1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation. Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 */
24
25 /* pngread.c - read a PNG file
26 *
27 * This file is available under and governed by the GNU General Public
28 * License version 2 only, as published by the Free Software Foundation.
29 * However, the following notice accompanied the original version of this
30 * file and, per its terms, should not be removed:
31 *
32 * Last changed in libpng 1.6.23 [June 9, 2016]
33 * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
34 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
35 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
36 *
37 * This code is released under the libpng license.
38 * For conditions of distribution and use, see the disclaimer
39 * and license in png.h
40 *
41 * This file contains routines that an application calls directly to
42 * read a PNG file or stream.
43 */
44
45 #include "pngpriv.h"
46 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
47 # include <errno.h>
48 #endif
49
50 #ifdef PNG_READ_SUPPORTED
51
52 /* Create a PNG structure for reading, and allocate any memory needed. */
53 PNG_FUNCTION(png_structp,PNGAPI
54 png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
55 png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
56 {
57 #ifndef PNG_USER_MEM_SUPPORTED
58 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
59 error_fn, warn_fn, NULL, NULL, NULL);
60 #else
61 return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
62 warn_fn, NULL, NULL, NULL);
63 }
64
65 /* Alternate create PNG structure for reading, and allocate any memory
66 * needed.
67 */
68 PNG_FUNCTION(png_structp,PNGAPI
69 png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
70 png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
71 png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
72 {
73 png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
74 error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
75 #endif /* USER_MEM */
76
77 if (png_ptr != NULL)
78 {
79 png_ptr->mode = PNG_IS_READ_STRUCT;
80
81 /* Added in libpng-1.6.0; this can be used to detect a read structure if
82 * required (it will be zero in a write structure.)
83 */
84 # ifdef PNG_SEQUENTIAL_READ_SUPPORTED
85 png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
86 # endif
87
88 # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
89 png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
90
91 /* In stable builds only warn if an application error can be completely
92 * handled.
93 */
94 # if PNG_RELEASE_BUILD
95 png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
96 # endif
97 # endif
98
99 /* TODO: delay this, it can be done in png_init_io (if the app doesn't
100 * do it itself) avoiding setting the default function if it is not
101 * required.
102 */
103 png_set_read_fn(png_ptr, NULL, NULL);
104 }
105
106 return png_ptr;
107 }
108
109
110 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
111 /* Read the information before the actual image data. This has been
112 * changed in v0.90 to allow reading a file that already has the magic
113 * bytes read from the stream. You can tell libpng how many bytes have
114 * been read from the beginning of the stream (up to the maximum of 8)
115 * via png_set_sig_bytes(), and we will only check the remaining bytes
116 * here. The application can then have access to the signature bytes we
117 * read if it is determined that this isn't a valid PNG file.
118 */
119 void PNGAPI
120 png_read_info(png_structrp png_ptr, png_inforp info_ptr)
121 {
122 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
123 int keep;
124 #endif
125
126 png_debug(1, "in png_read_info");
127
128 if (png_ptr == NULL || info_ptr == NULL)
129 return;
130
131 /* Read and check the PNG file signature. */
132 png_read_sig(png_ptr, info_ptr);
133
134 for (;;)
135 {
136 png_uint_32 length = png_read_chunk_header(png_ptr);
137 png_uint_32 chunk_name = png_ptr->chunk_name;
138
139 /* IDAT logic needs to happen here to simplify getting the two flags
140 * right.
141 */
142 if (chunk_name == png_IDAT)
143 {
144 if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
145 png_chunk_error(png_ptr, "Missing IHDR before IDAT");
146
147 else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
148 (png_ptr->mode & PNG_HAVE_PLTE) == 0)
149 png_chunk_error(png_ptr, "Missing PLTE before IDAT");
150
151 else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
152 png_chunk_benign_error(png_ptr, "Too many IDATs found");
153
154 png_ptr->mode |= PNG_HAVE_IDAT;
155 }
156
157 else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
158 {
159 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
160 png_ptr->mode |= PNG_AFTER_IDAT;
161 }
162
163 /* This should be a binary subdivision search or a hash for
164 * matching the chunk name rather than a linear search.
165 */
166 if (chunk_name == png_IHDR)
167 png_handle_IHDR(png_ptr, info_ptr, length);
168
169 else if (chunk_name == png_IEND)
170 png_handle_IEND(png_ptr, info_ptr, length);
171
172 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
173 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
174 {
175 png_handle_unknown(png_ptr, info_ptr, length, keep);
176
177 if (chunk_name == png_PLTE)
178 png_ptr->mode |= PNG_HAVE_PLTE;
179
180 else if (chunk_name == png_IDAT)
181 {
182 png_ptr->idat_size = 0; /* It has been consumed */
183 break;
184 }
185 }
186 #endif
187 else if (chunk_name == png_PLTE)
188 png_handle_PLTE(png_ptr, info_ptr, length);
189
190 else if (chunk_name == png_IDAT)
191 {
192 png_ptr->idat_size = length;
193 break;
194 }
195
196 #ifdef PNG_READ_bKGD_SUPPORTED
197 else if (chunk_name == png_bKGD)
198 png_handle_bKGD(png_ptr, info_ptr, length);
199 #endif
200
201 #ifdef PNG_READ_cHRM_SUPPORTED
202 else if (chunk_name == png_cHRM)
203 png_handle_cHRM(png_ptr, info_ptr, length);
204 #endif
205
206 #ifdef PNG_READ_gAMA_SUPPORTED
207 else if (chunk_name == png_gAMA)
208 png_handle_gAMA(png_ptr, info_ptr, length);
209 #endif
210
211 #ifdef PNG_READ_hIST_SUPPORTED
212 else if (chunk_name == png_hIST)
213 png_handle_hIST(png_ptr, info_ptr, length);
214 #endif
215
216 #ifdef PNG_READ_oFFs_SUPPORTED
217 else if (chunk_name == png_oFFs)
218 png_handle_oFFs(png_ptr, info_ptr, length);
219 #endif
220
221 #ifdef PNG_READ_pCAL_SUPPORTED
222 else if (chunk_name == png_pCAL)
223 png_handle_pCAL(png_ptr, info_ptr, length);
224 #endif
225
226 #ifdef PNG_READ_sCAL_SUPPORTED
227 else if (chunk_name == png_sCAL)
228 png_handle_sCAL(png_ptr, info_ptr, length);
229 #endif
230
231 #ifdef PNG_READ_pHYs_SUPPORTED
232 else if (chunk_name == png_pHYs)
233 png_handle_pHYs(png_ptr, info_ptr, length);
234 #endif
235
236 #ifdef PNG_READ_sBIT_SUPPORTED
237 else if (chunk_name == png_sBIT)
238 png_handle_sBIT(png_ptr, info_ptr, length);
239 #endif
240
241 #ifdef PNG_READ_sRGB_SUPPORTED
242 else if (chunk_name == png_sRGB)
243 png_handle_sRGB(png_ptr, info_ptr, length);
244 #endif
245
246 #ifdef PNG_READ_iCCP_SUPPORTED
247 else if (chunk_name == png_iCCP)
248 png_handle_iCCP(png_ptr, info_ptr, length);
249 #endif
250
251 #ifdef PNG_READ_sPLT_SUPPORTED
252 else if (chunk_name == png_sPLT)
253 png_handle_sPLT(png_ptr, info_ptr, length);
254 #endif
255
256 #ifdef PNG_READ_tEXt_SUPPORTED
257 else if (chunk_name == png_tEXt)
258 png_handle_tEXt(png_ptr, info_ptr, length);
259 #endif
260
261 #ifdef PNG_READ_tIME_SUPPORTED
262 else if (chunk_name == png_tIME)
263 png_handle_tIME(png_ptr, info_ptr, length);
264 #endif
265
266 #ifdef PNG_READ_tRNS_SUPPORTED
267 else if (chunk_name == png_tRNS)
268 png_handle_tRNS(png_ptr, info_ptr, length);
269 #endif
270
271 #ifdef PNG_READ_zTXt_SUPPORTED
272 else if (chunk_name == png_zTXt)
273 png_handle_zTXt(png_ptr, info_ptr, length);
274 #endif
275
276 #ifdef PNG_READ_iTXt_SUPPORTED
277 else if (chunk_name == png_iTXt)
278 png_handle_iTXt(png_ptr, info_ptr, length);
279 #endif
280
281 else
282 png_handle_unknown(png_ptr, info_ptr, length,
283 PNG_HANDLE_CHUNK_AS_DEFAULT);
284 }
285 }
286 #endif /* SEQUENTIAL_READ */
287
288 /* Optional call to update the users info_ptr structure */
289 void PNGAPI
290 png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
291 {
292 png_debug(1, "in png_read_update_info");
293
294 if (png_ptr != NULL)
295 {
296 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
297 {
298 png_read_start_row(png_ptr);
299
300 # ifdef PNG_READ_TRANSFORMS_SUPPORTED
301 png_read_transform_info(png_ptr, info_ptr);
302 # else
303 PNG_UNUSED(info_ptr)
304 # endif
305 }
306
307 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
308 else
309 png_app_error(png_ptr,
310 "png_read_update_info/png_start_read_image: duplicate call");
311 }
312 }
313
314 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
315 /* Initialize palette, background, etc, after transformations
316 * are set, but before any reading takes place. This allows
317 * the user to obtain a gamma-corrected palette, for example.
318 * If the user doesn't call this, we will do it ourselves.
319 */
320 void PNGAPI
321 png_start_read_image(png_structrp png_ptr)
322 {
323 png_debug(1, "in png_start_read_image");
324
325 if (png_ptr != NULL)
326 {
327 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
328 png_read_start_row(png_ptr);
329
330 /* New in 1.6.0 this avoids the bug of doing the initializations twice */
331 else
332 png_app_error(png_ptr,
333 "png_start_read_image/png_read_update_info: duplicate call");
334 }
335 }
336 #endif /* SEQUENTIAL_READ */
337
338 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
339 #ifdef PNG_MNG_FEATURES_SUPPORTED
340 /* Undoes intrapixel differencing,
341 * NOTE: this is apparently only supported in the 'sequential' reader.
342 */
343 static void
344 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
345 {
346 png_debug(1, "in png_do_read_intrapixel");
347
348 if (
349 (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
350 {
351 int bytes_per_pixel;
352 png_uint_32 row_width = row_info->width;
353
354 if (row_info->bit_depth == 8)
355 {
356 png_bytep rp;
357 png_uint_32 i;
358
359 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
360 bytes_per_pixel = 3;
361
362 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
363 bytes_per_pixel = 4;
364
365 else
366 return;
367
368 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
369 {
370 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
371 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
372 }
373 }
374 else if (row_info->bit_depth == 16)
375 {
376 png_bytep rp;
377 png_uint_32 i;
378
379 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
380 bytes_per_pixel = 6;
381
382 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
383 bytes_per_pixel = 8;
384
385 else
386 return;
387
388 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
389 {
390 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
391 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
392 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
393 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
394 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
395 *(rp ) = (png_byte)((red >> 8) & 0xff);
396 *(rp + 1) = (png_byte)(red & 0xff);
397 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
398 *(rp + 5) = (png_byte)(blue & 0xff);
399 }
400 }
401 }
402 }
403 #endif /* MNG_FEATURES */
404
405 void PNGAPI
406 png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
407 {
408 png_row_info row_info;
409
410 if (png_ptr == NULL)
411 return;
412
413 png_debug2(1, "in png_read_row (row %lu, pass %d)",
414 (unsigned long)png_ptr->row_number, png_ptr->pass);
415
416 /* png_read_start_row sets the information (in particular iwidth) for this
417 * interlace pass.
418 */
419 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
420 png_read_start_row(png_ptr);
421
422 /* 1.5.6: row_info moved out of png_struct to a local here. */
423 row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
424 row_info.color_type = png_ptr->color_type;
425 row_info.bit_depth = png_ptr->bit_depth;
426 row_info.channels = png_ptr->channels;
427 row_info.pixel_depth = png_ptr->pixel_depth;
428 row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
429
430 #ifdef PNG_WARNINGS_SUPPORTED
431 if (png_ptr->row_number == 0 && png_ptr->pass == 0)
432 {
433 /* Check for transforms that have been set but were defined out */
434 #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
435 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
436 png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
437 #endif
438
439 #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
440 if ((png_ptr->transformations & PNG_FILLER) != 0)
441 png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
442 #endif
443
444 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
445 !defined(PNG_READ_PACKSWAP_SUPPORTED)
446 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
447 png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
448 #endif
449
450 #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
451 if ((png_ptr->transformations & PNG_PACK) != 0)
452 png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
453 #endif
454
455 #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
456 if ((png_ptr->transformations & PNG_SHIFT) != 0)
457 png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
458 #endif
459
460 #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
461 if ((png_ptr->transformations & PNG_BGR) != 0)
462 png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
463 #endif
464
465 #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
466 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
467 png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
468 #endif
469 }
470 #endif /* WARNINGS */
471
472 #ifdef PNG_READ_INTERLACING_SUPPORTED
473 /* If interlaced and we do not need a new row, combine row and return.
474 * Notice that the pixels we have from previous rows have been transformed
475 * already; we can only combine like with like (transformed or
476 * untransformed) and, because of the libpng API for interlaced images, this
477 * means we must transform before de-interlacing.
478 */
479 if (png_ptr->interlaced != 0 &&
480 (png_ptr->transformations & PNG_INTERLACE) != 0)
481 {
482 switch (png_ptr->pass)
483 {
484 case 0:
485 if (png_ptr->row_number & 0x07)
486 {
487 if (dsp_row != NULL)
488 png_combine_row(png_ptr, dsp_row, 1/*display*/);
489 png_read_finish_row(png_ptr);
490 return;
491 }
492 break;
493
494 case 1:
495 if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
496 {
497 if (dsp_row != NULL)
498 png_combine_row(png_ptr, dsp_row, 1/*display*/);
499
500 png_read_finish_row(png_ptr);
501 return;
502 }
503 break;
504
505 case 2:
506 if ((png_ptr->row_number & 0x07) != 4)
507 {
508 if (dsp_row != NULL && (png_ptr->row_number & 4))
509 png_combine_row(png_ptr, dsp_row, 1/*display*/);
510
511 png_read_finish_row(png_ptr);
512 return;
513 }
514 break;
515
516 case 3:
517 if ((png_ptr->row_number & 3) || png_ptr->width < 3)
518 {
519 if (dsp_row != NULL)
520 png_combine_row(png_ptr, dsp_row, 1/*display*/);
521
522 png_read_finish_row(png_ptr);
523 return;
524 }
525 break;
526
527 case 4:
528 if ((png_ptr->row_number & 3) != 2)
529 {
530 if (dsp_row != NULL && (png_ptr->row_number & 2))
531 png_combine_row(png_ptr, dsp_row, 1/*display*/);
532
533 png_read_finish_row(png_ptr);
534 return;
535 }
536 break;
537
538 case 5:
539 if ((png_ptr->row_number & 1) || png_ptr->width < 2)
540 {
541 if (dsp_row != NULL)
542 png_combine_row(png_ptr, dsp_row, 1/*display*/);
543
544 png_read_finish_row(png_ptr);
545 return;
546 }
547 break;
548
549 default:
550 case 6:
551 if ((png_ptr->row_number & 1) == 0)
552 {
553 png_read_finish_row(png_ptr);
554 return;
555 }
556 break;
557 }
558 }
559 #endif
560
561 if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
562 png_error(png_ptr, "Invalid attempt to read row data");
563
564 /* Fill the row with IDAT data: */
565 png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
566
567 if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
568 {
569 if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
570 png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
571 png_ptr->prev_row + 1, png_ptr->row_buf[0]);
572 else
573 png_error(png_ptr, "bad adaptive filter value");
574 }
575
576 /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
577 * 1.5.6, while the buffer really is this big in current versions of libpng
578 * it may not be in the future, so this was changed just to copy the
579 * interlaced count:
580 */
581 memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
582
583 #ifdef PNG_MNG_FEATURES_SUPPORTED
584 if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
585 (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
586 {
587 /* Intrapixel differencing */
588 png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
589 }
590 #endif
591
592 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
593 if (png_ptr->transformations)
594 png_do_read_transformations(png_ptr, &row_info);
595 #endif
596
597 /* The transformed pixel depth should match the depth now in row_info. */
598 if (png_ptr->transformed_pixel_depth == 0)
599 {
600 png_ptr->transformed_pixel_depth = row_info.pixel_depth;
601 if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
602 png_error(png_ptr, "sequential row overflow");
603 }
604
605 else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
606 png_error(png_ptr, "internal sequential row size calculation error");
607
608 #ifdef PNG_READ_INTERLACING_SUPPORTED
609 /* Expand interlaced rows to full size */
610 if (png_ptr->interlaced != 0 &&
611 (png_ptr->transformations & PNG_INTERLACE) != 0)
612 {
613 if (png_ptr->pass < 6)
614 png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
615 png_ptr->transformations);
616
617 if (dsp_row != NULL)
618 png_combine_row(png_ptr, dsp_row, 1/*display*/);
619
620 if (row != NULL)
621 png_combine_row(png_ptr, row, 0/*row*/);
622 }
623
624 else
625 #endif
626 {
627 if (row != NULL)
628 png_combine_row(png_ptr, row, -1/*ignored*/);
629
630 if (dsp_row != NULL)
631 png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
632 }
633 png_read_finish_row(png_ptr);
634
635 if (png_ptr->read_row_fn != NULL)
636 (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
637
638 }
639 #endif /* SEQUENTIAL_READ */
640
641 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
642 /* Read one or more rows of image data. If the image is interlaced,
643 * and png_set_interlace_handling() has been called, the rows need to
644 * contain the contents of the rows from the previous pass. If the
645 * image has alpha or transparency, and png_handle_alpha()[*] has been
646 * called, the rows contents must be initialized to the contents of the
647 * screen.
648 *
649 * "row" holds the actual image, and pixels are placed in it
650 * as they arrive. If the image is displayed after each pass, it will
651 * appear to "sparkle" in. "display_row" can be used to display a
652 * "chunky" progressive image, with finer detail added as it becomes
653 * available. If you do not want this "chunky" display, you may pass
654 * NULL for display_row. If you do not want the sparkle display, and
655 * you have not called png_handle_alpha(), you may pass NULL for rows.
656 * If you have called png_handle_alpha(), and the image has either an
657 * alpha channel or a transparency chunk, you must provide a buffer for
658 * rows. In this case, you do not have to provide a display_row buffer
659 * also, but you may. If the image is not interlaced, or if you have
660 * not called png_set_interlace_handling(), the display_row buffer will
661 * be ignored, so pass NULL to it.
662 *
663 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
664 */
665
666 void PNGAPI
667 png_read_rows(png_structrp png_ptr, png_bytepp row,
668 png_bytepp display_row, png_uint_32 num_rows)
669 {
670 png_uint_32 i;
671 png_bytepp rp;
672 png_bytepp dp;
673
674 png_debug(1, "in png_read_rows");
675
676 if (png_ptr == NULL)
677 return;
678
679 rp = row;
680 dp = display_row;
681 if (rp != NULL && dp != NULL)
682 for (i = 0; i < num_rows; i++)
683 {
684 png_bytep rptr = *rp++;
685 png_bytep dptr = *dp++;
686
687 png_read_row(png_ptr, rptr, dptr);
688 }
689
690 else if (rp != NULL)
691 for (i = 0; i < num_rows; i++)
692 {
693 png_bytep rptr = *rp;
694 png_read_row(png_ptr, rptr, NULL);
695 rp++;
696 }
697
698 else if (dp != NULL)
699 for (i = 0; i < num_rows; i++)
700 {
701 png_bytep dptr = *dp;
702 png_read_row(png_ptr, NULL, dptr);
703 dp++;
704 }
705 }
706 #endif /* SEQUENTIAL_READ */
707
708 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
709 /* Read the entire image. If the image has an alpha channel or a tRNS
710 * chunk, and you have called png_handle_alpha()[*], you will need to
711 * initialize the image to the current image that PNG will be overlaying.
712 * We set the num_rows again here, in case it was incorrectly set in
713 * png_read_start_row() by a call to png_read_update_info() or
714 * png_start_read_image() if png_set_interlace_handling() wasn't called
715 * prior to either of these functions like it should have been. You can
716 * only call this function once. If you desire to have an image for
717 * each pass of a interlaced image, use png_read_rows() instead.
718 *
719 * [*] png_handle_alpha() does not exist yet, as of this version of libpng
720 */
721 void PNGAPI
722 png_read_image(png_structrp png_ptr, png_bytepp image)
723 {
724 png_uint_32 i, image_height;
725 int pass, j;
726 png_bytepp rp;
727
728 png_debug(1, "in png_read_image");
729
730 if (png_ptr == NULL)
731 return;
732
733 #ifdef PNG_READ_INTERLACING_SUPPORTED
734 if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
735 {
736 pass = png_set_interlace_handling(png_ptr);
737 /* And make sure transforms are initialized. */
738 png_start_read_image(png_ptr);
739 }
740 else
741 {
742 if (png_ptr->interlaced != 0 &&
743 (png_ptr->transformations & PNG_INTERLACE) == 0)
744 {
745 /* Caller called png_start_read_image or png_read_update_info without
746 * first turning on the PNG_INTERLACE transform. We can fix this here,
747 * but the caller should do it!
748 */
749 png_warning(png_ptr, "Interlace handling should be turned on when "
750 "using png_read_image");
751 /* Make sure this is set correctly */
752 png_ptr->num_rows = png_ptr->height;
753 }
754
755 /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
756 * the above error case.
757 */
758 pass = png_set_interlace_handling(png_ptr);
759 }
760 #else
761 if (png_ptr->interlaced)
762 png_error(png_ptr,
763 "Cannot read interlaced image -- interlace handler disabled");
764
765 pass = 1;
766 #endif
767
768 image_height=png_ptr->height;
769
770 for (j = 0; j < pass; j++)
771 {
772 rp = image;
773 for (i = 0; i < image_height; i++)
774 {
775 png_read_row(png_ptr, *rp, NULL);
776 rp++;
777 }
778 }
779 }
780 #endif /* SEQUENTIAL_READ */
781
782 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
783 /* Read the end of the PNG file. Will not read past the end of the
784 * file, will verify the end is accurate, and will read any comments
785 * or time information at the end of the file, if info is not NULL.
786 */
787 void PNGAPI
788 png_read_end(png_structrp png_ptr, png_inforp info_ptr)
789 {
790 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
791 int keep;
792 #endif
793
794 png_debug(1, "in png_read_end");
795
796 if (png_ptr == NULL)
797 return;
798
799 /* If png_read_end is called in the middle of reading the rows there may
800 * still be pending IDAT data and an owned zstream. Deal with this here.
801 */
802 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
803 if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
804 #endif
805 png_read_finish_IDAT(png_ptr);
806
807 #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
808 /* Report invalid palette index; added at libng-1.5.10 */
809 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
810 png_ptr->num_palette_max > png_ptr->num_palette)
811 png_benign_error(png_ptr, "Read palette index exceeding num_palette");
812 #endif
813
814 do
815 {
816 png_uint_32 length = png_read_chunk_header(png_ptr);
817 png_uint_32 chunk_name = png_ptr->chunk_name;
818
819 if (chunk_name != png_IDAT)
820 png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
821
822 if (chunk_name == png_IEND)
823 png_handle_IEND(png_ptr, info_ptr, length);
824
825 else if (chunk_name == png_IHDR)
826 png_handle_IHDR(png_ptr, info_ptr, length);
827
828 else if (info_ptr == NULL)
829 png_crc_finish(png_ptr, length);
830
831 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
832 else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
833 {
834 if (chunk_name == png_IDAT)
835 {
836 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
837 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
838 png_benign_error(png_ptr, ".Too many IDATs found");
839 }
840 png_handle_unknown(png_ptr, info_ptr, length, keep);
841 if (chunk_name == png_PLTE)
842 png_ptr->mode |= PNG_HAVE_PLTE;
843 }
844 #endif
845
846 else if (chunk_name == png_IDAT)
847 {
848 /* Zero length IDATs are legal after the last IDAT has been
849 * read, but not after other chunks have been read. 1.6 does not
850 * always read all the deflate data; specifically it cannot be relied
851 * upon to read the Adler32 at the end. If it doesn't ignore IDAT
852 * chunks which are longer than zero as well:
853 */
854 if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
855 || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
856 png_benign_error(png_ptr, "..Too many IDATs found");
857
858 png_crc_finish(png_ptr, length);
859 }
860 else if (chunk_name == png_PLTE)
861 png_handle_PLTE(png_ptr, info_ptr, length);
862
863 #ifdef PNG_READ_bKGD_SUPPORTED
864 else if (chunk_name == png_bKGD)
865 png_handle_bKGD(png_ptr, info_ptr, length);
866 #endif
867
868 #ifdef PNG_READ_cHRM_SUPPORTED
869 else if (chunk_name == png_cHRM)
870 png_handle_cHRM(png_ptr, info_ptr, length);
871 #endif
872
873 #ifdef PNG_READ_gAMA_SUPPORTED
874 else if (chunk_name == png_gAMA)
875 png_handle_gAMA(png_ptr, info_ptr, length);
876 #endif
877
878 #ifdef PNG_READ_hIST_SUPPORTED
879 else if (chunk_name == png_hIST)
880 png_handle_hIST(png_ptr, info_ptr, length);
881 #endif
882
883 #ifdef PNG_READ_oFFs_SUPPORTED
884 else if (chunk_name == png_oFFs)
885 png_handle_oFFs(png_ptr, info_ptr, length);
886 #endif
887
888 #ifdef PNG_READ_pCAL_SUPPORTED
889 else if (chunk_name == png_pCAL)
890 png_handle_pCAL(png_ptr, info_ptr, length);
891 #endif
892
893 #ifdef PNG_READ_sCAL_SUPPORTED
894 else if (chunk_name == png_sCAL)
895 png_handle_sCAL(png_ptr, info_ptr, length);
896 #endif
897
898 #ifdef PNG_READ_pHYs_SUPPORTED
899 else if (chunk_name == png_pHYs)
900 png_handle_pHYs(png_ptr, info_ptr, length);
901 #endif
902
903 #ifdef PNG_READ_sBIT_SUPPORTED
904 else if (chunk_name == png_sBIT)
905 png_handle_sBIT(png_ptr, info_ptr, length);
906 #endif
907
908 #ifdef PNG_READ_sRGB_SUPPORTED
909 else if (chunk_name == png_sRGB)
910 png_handle_sRGB(png_ptr, info_ptr, length);
911 #endif
912
913 #ifdef PNG_READ_iCCP_SUPPORTED
914 else if (chunk_name == png_iCCP)
915 png_handle_iCCP(png_ptr, info_ptr, length);
916 #endif
917
918 #ifdef PNG_READ_sPLT_SUPPORTED
919 else if (chunk_name == png_sPLT)
920 png_handle_sPLT(png_ptr, info_ptr, length);
921 #endif
922
923 #ifdef PNG_READ_tEXt_SUPPORTED
924 else if (chunk_name == png_tEXt)
925 png_handle_tEXt(png_ptr, info_ptr, length);
926 #endif
927
928 #ifdef PNG_READ_tIME_SUPPORTED
929 else if (chunk_name == png_tIME)
930 png_handle_tIME(png_ptr, info_ptr, length);
931 #endif
932
933 #ifdef PNG_READ_tRNS_SUPPORTED
934 else if (chunk_name == png_tRNS)
935 png_handle_tRNS(png_ptr, info_ptr, length);
936 #endif
937
938 #ifdef PNG_READ_zTXt_SUPPORTED
939 else if (chunk_name == png_zTXt)
940 png_handle_zTXt(png_ptr, info_ptr, length);
941 #endif
942
943 #ifdef PNG_READ_iTXt_SUPPORTED
944 else if (chunk_name == png_iTXt)
945 png_handle_iTXt(png_ptr, info_ptr, length);
946 #endif
947
948 else
949 png_handle_unknown(png_ptr, info_ptr, length,
950 PNG_HANDLE_CHUNK_AS_DEFAULT);
951 } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
952 }
953 #endif /* SEQUENTIAL_READ */
954
955 /* Free all memory used in the read struct */
956 static void
957 png_read_destroy(png_structrp png_ptr)
958 {
959 png_debug(1, "in png_read_destroy");
960
961 #ifdef PNG_READ_GAMMA_SUPPORTED
962 png_destroy_gamma_table(png_ptr);
963 #endif
964
965 png_free(png_ptr, png_ptr->big_row_buf);
966 png_ptr->big_row_buf = NULL;
967 png_free(png_ptr, png_ptr->big_prev_row);
968 png_ptr->big_prev_row = NULL;
969 png_free(png_ptr, png_ptr->read_buffer);
970 png_ptr->read_buffer = NULL;
971
972 #ifdef PNG_READ_QUANTIZE_SUPPORTED
973 png_free(png_ptr, png_ptr->palette_lookup);
974 png_ptr->palette_lookup = NULL;
975 png_free(png_ptr, png_ptr->quantize_index);
976 png_ptr->quantize_index = NULL;
977 #endif
978
979 if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
980 {
981 png_zfree(png_ptr, png_ptr->palette);
982 png_ptr->palette = NULL;
983 }
984 png_ptr->free_me &= ~PNG_FREE_PLTE;
985
986 #if defined(PNG_tRNS_SUPPORTED) || \
987 defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
988 if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
989 {
990 png_free(png_ptr, png_ptr->trans_alpha);
991 png_ptr->trans_alpha = NULL;
992 }
993 png_ptr->free_me &= ~PNG_FREE_TRNS;
994 #endif
995
996 inflateEnd(&png_ptr->zstream);
997
998 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
999 png_free(png_ptr, png_ptr->save_buffer);
1000 png_ptr->save_buffer = NULL;
1001 #endif
1002
1003 #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
1004 defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1005 png_free(png_ptr, png_ptr->unknown_chunk.data);
1006 png_ptr->unknown_chunk.data = NULL;
1007 #endif
1008
1009 #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
1010 png_free(png_ptr, png_ptr->chunk_list);
1011 png_ptr->chunk_list = NULL;
1012 #endif
1013
1014 /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
1015 * callbacks are still set at this point. They are required to complete the
1016 * destruction of the png_struct itself.
1017 */
1018 }
1019
1020 /* Free all memory used by the read */
1021 void PNGAPI
1022 png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
1023 png_infopp end_info_ptr_ptr)
1024 {
1025 png_structrp png_ptr = NULL;
1026
1027 png_debug(1, "in png_destroy_read_struct");
1028
1029 if (png_ptr_ptr != NULL)
1030 png_ptr = *png_ptr_ptr;
1031
1032 if (png_ptr == NULL)
1033 return;
1034
1035 /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
1036 * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1037 * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1038 */
1039 png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1040 png_destroy_info_struct(png_ptr, info_ptr_ptr);
1041
1042 *png_ptr_ptr = NULL;
1043 png_read_destroy(png_ptr);
1044 png_destroy_png_struct(png_ptr);
1045 }
1046
1047 void PNGAPI
1048 png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
1049 {
1050 if (png_ptr == NULL)
1051 return;
1052
1053 png_ptr->read_row_fn = read_row_fn;
1054 }
1055
1056
1057 #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1058 #ifdef PNG_INFO_IMAGE_SUPPORTED
1059 void PNGAPI
1060 png_read_png(png_structrp png_ptr, png_inforp info_ptr,
1061 int transforms,
1062 voidp params)
1063 {
1064 if (png_ptr == NULL || info_ptr == NULL)
1065 return;
1066
1067 /* png_read_info() gives us all of the information from the
1068 * PNG file before the first IDAT (image data chunk).
1069 */
1070 png_read_info(png_ptr, info_ptr);
1071 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1072 png_error(png_ptr, "Image is too high to process with png_read_png()");
1073
1074 /* -------------- image transformations start here ------------------- */
1075 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1076 * is not implemented. This will only happen in de-configured (non-default)
1077 * libpng builds. The results can be unexpected - png_read_png may return
1078 * short or mal-formed rows because the transform is skipped.
1079 */
1080
1081 /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1082 */
1083 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1084 /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1085 * did in earlier versions, while "scale_16" is now more accurate.
1086 */
1087 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1088 png_set_scale_16(png_ptr);
1089 #else
1090 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1091 #endif
1092
1093 /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1094 * latter by doing SCALE first. This is ok and allows apps not to check for
1095 * which is supported to get the right answer.
1096 */
1097 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1098 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1099 png_set_strip_16(png_ptr);
1100 #else
1101 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1102 #endif
1103
1104 /* Strip alpha bytes from the input data without combining with
1105 * the background (not recommended).
1106 */
1107 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1108 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1109 png_set_strip_alpha(png_ptr);
1110 #else
1111 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1112 #endif
1113
1114 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1115 * byte into separate bytes (useful for paletted and grayscale images).
1116 */
1117 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1118 #ifdef PNG_READ_PACK_SUPPORTED
1119 png_set_packing(png_ptr);
1120 #else
1121 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1122 #endif
1123
1124 /* Change the order of packed pixels to least significant bit first
1125 * (not useful if you are using png_set_packing).
1126 */
1127 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1128 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1129 png_set_packswap(png_ptr);
1130 #else
1131 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1132 #endif
1133
1134 /* Expand paletted colors into true RGB triplets
1135 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1136 * Expand paletted or RGB images with transparency to full alpha
1137 * channels so the data will be available as RGBA quartets.
1138 */
1139 if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1140 #ifdef PNG_READ_EXPAND_SUPPORTED
1141 png_set_expand(png_ptr);
1142 #else
1143 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1144 #endif
1145
1146 /* We don't handle background color or gamma transformation or quantizing.
1147 */
1148
1149 /* Invert monochrome files to have 0 as white and 1 as black
1150 */
1151 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1152 #ifdef PNG_READ_INVERT_SUPPORTED
1153 png_set_invert_mono(png_ptr);
1154 #else
1155 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1156 #endif
1157
1158 /* If you want to shift the pixel values from the range [0,255] or
1159 * [0,65535] to the original [0,7] or [0,31], or whatever range the
1160 * colors were originally in:
1161 */
1162 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1163 #ifdef PNG_READ_SHIFT_SUPPORTED
1164 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1165 png_set_shift(png_ptr, &info_ptr->sig_bit);
1166 #else
1167 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1168 #endif
1169
1170 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1171 if ((transforms & PNG_TRANSFORM_BGR) != 0)
1172 #ifdef PNG_READ_BGR_SUPPORTED
1173 png_set_bgr(png_ptr);
1174 #else
1175 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1176 #endif
1177
1178 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1179 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1180 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1181 png_set_swap_alpha(png_ptr);
1182 #else
1183 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1184 #endif
1185
1186 /* Swap bytes of 16-bit files to least significant byte first */
1187 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1188 #ifdef PNG_READ_SWAP_SUPPORTED
1189 png_set_swap(png_ptr);
1190 #else
1191 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1192 #endif
1193
1194 /* Added at libpng-1.2.41 */
1195 /* Invert the alpha channel from opacity to transparency */
1196 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1197 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1198 png_set_invert_alpha(png_ptr);
1199 #else
1200 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1201 #endif
1202
1203 /* Added at libpng-1.2.41 */
1204 /* Expand grayscale image to RGB */
1205 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1206 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1207 png_set_gray_to_rgb(png_ptr);
1208 #else
1209 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1210 #endif
1211
1212 /* Added at libpng-1.5.4 */
1213 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1214 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1215 png_set_expand_16(png_ptr);
1216 #else
1217 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1218 #endif
1219
1220 /* We don't handle adding filler bytes */
1221
1222 /* We use png_read_image and rely on that for interlace handling, but we also
1223 * call png_read_update_info therefore must turn on interlace handling now:
1224 */
1225 (void)png_set_interlace_handling(png_ptr);
1226
1227 /* Optional call to gamma correct and add the background to the palette
1228 * and update info structure. REQUIRED if you are expecting libpng to
1229 * update the palette for you (i.e., you selected such a transform above).
1230 */
1231 png_read_update_info(png_ptr, info_ptr);
1232
1233 /* -------------- image transformations end here ------------------- */
1234
1235 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1236 if (info_ptr->row_pointers == NULL)
1237 {
1238 png_uint_32 iptr;
1239
1240 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1241 info_ptr->height * (sizeof (png_bytep))));
1242
1243 for (iptr=0; iptr<info_ptr->height; iptr++)
1244 info_ptr->row_pointers[iptr] = NULL;
1245
1246 info_ptr->free_me |= PNG_FREE_ROWS;
1247
1248 for (iptr = 0; iptr < info_ptr->height; iptr++)
1249 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1250 png_malloc(png_ptr, info_ptr->rowbytes));
1251 }
1252
1253 png_read_image(png_ptr, info_ptr->row_pointers);
1254 info_ptr->valid |= PNG_INFO_IDAT;
1255
1256 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1257 png_read_end(png_ptr, info_ptr);
1258
1259 PNG_UNUSED(params)
1260 }
1261 #endif /* INFO_IMAGE */
1262 #endif /* SEQUENTIAL_READ */
1263
1264 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1265 /* SIMPLIFIED READ
1266 *
1267 * This code currently relies on the sequential reader, though it could easily
1268 * be made to work with the progressive one.
1269 */
1270 /* Arguments to png_image_finish_read: */
1271
1272 /* Encoding of PNG data (used by the color-map code) */
1273 # define P_NOTSET 0 /* File encoding not yet known */
1274 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1275 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1276 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1277 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1278
1279 /* Color-map processing: after libpng has run on the PNG image further
1280 * processing may be needed to convert the data to color-map indices.
1281 */
1282 #define PNG_CMAP_NONE 0
1283 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1284 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1285 #define PNG_CMAP_RGB 3 /* Process RGB data */
1286 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1287
1288 /* The following document where the background is for each processing case. */
1289 #define PNG_CMAP_NONE_BACKGROUND 256
1290 #define PNG_CMAP_GA_BACKGROUND 231
1291 #define PNG_CMAP_TRANS_BACKGROUND 254
1292 #define PNG_CMAP_RGB_BACKGROUND 256
1293 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1294
1295 typedef struct
1296 {
1297 /* Arguments: */
1298 png_imagep image;
1299 png_voidp buffer;
1300 png_int_32 row_stride;
1301 png_voidp colormap;
1302 png_const_colorp background;
1303 /* Local variables: */
1304 png_voidp local_row;
1305 png_voidp first_row;
1306 ptrdiff_t row_bytes; /* step between rows */
1307 int file_encoding; /* E_ values above */
1308 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1309 int colormap_processing; /* PNG_CMAP_ values above */
1310 } png_image_read_control;
1311
1312 /* Do all the *safe* initialization - 'safe' means that png_error won't be
1313 * called, so setting up the jmp_buf is not required. This means that anything
1314 * called from here must *not* call png_malloc - it has to call png_malloc_warn
1315 * instead so that control is returned safely back to this routine.
1316 */
1317 static int
1318 png_image_read_init(png_imagep image)
1319 {
1320 if (image->opaque == NULL)
1321 {
1322 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1323 png_safe_error, png_safe_warning);
1324
1325 /* And set the rest of the structure to NULL to ensure that the various
1326 * fields are consistent.
1327 */
1328 memset(image, 0, (sizeof *image));
1329 image->version = PNG_IMAGE_VERSION;
1330
1331 if (png_ptr != NULL)
1332 {
1333 png_infop info_ptr = png_create_info_struct(png_ptr);
1334
1335 if (info_ptr != NULL)
1336 {
1337 png_controlp control = png_voidcast(png_controlp,
1338 png_malloc_warn(png_ptr, (sizeof *control)));
1339
1340 if (control != NULL)
1341 {
1342 memset(control, 0, (sizeof *control));
1343
1344 control->png_ptr = png_ptr;
1345 control->info_ptr = info_ptr;
1346 control->for_write = 0;
1347
1348 image->opaque = control;
1349 return 1;
1350 }
1351
1352 /* Error clean up */
1353 png_destroy_info_struct(png_ptr, &info_ptr);
1354 }
1355
1356 png_destroy_read_struct(&png_ptr, NULL, NULL);
1357 }
1358
1359 return png_image_error(image, "png_image_read: out of memory");
1360 }
1361
1362 return png_image_error(image, "png_image_read: opaque pointer not NULL");
1363 }
1364
1365 /* Utility to find the base format of a PNG file from a png_struct. */
1366 static png_uint_32
1367 png_image_format(png_structrp png_ptr)
1368 {
1369 png_uint_32 format = 0;
1370
1371 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1372 format |= PNG_FORMAT_FLAG_COLOR;
1373
1374 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1375 format |= PNG_FORMAT_FLAG_ALPHA;
1376
1377 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1378 * sets the png_struct fields; that's all we are interested in here. The
1379 * precise interaction with an app call to png_set_tRNS and PNG file reading
1380 * is unclear.
1381 */
1382 else if (png_ptr->num_trans > 0)
1383 format |= PNG_FORMAT_FLAG_ALPHA;
1384
1385 if (png_ptr->bit_depth == 16)
1386 format |= PNG_FORMAT_FLAG_LINEAR;
1387
1388 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1389 format |= PNG_FORMAT_FLAG_COLORMAP;
1390
1391 return format;
1392 }
1393
1394 /* Is the given gamma significantly different from sRGB? The test is the same
1395 * one used in pngrtran.c when deciding whether to do gamma correction. The
1396 * arithmetic optimizes the division by using the fact that the inverse of the
1397 * file sRGB gamma is 2.2
1398 */
1399 static int
1400 png_gamma_not_sRGB(png_fixed_point g)
1401 {
1402 if (g < PNG_FP_1)
1403 {
1404 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1405 if (g == 0)
1406 return 0;
1407
1408 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1409 }
1410
1411 return 1;
1412 }
1413
1414 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1415 * header and fill in all the information. This is executed in a safe context,
1416 * unlike the init routine above.
1417 */
1418 static int
1419 png_image_read_header(png_voidp argument)
1420 {
1421 png_imagep image = png_voidcast(png_imagep, argument);
1422 png_structrp png_ptr = image->opaque->png_ptr;
1423 png_inforp info_ptr = image->opaque->info_ptr;
1424
1425 png_set_benign_errors(png_ptr, 1/*warn*/);
1426 png_read_info(png_ptr, info_ptr);
1427
1428 /* Do this the fast way; just read directly out of png_struct. */
1429 image->width = png_ptr->width;
1430 image->height = png_ptr->height;
1431
1432 {
1433 png_uint_32 format = png_image_format(png_ptr);
1434
1435 image->format = format;
1436
1437 #ifdef PNG_COLORSPACE_SUPPORTED
1438 /* Does the colorspace match sRGB? If there is no color endpoint
1439 * (colorant) information assume yes, otherwise require the
1440 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1441 * colorspace has been determined to be invalid ignore it.
1442 */
1443 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1444 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1445 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1446 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1447 #endif
1448 }
1449
1450 /* We need the maximum number of entries regardless of the format the
1451 * application sets here.
1452 */
1453 {
1454 png_uint_32 cmap_entries;
1455
1456 switch (png_ptr->color_type)
1457 {
1458 case PNG_COLOR_TYPE_GRAY:
1459 cmap_entries = 1U << png_ptr->bit_depth;
1460 break;
1461
1462 case PNG_COLOR_TYPE_PALETTE:
1463 cmap_entries = png_ptr->num_palette;
1464 break;
1465
1466 default:
1467 cmap_entries = 256;
1468 break;
1469 }
1470
1471 if (cmap_entries > 256)
1472 cmap_entries = 256;
1473
1474 image->colormap_entries = cmap_entries;
1475 }
1476
1477 return 1;
1478 }
1479
1480 #ifdef PNG_STDIO_SUPPORTED
1481 int PNGAPI
1482 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1483 {
1484 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1485 {
1486 if (file != NULL)
1487 {
1488 if (png_image_read_init(image) != 0)
1489 {
1490 /* This is slightly evil, but png_init_io doesn't do anything other
1491 * than this and we haven't changed the standard IO functions so
1492 * this saves a 'safe' function.
1493 */
1494 image->opaque->png_ptr->io_ptr = file;
1495 return png_safe_execute(image, png_image_read_header, image);
1496 }
1497 }
1498
1499 else
1500 return png_image_error(image,
1501 "png_image_begin_read_from_stdio: invalid argument");
1502 }
1503
1504 else if (image != NULL)
1505 return png_image_error(image,
1506 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1507
1508 return 0;
1509 }
1510
1511 int PNGAPI
1512 png_image_begin_read_from_file(png_imagep image, const char *file_name)
1513 {
1514 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1515 {
1516 if (file_name != NULL)
1517 {
1518 FILE *fp = fopen(file_name, "rb");
1519
1520 if (fp != NULL)
1521 {
1522 if (png_image_read_init(image) != 0)
1523 {
1524 image->opaque->png_ptr->io_ptr = fp;
1525 image->opaque->owned_file = 1;
1526 return png_safe_execute(image, png_image_read_header, image);
1527 }
1528
1529 /* Clean up: just the opened file. */
1530 (void)fclose(fp);
1531 }
1532
1533 else
1534 return png_image_error(image, strerror(errno));
1535 }
1536
1537 else
1538 return png_image_error(image,
1539 "png_image_begin_read_from_file: invalid argument");
1540 }
1541
1542 else if (image != NULL)
1543 return png_image_error(image,
1544 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1545
1546 return 0;
1547 }
1548 #endif /* STDIO */
1549
1550 static void PNGCBAPI
1551 png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
1552 {
1553 if (png_ptr != NULL)
1554 {
1555 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1556 if (image != NULL)
1557 {
1558 png_controlp cp = image->opaque;
1559 if (cp != NULL)
1560 {
1561 png_const_bytep memory = cp->memory;
1562 png_size_t size = cp->size;
1563
1564 if (memory != NULL && size >= need)
1565 {
1566 memcpy(out, memory, need);
1567 cp->memory = memory + need;
1568 cp->size = size - need;
1569 return;
1570 }
1571
1572 png_error(png_ptr, "read beyond end of data");
1573 }
1574 }
1575
1576 png_error(png_ptr, "invalid memory read");
1577 }
1578 }
1579
1580 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1581 png_const_voidp memory, png_size_t size)
1582 {
1583 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1584 {
1585 if (memory != NULL && size > 0)
1586 {
1587 if (png_image_read_init(image) != 0)
1588 {
1589 /* Now set the IO functions to read from the memory buffer and
1590 * store it into io_ptr. Again do this in-place to avoid calling a
1591 * libpng function that requires error handling.
1592 */
1593 image->opaque->memory = png_voidcast(png_const_bytep, memory);
1594 image->opaque->size = size;
1595 image->opaque->png_ptr->io_ptr = image;
1596 image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1597
1598 return png_safe_execute(image, png_image_read_header, image);
1599 }
1600 }
1601
1602 else
1603 return png_image_error(image,
1604 "png_image_begin_read_from_memory: invalid argument");
1605 }
1606
1607 else if (image != NULL)
1608 return png_image_error(image,
1609 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1610
1611 return 0;
1612 }
1613
1614 /* Utility function to skip chunks that are not used by the simplified image
1615 * read functions and an appropriate macro to call it.
1616 */
1617 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1618 static void
1619 png_image_skip_unused_chunks(png_structrp png_ptr)
1620 {
1621 /* Prepare the reader to ignore all recognized chunks whose data will not
1622 * be used, i.e., all chunks recognized by libpng except for those
1623 * involved in basic image reading:
1624 *
1625 * IHDR, PLTE, IDAT, IEND
1626 *
1627 * Or image data handling:
1628 *
1629 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1630 *
1631 * This provides a small performance improvement and eliminates any
1632 * potential vulnerability to security problems in the unused chunks.
1633 *
1634 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1635 * too. This allows the simplified API to be compiled without iCCP support,
1636 * however if the support is there the chunk is still checked to detect
1637 * errors (which are unfortunately quite common.)
1638 */
1639 {
1640 static PNG_CONST png_byte chunks_to_process[] = {
1641 98, 75, 71, 68, '\0', /* bKGD */
1642 99, 72, 82, 77, '\0', /* cHRM */
1643 103, 65, 77, 65, '\0', /* gAMA */
1644 # ifdef PNG_READ_iCCP_SUPPORTED
1645 105, 67, 67, 80, '\0', /* iCCP */
1646 # endif
1647 115, 66, 73, 84, '\0', /* sBIT */
1648 115, 82, 71, 66, '\0', /* sRGB */
1649 };
1650
1651 /* Ignore unknown chunks and all other chunks except for the
1652 * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1653 */
1654 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1655 NULL, -1);
1656
1657 /* But do not ignore image data handling chunks */
1658 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1659 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1660 }
1661 }
1662
1663 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1664 #else
1665 # define PNG_SKIP_CHUNKS(p) ((void)0)
1666 #endif /* HANDLE_AS_UNKNOWN */
1667
1668 /* The following macro gives the exact rounded answer for all values in the
1669 * range 0..255 (it actually divides by 51.2, but the rounding still generates
1670 * the correct numbers 0..5
1671 */
1672 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1673
1674 /* Utility functions to make particular color-maps */
1675 static void
1676 set_file_encoding(png_image_read_control *display)
1677 {
1678 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1679 if (png_gamma_significant(g) != 0)
1680 {
1681 if (png_gamma_not_sRGB(g) != 0)
1682 {
1683 display->file_encoding = P_FILE;
1684 display->gamma_to_linear = png_reciprocal(g);
1685 }
1686
1687 else
1688 display->file_encoding = P_sRGB;
1689 }
1690
1691 else
1692 display->file_encoding = P_LINEAR8;
1693 }
1694
1695 static unsigned int
1696 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1697 {
1698 if (encoding == P_FILE) /* double check */
1699 encoding = display->file_encoding;
1700
1701 if (encoding == P_NOTSET) /* must be the file encoding */
1702 {
1703 set_file_encoding(display);
1704 encoding = display->file_encoding;
1705 }
1706
1707 switch (encoding)
1708 {
1709 case P_FILE:
1710 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1711 break;
1712
1713 case P_sRGB:
1714 value = png_sRGB_table[value];
1715 break;
1716
1717 case P_LINEAR:
1718 break;
1719
1720 case P_LINEAR8:
1721 value *= 257;
1722 break;
1723
1724 #ifdef __GNUC__
1725 default:
1726 png_error(display->image->opaque->png_ptr,
1727 "unexpected encoding (internal error)");
1728 #endif
1729 }
1730
1731 return value;
1732 }
1733
1734 static png_uint_32
1735 png_colormap_compose(png_image_read_control *display,
1736 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1737 png_uint_32 background, int encoding)
1738 {
1739 /* The file value is composed on the background, the background has the given
1740 * encoding and so does the result, the file is encoded with P_FILE and the
1741 * file and alpha are 8-bit values. The (output) encoding will always be
1742 * P_LINEAR or P_sRGB.
1743 */
1744 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1745 png_uint_32 b = decode_gamma(display, background, encoding);
1746
1747 /* The alpha is always an 8-bit value (it comes from the palette), the value
1748 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1749 */
1750 f = f * alpha + b * (255-alpha);
1751
1752 if (encoding == P_LINEAR)
1753 {
1754 /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1755 * accurate, it divides by 255.00000005937181414556, with no overflow.)
1756 */
1757 f *= 257; /* Now scaled by 65535 */
1758 f += f >> 16;
1759 f = (f+32768) >> 16;
1760 }
1761
1762 else /* P_sRGB */
1763 f = PNG_sRGB_FROM_LINEAR(f);
1764
1765 return f;
1766 }
1767
1768 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1769 * be 8-bit.
1770 */
1771 static void
1772 png_create_colormap_entry(png_image_read_control *display,
1773 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1774 png_uint_32 alpha, int encoding)
1775 {
1776 png_imagep image = display->image;
1777 const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1778 P_LINEAR : P_sRGB;
1779 const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1780 (red != green || green != blue);
1781
1782 if (ip > 255)
1783 png_error(image->opaque->png_ptr, "color-map index out of range");
1784
1785 /* Update the cache with whether the file gamma is significantly different
1786 * from sRGB.
1787 */
1788 if (encoding == P_FILE)
1789 {
1790 if (display->file_encoding == P_NOTSET)
1791 set_file_encoding(display);
1792
1793 /* Note that the cached value may be P_FILE too, but if it is then the
1794 * gamma_to_linear member has been set.
1795 */
1796 encoding = display->file_encoding;
1797 }
1798
1799 if (encoding == P_FILE)
1800 {
1801 png_fixed_point g = display->gamma_to_linear;
1802
1803 red = png_gamma_16bit_correct(red*257, g);
1804 green = png_gamma_16bit_correct(green*257, g);
1805 blue = png_gamma_16bit_correct(blue*257, g);
1806
1807 if (convert_to_Y != 0 || output_encoding == P_LINEAR)
1808 {
1809 alpha *= 257;
1810 encoding = P_LINEAR;
1811 }
1812
1813 else
1814 {
1815 red = PNG_sRGB_FROM_LINEAR(red * 255);
1816 green = PNG_sRGB_FROM_LINEAR(green * 255);
1817 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1818 encoding = P_sRGB;
1819 }
1820 }
1821
1822 else if (encoding == P_LINEAR8)
1823 {
1824 /* This encoding occurs quite frequently in test cases because PngSuite
1825 * includes a gAMA 1.0 chunk with most images.
1826 */
1827 red *= 257;
1828 green *= 257;
1829 blue *= 257;
1830 alpha *= 257;
1831 encoding = P_LINEAR;
1832 }
1833
1834 else if (encoding == P_sRGB &&
1835 (convert_to_Y != 0 || output_encoding == P_LINEAR))
1836 {
1837 /* The values are 8-bit sRGB values, but must be converted to 16-bit
1838 * linear.
1839 */
1840 red = png_sRGB_table[red];
1841 green = png_sRGB_table[green];
1842 blue = png_sRGB_table[blue];
1843 alpha *= 257;
1844 encoding = P_LINEAR;
1845 }
1846
1847 /* This is set if the color isn't gray but the output is. */
1848 if (encoding == P_LINEAR)
1849 {
1850 if (convert_to_Y != 0)
1851 {
1852 /* NOTE: these values are copied from png_do_rgb_to_gray */
1853 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
1854 (png_uint_32)2366 * blue;
1855
1856 if (output_encoding == P_LINEAR)
1857 y = (y + 16384) >> 15;
1858
1859 else
1860 {
1861 /* y is scaled by 32768, we need it scaled by 255: */
1862 y = (y + 128) >> 8;
1863 y *= 255;
1864 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
1865 alpha = PNG_DIV257(alpha);
1866 encoding = P_sRGB;
1867 }
1868
1869 blue = red = green = y;
1870 }
1871
1872 else if (output_encoding == P_sRGB)
1873 {
1874 red = PNG_sRGB_FROM_LINEAR(red * 255);
1875 green = PNG_sRGB_FROM_LINEAR(green * 255);
1876 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1877 alpha = PNG_DIV257(alpha);
1878 encoding = P_sRGB;
1879 }
1880 }
1881
1882 if (encoding != output_encoding)
1883 png_error(image->opaque->png_ptr, "bad encoding (internal error)");
1884
1885 /* Store the value. */
1886 {
1887 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1888 const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1889 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
1890 # else
1891 # define afirst 0
1892 # endif
1893 # ifdef PNG_FORMAT_BGR_SUPPORTED
1894 const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1895 # else
1896 # define bgr 0
1897 # endif
1898
1899 if (output_encoding == P_LINEAR)
1900 {
1901 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
1902
1903 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1904
1905 /* The linear 16-bit values must be pre-multiplied by the alpha channel
1906 * value, if less than 65535 (this is, effectively, composite on black
1907 * if the alpha channel is removed.)
1908 */
1909 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1910 {
1911 case 4:
1912 entry[afirst ? 0 : 3] = (png_uint_16)alpha;
1913 /* FALL THROUGH */
1914
1915 case 3:
1916 if (alpha < 65535)
1917 {
1918 if (alpha > 0)
1919 {
1920 blue = (blue * alpha + 32767U)/65535U;
1921 green = (green * alpha + 32767U)/65535U;
1922 red = (red * alpha + 32767U)/65535U;
1923 }
1924
1925 else
1926 red = green = blue = 0;
1927 }
1928 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
1929 entry[afirst + 1] = (png_uint_16)green;
1930 entry[afirst + bgr] = (png_uint_16)red;
1931 break;
1932
1933 case 2:
1934 entry[1 ^ afirst] = (png_uint_16)alpha;
1935 /* FALL THROUGH */
1936
1937 case 1:
1938 if (alpha < 65535)
1939 {
1940 if (alpha > 0)
1941 green = (green * alpha + 32767U)/65535U;
1942
1943 else
1944 green = 0;
1945 }
1946 entry[afirst] = (png_uint_16)green;
1947 break;
1948
1949 default:
1950 break;
1951 }
1952 }
1953
1954 else /* output encoding is P_sRGB */
1955 {
1956 png_bytep entry = png_voidcast(png_bytep, display->colormap);
1957
1958 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1959
1960 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1961 {
1962 case 4:
1963 entry[afirst ? 0 : 3] = (png_byte)alpha;
1964 case 3:
1965 entry[afirst + (2 ^ bgr)] = (png_byte)blue;
1966 entry[afirst + 1] = (png_byte)green;
1967 entry[afirst + bgr] = (png_byte)red;
1968 break;
1969
1970 case 2:
1971 entry[1 ^ afirst] = (png_byte)alpha;
1972 case 1:
1973 entry[afirst] = (png_byte)green;
1974 break;
1975
1976 default:
1977 break;
1978 }
1979 }
1980
1981 # ifdef afirst
1982 # undef afirst
1983 # endif
1984 # ifdef bgr
1985 # undef bgr
1986 # endif
1987 }
1988 }
1989
1990 static int
1991 make_gray_file_colormap(png_image_read_control *display)
1992 {
1993 unsigned int i;
1994
1995 for (i=0; i<256; ++i)
1996 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
1997
1998 return i;
1999 }
2000
2001 static int
2002 make_gray_colormap(png_image_read_control *display)
2003 {
2004 unsigned int i;
2005
2006 for (i=0; i<256; ++i)
2007 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2008
2009 return i;
2010 }
2011 #define PNG_GRAY_COLORMAP_ENTRIES 256
2012
2013 static int
2014 make_ga_colormap(png_image_read_control *display)
2015 {
2016 unsigned int i, a;
2017
2018 /* Alpha is retained, the output will be a color-map with entries
2019 * selected by six levels of alpha. One transparent entry, 6 gray
2020 * levels for all the intermediate alpha values, leaving 230 entries
2021 * for the opaque grays. The color-map entries are the six values
2022 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2023 * relevant entry.
2024 *
2025 * if (alpha > 229) // opaque
2026 * {
2027 * // The 231 entries are selected to make the math below work:
2028 * base = 0;
2029 * entry = (231 * gray + 128) >> 8;
2030 * }
2031 * else if (alpha < 26) // transparent
2032 * {
2033 * base = 231;
2034 * entry = 0;
2035 * }
2036 * else // partially opaque
2037 * {
2038 * base = 226 + 6 * PNG_DIV51(alpha);
2039 * entry = PNG_DIV51(gray);
2040 * }
2041 */
2042 i = 0;
2043 while (i < 231)
2044 {
2045 unsigned int gray = (i * 256 + 115) / 231;
2046 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2047 }
2048
2049 /* 255 is used here for the component values for consistency with the code
2050 * that undoes premultiplication in pngwrite.c.
2051 */
2052 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2053
2054 for (a=1; a<5; ++a)
2055 {
2056 unsigned int g;
2057
2058 for (g=0; g<6; ++g)
2059 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2060 P_sRGB);
2061 }
2062
2063 return i;
2064 }
2065
2066 #define PNG_GA_COLORMAP_ENTRIES 256
2067
2068 static int
2069 make_rgb_colormap(png_image_read_control *display)
2070 {
2071 unsigned int i, r;
2072
2073 /* Build a 6x6x6 opaque RGB cube */
2074 for (i=r=0; r<6; ++r)
2075 {
2076 unsigned int g;
2077
2078 for (g=0; g<6; ++g)
2079 {
2080 unsigned int b;
2081
2082 for (b=0; b<6; ++b)
2083 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2084 P_sRGB);
2085 }
2086 }
2087
2088 return i;
2089 }
2090
2091 #define PNG_RGB_COLORMAP_ENTRIES 216
2092
2093 /* Return a palette index to the above palette given three 8-bit sRGB values. */
2094 #define PNG_RGB_INDEX(r,g,b) \
2095 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2096
2097 static int
2098 png_image_read_colormap(png_voidp argument)
2099 {
2100 png_image_read_control *display =
2101 png_voidcast(png_image_read_control*, argument);
2102 const png_imagep image = display->image;
2103
2104 const png_structrp png_ptr = image->opaque->png_ptr;
2105 const png_uint_32 output_format = image->format;
2106 const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2107 P_LINEAR : P_sRGB;
2108
2109 unsigned int cmap_entries;
2110 unsigned int output_processing; /* Output processing option */
2111 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2112
2113 /* Background information; the background color and the index of this color
2114 * in the color-map if it exists (else 256).
2115 */
2116 unsigned int background_index = 256;
2117 png_uint_32 back_r, back_g, back_b;
2118
2119 /* Flags to accumulate things that need to be done to the input. */
2120 int expand_tRNS = 0;
2121
2122 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2123 * very difficult to do, the results look awful, and it is difficult to see
2124 * what possible use it is because the application can't control the
2125 * color-map.
2126 */
2127 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2128 png_ptr->num_trans > 0) /* alpha in input */ &&
2129 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2130 {
2131 if (output_encoding == P_LINEAR) /* compose on black */
2132 back_b = back_g = back_r = 0;
2133
2134 else if (display->background == NULL /* no way to remove it */)
2135 png_error(png_ptr,
2136 "a background color must be supplied to remove alpha/transparency");
2137
2138 /* Get a copy of the background color (this avoids repeating the checks
2139 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2140 * output format.
2141 */
2142 else
2143 {
2144 back_g = display->background->green;
2145 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2146 {
2147 back_r = display->background->red;
2148 back_b = display->background->blue;
2149 }
2150 else
2151 back_b = back_r = back_g;
2152 }
2153 }
2154
2155 else if (output_encoding == P_LINEAR)
2156 back_b = back_r = back_g = 65535;
2157
2158 else
2159 back_b = back_r = back_g = 255;
2160
2161 /* Default the input file gamma if required - this is necessary because
2162 * libpng assumes that if no gamma information is present the data is in the
2163 * output format, but the simplified API deduces the gamma from the input
2164 * format.
2165 */
2166 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2167 {
2168 /* Do this directly, not using the png_colorspace functions, to ensure
2169 * that it happens even if the colorspace is invalid (though probably if
2170 * it is the setting will be ignored) Note that the same thing can be
2171 * achieved at the application interface with png_set_gAMA.
2172 */
2173 if (png_ptr->bit_depth == 16 &&
2174 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2175 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2176
2177 else
2178 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2179
2180 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2181 }
2182
2183 /* Decide what to do based on the PNG color type of the input data. The
2184 * utility function png_create_colormap_entry deals with most aspects of the
2185 * output transformations; this code works out how to produce bytes of
2186 * color-map entries from the original format.
2187 */
2188 switch (png_ptr->color_type)
2189 {
2190 case PNG_COLOR_TYPE_GRAY:
2191 if (png_ptr->bit_depth <= 8)
2192 {
2193 /* There at most 256 colors in the output, regardless of
2194 * transparency.
2195 */
2196 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2197
2198 cmap_entries = 1U << png_ptr->bit_depth;
2199 if (cmap_entries > image->colormap_entries)
2200 png_error(png_ptr, "gray[8] color-map: too few entries");
2201
2202 step = 255 / (cmap_entries - 1);
2203 output_processing = PNG_CMAP_NONE;
2204
2205 /* If there is a tRNS chunk then this either selects a transparent
2206 * value or, if the output has no alpha, the background color.
2207 */
2208 if (png_ptr->num_trans > 0)
2209 {
2210 trans = png_ptr->trans_color.gray;
2211
2212 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2213 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2214 }
2215
2216 /* png_create_colormap_entry just takes an RGBA and writes the
2217 * corresponding color-map entry using the format from 'image',
2218 * including the required conversion to sRGB or linear as
2219 * appropriate. The input values are always either sRGB (if the
2220 * gamma correction flag is 0) or 0..255 scaled file encoded values
2221 * (if the function must gamma correct them).
2222 */
2223 for (i=val=0; i<cmap_entries; ++i, val += step)
2224 {
2225 /* 'i' is a file value. While this will result in duplicated
2226 * entries for 8-bit non-sRGB encoded files it is necessary to
2227 * have non-gamma corrected values to do tRNS handling.
2228 */
2229 if (i != trans)
2230 png_create_colormap_entry(display, i, val, val, val, 255,
2231 P_FILE/*8-bit with file gamma*/);
2232
2233 /* Else this entry is transparent. The colors don't matter if
2234 * there is an alpha channel (back_alpha == 0), but it does no
2235 * harm to pass them in; the values are not set above so this
2236 * passes in white.
2237 *
2238 * NOTE: this preserves the full precision of the application
2239 * supplied background color when it is used.
2240 */
2241 else
2242 png_create_colormap_entry(display, i, back_r, back_g, back_b,
2243 back_alpha, output_encoding);
2244 }
2245
2246 /* We need libpng to preserve the original encoding. */
2247 data_encoding = P_FILE;
2248
2249 /* The rows from libpng, while technically gray values, are now also
2250 * color-map indices; however, they may need to be expanded to 1
2251 * byte per pixel. This is what png_set_packing does (i.e., it
2252 * unpacks the bit values into bytes.)
2253 */
2254 if (png_ptr->bit_depth < 8)
2255 png_set_packing(png_ptr);
2256 }
2257
2258 else /* bit depth is 16 */
2259 {
2260 /* The 16-bit input values can be converted directly to 8-bit gamma
2261 * encoded values; however, if a tRNS chunk is present 257 color-map
2262 * entries are required. This means that the extra entry requires
2263 * special processing; add an alpha channel, sacrifice gray level
2264 * 254 and convert transparent (alpha==0) entries to that.
2265 *
2266 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2267 * same time to minimize quality loss. If a tRNS chunk is present
2268 * this means libpng must handle it too; otherwise it is impossible
2269 * to do the exact match on the 16-bit value.
2270 *
2271 * If the output has no alpha channel *and* the background color is
2272 * gray then it is possible to let libpng handle the substitution by
2273 * ensuring that the corresponding gray level matches the background
2274 * color exactly.
2275 */
2276 data_encoding = P_sRGB;
2277
2278 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2279 png_error(png_ptr, "gray[16] color-map: too few entries");
2280
2281 cmap_entries = make_gray_colormap(display);
2282
2283 if (png_ptr->num_trans > 0)
2284 {
2285 unsigned int back_alpha;
2286
2287 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2288 back_alpha = 0;
2289
2290 else
2291 {
2292 if (back_r == back_g && back_g == back_b)
2293 {
2294 /* Background is gray; no special processing will be
2295 * required.
2296 */
2297 png_color_16 c;
2298 png_uint_32 gray = back_g;
2299
2300 if (output_encoding == P_LINEAR)
2301 {
2302 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2303
2304 /* And make sure the corresponding palette entry
2305 * matches.
2306 */
2307 png_create_colormap_entry(display, gray, back_g, back_g,
2308 back_g, 65535, P_LINEAR);
2309 }
2310
2311 /* The background passed to libpng, however, must be the
2312 * sRGB value.
2313 */
2314 c.index = 0; /*unused*/
2315 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2316
2317 /* NOTE: does this work without expanding tRNS to alpha?
2318 * It should be the color->gray case below apparently
2319 * doesn't.
2320 */
2321 png_set_background_fixed(png_ptr, &c,
2322 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2323 0/*gamma: not used*/);
2324
2325 output_processing = PNG_CMAP_NONE;
2326 break;
2327 }
2328 #ifdef __COVERITY__
2329 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2330 * here.
2331 */
2332 back_alpha = 255;
2333 #else
2334 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2335 #endif
2336 }
2337
2338 /* output_processing means that the libpng-processed row will be
2339 * 8-bit GA and it has to be processing to single byte color-map
2340 * values. Entry 254 is replaced by either a completely
2341 * transparent entry or by the background color at full
2342 * precision (and the background color is not a simple gray
2343 * level in this case.)
2344 */
2345 expand_tRNS = 1;
2346 output_processing = PNG_CMAP_TRANS;
2347 background_index = 254;
2348
2349 /* And set (overwrite) color-map entry 254 to the actual
2350 * background color at full precision.
2351 */
2352 png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2353 back_alpha, output_encoding);
2354 }
2355
2356 else
2357 output_processing = PNG_CMAP_NONE;
2358 }
2359 break;
2360
2361 case PNG_COLOR_TYPE_GRAY_ALPHA:
2362 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2363 * of 65536 combinations. If, however, the alpha channel is to be
2364 * removed there are only 256 possibilities if the background is gray.
2365 * (Otherwise there is a subset of the 65536 possibilities defined by
2366 * the triangle between black, white and the background color.)
2367 *
2368 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2369 * worry about tRNS matching - tRNS is ignored if there is an alpha
2370 * channel.
2371 */
2372 data_encoding = P_sRGB;
2373
2374 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2375 {
2376 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2377 png_error(png_ptr, "gray+alpha color-map: too few entries");
2378
2379 cmap_entries = make_ga_colormap(display);
2380
2381 background_index = PNG_CMAP_GA_BACKGROUND;
2382 output_processing = PNG_CMAP_GA;
2383 }
2384
2385 else /* alpha is removed */
2386 {
2387 /* Alpha must be removed as the PNG data is processed when the
2388 * background is a color because the G and A channels are
2389 * independent and the vector addition (non-parallel vectors) is a
2390 * 2-D problem.
2391 *
2392 * This can be reduced to the same algorithm as above by making a
2393 * colormap containing gray levels (for the opaque grays), a
2394 * background entry (for a transparent pixel) and a set of four six
2395 * level color values, one set for each intermediate alpha value.
2396 * See the comments in make_ga_colormap for how this works in the
2397 * per-pixel processing.
2398 *
2399 * If the background is gray, however, we only need a 256 entry gray
2400 * level color map. It is sufficient to make the entry generated
2401 * for the background color be exactly the color specified.
2402 */
2403 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2404 (back_r == back_g && back_g == back_b))
2405 {
2406 /* Background is gray; no special processing will be required. */
2407 png_color_16 c;
2408 png_uint_32 gray = back_g;
2409
2410 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2411 png_error(png_ptr, "gray-alpha color-map: too few entries");
2412
2413 cmap_entries = make_gray_colormap(display);
2414
2415 if (output_encoding == P_LINEAR)
2416 {
2417 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2418
2419 /* And make sure the corresponding palette entry matches. */
2420 png_create_colormap_entry(display, gray, back_g, back_g,
2421 back_g, 65535, P_LINEAR);
2422 }
2423
2424 /* The background passed to libpng, however, must be the sRGB
2425 * value.
2426 */
2427 c.index = 0; /*unused*/
2428 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2429
2430 png_set_background_fixed(png_ptr, &c,
2431 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2432 0/*gamma: not used*/);
2433
2434 output_processing = PNG_CMAP_NONE;
2435 }
2436
2437 else
2438 {
2439 png_uint_32 i, a;
2440
2441 /* This is the same as png_make_ga_colormap, above, except that
2442 * the entries are all opaque.
2443 */
2444 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2445 png_error(png_ptr, "ga-alpha color-map: too few entries");
2446
2447 i = 0;
2448 while (i < 231)
2449 {
2450 png_uint_32 gray = (i * 256 + 115) / 231;
2451 png_create_colormap_entry(display, i++, gray, gray, gray,
2452 255, P_sRGB);
2453 }
2454
2455 /* NOTE: this preserves the full precision of the application
2456 * background color.
2457 */
2458 background_index = i;
2459 png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2460 #ifdef __COVERITY__
2461 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2462 * here.
2463 */ 255U,
2464 #else
2465 output_encoding == P_LINEAR ? 65535U : 255U,
2466 #endif
2467 output_encoding);
2468
2469 /* For non-opaque input composite on the sRGB background - this
2470 * requires inverting the encoding for each component. The input
2471 * is still converted to the sRGB encoding because this is a
2472 * reasonable approximate to the logarithmic curve of human
2473 * visual sensitivity, at least over the narrow range which PNG
2474 * represents. Consequently 'G' is always sRGB encoded, while
2475 * 'A' is linear. We need the linear background colors.
2476 */
2477 if (output_encoding == P_sRGB) /* else already linear */
2478 {
2479 /* This may produce a value not exactly matching the
2480 * background, but that's ok because these numbers are only
2481 * used when alpha != 0
2482 */
2483 back_r = png_sRGB_table[back_r];
2484 back_g = png_sRGB_table[back_g];
2485 back_b = png_sRGB_table[back_b];
2486 }
2487
2488 for (a=1; a<5; ++a)
2489 {
2490 unsigned int g;
2491
2492 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2493 * by an 8-bit alpha value (0..255).
2494 */
2495 png_uint_32 alpha = 51 * a;
2496 png_uint_32 back_rx = (255-alpha) * back_r;
2497 png_uint_32 back_gx = (255-alpha) * back_g;
2498 png_uint_32 back_bx = (255-alpha) * back_b;
2499
2500 for (g=0; g<6; ++g)
2501 {
2502 png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2503
2504 png_create_colormap_entry(display, i++,
2505 PNG_sRGB_FROM_LINEAR(gray + back_rx),
2506 PNG_sRGB_FROM_LINEAR(gray + back_gx),
2507 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2508 }
2509 }
2510
2511 cmap_entries = i;
2512 output_processing = PNG_CMAP_GA;
2513 }
2514 }
2515 break;
2516
2517 case PNG_COLOR_TYPE_RGB:
2518 case PNG_COLOR_TYPE_RGB_ALPHA:
2519 /* Exclude the case where the output is gray; we can always handle this
2520 * with the cases above.
2521 */
2522 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2523 {
2524 /* The color-map will be grayscale, so we may as well convert the
2525 * input RGB values to a simple grayscale and use the grayscale
2526 * code above.
2527 *
2528 * NOTE: calling this apparently damages the recognition of the
2529 * transparent color in background color handling; call
2530 * png_set_tRNS_to_alpha before png_set_background_fixed.
2531 */
2532 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2533 -1);
2534 data_encoding = P_sRGB;
2535
2536 /* The output will now be one or two 8-bit gray or gray+alpha
2537 * channels. The more complex case arises when the input has alpha.
2538 */
2539 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2540 png_ptr->num_trans > 0) &&
2541 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2542 {
2543 /* Both input and output have an alpha channel, so no background
2544 * processing is required; just map the GA bytes to the right
2545 * color-map entry.
2546 */
2547 expand_tRNS = 1;
2548
2549 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2550 png_error(png_ptr, "rgb[ga] color-map: too few entries");
2551
2552 cmap_entries = make_ga_colormap(display);
2553 background_index = PNG_CMAP_GA_BACKGROUND;
2554 output_processing = PNG_CMAP_GA;
2555 }
2556
2557 else
2558 {
2559 /* Either the input or the output has no alpha channel, so there
2560 * will be no non-opaque pixels in the color-map; it will just be
2561 * grayscale.
2562 */
2563 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2564 png_error(png_ptr, "rgb[gray] color-map: too few entries");
2565
2566 /* Ideally this code would use libpng to do the gamma correction,
2567 * but if an input alpha channel is to be removed we will hit the
2568 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2569 * correction bug). Fix this by dropping the gamma correction in
2570 * this case and doing it in the palette; this will result in
2571 * duplicate palette entries, but that's better than the
2572 * alternative of double gamma correction.
2573 */
2574 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2575 png_ptr->num_trans > 0) &&
2576 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2577 {
2578 cmap_entries = make_gray_file_colormap(display);
2579 data_encoding = P_FILE;
2580 }
2581
2582 else
2583 cmap_entries = make_gray_colormap(display);
2584
2585 /* But if the input has alpha or transparency it must be removed
2586 */
2587 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2588 png_ptr->num_trans > 0)
2589 {
2590 png_color_16 c;
2591 png_uint_32 gray = back_g;
2592
2593 /* We need to ensure that the application background exists in
2594 * the colormap and that completely transparent pixels map to
2595 * it. Achieve this simply by ensuring that the entry
2596 * selected for the background really is the background color.
2597 */
2598 if (data_encoding == P_FILE) /* from the fixup above */
2599 {
2600 /* The app supplied a gray which is in output_encoding, we
2601 * need to convert it to a value of the input (P_FILE)
2602 * encoding then set this palette entry to the required
2603 * output encoding.
2604 */
2605 if (output_encoding == P_sRGB)
2606 gray = png_sRGB_table[gray]; /* now P_LINEAR */
2607
2608 gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2609 png_ptr->colorspace.gamma)); /* now P_FILE */
2610
2611 /* And make sure the corresponding palette entry contains
2612 * exactly the required sRGB value.
2613 */
2614 png_create_colormap_entry(display, gray, back_g, back_g,
2615 back_g, 0/*unused*/, output_encoding);
2616 }
2617
2618 else if (output_encoding == P_LINEAR)
2619 {
2620 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2621
2622 /* And make sure the corresponding palette entry matches.
2623 */
2624 png_create_colormap_entry(display, gray, back_g, back_g,
2625 back_g, 0/*unused*/, P_LINEAR);
2626 }
2627
2628 /* The background passed to libpng, however, must be the
2629 * output (normally sRGB) value.
2630 */
2631 c.index = 0; /*unused*/
2632 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2633
2634 /* NOTE: the following is apparently a bug in libpng. Without
2635 * it the transparent color recognition in
2636 * png_set_background_fixed seems to go wrong.
2637 */
2638 expand_tRNS = 1;
2639 png_set_background_fixed(png_ptr, &c,
2640 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2641 0/*gamma: not used*/);
2642 }
2643
2644 output_processing = PNG_CMAP_NONE;
2645 }
2646 }
2647
2648 else /* output is color */
2649 {
2650 /* We could use png_quantize here so long as there is no transparent
2651 * color or alpha; png_quantize ignores alpha. Easier overall just
2652 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2653 * Consequently we always want libpng to produce sRGB data.
2654 */
2655 data_encoding = P_sRGB;
2656
2657 /* Is there any transparency or alpha? */
2658 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2659 png_ptr->num_trans > 0)
2660 {
2661 /* Is there alpha in the output too? If so all four channels are
2662 * processed into a special RGB cube with alpha support.
2663 */
2664 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2665 {
2666 png_uint_32 r;
2667
2668 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2669 png_error(png_ptr, "rgb+alpha color-map: too few entries");
2670
2671 cmap_entries = make_rgb_colormap(display);
2672
2673 /* Add a transparent entry. */
2674 png_create_colormap_entry(display, cmap_entries, 255, 255,
2675 255, 0, P_sRGB);
2676
2677 /* This is stored as the background index for the processing
2678 * algorithm.
2679 */
2680 background_index = cmap_entries++;
2681
2682 /* Add 27 r,g,b entries each with alpha 0.5. */
2683 for (r=0; r<256; r = (r << 1) | 0x7f)
2684 {
2685 png_uint_32 g;
2686
2687 for (g=0; g<256; g = (g << 1) | 0x7f)
2688 {
2689 png_uint_32 b;
2690
2691 /* This generates components with the values 0, 127 and
2692 * 255
2693 */
2694 for (b=0; b<256; b = (b << 1) | 0x7f)
2695 png_create_colormap_entry(display, cmap_entries++,
2696 r, g, b, 128, P_sRGB);
2697 }
2698 }
2699
2700 expand_tRNS = 1;
2701 output_processing = PNG_CMAP_RGB_ALPHA;
2702 }
2703
2704 else
2705 {
2706 /* Alpha/transparency must be removed. The background must
2707 * exist in the color map (achieved by setting adding it after
2708 * the 666 color-map). If the standard processing code will
2709 * pick up this entry automatically that's all that is
2710 * required; libpng can be called to do the background
2711 * processing.
2712 */
2713 unsigned int sample_size =
2714 PNG_IMAGE_SAMPLE_SIZE(output_format);
2715 png_uint_32 r, g, b; /* sRGB background */
2716
2717 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2718 png_error(png_ptr, "rgb-alpha color-map: too few entries");
2719
2720 cmap_entries = make_rgb_colormap(display);
2721
2722 png_create_colormap_entry(display, cmap_entries, back_r,
2723 back_g, back_b, 0/*unused*/, output_encoding);
2724
2725 if (output_encoding == P_LINEAR)
2726 {
2727 r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2728 g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2729 b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2730 }
2731
2732 else
2733 {
2734 r = back_r;
2735 g = back_g;
2736 b = back_g;
2737 }
2738
2739 /* Compare the newly-created color-map entry with the one the
2740 * PNG_CMAP_RGB algorithm will use. If the two entries don't
2741 * match, add the new one and set this as the background
2742 * index.
2743 */
2744 if (memcmp((png_const_bytep)display->colormap +
2745 sample_size * cmap_entries,
2746 (png_const_bytep)display->colormap +
2747 sample_size * PNG_RGB_INDEX(r,g,b),
2748 sample_size) != 0)
2749 {
2750 /* The background color must be added. */
2751 background_index = cmap_entries++;
2752
2753 /* Add 27 r,g,b entries each with created by composing with
2754 * the background at alpha 0.5.
2755 */
2756 for (r=0; r<256; r = (r << 1) | 0x7f)
2757 {
2758 for (g=0; g<256; g = (g << 1) | 0x7f)
2759 {
2760 /* This generates components with the values 0, 127
2761 * and 255
2762 */
2763 for (b=0; b<256; b = (b << 1) | 0x7f)
2764 png_create_colormap_entry(display, cmap_entries++,
2765 png_colormap_compose(display, r, P_sRGB, 128,
2766 back_r, output_encoding),
2767 png_colormap_compose(display, g, P_sRGB, 128,
2768 back_g, output_encoding),
2769 png_colormap_compose(display, b, P_sRGB, 128,
2770 back_b, output_encoding),
2771 0/*unused*/, output_encoding);
2772 }
2773 }
2774
2775 expand_tRNS = 1;
2776 output_processing = PNG_CMAP_RGB_ALPHA;
2777 }
2778
2779 else /* background color is in the standard color-map */
2780 {
2781 png_color_16 c;
2782
2783 c.index = 0; /*unused*/
2784 c.red = (png_uint_16)back_r;
2785 c.gray = c.green = (png_uint_16)back_g;
2786 c.blue = (png_uint_16)back_b;
2787
2788 png_set_background_fixed(png_ptr, &c,
2789 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2790 0/*gamma: not used*/);
2791
2792 output_processing = PNG_CMAP_RGB;
2793 }
2794 }
2795 }
2796
2797 else /* no alpha or transparency in the input */
2798 {
2799 /* Alpha in the output is irrelevant, simply map the opaque input
2800 * pixels to the 6x6x6 color-map.
2801 */
2802 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2803 png_error(png_ptr, "rgb color-map: too few entries");
2804
2805 cmap_entries = make_rgb_colormap(display);
2806 output_processing = PNG_CMAP_RGB;
2807 }
2808 }
2809 break;
2810
2811 case PNG_COLOR_TYPE_PALETTE:
2812 /* It's already got a color-map. It may be necessary to eliminate the
2813 * tRNS entries though.
2814 */
2815 {
2816 unsigned int num_trans = png_ptr->num_trans;
2817 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
2818 png_const_colorp colormap = png_ptr->palette;
2819 const int do_background = trans != NULL &&
2820 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
2821 unsigned int i;
2822
2823 /* Just in case: */
2824 if (trans == NULL)
2825 num_trans = 0;
2826
2827 output_processing = PNG_CMAP_NONE;
2828 data_encoding = P_FILE; /* Don't change from color-map indices */
2829 cmap_entries = png_ptr->num_palette;
2830 if (cmap_entries > 256)
2831 cmap_entries = 256;
2832
2833 if (cmap_entries > image->colormap_entries)
2834 png_error(png_ptr, "palette color-map: too few entries");
2835
2836 for (i=0; i < cmap_entries; ++i)
2837 {
2838 if (do_background != 0 && i < num_trans && trans[i] < 255)
2839 {
2840 if (trans[i] == 0)
2841 png_create_colormap_entry(display, i, back_r, back_g,
2842 back_b, 0, output_encoding);
2843
2844 else
2845 {
2846 /* Must compose the PNG file color in the color-map entry
2847 * on the sRGB color in 'back'.
2848 */
2849 png_create_colormap_entry(display, i,
2850 png_colormap_compose(display, colormap[i].red, P_FILE,
2851 trans[i], back_r, output_encoding),
2852 png_colormap_compose(display, colormap[i].green, P_FILE,
2853 trans[i], back_g, output_encoding),
2854 png_colormap_compose(display, colormap[i].blue, P_FILE,
2855 trans[i], back_b, output_encoding),
2856 output_encoding == P_LINEAR ? trans[i] * 257U :
2857 trans[i],
2858 output_encoding);
2859 }
2860 }
2861
2862 else
2863 png_create_colormap_entry(display, i, colormap[i].red,
2864 colormap[i].green, colormap[i].blue,
2865 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
2866 }
2867
2868 /* The PNG data may have indices packed in fewer than 8 bits, it
2869 * must be expanded if so.
2870 */
2871 if (png_ptr->bit_depth < 8)
2872 png_set_packing(png_ptr);
2873 }
2874 break;
2875
2876 default:
2877 png_error(png_ptr, "invalid PNG color type");
2878 /*NOT REACHED*/
2879 }
2880
2881 /* Now deal with the output processing */
2882 if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
2883 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
2884 png_set_tRNS_to_alpha(png_ptr);
2885
2886 switch (data_encoding)
2887 {
2888 case P_sRGB:
2889 /* Change to 8-bit sRGB */
2890 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
2891 /* FALL THROUGH */
2892
2893 case P_FILE:
2894 if (png_ptr->bit_depth > 8)
2895 png_set_scale_16(png_ptr);
2896 break;
2897
2898 #ifdef __GNUC__
2899 default:
2900 png_error(png_ptr, "bad data option (internal error)");
2901 #endif
2902 }
2903
2904 if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
2905 png_error(png_ptr, "color map overflow (BAD internal error)");
2906
2907 image->colormap_entries = cmap_entries;
2908
2909 /* Double check using the recorded background index */
2910 switch (output_processing)
2911 {
2912 case PNG_CMAP_NONE:
2913 if (background_index != PNG_CMAP_NONE_BACKGROUND)
2914 goto bad_background;
2915 break;
2916
2917 case PNG_CMAP_GA:
2918 if (background_index != PNG_CMAP_GA_BACKGROUND)
2919 goto bad_background;
2920 break;
2921
2922 case PNG_CMAP_TRANS:
2923 if (background_index >= cmap_entries ||
2924 background_index != PNG_CMAP_TRANS_BACKGROUND)
2925 goto bad_background;
2926 break;
2927
2928 case PNG_CMAP_RGB:
2929 if (background_index != PNG_CMAP_RGB_BACKGROUND)
2930 goto bad_background;
2931 break;
2932
2933 case PNG_CMAP_RGB_ALPHA:
2934 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
2935 goto bad_background;
2936 break;
2937
2938 default:
2939 png_error(png_ptr, "bad processing option (internal error)");
2940
2941 bad_background:
2942 png_error(png_ptr, "bad background index (internal error)");
2943 }
2944
2945 display->colormap_processing = output_processing;
2946
2947 return 1/*ok*/;
2948 }
2949
2950 /* The final part of the color-map read called from png_image_finish_read. */
2951 static int
2952 png_image_read_and_map(png_voidp argument)
2953 {
2954 png_image_read_control *display = png_voidcast(png_image_read_control*,
2955 argument);
2956 png_imagep image = display->image;
2957 png_structrp png_ptr = image->opaque->png_ptr;
2958 int passes;
2959
2960 /* Called when the libpng data must be transformed into the color-mapped
2961 * form. There is a local row buffer in display->local and this routine must
2962 * do the interlace handling.
2963 */
2964 switch (png_ptr->interlaced)
2965 {
2966 case PNG_INTERLACE_NONE:
2967 passes = 1;
2968 break;
2969
2970 case PNG_INTERLACE_ADAM7:
2971 passes = PNG_INTERLACE_ADAM7_PASSES;
2972 break;
2973
2974 default:
2975 png_error(png_ptr, "unknown interlace type");
2976 }
2977
2978 {
2979 png_uint_32 height = image->height;
2980 png_uint_32 width = image->width;
2981 int proc = display->colormap_processing;
2982 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
2983 ptrdiff_t step_row = display->row_bytes;
2984 int pass;
2985
2986 for (pass = 0; pass < passes; ++pass)
2987 {
2988 unsigned int startx, stepx, stepy;
2989 png_uint_32 y;
2990
2991 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
2992 {
2993 /* The row may be empty for a short image: */
2994 if (PNG_PASS_COLS(width, pass) == 0)
2995 continue;
2996
2997 startx = PNG_PASS_START_COL(pass);
2998 stepx = PNG_PASS_COL_OFFSET(pass);
2999 y = PNG_PASS_START_ROW(pass);
3000 stepy = PNG_PASS_ROW_OFFSET(pass);
3001 }
3002
3003 else
3004 {
3005 y = 0;
3006 startx = 0;
3007 stepx = stepy = 1;
3008 }
3009
3010 for (; y<height; y += stepy)
3011 {
3012 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3013 png_bytep outrow = first_row + y * step_row;
3014 png_const_bytep end_row = outrow + width;
3015
3016 /* Read read the libpng data into the temporary buffer. */
3017 png_read_row(png_ptr, inrow, NULL);
3018
3019 /* Now process the row according to the processing option, note
3020 * that the caller verifies that the format of the libpng output
3021 * data is as required.
3022 */
3023 outrow += startx;
3024 switch (proc)
3025 {
3026 case PNG_CMAP_GA:
3027 for (; outrow < end_row; outrow += stepx)
3028 {
3029 /* The data is always in the PNG order */
3030 unsigned int gray = *inrow++;
3031 unsigned int alpha = *inrow++;
3032 unsigned int entry;
3033
3034 /* NOTE: this code is copied as a comment in
3035 * make_ga_colormap above. Please update the
3036 * comment if you change this code!
3037 */
3038 if (alpha > 229) /* opaque */
3039 {
3040 entry = (231 * gray + 128) >> 8;
3041 }
3042 else if (alpha < 26) /* transparent */
3043 {
3044 entry = 231;
3045 }
3046 else /* partially opaque */
3047 {
3048 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3049 }
3050
3051 *outrow = (png_byte)entry;
3052 }
3053 break;
3054
3055 case PNG_CMAP_TRANS:
3056 for (; outrow < end_row; outrow += stepx)
3057 {
3058 png_byte gray = *inrow++;
3059 png_byte alpha = *inrow++;
3060
3061 if (alpha == 0)
3062 *outrow = PNG_CMAP_TRANS_BACKGROUND;
3063
3064 else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3065 *outrow = gray;
3066
3067 else
3068 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3069 }
3070 break;
3071
3072 case PNG_CMAP_RGB:
3073 for (; outrow < end_row; outrow += stepx)
3074 {
3075 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3076 inrow += 3;
3077 }
3078 break;
3079
3080 case PNG_CMAP_RGB_ALPHA:
3081 for (; outrow < end_row; outrow += stepx)
3082 {
3083 unsigned int alpha = inrow[3];
3084
3085 /* Because the alpha entries only hold alpha==0.5 values
3086 * split the processing at alpha==0.25 (64) and 0.75
3087 * (196).
3088 */
3089
3090 if (alpha >= 196)
3091 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3092 inrow[2]);
3093
3094 else if (alpha < 64)
3095 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3096
3097 else
3098 {
3099 /* Likewise there are three entries for each of r, g
3100 * and b. We could select the entry by popcount on
3101 * the top two bits on those architectures that
3102 * support it, this is what the code below does,
3103 * crudely.
3104 */
3105 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3106
3107 /* Here are how the values map:
3108 *
3109 * 0x00 .. 0x3f -> 0
3110 * 0x40 .. 0xbf -> 1
3111 * 0xc0 .. 0xff -> 2
3112 *
3113 * So, as above with the explicit alpha checks, the
3114 * breakpoints are at 64 and 196.
3115 */
3116 if (inrow[0] & 0x80) back_i += 9; /* red */
3117 if (inrow[0] & 0x40) back_i += 9;
3118 if (inrow[0] & 0x80) back_i += 3; /* green */
3119 if (inrow[0] & 0x40) back_i += 3;
3120 if (inrow[0] & 0x80) back_i += 1; /* blue */
3121 if (inrow[0] & 0x40) back_i += 1;
3122
3123 *outrow = (png_byte)back_i;
3124 }
3125
3126 inrow += 4;
3127 }
3128 break;
3129
3130 default:
3131 break;
3132 }
3133 }
3134 }
3135 }
3136
3137 return 1;
3138 }
3139
3140 static int
3141 png_image_read_colormapped(png_voidp argument)
3142 {
3143 png_image_read_control *display = png_voidcast(png_image_read_control*,
3144 argument);
3145 png_imagep image = display->image;
3146 png_controlp control = image->opaque;
3147 png_structrp png_ptr = control->png_ptr;
3148 png_inforp info_ptr = control->info_ptr;
3149
3150 int passes = 0; /* As a flag */
3151
3152 PNG_SKIP_CHUNKS(png_ptr);
3153
3154 /* Update the 'info' structure and make sure the result is as required; first
3155 * make sure to turn on the interlace handling if it will be required
3156 * (because it can't be turned on *after* the call to png_read_update_info!)
3157 */
3158 if (display->colormap_processing == PNG_CMAP_NONE)
3159 passes = png_set_interlace_handling(png_ptr);
3160
3161 png_read_update_info(png_ptr, info_ptr);
3162
3163 /* The expected output can be deduced from the colormap_processing option. */
3164 switch (display->colormap_processing)
3165 {
3166 case PNG_CMAP_NONE:
3167 /* Output must be one channel and one byte per pixel, the output
3168 * encoding can be anything.
3169 */
3170 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3171 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3172 info_ptr->bit_depth == 8)
3173 break;
3174
3175 goto bad_output;
3176
3177 case PNG_CMAP_TRANS:
3178 case PNG_CMAP_GA:
3179 /* Output must be two channels and the 'G' one must be sRGB, the latter
3180 * can be checked with an exact number because it should have been set
3181 * to this number above!
3182 */
3183 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3184 info_ptr->bit_depth == 8 &&
3185 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3186 image->colormap_entries == 256)
3187 break;
3188
3189 goto bad_output;
3190
3191 case PNG_CMAP_RGB:
3192 /* Output must be 8-bit sRGB encoded RGB */
3193 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3194 info_ptr->bit_depth == 8 &&
3195 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3196 image->colormap_entries == 216)
3197 break;
3198
3199 goto bad_output;
3200
3201 case PNG_CMAP_RGB_ALPHA:
3202 /* Output must be 8-bit sRGB encoded RGBA */
3203 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3204 info_ptr->bit_depth == 8 &&
3205 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3206 image->colormap_entries == 244 /* 216 + 1 + 27 */)
3207 break;
3208
3209 /* goto bad_output; */
3210 /* FALL THROUGH */
3211
3212 default:
3213 bad_output:
3214 png_error(png_ptr, "bad color-map processing (internal error)");
3215 }
3216
3217 /* Now read the rows. Do this here if it is possible to read directly into
3218 * the output buffer, otherwise allocate a local row buffer of the maximum
3219 * size libpng requires and call the relevant processing routine safely.
3220 */
3221 {
3222 png_voidp first_row = display->buffer;
3223 ptrdiff_t row_bytes = display->row_stride;
3224
3225 /* The following expression is designed to work correctly whether it gives
3226 * a signed or an unsigned result.
3227 */
3228 if (row_bytes < 0)
3229 {
3230 char *ptr = png_voidcast(char*, first_row);
3231 ptr += (image->height-1) * (-row_bytes);
3232 first_row = png_voidcast(png_voidp, ptr);
3233 }
3234
3235 display->first_row = first_row;
3236 display->row_bytes = row_bytes;
3237 }
3238
3239 if (passes == 0)
3240 {
3241 int result;
3242 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3243
3244 display->local_row = row;
3245 result = png_safe_execute(image, png_image_read_and_map, display);
3246 display->local_row = NULL;
3247 png_free(png_ptr, row);
3248
3249 return result;
3250 }
3251
3252 else
3253 {
3254 png_alloc_size_t row_bytes = display->row_bytes;
3255
3256 while (--passes >= 0)
3257 {
3258 png_uint_32 y = image->height;
3259 png_bytep row = png_voidcast(png_bytep, display->first_row);
3260
3261 while (y-- > 0)
3262 {
3263 png_read_row(png_ptr, row, NULL);
3264 row += row_bytes;
3265 }
3266 }
3267
3268 return 1;
3269 }
3270 }
3271
3272 /* Just the row reading part of png_image_read. */
3273 static int
3274 png_image_read_composite(png_voidp argument)
3275 {
3276 png_image_read_control *display = png_voidcast(png_image_read_control*,
3277 argument);
3278 png_imagep image = display->image;
3279 png_structrp png_ptr = image->opaque->png_ptr;
3280 int passes;
3281
3282 switch (png_ptr->interlaced)
3283 {
3284 case PNG_INTERLACE_NONE:
3285 passes = 1;
3286 break;
3287
3288 case PNG_INTERLACE_ADAM7:
3289 passes = PNG_INTERLACE_ADAM7_PASSES;
3290 break;
3291
3292 default:
3293 png_error(png_ptr, "unknown interlace type");
3294 }
3295
3296 {
3297 png_uint_32 height = image->height;
3298 png_uint_32 width = image->width;
3299 ptrdiff_t step_row = display->row_bytes;
3300 unsigned int channels =
3301 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3302 int pass;
3303
3304 for (pass = 0; pass < passes; ++pass)
3305 {
3306 unsigned int startx, stepx, stepy;
3307 png_uint_32 y;
3308
3309 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3310 {
3311 /* The row may be empty for a short image: */
3312 if (PNG_PASS_COLS(width, pass) == 0)
3313 continue;
3314
3315 startx = PNG_PASS_START_COL(pass) * channels;
3316 stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3317 y = PNG_PASS_START_ROW(pass);
3318 stepy = PNG_PASS_ROW_OFFSET(pass);
3319 }
3320
3321 else
3322 {
3323 y = 0;
3324 startx = 0;
3325 stepx = channels;
3326 stepy = 1;
3327 }
3328
3329 for (; y<height; y += stepy)
3330 {
3331 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3332 png_bytep outrow;
3333 png_const_bytep end_row;
3334
3335 /* Read the row, which is packed: */
3336 png_read_row(png_ptr, inrow, NULL);
3337
3338 outrow = png_voidcast(png_bytep, display->first_row);
3339 outrow += y * step_row;
3340 end_row = outrow + width * channels;
3341
3342 /* Now do the composition on each pixel in this row. */
3343 outrow += startx;
3344 for (; outrow < end_row; outrow += stepx)
3345 {
3346 png_byte alpha = inrow[channels];
3347
3348 if (alpha > 0) /* else no change to the output */
3349 {
3350 unsigned int c;
3351
3352 for (c=0; c<channels; ++c)
3353 {
3354 png_uint_32 component = inrow[c];
3355
3356 if (alpha < 255) /* else just use component */
3357 {
3358 /* This is PNG_OPTIMIZED_ALPHA, the component value
3359 * is a linear 8-bit value. Combine this with the
3360 * current outrow[c] value which is sRGB encoded.
3361 * Arithmetic here is 16-bits to preserve the output
3362 * values correctly.
3363 */
3364 component *= 257*255; /* =65535 */
3365 component += (255-alpha)*png_sRGB_table[outrow[c]];
3366
3367 /* So 'component' is scaled by 255*65535 and is
3368 * therefore appropriate for the sRGB to linear
3369 * conversion table.
3370 */
3371 component = PNG_sRGB_FROM_LINEAR(component);
3372 }
3373
3374 outrow[c] = (png_byte)component;
3375 }
3376 }
3377
3378 inrow += channels+1; /* components and alpha channel */
3379 }
3380 }
3381 }
3382 }
3383
3384 return 1;
3385 }
3386
3387 /* The do_local_background case; called when all the following transforms are to
3388 * be done:
3389 *
3390 * PNG_RGB_TO_GRAY
3391 * PNG_COMPOSITE
3392 * PNG_GAMMA
3393 *
3394 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3395 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3396 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3397 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3398 * row and handles the removal or pre-multiplication of the alpha channel.
3399 */
3400 static int
3401 png_image_read_background(png_voidp argument)
3402 {
3403 png_image_read_control *display = png_voidcast(png_image_read_control*,
3404 argument);
3405 png_imagep image = display->image;
3406 png_structrp png_ptr = image->opaque->png_ptr;
3407 png_inforp info_ptr = image->opaque->info_ptr;
3408 png_uint_32 height = image->height;
3409 png_uint_32 width = image->width;
3410 int pass, passes;
3411
3412 /* Double check the convoluted logic below. We expect to get here with
3413 * libpng doing rgb to gray and gamma correction but background processing
3414 * left to the png_image_read_background function. The rows libpng produce
3415 * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3416 */
3417 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3418 png_error(png_ptr, "lost rgb to gray");
3419
3420 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3421 png_error(png_ptr, "unexpected compose");
3422
3423 if (png_get_channels(png_ptr, info_ptr) != 2)
3424 png_error(png_ptr, "lost/gained channels");
3425
3426 /* Expect the 8-bit case to always remove the alpha channel */
3427 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3428 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3429 png_error(png_ptr, "unexpected 8-bit transformation");
3430
3431 switch (png_ptr->interlaced)
3432 {
3433 case PNG_INTERLACE_NONE:
3434 passes = 1;
3435 break;
3436
3437 case PNG_INTERLACE_ADAM7:
3438 passes = PNG_INTERLACE_ADAM7_PASSES;
3439 break;
3440
3441 default:
3442 png_error(png_ptr, "unknown interlace type");
3443 }
3444
3445 /* Use direct access to info_ptr here because otherwise the simplified API
3446 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3447 * checking the value after libpng expansions, not the original value in the
3448 * PNG.
3449 */
3450 switch (info_ptr->bit_depth)
3451 {
3452 case 8:
3453 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3454 * to be removed by composing on a background: either the row if
3455 * display->background is NULL or display->background->green if not.
3456 * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3457 */
3458 {
3459 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3460 ptrdiff_t step_row = display->row_bytes;
3461
3462 for (pass = 0; pass < passes; ++pass)
3463 {
3464 png_bytep row = png_voidcast(png_bytep,
3465 display->first_row);
3466 unsigned int startx, stepx, stepy;
3467 png_uint_32 y;
3468
3469 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3470 {
3471 /* The row may be empty for a short image: */
3472 if (PNG_PASS_COLS(width, pass) == 0)
3473 continue;
3474
3475 startx = PNG_PASS_START_COL(pass);
3476 stepx = PNG_PASS_COL_OFFSET(pass);
3477 y = PNG_PASS_START_ROW(pass);
3478 stepy = PNG_PASS_ROW_OFFSET(pass);
3479 }
3480
3481 else
3482 {
3483 y = 0;
3484 startx = 0;
3485 stepx = stepy = 1;
3486 }
3487
3488 if (display->background == NULL)
3489 {
3490 for (; y<height; y += stepy)
3491 {
3492 png_bytep inrow = png_voidcast(png_bytep,
3493 display->local_row);
3494 png_bytep outrow = first_row + y * step_row;
3495 png_const_bytep end_row = outrow + width;
3496
3497 /* Read the row, which is packed: */
3498 png_read_row(png_ptr, inrow, NULL);
3499
3500 /* Now do the composition on each pixel in this row. */
3501 outrow += startx;
3502 for (; outrow < end_row; outrow += stepx)
3503 {
3504 png_byte alpha = inrow[1];
3505
3506 if (alpha > 0) /* else no change to the output */
3507 {
3508 png_uint_32 component = inrow[0];
3509
3510 if (alpha < 255) /* else just use component */
3511 {
3512 /* Since PNG_OPTIMIZED_ALPHA was not set it is
3513 * necessary to invert the sRGB transfer
3514 * function and multiply the alpha out.
3515 */
3516 component = png_sRGB_table[component] * alpha;
3517 component += png_sRGB_table[outrow[0]] *
3518 (255-alpha);
3519 component = PNG_sRGB_FROM_LINEAR(component);
3520 }
3521
3522 outrow[0] = (png_byte)component;
3523 }
3524
3525 inrow += 2; /* gray and alpha channel */
3526 }
3527 }
3528 }
3529
3530 else /* constant background value */
3531 {
3532 png_byte background8 = display->background->green;
3533 png_uint_16 background = png_sRGB_table[background8];
3534
3535 for (; y<height; y += stepy)
3536 {
3537 png_bytep inrow = png_voidcast(png_bytep,
3538 display->local_row);
3539 png_bytep outrow = first_row + y * step_row;
3540 png_const_bytep end_row = outrow + width;
3541
3542 /* Read the row, which is packed: */
3543 png_read_row(png_ptr, inrow, NULL);
3544
3545 /* Now do the composition on each pixel in this row. */
3546 outrow += startx;
3547 for (; outrow < end_row; outrow += stepx)
3548 {
3549 png_byte alpha = inrow[1];
3550
3551 if (alpha > 0) /* else use background */
3552 {
3553 png_uint_32 component = inrow[0];
3554
3555 if (alpha < 255) /* else just use component */
3556 {
3557 component = png_sRGB_table[component] * alpha;
3558 component += background * (255-alpha);
3559 component = PNG_sRGB_FROM_LINEAR(component);
3560 }
3561
3562 outrow[0] = (png_byte)component;
3563 }
3564
3565 else
3566 outrow[0] = background8;
3567
3568 inrow += 2; /* gray and alpha channel */
3569 }
3570
3571 row += display->row_bytes;
3572 }
3573 }
3574 }
3575 }
3576 break;
3577
3578 case 16:
3579 /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3580 * still be done and, maybe, the alpha channel removed. This code also
3581 * handles the alpha-first option.
3582 */
3583 {
3584 png_uint_16p first_row = png_voidcast(png_uint_16p,
3585 display->first_row);
3586 /* The division by two is safe because the caller passed in a
3587 * stride which was multiplied by 2 (below) to get row_bytes.
3588 */
3589 ptrdiff_t step_row = display->row_bytes / 2;
3590 int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
3591 unsigned int outchannels = 1+preserve_alpha;
3592 int swap_alpha = 0;
3593
3594 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3595 if (preserve_alpha != 0 &&
3596 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3597 swap_alpha = 1;
3598 # endif
3599
3600 for (pass = 0; pass < passes; ++pass)
3601 {
3602 unsigned int startx, stepx, stepy;
3603 png_uint_32 y;
3604
3605 /* The 'x' start and step are adjusted to output components here.
3606 */
3607 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3608 {
3609 /* The row may be empty for a short image: */
3610 if (PNG_PASS_COLS(width, pass) == 0)
3611 continue;
3612
3613 startx = PNG_PASS_START_COL(pass) * outchannels;
3614 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3615 y = PNG_PASS_START_ROW(pass);
3616 stepy = PNG_PASS_ROW_OFFSET(pass);
3617 }
3618
3619 else
3620 {
3621 y = 0;
3622 startx = 0;
3623 stepx = outchannels;
3624 stepy = 1;
3625 }
3626
3627 for (; y<height; y += stepy)
3628 {
3629 png_const_uint_16p inrow;
3630 png_uint_16p outrow = first_row + y*step_row;
3631 png_uint_16p end_row = outrow + width * outchannels;
3632
3633 /* Read the row, which is packed: */
3634 png_read_row(png_ptr, png_voidcast(png_bytep,
3635 display->local_row), NULL);
3636 inrow = png_voidcast(png_const_uint_16p, display->local_row);
3637
3638 /* Now do the pre-multiplication on each pixel in this row.
3639 */
3640 outrow += startx;
3641 for (; outrow < end_row; outrow += stepx)
3642 {
3643 png_uint_32 component = inrow[0];
3644 png_uint_16 alpha = inrow[1];
3645
3646 if (alpha > 0) /* else 0 */
3647 {
3648 if (alpha < 65535) /* else just use component */
3649 {
3650 component *= alpha;
3651 component += 32767;
3652 component /= 65535;
3653 }
3654 }
3655
3656 else
3657 component = 0;
3658
3659 outrow[swap_alpha] = (png_uint_16)component;
3660 if (preserve_alpha != 0)
3661 outrow[1 ^ swap_alpha] = alpha;
3662
3663 inrow += 2; /* components and alpha channel */
3664 }
3665 }
3666 }
3667 }
3668 break;
3669
3670 #ifdef __GNUC__
3671 default:
3672 png_error(png_ptr, "unexpected bit depth");
3673 #endif
3674 }
3675
3676 return 1;
3677 }
3678
3679 /* The guts of png_image_finish_read as a png_safe_execute callback. */
3680 static int
3681 png_image_read_direct(png_voidp argument)
3682 {
3683 png_image_read_control *display = png_voidcast(png_image_read_control*,
3684 argument);
3685 png_imagep image = display->image;
3686 png_structrp png_ptr = image->opaque->png_ptr;
3687 png_inforp info_ptr = image->opaque->info_ptr;
3688
3689 png_uint_32 format = image->format;
3690 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3691 int do_local_compose = 0;
3692 int do_local_background = 0; /* to avoid double gamma correction bug */
3693 int passes = 0;
3694
3695 /* Add transforms to ensure the correct output format is produced then check
3696 * that the required implementation support is there. Always expand; always
3697 * need 8 bits minimum, no palette and expanded tRNS.
3698 */
3699 png_set_expand(png_ptr);
3700
3701 /* Now check the format to see if it was modified. */
3702 {
3703 png_uint_32 base_format = png_image_format(png_ptr) &
3704 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3705 png_uint_32 change = format ^ base_format;
3706 png_fixed_point output_gamma;
3707 int mode; /* alpha mode */
3708
3709 /* Do this first so that we have a record if rgb to gray is happening. */
3710 if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3711 {
3712 /* gray<->color transformation required. */
3713 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3714 png_set_gray_to_rgb(png_ptr);
3715
3716 else
3717 {
3718 /* libpng can't do both rgb to gray and
3719 * background/pre-multiplication if there is also significant gamma
3720 * correction, because both operations require linear colors and
3721 * the code only supports one transform doing the gamma correction.
3722 * Handle this by doing the pre-multiplication or background
3723 * operation in this code, if necessary.
3724 *
3725 * TODO: fix this by rewriting pngrtran.c (!)
3726 *
3727 * For the moment (given that fixing this in pngrtran.c is an
3728 * enormous change) 'do_local_background' is used to indicate that
3729 * the problem exists.
3730 */
3731 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3732 do_local_background = 1/*maybe*/;
3733
3734 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3735 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3736 }
3737
3738 change &= ~PNG_FORMAT_FLAG_COLOR;
3739 }
3740
3741 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3742 */
3743 {
3744 png_fixed_point input_gamma_default;
3745
3746 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3747 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3748 input_gamma_default = PNG_GAMMA_LINEAR;
3749 else
3750 input_gamma_default = PNG_DEFAULT_sRGB;
3751
3752 /* Call png_set_alpha_mode to set the default for the input gamma; the
3753 * output gamma is set by a second call below.
3754 */
3755 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3756 }
3757
3758 if (linear != 0)
3759 {
3760 /* If there *is* an alpha channel in the input it must be multiplied
3761 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3762 */
3763 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3764 mode = PNG_ALPHA_STANDARD; /* associated alpha */
3765
3766 else
3767 mode = PNG_ALPHA_PNG;
3768
3769 output_gamma = PNG_GAMMA_LINEAR;
3770 }
3771
3772 else
3773 {
3774 mode = PNG_ALPHA_PNG;
3775 output_gamma = PNG_DEFAULT_sRGB;
3776 }
3777
3778 /* If 'do_local_background' is set check for the presence of gamma
3779 * correction; this is part of the work-round for the libpng bug
3780 * described above.
3781 *
3782 * TODO: fix libpng and remove this.
3783 */
3784 if (do_local_background != 0)
3785 {
3786 png_fixed_point gtest;
3787
3788 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3789 * gamma correction, the screen gamma hasn't been set on png_struct
3790 * yet; it's set below. png_struct::gamma, however, is set to the
3791 * final value.
3792 */
3793 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
3794 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3795 do_local_background = 0;
3796
3797 else if (mode == PNG_ALPHA_STANDARD)
3798 {
3799 do_local_background = 2/*required*/;
3800 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
3801 }
3802
3803 /* else leave as 1 for the checks below */
3804 }
3805
3806 /* If the bit-depth changes then handle that here. */
3807 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
3808 {
3809 if (linear != 0 /*16-bit output*/)
3810 png_set_expand_16(png_ptr);
3811
3812 else /* 8-bit output */
3813 png_set_scale_16(png_ptr);
3814
3815 change &= ~PNG_FORMAT_FLAG_LINEAR;
3816 }
3817
3818 /* Now the background/alpha channel changes. */
3819 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
3820 {
3821 /* Removing an alpha channel requires composition for the 8-bit
3822 * formats; for the 16-bit it is already done, above, by the
3823 * pre-multiplication and the channel just needs to be stripped.
3824 */
3825 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3826 {
3827 /* If RGB->gray is happening the alpha channel must be left and the
3828 * operation completed locally.
3829 *
3830 * TODO: fix libpng and remove this.
3831 */
3832 if (do_local_background != 0)
3833 do_local_background = 2/*required*/;
3834
3835 /* 16-bit output: just remove the channel */
3836 else if (linear != 0) /* compose on black (well, pre-multiply) */
3837 png_set_strip_alpha(png_ptr);
3838
3839 /* 8-bit output: do an appropriate compose */
3840 else if (display->background != NULL)
3841 {
3842 png_color_16 c;
3843
3844 c.index = 0; /*unused*/
3845 c.red = display->background->red;
3846 c.green = display->background->green;
3847 c.blue = display->background->blue;
3848 c.gray = display->background->green;
3849
3850 /* This is always an 8-bit sRGB value, using the 'green' channel
3851 * for gray is much better than calculating the luminance here;
3852 * we can get off-by-one errors in that calculation relative to
3853 * the app expectations and that will show up in transparent
3854 * pixels.
3855 */
3856 png_set_background_fixed(png_ptr, &c,
3857 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3858 0/*gamma: not used*/);
3859 }
3860
3861 else /* compose on row: implemented below. */
3862 {
3863 do_local_compose = 1;
3864 /* This leaves the alpha channel in the output, so it has to be
3865 * removed by the code below. Set the encoding to the 'OPTIMIZE'
3866 * one so the code only has to hack on the pixels that require
3867 * composition.
3868 */
3869 mode = PNG_ALPHA_OPTIMIZED;
3870 }
3871 }
3872
3873 else /* output needs an alpha channel */
3874 {
3875 /* This is tricky because it happens before the swap operation has
3876 * been accomplished; however, the swap does *not* swap the added
3877 * alpha channel (weird API), so it must be added in the correct
3878 * place.
3879 */
3880 png_uint_32 filler; /* opaque filler */
3881 int where;
3882
3883 if (linear != 0)
3884 filler = 65535;
3885
3886 else
3887 filler = 255;
3888
3889 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
3890 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3891 {
3892 where = PNG_FILLER_BEFORE;
3893 change &= ~PNG_FORMAT_FLAG_AFIRST;
3894 }
3895
3896 else
3897 #endif
3898 where = PNG_FILLER_AFTER;
3899
3900 png_set_add_alpha(png_ptr, filler, where);
3901 }
3902
3903 /* This stops the (irrelevant) call to swap_alpha below. */
3904 change &= ~PNG_FORMAT_FLAG_ALPHA;
3905 }
3906
3907 /* Now set the alpha mode correctly; this is always done, even if there is
3908 * no alpha channel in either the input or the output because it correctly
3909 * sets the output gamma.
3910 */
3911 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
3912
3913 # ifdef PNG_FORMAT_BGR_SUPPORTED
3914 if ((change & PNG_FORMAT_FLAG_BGR) != 0)
3915 {
3916 /* Check only the output format; PNG is never BGR; don't do this if
3917 * the output is gray, but fix up the 'format' value in that case.
3918 */
3919 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3920 png_set_bgr(png_ptr);
3921
3922 else
3923 format &= ~PNG_FORMAT_FLAG_BGR;
3924
3925 change &= ~PNG_FORMAT_FLAG_BGR;
3926 }
3927 # endif
3928
3929 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3930 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
3931 {
3932 /* Only relevant if there is an alpha channel - it's particularly
3933 * important to handle this correctly because do_local_compose may
3934 * be set above and then libpng will keep the alpha channel for this
3935 * code to remove.
3936 */
3937 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
3938 {
3939 /* Disable this if doing a local background,
3940 * TODO: remove this when local background is no longer required.
3941 */
3942 if (do_local_background != 2)
3943 png_set_swap_alpha(png_ptr);
3944 }
3945
3946 else
3947 format &= ~PNG_FORMAT_FLAG_AFIRST;
3948
3949 change &= ~PNG_FORMAT_FLAG_AFIRST;
3950 }
3951 # endif
3952
3953 /* If the *output* is 16-bit then we need to check for a byte-swap on this
3954 * architecture.
3955 */
3956 if (linear != 0)
3957 {
3958 PNG_CONST png_uint_16 le = 0x0001;
3959
3960 if ((*(png_const_bytep) & le) != 0)
3961 png_set_swap(png_ptr);
3962 }
3963
3964 /* If change is not now 0 some transformation is missing - error out. */
3965 if (change != 0)
3966 png_error(png_ptr, "png_read_image: unsupported transformation");
3967 }
3968
3969 PNG_SKIP_CHUNKS(png_ptr);
3970
3971 /* Update the 'info' structure and make sure the result is as required; first
3972 * make sure to turn on the interlace handling if it will be required
3973 * (because it can't be turned on *after* the call to png_read_update_info!)
3974 *
3975 * TODO: remove the do_local_background fixup below.
3976 */
3977 if (do_local_compose == 0 && do_local_background != 2)
3978 passes = png_set_interlace_handling(png_ptr);
3979
3980 png_read_update_info(png_ptr, info_ptr);
3981
3982 {
3983 png_uint_32 info_format = 0;
3984
3985 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
3986 info_format |= PNG_FORMAT_FLAG_COLOR;
3987
3988 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
3989 {
3990 /* do_local_compose removes this channel below. */
3991 if (do_local_compose == 0)
3992 {
3993 /* do_local_background does the same if required. */
3994 if (do_local_background != 2 ||
3995 (format & PNG_FORMAT_FLAG_ALPHA) != 0)
3996 info_format |= PNG_FORMAT_FLAG_ALPHA;
3997 }
3998 }
3999
4000 else if (do_local_compose != 0) /* internal error */
4001 png_error(png_ptr, "png_image_read: alpha channel lost");
4002
4003 if (info_ptr->bit_depth == 16)
4004 info_format |= PNG_FORMAT_FLAG_LINEAR;
4005
4006 #ifdef PNG_FORMAT_BGR_SUPPORTED
4007 if ((png_ptr->transformations & PNG_BGR) != 0)
4008 info_format |= PNG_FORMAT_FLAG_BGR;
4009 #endif
4010
4011 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4012 if (do_local_background == 2)
4013 {
4014 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4015 info_format |= PNG_FORMAT_FLAG_AFIRST;
4016 }
4017
4018 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4019 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4020 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4021 {
4022 if (do_local_background == 2)
4023 png_error(png_ptr, "unexpected alpha swap transformation");
4024
4025 info_format |= PNG_FORMAT_FLAG_AFIRST;
4026 }
4027 # endif
4028
4029 /* This is actually an internal error. */
4030 if (info_format != format)
4031 png_error(png_ptr, "png_read_image: invalid transformations");
4032 }
4033
4034 /* Now read the rows. If do_local_compose is set then it is necessary to use
4035 * a local row buffer. The output will be GA, RGBA or BGRA and must be
4036 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
4037 * display acts as a flag.
4038 */
4039 {
4040 png_voidp first_row = display->buffer;
4041 ptrdiff_t row_bytes = display->row_stride;
4042
4043 if (linear != 0)
4044 row_bytes *= 2;
4045
4046 /* The following expression is designed to work correctly whether it gives
4047 * a signed or an unsigned result.
4048 */
4049 if (row_bytes < 0)
4050 {
4051 char *ptr = png_voidcast(char*, first_row);
4052 ptr += (image->height-1) * (-row_bytes);
4053 first_row = png_voidcast(png_voidp, ptr);
4054 }
4055
4056 display->first_row = first_row;
4057 display->row_bytes = row_bytes;
4058 }
4059
4060 if (do_local_compose != 0)
4061 {
4062 int result;
4063 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4064
4065 display->local_row = row;
4066 result = png_safe_execute(image, png_image_read_composite, display);
4067 display->local_row = NULL;
4068 png_free(png_ptr, row);
4069
4070 return result;
4071 }
4072
4073 else if (do_local_background == 2)
4074 {
4075 int result;
4076 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4077
4078 display->local_row = row;
4079 result = png_safe_execute(image, png_image_read_background, display);
4080 display->local_row = NULL;
4081 png_free(png_ptr, row);
4082
4083 return result;
4084 }
4085
4086 else
4087 {
4088 png_alloc_size_t row_bytes = display->row_bytes;
4089
4090 while (--passes >= 0)
4091 {
4092 png_uint_32 y = image->height;
4093 png_bytep row = png_voidcast(png_bytep, display->first_row);
4094
4095 while (y-- > 0)
4096 {
4097 png_read_row(png_ptr, row, NULL);
4098 row += row_bytes;
4099 }
4100 }
4101
4102 return 1;
4103 }
4104 }
4105
4106 int PNGAPI
4107 png_image_finish_read(png_imagep image, png_const_colorp background,
4108 void *buffer, png_int_32 row_stride, void *colormap)
4109 {
4110 if (image != NULL && image->version == PNG_IMAGE_VERSION)
4111 {
4112 /* Check for row_stride overflow. This check is not performed on the
4113 * original PNG format because it may not occur in the output PNG format
4114 * and libpng deals with the issues of reading the original.
4115 */
4116 const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4117
4118 if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
4119 {
4120 png_uint_32 check;
4121 const png_uint_32 png_row_stride = image->width * channels;
4122
4123 if (row_stride == 0)
4124 row_stride = (png_int_32)/*SAFE*/png_row_stride;
4125
4126 if (row_stride < 0)
4127 check = -row_stride;
4128
4129 else
4130 check = row_stride;
4131
4132 if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4133 {
4134 /* Now check for overflow of the image buffer calculation; this
4135 * limits the whole image size to 32 bits for API compatibility with
4136 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4137 */
4138 if (image->height <= 0xFFFFFFFF/png_row_stride)
4139 {
4140 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4141 (image->colormap_entries > 0 && colormap != NULL))
4142 {
4143 int result;
4144 png_image_read_control display;
4145
4146 memset(&display, 0, (sizeof display));
4147 display.image = image;
4148 display.buffer = buffer;
4149 display.row_stride = row_stride;
4150 display.colormap = colormap;
4151 display.background = background;
4152 display.local_row = NULL;
4153
4154 /* Choose the correct 'end' routine; for the color-map case
4155 * all the setup has already been done.
4156 */
4157 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4158 result = png_safe_execute(image,
4159 png_image_read_colormap, &display) &&
4160 png_safe_execute(image,
4161 png_image_read_colormapped, &display);
4162
4163 else
4164 result =
4165 png_safe_execute(image,
4166 png_image_read_direct, &display);
4167
4168 png_image_free(image);
4169 return result;
4170 }
4171
4172 else
4173 return png_image_error(image,
4174 "png_image_finish_read[color-map]: no color-map");
4175 }
4176
4177 else
4178 return png_image_error(image,
4179 "png_image_finish_read: image too large");
4180 }
4181
4182 else
4183 return png_image_error(image,
4184 "png_image_finish_read: invalid argument");
4185 }
4186
4187 else
4188 return png_image_error(image,
4189 "png_image_finish_read: row_stride too large");
4190 }
4191
4192 else if (image != NULL)
4193 return png_image_error(image,
4194 "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4195
4196 return 0;
4197 }
4198
4199 #endif /* SIMPLIFIED_READ */
4200 #endif /* READ */