
, png_get_user_width_max
,
2544 (png_const_structrp png_ptr
));
2545 PNG_EXPORT(188, png_uint_32
, png_get_user_height_max
,
2546 (png_const_structrp png_ptr
));
2547 /* Added in libpng-1.4.0 */
2548 PNG_EXPORT(189, void, png_set_chunk_cache_max
, (png_structrp png_ptr
,
2549 png_uint_32 user_chunk_cache_max
));
2550 PNG_EXPORT(190, png_uint_32
, png_get_chunk_cache_max
,
2551 (png_const_structrp png_ptr
));
2552 /* Added in libpng-1.4.1 */
2553 PNG_EXPORT(191, void, png_set_chunk_malloc_max
, (png_structrp png_ptr
,
2554 png_alloc_size_t user_chunk_cache_max
));
2555 PNG_EXPORT(192, png_alloc_size_t
, png_get_chunk_malloc_max
,
2556 (png_const_structrp png_ptr
));
2559 #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
2560 PNG_EXPORT(193, png_uint_32
, png_get_pixels_per_inch
,
2561 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2563 PNG_EXPORT(194, png_uint_32
, png_get_x_pixels_per_inch
,
2564 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2566 PNG_EXPORT(195, png_uint_32
, png_get_y_pixels_per_inch
,
2567 (png_const_structrp png_ptr
, png_const_inforp info_ptr
));
2569 PNG_FP_EXPORT(196, float, png_get_x_offset_inches
,
2570 (png_const_structrp png_ptr
, png_const_inforp info_ptr
))
2571 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2572 PNG_FIXED_EXPORT(211, png_fixed_point
, png_get_x_offset_inches_fixed
,
2573 (png_const_structrp png_ptr
, png_const_inforp info_ptr
))
2576 PNG_FP_EXPORT(197, float, png_get_y_offset_inches
, (png_const_structrp png_ptr
,
2577 png_const_inforp info_ptr
))
2578 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2579 PNG_FIXED_EXPORT(212, png_fixed_point
, png_get_y_offset_inches_fixed
,
2580 (png_const_structrp png_ptr
, png_const_inforp info_ptr
))
2583 # ifdef PNG_pHYs_SUPPORTED
2584 PNG_EXPORT(198, png_uint_32
, png_get_pHYs_dpi
, (png_const_structrp png_ptr
,
2585 png_const_inforp info_ptr
, png_uint_32
*res_x
, png_uint_32
*res_y
,
2587 # endif /* PNG_pHYs_SUPPORTED */
2588 #endif /* PNG_INCH_CONVERSIONS_SUPPORTED */
2590 /* Added in libpng-1.4.0 */
2591 #ifdef PNG_IO_STATE_SUPPORTED
2592 PNG_EXPORT(199, png_uint_32
, png_get_io_state
, (png_const_structrp png_ptr
));
2594 /* Removed from libpng 1.6; use png_get_io_chunk_type. */
2595 PNG_REMOVED(200, png_const_bytep
, png_get_io_chunk_name
, (png_structrp png_ptr
),
2598 PNG_EXPORT(216, png_uint_32
, png_get_io_chunk_type
,
2599 (png_const_structrp png_ptr
));
2601 /* The flags returned by png_get_io_state() are the following: */
2602 # define PNG_IO_NONE 0x0000 /* no I/O at this moment */
2603 # define PNG_IO_READING 0x0001 /* currently reading */
2604 # define PNG_IO_WRITING 0x0002 /* currently writing */
2605 # define PNG_IO_SIGNATURE 0x0010 /* currently at the file signature */
2606 # define PNG_IO_CHUNK_HDR 0x0020 /* currently at the chunk header */
2607 # define PNG_IO_CHUNK_DATA 0x0040 /* currently at the chunk data */
2608 # define PNG_IO_CHUNK_CRC 0x0080 /* currently at the chunk crc */
2609 # define PNG_IO_MASK_OP 0x000f /* current operation: reading/writing */
2610 # define PNG_IO_MASK_LOC 0x00f0 /* current location: sig/hdr/data/crc */
2611 #endif /* ?PNG_IO_STATE_SUPPORTED */
2613 /* Interlace support. The following macros are always defined so that if
2614 * libpng interlace handling is turned off the macros may be used to handle
2615 * interlaced images within the application.
2617 #define PNG_INTERLACE_ADAM7_PASSES 7
2619 /* Two macros to return the first row and first column of the original,
2620 * full, image which appears in a given pass. 'pass' is in the range 0
2621 * to 6 and the result is in the range 0 to 7.
2623 #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
2624 #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
2626 /* A macro to return the offset between pixels in the output row for a pair of
2627 * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
2628 * follows. Note that ROW_OFFSET is the offset from one row to the next whereas
2629 * COL_OFFSET is from one column to the next, within a row.
2631 #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
2632 #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
2634 /* Two macros to help evaluate the number of rows or columns in each
2635 * pass. This is expressed as a shift - effectively log2 of the number or
2636 * rows or columns in each 8x8 tile of the original image.
2638 #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
2639 #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
2641 /* Hence two macros to determine the number of rows or columns in a given
2642 * pass of an image given its height or width. In fact these macros may
2643 * return non-zero even though the sub-image is empty, because the other
2644 * dimension may be empty for a small image.
2646 #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
2647 -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
2648 #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
2649 -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
2651 /* For the reader row callbacks (both progressive and sequential) it is
2652 * necessary to find the row in the output image given a row in an interlaced
2653 * image, so two more macros:
2655 #define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
2656 (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
2657 #define PNG_COL_FROM_PASS_COL(x_in, pass) \
2658 (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
2660 /* Two macros which return a boolean (0 or 1) saying whether the given row
2661 * or column is in a particular pass. These use a common utility macro that
2662 * returns a mask for a given pass - the offset 'off' selects the row or
2663 * column version. The mask has the appropriate bit set for each column in
2666 #define PNG_PASS_MASK(pass,off) ( \
2667 ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
2668 ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
2670 #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
2671 ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
2672 #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
2673 ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
2675 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
2676 /* With these routines we avoid an integer divide, which will be slower on
2677 * most machines. However, it does take more operations than the corresponding
2678 * divide method, so it may be slower on a few RISC systems. There are two
2679 * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
2681 * Note that the rounding factors are NOT supposed to be the same! 128 and
2682 * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
2685 * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
2688 /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
2690 # define png_composite(composite, fg, alpha, bg) \
2691 { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
2692 * (png_uint_16)(alpha) \
2693 + (png_uint_16)(bg)*(png_uint_16)(255 \
2694 - (png_uint_16)(alpha)) + 128); \
2695 (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
2697 # define png_composite_16(composite, fg, alpha, bg) \
2698 { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
2699 * (png_uint_32)(alpha) \
2700 + (png_uint_32)(bg)*(65535 \
2701 - (png_uint_32)(alpha)) + 32768); \
2702 (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
2704 #else /* Standard method using integer division */
2706 # define png_composite(composite, fg, alpha, bg) \
2707 (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) + \
2708 (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
2711 # define png_composite_16(composite, fg, alpha, bg) \
2712 (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
2713 (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) + \
2715 #endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */
2717 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
2718 PNG_EXPORT(201, png_uint_32
, png_get_uint_32
, (png_const_bytep buf
));
2719 PNG_EXPORT(202, png_uint_16
, png_get_uint_16
, (png_const_bytep buf
));
2720 PNG_EXPORT(203, png_int_32
, png_get_int_32
, (png_const_bytep buf
));
2723 PNG_EXPORT(204, png_uint_32
, png_get_uint_31
, (png_const_structrp png_ptr
,
2724 png_const_bytep buf
));
2725 /* No png_get_int_16 -- may be added if there's a real need for it. */
2727 /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
2728 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2729 PNG_EXPORT(205, void, png_save_uint_32
, (png_bytep buf
, png_uint_32 i
));
2731 #ifdef PNG_SAVE_INT_32_SUPPORTED
2732 PNG_EXPORT(206, void, png_save_int_32
, (png_bytep buf
, png_int_32 i
));
2735 /* Place a 16-bit number into a buffer in PNG byte order.
2736 * The parameter is declared unsigned int, not png_uint_16,
2737 * just to avoid potential problems on pre-ANSI C compilers.
2739 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2740 PNG_EXPORT(207, void, png_save_uint_16
, (png_bytep buf
, unsigned int i
));
2741 /* No png_save_int_16 -- may be added if there's a real need for it. */
2744 #ifdef PNG_USE_READ_MACROS
2745 /* Inline macros to do direct reads of bytes from the input buffer.
2746 * The png_get_int_32() routine assumes we are using two's complement
2747 * format for negative values, which is almost certainly true.
2749 # define PNG_get_uint_32(buf) \
2750 (((png_uint_32)(*(buf)) << 24) + \
2751 ((png_uint_32)(*((buf) + 1)) << 16) + \
2752 ((png_uint_32)(*((buf) + 2)) << 8) + \
2753 ((png_uint_32)(*((buf) + 3))))
2755 /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
2756 * function) incorrectly returned a value of type png_uint_32.
2758 # define PNG_get_uint_16(buf) \
2760 (((unsigned int)(*(buf)) << 8) + \
2761 ((unsigned int)(*((buf) + 1)))))
2763 # define PNG_get_int_32(buf) \
2764 ((png_int_32)((*(buf) & 0x80) \
2765 ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
2766 : (png_int_32)png_get_uint_32(buf)))
2768 /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
2769 * but defining a macro name prefixed with PNG_PREFIX.
2772 # define png_get_uint_32(buf) PNG_get_uint_32(buf)
2773 # define png_get_uint_16(buf) PNG_get_uint_16(buf)
2774 # define png_get_int_32(buf) PNG_get_int_32(buf)
2778 /* No macros; revert to the (redefined) function */
2779 # define PNG_get_uint_32 (png_get_uint_32)
2780 # define PNG_get_uint_16 (png_get_uint_16)
2781 # define PNG_get_int_32 (png_get_int_32)
2785 /*******************************************************************************
2787 *******************************************************************************
2789 * Please read the documentation in libpng-manual.txt (TODO: write said
2790 * documentation) if you don't understand what follows.
2792 * The simplified API hides the details of both libpng and the PNG file format
2793 * itself. It allows PNG files to be read into a very limited number of
2794 * in-memory bitmap formats or to be written from the same formats. If these
2795 * formats do not accomodate your needs then you can, and should, use the more
2796 * sophisticated APIs above - these support a wide variety of in-memory formats
2797 * and a wide variety of sophisticated transformations to those formats as well
2798 * as a wide variety of APIs to manipulate ancillary information.
2800 * To read a PNG file using the simplified API:
2802 * 1) Declare a 'png_image' structure (see below) on the stack and set the
2803 * version field to PNG_IMAGE_VERSION.
2804 * 2) Call the appropriate png_image_begin_read... function.
2805 * 3) Set the png_image 'format' member to the required sample format.
2806 * 4) Allocate a buffer for the image and, if required, the color-map.
2807 * 5) Call png_image_finish_read to read the image and, if required, the
2808 * color-map into your buffers.
2810 * There are no restrictions on the format of the PNG input itself; all valid
2811 * color types, bit depths, and interlace methods are acceptable, and the
2812 * input image is transformed as necessary to the requested in-memory format
2813 * during the png_image_finish_read() step. The only caveat is that if you
2814 * request a color-mapped image from a PNG that is full-color or makes
2815 * complex use of an alpha channel the transformation is extremely lossy and the
2816 * result may look terrible.
2818 * To write a PNG file using the simplified API:
2820 * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
2821 * 2) Initialize the members of the structure that describe the image, setting
2822 * the 'format' member to the format of the image samples.
2823 * 3) Call the appropriate png_image_write... function with a pointer to the
2824 * image and, if necessary, the color-map to write the PNG data.
2826 * png_image is a structure that describes the in-memory format of an image
2827 * when it is being read or defines the in-memory format of an image that you
2830 #define PNG_IMAGE_VERSION 1
2832 typedef struct png_control
*png_controlp
;
2835 png_controlp opaque
; /* Initialize to NULL, free with png_image_free */
2836 png_uint_32 version
; /* Set to PNG_IMAGE_VERSION */
2837 png_uint_32 width
; /* Image width in pixels (columns) */
2838 png_uint_32 height
; /* Image height in pixels (rows) */
2839 png_uint_32 format
; /* Image format as defined below */
2840 png_uint_32 flags
; /* A bit mask containing informational flags */
2841 png_uint_32 colormap_entries
;
2842 /* Number of entries in the color-map */
2844 /* In the event of an error or warning the following field will be set to a
2845 * non-zero value and the 'message' field will contain a '\0' terminated
2846 * string with the libpng error or warning message. If both warnings and
2847 * an error were encountered, only the error is recorded. If there
2848 * are multiple warnings, only the first one is recorded.
2850 * The upper 30 bits of this value are reserved, the low two bits contain
2851 * a value as follows:
2853 # define PNG_IMAGE_WARNING 1
2854 # define PNG_IMAGE_ERROR 2
2856 * The result is a two bit code such that a value more than 1 indicates
2857 * a failure in the API just called:
2859 * 0 - no warning or error
2862 * 3 - error preceded by warning
2864 # define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
2866 png_uint_32 warning_or_error
;
2869 } png_image
, *png_imagep
;
2871 /* The samples of the image have one to four channels whose components have
2872 * original values in the range 0 to 1.0:
2874 * 1: A single gray or luminance channel (G).
2875 * 2: A gray/luminance channel and an alpha channel (GA).
2876 * 3: Three red, green, blue color channels (RGB).
2877 * 4: Three color channels and an alpha channel (RGBA).
2879 * The components are encoded in one of two ways:
2881 * a) As a small integer, value 0..255, contained in a single byte. For the
2882 * alpha channel the original value is simply value/255. For the color or
2883 * luminance channels the value is encoded according to the sRGB specification
2884 * and matches the 8-bit format expected by typical display devices.
2886 * The color/gray channels are not scaled (pre-multiplied) by the alpha
2887 * channel and are suitable for passing to color management software.
2889 * b) As a value in the range 0..65535, contained in a 2-byte integer. All
2890 * channels can be converted to the original value by dividing by 65535; all
2891 * channels are linear. Color channels use the RGB encoding (RGB end-points) of
2892 * the sRGB specification. This encoding is identified by the
2893 * PNG_FORMAT_FLAG_LINEAR flag below.
2895 * When the simplified API needs to convert between sRGB and linear colorspaces,
2896 * the actual sRGB transfer curve defined in the sRGB specification (see the
2897 * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
2898 * approximation used elsewhere in libpng.
2900 * When an alpha channel is present it is expected to denote pixel coverage
2901 * of the color or luminance channels and is returned as an associated alpha
2902 * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
2905 * The samples are either contained directly in the image data, between 1 and 8
2906 * bytes per pixel according to the encoding, or are held in a color-map indexed
2907 * by bytes in the image data. In the case of a color-map the color-map entries
2908 * are individual samples, encoded as above, and the image data has one byte per
2909 * pixel to select the relevant sample from the color-map.
2914 * #defines to be used in png_image::format. Each #define identifies a
2915 * particular layout of sample data and, if present, alpha values. There are
2916 * separate defines for each of the two component encodings.
2918 * A format is built up using single bit flag values. All combinations are
2919 * valid. Formats can be built up from the flag values or you can use one of
2920 * the predefined values below. When testing formats always use the FORMAT_FLAG
2921 * macros to test for individual features - future versions of the library may
2924 * When reading or writing color-mapped images the format should be set to the
2925 * format of the entries in the color-map then png_image_{read,write}_colormap
2926 * called to read or write the color-map and set the format correctly for the
2927 * image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
2929 * NOTE: libpng can be built with particular features disabled, if you see
2930 * compiler errors because the definition of one of the following flags has been
2931 * compiled out it is because libpng does not have the required support. It is
2932 * possible, however, for the libpng configuration to enable the format on just
2933 * read or just write; in that case you may see an error at run time. You can
2934 * guard against this by checking for the definition of the appropriate
2935 * "_SUPPORTED" macro, one of:
2937 * PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
2939 #define PNG_FORMAT_FLAG_ALPHA 0x01U /* format with an alpha channel */
2940 #define PNG_FORMAT_FLAG_COLOR 0x02U /* color format: otherwise grayscale */
2941 #define PNG_FORMAT_FLAG_LINEAR 0x04U /* 2 byte channels else 1 byte */
2942 #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
2944 #ifdef PNG_FORMAT_BGR_SUPPORTED
2945 # define PNG_FORMAT_FLAG_BGR 0x10U /* BGR colors, else order is RGB */
2948 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
2949 # define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
2952 /* Commonly used formats have predefined macros.
2954 * First the single byte (sRGB) formats:
2956 #define PNG_FORMAT_GRAY 0
2957 #define PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA
2958 #define PNG_FORMAT_AG (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
2959 #define PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR
2960 #define PNG_FORMAT_BGR (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
2961 #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
2962 #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
2963 #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
2964 #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
2966 /* Then the linear 2-byte formats. When naming these "Y" is used to
2967 * indicate a luminance (gray) channel.
2969 #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
2970 #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
2971 #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
2972 #define PNG_FORMAT_LINEAR_RGB_ALPHA \
2973 (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
2975 /* With color-mapped formats the image data is one byte for each pixel, the byte
2976 * is an index into the color-map which is formatted as above. To obtain a
2977 * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
2978 * to one of the above definitions, or you can use one of the definitions below.
2980 #define PNG_FORMAT_RGB_COLORMAP (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
2981 #define PNG_FORMAT_BGR_COLORMAP (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
2982 #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
2983 #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
2984 #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
2985 #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
2989 * These are convenience macros to derive information from a png_image
2990 * structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
2991 * actual image sample values - either the entries in the color-map or the
2992 * pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
2993 * for the pixels and will always return 1 for color-mapped formats. The
2994 * remaining macros return information about the rows in the image and the
2997 * NOTE: All the macros that take a png_image::format parameter are compile time
2998 * constants if the format parameter is, itself, a constant. Therefore these
2999 * macros can be used in array declarations and case labels where required.
3000 * Similarly the macros are also pre-processor constants (sizeof is not used) so
3001 * they can be used in #if tests.
3003 * First the information about the samples.
3005 #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
3006 (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
3007 /* Return the total number of channels in a given format: 1..4 */
3009 #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
3010 ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
3011 /* Return the size in bytes of a single component of a pixel or color-map
3012 * entry (as appropriate) in the image: 1 or 2.
3015 #define PNG_IMAGE_SAMPLE_SIZE(fmt)\
3016 (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
3017 /* This is the size of the sample data for one sample. If the image is
3018 * color-mapped it is the size of one color-map entry (and image pixels are
3019 * one byte in size), otherwise it is the size of one image pixel.
3022 #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
3023 (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
3024 /* The maximum size of the color-map required by the format expressed in a
3025 * count of components. This can be used to compile-time allocate a
3028 * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
3030 * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
3032 * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
3033 * information from one of the png_image_begin_read_ APIs and dynamically
3034 * allocate the required memory.
3037 /* Corresponding information about the pixels */
3038 #define PNG_IMAGE_PIXEL_(test,fmt)\
3039 (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
3041 #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
3042 PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
3043 /* The number of separate channels (components) in a pixel; 1 for a
3044 * color-mapped image.
3047 #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
3048 PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
3049 /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
3053 #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
3054 /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
3056 /* Information about the whole row, or whole image */
3057 #define PNG_IMAGE_ROW_STRIDE(image)\
3058 (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
3059 /* Return the total number of components in a single row of the image; this
3060 * is the minimum 'row stride', the minimum count of components between each
3061 * row. For a color-mapped image this is the minimum number of bytes in a
3065 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
3066 (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
3067 /* Return the size, in bytes, of an image buffer given a png_image and a row
3068 * stride - the number of components to leave space for in each row.
3071 #define PNG_IMAGE_SIZE(image)\
3072 PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
3073 /* Return the size, in bytes, of the image in memory given just a png_image;
3074 * the row stride is the minimum stride required for the image.
3077 #define PNG_IMAGE_COLORMAP_SIZE(image)\
3078 (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
3079 /* Return the size, in bytes, of the color-map of this image. If the image
3080 * format is not a color-map format this will return a size sufficient for
3081 * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
3082 * you don't want to allocate a color-map in this case.
3087 * Flags containing additional information about the image are held in the
3088 * 'flags' field of png_image.
3090 #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
3091 /* This indicates the the RGB values of the in-memory bitmap do not
3092 * correspond to the red, green and blue end-points defined by sRGB.
3095 #define PNG_IMAGE_FLAG_FAST 0x02
3096 /* On write emphasise speed over compression; the resultant PNG file will be
3097 * larger but will be produced significantly faster, particular for large
3098 * images. Do not use this option for images which will be distributed, only
3099 * used it when producing intermediate files that will be read back in
3100 * repeatedly. For a typical 24-bit image the option will double the read
3101 * speed at the cost of increasing the image size by 25%, however for many
3102 * more compressible images the PNG file can be 10 times larger with only a
3103 * slight speed gain.
3106 #define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
3107 /* On read if the image is a 16-bit per component image and there is no gAMA
3108 * or sRGB chunk assume that the components are sRGB encoded. Notice that
3109 * images output by the simplified API always have gamma information; setting
3110 * this flag only affects the interpretation of 16-bit images from an
3111 * external source. It is recommended that the application expose this flag
3112 * to the user; the user can normally easily recognize the difference between
3113 * linear and sRGB encoding. This flag has no effect on write - the data
3114 * passed to the write APIs must have the correct encoding (as defined
3117 * If the flag is not set (the default) input 16-bit per component data is
3118 * assumed to be linear.
3120 * NOTE: the flag can only be set after the png_image_begin_read_ call,
3121 * because that call initializes the 'flags' field.
3124 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
3128 * The png_image passed to the read APIs must have been initialized by setting
3129 * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
3131 #ifdef PNG_STDIO_SUPPORTED
3132 PNG_EXPORT(234, int, png_image_begin_read_from_file
, (png_imagep image
,
3133 const char *file_name
));
3134 /* The named file is opened for read and the image header is filled in
3135 * from the PNG header in the file.
3138 PNG_EXPORT(235, int, png_image_begin_read_from_stdio
, (png_imagep image
,
3140 /* The PNG header is read from the stdio FILE object. */
3141 #endif /* PNG_STDIO_SUPPORTED */
3143 PNG_EXPORT(236, int, png_image_begin_read_from_memory
, (png_imagep image
,
3144 png_const_voidp memory
, png_size_t size
));
3145 /* The PNG header is read from the given memory buffer. */
3147 PNG_EXPORT(237, int, png_image_finish_read
, (png_imagep image
,
3148 png_const_colorp background
, void *buffer
, png_int_32 row_stride
,
3150 /* Finish reading the image into the supplied buffer and clean up the
3151 * png_image structure.
3153 * row_stride is the step, in byte or 2-byte units as appropriate,
3154 * between adjacent rows. A positive stride indicates that the top-most row
3155 * is first in the buffer - the normal top-down arrangement. A negative
3156 * stride indicates that the bottom-most row is first in the buffer.
3158 * background need only be supplied if an alpha channel must be removed from
3159 * a png_byte format and the removal is to be done by compositing on a solid
3160 * color; otherwise it may be NULL and any composition will be done directly
3161 * onto the buffer. The value is an sRGB color to use for the background,
3162 * for grayscale output the green channel is used.
3164 * background must be supplied when an alpha channel must be removed from a
3165 * single byte color-mapped output format, in other words if:
3167 * 1) The original format from png_image_begin_read_from_* had
3168 * PNG_FORMAT_FLAG_ALPHA set.
3169 * 2) The format set by the application does not.
3170 * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
3171 * PNG_FORMAT_FLAG_LINEAR *not* set.
3173 * For linear output removing the alpha channel is always done by compositing
3174 * on black and background is ignored.
3176 * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set. It must
3177 * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
3178 * image->colormap_entries will be updated to the actual number of entries
3179 * written to the colormap; this may be less than the original value.
3182 PNG_EXPORT(238, void, png_image_free
, (png_imagep image
));
3183 /* Free any data allocated by libpng in image->opaque, setting the pointer to
3184 * NULL. May be called at any time after the structure is initialized.
3186 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
3188 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3191 * For write you must initialize a png_image structure to describe the image to
3192 * be written. To do this use memset to set the whole structure to 0 then
3193 * initialize fields describing your image.
3195 * version: must be set to PNG_IMAGE_VERSION
3196 * opaque: must be initialized to NULL
3197 * width: image width in pixels
3198 * height: image height in rows
3199 * format: the format of the data (image and color-map) you wish to write
3200 * flags: set to 0 unless one of the defined flags applies; set
3201 * PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
3202 * values do not correspond to the colors in sRGB.
3203 * colormap_entries: set to the number of entries in the color-map (0 to 256)
3205 PNG_EXPORT(239, int, png_image_write_to_file
, (png_imagep image
,
3206 const char *file
, int convert_to_8bit
, const void *buffer
,
3207 png_int_32 row_stride
, const void *colormap
));
3208 /* Write the image to the named file. */
3210 PNG_EXPORT(240, int, png_image_write_to_stdio
, (png_imagep image
, FILE *file
,
3211 int convert_to_8_bit
, const void *buffer
, png_int_32 row_stride
,
3212 const void *colormap
));
3213 /* Write the image to the given (FILE*). */
3215 /* With both write APIs if image is in one of the linear formats with 16-bit
3216 * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
3217 * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
3218 * encoded PNG file is written.
3220 * With color-mapped data formats the colormap parameter point to a color-map
3221 * with at least image->colormap_entries encoded in the specified format. If
3222 * the format is linear the written PNG color-map will be converted to sRGB
3223 * regardless of the convert_to_8_bit flag.
3225 * With all APIs row_stride is handled as in the read APIs - it is the spacing
3226 * from one row to the next in component sized units (1 or 2 bytes) and if
3227 * negative indicates a bottom-up row layout in the buffer.
3229 * Note that the write API does not support interlacing or sub-8-bit pixels.
3231 #endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */
3232 /*******************************************************************************
3233 * END OF SIMPLIFIED API
3234 ******************************************************************************/
3236 #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
3237 PNG_EXPORT(242, void, png_set_check_for_invalid_index
,
3238 (png_structrp png_ptr
, int allowed
));
3239 # ifdef PNG_GET_PALETTE_MAX_SUPPORTED
3240 PNG_EXPORT(243, int, png_get_palette_max
, (png_const_structp png_ptr
,
3241 png_const_infop info_ptr
));
3243 #endif /* CHECK_FOR_INVALID_INDEX */
3245 /*******************************************************************************
3246 * IMPLEMENTATION OPTIONS
3247 *******************************************************************************
3249 * Support for arbitrary implementation-specific optimizations. The API allows
3250 * particular options to be turned on or off. 'Option' is the number of the
3251 * option and 'onoff' is 0 (off) or non-0 (on). The value returned is given
3252 * by the PNG_OPTION_ defines below.
3254 * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
3255 * are detected at run time, however sometimes it may be impossible
3256 * to do this in user mode, in which case it is necessary to discover
3257 * the capabilities in an OS specific way. Such capabilities are
3258 * listed here when libpng has support for them and must be turned
3259 * ON by the application if present.
3261 * SOFTWARE: sometimes software optimizations actually result in performance
3262 * decrease on some architectures or systems, or with some sets of
3263 * PNG images. 'Software' options allow such optimizations to be
3264 * selected at run time.
3266 #ifdef PNG_SET_OPTION_SUPPORTED
3267 #ifdef PNG_ARM_NEON_API_SUPPORTED
3268 # define PNG_ARM_NEON 0 /* HARDWARE: ARM Neon SIMD instructions supported */
3270 #define PNG_OPTION_NEXT 2 /* Next option - numbers must be even */
3272 /* Return values: NOTE: there are four values and 'off' is *not* zero */
3273 #define PNG_OPTION_UNSET 0 /* Unset - defaults to off */
3274 #define PNG_OPTION_INVALID 1 /* Option number out of range */
3275 #define PNG_OPTION_OFF 2
3276 #define PNG_OPTION_ON 3
3278 PNG_EXPORT(244, int, png_set_option
, (png_structrp png_ptr
, int option
,
3282 /*******************************************************************************
3283 * END OF HARDWARE OPTIONS
3284 ******************************************************************************/
3286 /* Maintainer: Put new public prototypes here ^, in libpng.3, and project
3287 * defs, scripts/pnglibconf.h, and scripts/pnglibconf.h.prebuilt
3290 /* The last ordinal number (this is the *last* one already used; the next
3291 * one to use is one more than this.) Maintainer, remember to add an entry to
3292 * scripts/symbols.def as well.
3294 #ifdef PNG_EXPORT_LAST_ORDINAL
3295 PNG_EXPORT_LAST_ORDINAL(244);
3302 #endif /* PNG_VERSION_INFO_ONLY */
3303 /* Do not put anything past this line */
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