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 1.6.26 [October 20, 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 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
391 png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
392 png_uint_32 s2 = (png_uint_32)(*(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, voidp params)
1062 {
1063 if (png_ptr == NULL || info_ptr == NULL)
1064 return;
1065
1066 /* png_read_info() gives us all of the information from the
1067 * PNG file before the first IDAT (image data chunk).
1068 */
1069 png_read_info(png_ptr, info_ptr);
1070 if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1071 png_error(png_ptr, "Image is too high to process with png_read_png()");
1072
1073 /* -------------- image transformations start here ------------------- */
1074 /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1075 * is not implemented. This will only happen in de-configured (non-default)
1076 * libpng builds. The results can be unexpected - png_read_png may return
1077 * short or mal-formed rows because the transform is skipped.
1078 */
1079
1080 /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1081 */
1082 if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1083 /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1084 * did in earlier versions, while "scale_16" is now more accurate.
1085 */
1086 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1087 png_set_scale_16(png_ptr);
1088 #else
1089 png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1090 #endif
1091
1092 /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1093 * latter by doing SCALE first. This is ok and allows apps not to check for
1094 * which is supported to get the right answer.
1095 */
1096 if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1097 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1098 png_set_strip_16(png_ptr);
1099 #else
1100 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1101 #endif
1102
1103 /* Strip alpha bytes from the input data without combining with
1104 * the background (not recommended).
1105 */
1106 if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1107 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1108 png_set_strip_alpha(png_ptr);
1109 #else
1110 png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1111 #endif
1112
1113 /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1114 * byte into separate bytes (useful for paletted and grayscale images).
1115 */
1116 if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1117 #ifdef PNG_READ_PACK_SUPPORTED
1118 png_set_packing(png_ptr);
1119 #else
1120 png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1121 #endif
1122
1123 /* Change the order of packed pixels to least significant bit first
1124 * (not useful if you are using png_set_packing).
1125 */
1126 if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1127 #ifdef PNG_READ_PACKSWAP_SUPPORTED
1128 png_set_packswap(png_ptr);
1129 #else
1130 png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1131 #endif
1132
1133 /* Expand paletted colors into true RGB triplets
1134 * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1135 * Expand paletted or RGB images with transparency to full alpha
1136 * channels so the data will be available as RGBA quartets.
1137 */
1138 if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1139 #ifdef PNG_READ_EXPAND_SUPPORTED
1140 png_set_expand(png_ptr);
1141 #else
1142 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1143 #endif
1144
1145 /* We don't handle background color or gamma transformation or quantizing.
1146 */
1147
1148 /* Invert monochrome files to have 0 as white and 1 as black
1149 */
1150 if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1151 #ifdef PNG_READ_INVERT_SUPPORTED
1152 png_set_invert_mono(png_ptr);
1153 #else
1154 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1155 #endif
1156
1157 /* If you want to shift the pixel values from the range [0,255] or
1158 * [0,65535] to the original [0,7] or [0,31], or whatever range the
1159 * colors were originally in:
1160 */
1161 if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1162 #ifdef PNG_READ_SHIFT_SUPPORTED
1163 if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1164 png_set_shift(png_ptr, &info_ptr->sig_bit);
1165 #else
1166 png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1167 #endif
1168
1169 /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1170 if ((transforms & PNG_TRANSFORM_BGR) != 0)
1171 #ifdef PNG_READ_BGR_SUPPORTED
1172 png_set_bgr(png_ptr);
1173 #else
1174 png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1175 #endif
1176
1177 /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1178 if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1179 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1180 png_set_swap_alpha(png_ptr);
1181 #else
1182 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1183 #endif
1184
1185 /* Swap bytes of 16-bit files to least significant byte first */
1186 if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1187 #ifdef PNG_READ_SWAP_SUPPORTED
1188 png_set_swap(png_ptr);
1189 #else
1190 png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1191 #endif
1192
1193 /* Added at libpng-1.2.41 */
1194 /* Invert the alpha channel from opacity to transparency */
1195 if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1196 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1197 png_set_invert_alpha(png_ptr);
1198 #else
1199 png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1200 #endif
1201
1202 /* Added at libpng-1.2.41 */
1203 /* Expand grayscale image to RGB */
1204 if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1205 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1206 png_set_gray_to_rgb(png_ptr);
1207 #else
1208 png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1209 #endif
1210
1211 /* Added at libpng-1.5.4 */
1212 if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1213 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1214 png_set_expand_16(png_ptr);
1215 #else
1216 png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1217 #endif
1218
1219 /* We don't handle adding filler bytes */
1220
1221 /* We use png_read_image and rely on that for interlace handling, but we also
1222 * call png_read_update_info therefore must turn on interlace handling now:
1223 */
1224 (void)png_set_interlace_handling(png_ptr);
1225
1226 /* Optional call to gamma correct and add the background to the palette
1227 * and update info structure. REQUIRED if you are expecting libpng to
1228 * update the palette for you (i.e., you selected such a transform above).
1229 */
1230 png_read_update_info(png_ptr, info_ptr);
1231
1232 /* -------------- image transformations end here ------------------- */
1233
1234 png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1235 if (info_ptr->row_pointers == NULL)
1236 {
1237 png_uint_32 iptr;
1238
1239 info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1240 info_ptr->height * (sizeof (png_bytep))));
1241
1242 for (iptr=0; iptr<info_ptr->height; iptr++)
1243 info_ptr->row_pointers[iptr] = NULL;
1244
1245 info_ptr->free_me |= PNG_FREE_ROWS;
1246
1247 for (iptr = 0; iptr < info_ptr->height; iptr++)
1248 info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1249 png_malloc(png_ptr, info_ptr->rowbytes));
1250 }
1251
1252 png_read_image(png_ptr, info_ptr->row_pointers);
1253 info_ptr->valid |= PNG_INFO_IDAT;
1254
1255 /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1256 png_read_end(png_ptr, info_ptr);
1257
1258 PNG_UNUSED(params)
1259 }
1260 #endif /* INFO_IMAGE */
1261 #endif /* SEQUENTIAL_READ */
1262
1263 #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1264 /* SIMPLIFIED READ
1265 *
1266 * This code currently relies on the sequential reader, though it could easily
1267 * be made to work with the progressive one.
1268 */
1269 /* Arguments to png_image_finish_read: */
1270
1271 /* Encoding of PNG data (used by the color-map code) */
1272 # define P_NOTSET 0 /* File encoding not yet known */
1273 # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1274 # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1275 # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1276 # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1277
1278 /* Color-map processing: after libpng has run on the PNG image further
1279 * processing may be needed to convert the data to color-map indices.
1280 */
1281 #define PNG_CMAP_NONE 0
1282 #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1283 #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1284 #define PNG_CMAP_RGB 3 /* Process RGB data */
1285 #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1286
1287 /* The following document where the background is for each processing case. */
1288 #define PNG_CMAP_NONE_BACKGROUND 256
1289 #define PNG_CMAP_GA_BACKGROUND 231
1290 #define PNG_CMAP_TRANS_BACKGROUND 254
1291 #define PNG_CMAP_RGB_BACKGROUND 256
1292 #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1293
1294 typedef struct
1295 {
1296 /* Arguments: */
1297 png_imagep image;
1298 png_voidp buffer;
1299 png_int_32 row_stride;
1300 png_voidp colormap;
1301 png_const_colorp background;
1302 /* Local variables: */
1303 png_voidp local_row;
1304 png_voidp first_row;
1305 ptrdiff_t row_bytes; /* step between rows */
1306 int file_encoding; /* E_ values above */
1307 png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1308 int colormap_processing; /* PNG_CMAP_ values above */
1309 } png_image_read_control;
1310
1311 /* Do all the *safe* initialization - 'safe' means that png_error won't be
1312 * called, so setting up the jmp_buf is not required. This means that anything
1313 * called from here must *not* call png_malloc - it has to call png_malloc_warn
1314 * instead so that control is returned safely back to this routine.
1315 */
1316 static int
1317 png_image_read_init(png_imagep image)
1318 {
1319 if (image->opaque == NULL)
1320 {
1321 png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1322 png_safe_error, png_safe_warning);
1323
1324 /* And set the rest of the structure to NULL to ensure that the various
1325 * fields are consistent.
1326 */
1327 memset(image, 0, (sizeof *image));
1328 image->version = PNG_IMAGE_VERSION;
1329
1330 if (png_ptr != NULL)
1331 {
1332 png_infop info_ptr = png_create_info_struct(png_ptr);
1333
1334 if (info_ptr != NULL)
1335 {
1336 png_controlp control = png_voidcast(png_controlp,
1337 png_malloc_warn(png_ptr, (sizeof *control)));
1338
1339 if (control != NULL)
1340 {
1341 memset(control, 0, (sizeof *control));
1342
1343 control->png_ptr = png_ptr;
1344 control->info_ptr = info_ptr;
1345 control->for_write = 0;
1346
1347 image->opaque = control;
1348 return 1;
1349 }
1350
1351 /* Error clean up */
1352 png_destroy_info_struct(png_ptr, &info_ptr);
1353 }
1354
1355 png_destroy_read_struct(&png_ptr, NULL, NULL);
1356 }
1357
1358 return png_image_error(image, "png_image_read: out of memory");
1359 }
1360
1361 return png_image_error(image, "png_image_read: opaque pointer not NULL");
1362 }
1363
1364 /* Utility to find the base format of a PNG file from a png_struct. */
1365 static png_uint_32
1366 png_image_format(png_structrp png_ptr)
1367 {
1368 png_uint_32 format = 0;
1369
1370 if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1371 format |= PNG_FORMAT_FLAG_COLOR;
1372
1373 if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1374 format |= PNG_FORMAT_FLAG_ALPHA;
1375
1376 /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1377 * sets the png_struct fields; that's all we are interested in here. The
1378 * precise interaction with an app call to png_set_tRNS and PNG file reading
1379 * is unclear.
1380 */
1381 else if (png_ptr->num_trans > 0)
1382 format |= PNG_FORMAT_FLAG_ALPHA;
1383
1384 if (png_ptr->bit_depth == 16)
1385 format |= PNG_FORMAT_FLAG_LINEAR;
1386
1387 if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1388 format |= PNG_FORMAT_FLAG_COLORMAP;
1389
1390 return format;
1391 }
1392
1393 /* Is the given gamma significantly different from sRGB? The test is the same
1394 * one used in pngrtran.c when deciding whether to do gamma correction. The
1395 * arithmetic optimizes the division by using the fact that the inverse of the
1396 * file sRGB gamma is 2.2
1397 */
1398 static int
1399 png_gamma_not_sRGB(png_fixed_point g)
1400 {
1401 if (g < PNG_FP_1)
1402 {
1403 /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1404 if (g == 0)
1405 return 0;
1406
1407 return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1408 }
1409
1410 return 1;
1411 }
1412
1413 /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1414 * header and fill in all the information. This is executed in a safe context,
1415 * unlike the init routine above.
1416 */
1417 static int
1418 png_image_read_header(png_voidp argument)
1419 {
1420 png_imagep image = png_voidcast(png_imagep, argument);
1421 png_structrp png_ptr = image->opaque->png_ptr;
1422 png_inforp info_ptr = image->opaque->info_ptr;
1423
1424 #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1425 png_set_benign_errors(png_ptr, 1/*warn*/);
1426 #endif
1427 png_read_info(png_ptr, info_ptr);
1428
1429 /* Do this the fast way; just read directly out of png_struct. */
1430 image->width = png_ptr->width;
1431 image->height = png_ptr->height;
1432
1433 {
1434 png_uint_32 format = png_image_format(png_ptr);
1435
1436 image->format = format;
1437
1438 #ifdef PNG_COLORSPACE_SUPPORTED
1439 /* Does the colorspace match sRGB? If there is no color endpoint
1440 * (colorant) information assume yes, otherwise require the
1441 * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1442 * colorspace has been determined to be invalid ignore it.
1443 */
1444 if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1445 & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1446 PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1447 image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1448 #endif
1449 }
1450
1451 /* We need the maximum number of entries regardless of the format the
1452 * application sets here.
1453 */
1454 {
1455 png_uint_32 cmap_entries;
1456
1457 switch (png_ptr->color_type)
1458 {
1459 case PNG_COLOR_TYPE_GRAY:
1460 cmap_entries = 1U << png_ptr->bit_depth;
1461 break;
1462
1463 case PNG_COLOR_TYPE_PALETTE:
1464 cmap_entries = (png_uint_32)png_ptr->num_palette;
1465 break;
1466
1467 default:
1468 cmap_entries = 256;
1469 break;
1470 }
1471
1472 if (cmap_entries > 256)
1473 cmap_entries = 256;
1474
1475 image->colormap_entries = cmap_entries;
1476 }
1477
1478 return 1;
1479 }
1480
1481 #ifdef PNG_STDIO_SUPPORTED
1482 int PNGAPI
1483 png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1484 {
1485 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1486 {
1487 if (file != NULL)
1488 {
1489 if (png_image_read_init(image) != 0)
1490 {
1491 /* This is slightly evil, but png_init_io doesn't do anything other
1492 * than this and we haven't changed the standard IO functions so
1493 * this saves a 'safe' function.
1494 */
1495 image->opaque->png_ptr->io_ptr = file;
1496 return png_safe_execute(image, png_image_read_header, image);
1497 }
1498 }
1499
1500 else
1501 return png_image_error(image,
1502 "png_image_begin_read_from_stdio: invalid argument");
1503 }
1504
1505 else if (image != NULL)
1506 return png_image_error(image,
1507 "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1508
1509 return 0;
1510 }
1511
1512 int PNGAPI
1513 png_image_begin_read_from_file(png_imagep image, const char *file_name)
1514 {
1515 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1516 {
1517 if (file_name != NULL)
1518 {
1519 FILE *fp = fopen(file_name, "rb");
1520
1521 if (fp != NULL)
1522 {
1523 if (png_image_read_init(image) != 0)
1524 {
1525 image->opaque->png_ptr->io_ptr = fp;
1526 image->opaque->owned_file = 1;
1527 return png_safe_execute(image, png_image_read_header, image);
1528 }
1529
1530 /* Clean up: just the opened file. */
1531 (void)fclose(fp);
1532 }
1533
1534 else
1535 return png_image_error(image, strerror(errno));
1536 }
1537
1538 else
1539 return png_image_error(image,
1540 "png_image_begin_read_from_file: invalid argument");
1541 }
1542
1543 else if (image != NULL)
1544 return png_image_error(image,
1545 "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1546
1547 return 0;
1548 }
1549 #endif /* STDIO */
1550
1551 static void PNGCBAPI
1552 png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
1553 {
1554 if (png_ptr != NULL)
1555 {
1556 png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1557 if (image != NULL)
1558 {
1559 png_controlp cp = image->opaque;
1560 if (cp != NULL)
1561 {
1562 png_const_bytep memory = cp->memory;
1563 png_size_t size = cp->size;
1564
1565 if (memory != NULL && size >= need)
1566 {
1567 memcpy(out, memory, need);
1568 cp->memory = memory + need;
1569 cp->size = size - need;
1570 return;
1571 }
1572
1573 png_error(png_ptr, "read beyond end of data");
1574 }
1575 }
1576
1577 png_error(png_ptr, "invalid memory read");
1578 }
1579 }
1580
1581 int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1582 png_const_voidp memory, png_size_t size)
1583 {
1584 if (image != NULL && image->version == PNG_IMAGE_VERSION)
1585 {
1586 if (memory != NULL && size > 0)
1587 {
1588 if (png_image_read_init(image) != 0)
1589 {
1590 /* Now set the IO functions to read from the memory buffer and
1591 * store it into io_ptr. Again do this in-place to avoid calling a
1592 * libpng function that requires error handling.
1593 */
1594 image->opaque->memory = png_voidcast(png_const_bytep, memory);
1595 image->opaque->size = size;
1596 image->opaque->png_ptr->io_ptr = image;
1597 image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1598
1599 return png_safe_execute(image, png_image_read_header, image);
1600 }
1601 }
1602
1603 else
1604 return png_image_error(image,
1605 "png_image_begin_read_from_memory: invalid argument");
1606 }
1607
1608 else if (image != NULL)
1609 return png_image_error(image,
1610 "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1611
1612 return 0;
1613 }
1614
1615 /* Utility function to skip chunks that are not used by the simplified image
1616 * read functions and an appropriate macro to call it.
1617 */
1618 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1619 static void
1620 png_image_skip_unused_chunks(png_structrp png_ptr)
1621 {
1622 /* Prepare the reader to ignore all recognized chunks whose data will not
1623 * be used, i.e., all chunks recognized by libpng except for those
1624 * involved in basic image reading:
1625 *
1626 * IHDR, PLTE, IDAT, IEND
1627 *
1628 * Or image data handling:
1629 *
1630 * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1631 *
1632 * This provides a small performance improvement and eliminates any
1633 * potential vulnerability to security problems in the unused chunks.
1634 *
1635 * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1636 * too. This allows the simplified API to be compiled without iCCP support,
1637 * however if the support is there the chunk is still checked to detect
1638 * errors (which are unfortunately quite common.)
1639 */
1640 {
1641 static PNG_CONST png_byte chunks_to_process[] = {
1642 98, 75, 71, 68, '\0', /* bKGD */
1643 99, 72, 82, 77, '\0', /* cHRM */
1644 103, 65, 77, 65, '\0', /* gAMA */
1645 # ifdef PNG_READ_iCCP_SUPPORTED
1646 105, 67, 67, 80, '\0', /* iCCP */
1647 # endif
1648 115, 66, 73, 84, '\0', /* sBIT */
1649 115, 82, 71, 66, '\0', /* sRGB */
1650 };
1651
1652 /* Ignore unknown chunks and all other chunks except for the
1653 * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1654 */
1655 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1656 NULL, -1);
1657
1658 /* But do not ignore image data handling chunks */
1659 png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1660 chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1661 }
1662 }
1663
1664 # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1665 #else
1666 # define PNG_SKIP_CHUNKS(p) ((void)0)
1667 #endif /* HANDLE_AS_UNKNOWN */
1668
1669 /* The following macro gives the exact rounded answer for all values in the
1670 * range 0..255 (it actually divides by 51.2, but the rounding still generates
1671 * the correct numbers 0..5
1672 */
1673 #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1674
1675 /* Utility functions to make particular color-maps */
1676 static void
1677 set_file_encoding(png_image_read_control *display)
1678 {
1679 png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1680 if (png_gamma_significant(g) != 0)
1681 {
1682 if (png_gamma_not_sRGB(g) != 0)
1683 {
1684 display->file_encoding = P_FILE;
1685 display->gamma_to_linear = png_reciprocal(g);
1686 }
1687
1688 else
1689 display->file_encoding = P_sRGB;
1690 }
1691
1692 else
1693 display->file_encoding = P_LINEAR8;
1694 }
1695
1696 static unsigned int
1697 decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1698 {
1699 if (encoding == P_FILE) /* double check */
1700 encoding = display->file_encoding;
1701
1702 if (encoding == P_NOTSET) /* must be the file encoding */
1703 {
1704 set_file_encoding(display);
1705 encoding = display->file_encoding;
1706 }
1707
1708 switch (encoding)
1709 {
1710 case P_FILE:
1711 value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1712 break;
1713
1714 case P_sRGB:
1715 value = png_sRGB_table[value];
1716 break;
1717
1718 case P_LINEAR:
1719 break;
1720
1721 case P_LINEAR8:
1722 value *= 257;
1723 break;
1724
1725 #ifdef __GNUC__
1726 default:
1727 png_error(display->image->opaque->png_ptr,
1728 "unexpected encoding (internal error)");
1729 #endif
1730 }
1731
1732 return value;
1733 }
1734
1735 static png_uint_32
1736 png_colormap_compose(png_image_read_control *display,
1737 png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1738 png_uint_32 background, int encoding)
1739 {
1740 /* The file value is composed on the background, the background has the given
1741 * encoding and so does the result, the file is encoded with P_FILE and the
1742 * file and alpha are 8-bit values. The (output) encoding will always be
1743 * P_LINEAR or P_sRGB.
1744 */
1745 png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1746 png_uint_32 b = decode_gamma(display, background, encoding);
1747
1748 /* The alpha is always an 8-bit value (it comes from the palette), the value
1749 * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1750 */
1751 f = f * alpha + b * (255-alpha);
1752
1753 if (encoding == P_LINEAR)
1754 {
1755 /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1756 * accurate, it divides by 255.00000005937181414556, with no overflow.)
1757 */
1758 f *= 257; /* Now scaled by 65535 */
1759 f += f >> 16;
1760 f = (f+32768) >> 16;
1761 }
1762
1763 else /* P_sRGB */
1764 f = PNG_sRGB_FROM_LINEAR(f);
1765
1766 return f;
1767 }
1768
1769 /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1770 * be 8-bit.
1771 */
1772 static void
1773 png_create_colormap_entry(png_image_read_control *display,
1774 png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1775 png_uint_32 alpha, int encoding)
1776 {
1777 png_imagep image = display->image;
1778 const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1779 P_LINEAR : P_sRGB;
1780 const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1781 (red != green || green != blue);
1782
1783 if (ip > 255)
1784 png_error(image->opaque->png_ptr, "color-map index out of range");
1785
1786 /* Update the cache with whether the file gamma is significantly different
1787 * from sRGB.
1788 */
1789 if (encoding == P_FILE)
1790 {
1791 if (display->file_encoding == P_NOTSET)
1792 set_file_encoding(display);
1793
1794 /* Note that the cached value may be P_FILE too, but if it is then the
1795 * gamma_to_linear member has been set.
1796 */
1797 encoding = display->file_encoding;
1798 }
1799
1800 if (encoding == P_FILE)
1801 {
1802 png_fixed_point g = display->gamma_to_linear;
1803
1804 red = png_gamma_16bit_correct(red*257, g);
1805 green = png_gamma_16bit_correct(green*257, g);
1806 blue = png_gamma_16bit_correct(blue*257, g);
1807
1808 if (convert_to_Y != 0 || output_encoding == P_LINEAR)
1809 {
1810 alpha *= 257;
1811 encoding = P_LINEAR;
1812 }
1813
1814 else
1815 {
1816 red = PNG_sRGB_FROM_LINEAR(red * 255);
1817 green = PNG_sRGB_FROM_LINEAR(green * 255);
1818 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1819 encoding = P_sRGB;
1820 }
1821 }
1822
1823 else if (encoding == P_LINEAR8)
1824 {
1825 /* This encoding occurs quite frequently in test cases because PngSuite
1826 * includes a gAMA 1.0 chunk with most images.
1827 */
1828 red *= 257;
1829 green *= 257;
1830 blue *= 257;
1831 alpha *= 257;
1832 encoding = P_LINEAR;
1833 }
1834
1835 else if (encoding == P_sRGB &&
1836 (convert_to_Y != 0 || output_encoding == P_LINEAR))
1837 {
1838 /* The values are 8-bit sRGB values, but must be converted to 16-bit
1839 * linear.
1840 */
1841 red = png_sRGB_table[red];
1842 green = png_sRGB_table[green];
1843 blue = png_sRGB_table[blue];
1844 alpha *= 257;
1845 encoding = P_LINEAR;
1846 }
1847
1848 /* This is set if the color isn't gray but the output is. */
1849 if (encoding == P_LINEAR)
1850 {
1851 if (convert_to_Y != 0)
1852 {
1853 /* NOTE: these values are copied from png_do_rgb_to_gray */
1854 png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
1855 (png_uint_32)2366 * blue;
1856
1857 if (output_encoding == P_LINEAR)
1858 y = (y + 16384) >> 15;
1859
1860 else
1861 {
1862 /* y is scaled by 32768, we need it scaled by 255: */
1863 y = (y + 128) >> 8;
1864 y *= 255;
1865 y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
1866 alpha = PNG_DIV257(alpha);
1867 encoding = P_sRGB;
1868 }
1869
1870 blue = red = green = y;
1871 }
1872
1873 else if (output_encoding == P_sRGB)
1874 {
1875 red = PNG_sRGB_FROM_LINEAR(red * 255);
1876 green = PNG_sRGB_FROM_LINEAR(green * 255);
1877 blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1878 alpha = PNG_DIV257(alpha);
1879 encoding = P_sRGB;
1880 }
1881 }
1882
1883 if (encoding != output_encoding)
1884 png_error(image->opaque->png_ptr, "bad encoding (internal error)");
1885
1886 /* Store the value. */
1887 {
1888 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1889 const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1890 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
1891 # else
1892 # define afirst 0
1893 # endif
1894 # ifdef PNG_FORMAT_BGR_SUPPORTED
1895 const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1896 # else
1897 # define bgr 0
1898 # endif
1899
1900 if (output_encoding == P_LINEAR)
1901 {
1902 png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
1903
1904 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1905
1906 /* The linear 16-bit values must be pre-multiplied by the alpha channel
1907 * value, if less than 65535 (this is, effectively, composite on black
1908 * if the alpha channel is removed.)
1909 */
1910 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1911 {
1912 case 4:
1913 entry[afirst ? 0 : 3] = (png_uint_16)alpha;
1914 /* FALL THROUGH */
1915
1916 case 3:
1917 if (alpha < 65535)
1918 {
1919 if (alpha > 0)
1920 {
1921 blue = (blue * alpha + 32767U)/65535U;
1922 green = (green * alpha + 32767U)/65535U;
1923 red = (red * alpha + 32767U)/65535U;
1924 }
1925
1926 else
1927 red = green = blue = 0;
1928 }
1929 entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
1930 entry[afirst + 1] = (png_uint_16)green;
1931 entry[afirst + bgr] = (png_uint_16)red;
1932 break;
1933
1934 case 2:
1935 entry[1 ^ afirst] = (png_uint_16)alpha;
1936 /* FALL THROUGH */
1937
1938 case 1:
1939 if (alpha < 65535)
1940 {
1941 if (alpha > 0)
1942 green = (green * alpha + 32767U)/65535U;
1943
1944 else
1945 green = 0;
1946 }
1947 entry[afirst] = (png_uint_16)green;
1948 break;
1949
1950 default:
1951 break;
1952 }
1953 }
1954
1955 else /* output encoding is P_sRGB */
1956 {
1957 png_bytep entry = png_voidcast(png_bytep, display->colormap);
1958
1959 entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1960
1961 switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1962 {
1963 case 4:
1964 entry[afirst ? 0 : 3] = (png_byte)alpha;
1965 case 3:
1966 entry[afirst + (2 ^ bgr)] = (png_byte)blue;
1967 entry[afirst + 1] = (png_byte)green;
1968 entry[afirst + bgr] = (png_byte)red;
1969 break;
1970
1971 case 2:
1972 entry[1 ^ afirst] = (png_byte)alpha;
1973 case 1:
1974 entry[afirst] = (png_byte)green;
1975 break;
1976
1977 default:
1978 break;
1979 }
1980 }
1981
1982 # ifdef afirst
1983 # undef afirst
1984 # endif
1985 # ifdef bgr
1986 # undef bgr
1987 # endif
1988 }
1989 }
1990
1991 static int
1992 make_gray_file_colormap(png_image_read_control *display)
1993 {
1994 unsigned int i;
1995
1996 for (i=0; i<256; ++i)
1997 png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
1998
1999 return (int)i;
2000 }
2001
2002 static int
2003 make_gray_colormap(png_image_read_control *display)
2004 {
2005 unsigned int i;
2006
2007 for (i=0; i<256; ++i)
2008 png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2009
2010 return (int)i;
2011 }
2012 #define PNG_GRAY_COLORMAP_ENTRIES 256
2013
2014 static int
2015 make_ga_colormap(png_image_read_control *display)
2016 {
2017 unsigned int i, a;
2018
2019 /* Alpha is retained, the output will be a color-map with entries
2020 * selected by six levels of alpha. One transparent entry, 6 gray
2021 * levels for all the intermediate alpha values, leaving 230 entries
2022 * for the opaque grays. The color-map entries are the six values
2023 * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2024 * relevant entry.
2025 *
2026 * if (alpha > 229) // opaque
2027 * {
2028 * // The 231 entries are selected to make the math below work:
2029 * base = 0;
2030 * entry = (231 * gray + 128) >> 8;
2031 * }
2032 * else if (alpha < 26) // transparent
2033 * {
2034 * base = 231;
2035 * entry = 0;
2036 * }
2037 * else // partially opaque
2038 * {
2039 * base = 226 + 6 * PNG_DIV51(alpha);
2040 * entry = PNG_DIV51(gray);
2041 * }
2042 */
2043 i = 0;
2044 while (i < 231)
2045 {
2046 unsigned int gray = (i * 256 + 115) / 231;
2047 png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2048 }
2049
2050 /* 255 is used here for the component values for consistency with the code
2051 * that undoes premultiplication in pngwrite.c.
2052 */
2053 png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2054
2055 for (a=1; a<5; ++a)
2056 {
2057 unsigned int g;
2058
2059 for (g=0; g<6; ++g)
2060 png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2061 P_sRGB);
2062 }
2063
2064 return (int)i;
2065 }
2066
2067 #define PNG_GA_COLORMAP_ENTRIES 256
2068
2069 static int
2070 make_rgb_colormap(png_image_read_control *display)
2071 {
2072 unsigned int i, r;
2073
2074 /* Build a 6x6x6 opaque RGB cube */
2075 for (i=r=0; r<6; ++r)
2076 {
2077 unsigned int g;
2078
2079 for (g=0; g<6; ++g)
2080 {
2081 unsigned int b;
2082
2083 for (b=0; b<6; ++b)
2084 png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2085 P_sRGB);
2086 }
2087 }
2088
2089 return (int)i;
2090 }
2091
2092 #define PNG_RGB_COLORMAP_ENTRIES 216
2093
2094 /* Return a palette index to the above palette given three 8-bit sRGB values. */
2095 #define PNG_RGB_INDEX(r,g,b) \
2096 ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2097
2098 static int
2099 png_image_read_colormap(png_voidp argument)
2100 {
2101 png_image_read_control *display =
2102 png_voidcast(png_image_read_control*, argument);
2103 const png_imagep image = display->image;
2104
2105 const png_structrp png_ptr = image->opaque->png_ptr;
2106 const png_uint_32 output_format = image->format;
2107 const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2108 P_LINEAR : P_sRGB;
2109
2110 unsigned int cmap_entries;
2111 unsigned int output_processing; /* Output processing option */
2112 unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2113
2114 /* Background information; the background color and the index of this color
2115 * in the color-map if it exists (else 256).
2116 */
2117 unsigned int background_index = 256;
2118 png_uint_32 back_r, back_g, back_b;
2119
2120 /* Flags to accumulate things that need to be done to the input. */
2121 int expand_tRNS = 0;
2122
2123 /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2124 * very difficult to do, the results look awful, and it is difficult to see
2125 * what possible use it is because the application can't control the
2126 * color-map.
2127 */
2128 if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2129 png_ptr->num_trans > 0) /* alpha in input */ &&
2130 ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2131 {
2132 if (output_encoding == P_LINEAR) /* compose on black */
2133 back_b = back_g = back_r = 0;
2134
2135 else if (display->background == NULL /* no way to remove it */)
2136 png_error(png_ptr,
2137 "background color must be supplied to remove alpha/transparency");
2138
2139 /* Get a copy of the background color (this avoids repeating the checks
2140 * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2141 * output format.
2142 */
2143 else
2144 {
2145 back_g = display->background->green;
2146 if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2147 {
2148 back_r = display->background->red;
2149 back_b = display->background->blue;
2150 }
2151 else
2152 back_b = back_r = back_g;
2153 }
2154 }
2155
2156 else if (output_encoding == P_LINEAR)
2157 back_b = back_r = back_g = 65535;
2158
2159 else
2160 back_b = back_r = back_g = 255;
2161
2162 /* Default the input file gamma if required - this is necessary because
2163 * libpng assumes that if no gamma information is present the data is in the
2164 * output format, but the simplified API deduces the gamma from the input
2165 * format.
2166 */
2167 if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2168 {
2169 /* Do this directly, not using the png_colorspace functions, to ensure
2170 * that it happens even if the colorspace is invalid (though probably if
2171 * it is the setting will be ignored) Note that the same thing can be
2172 * achieved at the application interface with png_set_gAMA.
2173 */
2174 if (png_ptr->bit_depth == 16 &&
2175 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2176 png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2177
2178 else
2179 png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2180
2181 png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2182 }
2183
2184 /* Decide what to do based on the PNG color type of the input data. The
2185 * utility function png_create_colormap_entry deals with most aspects of the
2186 * output transformations; this code works out how to produce bytes of
2187 * color-map entries from the original format.
2188 */
2189 switch (png_ptr->color_type)
2190 {
2191 case PNG_COLOR_TYPE_GRAY:
2192 if (png_ptr->bit_depth <= 8)
2193 {
2194 /* There at most 256 colors in the output, regardless of
2195 * transparency.
2196 */
2197 unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2198
2199 cmap_entries = 1U << png_ptr->bit_depth;
2200 if (cmap_entries > image->colormap_entries)
2201 png_error(png_ptr, "gray[8] color-map: too few entries");
2202
2203 step = 255 / (cmap_entries - 1);
2204 output_processing = PNG_CMAP_NONE;
2205
2206 /* If there is a tRNS chunk then this either selects a transparent
2207 * value or, if the output has no alpha, the background color.
2208 */
2209 if (png_ptr->num_trans > 0)
2210 {
2211 trans = png_ptr->trans_color.gray;
2212
2213 if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2214 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2215 }
2216
2217 /* png_create_colormap_entry just takes an RGBA and writes the
2218 * corresponding color-map entry using the format from 'image',
2219 * including the required conversion to sRGB or linear as
2220 * appropriate. The input values are always either sRGB (if the
2221 * gamma correction flag is 0) or 0..255 scaled file encoded values
2222 * (if the function must gamma correct them).
2223 */
2224 for (i=val=0; i<cmap_entries; ++i, val += step)
2225 {
2226 /* 'i' is a file value. While this will result in duplicated
2227 * entries for 8-bit non-sRGB encoded files it is necessary to
2228 * have non-gamma corrected values to do tRNS handling.
2229 */
2230 if (i != trans)
2231 png_create_colormap_entry(display, i, val, val, val, 255,
2232 P_FILE/*8-bit with file gamma*/);
2233
2234 /* Else this entry is transparent. The colors don't matter if
2235 * there is an alpha channel (back_alpha == 0), but it does no
2236 * harm to pass them in; the values are not set above so this
2237 * passes in white.
2238 *
2239 * NOTE: this preserves the full precision of the application
2240 * supplied background color when it is used.
2241 */
2242 else
2243 png_create_colormap_entry(display, i, back_r, back_g, back_b,
2244 back_alpha, output_encoding);
2245 }
2246
2247 /* We need libpng to preserve the original encoding. */
2248 data_encoding = P_FILE;
2249
2250 /* The rows from libpng, while technically gray values, are now also
2251 * color-map indices; however, they may need to be expanded to 1
2252 * byte per pixel. This is what png_set_packing does (i.e., it
2253 * unpacks the bit values into bytes.)
2254 */
2255 if (png_ptr->bit_depth < 8)
2256 png_set_packing(png_ptr);
2257 }
2258
2259 else /* bit depth is 16 */
2260 {
2261 /* The 16-bit input values can be converted directly to 8-bit gamma
2262 * encoded values; however, if a tRNS chunk is present 257 color-map
2263 * entries are required. This means that the extra entry requires
2264 * special processing; add an alpha channel, sacrifice gray level
2265 * 254 and convert transparent (alpha==0) entries to that.
2266 *
2267 * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2268 * same time to minimize quality loss. If a tRNS chunk is present
2269 * this means libpng must handle it too; otherwise it is impossible
2270 * to do the exact match on the 16-bit value.
2271 *
2272 * If the output has no alpha channel *and* the background color is
2273 * gray then it is possible to let libpng handle the substitution by
2274 * ensuring that the corresponding gray level matches the background
2275 * color exactly.
2276 */
2277 data_encoding = P_sRGB;
2278
2279 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2280 png_error(png_ptr, "gray[16] color-map: too few entries");
2281
2282 cmap_entries = (unsigned int)make_gray_colormap(display);
2283
2284 if (png_ptr->num_trans > 0)
2285 {
2286 unsigned int back_alpha;
2287
2288 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2289 back_alpha = 0;
2290
2291 else
2292 {
2293 if (back_r == back_g && back_g == back_b)
2294 {
2295 /* Background is gray; no special processing will be
2296 * required.
2297 */
2298 png_color_16 c;
2299 png_uint_32 gray = back_g;
2300
2301 if (output_encoding == P_LINEAR)
2302 {
2303 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2304
2305 /* And make sure the corresponding palette entry
2306 * matches.
2307 */
2308 png_create_colormap_entry(display, gray, back_g, back_g,
2309 back_g, 65535, P_LINEAR);
2310 }
2311
2312 /* The background passed to libpng, however, must be the
2313 * sRGB value.
2314 */
2315 c.index = 0; /*unused*/
2316 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2317
2318 /* NOTE: does this work without expanding tRNS to alpha?
2319 * It should be the color->gray case below apparently
2320 * doesn't.
2321 */
2322 png_set_background_fixed(png_ptr, &c,
2323 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2324 0/*gamma: not used*/);
2325
2326 output_processing = PNG_CMAP_NONE;
2327 break;
2328 }
2329 #ifdef __COVERITY__
2330 /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2331 * here.
2332 */
2333 back_alpha = 255;
2334 #else
2335 back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2336 #endif
2337 }
2338
2339 /* output_processing means that the libpng-processed row will be
2340 * 8-bit GA and it has to be processing to single byte color-map
2341 * values. Entry 254 is replaced by either a completely
2342 * transparent entry or by the background color at full
2343 * precision (and the background color is not a simple gray
2344 * level in this case.)
2345 */
2346 expand_tRNS = 1;
2347 output_processing = PNG_CMAP_TRANS;
2348 background_index = 254;
2349
2350 /* And set (overwrite) color-map entry 254 to the actual
2351 * background color at full precision.
2352 */
2353 png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2354 back_alpha, output_encoding);
2355 }
2356
2357 else
2358 output_processing = PNG_CMAP_NONE;
2359 }
2360 break;
2361
2362 case PNG_COLOR_TYPE_GRAY_ALPHA:
2363 /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2364 * of 65536 combinations. If, however, the alpha channel is to be
2365 * removed there are only 256 possibilities if the background is gray.
2366 * (Otherwise there is a subset of the 65536 possibilities defined by
2367 * the triangle between black, white and the background color.)
2368 *
2369 * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2370 * worry about tRNS matching - tRNS is ignored if there is an alpha
2371 * channel.
2372 */
2373 data_encoding = P_sRGB;
2374
2375 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2376 {
2377 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2378 png_error(png_ptr, "gray+alpha color-map: too few entries");
2379
2380 cmap_entries = (unsigned int)make_ga_colormap(display);
2381
2382 background_index = PNG_CMAP_GA_BACKGROUND;
2383 output_processing = PNG_CMAP_GA;
2384 }
2385
2386 else /* alpha is removed */
2387 {
2388 /* Alpha must be removed as the PNG data is processed when the
2389 * background is a color because the G and A channels are
2390 * independent and the vector addition (non-parallel vectors) is a
2391 * 2-D problem.
2392 *
2393 * This can be reduced to the same algorithm as above by making a
2394 * colormap containing gray levels (for the opaque grays), a
2395 * background entry (for a transparent pixel) and a set of four six
2396 * level color values, one set for each intermediate alpha value.
2397 * See the comments in make_ga_colormap for how this works in the
2398 * per-pixel processing.
2399 *
2400 * If the background is gray, however, we only need a 256 entry gray
2401 * level color map. It is sufficient to make the entry generated
2402 * for the background color be exactly the color specified.
2403 */
2404 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2405 (back_r == back_g && back_g == back_b))
2406 {
2407 /* Background is gray; no special processing will be required. */
2408 png_color_16 c;
2409 png_uint_32 gray = back_g;
2410
2411 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2412 png_error(png_ptr, "gray-alpha color-map: too few entries");
2413
2414 cmap_entries = (unsigned int)make_gray_colormap(display);
2415
2416 if (output_encoding == P_LINEAR)
2417 {
2418 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2419
2420 /* And make sure the corresponding palette entry matches. */
2421 png_create_colormap_entry(display, gray, back_g, back_g,
2422 back_g, 65535, P_LINEAR);
2423 }
2424
2425 /* The background passed to libpng, however, must be the sRGB
2426 * value.
2427 */
2428 c.index = 0; /*unused*/
2429 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2430
2431 png_set_background_fixed(png_ptr, &c,
2432 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2433 0/*gamma: not used*/);
2434
2435 output_processing = PNG_CMAP_NONE;
2436 }
2437
2438 else
2439 {
2440 png_uint_32 i, a;
2441
2442 /* This is the same as png_make_ga_colormap, above, except that
2443 * the entries are all opaque.
2444 */
2445 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2446 png_error(png_ptr, "ga-alpha color-map: too few entries");
2447
2448 i = 0;
2449 while (i < 231)
2450 {
2451 png_uint_32 gray = (i * 256 + 115) / 231;
2452 png_create_colormap_entry(display, i++, gray, gray, gray,
2453 255, P_sRGB);
2454 }
2455
2456 /* NOTE: this preserves the full precision of the application
2457 * background color.
2458 */
2459 background_index = i;
2460 png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2461 #ifdef __COVERITY__
2462 /* Coverity claims that output_encoding
2463 * cannot be 2 (P_LINEAR) here.
2464 */ 255U,
2465 #else
2466 output_encoding == P_LINEAR ? 65535U : 255U,
2467 #endif
2468 output_encoding);
2469
2470 /* For non-opaque input composite on the sRGB background - this
2471 * requires inverting the encoding for each component. The input
2472 * is still converted to the sRGB encoding because this is a
2473 * reasonable approximate to the logarithmic curve of human
2474 * visual sensitivity, at least over the narrow range which PNG
2475 * represents. Consequently 'G' is always sRGB encoded, while
2476 * 'A' is linear. We need the linear background colors.
2477 */
2478 if (output_encoding == P_sRGB) /* else already linear */
2479 {
2480 /* This may produce a value not exactly matching the
2481 * background, but that's ok because these numbers are only
2482 * used when alpha != 0
2483 */
2484 back_r = png_sRGB_table[back_r];
2485 back_g = png_sRGB_table[back_g];
2486 back_b = png_sRGB_table[back_b];
2487 }
2488
2489 for (a=1; a<5; ++a)
2490 {
2491 unsigned int g;
2492
2493 /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2494 * by an 8-bit alpha value (0..255).
2495 */
2496 png_uint_32 alpha = 51 * a;
2497 png_uint_32 back_rx = (255-alpha) * back_r;
2498 png_uint_32 back_gx = (255-alpha) * back_g;
2499 png_uint_32 back_bx = (255-alpha) * back_b;
2500
2501 for (g=0; g<6; ++g)
2502 {
2503 png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2504
2505 png_create_colormap_entry(display, i++,
2506 PNG_sRGB_FROM_LINEAR(gray + back_rx),
2507 PNG_sRGB_FROM_LINEAR(gray + back_gx),
2508 PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2509 }
2510 }
2511
2512 cmap_entries = i;
2513 output_processing = PNG_CMAP_GA;
2514 }
2515 }
2516 break;
2517
2518 case PNG_COLOR_TYPE_RGB:
2519 case PNG_COLOR_TYPE_RGB_ALPHA:
2520 /* Exclude the case where the output is gray; we can always handle this
2521 * with the cases above.
2522 */
2523 if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2524 {
2525 /* The color-map will be grayscale, so we may as well convert the
2526 * input RGB values to a simple grayscale and use the grayscale
2527 * code above.
2528 *
2529 * NOTE: calling this apparently damages the recognition of the
2530 * transparent color in background color handling; call
2531 * png_set_tRNS_to_alpha before png_set_background_fixed.
2532 */
2533 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2534 -1);
2535 data_encoding = P_sRGB;
2536
2537 /* The output will now be one or two 8-bit gray or gray+alpha
2538 * channels. The more complex case arises when the input has alpha.
2539 */
2540 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2541 png_ptr->num_trans > 0) &&
2542 (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2543 {
2544 /* Both input and output have an alpha channel, so no background
2545 * processing is required; just map the GA bytes to the right
2546 * color-map entry.
2547 */
2548 expand_tRNS = 1;
2549
2550 if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2551 png_error(png_ptr, "rgb[ga] color-map: too few entries");
2552
2553 cmap_entries = (unsigned int)make_ga_colormap(display);
2554 background_index = PNG_CMAP_GA_BACKGROUND;
2555 output_processing = PNG_CMAP_GA;
2556 }
2557
2558 else
2559 {
2560 /* Either the input or the output has no alpha channel, so there
2561 * will be no non-opaque pixels in the color-map; it will just be
2562 * grayscale.
2563 */
2564 if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2565 png_error(png_ptr, "rgb[gray] color-map: too few entries");
2566
2567 /* Ideally this code would use libpng to do the gamma correction,
2568 * but if an input alpha channel is to be removed we will hit the
2569 * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2570 * correction bug). Fix this by dropping the gamma correction in
2571 * this case and doing it in the palette; this will result in
2572 * duplicate palette entries, but that's better than the
2573 * alternative of double gamma correction.
2574 */
2575 if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2576 png_ptr->num_trans > 0) &&
2577 png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2578 {
2579 cmap_entries = (unsigned int)make_gray_file_colormap(display);
2580 data_encoding = P_FILE;
2581 }
2582
2583 else
2584 cmap_entries = (unsigned int)make_gray_colormap(display);
2585
2586 /* But if the input has alpha or transparency it must be removed
2587 */
2588 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2589 png_ptr->num_trans > 0)
2590 {
2591 png_color_16 c;
2592 png_uint_32 gray = back_g;
2593
2594 /* We need to ensure that the application background exists in
2595 * the colormap and that completely transparent pixels map to
2596 * it. Achieve this simply by ensuring that the entry
2597 * selected for the background really is the background color.
2598 */
2599 if (data_encoding == P_FILE) /* from the fixup above */
2600 {
2601 /* The app supplied a gray which is in output_encoding, we
2602 * need to convert it to a value of the input (P_FILE)
2603 * encoding then set this palette entry to the required
2604 * output encoding.
2605 */
2606 if (output_encoding == P_sRGB)
2607 gray = png_sRGB_table[gray]; /* now P_LINEAR */
2608
2609 gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2610 png_ptr->colorspace.gamma)); /* now P_FILE */
2611
2612 /* And make sure the corresponding palette entry contains
2613 * exactly the required sRGB value.
2614 */
2615 png_create_colormap_entry(display, gray, back_g, back_g,
2616 back_g, 0/*unused*/, output_encoding);
2617 }
2618
2619 else if (output_encoding == P_LINEAR)
2620 {
2621 gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2622
2623 /* And make sure the corresponding palette entry matches.
2624 */
2625 png_create_colormap_entry(display, gray, back_g, back_g,
2626 back_g, 0/*unused*/, P_LINEAR);
2627 }
2628
2629 /* The background passed to libpng, however, must be the
2630 * output (normally sRGB) value.
2631 */
2632 c.index = 0; /*unused*/
2633 c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2634
2635 /* NOTE: the following is apparently a bug in libpng. Without
2636 * it the transparent color recognition in
2637 * png_set_background_fixed seems to go wrong.
2638 */
2639 expand_tRNS = 1;
2640 png_set_background_fixed(png_ptr, &c,
2641 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2642 0/*gamma: not used*/);
2643 }
2644
2645 output_processing = PNG_CMAP_NONE;
2646 }
2647 }
2648
2649 else /* output is color */
2650 {
2651 /* We could use png_quantize here so long as there is no transparent
2652 * color or alpha; png_quantize ignores alpha. Easier overall just
2653 * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2654 * Consequently we always want libpng to produce sRGB data.
2655 */
2656 data_encoding = P_sRGB;
2657
2658 /* Is there any transparency or alpha? */
2659 if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2660 png_ptr->num_trans > 0)
2661 {
2662 /* Is there alpha in the output too? If so all four channels are
2663 * processed into a special RGB cube with alpha support.
2664 */
2665 if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2666 {
2667 png_uint_32 r;
2668
2669 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2670 png_error(png_ptr, "rgb+alpha color-map: too few entries");
2671
2672 cmap_entries = (unsigned int)make_rgb_colormap(display);
2673
2674 /* Add a transparent entry. */
2675 png_create_colormap_entry(display, cmap_entries, 255, 255,
2676 255, 0, P_sRGB);
2677
2678 /* This is stored as the background index for the processing
2679 * algorithm.
2680 */
2681 background_index = cmap_entries++;
2682
2683 /* Add 27 r,g,b entries each with alpha 0.5. */
2684 for (r=0; r<256; r = (r << 1) | 0x7f)
2685 {
2686 png_uint_32 g;
2687
2688 for (g=0; g<256; g = (g << 1) | 0x7f)
2689 {
2690 png_uint_32 b;
2691
2692 /* This generates components with the values 0, 127 and
2693 * 255
2694 */
2695 for (b=0; b<256; b = (b << 1) | 0x7f)
2696 png_create_colormap_entry(display, cmap_entries++,
2697 r, g, b, 128, P_sRGB);
2698 }
2699 }
2700
2701 expand_tRNS = 1;
2702 output_processing = PNG_CMAP_RGB_ALPHA;
2703 }
2704
2705 else
2706 {
2707 /* Alpha/transparency must be removed. The background must
2708 * exist in the color map (achieved by setting adding it after
2709 * the 666 color-map). If the standard processing code will
2710 * pick up this entry automatically that's all that is
2711 * required; libpng can be called to do the background
2712 * processing.
2713 */
2714 unsigned int sample_size =
2715 PNG_IMAGE_SAMPLE_SIZE(output_format);
2716 png_uint_32 r, g, b; /* sRGB background */
2717
2718 if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2719 png_error(png_ptr, "rgb-alpha color-map: too few entries");
2720
2721 cmap_entries = (unsigned int)make_rgb_colormap(display);
2722
2723 png_create_colormap_entry(display, cmap_entries, back_r,
2724 back_g, back_b, 0/*unused*/, output_encoding);
2725
2726 if (output_encoding == P_LINEAR)
2727 {
2728 r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2729 g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2730 b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2731 }
2732
2733 else
2734 {
2735 r = back_r;
2736 g = back_g;
2737 b = back_g;
2738 }
2739
2740 /* Compare the newly-created color-map entry with the one the
2741 * PNG_CMAP_RGB algorithm will use. If the two entries don't
2742 * match, add the new one and set this as the background
2743 * index.
2744 */
2745 if (memcmp((png_const_bytep)display->colormap +
2746 sample_size * cmap_entries,
2747 (png_const_bytep)display->colormap +
2748 sample_size * PNG_RGB_INDEX(r,g,b),
2749 sample_size) != 0)
2750 {
2751 /* The background color must be added. */
2752 background_index = cmap_entries++;
2753
2754 /* Add 27 r,g,b entries each with created by composing with
2755 * the background at alpha 0.5.
2756 */
2757 for (r=0; r<256; r = (r << 1) | 0x7f)
2758 {
2759 for (g=0; g<256; g = (g << 1) | 0x7f)
2760 {
2761 /* This generates components with the values 0, 127
2762 * and 255
2763 */
2764 for (b=0; b<256; b = (b << 1) | 0x7f)
2765 png_create_colormap_entry(display, cmap_entries++,
2766 png_colormap_compose(display, r, P_sRGB, 128,
2767 back_r, output_encoding),
2768 png_colormap_compose(display, g, P_sRGB, 128,
2769 back_g, output_encoding),
2770 png_colormap_compose(display, b, P_sRGB, 128,
2771 back_b, output_encoding),
2772 0/*unused*/, output_encoding);
2773 }
2774 }
2775
2776 expand_tRNS = 1;
2777 output_processing = PNG_CMAP_RGB_ALPHA;
2778 }
2779
2780 else /* background color is in the standard color-map */
2781 {
2782 png_color_16 c;
2783
2784 c.index = 0; /*unused*/
2785 c.red = (png_uint_16)back_r;
2786 c.gray = c.green = (png_uint_16)back_g;
2787 c.blue = (png_uint_16)back_b;
2788
2789 png_set_background_fixed(png_ptr, &c,
2790 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2791 0/*gamma: not used*/);
2792
2793 output_processing = PNG_CMAP_RGB;
2794 }
2795 }
2796 }
2797
2798 else /* no alpha or transparency in the input */
2799 {
2800 /* Alpha in the output is irrelevant, simply map the opaque input
2801 * pixels to the 6x6x6 color-map.
2802 */
2803 if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2804 png_error(png_ptr, "rgb color-map: too few entries");
2805
2806 cmap_entries = (unsigned int)make_rgb_colormap(display);
2807 output_processing = PNG_CMAP_RGB;
2808 }
2809 }
2810 break;
2811
2812 case PNG_COLOR_TYPE_PALETTE:
2813 /* It's already got a color-map. It may be necessary to eliminate the
2814 * tRNS entries though.
2815 */
2816 {
2817 unsigned int num_trans = png_ptr->num_trans;
2818 png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
2819 png_const_colorp colormap = png_ptr->palette;
2820 const int do_background = trans != NULL &&
2821 (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
2822 unsigned int i;
2823
2824 /* Just in case: */
2825 if (trans == NULL)
2826 num_trans = 0;
2827
2828 output_processing = PNG_CMAP_NONE;
2829 data_encoding = P_FILE; /* Don't change from color-map indices */
2830 cmap_entries = (unsigned int)png_ptr->num_palette;
2831 if (cmap_entries > 256)
2832 cmap_entries = 256;
2833
2834 if (cmap_entries > (unsigned int)image->colormap_entries)
2835 png_error(png_ptr, "palette color-map: too few entries");
2836
2837 for (i=0; i < cmap_entries; ++i)
2838 {
2839 if (do_background != 0 && i < num_trans && trans[i] < 255)
2840 {
2841 if (trans[i] == 0)
2842 png_create_colormap_entry(display, i, back_r, back_g,
2843 back_b, 0, output_encoding);
2844
2845 else
2846 {
2847 /* Must compose the PNG file color in the color-map entry
2848 * on the sRGB color in 'back'.
2849 */
2850 png_create_colormap_entry(display, i,
2851 png_colormap_compose(display, colormap[i].red,
2852 P_FILE, trans[i], back_r, output_encoding),
2853 png_colormap_compose(display, colormap[i].green,
2854 P_FILE, trans[i], back_g, output_encoding),
2855 png_colormap_compose(display, colormap[i].blue,
2856 P_FILE, trans[i], back_b, output_encoding),
2857 output_encoding == P_LINEAR ? trans[i] * 257U :
2858 trans[i],
2859 output_encoding);
2860 }
2861 }
2862
2863 else
2864 png_create_colormap_entry(display, i, colormap[i].red,
2865 colormap[i].green, colormap[i].blue,
2866 i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
2867 }
2868
2869 /* The PNG data may have indices packed in fewer than 8 bits, it
2870 * must be expanded if so.
2871 */
2872 if (png_ptr->bit_depth < 8)
2873 png_set_packing(png_ptr);
2874 }
2875 break;
2876
2877 default:
2878 png_error(png_ptr, "invalid PNG color type");
2879 /*NOT REACHED*/
2880 }
2881
2882 /* Now deal with the output processing */
2883 if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
2884 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
2885 png_set_tRNS_to_alpha(png_ptr);
2886
2887 switch (data_encoding)
2888 {
2889 case P_sRGB:
2890 /* Change to 8-bit sRGB */
2891 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
2892 /* FALL THROUGH */
2893
2894 case P_FILE:
2895 if (png_ptr->bit_depth > 8)
2896 png_set_scale_16(png_ptr);
2897 break;
2898
2899 #ifdef __GNUC__
2900 default:
2901 png_error(png_ptr, "bad data option (internal error)");
2902 #endif
2903 }
2904
2905 if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
2906 png_error(png_ptr, "color map overflow (BAD internal error)");
2907
2908 image->colormap_entries = cmap_entries;
2909
2910 /* Double check using the recorded background index */
2911 switch (output_processing)
2912 {
2913 case PNG_CMAP_NONE:
2914 if (background_index != PNG_CMAP_NONE_BACKGROUND)
2915 goto bad_background;
2916 break;
2917
2918 case PNG_CMAP_GA:
2919 if (background_index != PNG_CMAP_GA_BACKGROUND)
2920 goto bad_background;
2921 break;
2922
2923 case PNG_CMAP_TRANS:
2924 if (background_index >= cmap_entries ||
2925 background_index != PNG_CMAP_TRANS_BACKGROUND)
2926 goto bad_background;
2927 break;
2928
2929 case PNG_CMAP_RGB:
2930 if (background_index != PNG_CMAP_RGB_BACKGROUND)
2931 goto bad_background;
2932 break;
2933
2934 case PNG_CMAP_RGB_ALPHA:
2935 if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
2936 goto bad_background;
2937 break;
2938
2939 default:
2940 png_error(png_ptr, "bad processing option (internal error)");
2941
2942 bad_background:
2943 png_error(png_ptr, "bad background index (internal error)");
2944 }
2945
2946 display->colormap_processing = (int)output_processing;
2947
2948 return 1/*ok*/;
2949 }
2950
2951 /* The final part of the color-map read called from png_image_finish_read. */
2952 static int
2953 png_image_read_and_map(png_voidp argument)
2954 {
2955 png_image_read_control *display = png_voidcast(png_image_read_control*,
2956 argument);
2957 png_imagep image = display->image;
2958 png_structrp png_ptr = image->opaque->png_ptr;
2959 int passes;
2960
2961 /* Called when the libpng data must be transformed into the color-mapped
2962 * form. There is a local row buffer in display->local and this routine must
2963 * do the interlace handling.
2964 */
2965 switch (png_ptr->interlaced)
2966 {
2967 case PNG_INTERLACE_NONE:
2968 passes = 1;
2969 break;
2970
2971 case PNG_INTERLACE_ADAM7:
2972 passes = PNG_INTERLACE_ADAM7_PASSES;
2973 break;
2974
2975 default:
2976 png_error(png_ptr, "unknown interlace type");
2977 }
2978
2979 {
2980 png_uint_32 height = image->height;
2981 png_uint_32 width = image->width;
2982 int proc = display->colormap_processing;
2983 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
2984 ptrdiff_t step_row = display->row_bytes;
2985 int pass;
2986
2987 for (pass = 0; pass < passes; ++pass)
2988 {
2989 unsigned int startx, stepx, stepy;
2990 png_uint_32 y;
2991
2992 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
2993 {
2994 /* The row may be empty for a short image: */
2995 if (PNG_PASS_COLS(width, pass) == 0)
2996 continue;
2997
2998 startx = PNG_PASS_START_COL(pass);
2999 stepx = PNG_PASS_COL_OFFSET(pass);
3000 y = PNG_PASS_START_ROW(pass);
3001 stepy = PNG_PASS_ROW_OFFSET(pass);
3002 }
3003
3004 else
3005 {
3006 y = 0;
3007 startx = 0;
3008 stepx = stepy = 1;
3009 }
3010
3011 for (; y<height; y += stepy)
3012 {
3013 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3014 png_bytep outrow = first_row + y * step_row;
3015 png_const_bytep end_row = outrow + width;
3016
3017 /* Read read the libpng data into the temporary buffer. */
3018 png_read_row(png_ptr, inrow, NULL);
3019
3020 /* Now process the row according to the processing option, note
3021 * that the caller verifies that the format of the libpng output
3022 * data is as required.
3023 */
3024 outrow += startx;
3025 switch (proc)
3026 {
3027 case PNG_CMAP_GA:
3028 for (; outrow < end_row; outrow += stepx)
3029 {
3030 /* The data is always in the PNG order */
3031 unsigned int gray = *inrow++;
3032 unsigned int alpha = *inrow++;
3033 unsigned int entry;
3034
3035 /* NOTE: this code is copied as a comment in
3036 * make_ga_colormap above. Please update the
3037 * comment if you change this code!
3038 */
3039 if (alpha > 229) /* opaque */
3040 {
3041 entry = (231 * gray + 128) >> 8;
3042 }
3043 else if (alpha < 26) /* transparent */
3044 {
3045 entry = 231;
3046 }
3047 else /* partially opaque */
3048 {
3049 entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3050 }
3051
3052 *outrow = (png_byte)entry;
3053 }
3054 break;
3055
3056 case PNG_CMAP_TRANS:
3057 for (; outrow < end_row; outrow += stepx)
3058 {
3059 png_byte gray = *inrow++;
3060 png_byte alpha = *inrow++;
3061
3062 if (alpha == 0)
3063 *outrow = PNG_CMAP_TRANS_BACKGROUND;
3064
3065 else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3066 *outrow = gray;
3067
3068 else
3069 *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3070 }
3071 break;
3072
3073 case PNG_CMAP_RGB:
3074 for (; outrow < end_row; outrow += stepx)
3075 {
3076 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3077 inrow += 3;
3078 }
3079 break;
3080
3081 case PNG_CMAP_RGB_ALPHA:
3082 for (; outrow < end_row; outrow += stepx)
3083 {
3084 unsigned int alpha = inrow[3];
3085
3086 /* Because the alpha entries only hold alpha==0.5 values
3087 * split the processing at alpha==0.25 (64) and 0.75
3088 * (196).
3089 */
3090
3091 if (alpha >= 196)
3092 *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3093 inrow[2]);
3094
3095 else if (alpha < 64)
3096 *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3097
3098 else
3099 {
3100 /* Likewise there are three entries for each of r, g
3101 * and b. We could select the entry by popcount on
3102 * the top two bits on those architectures that
3103 * support it, this is what the code below does,
3104 * crudely.
3105 */
3106 unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3107
3108 /* Here are how the values map:
3109 *
3110 * 0x00 .. 0x3f -> 0
3111 * 0x40 .. 0xbf -> 1
3112 * 0xc0 .. 0xff -> 2
3113 *
3114 * So, as above with the explicit alpha checks, the
3115 * breakpoints are at 64 and 196.
3116 */
3117 if (inrow[0] & 0x80) back_i += 9; /* red */
3118 if (inrow[0] & 0x40) back_i += 9;
3119 if (inrow[0] & 0x80) back_i += 3; /* green */
3120 if (inrow[0] & 0x40) back_i += 3;
3121 if (inrow[0] & 0x80) back_i += 1; /* blue */
3122 if (inrow[0] & 0x40) back_i += 1;
3123
3124 *outrow = (png_byte)back_i;
3125 }
3126
3127 inrow += 4;
3128 }
3129 break;
3130
3131 default:
3132 break;
3133 }
3134 }
3135 }
3136 }
3137
3138 return 1;
3139 }
3140
3141 static int
3142 png_image_read_colormapped(png_voidp argument)
3143 {
3144 png_image_read_control *display = png_voidcast(png_image_read_control*,
3145 argument);
3146 png_imagep image = display->image;
3147 png_controlp control = image->opaque;
3148 png_structrp png_ptr = control->png_ptr;
3149 png_inforp info_ptr = control->info_ptr;
3150
3151 int passes = 0; /* As a flag */
3152
3153 PNG_SKIP_CHUNKS(png_ptr);
3154
3155 /* Update the 'info' structure and make sure the result is as required; first
3156 * make sure to turn on the interlace handling if it will be required
3157 * (because it can't be turned on *after* the call to png_read_update_info!)
3158 */
3159 if (display->colormap_processing == PNG_CMAP_NONE)
3160 passes = png_set_interlace_handling(png_ptr);
3161
3162 png_read_update_info(png_ptr, info_ptr);
3163
3164 /* The expected output can be deduced from the colormap_processing option. */
3165 switch (display->colormap_processing)
3166 {
3167 case PNG_CMAP_NONE:
3168 /* Output must be one channel and one byte per pixel, the output
3169 * encoding can be anything.
3170 */
3171 if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3172 info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3173 info_ptr->bit_depth == 8)
3174 break;
3175
3176 goto bad_output;
3177
3178 case PNG_CMAP_TRANS:
3179 case PNG_CMAP_GA:
3180 /* Output must be two channels and the 'G' one must be sRGB, the latter
3181 * can be checked with an exact number because it should have been set
3182 * to this number above!
3183 */
3184 if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3185 info_ptr->bit_depth == 8 &&
3186 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3187 image->colormap_entries == 256)
3188 break;
3189
3190 goto bad_output;
3191
3192 case PNG_CMAP_RGB:
3193 /* Output must be 8-bit sRGB encoded RGB */
3194 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3195 info_ptr->bit_depth == 8 &&
3196 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3197 image->colormap_entries == 216)
3198 break;
3199
3200 goto bad_output;
3201
3202 case PNG_CMAP_RGB_ALPHA:
3203 /* Output must be 8-bit sRGB encoded RGBA */
3204 if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3205 info_ptr->bit_depth == 8 &&
3206 png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3207 image->colormap_entries == 244 /* 216 + 1 + 27 */)
3208 break;
3209
3210 /* goto bad_output; */
3211 /* FALL THROUGH */
3212
3213 default:
3214 bad_output:
3215 png_error(png_ptr, "bad color-map processing (internal error)");
3216 }
3217
3218 /* Now read the rows. Do this here if it is possible to read directly into
3219 * the output buffer, otherwise allocate a local row buffer of the maximum
3220 * size libpng requires and call the relevant processing routine safely.
3221 */
3222 {
3223 png_voidp first_row = display->buffer;
3224 ptrdiff_t row_bytes = display->row_stride;
3225
3226 /* The following expression is designed to work correctly whether it gives
3227 * a signed or an unsigned result.
3228 */
3229 if (row_bytes < 0)
3230 {
3231 char *ptr = png_voidcast(char*, first_row);
3232 ptr += (image->height-1) * (-row_bytes);
3233 first_row = png_voidcast(png_voidp, ptr);
3234 }
3235
3236 display->first_row = first_row;
3237 display->row_bytes = row_bytes;
3238 }
3239
3240 if (passes == 0)
3241 {
3242 int result;
3243 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3244
3245 display->local_row = row;
3246 result = png_safe_execute(image, png_image_read_and_map, display);
3247 display->local_row = NULL;
3248 png_free(png_ptr, row);
3249
3250 return result;
3251 }
3252
3253 else
3254 {
3255 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
3256
3257 while (--passes >= 0)
3258 {
3259 png_uint_32 y = image->height;
3260 png_bytep row = png_voidcast(png_bytep, display->first_row);
3261
3262 for (; y > 0; --y)
3263 {
3264 png_read_row(png_ptr, row, NULL);
3265 row += row_bytes;
3266 }
3267 }
3268
3269 return 1;
3270 }
3271 }
3272
3273 /* Just the row reading part of png_image_read. */
3274 static int
3275 png_image_read_composite(png_voidp argument)
3276 {
3277 png_image_read_control *display = png_voidcast(png_image_read_control*,
3278 argument);
3279 png_imagep image = display->image;
3280 png_structrp png_ptr = image->opaque->png_ptr;
3281 int passes;
3282
3283 switch (png_ptr->interlaced)
3284 {
3285 case PNG_INTERLACE_NONE:
3286 passes = 1;
3287 break;
3288
3289 case PNG_INTERLACE_ADAM7:
3290 passes = PNG_INTERLACE_ADAM7_PASSES;
3291 break;
3292
3293 default:
3294 png_error(png_ptr, "unknown interlace type");
3295 }
3296
3297 {
3298 png_uint_32 height = image->height;
3299 png_uint_32 width = image->width;
3300 ptrdiff_t step_row = display->row_bytes;
3301 unsigned int channels =
3302 (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3303 int pass;
3304
3305 for (pass = 0; pass < passes; ++pass)
3306 {
3307 unsigned int startx, stepx, stepy;
3308 png_uint_32 y;
3309
3310 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3311 {
3312 /* The row may be empty for a short image: */
3313 if (PNG_PASS_COLS(width, pass) == 0)
3314 continue;
3315
3316 startx = PNG_PASS_START_COL(pass) * channels;
3317 stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3318 y = PNG_PASS_START_ROW(pass);
3319 stepy = PNG_PASS_ROW_OFFSET(pass);
3320 }
3321
3322 else
3323 {
3324 y = 0;
3325 startx = 0;
3326 stepx = channels;
3327 stepy = 1;
3328 }
3329
3330 for (; y<height; y += stepy)
3331 {
3332 png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3333 png_bytep outrow;
3334 png_const_bytep end_row;
3335
3336 /* Read the row, which is packed: */
3337 png_read_row(png_ptr, inrow, NULL);
3338
3339 outrow = png_voidcast(png_bytep, display->first_row);
3340 outrow += y * step_row;
3341 end_row = outrow + width * channels;
3342
3343 /* Now do the composition on each pixel in this row. */
3344 outrow += startx;
3345 for (; outrow < end_row; outrow += stepx)
3346 {
3347 png_byte alpha = inrow[channels];
3348
3349 if (alpha > 0) /* else no change to the output */
3350 {
3351 unsigned int c;
3352
3353 for (c=0; c<channels; ++c)
3354 {
3355 png_uint_32 component = inrow[c];
3356
3357 if (alpha < 255) /* else just use component */
3358 {
3359 /* This is PNG_OPTIMIZED_ALPHA, the component value
3360 * is a linear 8-bit value. Combine this with the
3361 * current outrow[c] value which is sRGB encoded.
3362 * Arithmetic here is 16-bits to preserve the output
3363 * values correctly.
3364 */
3365 component *= 257*255; /* =65535 */
3366 component += (255-alpha)*png_sRGB_table[outrow[c]];
3367
3368 /* So 'component' is scaled by 255*65535 and is
3369 * therefore appropriate for the sRGB to linear
3370 * conversion table.
3371 */
3372 component = PNG_sRGB_FROM_LINEAR(component);
3373 }
3374
3375 outrow[c] = (png_byte)component;
3376 }
3377 }
3378
3379 inrow += channels+1; /* components and alpha channel */
3380 }
3381 }
3382 }
3383 }
3384
3385 return 1;
3386 }
3387
3388 /* The do_local_background case; called when all the following transforms are to
3389 * be done:
3390 *
3391 * PNG_RGB_TO_GRAY
3392 * PNG_COMPOSITE
3393 * PNG_GAMMA
3394 *
3395 * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3396 * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3397 * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3398 * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3399 * row and handles the removal or pre-multiplication of the alpha channel.
3400 */
3401 static int
3402 png_image_read_background(png_voidp argument)
3403 {
3404 png_image_read_control *display = png_voidcast(png_image_read_control*,
3405 argument);
3406 png_imagep image = display->image;
3407 png_structrp png_ptr = image->opaque->png_ptr;
3408 png_inforp info_ptr = image->opaque->info_ptr;
3409 png_uint_32 height = image->height;
3410 png_uint_32 width = image->width;
3411 int pass, passes;
3412
3413 /* Double check the convoluted logic below. We expect to get here with
3414 * libpng doing rgb to gray and gamma correction but background processing
3415 * left to the png_image_read_background function. The rows libpng produce
3416 * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3417 */
3418 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3419 png_error(png_ptr, "lost rgb to gray");
3420
3421 if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3422 png_error(png_ptr, "unexpected compose");
3423
3424 if (png_get_channels(png_ptr, info_ptr) != 2)
3425 png_error(png_ptr, "lost/gained channels");
3426
3427 /* Expect the 8-bit case to always remove the alpha channel */
3428 if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3429 (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3430 png_error(png_ptr, "unexpected 8-bit transformation");
3431
3432 switch (png_ptr->interlaced)
3433 {
3434 case PNG_INTERLACE_NONE:
3435 passes = 1;
3436 break;
3437
3438 case PNG_INTERLACE_ADAM7:
3439 passes = PNG_INTERLACE_ADAM7_PASSES;
3440 break;
3441
3442 default:
3443 png_error(png_ptr, "unknown interlace type");
3444 }
3445
3446 /* Use direct access to info_ptr here because otherwise the simplified API
3447 * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3448 * checking the value after libpng expansions, not the original value in the
3449 * PNG.
3450 */
3451 switch (info_ptr->bit_depth)
3452 {
3453 case 8:
3454 /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3455 * to be removed by composing on a background: either the row if
3456 * display->background is NULL or display->background->green if not.
3457 * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3458 */
3459 {
3460 png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3461 ptrdiff_t step_row = display->row_bytes;
3462
3463 for (pass = 0; pass < passes; ++pass)
3464 {
3465 png_bytep row = png_voidcast(png_bytep, 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 unsigned int preserve_alpha = (image->format &
3591 PNG_FORMAT_FLAG_ALPHA) != 0;
3592 unsigned int outchannels = 1U+preserve_alpha;
3593 int swap_alpha = 0;
3594
3595 # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3596 if (preserve_alpha != 0 &&
3597 (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3598 swap_alpha = 1;
3599 # endif
3600
3601 for (pass = 0; pass < passes; ++pass)
3602 {
3603 unsigned int startx, stepx, stepy;
3604 png_uint_32 y;
3605
3606 /* The 'x' start and step are adjusted to output components here.
3607 */
3608 if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3609 {
3610 /* The row may be empty for a short image: */
3611 if (PNG_PASS_COLS(width, pass) == 0)
3612 continue;
3613
3614 startx = PNG_PASS_START_COL(pass) * outchannels;
3615 stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3616 y = PNG_PASS_START_ROW(pass);
3617 stepy = PNG_PASS_ROW_OFFSET(pass);
3618 }
3619
3620 else
3621 {
3622 y = 0;
3623 startx = 0;
3624 stepx = outchannels;
3625 stepy = 1;
3626 }
3627
3628 for (; y<height; y += stepy)
3629 {
3630 png_const_uint_16p inrow;
3631 png_uint_16p outrow = first_row + y*step_row;
3632 png_uint_16p end_row = outrow + width * outchannels;
3633
3634 /* Read the row, which is packed: */
3635 png_read_row(png_ptr, png_voidcast(png_bytep,
3636 display->local_row), NULL);
3637 inrow = png_voidcast(png_const_uint_16p, display->local_row);
3638
3639 /* Now do the pre-multiplication on each pixel in this row.
3640 */
3641 outrow += startx;
3642 for (; outrow < end_row; outrow += stepx)
3643 {
3644 png_uint_32 component = inrow[0];
3645 png_uint_16 alpha = inrow[1];
3646
3647 if (alpha > 0) /* else 0 */
3648 {
3649 if (alpha < 65535) /* else just use component */
3650 {
3651 component *= alpha;
3652 component += 32767;
3653 component /= 65535;
3654 }
3655 }
3656
3657 else
3658 component = 0;
3659
3660 outrow[swap_alpha] = (png_uint_16)component;
3661 if (preserve_alpha != 0)
3662 outrow[1 ^ swap_alpha] = alpha;
3663
3664 inrow += 2; /* components and alpha channel */
3665 }
3666 }
3667 }
3668 }
3669 break;
3670
3671 #ifdef __GNUC__
3672 default:
3673 png_error(png_ptr, "unexpected bit depth");
3674 #endif
3675 }
3676
3677 return 1;
3678 }
3679
3680 /* The guts of png_image_finish_read as a png_safe_execute callback. */
3681 static int
3682 png_image_read_direct(png_voidp argument)
3683 {
3684 png_image_read_control *display = png_voidcast(png_image_read_control*,
3685 argument);
3686 png_imagep image = display->image;
3687 png_structrp png_ptr = image->opaque->png_ptr;
3688 png_inforp info_ptr = image->opaque->info_ptr;
3689
3690 png_uint_32 format = image->format;
3691 int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3692 int do_local_compose = 0;
3693 int do_local_background = 0; /* to avoid double gamma correction bug */
3694 int passes = 0;
3695
3696 /* Add transforms to ensure the correct output format is produced then check
3697 * that the required implementation support is there. Always expand; always
3698 * need 8 bits minimum, no palette and expanded tRNS.
3699 */
3700 png_set_expand(png_ptr);
3701
3702 /* Now check the format to see if it was modified. */
3703 {
3704 png_uint_32 base_format = png_image_format(png_ptr) &
3705 ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3706 png_uint_32 change = format ^ base_format;
3707 png_fixed_point output_gamma;
3708 int mode; /* alpha mode */
3709
3710 /* Do this first so that we have a record if rgb to gray is happening. */
3711 if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3712 {
3713 /* gray<->color transformation required. */
3714 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3715 png_set_gray_to_rgb(png_ptr);
3716
3717 else
3718 {
3719 /* libpng can't do both rgb to gray and
3720 * background/pre-multiplication if there is also significant gamma
3721 * correction, because both operations require linear colors and
3722 * the code only supports one transform doing the gamma correction.
3723 * Handle this by doing the pre-multiplication or background
3724 * operation in this code, if necessary.
3725 *
3726 * TODO: fix this by rewriting pngrtran.c (!)
3727 *
3728 * For the moment (given that fixing this in pngrtran.c is an
3729 * enormous change) 'do_local_background' is used to indicate that
3730 * the problem exists.
3731 */
3732 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3733 do_local_background = 1/*maybe*/;
3734
3735 png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3736 PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3737 }
3738
3739 change &= ~PNG_FORMAT_FLAG_COLOR;
3740 }
3741
3742 /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3743 */
3744 {
3745 png_fixed_point input_gamma_default;
3746
3747 if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3748 (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3749 input_gamma_default = PNG_GAMMA_LINEAR;
3750 else
3751 input_gamma_default = PNG_DEFAULT_sRGB;
3752
3753 /* Call png_set_alpha_mode to set the default for the input gamma; the
3754 * output gamma is set by a second call below.
3755 */
3756 png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3757 }
3758
3759 if (linear != 0)
3760 {
3761 /* If there *is* an alpha channel in the input it must be multiplied
3762 * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3763 */
3764 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3765 mode = PNG_ALPHA_STANDARD; /* associated alpha */
3766
3767 else
3768 mode = PNG_ALPHA_PNG;
3769
3770 output_gamma = PNG_GAMMA_LINEAR;
3771 }
3772
3773 else
3774 {
3775 mode = PNG_ALPHA_PNG;
3776 output_gamma = PNG_DEFAULT_sRGB;
3777 }
3778
3779 /* If 'do_local_background' is set check for the presence of gamma
3780 * correction; this is part of the work-round for the libpng bug
3781 * described above.
3782 *
3783 * TODO: fix libpng and remove this.
3784 */
3785 if (do_local_background != 0)
3786 {
3787 png_fixed_point gtest;
3788
3789 /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3790 * gamma correction, the screen gamma hasn't been set on png_struct
3791 * yet; it's set below. png_struct::gamma, however, is set to the
3792 * final value.
3793 */
3794 if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
3795 PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3796 do_local_background = 0;
3797
3798 else if (mode == PNG_ALPHA_STANDARD)
3799 {
3800 do_local_background = 2/*required*/;
3801 mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
3802 }
3803
3804 /* else leave as 1 for the checks below */
3805 }
3806
3807 /* If the bit-depth changes then handle that here. */
3808 if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
3809 {
3810 if (linear != 0 /*16-bit output*/)
3811 png_set_expand_16(png_ptr);
3812
3813 else /* 8-bit output */
3814 png_set_scale_16(png_ptr);
3815
3816 change &= ~PNG_FORMAT_FLAG_LINEAR;
3817 }
3818
3819 /* Now the background/alpha channel changes. */
3820 if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
3821 {
3822 /* Removing an alpha channel requires composition for the 8-bit
3823 * formats; for the 16-bit it is already done, above, by the
3824 * pre-multiplication and the channel just needs to be stripped.
3825 */
3826 if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3827 {
3828 /* If RGB->gray is happening the alpha channel must be left and the
3829 * operation completed locally.
3830 *
3831 * TODO: fix libpng and remove this.
3832 */
3833 if (do_local_background != 0)
3834 do_local_background = 2/*required*/;
3835
3836 /* 16-bit output: just remove the channel */
3837 else if (linear != 0) /* compose on black (well, pre-multiply) */
3838 png_set_strip_alpha(png_ptr);
3839
3840 /* 8-bit output: do an appropriate compose */
3841 else if (display->background != NULL)
3842 {
3843 png_color_16 c;
3844
3845 c.index = 0; /*unused*/
3846 c.red = display->background->red;
3847 c.green = display->background->green;
3848 c.blue = display->background->blue;
3849 c.gray = display->background->green;
3850
3851 /* This is always an 8-bit sRGB value, using the 'green' channel
3852 * for gray is much better than calculating the luminance here;
3853 * we can get off-by-one errors in that calculation relative to
3854 * the app expectations and that will show up in transparent
3855 * pixels.
3856 */
3857 png_set_background_fixed(png_ptr, &c,
3858 PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3859 0/*gamma: not used*/);
3860 }
3861
3862 else /* compose on row: implemented below. */
3863 {
3864 do_local_compose = 1;
3865 /* This leaves the alpha channel in the output, so it has to be
3866 * removed by the code below. Set the encoding to the 'OPTIMIZE'
3867 * one so the code only has to hack on the pixels that require
3868 * composition.
3869 */
3870 mode = PNG_ALPHA_OPTIMIZED;
3871 }
3872 }
3873
3874 else /* output needs an alpha channel */
3875 {
3876 /* This is tricky because it happens before the swap operation has
3877 * been accomplished; however, the swap does *not* swap the added
3878 * alpha channel (weird API), so it must be added in the correct
3879 * place.
3880 */
3881 png_uint_32 filler; /* opaque filler */
3882 int where;
3883
3884 if (linear != 0)
3885 filler = 65535;
3886
3887 else
3888 filler = 255;
3889
3890 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
3891 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3892 {
3893 where = PNG_FILLER_BEFORE;
3894 change &= ~PNG_FORMAT_FLAG_AFIRST;
3895 }
3896
3897 else
3898 #endif
3899 where = PNG_FILLER_AFTER;
3900
3901 png_set_add_alpha(png_ptr, filler, where);
3902 }
3903
3904 /* This stops the (irrelevant) call to swap_alpha below. */
3905 change &= ~PNG_FORMAT_FLAG_ALPHA;
3906 }
3907
3908 /* Now set the alpha mode correctly; this is always done, even if there is
3909 * no alpha channel in either the input or the output because it correctly
3910 * sets the output gamma.
3911 */
3912 png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
3913
3914 # ifdef PNG_FORMAT_BGR_SUPPORTED
3915 if ((change & PNG_FORMAT_FLAG_BGR) != 0)
3916 {
3917 /* Check only the output format; PNG is never BGR; don't do this if
3918 * the output is gray, but fix up the 'format' value in that case.
3919 */
3920 if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3921 png_set_bgr(png_ptr);
3922
3923 else
3924 format &= ~PNG_FORMAT_FLAG_BGR;
3925
3926 change &= ~PNG_FORMAT_FLAG_BGR;
3927 }
3928 # endif
3929
3930 # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3931 if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
3932 {
3933 /* Only relevant if there is an alpha channel - it's particularly
3934 * important to handle this correctly because do_local_compose may
3935 * be set above and then libpng will keep the alpha channel for this
3936 * code to remove.
3937 */
3938 if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
3939 {
3940 /* Disable this if doing a local background,
3941 * TODO: remove this when local background is no longer required.
3942 */
3943 if (do_local_background != 2)
3944 png_set_swap_alpha(png_ptr);
3945 }
3946
3947 else
3948 format &= ~PNG_FORMAT_FLAG_AFIRST;
3949
3950 change &= ~PNG_FORMAT_FLAG_AFIRST;
3951 }
3952 # endif
3953
3954 /* If the *output* is 16-bit then we need to check for a byte-swap on this
3955 * architecture.
3956 */
3957 if (linear != 0)
3958 {
3959 PNG_CONST png_uint_16 le = 0x0001;
3960
3961 if ((*(png_const_bytep) & le) != 0)
3962 png_set_swap(png_ptr);
3963 }
3964
3965 /* If change is not now 0 some transformation is missing - error out. */
3966 if (change != 0)
3967 png_error(png_ptr, "png_read_image: unsupported transformation");
3968 }
3969
3970 PNG_SKIP_CHUNKS(png_ptr);
3971
3972 /* Update the 'info' structure and make sure the result is as required; first
3973 * make sure to turn on the interlace handling if it will be required
3974 * (because it can't be turned on *after* the call to png_read_update_info!)
3975 *
3976 * TODO: remove the do_local_background fixup below.
3977 */
3978 if (do_local_compose == 0 && do_local_background != 2)
3979 passes = png_set_interlace_handling(png_ptr);
3980
3981 png_read_update_info(png_ptr, info_ptr);
3982
3983 {
3984 png_uint_32 info_format = 0;
3985
3986 if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
3987 info_format |= PNG_FORMAT_FLAG_COLOR;
3988
3989 if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
3990 {
3991 /* do_local_compose removes this channel below. */
3992 if (do_local_compose == 0)
3993 {
3994 /* do_local_background does the same if required. */
3995 if (do_local_background != 2 ||
3996 (format & PNG_FORMAT_FLAG_ALPHA) != 0)
3997 info_format |= PNG_FORMAT_FLAG_ALPHA;
3998 }
3999 }
4000
4001 else if (do_local_compose != 0) /* internal error */
4002 png_error(png_ptr, "png_image_read: alpha channel lost");
4003
4004 if (info_ptr->bit_depth == 16)
4005 info_format |= PNG_FORMAT_FLAG_LINEAR;
4006
4007 #ifdef PNG_FORMAT_BGR_SUPPORTED
4008 if ((png_ptr->transformations & PNG_BGR) != 0)
4009 info_format |= PNG_FORMAT_FLAG_BGR;
4010 #endif
4011
4012 #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4013 if (do_local_background == 2)
4014 {
4015 if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4016 info_format |= PNG_FORMAT_FLAG_AFIRST;
4017 }
4018
4019 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4020 ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4021 (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4022 {
4023 if (do_local_background == 2)
4024 png_error(png_ptr, "unexpected alpha swap transformation");
4025
4026 info_format |= PNG_FORMAT_FLAG_AFIRST;
4027 }
4028 # endif
4029
4030 /* This is actually an internal error. */
4031 if (info_format != format)
4032 png_error(png_ptr, "png_read_image: invalid transformations");
4033 }
4034
4035 /* Now read the rows. If do_local_compose is set then it is necessary to use
4036 * a local row buffer. The output will be GA, RGBA or BGRA and must be
4037 * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
4038 * display acts as a flag.
4039 */
4040 {
4041 png_voidp first_row = display->buffer;
4042 ptrdiff_t row_bytes = display->row_stride;
4043
4044 if (linear != 0)
4045 row_bytes *= 2;
4046
4047 /* The following expression is designed to work correctly whether it gives
4048 * a signed or an unsigned result.
4049 */
4050 if (row_bytes < 0)
4051 {
4052 char *ptr = png_voidcast(char*, first_row);
4053 ptr += (image->height-1) * (-row_bytes);
4054 first_row = png_voidcast(png_voidp, ptr);
4055 }
4056
4057 display->first_row = first_row;
4058 display->row_bytes = row_bytes;
4059 }
4060
4061 if (do_local_compose != 0)
4062 {
4063 int result;
4064 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4065
4066 display->local_row = row;
4067 result = png_safe_execute(image, png_image_read_composite, display);
4068 display->local_row = NULL;
4069 png_free(png_ptr, row);
4070
4071 return result;
4072 }
4073
4074 else if (do_local_background == 2)
4075 {
4076 int result;
4077 png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4078
4079 display->local_row = row;
4080 result = png_safe_execute(image, png_image_read_background, display);
4081 display->local_row = NULL;
4082 png_free(png_ptr, row);
4083
4084 return result;
4085 }
4086
4087 else
4088 {
4089 png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
4090
4091 while (--passes >= 0)
4092 {
4093 png_uint_32 y = image->height;
4094 png_bytep row = png_voidcast(png_bytep, display->first_row);
4095
4096 for (; y > 0; --y)
4097 {
4098 png_read_row(png_ptr, row, NULL);
4099 row += row_bytes;
4100 }
4101 }
4102
4103 return 1;
4104 }
4105 }
4106
4107 int PNGAPI
4108 png_image_finish_read(png_imagep image, png_const_colorp background,
4109 void *buffer, png_int_32 row_stride, void *colormap)
4110 {
4111 if (image != NULL && image->version == PNG_IMAGE_VERSION)
4112 {
4113 /* Check for row_stride overflow. This check is not performed on the
4114 * original PNG format because it may not occur in the output PNG format
4115 * and libpng deals with the issues of reading the original.
4116 */
4117 const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4118
4119 /* The following checks just the 'row_stride' calculation to ensure it
4120 * fits in a signed 32-bit value. Because channels/components can be
4121 * either 1 or 2 bytes in size the length of a row can still overflow 32
4122 * bits; this is just to verify that the 'row_stride' argument can be
4123 * represented.
4124 */
4125 if (image->width <= 0x7fffffffU/channels) /* no overflow */
4126 {
4127 png_uint_32 check;
4128 const png_uint_32 png_row_stride = image->width * channels;
4129
4130 if (row_stride == 0)
4131 row_stride = (png_int_32)/*SAFE*/png_row_stride;
4132
4133 if (row_stride < 0)
4134 check = (png_uint_32)(-row_stride);
4135
4136 else
4137 check = (png_uint_32)row_stride;
4138
4139 /* This verifies 'check', the absolute value of the actual stride
4140 * passed in and detects overflow in the application calculation (i.e.
4141 * if the app did actually pass in a non-zero 'row_stride'.
4142 */
4143 if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4144 {
4145 /* Now check for overflow of the image buffer calculation; this
4146 * limits the whole image size to 32 bits for API compatibility with
4147 * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4148 *
4149 * The PNG_IMAGE_BUFFER_SIZE macro is:
4150 *
4151 * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
4152 *
4153 * And the component size is always 1 or 2, so make sure that the
4154 * number of *bytes* that the application is saying are available
4155 * does actually fit into a 32-bit number.
4156 *
4157 * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
4158 * will be changed to use png_alloc_size_t; bigger images can be
4159 * accomodated on 64-bit systems.
4160 */
4161 if (image->height <=
4162 0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
4163 {
4164 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4165 (image->colormap_entries > 0 && colormap != NULL))
4166 {
4167 int result;
4168 png_image_read_control display;
4169
4170 memset(&display, 0, (sizeof display));
4171 display.image = image;
4172 display.buffer = buffer;
4173 display.row_stride = row_stride;
4174 display.colormap = colormap;
4175 display.background = background;
4176 display.local_row = NULL;
4177
4178 /* Choose the correct 'end' routine; for the color-map case
4179 * all the setup has already been done.
4180 */
4181 if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4182 result =
4183 png_safe_execute(image,
4184 png_image_read_colormap, &display) &&
4185 png_safe_execute(image,
4186 png_image_read_colormapped, &display);
4187
4188 else
4189 result =
4190 png_safe_execute(image,
4191 png_image_read_direct, &display);
4192
4193 png_image_free(image);
4194 return result;
4195 }
4196
4197 else
4198 return png_image_error(image,
4199 "png_image_finish_read[color-map]: no color-map");
4200 }
4201
4202 else
4203 return png_image_error(image,
4204 "png_image_finish_read: image too large");
4205 }
4206
4207 else
4208 return png_image_error(image,
4209 "png_image_finish_read: invalid argument");
4210 }
4211
4212 else
4213 return png_image_error(image,
4214 "png_image_finish_read: row_stride too large");
4215 }
4216
4217 else if (image != NULL)
4218 return png_image_error(image,
4219 "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4220
4221 return 0;
4222 }
4223
4224 #endif /* SIMPLIFIED_READ */
4225 #endif /* READ */