2 /* png.h - header file for PNG reference library
4 * libpng version 1.6.7 - November 14, 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 1.6.7 - November 14, 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]
178 * 1.6.3beta01-11 16 10603 16.so.16.3[.0]
179 * 1.6.3rc01 16 10603 16.so.16.3[.0]
180 * 1.6.3 16 10603 16.so.16.3[.0]
181 * 1.6.4beta01-02 16 10604 16.so.16.4[.0]
182 * 1.6.4rc01 16 10604 16.so.16.4[.0]
183 * 1.6.4 16 10604 16.so.16.4[.0]
184 * 1.6.5 16 10605 16.so.16.5[.0]
185 * 1.6.6 16 10606 16.so.16.6[.0]
186 * 1.6.7beta01-04 16 10607 16.so.16.7[.0]
187 * 1.6.7rc01-02 16 10607 16.so.16.7[.0]
188 * 1.6.7 16 10607 16.so.16.7[.0]
190 * Henceforth the source version will match the shared-library major
191 * and minor numbers; the shared-library major version number will be
192 * used for changes in backward compatibility, as it is intended. The
193 * PNG_LIBPNG_VER macro, which is not used within libpng but is available
194 * for applications, is an unsigned integer of the form xyyzz corresponding
195 * to the source version x.y.z (leading zeros in y and z). Beta versions
196 * were given the previous public release number plus a letter, until
197 * version 1.0.6j; from then on they were given the upcoming public
198 * release number plus "betaNN" or "rcNN".
200 * Binary incompatibility exists only when applications make direct access
201 * to the info_ptr or png_ptr members through png.h, and the compiled
202 * application is loaded with a different version of the library.
204 * DLLNUM will change each time there are forward or backward changes
205 * in binary compatibility (e.g., when a new feature is added).
207 * See libpng-manual.txt or libpng.3 for more information. The PNG
208 * specification is available as a W3C Recommendation and as an ISO
209 * Specification, <http://www.w3.org/TR/2003/REC-PNG-20031110/
213 * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
215 * If you modify libpng you may insert additional notices immediately following
218 * This code is released under the libpng license.
220 * libpng versions 1.2.6, August 15, 2004, through 1.6.7, November 14, 2013, are
221 * Copyright (c) 2004, 2006-2013 Glenn Randers-Pehrson, and are
222 * distributed according to the same disclaimer and license as libpng-1.2.5
223 * with the following individual added to the list of Contributing Authors:
227 * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
228 * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
229 * distributed according to the same disclaimer and license as libpng-1.0.6
230 * with the following individuals added to the list of Contributing Authors:
232 * Simon-Pierre Cadieux
236 * and with the following additions to the disclaimer:
238 * There is no warranty against interference with your enjoyment of the
239 * library or against infringement. There is no warranty that our
240 * efforts or the library will fulfill any of your particular purposes
241 * or needs. This library is provided with all faults, and the entire
242 * risk of satisfactory quality, performance, accuracy, and effort is with
245 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
246 * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson, and are
247 * distributed according to the same disclaimer and license as libpng-0.96,
248 * with the following individuals added to the list of Contributing Authors:
251 * Glenn Randers-Pehrson
254 * libpng versions 0.89, June 1996, through 0.96, May 1997, are
255 * Copyright (c) 1996, 1997 Andreas Dilger
256 * Distributed according to the same disclaimer and license as libpng-0.88,
257 * with the following individuals added to the list of Contributing Authors:
266 * libpng versions 0.5, May 1995, through 0.88, January 1996, are
267 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
269 * For the purposes of this copyright and license, "Contributing Authors"
270 * is defined as the following set of individuals:
278 * The PNG Reference Library is supplied "AS IS". The Contributing Authors
279 * and Group 42, Inc. disclaim all warranties, expressed or implied,
280 * including, without limitation, the warranties of merchantability and of
281 * fitness for any purpose. The Contributing Authors and Group 42, Inc.
282 * assume no liability for direct, indirect, incidental, special, exemplary,
283 * or consequential damages, which may result from the use of the PNG
284 * Reference Library, even if advised of the possibility of such damage.
286 * Permission is hereby granted to use, copy, modify, and distribute this
287 * source code, or portions hereof, for any purpose, without fee, subject
288 * to the following restrictions:
290 * 1. The origin of this source code must not be misrepresented.
292 * 2. Altered versions must be plainly marked as such and must not
293 * be misrepresented as being the original source.
295 * 3. This Copyright notice may not be removed or altered from
296 * any source or altered source distribution.
298 * The Contributing Authors and Group 42, Inc. specifically permit, without
299 * fee, and encourage the use of this source code as a component to
300 * supporting the PNG file format in commercial products. If you use this
301 * source code in a product, acknowledgment is not required but would be
306 * A "png_get_copyright" function is available, for convenient use in "about"
307 * boxes and the like:
309 * printf("%s", png_get_copyright(NULL));
311 * Also, the PNG logo (in PNG format, of course) is supplied in the
312 * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
316 * Libpng is OSI Certified Open Source Software. OSI Certified is a
317 * certification mark of the Open Source Initiative.
321 * The contributing authors would like to thank all those who helped
322 * with testing, bug fixes, and patience. This wouldn't have been
323 * possible without all of you.
325 * Thanks to Frank J. T. Wojcik for helping with the documentation.
329 * Y2K compliance in libpng:
330 * =========================
334 * Since the PNG Development group is an ad-hoc body, we can't make
335 * an official declaration.
337 * This is your unofficial assurance that libpng from version 0.71 and
338 * upward through 1.6.7 are Y2K compliant. It is my belief that
339 * earlier versions were also Y2K compliant.
341 * Libpng only has two year fields. One is a 2-byte unsigned integer
342 * that will hold years up to 65535. The other, which is deprecated,
343 * holds the date in text format, and will hold years up to 9999.
346 * "png_uint_16 year" in png_time_struct.
349 * "char time_buffer[29]" in png_struct. This is no longer used
350 * in libpng-1.6.x and will be removed from libpng-1.7.0.
352 * There are seven time-related functions:
353 * png.c: png_convert_to_rfc_1123_buffer() in png.c
354 * (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
355 * png_convert_to_rfc_1152() in error prior to libpng-0.98)
356 * png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
357 * png_convert_from_time_t() in pngwrite.c
358 * png_get_tIME() in pngget.c
359 * png_handle_tIME() in pngrutil.c, called in pngread.c
360 * png_set_tIME() in pngset.c
361 * png_write_tIME() in pngwutil.c, called in pngwrite.c
363 * All handle dates properly in a Y2K environment. The
364 * png_convert_from_time_t() function calls gmtime() to convert from system
365 * clock time, which returns (year - 1900), which we properly convert to
366 * the full 4-digit year. There is a possibility that libpng applications
367 * are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
368 * function, or that they are incorrectly passing only a 2-digit year
369 * instead of "year - 1900" into the png_convert_from_struct_tm() function,
370 * but this is not under our control. The libpng documentation has always
371 * stated that it works with 4-digit years, and the APIs have been
372 * documented as such.
374 * The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
375 * integer to hold the year, and can hold years as large as 65535.
377 * zlib, upon which libpng depends, is also Y2K compliant. It contains
378 * no date-related code.
380 * Glenn Randers-Pehrson
382 * PNG Development Group
388 /* This is not the place to learn how to use libpng. The file libpng-manual.txt
389 * describes how to use libpng, and the file example.c summarizes it
390 * with some code on which to build. This file is useful for looking
391 * at the actual function definitions and structure components.
393 * If you just need to read a PNG file and don't want to read the documentation
394 * skip to the end of this file and read the section entitled 'simplified API'.
397 /* Version information for png.h - this should match the version in png.c */
398 #define PNG_LIBPNG_VER_STRING "1.6.7"
399 #define PNG_HEADER_VERSION_STRING \
400 " libpng version 1.6.7 - November 14, 2013\n"
402 #define PNG_LIBPNG_VER_SONUM 16
403 #define PNG_LIBPNG_VER_DLLNUM 16
405 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
406 #define PNG_LIBPNG_VER_MAJOR 1
407 #define PNG_LIBPNG_VER_MINOR 6
408 #define PNG_LIBPNG_VER_RELEASE 7
410 /* This should match the numeric part of the final component of
411 * PNG_LIBPNG_VER_STRING, omitting any leading zero:
414 #define PNG_LIBPNG_VER_BUILD 0
417 #define PNG_LIBPNG_BUILD_ALPHA 1
418 #define PNG_LIBPNG_BUILD_BETA 2
419 #define PNG_LIBPNG_BUILD_RC 3
420 #define PNG_LIBPNG_BUILD_STABLE 4
421 #define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
423 /* Release-Specific Flags */
424 #define PNG_LIBPNG_BUILD_PATCH 8 /* Can be OR'ed with
425 PNG_LIBPNG_BUILD_STABLE only */
426 #define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
427 PNG_LIBPNG_BUILD_SPECIAL */
428 #define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
429 PNG_LIBPNG_BUILD_PRIVATE */
431 #define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
433 /* Careful here. At one time, Guy wanted to use 082, but that would be octal.
434 * We must not include leading zeros.
435 * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
436 * version 1.0.0 was mis-numbered 100 instead of 10000). From
437 * version 1.0.1 it's xxyyzz, where x=major, y=minor, z=release
439 #define PNG_LIBPNG_VER 10607 /* 1.6.7 */
441 /* Library configuration: these options cannot be changed after
442 * the library has been built.
445 /* If pnglibconf.h is missing, you can
446 * copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
448 # include "pnglibconf.h"
451 #ifndef PNG_VERSION_INFO_ONLY
452 /* Machine specific configuration. */
453 # include "pngconf.h"
457 * Added at libpng-1.2.8
459 * Ref MSDN: Private as priority over Special
460 * VS_FF_PRIVATEBUILD File *was not* built using standard release
461 * procedures. If this value is given, the StringFileInfo block must
462 * contain a PrivateBuild string.
464 * VS_FF_SPECIALBUILD File *was* built by the original company using
465 * standard release procedures but is a variation of the standard
466 * file of the same version number. If this value is given, the
467 * StringFileInfo block must contain a SpecialBuild string.
470 #ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
471 # define PNG_LIBPNG_BUILD_TYPE \
472 (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
474 # ifdef PNG_LIBPNG_SPECIALBUILD
475 # define PNG_LIBPNG_BUILD_TYPE \
476 (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
478 # define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
482 #ifndef PNG_VERSION_INFO_ONLY
484 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
487 #endif /* __cplusplus */
489 /* Version information for C files, stored in png.c. This had better match
492 #define png_libpng_ver png_get_header_ver(NULL)
494 /* This file is arranged in several sections:
496 * 1. Any configuration options that can be specified by for the application
497 * code when it is built. (Build time configuration is in pnglibconf.h)
498 * 2. Type definitions (base types are defined in pngconf.h), structure
500 * 3. Exported library functions.
503 * The library source code has additional files (principally pngpriv.h) that
504 * allow configuration of the library.
506 /* Section 1: run time configuration
507 * See pnglibconf.h for build time configuration
509 * Run time configuration allows the application to choose between
510 * implementations of certain arithmetic APIs. The default is set
511 * at build time and recorded in pnglibconf.h, but it is safe to
512 * override these (and only these) settings. Note that this won't
513 * change what the library does, only application code, and the
514 * settings can (and probably should) be made on a per-file basis
515 * by setting the #defines before including png.h
517 * Use macros to read integers from PNG data or use the exported
519 * PNG_USE_READ_MACROS: use the macros (see below) Note that
520 * the macros evaluate their argument multiple times.
521 * PNG_NO_USE_READ_MACROS: call the relevant library function.
523 * Use the alternative algorithm for compositing alpha samples that
524 * does not use division?
525 * PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
527 * PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
529 * How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
531 * PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
532 * APIs to png_warning.
533 * Otherwise the calls are mapped to png_error.
536 /* Section 2: type definitions, including structures and compile time
538 * See pngconf.h for base types that vary by machine/system
541 /* This triggers a compiler error in png.c, if png.c and png.h
542 * do not agree upon the version number.
544 typedef char* png_libpng_version_1_6_7;
546 /* Basic control structions. Read libpng-manual.txt or libpng.3 for more info.
548 * png_struct is the cache of information used while reading or writing a single
549 * PNG file. One of these is always required, although the simplified API
550 * (below) hides the creation and destruction of it.
552 typedef struct png_struct_def png_struct;
553 typedef const png_struct * png_const_structp;
554 typedef png_struct * png_structp;
555 typedef png_struct * * png_structpp;
557 /* png_info contains information read from or to be written to a PNG file. One
558 * or more of these must exist while reading or creating a PNG file. The
559 * information is not used by libpng during read but is used to control what
560 * gets written when a PNG file is created. "png_get_" function calls read
561 * information during read and "png_set_" functions calls write information
562 * when creating a PNG.
563 * been moved into a separate header file that is not accessible to
564 * applications. Read libpng-manual.txt or libpng.3 for more info.
566 typedef struct png_info_def png_info;
567 typedef png_info * png_infop;
568 typedef const png_info * png_const_infop;
569 typedef png_info * * png_infopp;
571 /* Types with names ending 'p' are pointer types. The corresponding types with
572 * names ending 'rp' are identical pointer types except that the pointer is
573 * marked 'restrict', which means that it is the only pointer to the object
574 * passed to the function. Applications should not use the 'restrict' types;
575 * it is always valid to pass 'p' to a pointer with a function argument of the
576 * corresponding 'rp' type. Different compilers have different rules with
577 * regard to type matching in the presence of 'restrict'. For backward
578 * compatibility libpng callbacks never have 'restrict' in their parameters and,
579 * consequentially, writing portable application code is extremely difficult if
580 * an attempt is made to use 'restrict'.
582 typedef png_struct * PNG_RESTRICT png_structrp;
583 typedef const png_struct * PNG_RESTRICT png_const_structrp;
584 typedef png_info * PNG_RESTRICT png_inforp;
585 typedef const png_info * PNG_RESTRICT png_const_inforp;
587 /* Three color definitions. The order of the red, green, and blue, (and the
588 * exact size) is not important, although the size of the fields need to
589 * be png_byte or png_uint_16 (as defined below).
591 typedef struct png_color_struct
597 typedef png_color * png_colorp;
598 typedef const png_color * png_const_colorp;
599 typedef png_color * * png_colorpp;
601 typedef struct png_color_16_struct
603 png_byte index; /* used for palette files */
604 png_uint_16 red; /* for use in red green blue files */
607 png_uint_16 gray; /* for use in grayscale files */
609 typedef png_color_16 * png_color_16p;
610 typedef const png_color_16 * png_const_color_16p;
611 typedef png_color_16 * * png_color_16pp;
613 typedef struct png_color_8_struct
615 png_byte red; /* for use in red green blue files */
618 png_byte gray; /* for use in grayscale files */
619 png_byte alpha; /* for alpha channel files */
621 typedef png_color_8 * png_color_8p;
622 typedef const png_color_8 * png_const_color_8p;
623 typedef png_color_8 * * png_color_8pp;
626 * The following two structures are used for the in-core representation
629 typedef struct png_sPLT_entry_struct
635 png_uint_16 frequency;
637 typedef png_sPLT_entry * png_sPLT_entryp;
638 typedef const png_sPLT_entry * png_const_sPLT_entryp;
639 typedef png_sPLT_entry * * png_sPLT_entrypp;
641 /* When the depth of the sPLT palette is 8 bits, the color and alpha samples
642 * occupy the LSB of their respective members, and the MSB of each member
643 * is zero-filled. The frequency member always occupies the full 16 bits.
646 typedef struct png_sPLT_struct
648 png_charp name; /* palette name */
649 png_byte depth; /* depth of palette samples */
650 png_sPLT_entryp entries; /* palette entries */
651 png_int_32 nentries; /* number of palette entries */
653 typedef png_sPLT_t * png_sPLT_tp;
654 typedef const png_sPLT_t * png_const_sPLT_tp;
655 typedef png_sPLT_t * * png_sPLT_tpp;
657 #ifdef PNG_TEXT_SUPPORTED
658 /* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
659 * and whether that contents is compressed or not. The "key" field
660 * points to a regular zero-terminated C string. The "text" fields can be a
661 * regular C string, an empty string, or a NULL pointer.
662 * However, the structure returned by png_get_text() will always contain
663 * the "text" field as a regular zero-terminated C string (possibly
664 * empty), never a NULL pointer, so it can be safely used in printf() and
665 * other string-handling functions. Note that the "itxt_length", "lang", and
666 * "lang_key" members of the structure only exist when the library is built
667 * with iTXt chunk support. Prior to libpng-1.4.0 the library was built by
668 * default without iTXt support. Also note that when iTXt *is* supported,
669 * the "lang" and "lang_key" fields contain NULL pointers when the
670 * "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
671 * PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
672 * same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
673 * which is always 0 or 1, or its "compression method" which is always 0.
675 typedef struct png_text_struct
677 int compression; /* compression value:
682 png_charp key; /* keyword, 1-79 character description of "text" */
683 png_charp text; /* comment, may be an empty string (ie "")
685 png_size_t text_length; /* length of the text string */
686 png_size_t itxt_length; /* length of the itxt string */
687 png_charp lang; /* language code, 0-79 characters
689 png_charp lang_key; /* keyword translated UTF-8 string, 0 or more
690 chars or a NULL pointer */
692 typedef png_text * png_textp;
693 typedef const png_text * png_const_textp;
694 typedef png_text * * png_textpp;
697 /* Supported compression types for text in PNG files (tEXt, and zTXt).
698 * The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
699 #define PNG_TEXT_COMPRESSION_NONE_WR -3
700 #define PNG_TEXT_COMPRESSION_zTXt_WR -2
701 #define PNG_TEXT_COMPRESSION_NONE -1
702 #define PNG_TEXT_COMPRESSION_zTXt 0
703 #define PNG_ITXT_COMPRESSION_NONE 1
704 #define PNG_ITXT_COMPRESSION_zTXt 2
705 #define PNG_TEXT_COMPRESSION_LAST 3 /* Not a valid value */
707 /* png_time is a way to hold the time in an machine independent way.
708 * Two conversions are provided, both from time_t and struct tm. There
709 * is no portable way to convert to either of these structures, as far
710 * as I know. If you know of a portable way, send it to me. As a side
711 * note - PNG has always been Year 2000 compliant!
713 typedef struct png_time_struct
715 png_uint_16 year; /* full year, as in, 1995 */
716 png_byte month; /* month of year, 1 - 12 */
717 png_byte day; /* day of month, 1 - 31 */
718 png_byte hour; /* hour of day, 0 - 23 */
719 png_byte minute; /* minute of hour, 0 - 59 */
720 png_byte second; /* second of minute, 0 - 60 (for leap seconds) */
722 typedef png_time * png_timep;
723 typedef const png_time * png_const_timep;
724 typedef png_time * * png_timepp;
726 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
727 defined(PNG_USER_CHUNKS_SUPPORTED)
728 /* png_unknown_chunk is a structure to hold queued chunks for which there is
729 * no specific support. The idea is that we can use this to queue
730 * up private chunks for output even though the library doesn't actually
731 * know about their semantics.
733 * The data in the structure is set by libpng on read and used on write.
735 typedef struct png_unknown_chunk_t
737 png_byte name[5]; /* Textual chunk name with '\0' terminator */
738 png_byte *data; /* Data, should not be modified on read! */
741 /* On write 'location' must be set using the flag values listed below.
742 * Notice that on read it is set by libpng however the values stored have
743 * more bits set than are listed below. Always treat the value as a
744 * bitmask. On write set only one bit - setting multiple bits may cause the
745 * chunk to be written in multiple places.
747 png_byte location; /* mode of operation at read time */
751 typedef png_unknown_chunk * png_unknown_chunkp;
752 typedef const png_unknown_chunk * png_const_unknown_chunkp;
753 typedef png_unknown_chunk * * png_unknown_chunkpp;
756 /* Flag values for the unknown chunk location byte. */
757 #define PNG_HAVE_IHDR 0x01
758 #define PNG_HAVE_PLTE 0x02
759 #define PNG_AFTER_IDAT 0x08
761 /* Maximum positive integer used in PNG is (2^31)-1 */
762 #define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
763 #define PNG_UINT_32_MAX ((png_uint_32)(-1))
764 #define PNG_SIZE_MAX ((png_size_t)(-1))
766 /* These are constants for fixed point values encoded in the
767 * PNG specification manner (x100000)
769 #define PNG_FP_1 100000
770 #define PNG_FP_HALF 50000
771 #define PNG_FP_MAX ((png_fixed_point)0x7fffffffL)
772 #define PNG_FP_MIN (-PNG_FP_MAX)
774 /* These describe the color_type field in png_info. */
775 /* color type masks */
776 #define PNG_COLOR_MASK_PALETTE 1
777 #define PNG_COLOR_MASK_COLOR 2
778 #define PNG_COLOR_MASK_ALPHA 4
780 /* color types. Note that not all combinations are legal */
781 #define PNG_COLOR_TYPE_GRAY 0
782 #define PNG_COLOR_TYPE_PALETTE (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
783 #define PNG_COLOR_TYPE_RGB (PNG_COLOR_MASK_COLOR)
784 #define PNG_COLOR_TYPE_RGB_ALPHA (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
785 #define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
787 #define PNG_COLOR_TYPE_RGBA PNG_COLOR_TYPE_RGB_ALPHA
788 #define PNG_COLOR_TYPE_GA PNG_COLOR_TYPE_GRAY_ALPHA
790 /* This is for compression type. PNG 1.0-1.2 only define the single type. */
791 #define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
792 #define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE
794 /* This is for filter type. PNG 1.0-1.2 only define the single type. */
795 #define PNG_FILTER_TYPE_BASE 0 /* Single row per-byte filtering */
796 #define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
797 #define PNG_FILTER_TYPE_DEFAULT PNG_FILTER_TYPE_BASE
799 /* These are for the interlacing type. These values should NOT be changed. */
800 #define PNG_INTERLACE_NONE 0 /* Non-interlaced image */
801 #define PNG_INTERLACE_ADAM7 1 /* Adam7 interlacing */
802 #define PNG_INTERLACE_LAST 2 /* Not a valid value */
804 /* These are for the oFFs chunk. These values should NOT be changed. */
805 #define PNG_OFFSET_PIXEL 0 /* Offset in pixels */
806 #define PNG_OFFSET_MICROMETER 1 /* Offset in micrometers (1/10^6 meter) */
807 #define PNG_OFFSET_LAST 2 /* Not a valid value */
809 /* These are for the pCAL chunk. These values should NOT be changed. */
810 #define PNG_EQUATION_LINEAR 0 /* Linear transformation */
811 #define PNG_EQUATION_BASE_E 1 /* Exponential base e transform */
812 #define PNG_EQUATION_ARBITRARY 2 /* Arbitrary base exponential transform */
813 #define PNG_EQUATION_HYPERBOLIC 3 /* Hyperbolic sine transformation */
814 #define PNG_EQUATION_LAST 4 /* Not a valid value */
816 /* These are for the sCAL chunk. These values should NOT be changed. */
817 #define PNG_SCALE_UNKNOWN 0 /* unknown unit (image scale) */
818 #define PNG_SCALE_METER 1 /* meters per pixel */
819 #define PNG_SCALE_RADIAN 2 /* radians per pixel */
820 #define PNG_SCALE_LAST 3 /* Not a valid value */
822 /* These are for the pHYs chunk. These values should NOT be changed. */
823 #define PNG_RESOLUTION_UNKNOWN 0 /* pixels/unknown unit (aspect ratio) */
824 #define PNG_RESOLUTION_METER 1 /* pixels/meter */
825 #define PNG_RESOLUTION_LAST 2 /* Not a valid value */
827 /* These are for the sRGB chunk. These values should NOT be changed. */
828 #define PNG_sRGB_INTENT_PERCEPTUAL 0
829 #define PNG_sRGB_INTENT_RELATIVE 1
830 #define PNG_sRGB_INTENT_SATURATION 2
831 #define PNG_sRGB_INTENT_ABSOLUTE 3
832 #define PNG_sRGB_INTENT_LAST 4 /* Not a valid value */
834 /* This is for text chunks */
835 #define PNG_KEYWORD_MAX_LENGTH 79
837 /* Maximum number of entries in PLTE/sPLT/tRNS arrays */
838 #define PNG_MAX_PALETTE_LENGTH 256
840 /* These determine if an ancillary chunk's data has been successfully read
841 * from the PNG header, or if the application has filled in the corresponding
842 * data in the info_struct to be written into the output file. The values
843 * of the PNG_INFO_<chunk> defines should NOT be changed.
845 #define PNG_INFO_gAMA 0x0001
846 #define PNG_INFO_sBIT 0x0002
847 #define PNG_INFO_cHRM 0x0004
848 #define PNG_INFO_PLTE 0x0008
849 #define PNG_INFO_tRNS 0x0010
850 #define PNG_INFO_bKGD 0x0020
851 #define PNG_INFO_hIST 0x0040
852 #define PNG_INFO_pHYs 0x0080
853 #define PNG_INFO_oFFs 0x0100
854 #define PNG_INFO_tIME 0x0200
855 #define PNG_INFO_pCAL 0x0400
856 #define PNG_INFO_sRGB 0x0800 /* GR-P, 0.96a */
857 #define PNG_INFO_iCCP 0x1000 /* ESR, 1.0.6 */
858 #define PNG_INFO_sPLT 0x2000 /* ESR, 1.0.6 */
859 #define PNG_INFO_sCAL 0x4000 /* ESR, 1.0.6 */
860 #define PNG_INFO_IDAT 0x8000 /* ESR, 1.0.6 */
862 /* This is used for the transformation routines, as some of them
863 * change these values for the row. It also should enable using
864 * the routines for other purposes.
866 typedef struct png_row_info_struct
868 png_uint_32 width; /* width of row */
869 png_size_t rowbytes; /* number of bytes in row */
870 png_byte color_type; /* color type of row */
871 png_byte bit_depth; /* bit depth of row */
872 png_byte channels; /* number of channels (1, 2, 3, or 4) */
873 png_byte pixel_depth; /* bits per pixel (depth * channels) */
876 typedef png_row_info * png_row_infop;
877 typedef png_row_info * * png_row_infopp;
879 /* These are the function types for the I/O functions and for the functions
880 * that allow the user to override the default I/O functions with his or her
881 * own. The png_error_ptr type should match that of user-supplied warning
882 * and error functions, while the png_rw_ptr type should match that of the
883 * user read/write data functions. Note that the 'write' function must not
884 * modify the buffer it is passed. The 'read' function, on the other hand, is
885 * expected to return the read data in the buffer.
887 typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
888 typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
889 typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
890 typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
892 typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
895 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
896 typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
897 typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
899 /* The following callback receives png_uint_32 row_number, int pass for the
900 * png_bytep data of the row. When transforming an interlaced image the
901 * row number is the row number within the sub-image of the interlace pass, so
902 * the value will increase to the height of the sub-image (not the full image)
903 * then reset to 0 for the next pass.
905 * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
906 * find the output pixel (x,y) given an interlaced sub-image pixel
907 * (row,col,pass). (See below for these macros.)
909 typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
913 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
914 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
915 typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
919 #ifdef PNG_USER_CHUNKS_SUPPORTED
920 typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
921 png_unknown_chunkp));
923 #ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
924 /* not used anywhere */
925 /* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
928 #ifdef PNG_SETJMP_SUPPORTED
929 /* This must match the function definition in <setjmp.h>, and the application
930 * must include this before png.h to obtain the definition of jmp_buf. The
931 * function is required to be PNG_NORETURN, but this is not checked. If the
932 * function does return the application will crash via an abort() or similar
935 * If you get a warning here while building the library you may need to make
936 * changes to ensure that pnglibconf.h records the calling convention used by
937 * your compiler. This may be very difficult - try using a different compiler
938 * to build the library!
940 PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
943 /* Transform masks for the high-level interface */
944 #define PNG_TRANSFORM_IDENTITY 0x0000 /* read and write */
945 #define PNG_TRANSFORM_STRIP_16 0x0001 /* read only */
946 #define PNG_TRANSFORM_STRIP_ALPHA 0x0002 /* read only */
947 #define PNG_TRANSFORM_PACKING 0x0004 /* read and write */
948 #define PNG_TRANSFORM_PACKSWAP 0x0008 /* read and write */
949 #define PNG_TRANSFORM_EXPAND 0x0010 /* read only */
950 #define PNG_TRANSFORM_INVERT_MONO 0x0020 /* read and write */
951 #define PNG_TRANSFORM_SHIFT 0x0040 /* read and write */
952 #define PNG_TRANSFORM_BGR 0x0080 /* read and write */
953 #define PNG_TRANSFORM_SWAP_ALPHA 0x0100 /* read and write */
954 #define PNG_TRANSFORM_SWAP_ENDIAN 0x0200 /* read and write */
955 #define PNG_TRANSFORM_INVERT_ALPHA 0x0400 /* read and write */
956 #define PNG_TRANSFORM_STRIP_FILLER 0x0800 /* write only */
957 /* Added to libpng-1.2.34 */
958 #define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
959 #define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
960 /* Added to libpng-1.4.0 */
961 #define PNG_TRANSFORM_GRAY_TO_RGB 0x2000 /* read only */
962 /* Added to libpng-1.5.4 */
963 #define PNG_TRANSFORM_EXPAND_16 0x4000 /* read only */
964 #define PNG_TRANSFORM_SCALE_16 0x8000 /* read only */
966 /* Flags for MNG supported features */
967 #define PNG_FLAG_MNG_EMPTY_PLTE 0x01
968 #define PNG_FLAG_MNG_FILTER_64 0x04
969 #define PNG_ALL_MNG_FEATURES 0x05
971 /* NOTE: prior to 1.5 these functions had no 'API' style declaration,
972 * this allowed the zlib default functions to be used on Windows
973 * platforms. In 1.5 the zlib default malloc (which just calls malloc and
974 * ignores the first argument) should be completely compatible with the
977 typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
979 typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
981 /* Section 3: exported functions
982 * Here are the function definitions most commonly used. This is not
983 * the place to find out how to use libpng. See libpng-manual.txt for the
984 * full explanation, see example.c for the summary. This just provides
985 * a simple one line description of the use of each function.
987 * The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
988 * pngconf.h and in the *.dfn files in the scripts directory.
990 * PNG_EXPORT(ordinal, type, name, (args));
992 * ordinal: ordinal that is used while building
993 * *.def files. The ordinal value is only
994 * relevant when preprocessing png.h with
995 * the *.dfn files for building symbol table
996 * entries, and are removed by pngconf.h.
997 * type: return type of the function
998 * name: function name
999 * args: function arguments, with types
1001 * When we wish to append attributes to a function prototype we use
1002 * the PNG_EXPORTA() macro instead.
1004 * PNG_EXPORTA(ordinal, type, name, (args), attributes);
1006 * ordinal, type, name, and args: same as in PNG_EXPORT().
1007 * attributes: function attributes
1010 /* Returns the version number of the library */
1011 PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
1013 /* Tell lib we have already handled the first <num_bytes> magic bytes.
1014 * Handling more than 8 bytes from the beginning of the file is an error.
1016 PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
1018 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
1019 * PNG file. Returns zero if the supplied bytes match the 8-byte PNG
1020 * signature, and non-zero otherwise. Having num_to_check == 0 or
1021 * start > 7 will always fail (ie return non-zero).
1023 PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
1024 png_size_t num_to_check));
1026 /* Simple signature checking function. This is the same as calling
1027 * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
1029 #define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
1031 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
1032 PNG_EXPORTA(4, png_structp, png_create_read_struct,
1033 (png_const_charp user_png_ver, png_voidp error_ptr,
1034 png_error_ptr error_fn, png_error_ptr warn_fn),
1037 /* Allocate and initialize png_ptr struct for writing, and any other memory */
1038 PNG_EXPORTA(5, png_structp, png_create_write_struct,
1039 (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1040 png_error_ptr warn_fn),
1043 PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
1044 (png_const_structrp png_ptr));
1046 PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
1049 /* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
1052 #ifdef PNG_SETJMP_SUPPORTED
1053 /* This function returns the jmp_buf built in to *png_ptr. It must be
1054 * supplied with an appropriate 'longjmp' function to use on that jmp_buf
1055 * unless the default error function is overridden in which case NULL is
1056 * acceptable. The size of the jmp_buf is checked against the actual size
1057 * allocated by the library - the call will return NULL on a mismatch
1058 * indicating an ABI mismatch.
1060 PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
1061 png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
1062 # define png_jmpbuf(png_ptr) \
1063 (*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
1065 # define png_jmpbuf(png_ptr) \
1066 (LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
1068 /* This function should be used by libpng applications in place of
1069 * longjmp(png_ptr->jmpbuf, val). If longjmp_fn() has been set, it
1070 * will use it; otherwise it will call PNG_ABORT(). This function was
1071 * added in libpng-1.5.0.
1073 PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
1076 #ifdef PNG_READ_SUPPORTED
1077 /* Reset the compression stream */
1078 PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
1081 /* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
1082 #ifdef PNG_USER_MEM_SUPPORTED
1083 PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
1084 (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1085 png_error_ptr warn_fn,
1086 png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1088 PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
1089 (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
1090 png_error_ptr warn_fn,
1091 png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
1095 /* Write the PNG file signature. */
1096 PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
1098 /* Write a PNG chunk - size, type, (optional) data, CRC. */
1099 PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
1100 chunk_name, png_const_bytep data, png_size_t length));
1102 /* Write the start of a PNG chunk - length and chunk name. */
1103 PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
1104 png_const_bytep chunk_name, png_uint_32 length));
1106 /* Write the data of a PNG chunk started with png_write_chunk_start(). */
1107 PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
1108 png_const_bytep data, png_size_t length));
1110 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
1111 PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
1113 /* Allocate and initialize the info structure */
1114 PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
1117 /* DEPRECATED: this function allowed init structures to be created using the
1118 * default allocation method (typically malloc). Use is deprecated in 1.6.0 and
1119 * the API will be removed in the future.
1121 PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
1122 png_size_t png_info_struct_size), PNG_DEPRECATED);
1124 /* Writes all the PNG information before the image. */
1125 PNG_EXPORT(20, void, png_write_info_before_PLTE,
1126 (png_structrp png_ptr, png_const_inforp info_ptr));
1127 PNG_EXPORT(21, void, png_write_info,
1128 (png_structrp png_ptr, png_const_inforp info_ptr));
1130 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1131 /* Read the information before the actual image data. */
1132 PNG_EXPORT(22, void, png_read_info,
1133 (png_structrp png_ptr, png_inforp info_ptr));
1136 #ifdef PNG_TIME_RFC1123_SUPPORTED
1137 /* Convert to a US string format: there is no localization support in this
1138 * routine. The original implementation used a 29 character buffer in
1139 * png_struct, this will be removed in future versions.
1141 #if PNG_LIBPNG_VER < 10700
1142 /* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
1143 PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
1144 png_const_timep ptime),PNG_DEPRECATED);
1146 PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
1147 png_const_timep ptime));
1150 #ifdef PNG_CONVERT_tIME_SUPPORTED
1151 /* Convert from a struct tm to png_time */
1152 PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
1153 const struct tm * ttime));
1155 /* Convert from time_t to png_time. Uses gmtime() */
1156 PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
1157 #endif /* PNG_CONVERT_tIME_SUPPORTED */
1159 #ifdef PNG_READ_EXPAND_SUPPORTED
1160 /* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
1161 PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
1162 PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
1163 PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
1164 PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
1167 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1168 /* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
1169 * of a tRNS chunk if present.
1171 PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
1174 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
1175 /* Use blue, green, red order for pixels. */
1176 PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
1179 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1180 /* Expand the grayscale to 24-bit RGB if necessary. */
1181 PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
1184 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
1185 /* Reduce RGB to grayscale. */
1186 #define PNG_ERROR_ACTION_NONE 1
1187 #define PNG_ERROR_ACTION_WARN 2
1188 #define PNG_ERROR_ACTION_ERROR 3
1189 #define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
1191 PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
1192 int error_action, double red, double green))
1193 PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
1194 int error_action, png_fixed_point red, png_fixed_point green))
1196 PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
1200 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
1201 PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
1202 png_colorp palette));
1205 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1206 /* How the alpha channel is interpreted - this affects how the color channels of
1207 * a PNG file are returned when an alpha channel, or tRNS chunk in a palette
1210 * This has no effect on the way pixels are written into a PNG output
1211 * datastream. The color samples in a PNG datastream are never premultiplied
1212 * with the alpha samples.
1214 * The default is to return data according to the PNG specification: the alpha
1215 * channel is a linear measure of the contribution of the pixel to the
1216 * corresponding composited pixel. The gamma encoded color channels must be
1217 * scaled according to the contribution and to do this it is necessary to undo
1218 * the encoding, scale the color values, perform the composition and reencode
1219 * the values. This is the 'PNG' mode.
1221 * The alternative is to 'associate' the alpha with the color information by
1222 * storing color channel values that have been scaled by the alpha. The
1223 * advantage is that the color channels can be resampled (the image can be
1224 * scaled) in this form. The disadvantage is that normal practice is to store
1225 * linear, not (gamma) encoded, values and this requires 16-bit channels for
1226 * still images rather than the 8-bit channels that are just about sufficient if
1227 * gamma encoding is used. In addition all non-transparent pixel values,
1228 * including completely opaque ones, must be gamma encoded to produce the final
1229 * image. This is the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' mode (the
1230 * latter being the two common names for associated alpha color channels.)
1232 * Since it is not necessary to perform arithmetic on opaque color values so
1233 * long as they are not to be resampled and are in the final color space it is
1234 * possible to optimize the handling of alpha by storing the opaque pixels in
1235 * the PNG format (adjusted for the output color space) while storing partially
1236 * opaque pixels in the standard, linear, format. The accuracy required for
1237 * standard alpha composition is relatively low, because the pixels are
1238 * isolated, therefore typically the accuracy loss in storing 8-bit linear
1239 * values is acceptable. (This is not true if the alpha channel is used to
1240 * simulate transparency over large areas - use 16 bits or the PNG mode in
1241 * this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
1242 * treated as opaque only if the alpha value is equal to the maximum value.
1244 * The final choice is to gamma encode the alpha channel as well. This is
1245 * broken because, in practice, no implementation that uses this choice
1246 * correctly undoes the encoding before handling alpha composition. Use this
1247 * choice only if other serious errors in the software or hardware you use
1248 * mandate it; the typical serious error is for dark halos to appear around
1249 * opaque areas of the composited PNG image because of arithmetic overflow.
1251 * The API function png_set_alpha_mode specifies which of these choices to use
1252 * with an enumerated 'mode' value and the gamma of the required output:
1254 #define PNG_ALPHA_PNG 0 /* according to the PNG standard */
1255 #define PNG_ALPHA_STANDARD 1 /* according to Porter/Duff */
1256 #define PNG_ALPHA_ASSOCIATED 1 /* as above; this is the normal practice */
1257 #define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
1258 #define PNG_ALPHA_OPTIMIZED 2 /* 'PNG' for opaque pixels, else 'STANDARD' */
1259 #define PNG_ALPHA_BROKEN 3 /* the alpha channel is gamma encoded */
1261 PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
1262 double output_gamma))
1263 PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
1264 int mode, png_fixed_point output_gamma))
1267 #if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1268 /* The output_gamma value is a screen gamma in libpng terminology: it expresses
1269 * how to decode the output values, not how they are encoded. The values used
1270 * correspond to the normal numbers used to describe the overall gamma of a
1271 * computer display system; for example 2.2 for an sRGB conformant system. The
1272 * values are scaled by 100000 in the _fixed version of the API (so 220000 for
1275 * The inverse of the value is always used to provide a default for the PNG file
1276 * encoding if it has no gAMA chunk and if png_set_gamma() has not been called
1277 * to override the PNG gamma information.
1279 * When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
1280 * opaque pixels however pixels with lower alpha values are not encoded,
1281 * regardless of the output gamma setting.
1283 * When the standard Porter Duff handling is requested with mode 1 the output
1284 * encoding is set to be linear and the output_gamma value is only relevant
1285 * as a default for input data that has no gamma information. The linear output
1286 * encoding will be overridden if png_set_gamma() is called - the results may be
1287 * highly unexpected!
1289 * The following numbers are derived from the sRGB standard and the research
1290 * behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
1291 * 0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
1292 * correction required to take account of any differences in the color
1293 * environment of the original scene and the intended display environment; the
1294 * value expresses how to *decode* the image for display, not how the original
1295 * data was *encoded*.
1297 * sRGB provides a peg for the PNG standard by defining a viewing environment.
1298 * sRGB itself, and earlier TV standards, actually use a more complex transform
1299 * (a linear portion then a gamma 2.4 power law) than PNG can express. (PNG is
1300 * limited to simple power laws.) By saying that an image for direct display on
1301 * an sRGB conformant system should be stored with a gAMA chunk value of 45455
1302 * (11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
1303 * makes it possible to derive values for other display systems and
1306 * The Mac value is deduced from the sRGB based on an assumption that the actual
1307 * extra viewing correction used in early Mac display systems was implemented as
1308 * a power 1.45 lookup table.
1310 * Any system where a programmable lookup table is used or where the behavior of
1311 * the final display device characteristics can be changed requires system
1312 * specific code to obtain the current characteristic. However this can be
1313 * difficult and most PNG gamma correction only requires an approximate value.
1315 * By default, if png_set_alpha_mode() is not called, libpng assumes that all
1316 * values are unencoded, linear, values and that the output device also has a
1317 * linear characteristic. This is only very rarely correct - it is invariably
1318 * better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
1319 * default if you don't know what the right answer is!
1321 * The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
1322 * 10.6) which used a correction table to implement a somewhat lower gamma on an
1323 * otherwise sRGB system.
1325 * Both these values are reserved (not simple gamma values) in order to allow
1326 * more precise correction internally in the future.
1328 * NOTE: the following values can be passed to either the fixed or floating
1329 * point APIs, but the floating point API will also accept floating point
1332 #define PNG_DEFAULT_sRGB -1 /* sRGB gamma and color space */
1333 #define PNG_GAMMA_MAC_18 -2 /* Old Mac '1.8' gamma and color space */
1334 #define PNG_GAMMA_sRGB 220000 /* Television standards--matches sRGB gamma */
1335 #define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
1338 /* The following are examples of calls to png_set_alpha_mode to achieve the
1339 * required overall gamma correction and, where necessary, alpha
1340 * premultiplication.
1342 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1343 * This is the default libpng handling of the alpha channel - it is not
1344 * pre-multiplied into the color components. In addition the call states
1345 * that the output is for a sRGB system and causes all PNG files without gAMA
1346 * chunks to be assumed to be encoded using sRGB.
1348 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1349 * In this case the output is assumed to be something like an sRGB conformant
1350 * display preceeded by a power-law lookup table of power 1.45. This is how
1351 * early Mac systems behaved.
1353 * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
1354 * This is the classic Jim Blinn approach and will work in academic
1355 * environments where everything is done by the book. It has the shortcoming
1356 * of assuming that input PNG data with no gamma information is linear - this
1357 * is unlikely to be correct unless the PNG files where generated locally.
1358 * Most of the time the output precision will be so low as to show
1359 * significant banding in dark areas of the image.
1361 * png_set_expand_16(pp);
1362 * png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
1363 * This is a somewhat more realistic Jim Blinn inspired approach. PNG files
1364 * are assumed to have the sRGB encoding if not marked with a gamma value and
1365 * the output is always 16 bits per component. This permits accurate scaling
1366 * and processing of the data. If you know that your input PNG files were
1367 * generated locally you might need to replace PNG_DEFAULT_sRGB with the
1368 * correct value for your system.
1370 * png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
1371 * If you just need to composite the PNG image onto an existing background
1372 * and if you control the code that does this you can use the optimization
1373 * setting. In this case you just copy completely opaque pixels to the
1374 * output. For pixels that are not completely transparent (you just skip
1375 * those) you do the composition math using png_composite or png_composite_16
1376 * below then encode the resultant 8-bit or 16-bit values to match the output
1380 * If neither the PNG nor the standard linear encoding work for you because
1381 * of the software or hardware you use then you have a big problem. The PNG
1382 * case will probably result in halos around the image. The linear encoding
1383 * will probably result in a washed out, too bright, image (it's actually too
1384 * contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
1385 * substantially reduce the halos. Alternatively try:
1387 * png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
1388 * This option will also reduce the halos, but there will be slight dark
1389 * halos round the opaque parts of the image where the background is light.
1390 * In the OPTIMIZED mode the halos will be light halos where the background
1391 * is dark. Take your pick - the halos are unavoidable unless you can get
1392 * your hardware/software fixed! (The OPTIMIZED approach is slightly
1395 * When the default gamma of PNG files doesn't match the output gamma.
1396 * If you have PNG files with no gamma information png_set_alpha_mode allows
1397 * you to provide a default gamma, but it also sets the ouput gamma to the
1398 * matching value. If you know your PNG files have a gamma that doesn't
1399 * match the output you can take advantage of the fact that
1400 * png_set_alpha_mode always sets the output gamma but only sets the PNG
1401 * default if it is not already set:
1403 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
1404 * png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
1405 * The first call sets both the default and the output gamma values, the
1406 * second call overrides the output gamma without changing the default. This
1407 * is easier than achieving the same effect with png_set_gamma. You must use
1408 * PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
1409 * fire if more than one call to png_set_alpha_mode and png_set_background is
1410 * made in the same read operation, however multiple calls with PNG_ALPHA_PNG
1414 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1415 PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
1418 #if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
1419 defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
1420 PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
1423 #if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
1424 defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
1425 PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
1428 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
1429 /* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
1430 PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
1432 /* The values of the PNG_FILLER_ defines should NOT be changed */
1433 # define PNG_FILLER_BEFORE 0
1434 # define PNG_FILLER_AFTER 1
1435 /* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
1436 PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
1437 png_uint_32 filler, int flags));
1438 #endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */
1440 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
1441 /* Swap bytes in 16-bit depth files. */
1442 PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
1445 #if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
1446 /* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
1447 PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
1450 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
1451 defined(PNG_WRITE_PACKSWAP_SUPPORTED)
1452 /* Swap packing order of pixels in bytes. */
1453 PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
1456 #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
1457 /* Converts files to legal bit depths. */
1458 PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
1462 #if defined(PNG_READ_INTERLACING_SUPPORTED) || \
1463 defined(PNG_WRITE_INTERLACING_SUPPORTED)
1464 /* Have the code handle the interlacing. Returns the number of passes.
1465 * MUST be called before png_read_update_info or png_start_read_image,
1466 * otherwise it will not have the desired effect. Note that it is still
1467 * necessary to call png_read_row or png_read_rows png_get_image_height
1468 * times for each pass.
1470 PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
1473 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
1474 /* Invert monochrome files */
1475 PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
1478 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1479 /* Handle alpha and tRNS by replacing with a background color. Prior to
1480 * libpng-1.5.4 this API must not be called before the PNG file header has been
1481 * read. Doing so will result in unexpected behavior and possible warnings or
1482 * errors if the PNG file contains a bKGD chunk.
1484 PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
1485 png_const_color_16p background_color, int background_gamma_code,
1486 int need_expand, double background_gamma))
1487 PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
1488 png_const_color_16p background_color, int background_gamma_code,
1489 int need_expand, png_fixed_point background_gamma))
1491 #ifdef PNG_READ_BACKGROUND_SUPPORTED
1492 # define PNG_BACKGROUND_GAMMA_UNKNOWN 0
1493 # define PNG_BACKGROUND_GAMMA_SCREEN 1
1494 # define PNG_BACKGROUND_GAMMA_FILE 2
1495 # define PNG_BACKGROUND_GAMMA_UNIQUE 3
1498 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1499 /* Scale a 16-bit depth file down to 8-bit, accurately. */
1500 PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
1503 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1504 #define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
1505 /* Strip the second byte of information from a 16-bit depth file. */
1506 PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
1509 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1510 /* Turn on quantizing, and reduce the palette to the number of colors
1513 PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
1514 png_colorp palette, int num_palette, int maximum_colors,
1515 png_const_uint_16p histogram, int full_quantize));
1518 #ifdef PNG_READ_GAMMA_SUPPORTED
1519 /* The threshold on gamma processing is configurable but hard-wired into the
1520 * library. The following is the floating point variant.
1522 #define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
1524 /* Handle gamma correction. Screen_gamma=(display_exponent).
1525 * NOTE: this API simply sets the screen and file gamma values. It will
1526 * therefore override the value for gamma in a PNG file if it is called after
1527 * the file header has been read - use with care - call before reading the PNG
1528 * file for best results!
1530 * These routines accept the same gamma values as png_set_alpha_mode (described
1531 * above). The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
1532 * API (floating point or fixed.) Notice, however, that the 'file_gamma' value
1533 * is the inverse of a 'screen gamma' value.
1535 PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
1536 double screen_gamma, double override_file_gamma))
1537 PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
1538 png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
1541 #ifdef PNG_WRITE_FLUSH_SUPPORTED
1542 /* Set how many lines between output flushes - 0 for no flushing */
1543 PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
1544 /* Flush the current PNG output buffer */
1545 PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
1548 /* Optional update palette with requested transformations */
1549 PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
1551 /* Optional call to update the users info structure */
1552 PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
1553 png_inforp info_ptr));
1555 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1556 /* Read one or more rows of image data. */
1557 PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
1558 png_bytepp display_row, png_uint_32 num_rows));
1561 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1562 /* Read a row of data. */
1563 PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
1564 png_bytep display_row));
1567 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1568 /* Read the whole image into memory at once. */
1569 PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
1572 /* Write a row of image data */
1573 PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
1574 png_const_bytep row));
1576 /* Write a few rows of image data: (*row) is not written; however, the type
1577 * is declared as writeable to maintain compatibility with previous versions
1578 * of libpng and to allow the 'display_row' array from read_rows to be passed
1579 * unchanged to write_rows.
1581 PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
1582 png_uint_32 num_rows));
1584 /* Write the image data */
1585 PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
1587 /* Write the end of the PNG file. */
1588 PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
1589 png_inforp info_ptr));
1591 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1592 /* Read the end of the PNG file. */
1593 PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
1596 /* Free any memory associated with the png_info_struct */
1597 PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
1598 png_infopp info_ptr_ptr));
1600 /* Free any memory associated with the png_struct and the png_info_structs */
1601 PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
1602 png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
1604 /* Free any memory associated with the png_struct and the png_info_structs */
1605 PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
1606 png_infopp info_ptr_ptr));
1608 /* Set the libpng method of handling chunk CRC errors */
1609 PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
1612 /* Values for png_set_crc_action() say how to handle CRC errors in
1613 * ancillary and critical chunks, and whether to use the data contained
1614 * therein. Note that it is impossible to "discard" data in a critical
1615 * chunk. For versions prior to 0.90, the action was always error/quit,
1616 * whereas in version 0.90 and later, the action for CRC errors in ancillary
1617 * chunks is warn/discard. These values should NOT be changed.
1619 * value action:critical action:ancillary
1621 #define PNG_CRC_DEFAULT 0 /* error/quit warn/discard data */
1622 #define PNG_CRC_ERROR_QUIT 1 /* error/quit error/quit */
1623 #define PNG_CRC_WARN_DISCARD 2 /* (INVALID) warn/discard data */
1624 #define PNG_CRC_WARN_USE 3 /* warn/use data warn/use data */
1625 #define PNG_CRC_QUIET_USE 4 /* quiet/use data quiet/use data */
1626 #define PNG_CRC_NO_CHANGE 5 /* use current value use current value */
1628 /* These functions give the user control over the scan-line filtering in
1629 * libpng and the compression methods used by zlib. These functions are
1630 * mainly useful for testing, as the defaults should work with most users.
1631 * Those users who are tight on memory or want faster performance at the
1632 * expense of compression can modify them. See the compression library
1633 * header file (zlib.h) for an explination of the compression functions.
1636 /* Set the filtering method(s) used by libpng. Currently, the only valid
1637 * value for "method" is 0.
1639 PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
1642 /* Flags for png_set_filter() to say which filters to use. The flags
1643 * are chosen so that they don't conflict with real filter types
1644 * below, in case they are supplied instead of the #defined constants.
1645 * These values should NOT be changed.
1647 #define PNG_NO_FILTERS 0x00
1648 #define PNG_FILTER_NONE 0x08
1649 #define PNG_FILTER_SUB 0x10
1650 #define PNG_FILTER_UP 0x20
1651 #define PNG_FILTER_AVG 0x40
1652 #define PNG_FILTER_PAETH 0x80
1653 #define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
1654 PNG_FILTER_AVG | PNG_FILTER_PAETH)
1656 /* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
1657 * These defines should NOT be changed.
1659 #define PNG_FILTER_VALUE_NONE 0
1660 #define PNG_FILTER_VALUE_SUB 1
1661 #define PNG_FILTER_VALUE_UP 2
1662 #define PNG_FILTER_VALUE_AVG 3
1663 #define PNG_FILTER_VALUE_PAETH 4
1664 #define PNG_FILTER_VALUE_LAST 5
1666 #ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
1667 /* The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
1668 * defines, either the default (minimum-sum-of-absolute-differences), or
1669 * the experimental method (weighted-minimum-sum-of-absolute-differences).
1671 * Weights are factors >= 1.0, indicating how important it is to keep the
1672 * filter type consistent between rows. Larger numbers mean the current
1673 * filter is that many times as likely to be the same as the "num_weights"
1674 * previous filters. This is cumulative for each previous row with a weight.
1675 * There needs to be "num_weights" values in "filter_weights", or it can be
1676 * NULL if the weights aren't being specified. Weights have no influence on
1677 * the selection of the first row filter. Well chosen weights can (in theory)
1678 * improve the compression for a given image.
1680 * Costs are factors >= 1.0 indicating the relative decoding costs of a
1681 * filter type. Higher costs indicate more decoding expense, and are
1682 * therefore less likely to be selected over a filter with lower computational
1683 * costs. There needs to be a value in "filter_costs" for each valid filter
1684 * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
1685 * setting the costs. Costs try to improve the speed of decompression without
1686 * unduly increasing the compressed image size.
1688 * A negative weight or cost indicates the default value is to be used, and
1689 * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
1690 * The default values for both weights and costs are currently 1.0, but may
1691 * change if good general weighting/cost heuristics can be found. If both
1692 * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
1693 * to the UNWEIGHTED method, but with added encoding time/computation.
1695 PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
1696 int heuristic_method, int num_weights, png_const_doublep filter_weights,
1697 png_const_doublep filter_costs))
1698 PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
1699 (png_structrp png_ptr, int heuristic_method, int num_weights,
1700 png_const_fixed_point_p filter_weights,
1701 png_const_fixed_point_p filter_costs))
1702 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
1704 /* Heuristic used for row filter selection. These defines should NOT be
1707 #define PNG_FILTER_HEURISTIC_DEFAULT 0 /* Currently "UNWEIGHTED" */
1708 #define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 /* Used by libpng < 0.95 */
1709 #define PNG_FILTER_HEURISTIC_WEIGHTED 2 /* Experimental feature */
1710 #define PNG_FILTER_HEURISTIC_LAST 3 /* Not a valid value */
1712 #ifdef PNG_WRITE_SUPPORTED
1713 /* Set the library compression level. Currently, valid values range from
1714 * 0 - 9, corresponding directly to the zlib compression levels 0 - 9
1715 * (0 - no compression, 9 - "maximal" compression). Note that tests have
1716 * shown that zlib compression levels 3-6 usually perform as well as level 9
1717 * for PNG images, and do considerably fewer caclulations. In the future,
1718 * these values may not correspond directly to the zlib compression levels.
1720 PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
1723 PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
1726 PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
1729 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1730 * smaller value of window_bits if it can do so safely.
1732 PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
1735 PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
1739 #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
1740 /* Also set zlib parameters for compressing non-IDAT chunks */
1741 PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
1744 PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
1747 PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
1750 /* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
1751 * smaller value of window_bits if it can do so safely.
1753 PNG_EXPORT(225, void, png_set_text_compression_window_bits,
1754 (png_structrp png_ptr, int window_bits));
1756 PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
1758 #endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
1760 /* These next functions are called for input/output, memory, and error
1761 * handling. They are in the file pngrio.c, pngwio.c, and pngerror.c,
1762 * and call standard C I/O routines such as fread(), fwrite(), and
1763 * fprintf(). These functions can be made to use other I/O routines
1764 * at run time for those applications that need to handle I/O in a
1765 * different manner by calling png_set_???_fn(). See libpng-manual.txt for
1769 #ifdef PNG_STDIO_SUPPORTED
1770 /* Initialize the input/output for the PNG file to the default functions. */
1771 PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
1774 /* Replace the (error and abort), and warning functions with user
1775 * supplied functions. If no messages are to be printed you must still
1776 * write and use replacement functions. The replacement error_fn should
1777 * still do a longjmp to the last setjmp location if you are using this
1778 * method of error handling. If error_fn or warning_fn is NULL, the
1779 * default function will be used.
1782 PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
1783 png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
1785 /* Return the user pointer associated with the error functions */
1786 PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
1788 /* Replace the default data output functions with a user supplied one(s).
1789 * If buffered output is not used, then output_flush_fn can be set to NULL.
1790 * If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
1791 * output_flush_fn will be ignored (and thus can be NULL).
1792 * It is probably a mistake to use NULL for output_flush_fn if
1793 * write_data_fn is not also NULL unless you have built libpng with
1794 * PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
1795 * default flush function, which uses the standard *FILE structure, will
1798 PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
1799 png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
1801 /* Replace the default data input function with a user supplied one. */
1802 PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
1803 png_rw_ptr read_data_fn));
1805 /* Return the user pointer associated with the I/O functions */
1806 PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
1808 PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
1809 png_read_status_ptr read_row_fn));
1811 PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
1812 png_write_status_ptr write_row_fn));
1814 #ifdef PNG_USER_MEM_SUPPORTED
1815 /* Replace the default memory allocation functions with user supplied one(s). */
1816 PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
1817 png_malloc_ptr malloc_fn, png_free_ptr free_fn));
1818 /* Return the user pointer associated with the memory functions */
1819 PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
1822 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
1823 PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
1824 png_user_transform_ptr read_user_transform_fn));
1827 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
1828 PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
1829 png_user_transform_ptr write_user_transform_fn));
1832 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
1833 PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
1834 png_voidp user_transform_ptr, int user_transform_depth,
1835 int user_transform_channels));
1836 /* Return the user pointer associated with the user transform functions */
1837 PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
1838 (png_const_structrp png_ptr));
1841 #ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
1842 /* Return information about the row currently being processed. Note that these
1843 * APIs do not fail but will return unexpected results if called outside a user
1844 * transform callback. Also note that when transforming an interlaced image the
1845 * row number is the row number within the sub-image of the interlace pass, so
1846 * the value will increase to the height of the sub-image (not the full image)
1847 * then reset to 0 for the next pass.
1849 * Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
1850 * find the output pixel (x,y) given an interlaced sub-image pixel
1851 * (row,col,pass). (See below for these macros.)
1853 PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
1854 PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
1857 #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
1858 /* This callback is called only for *unknown* chunks. If
1859 * PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
1860 * chunks to be treated as unknown, however in this case the callback must do
1861 * any processing required by the chunk (e.g. by calling the appropriate
1864 * There is no write support - on write, by default, all the chunks in the
1865 * 'unknown' list are written in the specified position.
1867 * The integer return from the callback function is interpreted thus:
1869 * negative: An error occured, png_chunk_error will be called.
1870 * zero: The chunk was not handled, the chunk will be saved. A critical
1871 * chunk will cause an error at this point unless it is to be saved.
1872 * positive: The chunk was handled, libpng will ignore/discard it.
1874 * See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
1875 * how this behavior will change in libpng 1.7
1877 PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
1878 png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
1881 #ifdef PNG_USER_CHUNKS_SUPPORTED
1882 PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
1885 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1886 /* Sets the function callbacks for the push reader, and a pointer to a
1887 * user-defined structure available to the callback functions.
1889 PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
1890 png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
1891 png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
1893 /* Returns the user pointer associated with the push read functions */
1894 PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
1895 (png_const_structrp png_ptr));
1897 /* Function to be called when data becomes available */
1898 PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
1899 png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
1901 /* A function which may be called *only* within png_process_data to stop the
1902 * processing of any more data. The function returns the number of bytes
1903 * remaining, excluding any that libpng has cached internally. A subsequent
1904 * call to png_process_data must supply these bytes again. If the argument
1905 * 'save' is set to true the routine will first save all the pending data and
1906 * will always return 0.
1908 PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
1910 /* A function which may be called *only* outside (after) a call to
1911 * png_process_data. It returns the number of bytes of data to skip in the
1912 * input. Normally it will return 0, but if it returns a non-zero value the
1913 * application must skip than number of bytes of input data and pass the
1914 * following data to the next call to png_process_data.
1916 PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
1918 #ifdef PNG_READ_INTERLACING_SUPPORTED
1919 /* Function that combines rows. 'new_row' is a flag that should come from
1920 * the callback and be non-NULL if anything needs to be done; the library
1921 * stores its own version of the new data internally and ignores the passed
1924 PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
1925 png_bytep old_row, png_const_bytep new_row));
1926 #endif /* PNG_READ_INTERLACING_SUPPORTED */
1927 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1929 PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
1930 png_alloc_size_t size), PNG_ALLOCATED);
1931 /* Added at libpng version 1.4.0 */
1932 PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
1933 png_alloc_size_t size), PNG_ALLOCATED);
1935 /* Added at libpng version 1.2.4 */
1936 PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
1937 png_alloc_size_t size), PNG_ALLOCATED);
1939 /* Frees a pointer allocated by png_malloc() */
1940 PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
1942 /* Free data that was allocated internally */
1943 PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
1944 png_inforp info_ptr, png_uint_32 free_me, int num));
1946 /* Reassign responsibility for freeing existing data, whether allocated
1947 * by libpng or by the application; this works on the png_info structure passed
1948 * in, it does not change the state for other png_info structures.
1950 * It is unlikely that this function works correctly as of 1.6.0 and using it
1951 * may result either in memory leaks or double free of allocated data.
1953 PNG_EXPORTA(99, void, png_data_freer, (png_const_structrp png_ptr,
1954 png_inforp info_ptr, int freer, png_uint_32 mask), PNG_DEPRECATED);
1956 /* Assignments for png_data_freer */
1957 #define PNG_DESTROY_WILL_FREE_DATA 1
1958 #define PNG_SET_WILL_FREE_DATA 1
1959 #define PNG_USER_WILL_FREE_DATA 2
1960 /* Flags for png_ptr->free_me and info_ptr->free_me */
1961 #define PNG_FREE_HIST 0x0008
1962 #define PNG_FREE_ICCP 0x0010
1963 #define PNG_FREE_SPLT 0x0020
1964 #define PNG_FREE_ROWS 0x0040
1965 #define PNG_FREE_PCAL 0x0080
1966 #define PNG_FREE_SCAL 0x0100
1967 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
1968 # define PNG_FREE_UNKN 0x0200
1970 /* PNG_FREE_LIST 0x0400 removed in 1.6.0 because it is ignored */
1971 #define PNG_FREE_PLTE 0x1000
1972 #define PNG_FREE_TRNS 0x2000
1973 #define PNG_FREE_TEXT 0x4000
1974 #define PNG_FREE_ALL 0x7fff
1975 #define PNG_FREE_MUL 0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
1977 #ifdef PNG_USER_MEM_SUPPORTED
1978 PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
1979 png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
1980 PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
1981 png_voidp ptr), PNG_DEPRECATED);
1984 #ifdef PNG_ERROR_TEXT_SUPPORTED
1985 /* Fatal error in PNG image of libpng - can't continue */
1986 PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
1987 png_const_charp error_message), PNG_NORETURN);
1989 /* The same, but the chunk name is prepended to the error string. */
1990 PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
1991 png_const_charp error_message), PNG_NORETURN);
1994 /* Fatal error in PNG image of libpng - can't continue */
1995 PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
1998 #ifdef PNG_WARNINGS_SUPPORTED
1999 /* Non-fatal error in libpng. Can continue, but may have a problem. */
2000 PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
2001 png_const_charp warning_message));
2003 /* Non-fatal error in libpng, chunk name is prepended to message. */
2004 PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
2005 png_const_charp warning_message));
2008 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
2009 /* Benign error in libpng. Can continue, but may have a problem.
2010 * User can choose whether to handle as a fatal error or as a warning. */
2011 PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
2012 png_const_charp warning_message));
2014 #ifdef PNG_READ_SUPPORTED
2015 /* Same, chunk name is prepended to message (only during read) */
2016 PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
2017 png_const_charp warning_message));
2020 PNG_EXPORT(109, void, png_set_benign_errors,
2021 (png_structrp png_ptr, int allowed));
2023 # ifdef PNG_ALLOW_BENIGN_ERRORS
2024 # define png_benign_error png_warning
2025 # define png_chunk_benign_error png_chunk_warning
2027 # define png_benign_error png_error
2028 # define png_chunk_benign_error png_chunk_error
2032 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
2033 * Similarly, the png_get_<chunk> calls are used to read values from the
2034 * png_info_struct, either storing the parameters in the passed variables, or
2035 * setting pointers into the png_info_struct where the data is stored. The
2036 * png_get_<chunk> functions return a non-zero value if the data was available
2037 * in info_ptr, or return zero and do not change any of the parameters if the
2038 * data was not available.
2040 * These functions should be used instead of directly accessing png_info
2041 * to avoid problems with future changes in the size and internal layout of
2044 /* Returns "flag" if chunk data is valid in info_ptr. */
2045 PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
2046 png_const_inforp info_ptr, png_uint_32 flag));
2048 /* Returns number of bytes needed to hold a transformed row. */
2049 PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
2050 png_const_inforp info_ptr));
2052 #ifdef PNG_INFO_IMAGE_SUPPORTED
2053 /* Returns row_pointers, which is an array of pointers to scanlines that was
2054 * returned from png_read_png().
2056 PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
2057 png_const_inforp info_ptr));
2059 /* Set row_pointers, which is an array of pointers to scanlines for use
2060 * by png_write_png().
2062 PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
2063 png_inforp info_ptr, png_bytepp row_pointers));
2066 /* Returns number of color channels in image. */
2067 PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
2068 png_const_inforp info_ptr));
2070 #ifdef PNG_EASY_ACCESS_SUPPORTED
2071 /* Returns image width in pixels. */
2072 PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
2073 png_const_inforp info_ptr));
2075 /* Returns image height in pixels. */
2076 PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
2077 png_const_inforp info_ptr));
2079 /* Returns image bit_depth. */
2080 PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
2081 png_const_inforp info_ptr));
2083 /* Returns image color_type. */
2084 PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
2085 png_const_inforp info_ptr));
2087 /* Returns image filter_type. */
2088 PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
2089 png_const_inforp info_ptr));
2091 /* Returns image interlace_type. */
2092 PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
2093 png_const_inforp info_ptr));
2095 /* Returns image compression_type. */
2096 PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
2097 png_const_inforp info_ptr));
2099 /* Returns image resolution in pixels per meter, from pHYs chunk data. */
2100 PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
2101 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2102 PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
2103 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2104 PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
2105 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2107 /* Returns pixel aspect ratio, computed from pHYs chunk data. */
2108 PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
2109 (png_const_structrp png_ptr, png_const_inforp info_ptr))
2110 PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
2111 (png_const_structrp png_ptr, png_const_inforp info_ptr))
2113 /* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
2114 PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
2115 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2116 PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
2117 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2118 PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
2119 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2120 PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
2121 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2123 #endif /* PNG_EASY_ACCESS_SUPPORTED */
2125 #ifdef PNG_READ_SUPPORTED
2126 /* Returns pointer to signature string read from PNG header */
2127 PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
2128 png_const_inforp info_ptr));
2131 #ifdef PNG_bKGD_SUPPORTED
2132 PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
2133 png_inforp info_ptr, png_color_16p *background));
2136 #ifdef PNG_bKGD_SUPPORTED
2137 PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
2138 png_inforp info_ptr, png_const_color_16p background));
2141 #ifdef PNG_cHRM_SUPPORTED
2142 PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
2143 png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
2144 double *red_y, double *green_x, double *green_y, double *blue_x,
2146 PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
2147 png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
2148 double *green_X, double *green_Y, double *green_Z, double *blue_X,
2149 double *blue_Y, double *blue_Z))
2150 PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
2151 (png_const_structrp png_ptr, png_const_inforp info_ptr,
2152 png_fixed_point *int_white_x, png_fixed_point *int_white_y,
2153 png_fixed_point *int_red_x, png_fixed_point *int_red_y,
2154 png_fixed_point *int_green_x, png_fixed_point *int_green_y,
2155 png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
2156 PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
2157 (png_const_structrp png_ptr, png_const_inforp info_ptr,
2158 png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
2159 png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
2160 png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
2161 png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
2162 png_fixed_point *int_blue_Z))
2165 #ifdef PNG_cHRM_SUPPORTED
2166 PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
2167 png_inforp info_ptr,
2168 double white_x, double white_y, double red_x, double red_y, double green_x,
2169 double green_y, double blue_x, double blue_y))
2170 PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
2171 png_inforp info_ptr, double red_X, double red_Y, double red_Z,
2172 double green_X, double green_Y, double green_Z, double blue_X,
2173 double blue_Y, double blue_Z))
2174 PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
2175 png_inforp info_ptr, png_fixed_point int_white_x,
2176 png_fixed_point int_white_y, png_fixed_point int_red_x,
2177 png_fixed_point int_red_y, png_fixed_point int_green_x,
2178 png_fixed_point int_green_y, png_fixed_point int_blue_x,
2179 png_fixed_point int_blue_y))
2180 PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
2181 png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
2182 png_fixed_point int_red_Z, png_fixed_point int_green_X,
2183 png_fixed_point int_green_Y, png_fixed_point int_green_Z,
2184 png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
2185 png_fixed_point int_blue_Z))
2188 #ifdef PNG_gAMA_SUPPORTED
2189 PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
2190 png_const_inforp info_ptr, double *file_gamma))
2191 PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
2192 (png_const_structrp png_ptr, png_const_inforp info_ptr,
2193 png_fixed_point *int_file_gamma))
2196 #ifdef PNG_gAMA_SUPPORTED
2197 PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
2198 png_inforp info_ptr, double file_gamma))
2199 PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
2200 png_inforp info_ptr, png_fixed_point int_file_gamma))
2203 #ifdef PNG_hIST_SUPPORTED
2204 PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
2205 png_inforp info_ptr, png_uint_16p *hist));
2208 #ifdef PNG_hIST_SUPPORTED
2209 PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
2210 png_inforp info_ptr, png_const_uint_16p hist));
2213 PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
2214 png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
2215 int *bit_depth, int *color_type, int *interlace_method,
2216 int *compression_method, int *filter_method));
2218 PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
2219 png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
2220 int color_type, int interlace_method, int compression_method,
2221 int filter_method));
2223 #ifdef PNG_oFFs_SUPPORTED
2224 PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
2225 png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
2229 #ifdef PNG_oFFs_SUPPORTED
2230 PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
2231 png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
2235 #ifdef PNG_pCAL_SUPPORTED
2236 PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
2237 png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
2238 png_int_32 *X1, int *type, int *nparams, png_charp *units,
2239 png_charpp *params));
2242 #ifdef PNG_pCAL_SUPPORTED
2243 PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
2244 png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
2245 int type, int nparams, png_const_charp units, png_charpp params));
2248 #ifdef PNG_pHYs_SUPPORTED
2249 PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
2250 png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2254 #ifdef PNG_pHYs_SUPPORTED
2255 PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
2256 png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
2259 PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
2260 png_inforp info_ptr, png_colorp *palette, int *num_palette));
2262 PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
2263 png_inforp info_ptr, png_const_colorp palette, int num_palette));
2265 #ifdef PNG_sBIT_SUPPORTED
2266 PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
2267 png_inforp info_ptr, png_color_8p *sig_bit));
2270 #ifdef PNG_sBIT_SUPPORTED
2271 PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
2272 png_inforp info_ptr, png_const_color_8p sig_bit));
2275 #ifdef PNG_sRGB_SUPPORTED
2276 PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
2277 png_const_inforp info_ptr, int *file_srgb_intent));
2280 #ifdef PNG_sRGB_SUPPORTED
2281 PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
2282 png_inforp info_ptr, int srgb_intent));
2283 PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
2284 png_inforp info_ptr, int srgb_intent));
2287 #ifdef PNG_iCCP_SUPPORTED
2288 PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
2289 png_inforp info_ptr, png_charpp name, int *compression_type,
2290 png_bytepp profile, png_uint_32 *proflen));
2293 #ifdef PNG_iCCP_SUPPORTED
2294 PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
2295 png_inforp info_ptr, png_const_charp name, int compression_type,
2296 png_const_bytep profile, png_uint_32 proflen));
2299 #ifdef PNG_sPLT_SUPPORTED
2300 PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
2301 png_inforp info_ptr, png_sPLT_tpp entries));
2304 #ifdef PNG_sPLT_SUPPORTED
2305 PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
2306 png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
2309 #ifdef PNG_TEXT_SUPPORTED
2310 /* png_get_text also returns the number of text chunks in *num_text */
2311 PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
2312 png_inforp info_ptr, png_textp *text_ptr, int *num_text));
2315 /* Note while png_set_text() will accept a structure whose text,
2316 * language, and translated keywords are NULL pointers, the structure
2317 * returned by png_get_text will always contain regular
2318 * zero-terminated C strings. They might be empty strings but
2319 * they will never be NULL pointers.
2322 #ifdef PNG_TEXT_SUPPORTED
2323 PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
2324 png_inforp info_ptr, png_const_textp text_ptr, int num_text));
2327 #ifdef PNG_tIME_SUPPORTED
2328 PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
2329 png_inforp info_ptr, png_timep *mod_time));
2332 #ifdef PNG_tIME_SUPPORTED
2333 PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
2334 png_inforp info_ptr, png_const_timep mod_time));
2337 #ifdef PNG_tRNS_SUPPORTED
2338 PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
2339 png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
2340 png_color_16p *trans_color));
2343 #ifdef PNG_tRNS_SUPPORTED
2344 PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
2345 png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
2346 png_const_color_16p trans_color));
2349 #ifdef PNG_sCAL_SUPPORTED
2350 PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
2351 png_const_inforp info_ptr, int *unit, double *width, double *height))
2352 #if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
2353 defined(PNG_FLOATING_POINT_SUPPORTED)
2354 /* NOTE: this API is currently implemented using floating point arithmetic,
2355 * consequently it can only be used on systems with floating point support.
2356 * In any case the range of values supported by png_fixed_point is small and it
2357 * is highly recommended that png_get_sCAL_s be used instead.
2359 PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
2360 (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2361 png_fixed_point *width, png_fixed_point *height))
2363 PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
2364 (png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
2365 png_charpp swidth, png_charpp sheight));
2367 PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
2368 png_inforp info_ptr, int unit, double width, double height))
2369 PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
2370 png_inforp info_ptr, int unit, png_fixed_point width,
2371 png_fixed_point height))
2372 PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
2373 png_inforp info_ptr, int unit,
2374 png_const_charp swidth, png_const_charp sheight));
2375 #endif /* PNG_sCAL_SUPPORTED */
2377 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
2378 /* Provide the default handling for all unknown chunks or, optionally, for
2379 * specific unknown chunks.
2381 * NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
2382 * ignored and the default was used, the per-chunk setting only had an effect on
2383 * write. If you wish to have chunk-specific handling on read in code that must
2384 * work on earlier versions you must use a user chunk callback to specify the
2385 * desired handling (keep or discard.)
2387 * The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below. The
2388 * parameter is interpreted as follows:
2391 * PNG_HANDLE_CHUNK_AS_DEFAULT:
2392 * Known chunks: do normal libpng processing, do not keep the chunk (but
2393 * see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
2394 * Unknown chunks: for a specific chunk use the global default, when used
2395 * as the default discard the chunk data.
2396 * PNG_HANDLE_CHUNK_NEVER:
2397 * Discard the chunk data.
2398 * PNG_HANDLE_CHUNK_IF_SAFE:
2399 * Keep the chunk data if the chunk is not critical else raise a chunk
2401 * PNG_HANDLE_CHUNK_ALWAYS:
2402 * Keep the chunk data.
2404 * If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
2405 * below. Notice that specifying "AS_DEFAULT" as a global default is equivalent
2406 * to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
2407 * it simply resets the behavior to the libpng default.
2409 * INTERACTION WTIH USER CHUNK CALLBACKS:
2410 * The per-chunk handling is always used when there is a png_user_chunk_ptr
2411 * callback and the callback returns 0; the chunk is then always stored *unless*
2412 * it is critical and the per-chunk setting is other than ALWAYS. Notice that
2413 * the global default is *not* used in this case. (In effect the per-chunk
2414 * value is incremented to at least IF_SAFE.)
2416 * IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
2417 * per-chunk defaults will be honored. If you want to preserve the current
2418 * behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
2419 * as the default - if you don't do this libpng 1.6 will issue a warning.
2421 * If you want unhandled unknown chunks to be discarded in libpng 1.6 and
2422 * earlier simply return '1' (handled).
2424 * PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
2425 * If this is *not* set known chunks will always be handled by libpng and
2426 * will never be stored in the unknown chunk list. Known chunks listed to
2427 * png_set_keep_unknown_chunks will have no effect. If it is set then known
2428 * chunks listed with a keep other than AS_DEFAULT will *never* be processed
2429 * by libpng, in addition critical chunks must either be processed by the
2430 * callback or saved.
2432 * The IHDR and IEND chunks must not be listed. Because this turns off the
2433 * default handling for chunks that would otherwise be recognized the
2434 * behavior of libpng transformations may well become incorrect!
2437 * When writing chunks the options only apply to the chunks specified by
2438 * png_set_unknown_chunks (below), libpng will *always* write known chunks
2439 * required by png_set_ calls and will always write the core critical chunks
2440 * (as required for PLTE).
2442 * Each chunk in the png_set_unknown_chunks list is looked up in the
2443 * png_set_keep_unknown_chunks list to find the keep setting, this is then
2444 * interpreted as follows:
2446 * PNG_HANDLE_CHUNK_AS_DEFAULT:
2447 * Write safe-to-copy chunks and write other chunks if the global
2448 * default is set to _ALWAYS, otherwise don't write this chunk.
2449 * PNG_HANDLE_CHUNK_NEVER:
2450 * Do not write the chunk.
2451 * PNG_HANDLE_CHUNK_IF_SAFE:
2452 * Write the chunk if it is safe-to-copy, otherwise do not write it.
2453 * PNG_HANDLE_CHUNK_ALWAYS:
2456 * Note that the default behavior is effectively the opposite of the read case -
2457 * in read unknown chunks are not stored by default, in write they are written
2458 * by default. Also the behavior of PNG_HANDLE_CHUNK_IF_SAFE is very different
2459 * - on write the safe-to-copy bit is checked, on read the critical bit is
2460 * checked and on read if the chunk is critical an error will be raised.
2464 * If num_chunks is positive, then the "keep" parameter specifies the manner
2465 * for handling only those chunks appearing in the chunk_list array,
2466 * otherwise the chunk list array is ignored.
2468 * If num_chunks is 0 the "keep" parameter specifies the default behavior for
2469 * unknown chunks, as described above.
2471 * If num_chunks is negative, then the "keep" parameter specifies the manner
2472 * for handling all unknown chunks plus all chunks recognized by libpng
2473 * except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
2474 * be processed by libpng.
2476 PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
2477 int keep, png_const_bytep chunk_list, int num_chunks));
2479 /* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
2480 * the result is therefore true (non-zero) if special handling is required,
2481 * false for the default handling.
2483 PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
2484 png_const_bytep chunk_name));
2487 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
2488 PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
2489 png_inforp info_ptr, png_const_unknown_chunkp unknowns,
2491 /* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
2492 * unknowns to the location currently stored in the png_struct. This is
2493 * invariably the wrong value on write. To fix this call the following API
2494 * for each chunk in the list with the correct location. If you know your
2495 * code won't be compiled on earlier versions you can rely on
2496 * png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
2497 * the correct thing.
2500 PNG_EXPORT(175, void, png_set_unknown_chunk_location,
2501 (png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
2503 PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
2504 png_inforp info_ptr, png_unknown_chunkpp entries));
2507 /* Png_free_data() will turn off the "valid" flag for anything it frees.
2508 * If you need to turn it off for a chunk that your application has freed,
2509 * you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
2511 PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
2512 png_inforp info_ptr, int mask));
2514 #ifdef PNG_INFO_IMAGE_SUPPORTED
2515 /* The "params" pointer is currently not used and is for future expansion. */
2516 PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
2517 int transforms, png_voidp params));
2518 PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
2519 int transforms, png_voidp params));
2522 PNG_EXPORT(180, png_const_charp, png_get_copyright,
2523 (png_const_structrp png_ptr));
2524 PNG_EXPORT(181, png_const_charp, png_get_header_ver,
2525 (png_const_structrp png_ptr));
2526 PNG_EXPORT(182, png_const_charp, png_get_header_version,
2527 (png_const_structrp png_ptr));
2528 PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
2529 (png_const_structrp png_ptr));
2531 #ifdef PNG_MNG_FEATURES_SUPPORTED
2532 PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
2533 png_uint_32 mng_features_permitted));
2536 /* For use in png_set_keep_unknown, added to version 1.2.6 */
2537 #define PNG_HANDLE_CHUNK_AS_DEFAULT 0
2538 #define PNG_HANDLE_CHUNK_NEVER 1
2539 #define PNG_HANDLE_CHUNK_IF_SAFE 2
2540 #define PNG_HANDLE_CHUNK_ALWAYS 3
2541 #define PNG_HANDLE_CHUNK_LAST 4
2543 /* Strip the prepended error numbers ("#nnn ") from error and warning
2544 * messages before passing them to the error or warning handler.
2546 #ifdef PNG_ERROR_NUMBERS_SUPPORTED
2547 PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
2548 png_uint_32 strip_mode));
2551 /* Added in libpng-1.2.6 */
2552 #ifdef PNG_SET_USER_LIMITS_SUPPORTED
2553 PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
2554 png_uint_32 user_width_max, png_uint_32 user_height_max));
2555 PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
2556 (png_const_structrp png_ptr));
2557 PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
2558 (png_const_structrp png_ptr));
2559 /* Added in libpng-1.4.0 */
2560 PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
2561 png_uint_32 user_chunk_cache_max));
2562 PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
2563 (png_const_structrp png_ptr));
2564 /* Added in libpng-1.4.1 */
2565 PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
2566 png_alloc_size_t user_chunk_cache_max));
2567 PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
2568 (png_const_structrp png_ptr));
2571 #if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
2572 PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
2573 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2575 PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
2576 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2578 PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
2579 (png_const_structrp png_ptr, png_const_inforp info_ptr));
2581 PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
2582 (png_const_structrp png_ptr, png_const_inforp info_ptr))
2583 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2584 PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
2585 (png_const_structrp png_ptr, png_const_inforp info_ptr))
2588 PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
2589 png_const_inforp info_ptr))
2590 #ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
2591 PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
2592 (png_const_structrp png_ptr, png_const_inforp info_ptr))
2595 # ifdef PNG_pHYs_SUPPORTED
2596 PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
2597 png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
2599 # endif /* PNG_pHYs_SUPPORTED */
2600 #endif /* PNG_INCH_CONVERSIONS_SUPPORTED */
2602 /* Added in libpng-1.4.0 */
2603 #ifdef PNG_IO_STATE_SUPPORTED
2604 PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
2606 /* Removed from libpng 1.6; use png_get_io_chunk_type. */
2607 PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
2610 PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
2611 (png_const_structrp png_ptr));
2613 /* The flags returned by png_get_io_state() are the following: */
2614 # define PNG_IO_NONE 0x0000 /* no I/O at this moment */
2615 # define PNG_IO_READING 0x0001 /* currently reading */
2616 # define PNG_IO_WRITING 0x0002 /* currently writing */
2617 # define PNG_IO_SIGNATURE 0x0010 /* currently at the file signature */
2618 # define PNG_IO_CHUNK_HDR 0x0020 /* currently at the chunk header */
2619 # define PNG_IO_CHUNK_DATA 0x0040 /* currently at the chunk data */
2620 # define PNG_IO_CHUNK_CRC 0x0080 /* currently at the chunk crc */
2621 # define PNG_IO_MASK_OP 0x000f /* current operation: reading/writing */
2622 # define PNG_IO_MASK_LOC 0x00f0 /* current location: sig/hdr/data/crc */
2623 #endif /* ?PNG_IO_STATE_SUPPORTED */
2625 /* Interlace support. The following macros are always defined so that if
2626 * libpng interlace handling is turned off the macros may be used to handle
2627 * interlaced images within the application.
2629 #define PNG_INTERLACE_ADAM7_PASSES 7
2631 /* Two macros to return the first row and first column of the original,
2632 * full, image which appears in a given pass. 'pass' is in the range 0
2633 * to 6 and the result is in the range 0 to 7.
2635 #define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
2636 #define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
2638 /* A macro to return the offset between pixels in the output row for a pair of
2639 * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
2640 * follows. Note that ROW_OFFSET is the offset from one row to the next whereas
2641 * COL_OFFSET is from one column to the next, within a row.
2643 #define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
2644 #define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))
2646 /* Two macros to help evaluate the number of rows or columns in each
2647 * pass. This is expressed as a shift - effectively log2 of the number or
2648 * rows or columns in each 8x8 tile of the original image.
2650 #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
2651 #define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)
2653 /* Hence two macros to determine the number of rows or columns in a given
2654 * pass of an image given its height or width. In fact these macros may
2655 * return non-zero even though the sub-image is empty, because the other
2656 * dimension may be empty for a small image.
2658 #define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
2659 -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
2660 #define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
2661 -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))
2663 /* For the reader row callbacks (both progressive and sequential) it is
2664 * necessary to find the row in the output image given a row in an interlaced
2665 * image, so two more macros:
2667 #define PNG_ROW_FROM_PASS_ROW(y_in, pass) \
2668 (((y_in)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
2669 #define PNG_COL_FROM_PASS_COL(x_in, pass) \
2670 (((x_in)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))
2672 /* Two macros which return a boolean (0 or 1) saying whether the given row
2673 * or column is in a particular pass. These use a common utility macro that
2674 * returns a mask for a given pass - the offset 'off' selects the row or
2675 * column version. The mask has the appropriate bit set for each column in
2678 #define PNG_PASS_MASK(pass,off) ( \
2679 ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
2680 ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))
2682 #define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
2683 ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
2684 #define PNG_COL_IN_INTERLACE_PASS(x, pass) \
2685 ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)
2687 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
2688 /* With these routines we avoid an integer divide, which will be slower on
2689 * most machines. However, it does take more operations than the corresponding
2690 * divide method, so it may be slower on a few RISC systems. There are two
2691 * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
2693 * Note that the rounding factors are NOT supposed to be the same! 128 and
2694 * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
2697 * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
2700 /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
2702 # define png_composite(composite, fg, alpha, bg) \
2703 { png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
2704 * (png_uint_16)(alpha) \
2705 + (png_uint_16)(bg)*(png_uint_16)(255 \
2706 - (png_uint_16)(alpha)) + 128); \
2707 (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
2709 # define png_composite_16(composite, fg, alpha, bg) \
2710 { png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
2711 * (png_uint_32)(alpha) \
2712 + (png_uint_32)(bg)*(65535 \
2713 - (png_uint_32)(alpha)) + 32768); \
2714 (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
2716 #else /* Standard method using integer division */
2718 # define png_composite(composite, fg, alpha, bg) \
2719 (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) + \
2720 (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
2723 # define png_composite_16(composite, fg, alpha, bg) \
2724 (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
2725 (png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) + \
2727 #endif /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */
2729 #ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
2730 PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
2731 PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
2732 PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
2735 PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
2736 png_const_bytep buf));
2737 /* No png_get_int_16 -- may be added if there's a real need for it. */
2739 /* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
2740 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2741 PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
2743 #ifdef PNG_SAVE_INT_32_SUPPORTED
2744 PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
2747 /* Place a 16-bit number into a buffer in PNG byte order.
2748 * The parameter is declared unsigned int, not png_uint_16,
2749 * just to avoid potential problems on pre-ANSI C compilers.
2751 #ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
2752 PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
2753 /* No png_save_int_16 -- may be added if there's a real need for it. */
2756 #ifdef PNG_USE_READ_MACROS
2757 /* Inline macros to do direct reads of bytes from the input buffer.
2758 * The png_get_int_32() routine assumes we are using two's complement
2759 * format for negative values, which is almost certainly true.
2761 # define PNG_get_uint_32(buf) \
2762 (((png_uint_32)(*(buf)) << 24) + \
2763 ((png_uint_32)(*((buf) + 1)) << 16) + \
2764 ((png_uint_32)(*((buf) + 2)) << 8) + \
2765 ((png_uint_32)(*((buf) + 3))))
2767 /* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
2768 * function) incorrectly returned a value of type png_uint_32.
2770 # define PNG_get_uint_16(buf) \
2772 (((unsigned int)(*(buf)) << 8) + \
2773 ((unsigned int)(*((buf) + 1)))))
2775 # define PNG_get_int_32(buf) \
2776 ((png_int_32)((*(buf) & 0x80) \
2777 ? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
2778 : (png_int_32)png_get_uint_32(buf)))
2780 /* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
2781 * but defining a macro name prefixed with PNG_PREFIX.
2784 # define png_get_uint_32(buf) PNG_get_uint_32(buf)
2785 # define png_get_uint_16(buf) PNG_get_uint_16(buf)
2786 # define png_get_int_32(buf) PNG_get_int_32(buf)
2790 /* No macros; revert to the (redefined) function */
2791 # define PNG_get_uint_32 (png_get_uint_32)
2792 # define PNG_get_uint_16 (png_get_uint_16)
2793 # define PNG_get_int_32 (png_get_int_32)
2797 /*******************************************************************************
2799 *******************************************************************************
2801 * Please read the documentation in libpng-manual.txt (TODO: write said
2802 * documentation) if you don't understand what follows.
2804 * The simplified API hides the details of both libpng and the PNG file format
2805 * itself. It allows PNG files to be read into a very limited number of
2806 * in-memory bitmap formats or to be written from the same formats. If these
2807 * formats do not accomodate your needs then you can, and should, use the more
2808 * sophisticated APIs above - these support a wide variety of in-memory formats
2809 * and a wide variety of sophisticated transformations to those formats as well
2810 * as a wide variety of APIs to manipulate ancillary information.
2812 * To read a PNG file using the simplified API:
2814 * 1) Declare a 'png_image' structure (see below) on the stack and set the
2815 * version field to PNG_IMAGE_VERSION.
2816 * 2) Call the appropriate png_image_begin_read... function.
2817 * 3) Set the png_image 'format' member to the required sample format.
2818 * 4) Allocate a buffer for the image and, if required, the color-map.
2819 * 5) Call png_image_finish_read to read the image and, if required, the
2820 * color-map into your buffers.
2822 * There are no restrictions on the format of the PNG input itself; all valid
2823 * color types, bit depths, and interlace methods are acceptable, and the
2824 * input image is transformed as necessary to the requested in-memory format
2825 * during the png_image_finish_read() step. The only caveat is that if you
2826 * request a color-mapped image from a PNG that is full-color or makes
2827 * complex use of an alpha channel the transformation is extremely lossy and the
2828 * result may look terrible.
2830 * To write a PNG file using the simplified API:
2832 * 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
2833 * 2) Initialize the members of the structure that describe the image, setting
2834 * the 'format' member to the format of the image samples.
2835 * 3) Call the appropriate png_image_write... function with a pointer to the
2836 * image and, if necessary, the color-map to write the PNG data.
2838 * png_image is a structure that describes the in-memory format of an image
2839 * when it is being read or defines the in-memory format of an image that you
2842 #define PNG_IMAGE_VERSION 1
2844 typedef struct png_control *png_controlp;
2847 png_controlp opaque; /* Initialize to NULL, free with png_image_free */
2848 png_uint_32 version; /* Set to PNG_IMAGE_VERSION */
2849 png_uint_32 width; /* Image width in pixels (columns) */
2850 png_uint_32 height; /* Image height in pixels (rows) */
2851 png_uint_32 format; /* Image format as defined below */
2852 png_uint_32 flags; /* A bit mask containing informational flags */
2853 png_uint_32 colormap_entries;
2854 /* Number of entries in the color-map */
2856 /* In the event of an error or warning the following field will be set to a
2857 * non-zero value and the 'message' field will contain a '\0' terminated
2858 * string with the libpng error or warning message. If both warnings and
2859 * an error were encountered, only the error is recorded. If there
2860 * are multiple warnings, only the first one is recorded.
2862 * The upper 30 bits of this value are reserved, the low two bits contain
2863 * a value as follows:
2865 # define PNG_IMAGE_WARNING 1
2866 # define PNG_IMAGE_ERROR 2
2868 * The result is a two bit code such that a value more than 1 indicates
2869 * a failure in the API just called:
2871 * 0 - no warning or error
2874 * 3 - error preceded by warning
2876 # define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
2878 png_uint_32 warning_or_error;
2881 } png_image, *png_imagep;
2883 /* The samples of the image have one to four channels whose components have
2884 * original values in the range 0 to 1.0:
2886 * 1: A single gray or luminance channel (G).
2887 * 2: A gray/luminance channel and an alpha channel (GA).
2888 * 3: Three red, green, blue color channels (RGB).
2889 * 4: Three color channels and an alpha channel (RGBA).
2891 * The components are encoded in one of two ways:
2893 * a) As a small integer, value 0..255, contained in a single byte. For the
2894 * alpha channel the original value is simply value/255. For the color or
2895 * luminance channels the value is encoded according to the sRGB specification
2896 * and matches the 8-bit format expected by typical display devices.
2898 * The color/gray channels are not scaled (pre-multiplied) by the alpha
2899 * channel and are suitable for passing to color management software.
2901 * b) As a value in the range 0..65535, contained in a 2-byte integer. All
2902 * channels can be converted to the original value by dividing by 65535; all
2903 * channels are linear. Color channels use the RGB encoding (RGB end-points) of
2904 * the sRGB specification. This encoding is identified by the
2905 * PNG_FORMAT_FLAG_LINEAR flag below.
2907 * When the simplified API needs to convert between sRGB and linear colorspaces,
2908 * the actual sRGB transfer curve defined in the sRGB specification (see the
2909 * article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
2910 * approximation used elsewhere in libpng.
2912 * When an alpha channel is present it is expected to denote pixel coverage
2913 * of the color or luminance channels and is returned as an associated alpha
2914 * channel: the color/gray channels are scaled (pre-multiplied) by the alpha
2917 * The samples are either contained directly in the image data, between 1 and 8
2918 * bytes per pixel according to the encoding, or are held in a color-map indexed
2919 * by bytes in the image data. In the case of a color-map the color-map entries
2920 * are individual samples, encoded as above, and the image data has one byte per
2921 * pixel to select the relevant sample from the color-map.
2926 * #defines to be used in png_image::format. Each #define identifies a
2927 * particular layout of sample data and, if present, alpha values. There are
2928 * separate defines for each of the two component encodings.
2930 * A format is built up using single bit flag values. All combinations are
2931 * valid. Formats can be built up from the flag values or you can use one of
2932 * the predefined values below. When testing formats always use the FORMAT_FLAG
2933 * macros to test for individual features - future versions of the library may
2936 * When reading or writing color-mapped images the format should be set to the
2937 * format of the entries in the color-map then png_image_{read,write}_colormap
2938 * called to read or write the color-map and set the format correctly for the
2939 * image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
2941 * NOTE: libpng can be built with particular features disabled, if you see
2942 * compiler errors because the definition of one of the following flags has been
2943 * compiled out it is because libpng does not have the required support. It is
2944 * possible, however, for the libpng configuration to enable the format on just
2945 * read or just write; in that case you may see an error at run time. You can
2946 * guard against this by checking for the definition of the appropriate
2947 * "_SUPPORTED" macro, one of:
2949 * PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
2951 #define PNG_FORMAT_FLAG_ALPHA 0x01U /* format with an alpha channel */
2952 #define PNG_FORMAT_FLAG_COLOR 0x02U /* color format: otherwise grayscale */
2953 #define PNG_FORMAT_FLAG_LINEAR 0x04U /* 2 byte channels else 1 byte */
2954 #define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
2956 #ifdef PNG_FORMAT_BGR_SUPPORTED
2957 # define PNG_FORMAT_FLAG_BGR 0x10U /* BGR colors, else order is RGB */
2960 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
2961 # define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
2964 /* Commonly used formats have predefined macros.
2966 * First the single byte (sRGB) formats:
2968 #define PNG_FORMAT_GRAY 0
2969 #define PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA
2970 #define PNG_FORMAT_AG (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
2971 #define PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR
2972 #define PNG_FORMAT_BGR (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
2973 #define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
2974 #define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
2975 #define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
2976 #define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
2978 /* Then the linear 2-byte formats. When naming these "Y" is used to
2979 * indicate a luminance (gray) channel.
2981 #define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
2982 #define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
2983 #define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
2984 #define PNG_FORMAT_LINEAR_RGB_ALPHA \
2985 (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
2987 /* With color-mapped formats the image data is one byte for each pixel, the byte
2988 * is an index into the color-map which is formatted as above. To obtain a
2989 * color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
2990 * to one of the above definitions, or you can use one of the definitions below.
2992 #define PNG_FORMAT_RGB_COLORMAP (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
2993 #define PNG_FORMAT_BGR_COLORMAP (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
2994 #define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
2995 #define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
2996 #define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
2997 #define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
3001 * These are convenience macros to derive information from a png_image
3002 * structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
3003 * actual image sample values - either the entries in the color-map or the
3004 * pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
3005 * for the pixels and will always return 1 for color-mapped formats. The
3006 * remaining macros return information about the rows in the image and the
3009 * NOTE: All the macros that take a png_image::format parameter are compile time
3010 * constants if the format parameter is, itself, a constant. Therefore these
3011 * macros can be used in array declarations and case labels where required.
3012 * Similarly the macros are also pre-processor constants (sizeof is not used) so
3013 * they can be used in #if tests.
3015 * First the information about the samples.
3017 #define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
3018 (((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
3019 /* Return the total number of channels in a given format: 1..4 */
3021 #define PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt)\
3022 ((((fmt) & PNG_FORMAT_FLAG_LINEAR) >> 2)+1)
3023 /* Return the size in bytes of a single component of a pixel or color-map
3024 * entry (as appropriate) in the image: 1 or 2.
3027 #define PNG_IMAGE_SAMPLE_SIZE(fmt)\
3028 (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * PNG_IMAGE_SAMPLE_COMPONENT_SIZE(fmt))
3029 /* This is the size of the sample data for one sample. If the image is
3030 * color-mapped it is the size of one color-map entry (and image pixels are
3031 * one byte in size), otherwise it is the size of one image pixel.
3034 #define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
3035 (PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
3036 /* The maximum size of the color-map required by the format expressed in a
3037 * count of components. This can be used to compile-time allocate a
3040 * png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
3042 * png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
3044 * Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
3045 * information from one of the png_image_begin_read_ APIs and dynamically
3046 * allocate the required memory.
3049 /* Corresponding information about the pixels */
3050 #define PNG_IMAGE_PIXEL_(test,fmt)\
3051 (((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
3053 #define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
3054 PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
3055 /* The number of separate channels (components) in a pixel; 1 for a
3056 * color-mapped image.
3059 #define PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)\
3060 PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_COMPONENT_SIZE,fmt)
3061 /* The size, in bytes, of each component in a pixel; 1 for a color-mapped
3065 #define PNG_IMAGE_PIXEL_SIZE(fmt) PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_SIZE,fmt)
3066 /* The size, in bytes, of a complete pixel; 1 for a color-mapped image. */
3068 /* Information about the whole row, or whole image */
3069 #define PNG_IMAGE_ROW_STRIDE(image)\
3070 (PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
3071 /* Return the total number of components in a single row of the image; this
3072 * is the minimum 'row stride', the minimum count of components between each
3073 * row. For a color-mapped image this is the minimum number of bytes in a
3077 #define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
3078 (PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
3079 /* Return the size, in bytes, of an image buffer given a png_image and a row
3080 * stride - the number of components to leave space for in each row.
3083 #define PNG_IMAGE_SIZE(image)\
3084 PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
3085 /* Return the size, in bytes, of the image in memory given just a png_image;
3086 * the row stride is the minimum stride required for the image.
3089 #define PNG_IMAGE_COLORMAP_SIZE(image)\
3090 (PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
3091 /* Return the size, in bytes, of the color-map of this image. If the image
3092 * format is not a color-map format this will return a size sufficient for
3093 * 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
3094 * you don't want to allocate a color-map in this case.
3099 * Flags containing additional information about the image are held in the
3100 * 'flags' field of png_image.
3102 #define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
3103 /* This indicates the the RGB values of the in-memory bitmap do not
3104 * correspond to the red, green and blue end-points defined by sRGB.
3107 #define PNG_IMAGE_FLAG_FAST 0x02
3108 /* On write emphasise speed over compression; the resultant PNG file will be
3109 * larger but will be produced significantly faster, particular for large
3110 * images. Do not use this option for images which will be distributed, only
3111 * used it when producing intermediate files that will be read back in
3112 * repeatedly. For a typical 24-bit image the option will double the read
3113 * speed at the cost of increasing the image size by 25%, however for many
3114 * more compressible images the PNG file can be 10 times larger with only a
3115 * slight speed gain.
3118 #define PNG_IMAGE_FLAG_16BIT_sRGB 0x04
3119 /* On read if the image is a 16-bit per component image and there is no gAMA
3120 * or sRGB chunk assume that the components are sRGB encoded. Notice that
3121 * images output by the simplified API always have gamma information; setting
3122 * this flag only affects the interpretation of 16-bit images from an
3123 * external source. It is recommended that the application expose this flag
3124 * to the user; the user can normally easily recognize the difference between
3125 * linear and sRGB encoding. This flag has no effect on write - the data
3126 * passed to the write APIs must have the correct encoding (as defined
3129 * If the flag is not set (the default) input 16-bit per component data is
3130 * assumed to be linear.
3132 * NOTE: the flag can only be set after the png_image_begin_read_ call,
3133 * because that call initializes the 'flags' field.
3136 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
3140 * The png_image passed to the read APIs must have been initialized by setting
3141 * the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
3143 #ifdef PNG_STDIO_SUPPORTED
3144 PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
3145 const char *file_name));
3146 /* The named file is opened for read and the image header is filled in
3147 * from the PNG header in the file.
3150 PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
3152 /* The PNG header is read from the stdio FILE object. */
3153 #endif /* PNG_STDIO_SUPPORTED */
3155 PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
3156 png_const_voidp memory, png_size_t size));
3157 /* The PNG header is read from the given memory buffer. */
3159 PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
3160 png_const_colorp background, void *buffer, png_int_32 row_stride,
3162 /* Finish reading the image into the supplied buffer and clean up the
3163 * png_image structure.
3165 * row_stride is the step, in byte or 2-byte units as appropriate,
3166 * between adjacent rows. A positive stride indicates that the top-most row
3167 * is first in the buffer - the normal top-down arrangement. A negative
3168 * stride indicates that the bottom-most row is first in the buffer.
3170 * background need only be supplied if an alpha channel must be removed from
3171 * a png_byte format and the removal is to be done by compositing on a solid
3172 * color; otherwise it may be NULL and any composition will be done directly
3173 * onto the buffer. The value is an sRGB color to use for the background,
3174 * for grayscale output the green channel is used.
3176 * background must be supplied when an alpha channel must be removed from a
3177 * single byte color-mapped output format, in other words if:
3179 * 1) The original format from png_image_begin_read_from_* had
3180 * PNG_FORMAT_FLAG_ALPHA set.
3181 * 2) The format set by the application does not.
3182 * 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
3183 * PNG_FORMAT_FLAG_LINEAR *not* set.
3185 * For linear output removing the alpha channel is always done by compositing
3186 * on black and background is ignored.
3188 * colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set. It must
3189 * be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
3190 * image->colormap_entries will be updated to the actual number of entries
3191 * written to the colormap; this may be less than the original value.
3194 PNG_EXPORT(238, void, png_image_free, (png_imagep image));
3195 /* Free any data allocated by libpng in image->opaque, setting the pointer to
3196 * NULL. May be called at any time after the structure is initialized.
3198 #endif /* PNG_SIMPLIFIED_READ_SUPPORTED */
3200 #ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
3201 #ifdef PNG_STDIO_SUPPORTED
3204 * For write you must initialize a png_image structure to describe the image to
3205 * be written. To do this use memset to set the whole structure to 0 then
3206 * initialize fields describing your image.
3208 * version: must be set to PNG_IMAGE_VERSION
3209 * opaque: must be initialized to NULL
3210 * width: image width in pixels
3211 * height: image height in rows
3212 * format: the format of the data (image and color-map) you wish to write
3213 * flags: set to 0 unless one of the defined flags applies; set
3214 * PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
3215 * values do not correspond to the colors in sRGB.
3216 * colormap_entries: set to the number of entries in the color-map (0 to 256)
3218 PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
3219 const char *file, int convert_to_8bit, const void *buffer,
3220 png_int_32 row_stride, const void *colormap));
3221 /* Write the image to the named file. */
3223 PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
3224 int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
3225 const void *colormap));
3226 /* Write the image to the given (FILE*). */
3228 /* With both write APIs if image is in one of the linear formats with 16-bit
3229 * data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
3230 * gamma encoded according to the sRGB specification, otherwise a 16-bit linear
3231 * encoded PNG file is written.
3233 * With color-mapped data formats the colormap parameter point to a color-map
3234 * with at least image->colormap_entries encoded in the specified format. If
3235 * the format is linear the written PNG color-map will be converted to sRGB
3236 * regardless of the convert_to_8_bit flag.
3238 * With all APIs row_stride is handled as in the read APIs - it is the spacing
3239 * from one row to the next in component sized units (1 or 2 bytes) and if
3240 * negative indicates a bottom-up row layout in the buffer.
3242 * Note that the write API does not support interlacing or sub-8-bit pixels.
3244 #endif /* PNG_STDIO_SUPPORTED */
3245 #endif /* PNG_SIMPLIFIED_WRITE_SUPPORTED */
3246 /*******************************************************************************
3247 * END OF SIMPLIFIED API
3248 ******************************************************************************/
3250 #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
3251 PNG_EXPORT(242, void, png_set_check_for_invalid_index,
3252 (png_structrp png_ptr, int allowed));
3253 # ifdef PNG_GET_PALETTE_MAX_SUPPORTED
3254 PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
3255 png_const_infop info_ptr));
3257 #endif /* CHECK_FOR_INVALID_INDEX */
3259 /*******************************************************************************
3260 * IMPLEMENTATION OPTIONS
3261 *******************************************************************************
3263 * Support for arbitrary implementation-specific optimizations. The API allows
3264 * particular options to be turned on or off. 'Option' is the number of the
3265 * option and 'onoff' is 0 (off) or non-0 (on). The value returned is given
3266 * by the PNG_OPTION_ defines below.
3268 * HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
3269 * are detected at run time, however sometimes it may be impossible
3270 * to do this in user mode, in which case it is necessary to discover
3271 * the capabilities in an OS specific way. Such capabilities are
3272 * listed here when libpng has support for them and must be turned
3273 * ON by the application if present.
3275 * SOFTWARE: sometimes software optimizations actually result in performance
3276 * decrease on some architectures or systems, or with some sets of
3277 * PNG images. 'Software' options allow such optimizations to be
3278 * selected at run time.
3280 #ifdef PNG_SET_OPTION_SUPPORTED
3281 #ifdef PNG_ARM_NEON_API_SUPPORTED
3282 # define PNG_ARM_NEON 0 /* HARDWARE: ARM Neon SIMD instructions supported */
3284 #define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
3285 #define PNG_OPTION_NEXT 4 /* Next option - numbers must be even */
3287 /* Return values: NOTE: there are four values and 'off' is *not* zero */
3288 #define PNG_OPTION_UNSET 0 /* Unset - defaults to off */
3289 #define PNG_OPTION_INVALID 1 /* Option number out of range */
3290 #define PNG_OPTION_OFF 2
3291 #define PNG_OPTION_ON 3
3293 PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
3297 /*******************************************************************************
3298 * END OF HARDWARE OPTIONS
3299 ******************************************************************************/
3301 /* Maintainer: Put new public prototypes here ^, in libpng.3, and project
3302 * defs, scripts/pnglibconf.h, and scripts/pnglibconf.h.prebuilt
3305 /* The last ordinal number (this is the *last* one already used; the next
3306 * one to use is one more than this.) Maintainer, remember to add an entry to
3307 * scripts/symbols.def as well.
3309 #ifdef PNG_EXPORT_LAST_ORDINAL
3310 PNG_EXPORT_LAST_ORDINAL(244);
3317 #endif /* PNG_VERSION_INFO_ONLY */
3318 /* Do not put anything past this line */
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