Line data Source code
1 :
2 : /* pngread.c - read a PNG file
3 : *
4 : * Last changed in libpng 1.6.26 [October 20, 2016]
5 : * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
6 : * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 : * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8 : *
9 : * This code is released under the libpng license.
10 : * For conditions of distribution and use, see the disclaimer
11 : * and license in png.h
12 : *
13 : * This file contains routines that an application calls directly to
14 : * read a PNG file or stream.
15 : */
16 :
17 : #include "pngpriv.h"
18 : #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && defined(PNG_STDIO_SUPPORTED)
19 : # include <errno.h>
20 : #endif
21 :
22 : #ifdef PNG_READ_SUPPORTED
23 :
24 : /* Create a PNG structure for reading, and allocate any memory needed. */
25 31 : PNG_FUNCTION(png_structp,PNGAPI
26 : png_create_read_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
27 : png_error_ptr error_fn, png_error_ptr warn_fn),PNG_ALLOCATED)
28 : {
29 : #ifndef PNG_USER_MEM_SUPPORTED
30 31 : png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
31 : error_fn, warn_fn, NULL, NULL, NULL);
32 : #else
33 : return png_create_read_struct_2(user_png_ver, error_ptr, error_fn,
34 : warn_fn, NULL, NULL, NULL);
35 : }
36 :
37 : /* Alternate create PNG structure for reading, and allocate any memory
38 : * needed.
39 : */
40 : PNG_FUNCTION(png_structp,PNGAPI
41 : png_create_read_struct_2,(png_const_charp user_png_ver, png_voidp error_ptr,
42 : png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
43 : png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
44 : {
45 : png_structp png_ptr = png_create_png_struct(user_png_ver, error_ptr,
46 : error_fn, warn_fn, mem_ptr, malloc_fn, free_fn);
47 : #endif /* USER_MEM */
48 :
49 31 : if (png_ptr != NULL)
50 : {
51 31 : png_ptr->mode = PNG_IS_READ_STRUCT;
52 :
53 : /* Added in libpng-1.6.0; this can be used to detect a read structure if
54 : * required (it will be zero in a write structure.)
55 : */
56 : # ifdef PNG_SEQUENTIAL_READ_SUPPORTED
57 : png_ptr->IDAT_read_size = PNG_IDAT_READ_SIZE;
58 : # endif
59 :
60 : # ifdef PNG_BENIGN_READ_ERRORS_SUPPORTED
61 31 : png_ptr->flags |= PNG_FLAG_BENIGN_ERRORS_WARN;
62 :
63 : /* In stable builds only warn if an application error can be completely
64 : * handled.
65 : */
66 : # if PNG_RELEASE_BUILD
67 31 : png_ptr->flags |= PNG_FLAG_APP_WARNINGS_WARN;
68 : # endif
69 : # endif
70 :
71 : /* TODO: delay this, it can be done in png_init_io (if the app doesn't
72 : * do it itself) avoiding setting the default function if it is not
73 : * required.
74 : */
75 31 : png_set_read_fn(png_ptr, NULL, NULL);
76 : }
77 :
78 31 : return png_ptr;
79 : }
80 :
81 :
82 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
83 : /* Read the information before the actual image data. This has been
84 : * changed in v0.90 to allow reading a file that already has the magic
85 : * bytes read from the stream. You can tell libpng how many bytes have
86 : * been read from the beginning of the stream (up to the maximum of 8)
87 : * via png_set_sig_bytes(), and we will only check the remaining bytes
88 : * here. The application can then have access to the signature bytes we
89 : * read if it is determined that this isn't a valid PNG file.
90 : */
91 : void PNGAPI
92 : png_read_info(png_structrp png_ptr, png_inforp info_ptr)
93 : {
94 : #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
95 : int keep;
96 : #endif
97 :
98 : png_debug(1, "in png_read_info");
99 :
100 : if (png_ptr == NULL || info_ptr == NULL)
101 : return;
102 :
103 : /* Read and check the PNG file signature. */
104 : png_read_sig(png_ptr, info_ptr);
105 :
106 : for (;;)
107 : {
108 : png_uint_32 length = png_read_chunk_header(png_ptr);
109 : png_uint_32 chunk_name = png_ptr->chunk_name;
110 :
111 : /* IDAT logic needs to happen here to simplify getting the two flags
112 : * right.
113 : */
114 : if (chunk_name == png_IDAT)
115 : {
116 : if ((png_ptr->mode & PNG_HAVE_IHDR) == 0)
117 : png_chunk_error(png_ptr, "Missing IHDR before IDAT");
118 :
119 : else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
120 : (png_ptr->mode & PNG_HAVE_PLTE) == 0)
121 : png_chunk_error(png_ptr, "Missing PLTE before IDAT");
122 :
123 : else if ((png_ptr->mode & PNG_AFTER_IDAT) != 0)
124 : png_chunk_benign_error(png_ptr, "Too many IDATs found");
125 :
126 : png_ptr->mode |= PNG_HAVE_IDAT;
127 : }
128 :
129 : else if ((png_ptr->mode & PNG_HAVE_IDAT) != 0)
130 : {
131 : png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
132 : png_ptr->mode |= PNG_AFTER_IDAT;
133 : }
134 :
135 : /* This should be a binary subdivision search or a hash for
136 : * matching the chunk name rather than a linear search.
137 : */
138 : if (chunk_name == png_IHDR)
139 : png_handle_IHDR(png_ptr, info_ptr, length);
140 :
141 : else if (chunk_name == png_IEND)
142 : png_handle_IEND(png_ptr, info_ptr, length);
143 :
144 : #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
145 : else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
146 : {
147 : png_handle_unknown(png_ptr, info_ptr, length, keep);
148 :
149 : if (chunk_name == png_PLTE)
150 : png_ptr->mode |= PNG_HAVE_PLTE;
151 :
152 : else if (chunk_name == png_IDAT)
153 : {
154 : png_ptr->idat_size = 0; /* It has been consumed */
155 : break;
156 : }
157 : }
158 : #endif
159 : else if (chunk_name == png_PLTE)
160 : png_handle_PLTE(png_ptr, info_ptr, length);
161 :
162 : else if (chunk_name == png_IDAT)
163 : {
164 : #ifdef PNG_READ_APNG_SUPPORTED
165 : png_have_info(png_ptr, info_ptr);
166 : #endif
167 : png_ptr->idat_size = length;
168 : break;
169 : }
170 :
171 : #ifdef PNG_READ_bKGD_SUPPORTED
172 : else if (chunk_name == png_bKGD)
173 : png_handle_bKGD(png_ptr, info_ptr, length);
174 : #endif
175 :
176 : #ifdef PNG_READ_cHRM_SUPPORTED
177 : else if (chunk_name == png_cHRM)
178 : png_handle_cHRM(png_ptr, info_ptr, length);
179 : #endif
180 :
181 : #ifdef PNG_READ_gAMA_SUPPORTED
182 : else if (chunk_name == png_gAMA)
183 : png_handle_gAMA(png_ptr, info_ptr, length);
184 : #endif
185 :
186 : #ifdef PNG_READ_hIST_SUPPORTED
187 : else if (chunk_name == png_hIST)
188 : png_handle_hIST(png_ptr, info_ptr, length);
189 : #endif
190 :
191 : #ifdef PNG_READ_oFFs_SUPPORTED
192 : else if (chunk_name == png_oFFs)
193 : png_handle_oFFs(png_ptr, info_ptr, length);
194 : #endif
195 :
196 : #ifdef PNG_READ_pCAL_SUPPORTED
197 : else if (chunk_name == png_pCAL)
198 : png_handle_pCAL(png_ptr, info_ptr, length);
199 : #endif
200 :
201 : #ifdef PNG_READ_sCAL_SUPPORTED
202 : else if (chunk_name == png_sCAL)
203 : png_handle_sCAL(png_ptr, info_ptr, length);
204 : #endif
205 :
206 : #ifdef PNG_READ_pHYs_SUPPORTED
207 : else if (chunk_name == png_pHYs)
208 : png_handle_pHYs(png_ptr, info_ptr, length);
209 : #endif
210 :
211 : #ifdef PNG_READ_sBIT_SUPPORTED
212 : else if (chunk_name == png_sBIT)
213 : png_handle_sBIT(png_ptr, info_ptr, length);
214 : #endif
215 :
216 : #ifdef PNG_READ_sRGB_SUPPORTED
217 : else if (chunk_name == png_sRGB)
218 : png_handle_sRGB(png_ptr, info_ptr, length);
219 : #endif
220 :
221 : #ifdef PNG_READ_iCCP_SUPPORTED
222 : else if (chunk_name == png_iCCP)
223 : png_handle_iCCP(png_ptr, info_ptr, length);
224 : #endif
225 :
226 : #ifdef PNG_READ_sPLT_SUPPORTED
227 : else if (chunk_name == png_sPLT)
228 : png_handle_sPLT(png_ptr, info_ptr, length);
229 : #endif
230 :
231 : #ifdef PNG_READ_tEXt_SUPPORTED
232 : else if (chunk_name == png_tEXt)
233 : png_handle_tEXt(png_ptr, info_ptr, length);
234 : #endif
235 :
236 : #ifdef PNG_READ_tIME_SUPPORTED
237 : else if (chunk_name == png_tIME)
238 : png_handle_tIME(png_ptr, info_ptr, length);
239 : #endif
240 :
241 : #ifdef PNG_READ_tRNS_SUPPORTED
242 : else if (chunk_name == png_tRNS)
243 : png_handle_tRNS(png_ptr, info_ptr, length);
244 : #endif
245 :
246 : #ifdef PNG_READ_zTXt_SUPPORTED
247 : else if (chunk_name == png_zTXt)
248 : png_handle_zTXt(png_ptr, info_ptr, length);
249 : #endif
250 :
251 : #ifdef PNG_READ_iTXt_SUPPORTED
252 : else if (chunk_name == png_iTXt)
253 : png_handle_iTXt(png_ptr, info_ptr, length);
254 : #endif
255 :
256 : #ifdef PNG_READ_APNG_SUPPORTED
257 : else if (chunk_name == png_acTL)
258 : png_handle_acTL(png_ptr, info_ptr, length);
259 :
260 : else if (chunk_name == png_fcTL)
261 : png_handle_fcTL(png_ptr, info_ptr, length);
262 :
263 : else if (chunk_name == png_fdAT)
264 : png_handle_fdAT(png_ptr, info_ptr, length);
265 : #endif
266 :
267 : else
268 : png_handle_unknown(png_ptr, info_ptr, length,
269 : PNG_HANDLE_CHUNK_AS_DEFAULT);
270 : }
271 : }
272 : #endif /* SEQUENTIAL_READ */
273 :
274 : #ifdef PNG_READ_APNG_SUPPORTED
275 : void PNGAPI
276 0 : png_read_frame_head(png_structp png_ptr, png_infop info_ptr)
277 : {
278 : png_byte have_chunk_after_DAT; /* after IDAT or after fdAT */
279 :
280 : png_debug(0, "Reading frame head");
281 :
282 0 : if ((png_ptr->mode & PNG_HAVE_acTL) == 0)
283 0 : png_error(png_ptr, "attempt to png_read_frame_head() but "
284 : "no acTL present");
285 :
286 : /* do nothing for the main IDAT */
287 0 : if (png_ptr->num_frames_read == 0)
288 0 : return;
289 :
290 0 : png_read_reset(png_ptr);
291 0 : png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
292 0 : png_ptr->mode &= ~PNG_HAVE_fcTL;
293 :
294 0 : have_chunk_after_DAT = 0;
295 : for (;;)
296 0 : {
297 0 : png_uint_32 length = png_read_chunk_header(png_ptr);
298 :
299 0 : if (png_ptr->chunk_name == png_IDAT)
300 : {
301 : /* discard trailing IDATs for the first frame */
302 0 : if (have_chunk_after_DAT != 0 || png_ptr->num_frames_read > 1)
303 0 : png_error(png_ptr, "png_read_frame_head(): out of place IDAT");
304 0 : png_crc_finish(png_ptr, length);
305 : }
306 :
307 0 : else if (png_ptr->chunk_name == png_fcTL)
308 : {
309 0 : png_handle_fcTL(png_ptr, info_ptr, length);
310 0 : have_chunk_after_DAT = 1;
311 : }
312 :
313 0 : else if (png_ptr->chunk_name == png_fdAT)
314 : {
315 0 : png_ensure_sequence_number(png_ptr, length);
316 :
317 : /* discard trailing fdATs for frames other than the first */
318 0 : if (have_chunk_after_DAT == 0 && png_ptr->num_frames_read > 1)
319 0 : png_crc_finish(png_ptr, length - 4);
320 0 : else if (png_ptr->mode & PNG_HAVE_fcTL)
321 : {
322 0 : png_ptr->idat_size = length - 4;
323 0 : png_ptr->mode |= PNG_HAVE_IDAT;
324 :
325 0 : break;
326 : }
327 : else
328 0 : png_error(png_ptr, "png_read_frame_head(): out of place fdAT");
329 : }
330 : else
331 : {
332 0 : png_warning(png_ptr, "Skipped (ignored) a chunk "
333 : "between APNG chunks");
334 0 : png_crc_finish(png_ptr, length);
335 : }
336 : }
337 : }
338 : #endif /* READ_APNG */
339 :
340 : /* Optional call to update the users info_ptr structure */
341 : void PNGAPI
342 31 : png_read_update_info(png_structrp png_ptr, png_inforp info_ptr)
343 : {
344 : png_debug(1, "in png_read_update_info");
345 :
346 31 : if (png_ptr != NULL)
347 : {
348 31 : if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
349 : {
350 31 : png_read_start_row(png_ptr);
351 :
352 : # ifdef PNG_READ_TRANSFORMS_SUPPORTED
353 31 : png_read_transform_info(png_ptr, info_ptr);
354 : # else
355 : PNG_UNUSED(info_ptr)
356 : # endif
357 : }
358 :
359 : /* New in 1.6.0 this avoids the bug of doing the initializations twice */
360 : else
361 0 : png_app_error(png_ptr,
362 : "png_read_update_info/png_start_read_image: duplicate call");
363 : }
364 31 : }
365 :
366 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
367 : /* Initialize palette, background, etc, after transformations
368 : * are set, but before any reading takes place. This allows
369 : * the user to obtain a gamma-corrected palette, for example.
370 : * If the user doesn't call this, we will do it ourselves.
371 : */
372 : void PNGAPI
373 : png_start_read_image(png_structrp png_ptr)
374 : {
375 : png_debug(1, "in png_start_read_image");
376 :
377 : if (png_ptr != NULL)
378 : {
379 : if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
380 : png_read_start_row(png_ptr);
381 :
382 : /* New in 1.6.0 this avoids the bug of doing the initializations twice */
383 : else
384 : png_app_error(png_ptr,
385 : "png_start_read_image/png_read_update_info: duplicate call");
386 : }
387 : }
388 : #endif /* SEQUENTIAL_READ */
389 :
390 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
391 : #ifdef PNG_MNG_FEATURES_SUPPORTED
392 : /* Undoes intrapixel differencing,
393 : * NOTE: this is apparently only supported in the 'sequential' reader.
394 : */
395 : static void
396 : png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
397 : {
398 : png_debug(1, "in png_do_read_intrapixel");
399 :
400 : if (
401 : (row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
402 : {
403 : int bytes_per_pixel;
404 : png_uint_32 row_width = row_info->width;
405 :
406 : if (row_info->bit_depth == 8)
407 : {
408 : png_bytep rp;
409 : png_uint_32 i;
410 :
411 : if (row_info->color_type == PNG_COLOR_TYPE_RGB)
412 : bytes_per_pixel = 3;
413 :
414 : else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
415 : bytes_per_pixel = 4;
416 :
417 : else
418 : return;
419 :
420 : for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
421 : {
422 : *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
423 : *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
424 : }
425 : }
426 : else if (row_info->bit_depth == 16)
427 : {
428 : png_bytep rp;
429 : png_uint_32 i;
430 :
431 : if (row_info->color_type == PNG_COLOR_TYPE_RGB)
432 : bytes_per_pixel = 6;
433 :
434 : else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
435 : bytes_per_pixel = 8;
436 :
437 : else
438 : return;
439 :
440 : for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
441 : {
442 : png_uint_32 s0 = (png_uint_32)(*(rp ) << 8) | *(rp + 1);
443 : png_uint_32 s1 = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
444 : png_uint_32 s2 = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
445 : png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
446 : png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
447 : *(rp ) = (png_byte)((red >> 8) & 0xff);
448 : *(rp + 1) = (png_byte)(red & 0xff);
449 : *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
450 : *(rp + 5) = (png_byte)(blue & 0xff);
451 : }
452 : }
453 : }
454 : }
455 : #endif /* MNG_FEATURES */
456 :
457 : void PNGAPI
458 : png_read_row(png_structrp png_ptr, png_bytep row, png_bytep dsp_row)
459 : {
460 : png_row_info row_info;
461 :
462 : if (png_ptr == NULL)
463 : return;
464 :
465 : png_debug2(1, "in png_read_row (row %lu, pass %d)",
466 : (unsigned long)png_ptr->row_number, png_ptr->pass);
467 :
468 : /* png_read_start_row sets the information (in particular iwidth) for this
469 : * interlace pass.
470 : */
471 : if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
472 : png_read_start_row(png_ptr);
473 :
474 : /* 1.5.6: row_info moved out of png_struct to a local here. */
475 : row_info.width = png_ptr->iwidth; /* NOTE: width of current interlaced row */
476 : row_info.color_type = png_ptr->color_type;
477 : row_info.bit_depth = png_ptr->bit_depth;
478 : row_info.channels = png_ptr->channels;
479 : row_info.pixel_depth = png_ptr->pixel_depth;
480 : row_info.rowbytes = PNG_ROWBYTES(row_info.pixel_depth, row_info.width);
481 :
482 : #ifdef PNG_WARNINGS_SUPPORTED
483 : if (png_ptr->row_number == 0 && png_ptr->pass == 0)
484 : {
485 : /* Check for transforms that have been set but were defined out */
486 : #if defined(PNG_WRITE_INVERT_SUPPORTED) && !defined(PNG_READ_INVERT_SUPPORTED)
487 : if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
488 : png_warning(png_ptr, "PNG_READ_INVERT_SUPPORTED is not defined");
489 : #endif
490 :
491 : #if defined(PNG_WRITE_FILLER_SUPPORTED) && !defined(PNG_READ_FILLER_SUPPORTED)
492 : if ((png_ptr->transformations & PNG_FILLER) != 0)
493 : png_warning(png_ptr, "PNG_READ_FILLER_SUPPORTED is not defined");
494 : #endif
495 :
496 : #if defined(PNG_WRITE_PACKSWAP_SUPPORTED) && \
497 : !defined(PNG_READ_PACKSWAP_SUPPORTED)
498 : if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
499 : png_warning(png_ptr, "PNG_READ_PACKSWAP_SUPPORTED is not defined");
500 : #endif
501 :
502 : #if defined(PNG_WRITE_PACK_SUPPORTED) && !defined(PNG_READ_PACK_SUPPORTED)
503 : if ((png_ptr->transformations & PNG_PACK) != 0)
504 : png_warning(png_ptr, "PNG_READ_PACK_SUPPORTED is not defined");
505 : #endif
506 :
507 : #if defined(PNG_WRITE_SHIFT_SUPPORTED) && !defined(PNG_READ_SHIFT_SUPPORTED)
508 : if ((png_ptr->transformations & PNG_SHIFT) != 0)
509 : png_warning(png_ptr, "PNG_READ_SHIFT_SUPPORTED is not defined");
510 : #endif
511 :
512 : #if defined(PNG_WRITE_BGR_SUPPORTED) && !defined(PNG_READ_BGR_SUPPORTED)
513 : if ((png_ptr->transformations & PNG_BGR) != 0)
514 : png_warning(png_ptr, "PNG_READ_BGR_SUPPORTED is not defined");
515 : #endif
516 :
517 : #if defined(PNG_WRITE_SWAP_SUPPORTED) && !defined(PNG_READ_SWAP_SUPPORTED)
518 : if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
519 : png_warning(png_ptr, "PNG_READ_SWAP_SUPPORTED is not defined");
520 : #endif
521 : }
522 : #endif /* WARNINGS */
523 :
524 : #ifdef PNG_READ_INTERLACING_SUPPORTED
525 : /* If interlaced and we do not need a new row, combine row and return.
526 : * Notice that the pixels we have from previous rows have been transformed
527 : * already; we can only combine like with like (transformed or
528 : * untransformed) and, because of the libpng API for interlaced images, this
529 : * means we must transform before de-interlacing.
530 : */
531 : if (png_ptr->interlaced != 0 &&
532 : (png_ptr->transformations & PNG_INTERLACE) != 0)
533 : {
534 : switch (png_ptr->pass)
535 : {
536 : case 0:
537 : if (png_ptr->row_number & 0x07)
538 : {
539 : if (dsp_row != NULL)
540 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
541 : png_read_finish_row(png_ptr);
542 : return;
543 : }
544 : break;
545 :
546 : case 1:
547 : if ((png_ptr->row_number & 0x07) || png_ptr->width < 5)
548 : {
549 : if (dsp_row != NULL)
550 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
551 :
552 : png_read_finish_row(png_ptr);
553 : return;
554 : }
555 : break;
556 :
557 : case 2:
558 : if ((png_ptr->row_number & 0x07) != 4)
559 : {
560 : if (dsp_row != NULL && (png_ptr->row_number & 4))
561 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
562 :
563 : png_read_finish_row(png_ptr);
564 : return;
565 : }
566 : break;
567 :
568 : case 3:
569 : if ((png_ptr->row_number & 3) || png_ptr->width < 3)
570 : {
571 : if (dsp_row != NULL)
572 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
573 :
574 : png_read_finish_row(png_ptr);
575 : return;
576 : }
577 : break;
578 :
579 : case 4:
580 : if ((png_ptr->row_number & 3) != 2)
581 : {
582 : if (dsp_row != NULL && (png_ptr->row_number & 2))
583 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
584 :
585 : png_read_finish_row(png_ptr);
586 : return;
587 : }
588 : break;
589 :
590 : case 5:
591 : if ((png_ptr->row_number & 1) || png_ptr->width < 2)
592 : {
593 : if (dsp_row != NULL)
594 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
595 :
596 : png_read_finish_row(png_ptr);
597 : return;
598 : }
599 : break;
600 :
601 : default:
602 : case 6:
603 : if ((png_ptr->row_number & 1) == 0)
604 : {
605 : png_read_finish_row(png_ptr);
606 : return;
607 : }
608 : break;
609 : }
610 : }
611 : #endif
612 :
613 : if ((png_ptr->mode & PNG_HAVE_IDAT) == 0)
614 : png_error(png_ptr, "Invalid attempt to read row data");
615 :
616 : /* Fill the row with IDAT data: */
617 : png_read_IDAT_data(png_ptr, png_ptr->row_buf, row_info.rowbytes + 1);
618 :
619 : if (png_ptr->row_buf[0] > PNG_FILTER_VALUE_NONE)
620 : {
621 : if (png_ptr->row_buf[0] < PNG_FILTER_VALUE_LAST)
622 : png_read_filter_row(png_ptr, &row_info, png_ptr->row_buf + 1,
623 : png_ptr->prev_row + 1, png_ptr->row_buf[0]);
624 : else
625 : png_error(png_ptr, "bad adaptive filter value");
626 : }
627 :
628 : /* libpng 1.5.6: the following line was copying png_ptr->rowbytes before
629 : * 1.5.6, while the buffer really is this big in current versions of libpng
630 : * it may not be in the future, so this was changed just to copy the
631 : * interlaced count:
632 : */
633 : memcpy(png_ptr->prev_row, png_ptr->row_buf, row_info.rowbytes + 1);
634 :
635 : #ifdef PNG_MNG_FEATURES_SUPPORTED
636 : if ((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
637 : (png_ptr->filter_type == PNG_INTRAPIXEL_DIFFERENCING))
638 : {
639 : /* Intrapixel differencing */
640 : png_do_read_intrapixel(&row_info, png_ptr->row_buf + 1);
641 : }
642 : #endif
643 :
644 : #ifdef PNG_READ_TRANSFORMS_SUPPORTED
645 : if (png_ptr->transformations)
646 : png_do_read_transformations(png_ptr, &row_info);
647 : #endif
648 :
649 : /* The transformed pixel depth should match the depth now in row_info. */
650 : if (png_ptr->transformed_pixel_depth == 0)
651 : {
652 : png_ptr->transformed_pixel_depth = row_info.pixel_depth;
653 : if (row_info.pixel_depth > png_ptr->maximum_pixel_depth)
654 : png_error(png_ptr, "sequential row overflow");
655 : }
656 :
657 : else if (png_ptr->transformed_pixel_depth != row_info.pixel_depth)
658 : png_error(png_ptr, "internal sequential row size calculation error");
659 :
660 : #ifdef PNG_READ_INTERLACING_SUPPORTED
661 : /* Expand interlaced rows to full size */
662 : if (png_ptr->interlaced != 0 &&
663 : (png_ptr->transformations & PNG_INTERLACE) != 0)
664 : {
665 : if (png_ptr->pass < 6)
666 : png_do_read_interlace(&row_info, png_ptr->row_buf + 1, png_ptr->pass,
667 : png_ptr->transformations);
668 :
669 : if (dsp_row != NULL)
670 : png_combine_row(png_ptr, dsp_row, 1/*display*/);
671 :
672 : if (row != NULL)
673 : png_combine_row(png_ptr, row, 0/*row*/);
674 : }
675 :
676 : else
677 : #endif
678 : {
679 : if (row != NULL)
680 : png_combine_row(png_ptr, row, -1/*ignored*/);
681 :
682 : if (dsp_row != NULL)
683 : png_combine_row(png_ptr, dsp_row, -1/*ignored*/);
684 : }
685 : png_read_finish_row(png_ptr);
686 :
687 : if (png_ptr->read_row_fn != NULL)
688 : (*(png_ptr->read_row_fn))(png_ptr, png_ptr->row_number, png_ptr->pass);
689 :
690 : }
691 : #endif /* SEQUENTIAL_READ */
692 :
693 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
694 : /* Read one or more rows of image data. If the image is interlaced,
695 : * and png_set_interlace_handling() has been called, the rows need to
696 : * contain the contents of the rows from the previous pass. If the
697 : * image has alpha or transparency, and png_handle_alpha()[*] has been
698 : * called, the rows contents must be initialized to the contents of the
699 : * screen.
700 : *
701 : * "row" holds the actual image, and pixels are placed in it
702 : * as they arrive. If the image is displayed after each pass, it will
703 : * appear to "sparkle" in. "display_row" can be used to display a
704 : * "chunky" progressive image, with finer detail added as it becomes
705 : * available. If you do not want this "chunky" display, you may pass
706 : * NULL for display_row. If you do not want the sparkle display, and
707 : * you have not called png_handle_alpha(), you may pass NULL for rows.
708 : * If you have called png_handle_alpha(), and the image has either an
709 : * alpha channel or a transparency chunk, you must provide a buffer for
710 : * rows. In this case, you do not have to provide a display_row buffer
711 : * also, but you may. If the image is not interlaced, or if you have
712 : * not called png_set_interlace_handling(), the display_row buffer will
713 : * be ignored, so pass NULL to it.
714 : *
715 : * [*] png_handle_alpha() does not exist yet, as of this version of libpng
716 : */
717 :
718 : void PNGAPI
719 : png_read_rows(png_structrp png_ptr, png_bytepp row,
720 : png_bytepp display_row, png_uint_32 num_rows)
721 : {
722 : png_uint_32 i;
723 : png_bytepp rp;
724 : png_bytepp dp;
725 :
726 : png_debug(1, "in png_read_rows");
727 :
728 : if (png_ptr == NULL)
729 : return;
730 :
731 : rp = row;
732 : dp = display_row;
733 : if (rp != NULL && dp != NULL)
734 : for (i = 0; i < num_rows; i++)
735 : {
736 : png_bytep rptr = *rp++;
737 : png_bytep dptr = *dp++;
738 :
739 : png_read_row(png_ptr, rptr, dptr);
740 : }
741 :
742 : else if (rp != NULL)
743 : for (i = 0; i < num_rows; i++)
744 : {
745 : png_bytep rptr = *rp;
746 : png_read_row(png_ptr, rptr, NULL);
747 : rp++;
748 : }
749 :
750 : else if (dp != NULL)
751 : for (i = 0; i < num_rows; i++)
752 : {
753 : png_bytep dptr = *dp;
754 : png_read_row(png_ptr, NULL, dptr);
755 : dp++;
756 : }
757 : }
758 : #endif /* SEQUENTIAL_READ */
759 :
760 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
761 : /* Read the entire image. If the image has an alpha channel or a tRNS
762 : * chunk, and you have called png_handle_alpha()[*], you will need to
763 : * initialize the image to the current image that PNG will be overlaying.
764 : * We set the num_rows again here, in case it was incorrectly set in
765 : * png_read_start_row() by a call to png_read_update_info() or
766 : * png_start_read_image() if png_set_interlace_handling() wasn't called
767 : * prior to either of these functions like it should have been. You can
768 : * only call this function once. If you desire to have an image for
769 : * each pass of a interlaced image, use png_read_rows() instead.
770 : *
771 : * [*] png_handle_alpha() does not exist yet, as of this version of libpng
772 : */
773 : void PNGAPI
774 : png_read_image(png_structrp png_ptr, png_bytepp image)
775 : {
776 : png_uint_32 i, image_height;
777 : int pass, j;
778 : png_bytepp rp;
779 :
780 : png_debug(1, "in png_read_image");
781 :
782 : if (png_ptr == NULL)
783 : return;
784 :
785 : #ifdef PNG_READ_INTERLACING_SUPPORTED
786 : if ((png_ptr->flags & PNG_FLAG_ROW_INIT) == 0)
787 : {
788 : pass = png_set_interlace_handling(png_ptr);
789 : /* And make sure transforms are initialized. */
790 : png_start_read_image(png_ptr);
791 : }
792 : else
793 : {
794 : if (png_ptr->interlaced != 0 &&
795 : (png_ptr->transformations & PNG_INTERLACE) == 0)
796 : {
797 : /* Caller called png_start_read_image or png_read_update_info without
798 : * first turning on the PNG_INTERLACE transform. We can fix this here,
799 : * but the caller should do it!
800 : */
801 : png_warning(png_ptr, "Interlace handling should be turned on when "
802 : "using png_read_image");
803 : /* Make sure this is set correctly */
804 : png_ptr->num_rows = png_ptr->height;
805 : }
806 :
807 : /* Obtain the pass number, which also turns on the PNG_INTERLACE flag in
808 : * the above error case.
809 : */
810 : pass = png_set_interlace_handling(png_ptr);
811 : }
812 : #else
813 : if (png_ptr->interlaced)
814 : png_error(png_ptr,
815 : "Cannot read interlaced image -- interlace handler disabled");
816 :
817 : pass = 1;
818 : #endif
819 :
820 : image_height=png_ptr->height;
821 :
822 : for (j = 0; j < pass; j++)
823 : {
824 : rp = image;
825 : for (i = 0; i < image_height; i++)
826 : {
827 : png_read_row(png_ptr, *rp, NULL);
828 : rp++;
829 : }
830 : }
831 : }
832 : #endif /* SEQUENTIAL_READ */
833 :
834 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
835 : /* Read the end of the PNG file. Will not read past the end of the
836 : * file, will verify the end is accurate, and will read any comments
837 : * or time information at the end of the file, if info is not NULL.
838 : */
839 : void PNGAPI
840 : png_read_end(png_structrp png_ptr, png_inforp info_ptr)
841 : {
842 : #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
843 : int keep;
844 : #endif
845 :
846 : png_debug(1, "in png_read_end");
847 :
848 : if (png_ptr == NULL)
849 : return;
850 :
851 : /* If png_read_end is called in the middle of reading the rows there may
852 : * still be pending IDAT data and an owned zstream. Deal with this here.
853 : */
854 : #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
855 : if (png_chunk_unknown_handling(png_ptr, png_IDAT) == 0)
856 : #endif
857 : png_read_finish_IDAT(png_ptr);
858 :
859 : #ifdef PNG_READ_CHECK_FOR_INVALID_INDEX_SUPPORTED
860 : /* Report invalid palette index; added at libng-1.5.10 */
861 : if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
862 : png_ptr->num_palette_max > png_ptr->num_palette)
863 : png_benign_error(png_ptr, "Read palette index exceeding num_palette");
864 : #endif
865 :
866 : do
867 : {
868 : png_uint_32 length = png_read_chunk_header(png_ptr);
869 : png_uint_32 chunk_name = png_ptr->chunk_name;
870 :
871 : if (chunk_name != png_IDAT)
872 : png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;
873 :
874 : if (chunk_name == png_IEND)
875 : png_handle_IEND(png_ptr, info_ptr, length);
876 :
877 : else if (chunk_name == png_IHDR)
878 : png_handle_IHDR(png_ptr, info_ptr, length);
879 :
880 : else if (info_ptr == NULL)
881 : png_crc_finish(png_ptr, length);
882 :
883 : #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
884 : else if ((keep = png_chunk_unknown_handling(png_ptr, chunk_name)) != 0)
885 : {
886 : if (chunk_name == png_IDAT)
887 : {
888 : if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
889 : || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
890 : png_benign_error(png_ptr, ".Too many IDATs found");
891 : }
892 : png_handle_unknown(png_ptr, info_ptr, length, keep);
893 : if (chunk_name == png_PLTE)
894 : png_ptr->mode |= PNG_HAVE_PLTE;
895 : }
896 : #endif
897 :
898 : else if (chunk_name == png_IDAT)
899 : {
900 : /* Zero length IDATs are legal after the last IDAT has been
901 : * read, but not after other chunks have been read. 1.6 does not
902 : * always read all the deflate data; specifically it cannot be relied
903 : * upon to read the Adler32 at the end. If it doesn't ignore IDAT
904 : * chunks which are longer than zero as well:
905 : */
906 : if ((length > 0 && !(png_ptr->flags & PNG_FLAG_ZSTREAM_ENDED))
907 : || (png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT) != 0)
908 : png_benign_error(png_ptr, "..Too many IDATs found");
909 :
910 : png_crc_finish(png_ptr, length);
911 : }
912 : else if (chunk_name == png_PLTE)
913 : png_handle_PLTE(png_ptr, info_ptr, length);
914 :
915 : #ifdef PNG_READ_bKGD_SUPPORTED
916 : else if (chunk_name == png_bKGD)
917 : png_handle_bKGD(png_ptr, info_ptr, length);
918 : #endif
919 :
920 : #ifdef PNG_READ_cHRM_SUPPORTED
921 : else if (chunk_name == png_cHRM)
922 : png_handle_cHRM(png_ptr, info_ptr, length);
923 : #endif
924 :
925 : #ifdef PNG_READ_gAMA_SUPPORTED
926 : else if (chunk_name == png_gAMA)
927 : png_handle_gAMA(png_ptr, info_ptr, length);
928 : #endif
929 :
930 : #ifdef PNG_READ_hIST_SUPPORTED
931 : else if (chunk_name == png_hIST)
932 : png_handle_hIST(png_ptr, info_ptr, length);
933 : #endif
934 :
935 : #ifdef PNG_READ_oFFs_SUPPORTED
936 : else if (chunk_name == png_oFFs)
937 : png_handle_oFFs(png_ptr, info_ptr, length);
938 : #endif
939 :
940 : #ifdef PNG_READ_pCAL_SUPPORTED
941 : else if (chunk_name == png_pCAL)
942 : png_handle_pCAL(png_ptr, info_ptr, length);
943 : #endif
944 :
945 : #ifdef PNG_READ_sCAL_SUPPORTED
946 : else if (chunk_name == png_sCAL)
947 : png_handle_sCAL(png_ptr, info_ptr, length);
948 : #endif
949 :
950 : #ifdef PNG_READ_pHYs_SUPPORTED
951 : else if (chunk_name == png_pHYs)
952 : png_handle_pHYs(png_ptr, info_ptr, length);
953 : #endif
954 :
955 : #ifdef PNG_READ_sBIT_SUPPORTED
956 : else if (chunk_name == png_sBIT)
957 : png_handle_sBIT(png_ptr, info_ptr, length);
958 : #endif
959 :
960 : #ifdef PNG_READ_sRGB_SUPPORTED
961 : else if (chunk_name == png_sRGB)
962 : png_handle_sRGB(png_ptr, info_ptr, length);
963 : #endif
964 :
965 : #ifdef PNG_READ_iCCP_SUPPORTED
966 : else if (chunk_name == png_iCCP)
967 : png_handle_iCCP(png_ptr, info_ptr, length);
968 : #endif
969 :
970 : #ifdef PNG_READ_sPLT_SUPPORTED
971 : else if (chunk_name == png_sPLT)
972 : png_handle_sPLT(png_ptr, info_ptr, length);
973 : #endif
974 :
975 : #ifdef PNG_READ_tEXt_SUPPORTED
976 : else if (chunk_name == png_tEXt)
977 : png_handle_tEXt(png_ptr, info_ptr, length);
978 : #endif
979 :
980 : #ifdef PNG_READ_tIME_SUPPORTED
981 : else if (chunk_name == png_tIME)
982 : png_handle_tIME(png_ptr, info_ptr, length);
983 : #endif
984 :
985 : #ifdef PNG_READ_tRNS_SUPPORTED
986 : else if (chunk_name == png_tRNS)
987 : png_handle_tRNS(png_ptr, info_ptr, length);
988 : #endif
989 :
990 : #ifdef PNG_READ_zTXt_SUPPORTED
991 : else if (chunk_name == png_zTXt)
992 : png_handle_zTXt(png_ptr, info_ptr, length);
993 : #endif
994 :
995 : #ifdef PNG_READ_iTXt_SUPPORTED
996 : else if (chunk_name == png_iTXt)
997 : png_handle_iTXt(png_ptr, info_ptr, length);
998 : #endif
999 :
1000 : else
1001 : png_handle_unknown(png_ptr, info_ptr, length,
1002 : PNG_HANDLE_CHUNK_AS_DEFAULT);
1003 : } while ((png_ptr->mode & PNG_HAVE_IEND) == 0);
1004 : }
1005 : #endif /* SEQUENTIAL_READ */
1006 :
1007 : /* Free all memory used in the read struct */
1008 : static void
1009 31 : png_read_destroy(png_structrp png_ptr)
1010 : {
1011 : png_debug(1, "in png_read_destroy");
1012 :
1013 : #ifdef PNG_READ_GAMMA_SUPPORTED
1014 31 : png_destroy_gamma_table(png_ptr);
1015 : #endif
1016 :
1017 31 : png_free(png_ptr, png_ptr->big_row_buf);
1018 31 : png_ptr->big_row_buf = NULL;
1019 31 : png_free(png_ptr, png_ptr->big_prev_row);
1020 31 : png_ptr->big_prev_row = NULL;
1021 31 : png_free(png_ptr, png_ptr->read_buffer);
1022 31 : png_ptr->read_buffer = NULL;
1023 :
1024 : #ifdef PNG_READ_QUANTIZE_SUPPORTED
1025 : png_free(png_ptr, png_ptr->palette_lookup);
1026 : png_ptr->palette_lookup = NULL;
1027 : png_free(png_ptr, png_ptr->quantize_index);
1028 : png_ptr->quantize_index = NULL;
1029 : #endif
1030 :
1031 31 : if ((png_ptr->free_me & PNG_FREE_PLTE) != 0)
1032 : {
1033 0 : png_zfree(png_ptr, png_ptr->palette);
1034 0 : png_ptr->palette = NULL;
1035 : }
1036 31 : png_ptr->free_me &= ~PNG_FREE_PLTE;
1037 :
1038 : #if defined(PNG_tRNS_SUPPORTED) || \
1039 : defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
1040 31 : if ((png_ptr->free_me & PNG_FREE_TRNS) != 0)
1041 : {
1042 0 : png_free(png_ptr, png_ptr->trans_alpha);
1043 0 : png_ptr->trans_alpha = NULL;
1044 : }
1045 31 : png_ptr->free_me &= ~PNG_FREE_TRNS;
1046 : #endif
1047 :
1048 31 : inflateEnd(&png_ptr->zstream);
1049 :
1050 : #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1051 31 : png_free(png_ptr, png_ptr->save_buffer);
1052 31 : png_ptr->save_buffer = NULL;
1053 : #endif
1054 :
1055 : #if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) && \
1056 : defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED)
1057 : png_free(png_ptr, png_ptr->unknown_chunk.data);
1058 : png_ptr->unknown_chunk.data = NULL;
1059 : #endif
1060 :
1061 : #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
1062 : png_free(png_ptr, png_ptr->chunk_list);
1063 : png_ptr->chunk_list = NULL;
1064 : #endif
1065 :
1066 : /* NOTE: the 'setjmp' buffer may still be allocated and the memory and error
1067 : * callbacks are still set at this point. They are required to complete the
1068 : * destruction of the png_struct itself.
1069 : */
1070 31 : }
1071 :
1072 : /* Free all memory used by the read */
1073 : void PNGAPI
1074 31 : png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
1075 : png_infopp end_info_ptr_ptr)
1076 : {
1077 31 : png_structrp png_ptr = NULL;
1078 :
1079 : png_debug(1, "in png_destroy_read_struct");
1080 :
1081 31 : if (png_ptr_ptr != NULL)
1082 31 : png_ptr = *png_ptr_ptr;
1083 :
1084 31 : if (png_ptr == NULL)
1085 0 : return;
1086 :
1087 : /* libpng 1.6.0: use the API to destroy info structs to ensure consistent
1088 : * behavior. Prior to 1.6.0 libpng did extra 'info' destruction in this API.
1089 : * The extra was, apparently, unnecessary yet this hides memory leak bugs.
1090 : */
1091 31 : png_destroy_info_struct(png_ptr, end_info_ptr_ptr);
1092 31 : png_destroy_info_struct(png_ptr, info_ptr_ptr);
1093 :
1094 31 : *png_ptr_ptr = NULL;
1095 31 : png_read_destroy(png_ptr);
1096 31 : png_destroy_png_struct(png_ptr);
1097 : }
1098 :
1099 : void PNGAPI
1100 0 : png_set_read_status_fn(png_structrp png_ptr, png_read_status_ptr read_row_fn)
1101 : {
1102 0 : if (png_ptr == NULL)
1103 0 : return;
1104 :
1105 0 : png_ptr->read_row_fn = read_row_fn;
1106 : }
1107 :
1108 :
1109 : #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
1110 : #ifdef PNG_INFO_IMAGE_SUPPORTED
1111 : void PNGAPI
1112 : png_read_png(png_structrp png_ptr, png_inforp info_ptr,
1113 : int transforms, voidp params)
1114 : {
1115 : if (png_ptr == NULL || info_ptr == NULL)
1116 : return;
1117 :
1118 : /* png_read_info() gives us all of the information from the
1119 : * PNG file before the first IDAT (image data chunk).
1120 : */
1121 : png_read_info(png_ptr, info_ptr);
1122 : if (info_ptr->height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
1123 : png_error(png_ptr, "Image is too high to process with png_read_png()");
1124 :
1125 : /* -------------- image transformations start here ------------------- */
1126 : /* libpng 1.6.10: add code to cause a png_app_error if a selected TRANSFORM
1127 : * is not implemented. This will only happen in de-configured (non-default)
1128 : * libpng builds. The results can be unexpected - png_read_png may return
1129 : * short or mal-formed rows because the transform is skipped.
1130 : */
1131 :
1132 : /* Tell libpng to strip 16-bit/color files down to 8 bits per color.
1133 : */
1134 : if ((transforms & PNG_TRANSFORM_SCALE_16) != 0)
1135 : /* Added at libpng-1.5.4. "strip_16" produces the same result that it
1136 : * did in earlier versions, while "scale_16" is now more accurate.
1137 : */
1138 : #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1139 : png_set_scale_16(png_ptr);
1140 : #else
1141 : png_app_error(png_ptr, "PNG_TRANSFORM_SCALE_16 not supported");
1142 : #endif
1143 :
1144 : /* If both SCALE and STRIP are required pngrtran will effectively cancel the
1145 : * latter by doing SCALE first. This is ok and allows apps not to check for
1146 : * which is supported to get the right answer.
1147 : */
1148 : if ((transforms & PNG_TRANSFORM_STRIP_16) != 0)
1149 : #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1150 : png_set_strip_16(png_ptr);
1151 : #else
1152 : png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_16 not supported");
1153 : #endif
1154 :
1155 : /* Strip alpha bytes from the input data without combining with
1156 : * the background (not recommended).
1157 : */
1158 : if ((transforms & PNG_TRANSFORM_STRIP_ALPHA) != 0)
1159 : #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
1160 : png_set_strip_alpha(png_ptr);
1161 : #else
1162 : png_app_error(png_ptr, "PNG_TRANSFORM_STRIP_ALPHA not supported");
1163 : #endif
1164 :
1165 : /* Extract multiple pixels with bit depths of 1, 2, or 4 from a single
1166 : * byte into separate bytes (useful for paletted and grayscale images).
1167 : */
1168 : if ((transforms & PNG_TRANSFORM_PACKING) != 0)
1169 : #ifdef PNG_READ_PACK_SUPPORTED
1170 : png_set_packing(png_ptr);
1171 : #else
1172 : png_app_error(png_ptr, "PNG_TRANSFORM_PACKING not supported");
1173 : #endif
1174 :
1175 : /* Change the order of packed pixels to least significant bit first
1176 : * (not useful if you are using png_set_packing).
1177 : */
1178 : if ((transforms & PNG_TRANSFORM_PACKSWAP) != 0)
1179 : #ifdef PNG_READ_PACKSWAP_SUPPORTED
1180 : png_set_packswap(png_ptr);
1181 : #else
1182 : png_app_error(png_ptr, "PNG_TRANSFORM_PACKSWAP not supported");
1183 : #endif
1184 :
1185 : /* Expand paletted colors into true RGB triplets
1186 : * Expand grayscale images to full 8 bits from 1, 2, or 4 bits/pixel
1187 : * Expand paletted or RGB images with transparency to full alpha
1188 : * channels so the data will be available as RGBA quartets.
1189 : */
1190 : if ((transforms & PNG_TRANSFORM_EXPAND) != 0)
1191 : #ifdef PNG_READ_EXPAND_SUPPORTED
1192 : png_set_expand(png_ptr);
1193 : #else
1194 : png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND not supported");
1195 : #endif
1196 :
1197 : /* We don't handle background color or gamma transformation or quantizing.
1198 : */
1199 :
1200 : /* Invert monochrome files to have 0 as white and 1 as black
1201 : */
1202 : if ((transforms & PNG_TRANSFORM_INVERT_MONO) != 0)
1203 : #ifdef PNG_READ_INVERT_SUPPORTED
1204 : png_set_invert_mono(png_ptr);
1205 : #else
1206 : png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_MONO not supported");
1207 : #endif
1208 :
1209 : /* If you want to shift the pixel values from the range [0,255] or
1210 : * [0,65535] to the original [0,7] or [0,31], or whatever range the
1211 : * colors were originally in:
1212 : */
1213 : if ((transforms & PNG_TRANSFORM_SHIFT) != 0)
1214 : #ifdef PNG_READ_SHIFT_SUPPORTED
1215 : if ((info_ptr->valid & PNG_INFO_sBIT) != 0)
1216 : png_set_shift(png_ptr, &info_ptr->sig_bit);
1217 : #else
1218 : png_app_error(png_ptr, "PNG_TRANSFORM_SHIFT not supported");
1219 : #endif
1220 :
1221 : /* Flip the RGB pixels to BGR (or RGBA to BGRA) */
1222 : if ((transforms & PNG_TRANSFORM_BGR) != 0)
1223 : #ifdef PNG_READ_BGR_SUPPORTED
1224 : png_set_bgr(png_ptr);
1225 : #else
1226 : png_app_error(png_ptr, "PNG_TRANSFORM_BGR not supported");
1227 : #endif
1228 :
1229 : /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
1230 : if ((transforms & PNG_TRANSFORM_SWAP_ALPHA) != 0)
1231 : #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
1232 : png_set_swap_alpha(png_ptr);
1233 : #else
1234 : png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ALPHA not supported");
1235 : #endif
1236 :
1237 : /* Swap bytes of 16-bit files to least significant byte first */
1238 : if ((transforms & PNG_TRANSFORM_SWAP_ENDIAN) != 0)
1239 : #ifdef PNG_READ_SWAP_SUPPORTED
1240 : png_set_swap(png_ptr);
1241 : #else
1242 : png_app_error(png_ptr, "PNG_TRANSFORM_SWAP_ENDIAN not supported");
1243 : #endif
1244 :
1245 : /* Added at libpng-1.2.41 */
1246 : /* Invert the alpha channel from opacity to transparency */
1247 : if ((transforms & PNG_TRANSFORM_INVERT_ALPHA) != 0)
1248 : #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
1249 : png_set_invert_alpha(png_ptr);
1250 : #else
1251 : png_app_error(png_ptr, "PNG_TRANSFORM_INVERT_ALPHA not supported");
1252 : #endif
1253 :
1254 : /* Added at libpng-1.2.41 */
1255 : /* Expand grayscale image to RGB */
1256 : if ((transforms & PNG_TRANSFORM_GRAY_TO_RGB) != 0)
1257 : #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
1258 : png_set_gray_to_rgb(png_ptr);
1259 : #else
1260 : png_app_error(png_ptr, "PNG_TRANSFORM_GRAY_TO_RGB not supported");
1261 : #endif
1262 :
1263 : /* Added at libpng-1.5.4 */
1264 : if ((transforms & PNG_TRANSFORM_EXPAND_16) != 0)
1265 : #ifdef PNG_READ_EXPAND_16_SUPPORTED
1266 : png_set_expand_16(png_ptr);
1267 : #else
1268 : png_app_error(png_ptr, "PNG_TRANSFORM_EXPAND_16 not supported");
1269 : #endif
1270 :
1271 : /* We don't handle adding filler bytes */
1272 :
1273 : /* We use png_read_image and rely on that for interlace handling, but we also
1274 : * call png_read_update_info therefore must turn on interlace handling now:
1275 : */
1276 : (void)png_set_interlace_handling(png_ptr);
1277 :
1278 : /* Optional call to gamma correct and add the background to the palette
1279 : * and update info structure. REQUIRED if you are expecting libpng to
1280 : * update the palette for you (i.e., you selected such a transform above).
1281 : */
1282 : png_read_update_info(png_ptr, info_ptr);
1283 :
1284 : /* -------------- image transformations end here ------------------- */
1285 :
1286 : png_free_data(png_ptr, info_ptr, PNG_FREE_ROWS, 0);
1287 : if (info_ptr->row_pointers == NULL)
1288 : {
1289 : png_uint_32 iptr;
1290 :
1291 : info_ptr->row_pointers = png_voidcast(png_bytepp, png_malloc(png_ptr,
1292 : info_ptr->height * (sizeof (png_bytep))));
1293 :
1294 : for (iptr=0; iptr<info_ptr->height; iptr++)
1295 : info_ptr->row_pointers[iptr] = NULL;
1296 :
1297 : info_ptr->free_me |= PNG_FREE_ROWS;
1298 :
1299 : for (iptr = 0; iptr < info_ptr->height; iptr++)
1300 : info_ptr->row_pointers[iptr] = png_voidcast(png_bytep,
1301 : png_malloc(png_ptr, info_ptr->rowbytes));
1302 : }
1303 :
1304 : png_read_image(png_ptr, info_ptr->row_pointers);
1305 : info_ptr->valid |= PNG_INFO_IDAT;
1306 :
1307 : /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
1308 : png_read_end(png_ptr, info_ptr);
1309 :
1310 : PNG_UNUSED(params)
1311 : }
1312 : #endif /* INFO_IMAGE */
1313 : #endif /* SEQUENTIAL_READ */
1314 :
1315 : #ifdef PNG_SIMPLIFIED_READ_SUPPORTED
1316 : /* SIMPLIFIED READ
1317 : *
1318 : * This code currently relies on the sequential reader, though it could easily
1319 : * be made to work with the progressive one.
1320 : */
1321 : /* Arguments to png_image_finish_read: */
1322 :
1323 : /* Encoding of PNG data (used by the color-map code) */
1324 : # define P_NOTSET 0 /* File encoding not yet known */
1325 : # define P_sRGB 1 /* 8-bit encoded to sRGB gamma */
1326 : # define P_LINEAR 2 /* 16-bit linear: not encoded, NOT pre-multiplied! */
1327 : # define P_FILE 3 /* 8-bit encoded to file gamma, not sRGB or linear */
1328 : # define P_LINEAR8 4 /* 8-bit linear: only from a file value */
1329 :
1330 : /* Color-map processing: after libpng has run on the PNG image further
1331 : * processing may be needed to convert the data to color-map indices.
1332 : */
1333 : #define PNG_CMAP_NONE 0
1334 : #define PNG_CMAP_GA 1 /* Process GA data to a color-map with alpha */
1335 : #define PNG_CMAP_TRANS 2 /* Process GA data to a background index */
1336 : #define PNG_CMAP_RGB 3 /* Process RGB data */
1337 : #define PNG_CMAP_RGB_ALPHA 4 /* Process RGBA data */
1338 :
1339 : /* The following document where the background is for each processing case. */
1340 : #define PNG_CMAP_NONE_BACKGROUND 256
1341 : #define PNG_CMAP_GA_BACKGROUND 231
1342 : #define PNG_CMAP_TRANS_BACKGROUND 254
1343 : #define PNG_CMAP_RGB_BACKGROUND 256
1344 : #define PNG_CMAP_RGB_ALPHA_BACKGROUND 216
1345 :
1346 : typedef struct
1347 : {
1348 : /* Arguments: */
1349 : png_imagep image;
1350 : png_voidp buffer;
1351 : png_int_32 row_stride;
1352 : png_voidp colormap;
1353 : png_const_colorp background;
1354 : /* Local variables: */
1355 : png_voidp local_row;
1356 : png_voidp first_row;
1357 : ptrdiff_t row_bytes; /* step between rows */
1358 : int file_encoding; /* E_ values above */
1359 : png_fixed_point gamma_to_linear; /* For P_FILE, reciprocal of gamma */
1360 : int colormap_processing; /* PNG_CMAP_ values above */
1361 : } png_image_read_control;
1362 :
1363 : /* Do all the *safe* initialization - 'safe' means that png_error won't be
1364 : * called, so setting up the jmp_buf is not required. This means that anything
1365 : * called from here must *not* call png_malloc - it has to call png_malloc_warn
1366 : * instead so that control is returned safely back to this routine.
1367 : */
1368 : static int
1369 : png_image_read_init(png_imagep image)
1370 : {
1371 : if (image->opaque == NULL)
1372 : {
1373 : png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, image,
1374 : png_safe_error, png_safe_warning);
1375 :
1376 : /* And set the rest of the structure to NULL to ensure that the various
1377 : * fields are consistent.
1378 : */
1379 : memset(image, 0, (sizeof *image));
1380 : image->version = PNG_IMAGE_VERSION;
1381 :
1382 : if (png_ptr != NULL)
1383 : {
1384 : png_infop info_ptr = png_create_info_struct(png_ptr);
1385 :
1386 : if (info_ptr != NULL)
1387 : {
1388 : png_controlp control = png_voidcast(png_controlp,
1389 : png_malloc_warn(png_ptr, (sizeof *control)));
1390 :
1391 : if (control != NULL)
1392 : {
1393 : memset(control, 0, (sizeof *control));
1394 :
1395 : control->png_ptr = png_ptr;
1396 : control->info_ptr = info_ptr;
1397 : control->for_write = 0;
1398 :
1399 : image->opaque = control;
1400 : return 1;
1401 : }
1402 :
1403 : /* Error clean up */
1404 : png_destroy_info_struct(png_ptr, &info_ptr);
1405 : }
1406 :
1407 : png_destroy_read_struct(&png_ptr, NULL, NULL);
1408 : }
1409 :
1410 : return png_image_error(image, "png_image_read: out of memory");
1411 : }
1412 :
1413 : return png_image_error(image, "png_image_read: opaque pointer not NULL");
1414 : }
1415 :
1416 : /* Utility to find the base format of a PNG file from a png_struct. */
1417 : static png_uint_32
1418 : png_image_format(png_structrp png_ptr)
1419 : {
1420 : png_uint_32 format = 0;
1421 :
1422 : if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
1423 : format |= PNG_FORMAT_FLAG_COLOR;
1424 :
1425 : if ((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
1426 : format |= PNG_FORMAT_FLAG_ALPHA;
1427 :
1428 : /* Use png_ptr here, not info_ptr, because by examination png_handle_tRNS
1429 : * sets the png_struct fields; that's all we are interested in here. The
1430 : * precise interaction with an app call to png_set_tRNS and PNG file reading
1431 : * is unclear.
1432 : */
1433 : else if (png_ptr->num_trans > 0)
1434 : format |= PNG_FORMAT_FLAG_ALPHA;
1435 :
1436 : if (png_ptr->bit_depth == 16)
1437 : format |= PNG_FORMAT_FLAG_LINEAR;
1438 :
1439 : if ((png_ptr->color_type & PNG_COLOR_MASK_PALETTE) != 0)
1440 : format |= PNG_FORMAT_FLAG_COLORMAP;
1441 :
1442 : return format;
1443 : }
1444 :
1445 : /* Is the given gamma significantly different from sRGB? The test is the same
1446 : * one used in pngrtran.c when deciding whether to do gamma correction. The
1447 : * arithmetic optimizes the division by using the fact that the inverse of the
1448 : * file sRGB gamma is 2.2
1449 : */
1450 : static int
1451 : png_gamma_not_sRGB(png_fixed_point g)
1452 : {
1453 : if (g < PNG_FP_1)
1454 : {
1455 : /* An uninitialized gamma is assumed to be sRGB for the simplified API. */
1456 : if (g == 0)
1457 : return 0;
1458 :
1459 : return png_gamma_significant((g * 11 + 2)/5 /* i.e. *2.2, rounded */);
1460 : }
1461 :
1462 : return 1;
1463 : }
1464 :
1465 : /* Do the main body of a 'png_image_begin_read' function; read the PNG file
1466 : * header and fill in all the information. This is executed in a safe context,
1467 : * unlike the init routine above.
1468 : */
1469 : static int
1470 : png_image_read_header(png_voidp argument)
1471 : {
1472 : png_imagep image = png_voidcast(png_imagep, argument);
1473 : png_structrp png_ptr = image->opaque->png_ptr;
1474 : png_inforp info_ptr = image->opaque->info_ptr;
1475 :
1476 : #ifdef PNG_BENIGN_ERRORS_SUPPORTED
1477 : png_set_benign_errors(png_ptr, 1/*warn*/);
1478 : #endif
1479 : png_read_info(png_ptr, info_ptr);
1480 :
1481 : /* Do this the fast way; just read directly out of png_struct. */
1482 : image->width = png_ptr->width;
1483 : image->height = png_ptr->height;
1484 :
1485 : {
1486 : png_uint_32 format = png_image_format(png_ptr);
1487 :
1488 : image->format = format;
1489 :
1490 : #ifdef PNG_COLORSPACE_SUPPORTED
1491 : /* Does the colorspace match sRGB? If there is no color endpoint
1492 : * (colorant) information assume yes, otherwise require the
1493 : * 'ENDPOINTS_MATCHP_sRGB' colorspace flag to have been set. If the
1494 : * colorspace has been determined to be invalid ignore it.
1495 : */
1496 : if ((format & PNG_FORMAT_FLAG_COLOR) != 0 && ((png_ptr->colorspace.flags
1497 : & (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB|
1498 : PNG_COLORSPACE_INVALID)) == PNG_COLORSPACE_HAVE_ENDPOINTS))
1499 : image->flags |= PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB;
1500 : #endif
1501 : }
1502 :
1503 : /* We need the maximum number of entries regardless of the format the
1504 : * application sets here.
1505 : */
1506 : {
1507 : png_uint_32 cmap_entries;
1508 :
1509 : switch (png_ptr->color_type)
1510 : {
1511 : case PNG_COLOR_TYPE_GRAY:
1512 : cmap_entries = 1U << png_ptr->bit_depth;
1513 : break;
1514 :
1515 : case PNG_COLOR_TYPE_PALETTE:
1516 : cmap_entries = (png_uint_32)png_ptr->num_palette;
1517 : break;
1518 :
1519 : default:
1520 : cmap_entries = 256;
1521 : break;
1522 : }
1523 :
1524 : if (cmap_entries > 256)
1525 : cmap_entries = 256;
1526 :
1527 : image->colormap_entries = cmap_entries;
1528 : }
1529 :
1530 : return 1;
1531 : }
1532 :
1533 : #ifdef PNG_STDIO_SUPPORTED
1534 : int PNGAPI
1535 : png_image_begin_read_from_stdio(png_imagep image, FILE* file)
1536 : {
1537 : if (image != NULL && image->version == PNG_IMAGE_VERSION)
1538 : {
1539 : if (file != NULL)
1540 : {
1541 : if (png_image_read_init(image) != 0)
1542 : {
1543 : /* This is slightly evil, but png_init_io doesn't do anything other
1544 : * than this and we haven't changed the standard IO functions so
1545 : * this saves a 'safe' function.
1546 : */
1547 : image->opaque->png_ptr->io_ptr = file;
1548 : return png_safe_execute(image, png_image_read_header, image);
1549 : }
1550 : }
1551 :
1552 : else
1553 : return png_image_error(image,
1554 : "png_image_begin_read_from_stdio: invalid argument");
1555 : }
1556 :
1557 : else if (image != NULL)
1558 : return png_image_error(image,
1559 : "png_image_begin_read_from_stdio: incorrect PNG_IMAGE_VERSION");
1560 :
1561 : return 0;
1562 : }
1563 :
1564 : int PNGAPI
1565 : png_image_begin_read_from_file(png_imagep image, const char *file_name)
1566 : {
1567 : if (image != NULL && image->version == PNG_IMAGE_VERSION)
1568 : {
1569 : if (file_name != NULL)
1570 : {
1571 : FILE *fp = fopen(file_name, "rb");
1572 :
1573 : if (fp != NULL)
1574 : {
1575 : if (png_image_read_init(image) != 0)
1576 : {
1577 : image->opaque->png_ptr->io_ptr = fp;
1578 : image->opaque->owned_file = 1;
1579 : return png_safe_execute(image, png_image_read_header, image);
1580 : }
1581 :
1582 : /* Clean up: just the opened file. */
1583 : (void)fclose(fp);
1584 : }
1585 :
1586 : else
1587 : return png_image_error(image, strerror(errno));
1588 : }
1589 :
1590 : else
1591 : return png_image_error(image,
1592 : "png_image_begin_read_from_file: invalid argument");
1593 : }
1594 :
1595 : else if (image != NULL)
1596 : return png_image_error(image,
1597 : "png_image_begin_read_from_file: incorrect PNG_IMAGE_VERSION");
1598 :
1599 : return 0;
1600 : }
1601 : #endif /* STDIO */
1602 :
1603 : static void PNGCBAPI
1604 : png_image_memory_read(png_structp png_ptr, png_bytep out, png_size_t need)
1605 : {
1606 : if (png_ptr != NULL)
1607 : {
1608 : png_imagep image = png_voidcast(png_imagep, png_ptr->io_ptr);
1609 : if (image != NULL)
1610 : {
1611 : png_controlp cp = image->opaque;
1612 : if (cp != NULL)
1613 : {
1614 : png_const_bytep memory = cp->memory;
1615 : png_size_t size = cp->size;
1616 :
1617 : if (memory != NULL && size >= need)
1618 : {
1619 : memcpy(out, memory, need);
1620 : cp->memory = memory + need;
1621 : cp->size = size - need;
1622 : return;
1623 : }
1624 :
1625 : png_error(png_ptr, "read beyond end of data");
1626 : }
1627 : }
1628 :
1629 : png_error(png_ptr, "invalid memory read");
1630 : }
1631 : }
1632 :
1633 : int PNGAPI png_image_begin_read_from_memory(png_imagep image,
1634 : png_const_voidp memory, png_size_t size)
1635 : {
1636 : if (image != NULL && image->version == PNG_IMAGE_VERSION)
1637 : {
1638 : if (memory != NULL && size > 0)
1639 : {
1640 : if (png_image_read_init(image) != 0)
1641 : {
1642 : /* Now set the IO functions to read from the memory buffer and
1643 : * store it into io_ptr. Again do this in-place to avoid calling a
1644 : * libpng function that requires error handling.
1645 : */
1646 : image->opaque->memory = png_voidcast(png_const_bytep, memory);
1647 : image->opaque->size = size;
1648 : image->opaque->png_ptr->io_ptr = image;
1649 : image->opaque->png_ptr->read_data_fn = png_image_memory_read;
1650 :
1651 : return png_safe_execute(image, png_image_read_header, image);
1652 : }
1653 : }
1654 :
1655 : else
1656 : return png_image_error(image,
1657 : "png_image_begin_read_from_memory: invalid argument");
1658 : }
1659 :
1660 : else if (image != NULL)
1661 : return png_image_error(image,
1662 : "png_image_begin_read_from_memory: incorrect PNG_IMAGE_VERSION");
1663 :
1664 : return 0;
1665 : }
1666 :
1667 : /* Utility function to skip chunks that are not used by the simplified image
1668 : * read functions and an appropriate macro to call it.
1669 : */
1670 : #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1671 : static void
1672 : png_image_skip_unused_chunks(png_structrp png_ptr)
1673 : {
1674 : /* Prepare the reader to ignore all recognized chunks whose data will not
1675 : * be used, i.e., all chunks recognized by libpng except for those
1676 : * involved in basic image reading:
1677 : *
1678 : * IHDR, PLTE, IDAT, IEND
1679 : *
1680 : * Or image data handling:
1681 : *
1682 : * tRNS, bKGD, gAMA, cHRM, sRGB, [iCCP] and sBIT.
1683 : *
1684 : * This provides a small performance improvement and eliminates any
1685 : * potential vulnerability to security problems in the unused chunks.
1686 : *
1687 : * At present the iCCP chunk data isn't used, so iCCP chunk can be ignored
1688 : * too. This allows the simplified API to be compiled without iCCP support,
1689 : * however if the support is there the chunk is still checked to detect
1690 : * errors (which are unfortunately quite common.)
1691 : */
1692 : {
1693 : static PNG_CONST png_byte chunks_to_process[] = {
1694 : 98, 75, 71, 68, '\0', /* bKGD */
1695 : 99, 72, 82, 77, '\0', /* cHRM */
1696 : 103, 65, 77, 65, '\0', /* gAMA */
1697 : # ifdef PNG_READ_iCCP_SUPPORTED
1698 : 105, 67, 67, 80, '\0', /* iCCP */
1699 : # endif
1700 : 115, 66, 73, 84, '\0', /* sBIT */
1701 : 115, 82, 71, 66, '\0', /* sRGB */
1702 : };
1703 :
1704 : /* Ignore unknown chunks and all other chunks except for the
1705 : * IHDR, PLTE, tRNS, IDAT, and IEND chunks.
1706 : */
1707 : png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_NEVER,
1708 : NULL, -1);
1709 :
1710 : /* But do not ignore image data handling chunks */
1711 : png_set_keep_unknown_chunks(png_ptr, PNG_HANDLE_CHUNK_AS_DEFAULT,
1712 : chunks_to_process, (int)/*SAFE*/(sizeof chunks_to_process)/5);
1713 : }
1714 : }
1715 :
1716 : # define PNG_SKIP_CHUNKS(p) png_image_skip_unused_chunks(p)
1717 : #else
1718 : # define PNG_SKIP_CHUNKS(p) ((void)0)
1719 : #endif /* HANDLE_AS_UNKNOWN */
1720 :
1721 : /* The following macro gives the exact rounded answer for all values in the
1722 : * range 0..255 (it actually divides by 51.2, but the rounding still generates
1723 : * the correct numbers 0..5
1724 : */
1725 : #define PNG_DIV51(v8) (((v8) * 5 + 130) >> 8)
1726 :
1727 : /* Utility functions to make particular color-maps */
1728 : static void
1729 : set_file_encoding(png_image_read_control *display)
1730 : {
1731 : png_fixed_point g = display->image->opaque->png_ptr->colorspace.gamma;
1732 : if (png_gamma_significant(g) != 0)
1733 : {
1734 : if (png_gamma_not_sRGB(g) != 0)
1735 : {
1736 : display->file_encoding = P_FILE;
1737 : display->gamma_to_linear = png_reciprocal(g);
1738 : }
1739 :
1740 : else
1741 : display->file_encoding = P_sRGB;
1742 : }
1743 :
1744 : else
1745 : display->file_encoding = P_LINEAR8;
1746 : }
1747 :
1748 : static unsigned int
1749 : decode_gamma(png_image_read_control *display, png_uint_32 value, int encoding)
1750 : {
1751 : if (encoding == P_FILE) /* double check */
1752 : encoding = display->file_encoding;
1753 :
1754 : if (encoding == P_NOTSET) /* must be the file encoding */
1755 : {
1756 : set_file_encoding(display);
1757 : encoding = display->file_encoding;
1758 : }
1759 :
1760 : switch (encoding)
1761 : {
1762 : case P_FILE:
1763 : value = png_gamma_16bit_correct(value*257, display->gamma_to_linear);
1764 : break;
1765 :
1766 : case P_sRGB:
1767 : value = png_sRGB_table[value];
1768 : break;
1769 :
1770 : case P_LINEAR:
1771 : break;
1772 :
1773 : case P_LINEAR8:
1774 : value *= 257;
1775 : break;
1776 :
1777 : #ifdef __GNUC__
1778 : default:
1779 : png_error(display->image->opaque->png_ptr,
1780 : "unexpected encoding (internal error)");
1781 : #endif
1782 : }
1783 :
1784 : return value;
1785 : }
1786 :
1787 : static png_uint_32
1788 : png_colormap_compose(png_image_read_control *display,
1789 : png_uint_32 foreground, int foreground_encoding, png_uint_32 alpha,
1790 : png_uint_32 background, int encoding)
1791 : {
1792 : /* The file value is composed on the background, the background has the given
1793 : * encoding and so does the result, the file is encoded with P_FILE and the
1794 : * file and alpha are 8-bit values. The (output) encoding will always be
1795 : * P_LINEAR or P_sRGB.
1796 : */
1797 : png_uint_32 f = decode_gamma(display, foreground, foreground_encoding);
1798 : png_uint_32 b = decode_gamma(display, background, encoding);
1799 :
1800 : /* The alpha is always an 8-bit value (it comes from the palette), the value
1801 : * scaled by 255 is what PNG_sRGB_FROM_LINEAR requires.
1802 : */
1803 : f = f * alpha + b * (255-alpha);
1804 :
1805 : if (encoding == P_LINEAR)
1806 : {
1807 : /* Scale to 65535; divide by 255, approximately (in fact this is extremely
1808 : * accurate, it divides by 255.00000005937181414556, with no overflow.)
1809 : */
1810 : f *= 257; /* Now scaled by 65535 */
1811 : f += f >> 16;
1812 : f = (f+32768) >> 16;
1813 : }
1814 :
1815 : else /* P_sRGB */
1816 : f = PNG_sRGB_FROM_LINEAR(f);
1817 :
1818 : return f;
1819 : }
1820 :
1821 : /* NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must
1822 : * be 8-bit.
1823 : */
1824 : static void
1825 : png_create_colormap_entry(png_image_read_control *display,
1826 : png_uint_32 ip, png_uint_32 red, png_uint_32 green, png_uint_32 blue,
1827 : png_uint_32 alpha, int encoding)
1828 : {
1829 : png_imagep image = display->image;
1830 : const int output_encoding = (image->format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
1831 : P_LINEAR : P_sRGB;
1832 : const int convert_to_Y = (image->format & PNG_FORMAT_FLAG_COLOR) == 0 &&
1833 : (red != green || green != blue);
1834 :
1835 : if (ip > 255)
1836 : png_error(image->opaque->png_ptr, "color-map index out of range");
1837 :
1838 : /* Update the cache with whether the file gamma is significantly different
1839 : * from sRGB.
1840 : */
1841 : if (encoding == P_FILE)
1842 : {
1843 : if (display->file_encoding == P_NOTSET)
1844 : set_file_encoding(display);
1845 :
1846 : /* Note that the cached value may be P_FILE too, but if it is then the
1847 : * gamma_to_linear member has been set.
1848 : */
1849 : encoding = display->file_encoding;
1850 : }
1851 :
1852 : if (encoding == P_FILE)
1853 : {
1854 : png_fixed_point g = display->gamma_to_linear;
1855 :
1856 : red = png_gamma_16bit_correct(red*257, g);
1857 : green = png_gamma_16bit_correct(green*257, g);
1858 : blue = png_gamma_16bit_correct(blue*257, g);
1859 :
1860 : if (convert_to_Y != 0 || output_encoding == P_LINEAR)
1861 : {
1862 : alpha *= 257;
1863 : encoding = P_LINEAR;
1864 : }
1865 :
1866 : else
1867 : {
1868 : red = PNG_sRGB_FROM_LINEAR(red * 255);
1869 : green = PNG_sRGB_FROM_LINEAR(green * 255);
1870 : blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1871 : encoding = P_sRGB;
1872 : }
1873 : }
1874 :
1875 : else if (encoding == P_LINEAR8)
1876 : {
1877 : /* This encoding occurs quite frequently in test cases because PngSuite
1878 : * includes a gAMA 1.0 chunk with most images.
1879 : */
1880 : red *= 257;
1881 : green *= 257;
1882 : blue *= 257;
1883 : alpha *= 257;
1884 : encoding = P_LINEAR;
1885 : }
1886 :
1887 : else if (encoding == P_sRGB &&
1888 : (convert_to_Y != 0 || output_encoding == P_LINEAR))
1889 : {
1890 : /* The values are 8-bit sRGB values, but must be converted to 16-bit
1891 : * linear.
1892 : */
1893 : red = png_sRGB_table[red];
1894 : green = png_sRGB_table[green];
1895 : blue = png_sRGB_table[blue];
1896 : alpha *= 257;
1897 : encoding = P_LINEAR;
1898 : }
1899 :
1900 : /* This is set if the color isn't gray but the output is. */
1901 : if (encoding == P_LINEAR)
1902 : {
1903 : if (convert_to_Y != 0)
1904 : {
1905 : /* NOTE: these values are copied from png_do_rgb_to_gray */
1906 : png_uint_32 y = (png_uint_32)6968 * red + (png_uint_32)23434 * green +
1907 : (png_uint_32)2366 * blue;
1908 :
1909 : if (output_encoding == P_LINEAR)
1910 : y = (y + 16384) >> 15;
1911 :
1912 : else
1913 : {
1914 : /* y is scaled by 32768, we need it scaled by 255: */
1915 : y = (y + 128) >> 8;
1916 : y *= 255;
1917 : y = PNG_sRGB_FROM_LINEAR((y + 64) >> 7);
1918 : alpha = PNG_DIV257(alpha);
1919 : encoding = P_sRGB;
1920 : }
1921 :
1922 : blue = red = green = y;
1923 : }
1924 :
1925 : else if (output_encoding == P_sRGB)
1926 : {
1927 : red = PNG_sRGB_FROM_LINEAR(red * 255);
1928 : green = PNG_sRGB_FROM_LINEAR(green * 255);
1929 : blue = PNG_sRGB_FROM_LINEAR(blue * 255);
1930 : alpha = PNG_DIV257(alpha);
1931 : encoding = P_sRGB;
1932 : }
1933 : }
1934 :
1935 : if (encoding != output_encoding)
1936 : png_error(image->opaque->png_ptr, "bad encoding (internal error)");
1937 :
1938 : /* Store the value. */
1939 : {
1940 : # ifdef PNG_FORMAT_AFIRST_SUPPORTED
1941 : const int afirst = (image->format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
1942 : (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
1943 : # else
1944 : # define afirst 0
1945 : # endif
1946 : # ifdef PNG_FORMAT_BGR_SUPPORTED
1947 : const int bgr = (image->format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
1948 : # else
1949 : # define bgr 0
1950 : # endif
1951 :
1952 : if (output_encoding == P_LINEAR)
1953 : {
1954 : png_uint_16p entry = png_voidcast(png_uint_16p, display->colormap);
1955 :
1956 : entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
1957 :
1958 : /* The linear 16-bit values must be pre-multiplied by the alpha channel
1959 : * value, if less than 65535 (this is, effectively, composite on black
1960 : * if the alpha channel is removed.)
1961 : */
1962 : switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
1963 : {
1964 : case 4:
1965 : entry[afirst ? 0 : 3] = (png_uint_16)alpha;
1966 : /* FALL THROUGH */
1967 :
1968 : case 3:
1969 : if (alpha < 65535)
1970 : {
1971 : if (alpha > 0)
1972 : {
1973 : blue = (blue * alpha + 32767U)/65535U;
1974 : green = (green * alpha + 32767U)/65535U;
1975 : red = (red * alpha + 32767U)/65535U;
1976 : }
1977 :
1978 : else
1979 : red = green = blue = 0;
1980 : }
1981 : entry[afirst + (2 ^ bgr)] = (png_uint_16)blue;
1982 : entry[afirst + 1] = (png_uint_16)green;
1983 : entry[afirst + bgr] = (png_uint_16)red;
1984 : break;
1985 :
1986 : case 2:
1987 : entry[1 ^ afirst] = (png_uint_16)alpha;
1988 : /* FALL THROUGH */
1989 :
1990 : case 1:
1991 : if (alpha < 65535)
1992 : {
1993 : if (alpha > 0)
1994 : green = (green * alpha + 32767U)/65535U;
1995 :
1996 : else
1997 : green = 0;
1998 : }
1999 : entry[afirst] = (png_uint_16)green;
2000 : break;
2001 :
2002 : default:
2003 : break;
2004 : }
2005 : }
2006 :
2007 : else /* output encoding is P_sRGB */
2008 : {
2009 : png_bytep entry = png_voidcast(png_bytep, display->colormap);
2010 :
2011 : entry += ip * PNG_IMAGE_SAMPLE_CHANNELS(image->format);
2012 :
2013 : switch (PNG_IMAGE_SAMPLE_CHANNELS(image->format))
2014 : {
2015 : case 4:
2016 : entry[afirst ? 0 : 3] = (png_byte)alpha;
2017 : case 3:
2018 : entry[afirst + (2 ^ bgr)] = (png_byte)blue;
2019 : entry[afirst + 1] = (png_byte)green;
2020 : entry[afirst + bgr] = (png_byte)red;
2021 : break;
2022 :
2023 : case 2:
2024 : entry[1 ^ afirst] = (png_byte)alpha;
2025 : case 1:
2026 : entry[afirst] = (png_byte)green;
2027 : break;
2028 :
2029 : default:
2030 : break;
2031 : }
2032 : }
2033 :
2034 : # ifdef afirst
2035 : # undef afirst
2036 : # endif
2037 : # ifdef bgr
2038 : # undef bgr
2039 : # endif
2040 : }
2041 : }
2042 :
2043 : static int
2044 : make_gray_file_colormap(png_image_read_control *display)
2045 : {
2046 : unsigned int i;
2047 :
2048 : for (i=0; i<256; ++i)
2049 : png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
2050 :
2051 : return (int)i;
2052 : }
2053 :
2054 : static int
2055 : make_gray_colormap(png_image_read_control *display)
2056 : {
2057 : unsigned int i;
2058 :
2059 : for (i=0; i<256; ++i)
2060 : png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
2061 :
2062 : return (int)i;
2063 : }
2064 : #define PNG_GRAY_COLORMAP_ENTRIES 256
2065 :
2066 : static int
2067 : make_ga_colormap(png_image_read_control *display)
2068 : {
2069 : unsigned int i, a;
2070 :
2071 : /* Alpha is retained, the output will be a color-map with entries
2072 : * selected by six levels of alpha. One transparent entry, 6 gray
2073 : * levels for all the intermediate alpha values, leaving 230 entries
2074 : * for the opaque grays. The color-map entries are the six values
2075 : * [0..5]*51, the GA processing uses PNG_DIV51(value) to find the
2076 : * relevant entry.
2077 : *
2078 : * if (alpha > 229) // opaque
2079 : * {
2080 : * // The 231 entries are selected to make the math below work:
2081 : * base = 0;
2082 : * entry = (231 * gray + 128) >> 8;
2083 : * }
2084 : * else if (alpha < 26) // transparent
2085 : * {
2086 : * base = 231;
2087 : * entry = 0;
2088 : * }
2089 : * else // partially opaque
2090 : * {
2091 : * base = 226 + 6 * PNG_DIV51(alpha);
2092 : * entry = PNG_DIV51(gray);
2093 : * }
2094 : */
2095 : i = 0;
2096 : while (i < 231)
2097 : {
2098 : unsigned int gray = (i * 256 + 115) / 231;
2099 : png_create_colormap_entry(display, i++, gray, gray, gray, 255, P_sRGB);
2100 : }
2101 :
2102 : /* 255 is used here for the component values for consistency with the code
2103 : * that undoes premultiplication in pngwrite.c.
2104 : */
2105 : png_create_colormap_entry(display, i++, 255, 255, 255, 0, P_sRGB);
2106 :
2107 : for (a=1; a<5; ++a)
2108 : {
2109 : unsigned int g;
2110 :
2111 : for (g=0; g<6; ++g)
2112 : png_create_colormap_entry(display, i++, g*51, g*51, g*51, a*51,
2113 : P_sRGB);
2114 : }
2115 :
2116 : return (int)i;
2117 : }
2118 :
2119 : #define PNG_GA_COLORMAP_ENTRIES 256
2120 :
2121 : static int
2122 : make_rgb_colormap(png_image_read_control *display)
2123 : {
2124 : unsigned int i, r;
2125 :
2126 : /* Build a 6x6x6 opaque RGB cube */
2127 : for (i=r=0; r<6; ++r)
2128 : {
2129 : unsigned int g;
2130 :
2131 : for (g=0; g<6; ++g)
2132 : {
2133 : unsigned int b;
2134 :
2135 : for (b=0; b<6; ++b)
2136 : png_create_colormap_entry(display, i++, r*51, g*51, b*51, 255,
2137 : P_sRGB);
2138 : }
2139 : }
2140 :
2141 : return (int)i;
2142 : }
2143 :
2144 : #define PNG_RGB_COLORMAP_ENTRIES 216
2145 :
2146 : /* Return a palette index to the above palette given three 8-bit sRGB values. */
2147 : #define PNG_RGB_INDEX(r,g,b) \
2148 : ((png_byte)(6 * (6 * PNG_DIV51(r) + PNG_DIV51(g)) + PNG_DIV51(b)))
2149 :
2150 : static int
2151 : png_image_read_colormap(png_voidp argument)
2152 : {
2153 : png_image_read_control *display =
2154 : png_voidcast(png_image_read_control*, argument);
2155 : const png_imagep image = display->image;
2156 :
2157 : const png_structrp png_ptr = image->opaque->png_ptr;
2158 : const png_uint_32 output_format = image->format;
2159 : const int output_encoding = (output_format & PNG_FORMAT_FLAG_LINEAR) != 0 ?
2160 : P_LINEAR : P_sRGB;
2161 :
2162 : unsigned int cmap_entries;
2163 : unsigned int output_processing; /* Output processing option */
2164 : unsigned int data_encoding = P_NOTSET; /* Encoding libpng must produce */
2165 :
2166 : /* Background information; the background color and the index of this color
2167 : * in the color-map if it exists (else 256).
2168 : */
2169 : unsigned int background_index = 256;
2170 : png_uint_32 back_r, back_g, back_b;
2171 :
2172 : /* Flags to accumulate things that need to be done to the input. */
2173 : int expand_tRNS = 0;
2174 :
2175 : /* Exclude the NYI feature of compositing onto a color-mapped buffer; it is
2176 : * very difficult to do, the results look awful, and it is difficult to see
2177 : * what possible use it is because the application can't control the
2178 : * color-map.
2179 : */
2180 : if (((png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0 ||
2181 : png_ptr->num_trans > 0) /* alpha in input */ &&
2182 : ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0) /* no alpha in output */)
2183 : {
2184 : if (output_encoding == P_LINEAR) /* compose on black */
2185 : back_b = back_g = back_r = 0;
2186 :
2187 : else if (display->background == NULL /* no way to remove it */)
2188 : png_error(png_ptr,
2189 : "background color must be supplied to remove alpha/transparency");
2190 :
2191 : /* Get a copy of the background color (this avoids repeating the checks
2192 : * below.) The encoding is 8-bit sRGB or 16-bit linear, depending on the
2193 : * output format.
2194 : */
2195 : else
2196 : {
2197 : back_g = display->background->green;
2198 : if ((output_format & PNG_FORMAT_FLAG_COLOR) != 0)
2199 : {
2200 : back_r = display->background->red;
2201 : back_b = display->background->blue;
2202 : }
2203 : else
2204 : back_b = back_r = back_g;
2205 : }
2206 : }
2207 :
2208 : else if (output_encoding == P_LINEAR)
2209 : back_b = back_r = back_g = 65535;
2210 :
2211 : else
2212 : back_b = back_r = back_g = 255;
2213 :
2214 : /* Default the input file gamma if required - this is necessary because
2215 : * libpng assumes that if no gamma information is present the data is in the
2216 : * output format, but the simplified API deduces the gamma from the input
2217 : * format.
2218 : */
2219 : if ((png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) == 0)
2220 : {
2221 : /* Do this directly, not using the png_colorspace functions, to ensure
2222 : * that it happens even if the colorspace is invalid (though probably if
2223 : * it is the setting will be ignored) Note that the same thing can be
2224 : * achieved at the application interface with png_set_gAMA.
2225 : */
2226 : if (png_ptr->bit_depth == 16 &&
2227 : (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
2228 : png_ptr->colorspace.gamma = PNG_GAMMA_LINEAR;
2229 :
2230 : else
2231 : png_ptr->colorspace.gamma = PNG_GAMMA_sRGB_INVERSE;
2232 :
2233 : png_ptr->colorspace.flags |= PNG_COLORSPACE_HAVE_GAMMA;
2234 : }
2235 :
2236 : /* Decide what to do based on the PNG color type of the input data. The
2237 : * utility function png_create_colormap_entry deals with most aspects of the
2238 : * output transformations; this code works out how to produce bytes of
2239 : * color-map entries from the original format.
2240 : */
2241 : switch (png_ptr->color_type)
2242 : {
2243 : case PNG_COLOR_TYPE_GRAY:
2244 : if (png_ptr->bit_depth <= 8)
2245 : {
2246 : /* There at most 256 colors in the output, regardless of
2247 : * transparency.
2248 : */
2249 : unsigned int step, i, val, trans = 256/*ignore*/, back_alpha = 0;
2250 :
2251 : cmap_entries = 1U << png_ptr->bit_depth;
2252 : if (cmap_entries > image->colormap_entries)
2253 : png_error(png_ptr, "gray[8] color-map: too few entries");
2254 :
2255 : step = 255 / (cmap_entries - 1);
2256 : output_processing = PNG_CMAP_NONE;
2257 :
2258 : /* If there is a tRNS chunk then this either selects a transparent
2259 : * value or, if the output has no alpha, the background color.
2260 : */
2261 : if (png_ptr->num_trans > 0)
2262 : {
2263 : trans = png_ptr->trans_color.gray;
2264 :
2265 : if ((output_format & PNG_FORMAT_FLAG_ALPHA) == 0)
2266 : back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2267 : }
2268 :
2269 : /* png_create_colormap_entry just takes an RGBA and writes the
2270 : * corresponding color-map entry using the format from 'image',
2271 : * including the required conversion to sRGB or linear as
2272 : * appropriate. The input values are always either sRGB (if the
2273 : * gamma correction flag is 0) or 0..255 scaled file encoded values
2274 : * (if the function must gamma correct them).
2275 : */
2276 : for (i=val=0; i<cmap_entries; ++i, val += step)
2277 : {
2278 : /* 'i' is a file value. While this will result in duplicated
2279 : * entries for 8-bit non-sRGB encoded files it is necessary to
2280 : * have non-gamma corrected values to do tRNS handling.
2281 : */
2282 : if (i != trans)
2283 : png_create_colormap_entry(display, i, val, val, val, 255,
2284 : P_FILE/*8-bit with file gamma*/);
2285 :
2286 : /* Else this entry is transparent. The colors don't matter if
2287 : * there is an alpha channel (back_alpha == 0), but it does no
2288 : * harm to pass them in; the values are not set above so this
2289 : * passes in white.
2290 : *
2291 : * NOTE: this preserves the full precision of the application
2292 : * supplied background color when it is used.
2293 : */
2294 : else
2295 : png_create_colormap_entry(display, i, back_r, back_g, back_b,
2296 : back_alpha, output_encoding);
2297 : }
2298 :
2299 : /* We need libpng to preserve the original encoding. */
2300 : data_encoding = P_FILE;
2301 :
2302 : /* The rows from libpng, while technically gray values, are now also
2303 : * color-map indices; however, they may need to be expanded to 1
2304 : * byte per pixel. This is what png_set_packing does (i.e., it
2305 : * unpacks the bit values into bytes.)
2306 : */
2307 : if (png_ptr->bit_depth < 8)
2308 : png_set_packing(png_ptr);
2309 : }
2310 :
2311 : else /* bit depth is 16 */
2312 : {
2313 : /* The 16-bit input values can be converted directly to 8-bit gamma
2314 : * encoded values; however, if a tRNS chunk is present 257 color-map
2315 : * entries are required. This means that the extra entry requires
2316 : * special processing; add an alpha channel, sacrifice gray level
2317 : * 254 and convert transparent (alpha==0) entries to that.
2318 : *
2319 : * Use libpng to chop the data to 8 bits. Convert it to sRGB at the
2320 : * same time to minimize quality loss. If a tRNS chunk is present
2321 : * this means libpng must handle it too; otherwise it is impossible
2322 : * to do the exact match on the 16-bit value.
2323 : *
2324 : * If the output has no alpha channel *and* the background color is
2325 : * gray then it is possible to let libpng handle the substitution by
2326 : * ensuring that the corresponding gray level matches the background
2327 : * color exactly.
2328 : */
2329 : data_encoding = P_sRGB;
2330 :
2331 : if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2332 : png_error(png_ptr, "gray[16] color-map: too few entries");
2333 :
2334 : cmap_entries = (unsigned int)make_gray_colormap(display);
2335 :
2336 : if (png_ptr->num_trans > 0)
2337 : {
2338 : unsigned int back_alpha;
2339 :
2340 : if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2341 : back_alpha = 0;
2342 :
2343 : else
2344 : {
2345 : if (back_r == back_g && back_g == back_b)
2346 : {
2347 : /* Background is gray; no special processing will be
2348 : * required.
2349 : */
2350 : png_color_16 c;
2351 : png_uint_32 gray = back_g;
2352 :
2353 : if (output_encoding == P_LINEAR)
2354 : {
2355 : gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2356 :
2357 : /* And make sure the corresponding palette entry
2358 : * matches.
2359 : */
2360 : png_create_colormap_entry(display, gray, back_g, back_g,
2361 : back_g, 65535, P_LINEAR);
2362 : }
2363 :
2364 : /* The background passed to libpng, however, must be the
2365 : * sRGB value.
2366 : */
2367 : c.index = 0; /*unused*/
2368 : c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2369 :
2370 : /* NOTE: does this work without expanding tRNS to alpha?
2371 : * It should be the color->gray case below apparently
2372 : * doesn't.
2373 : */
2374 : png_set_background_fixed(png_ptr, &c,
2375 : PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2376 : 0/*gamma: not used*/);
2377 :
2378 : output_processing = PNG_CMAP_NONE;
2379 : break;
2380 : }
2381 : #ifdef __COVERITY__
2382 : /* Coverity claims that output_encoding cannot be 2 (P_LINEAR)
2383 : * here.
2384 : */
2385 : back_alpha = 255;
2386 : #else
2387 : back_alpha = output_encoding == P_LINEAR ? 65535 : 255;
2388 : #endif
2389 : }
2390 :
2391 : /* output_processing means that the libpng-processed row will be
2392 : * 8-bit GA and it has to be processing to single byte color-map
2393 : * values. Entry 254 is replaced by either a completely
2394 : * transparent entry or by the background color at full
2395 : * precision (and the background color is not a simple gray
2396 : * level in this case.)
2397 : */
2398 : expand_tRNS = 1;
2399 : output_processing = PNG_CMAP_TRANS;
2400 : background_index = 254;
2401 :
2402 : /* And set (overwrite) color-map entry 254 to the actual
2403 : * background color at full precision.
2404 : */
2405 : png_create_colormap_entry(display, 254, back_r, back_g, back_b,
2406 : back_alpha, output_encoding);
2407 : }
2408 :
2409 : else
2410 : output_processing = PNG_CMAP_NONE;
2411 : }
2412 : break;
2413 :
2414 : case PNG_COLOR_TYPE_GRAY_ALPHA:
2415 : /* 8-bit or 16-bit PNG with two channels - gray and alpha. A minimum
2416 : * of 65536 combinations. If, however, the alpha channel is to be
2417 : * removed there are only 256 possibilities if the background is gray.
2418 : * (Otherwise there is a subset of the 65536 possibilities defined by
2419 : * the triangle between black, white and the background color.)
2420 : *
2421 : * Reduce 16-bit files to 8-bit and sRGB encode the result. No need to
2422 : * worry about tRNS matching - tRNS is ignored if there is an alpha
2423 : * channel.
2424 : */
2425 : data_encoding = P_sRGB;
2426 :
2427 : if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2428 : {
2429 : if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2430 : png_error(png_ptr, "gray+alpha color-map: too few entries");
2431 :
2432 : cmap_entries = (unsigned int)make_ga_colormap(display);
2433 :
2434 : background_index = PNG_CMAP_GA_BACKGROUND;
2435 : output_processing = PNG_CMAP_GA;
2436 : }
2437 :
2438 : else /* alpha is removed */
2439 : {
2440 : /* Alpha must be removed as the PNG data is processed when the
2441 : * background is a color because the G and A channels are
2442 : * independent and the vector addition (non-parallel vectors) is a
2443 : * 2-D problem.
2444 : *
2445 : * This can be reduced to the same algorithm as above by making a
2446 : * colormap containing gray levels (for the opaque grays), a
2447 : * background entry (for a transparent pixel) and a set of four six
2448 : * level color values, one set for each intermediate alpha value.
2449 : * See the comments in make_ga_colormap for how this works in the
2450 : * per-pixel processing.
2451 : *
2452 : * If the background is gray, however, we only need a 256 entry gray
2453 : * level color map. It is sufficient to make the entry generated
2454 : * for the background color be exactly the color specified.
2455 : */
2456 : if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0 ||
2457 : (back_r == back_g && back_g == back_b))
2458 : {
2459 : /* Background is gray; no special processing will be required. */
2460 : png_color_16 c;
2461 : png_uint_32 gray = back_g;
2462 :
2463 : if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2464 : png_error(png_ptr, "gray-alpha color-map: too few entries");
2465 :
2466 : cmap_entries = (unsigned int)make_gray_colormap(display);
2467 :
2468 : if (output_encoding == P_LINEAR)
2469 : {
2470 : gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2471 :
2472 : /* And make sure the corresponding palette entry matches. */
2473 : png_create_colormap_entry(display, gray, back_g, back_g,
2474 : back_g, 65535, P_LINEAR);
2475 : }
2476 :
2477 : /* The background passed to libpng, however, must be the sRGB
2478 : * value.
2479 : */
2480 : c.index = 0; /*unused*/
2481 : c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2482 :
2483 : png_set_background_fixed(png_ptr, &c,
2484 : PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2485 : 0/*gamma: not used*/);
2486 :
2487 : output_processing = PNG_CMAP_NONE;
2488 : }
2489 :
2490 : else
2491 : {
2492 : png_uint_32 i, a;
2493 :
2494 : /* This is the same as png_make_ga_colormap, above, except that
2495 : * the entries are all opaque.
2496 : */
2497 : if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2498 : png_error(png_ptr, "ga-alpha color-map: too few entries");
2499 :
2500 : i = 0;
2501 : while (i < 231)
2502 : {
2503 : png_uint_32 gray = (i * 256 + 115) / 231;
2504 : png_create_colormap_entry(display, i++, gray, gray, gray,
2505 : 255, P_sRGB);
2506 : }
2507 :
2508 : /* NOTE: this preserves the full precision of the application
2509 : * background color.
2510 : */
2511 : background_index = i;
2512 : png_create_colormap_entry(display, i++, back_r, back_g, back_b,
2513 : #ifdef __COVERITY__
2514 : /* Coverity claims that output_encoding
2515 : * cannot be 2 (P_LINEAR) here.
2516 : */ 255U,
2517 : #else
2518 : output_encoding == P_LINEAR ? 65535U : 255U,
2519 : #endif
2520 : output_encoding);
2521 :
2522 : /* For non-opaque input composite on the sRGB background - this
2523 : * requires inverting the encoding for each component. The input
2524 : * is still converted to the sRGB encoding because this is a
2525 : * reasonable approximate to the logarithmic curve of human
2526 : * visual sensitivity, at least over the narrow range which PNG
2527 : * represents. Consequently 'G' is always sRGB encoded, while
2528 : * 'A' is linear. We need the linear background colors.
2529 : */
2530 : if (output_encoding == P_sRGB) /* else already linear */
2531 : {
2532 : /* This may produce a value not exactly matching the
2533 : * background, but that's ok because these numbers are only
2534 : * used when alpha != 0
2535 : */
2536 : back_r = png_sRGB_table[back_r];
2537 : back_g = png_sRGB_table[back_g];
2538 : back_b = png_sRGB_table[back_b];
2539 : }
2540 :
2541 : for (a=1; a<5; ++a)
2542 : {
2543 : unsigned int g;
2544 :
2545 : /* PNG_sRGB_FROM_LINEAR expects a 16-bit linear value scaled
2546 : * by an 8-bit alpha value (0..255).
2547 : */
2548 : png_uint_32 alpha = 51 * a;
2549 : png_uint_32 back_rx = (255-alpha) * back_r;
2550 : png_uint_32 back_gx = (255-alpha) * back_g;
2551 : png_uint_32 back_bx = (255-alpha) * back_b;
2552 :
2553 : for (g=0; g<6; ++g)
2554 : {
2555 : png_uint_32 gray = png_sRGB_table[g*51] * alpha;
2556 :
2557 : png_create_colormap_entry(display, i++,
2558 : PNG_sRGB_FROM_LINEAR(gray + back_rx),
2559 : PNG_sRGB_FROM_LINEAR(gray + back_gx),
2560 : PNG_sRGB_FROM_LINEAR(gray + back_bx), 255, P_sRGB);
2561 : }
2562 : }
2563 :
2564 : cmap_entries = i;
2565 : output_processing = PNG_CMAP_GA;
2566 : }
2567 : }
2568 : break;
2569 :
2570 : case PNG_COLOR_TYPE_RGB:
2571 : case PNG_COLOR_TYPE_RGB_ALPHA:
2572 : /* Exclude the case where the output is gray; we can always handle this
2573 : * with the cases above.
2574 : */
2575 : if ((output_format & PNG_FORMAT_FLAG_COLOR) == 0)
2576 : {
2577 : /* The color-map will be grayscale, so we may as well convert the
2578 : * input RGB values to a simple grayscale and use the grayscale
2579 : * code above.
2580 : *
2581 : * NOTE: calling this apparently damages the recognition of the
2582 : * transparent color in background color handling; call
2583 : * png_set_tRNS_to_alpha before png_set_background_fixed.
2584 : */
2585 : png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE, -1,
2586 : -1);
2587 : data_encoding = P_sRGB;
2588 :
2589 : /* The output will now be one or two 8-bit gray or gray+alpha
2590 : * channels. The more complex case arises when the input has alpha.
2591 : */
2592 : if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2593 : png_ptr->num_trans > 0) &&
2594 : (output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2595 : {
2596 : /* Both input and output have an alpha channel, so no background
2597 : * processing is required; just map the GA bytes to the right
2598 : * color-map entry.
2599 : */
2600 : expand_tRNS = 1;
2601 :
2602 : if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
2603 : png_error(png_ptr, "rgb[ga] color-map: too few entries");
2604 :
2605 : cmap_entries = (unsigned int)make_ga_colormap(display);
2606 : background_index = PNG_CMAP_GA_BACKGROUND;
2607 : output_processing = PNG_CMAP_GA;
2608 : }
2609 :
2610 : else
2611 : {
2612 : /* Either the input or the output has no alpha channel, so there
2613 : * will be no non-opaque pixels in the color-map; it will just be
2614 : * grayscale.
2615 : */
2616 : if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
2617 : png_error(png_ptr, "rgb[gray] color-map: too few entries");
2618 :
2619 : /* Ideally this code would use libpng to do the gamma correction,
2620 : * but if an input alpha channel is to be removed we will hit the
2621 : * libpng bug in gamma+compose+rgb-to-gray (the double gamma
2622 : * correction bug). Fix this by dropping the gamma correction in
2623 : * this case and doing it in the palette; this will result in
2624 : * duplicate palette entries, but that's better than the
2625 : * alternative of double gamma correction.
2626 : */
2627 : if ((png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2628 : png_ptr->num_trans > 0) &&
2629 : png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
2630 : {
2631 : cmap_entries = (unsigned int)make_gray_file_colormap(display);
2632 : data_encoding = P_FILE;
2633 : }
2634 :
2635 : else
2636 : cmap_entries = (unsigned int)make_gray_colormap(display);
2637 :
2638 : /* But if the input has alpha or transparency it must be removed
2639 : */
2640 : if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2641 : png_ptr->num_trans > 0)
2642 : {
2643 : png_color_16 c;
2644 : png_uint_32 gray = back_g;
2645 :
2646 : /* We need to ensure that the application background exists in
2647 : * the colormap and that completely transparent pixels map to
2648 : * it. Achieve this simply by ensuring that the entry
2649 : * selected for the background really is the background color.
2650 : */
2651 : if (data_encoding == P_FILE) /* from the fixup above */
2652 : {
2653 : /* The app supplied a gray which is in output_encoding, we
2654 : * need to convert it to a value of the input (P_FILE)
2655 : * encoding then set this palette entry to the required
2656 : * output encoding.
2657 : */
2658 : if (output_encoding == P_sRGB)
2659 : gray = png_sRGB_table[gray]; /* now P_LINEAR */
2660 :
2661 : gray = PNG_DIV257(png_gamma_16bit_correct(gray,
2662 : png_ptr->colorspace.gamma)); /* now P_FILE */
2663 :
2664 : /* And make sure the corresponding palette entry contains
2665 : * exactly the required sRGB value.
2666 : */
2667 : png_create_colormap_entry(display, gray, back_g, back_g,
2668 : back_g, 0/*unused*/, output_encoding);
2669 : }
2670 :
2671 : else if (output_encoding == P_LINEAR)
2672 : {
2673 : gray = PNG_sRGB_FROM_LINEAR(gray * 255);
2674 :
2675 : /* And make sure the corresponding palette entry matches.
2676 : */
2677 : png_create_colormap_entry(display, gray, back_g, back_g,
2678 : back_g, 0/*unused*/, P_LINEAR);
2679 : }
2680 :
2681 : /* The background passed to libpng, however, must be the
2682 : * output (normally sRGB) value.
2683 : */
2684 : c.index = 0; /*unused*/
2685 : c.gray = c.red = c.green = c.blue = (png_uint_16)gray;
2686 :
2687 : /* NOTE: the following is apparently a bug in libpng. Without
2688 : * it the transparent color recognition in
2689 : * png_set_background_fixed seems to go wrong.
2690 : */
2691 : expand_tRNS = 1;
2692 : png_set_background_fixed(png_ptr, &c,
2693 : PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2694 : 0/*gamma: not used*/);
2695 : }
2696 :
2697 : output_processing = PNG_CMAP_NONE;
2698 : }
2699 : }
2700 :
2701 : else /* output is color */
2702 : {
2703 : /* We could use png_quantize here so long as there is no transparent
2704 : * color or alpha; png_quantize ignores alpha. Easier overall just
2705 : * to do it once and using PNG_DIV51 on the 6x6x6 reduced RGB cube.
2706 : * Consequently we always want libpng to produce sRGB data.
2707 : */
2708 : data_encoding = P_sRGB;
2709 :
2710 : /* Is there any transparency or alpha? */
2711 : if (png_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
2712 : png_ptr->num_trans > 0)
2713 : {
2714 : /* Is there alpha in the output too? If so all four channels are
2715 : * processed into a special RGB cube with alpha support.
2716 : */
2717 : if ((output_format & PNG_FORMAT_FLAG_ALPHA) != 0)
2718 : {
2719 : png_uint_32 r;
2720 :
2721 : if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2722 : png_error(png_ptr, "rgb+alpha color-map: too few entries");
2723 :
2724 : cmap_entries = (unsigned int)make_rgb_colormap(display);
2725 :
2726 : /* Add a transparent entry. */
2727 : png_create_colormap_entry(display, cmap_entries, 255, 255,
2728 : 255, 0, P_sRGB);
2729 :
2730 : /* This is stored as the background index for the processing
2731 : * algorithm.
2732 : */
2733 : background_index = cmap_entries++;
2734 :
2735 : /* Add 27 r,g,b entries each with alpha 0.5. */
2736 : for (r=0; r<256; r = (r << 1) | 0x7f)
2737 : {
2738 : png_uint_32 g;
2739 :
2740 : for (g=0; g<256; g = (g << 1) | 0x7f)
2741 : {
2742 : png_uint_32 b;
2743 :
2744 : /* This generates components with the values 0, 127 and
2745 : * 255
2746 : */
2747 : for (b=0; b<256; b = (b << 1) | 0x7f)
2748 : png_create_colormap_entry(display, cmap_entries++,
2749 : r, g, b, 128, P_sRGB);
2750 : }
2751 : }
2752 :
2753 : expand_tRNS = 1;
2754 : output_processing = PNG_CMAP_RGB_ALPHA;
2755 : }
2756 :
2757 : else
2758 : {
2759 : /* Alpha/transparency must be removed. The background must
2760 : * exist in the color map (achieved by setting adding it after
2761 : * the 666 color-map). If the standard processing code will
2762 : * pick up this entry automatically that's all that is
2763 : * required; libpng can be called to do the background
2764 : * processing.
2765 : */
2766 : unsigned int sample_size =
2767 : PNG_IMAGE_SAMPLE_SIZE(output_format);
2768 : png_uint_32 r, g, b; /* sRGB background */
2769 :
2770 : if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
2771 : png_error(png_ptr, "rgb-alpha color-map: too few entries");
2772 :
2773 : cmap_entries = (unsigned int)make_rgb_colormap(display);
2774 :
2775 : png_create_colormap_entry(display, cmap_entries, back_r,
2776 : back_g, back_b, 0/*unused*/, output_encoding);
2777 :
2778 : if (output_encoding == P_LINEAR)
2779 : {
2780 : r = PNG_sRGB_FROM_LINEAR(back_r * 255);
2781 : g = PNG_sRGB_FROM_LINEAR(back_g * 255);
2782 : b = PNG_sRGB_FROM_LINEAR(back_b * 255);
2783 : }
2784 :
2785 : else
2786 : {
2787 : r = back_r;
2788 : g = back_g;
2789 : b = back_g;
2790 : }
2791 :
2792 : /* Compare the newly-created color-map entry with the one the
2793 : * PNG_CMAP_RGB algorithm will use. If the two entries don't
2794 : * match, add the new one and set this as the background
2795 : * index.
2796 : */
2797 : if (memcmp((png_const_bytep)display->colormap +
2798 : sample_size * cmap_entries,
2799 : (png_const_bytep)display->colormap +
2800 : sample_size * PNG_RGB_INDEX(r,g,b),
2801 : sample_size) != 0)
2802 : {
2803 : /* The background color must be added. */
2804 : background_index = cmap_entries++;
2805 :
2806 : /* Add 27 r,g,b entries each with created by composing with
2807 : * the background at alpha 0.5.
2808 : */
2809 : for (r=0; r<256; r = (r << 1) | 0x7f)
2810 : {
2811 : for (g=0; g<256; g = (g << 1) | 0x7f)
2812 : {
2813 : /* This generates components with the values 0, 127
2814 : * and 255
2815 : */
2816 : for (b=0; b<256; b = (b << 1) | 0x7f)
2817 : png_create_colormap_entry(display, cmap_entries++,
2818 : png_colormap_compose(display, r, P_sRGB, 128,
2819 : back_r, output_encoding),
2820 : png_colormap_compose(display, g, P_sRGB, 128,
2821 : back_g, output_encoding),
2822 : png_colormap_compose(display, b, P_sRGB, 128,
2823 : back_b, output_encoding),
2824 : 0/*unused*/, output_encoding);
2825 : }
2826 : }
2827 :
2828 : expand_tRNS = 1;
2829 : output_processing = PNG_CMAP_RGB_ALPHA;
2830 : }
2831 :
2832 : else /* background color is in the standard color-map */
2833 : {
2834 : png_color_16 c;
2835 :
2836 : c.index = 0; /*unused*/
2837 : c.red = (png_uint_16)back_r;
2838 : c.gray = c.green = (png_uint_16)back_g;
2839 : c.blue = (png_uint_16)back_b;
2840 :
2841 : png_set_background_fixed(png_ptr, &c,
2842 : PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
2843 : 0/*gamma: not used*/);
2844 :
2845 : output_processing = PNG_CMAP_RGB;
2846 : }
2847 : }
2848 : }
2849 :
2850 : else /* no alpha or transparency in the input */
2851 : {
2852 : /* Alpha in the output is irrelevant, simply map the opaque input
2853 : * pixels to the 6x6x6 color-map.
2854 : */
2855 : if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
2856 : png_error(png_ptr, "rgb color-map: too few entries");
2857 :
2858 : cmap_entries = (unsigned int)make_rgb_colormap(display);
2859 : output_processing = PNG_CMAP_RGB;
2860 : }
2861 : }
2862 : break;
2863 :
2864 : case PNG_COLOR_TYPE_PALETTE:
2865 : /* It's already got a color-map. It may be necessary to eliminate the
2866 : * tRNS entries though.
2867 : */
2868 : {
2869 : unsigned int num_trans = png_ptr->num_trans;
2870 : png_const_bytep trans = num_trans > 0 ? png_ptr->trans_alpha : NULL;
2871 : png_const_colorp colormap = png_ptr->palette;
2872 : const int do_background = trans != NULL &&
2873 : (output_format & PNG_FORMAT_FLAG_ALPHA) == 0;
2874 : unsigned int i;
2875 :
2876 : /* Just in case: */
2877 : if (trans == NULL)
2878 : num_trans = 0;
2879 :
2880 : output_processing = PNG_CMAP_NONE;
2881 : data_encoding = P_FILE; /* Don't change from color-map indices */
2882 : cmap_entries = (unsigned int)png_ptr->num_palette;
2883 : if (cmap_entries > 256)
2884 : cmap_entries = 256;
2885 :
2886 : if (cmap_entries > (unsigned int)image->colormap_entries)
2887 : png_error(png_ptr, "palette color-map: too few entries");
2888 :
2889 : for (i=0; i < cmap_entries; ++i)
2890 : {
2891 : if (do_background != 0 && i < num_trans && trans[i] < 255)
2892 : {
2893 : if (trans[i] == 0)
2894 : png_create_colormap_entry(display, i, back_r, back_g,
2895 : back_b, 0, output_encoding);
2896 :
2897 : else
2898 : {
2899 : /* Must compose the PNG file color in the color-map entry
2900 : * on the sRGB color in 'back'.
2901 : */
2902 : png_create_colormap_entry(display, i,
2903 : png_colormap_compose(display, colormap[i].red,
2904 : P_FILE, trans[i], back_r, output_encoding),
2905 : png_colormap_compose(display, colormap[i].green,
2906 : P_FILE, trans[i], back_g, output_encoding),
2907 : png_colormap_compose(display, colormap[i].blue,
2908 : P_FILE, trans[i], back_b, output_encoding),
2909 : output_encoding == P_LINEAR ? trans[i] * 257U :
2910 : trans[i],
2911 : output_encoding);
2912 : }
2913 : }
2914 :
2915 : else
2916 : png_create_colormap_entry(display, i, colormap[i].red,
2917 : colormap[i].green, colormap[i].blue,
2918 : i < num_trans ? trans[i] : 255U, P_FILE/*8-bit*/);
2919 : }
2920 :
2921 : /* The PNG data may have indices packed in fewer than 8 bits, it
2922 : * must be expanded if so.
2923 : */
2924 : if (png_ptr->bit_depth < 8)
2925 : png_set_packing(png_ptr);
2926 : }
2927 : break;
2928 :
2929 : default:
2930 : png_error(png_ptr, "invalid PNG color type");
2931 : /*NOT REACHED*/
2932 : }
2933 :
2934 : /* Now deal with the output processing */
2935 : if (expand_tRNS != 0 && png_ptr->num_trans > 0 &&
2936 : (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) == 0)
2937 : png_set_tRNS_to_alpha(png_ptr);
2938 :
2939 : switch (data_encoding)
2940 : {
2941 : case P_sRGB:
2942 : /* Change to 8-bit sRGB */
2943 : png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, PNG_GAMMA_sRGB);
2944 : /* FALL THROUGH */
2945 :
2946 : case P_FILE:
2947 : if (png_ptr->bit_depth > 8)
2948 : png_set_scale_16(png_ptr);
2949 : break;
2950 :
2951 : #ifdef __GNUC__
2952 : default:
2953 : png_error(png_ptr, "bad data option (internal error)");
2954 : #endif
2955 : }
2956 :
2957 : if (cmap_entries > 256 || cmap_entries > image->colormap_entries)
2958 : png_error(png_ptr, "color map overflow (BAD internal error)");
2959 :
2960 : image->colormap_entries = cmap_entries;
2961 :
2962 : /* Double check using the recorded background index */
2963 : switch (output_processing)
2964 : {
2965 : case PNG_CMAP_NONE:
2966 : if (background_index != PNG_CMAP_NONE_BACKGROUND)
2967 : goto bad_background;
2968 : break;
2969 :
2970 : case PNG_CMAP_GA:
2971 : if (background_index != PNG_CMAP_GA_BACKGROUND)
2972 : goto bad_background;
2973 : break;
2974 :
2975 : case PNG_CMAP_TRANS:
2976 : if (background_index >= cmap_entries ||
2977 : background_index != PNG_CMAP_TRANS_BACKGROUND)
2978 : goto bad_background;
2979 : break;
2980 :
2981 : case PNG_CMAP_RGB:
2982 : if (background_index != PNG_CMAP_RGB_BACKGROUND)
2983 : goto bad_background;
2984 : break;
2985 :
2986 : case PNG_CMAP_RGB_ALPHA:
2987 : if (background_index != PNG_CMAP_RGB_ALPHA_BACKGROUND)
2988 : goto bad_background;
2989 : break;
2990 :
2991 : default:
2992 : png_error(png_ptr, "bad processing option (internal error)");
2993 :
2994 : bad_background:
2995 : png_error(png_ptr, "bad background index (internal error)");
2996 : }
2997 :
2998 : display->colormap_processing = (int)output_processing;
2999 :
3000 : return 1/*ok*/;
3001 : }
3002 :
3003 : /* The final part of the color-map read called from png_image_finish_read. */
3004 : static int
3005 : png_image_read_and_map(png_voidp argument)
3006 : {
3007 : png_image_read_control *display = png_voidcast(png_image_read_control*,
3008 : argument);
3009 : png_imagep image = display->image;
3010 : png_structrp png_ptr = image->opaque->png_ptr;
3011 : int passes;
3012 :
3013 : /* Called when the libpng data must be transformed into the color-mapped
3014 : * form. There is a local row buffer in display->local and this routine must
3015 : * do the interlace handling.
3016 : */
3017 : switch (png_ptr->interlaced)
3018 : {
3019 : case PNG_INTERLACE_NONE:
3020 : passes = 1;
3021 : break;
3022 :
3023 : case PNG_INTERLACE_ADAM7:
3024 : passes = PNG_INTERLACE_ADAM7_PASSES;
3025 : break;
3026 :
3027 : default:
3028 : png_error(png_ptr, "unknown interlace type");
3029 : }
3030 :
3031 : {
3032 : png_uint_32 height = image->height;
3033 : png_uint_32 width = image->width;
3034 : int proc = display->colormap_processing;
3035 : png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3036 : ptrdiff_t step_row = display->row_bytes;
3037 : int pass;
3038 :
3039 : for (pass = 0; pass < passes; ++pass)
3040 : {
3041 : unsigned int startx, stepx, stepy;
3042 : png_uint_32 y;
3043 :
3044 : if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3045 : {
3046 : /* The row may be empty for a short image: */
3047 : if (PNG_PASS_COLS(width, pass) == 0)
3048 : continue;
3049 :
3050 : startx = PNG_PASS_START_COL(pass);
3051 : stepx = PNG_PASS_COL_OFFSET(pass);
3052 : y = PNG_PASS_START_ROW(pass);
3053 : stepy = PNG_PASS_ROW_OFFSET(pass);
3054 : }
3055 :
3056 : else
3057 : {
3058 : y = 0;
3059 : startx = 0;
3060 : stepx = stepy = 1;
3061 : }
3062 :
3063 : for (; y<height; y += stepy)
3064 : {
3065 : png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3066 : png_bytep outrow = first_row + y * step_row;
3067 : png_const_bytep end_row = outrow + width;
3068 :
3069 : /* Read read the libpng data into the temporary buffer. */
3070 : png_read_row(png_ptr, inrow, NULL);
3071 :
3072 : /* Now process the row according to the processing option, note
3073 : * that the caller verifies that the format of the libpng output
3074 : * data is as required.
3075 : */
3076 : outrow += startx;
3077 : switch (proc)
3078 : {
3079 : case PNG_CMAP_GA:
3080 : for (; outrow < end_row; outrow += stepx)
3081 : {
3082 : /* The data is always in the PNG order */
3083 : unsigned int gray = *inrow++;
3084 : unsigned int alpha = *inrow++;
3085 : unsigned int entry;
3086 :
3087 : /* NOTE: this code is copied as a comment in
3088 : * make_ga_colormap above. Please update the
3089 : * comment if you change this code!
3090 : */
3091 : if (alpha > 229) /* opaque */
3092 : {
3093 : entry = (231 * gray + 128) >> 8;
3094 : }
3095 : else if (alpha < 26) /* transparent */
3096 : {
3097 : entry = 231;
3098 : }
3099 : else /* partially opaque */
3100 : {
3101 : entry = 226 + 6 * PNG_DIV51(alpha) + PNG_DIV51(gray);
3102 : }
3103 :
3104 : *outrow = (png_byte)entry;
3105 : }
3106 : break;
3107 :
3108 : case PNG_CMAP_TRANS:
3109 : for (; outrow < end_row; outrow += stepx)
3110 : {
3111 : png_byte gray = *inrow++;
3112 : png_byte alpha = *inrow++;
3113 :
3114 : if (alpha == 0)
3115 : *outrow = PNG_CMAP_TRANS_BACKGROUND;
3116 :
3117 : else if (gray != PNG_CMAP_TRANS_BACKGROUND)
3118 : *outrow = gray;
3119 :
3120 : else
3121 : *outrow = (png_byte)(PNG_CMAP_TRANS_BACKGROUND+1);
3122 : }
3123 : break;
3124 :
3125 : case PNG_CMAP_RGB:
3126 : for (; outrow < end_row; outrow += stepx)
3127 : {
3128 : *outrow = PNG_RGB_INDEX(inrow[0], inrow[1], inrow[2]);
3129 : inrow += 3;
3130 : }
3131 : break;
3132 :
3133 : case PNG_CMAP_RGB_ALPHA:
3134 : for (; outrow < end_row; outrow += stepx)
3135 : {
3136 : unsigned int alpha = inrow[3];
3137 :
3138 : /* Because the alpha entries only hold alpha==0.5 values
3139 : * split the processing at alpha==0.25 (64) and 0.75
3140 : * (196).
3141 : */
3142 :
3143 : if (alpha >= 196)
3144 : *outrow = PNG_RGB_INDEX(inrow[0], inrow[1],
3145 : inrow[2]);
3146 :
3147 : else if (alpha < 64)
3148 : *outrow = PNG_CMAP_RGB_ALPHA_BACKGROUND;
3149 :
3150 : else
3151 : {
3152 : /* Likewise there are three entries for each of r, g
3153 : * and b. We could select the entry by popcount on
3154 : * the top two bits on those architectures that
3155 : * support it, this is what the code below does,
3156 : * crudely.
3157 : */
3158 : unsigned int back_i = PNG_CMAP_RGB_ALPHA_BACKGROUND+1;
3159 :
3160 : /* Here are how the values map:
3161 : *
3162 : * 0x00 .. 0x3f -> 0
3163 : * 0x40 .. 0xbf -> 1
3164 : * 0xc0 .. 0xff -> 2
3165 : *
3166 : * So, as above with the explicit alpha checks, the
3167 : * breakpoints are at 64 and 196.
3168 : */
3169 : if (inrow[0] & 0x80) back_i += 9; /* red */
3170 : if (inrow[0] & 0x40) back_i += 9;
3171 : if (inrow[0] & 0x80) back_i += 3; /* green */
3172 : if (inrow[0] & 0x40) back_i += 3;
3173 : if (inrow[0] & 0x80) back_i += 1; /* blue */
3174 : if (inrow[0] & 0x40) back_i += 1;
3175 :
3176 : *outrow = (png_byte)back_i;
3177 : }
3178 :
3179 : inrow += 4;
3180 : }
3181 : break;
3182 :
3183 : default:
3184 : break;
3185 : }
3186 : }
3187 : }
3188 : }
3189 :
3190 : return 1;
3191 : }
3192 :
3193 : static int
3194 : png_image_read_colormapped(png_voidp argument)
3195 : {
3196 : png_image_read_control *display = png_voidcast(png_image_read_control*,
3197 : argument);
3198 : png_imagep image = display->image;
3199 : png_controlp control = image->opaque;
3200 : png_structrp png_ptr = control->png_ptr;
3201 : png_inforp info_ptr = control->info_ptr;
3202 :
3203 : int passes = 0; /* As a flag */
3204 :
3205 : PNG_SKIP_CHUNKS(png_ptr);
3206 :
3207 : /* Update the 'info' structure and make sure the result is as required; first
3208 : * make sure to turn on the interlace handling if it will be required
3209 : * (because it can't be turned on *after* the call to png_read_update_info!)
3210 : */
3211 : if (display->colormap_processing == PNG_CMAP_NONE)
3212 : passes = png_set_interlace_handling(png_ptr);
3213 :
3214 : png_read_update_info(png_ptr, info_ptr);
3215 :
3216 : /* The expected output can be deduced from the colormap_processing option. */
3217 : switch (display->colormap_processing)
3218 : {
3219 : case PNG_CMAP_NONE:
3220 : /* Output must be one channel and one byte per pixel, the output
3221 : * encoding can be anything.
3222 : */
3223 : if ((info_ptr->color_type == PNG_COLOR_TYPE_PALETTE ||
3224 : info_ptr->color_type == PNG_COLOR_TYPE_GRAY) &&
3225 : info_ptr->bit_depth == 8)
3226 : break;
3227 :
3228 : goto bad_output;
3229 :
3230 : case PNG_CMAP_TRANS:
3231 : case PNG_CMAP_GA:
3232 : /* Output must be two channels and the 'G' one must be sRGB, the latter
3233 : * can be checked with an exact number because it should have been set
3234 : * to this number above!
3235 : */
3236 : if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA &&
3237 : info_ptr->bit_depth == 8 &&
3238 : png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3239 : image->colormap_entries == 256)
3240 : break;
3241 :
3242 : goto bad_output;
3243 :
3244 : case PNG_CMAP_RGB:
3245 : /* Output must be 8-bit sRGB encoded RGB */
3246 : if (info_ptr->color_type == PNG_COLOR_TYPE_RGB &&
3247 : info_ptr->bit_depth == 8 &&
3248 : png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3249 : image->colormap_entries == 216)
3250 : break;
3251 :
3252 : goto bad_output;
3253 :
3254 : case PNG_CMAP_RGB_ALPHA:
3255 : /* Output must be 8-bit sRGB encoded RGBA */
3256 : if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
3257 : info_ptr->bit_depth == 8 &&
3258 : png_ptr->screen_gamma == PNG_GAMMA_sRGB &&
3259 : image->colormap_entries == 244 /* 216 + 1 + 27 */)
3260 : break;
3261 :
3262 : /* goto bad_output; */
3263 : /* FALL THROUGH */
3264 :
3265 : default:
3266 : bad_output:
3267 : png_error(png_ptr, "bad color-map processing (internal error)");
3268 : }
3269 :
3270 : /* Now read the rows. Do this here if it is possible to read directly into
3271 : * the output buffer, otherwise allocate a local row buffer of the maximum
3272 : * size libpng requires and call the relevant processing routine safely.
3273 : */
3274 : {
3275 : png_voidp first_row = display->buffer;
3276 : ptrdiff_t row_bytes = display->row_stride;
3277 :
3278 : /* The following expression is designed to work correctly whether it gives
3279 : * a signed or an unsigned result.
3280 : */
3281 : if (row_bytes < 0)
3282 : {
3283 : char *ptr = png_voidcast(char*, first_row);
3284 : ptr += (image->height-1) * (-row_bytes);
3285 : first_row = png_voidcast(png_voidp, ptr);
3286 : }
3287 :
3288 : display->first_row = first_row;
3289 : display->row_bytes = row_bytes;
3290 : }
3291 :
3292 : if (passes == 0)
3293 : {
3294 : int result;
3295 : png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
3296 :
3297 : display->local_row = row;
3298 : result = png_safe_execute(image, png_image_read_and_map, display);
3299 : display->local_row = NULL;
3300 : png_free(png_ptr, row);
3301 :
3302 : return result;
3303 : }
3304 :
3305 : else
3306 : {
3307 : png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
3308 :
3309 : while (--passes >= 0)
3310 : {
3311 : png_uint_32 y = image->height;
3312 : png_bytep row = png_voidcast(png_bytep, display->first_row);
3313 :
3314 : for (; y > 0; --y)
3315 : {
3316 : png_read_row(png_ptr, row, NULL);
3317 : row += row_bytes;
3318 : }
3319 : }
3320 :
3321 : return 1;
3322 : }
3323 : }
3324 :
3325 : /* Just the row reading part of png_image_read. */
3326 : static int
3327 : png_image_read_composite(png_voidp argument)
3328 : {
3329 : png_image_read_control *display = png_voidcast(png_image_read_control*,
3330 : argument);
3331 : png_imagep image = display->image;
3332 : png_structrp png_ptr = image->opaque->png_ptr;
3333 : int passes;
3334 :
3335 : switch (png_ptr->interlaced)
3336 : {
3337 : case PNG_INTERLACE_NONE:
3338 : passes = 1;
3339 : break;
3340 :
3341 : case PNG_INTERLACE_ADAM7:
3342 : passes = PNG_INTERLACE_ADAM7_PASSES;
3343 : break;
3344 :
3345 : default:
3346 : png_error(png_ptr, "unknown interlace type");
3347 : }
3348 :
3349 : {
3350 : png_uint_32 height = image->height;
3351 : png_uint_32 width = image->width;
3352 : ptrdiff_t step_row = display->row_bytes;
3353 : unsigned int channels =
3354 : (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
3355 : int pass;
3356 :
3357 : for (pass = 0; pass < passes; ++pass)
3358 : {
3359 : unsigned int startx, stepx, stepy;
3360 : png_uint_32 y;
3361 :
3362 : if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3363 : {
3364 : /* The row may be empty for a short image: */
3365 : if (PNG_PASS_COLS(width, pass) == 0)
3366 : continue;
3367 :
3368 : startx = PNG_PASS_START_COL(pass) * channels;
3369 : stepx = PNG_PASS_COL_OFFSET(pass) * channels;
3370 : y = PNG_PASS_START_ROW(pass);
3371 : stepy = PNG_PASS_ROW_OFFSET(pass);
3372 : }
3373 :
3374 : else
3375 : {
3376 : y = 0;
3377 : startx = 0;
3378 : stepx = channels;
3379 : stepy = 1;
3380 : }
3381 :
3382 : for (; y<height; y += stepy)
3383 : {
3384 : png_bytep inrow = png_voidcast(png_bytep, display->local_row);
3385 : png_bytep outrow;
3386 : png_const_bytep end_row;
3387 :
3388 : /* Read the row, which is packed: */
3389 : png_read_row(png_ptr, inrow, NULL);
3390 :
3391 : outrow = png_voidcast(png_bytep, display->first_row);
3392 : outrow += y * step_row;
3393 : end_row = outrow + width * channels;
3394 :
3395 : /* Now do the composition on each pixel in this row. */
3396 : outrow += startx;
3397 : for (; outrow < end_row; outrow += stepx)
3398 : {
3399 : png_byte alpha = inrow[channels];
3400 :
3401 : if (alpha > 0) /* else no change to the output */
3402 : {
3403 : unsigned int c;
3404 :
3405 : for (c=0; c<channels; ++c)
3406 : {
3407 : png_uint_32 component = inrow[c];
3408 :
3409 : if (alpha < 255) /* else just use component */
3410 : {
3411 : /* This is PNG_OPTIMIZED_ALPHA, the component value
3412 : * is a linear 8-bit value. Combine this with the
3413 : * current outrow[c] value which is sRGB encoded.
3414 : * Arithmetic here is 16-bits to preserve the output
3415 : * values correctly.
3416 : */
3417 : component *= 257*255; /* =65535 */
3418 : component += (255-alpha)*png_sRGB_table[outrow[c]];
3419 :
3420 : /* So 'component' is scaled by 255*65535 and is
3421 : * therefore appropriate for the sRGB to linear
3422 : * conversion table.
3423 : */
3424 : component = PNG_sRGB_FROM_LINEAR(component);
3425 : }
3426 :
3427 : outrow[c] = (png_byte)component;
3428 : }
3429 : }
3430 :
3431 : inrow += channels+1; /* components and alpha channel */
3432 : }
3433 : }
3434 : }
3435 : }
3436 :
3437 : return 1;
3438 : }
3439 :
3440 : /* The do_local_background case; called when all the following transforms are to
3441 : * be done:
3442 : *
3443 : * PNG_RGB_TO_GRAY
3444 : * PNG_COMPOSITE
3445 : * PNG_GAMMA
3446 : *
3447 : * This is a work-around for the fact that both the PNG_RGB_TO_GRAY and
3448 : * PNG_COMPOSITE code performs gamma correction, so we get double gamma
3449 : * correction. The fix-up is to prevent the PNG_COMPOSITE operation from
3450 : * happening inside libpng, so this routine sees an 8 or 16-bit gray+alpha
3451 : * row and handles the removal or pre-multiplication of the alpha channel.
3452 : */
3453 : static int
3454 : png_image_read_background(png_voidp argument)
3455 : {
3456 : png_image_read_control *display = png_voidcast(png_image_read_control*,
3457 : argument);
3458 : png_imagep image = display->image;
3459 : png_structrp png_ptr = image->opaque->png_ptr;
3460 : png_inforp info_ptr = image->opaque->info_ptr;
3461 : png_uint_32 height = image->height;
3462 : png_uint_32 width = image->width;
3463 : int pass, passes;
3464 :
3465 : /* Double check the convoluted logic below. We expect to get here with
3466 : * libpng doing rgb to gray and gamma correction but background processing
3467 : * left to the png_image_read_background function. The rows libpng produce
3468 : * might be 8 or 16-bit but should always have two channels; gray plus alpha.
3469 : */
3470 : if ((png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
3471 : png_error(png_ptr, "lost rgb to gray");
3472 :
3473 : if ((png_ptr->transformations & PNG_COMPOSE) != 0)
3474 : png_error(png_ptr, "unexpected compose");
3475 :
3476 : if (png_get_channels(png_ptr, info_ptr) != 2)
3477 : png_error(png_ptr, "lost/gained channels");
3478 :
3479 : /* Expect the 8-bit case to always remove the alpha channel */
3480 : if ((image->format & PNG_FORMAT_FLAG_LINEAR) == 0 &&
3481 : (image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
3482 : png_error(png_ptr, "unexpected 8-bit transformation");
3483 :
3484 : switch (png_ptr->interlaced)
3485 : {
3486 : case PNG_INTERLACE_NONE:
3487 : passes = 1;
3488 : break;
3489 :
3490 : case PNG_INTERLACE_ADAM7:
3491 : passes = PNG_INTERLACE_ADAM7_PASSES;
3492 : break;
3493 :
3494 : default:
3495 : png_error(png_ptr, "unknown interlace type");
3496 : }
3497 :
3498 : /* Use direct access to info_ptr here because otherwise the simplified API
3499 : * would require PNG_EASY_ACCESS_SUPPORTED (just for this.) Note this is
3500 : * checking the value after libpng expansions, not the original value in the
3501 : * PNG.
3502 : */
3503 : switch (info_ptr->bit_depth)
3504 : {
3505 : case 8:
3506 : /* 8-bit sRGB gray values with an alpha channel; the alpha channel is
3507 : * to be removed by composing on a background: either the row if
3508 : * display->background is NULL or display->background->green if not.
3509 : * Unlike the code above ALPHA_OPTIMIZED has *not* been done.
3510 : */
3511 : {
3512 : png_bytep first_row = png_voidcast(png_bytep, display->first_row);
3513 : ptrdiff_t step_row = display->row_bytes;
3514 :
3515 : for (pass = 0; pass < passes; ++pass)
3516 : {
3517 : png_bytep row = png_voidcast(png_bytep, display->first_row);
3518 : unsigned int startx, stepx, stepy;
3519 : png_uint_32 y;
3520 :
3521 : if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3522 : {
3523 : /* The row may be empty for a short image: */
3524 : if (PNG_PASS_COLS(width, pass) == 0)
3525 : continue;
3526 :
3527 : startx = PNG_PASS_START_COL(pass);
3528 : stepx = PNG_PASS_COL_OFFSET(pass);
3529 : y = PNG_PASS_START_ROW(pass);
3530 : stepy = PNG_PASS_ROW_OFFSET(pass);
3531 : }
3532 :
3533 : else
3534 : {
3535 : y = 0;
3536 : startx = 0;
3537 : stepx = stepy = 1;
3538 : }
3539 :
3540 : if (display->background == NULL)
3541 : {
3542 : for (; y<height; y += stepy)
3543 : {
3544 : png_bytep inrow = png_voidcast(png_bytep,
3545 : display->local_row);
3546 : png_bytep outrow = first_row + y * step_row;
3547 : png_const_bytep end_row = outrow + width;
3548 :
3549 : /* Read the row, which is packed: */
3550 : png_read_row(png_ptr, inrow, NULL);
3551 :
3552 : /* Now do the composition on each pixel in this row. */
3553 : outrow += startx;
3554 : for (; outrow < end_row; outrow += stepx)
3555 : {
3556 : png_byte alpha = inrow[1];
3557 :
3558 : if (alpha > 0) /* else no change to the output */
3559 : {
3560 : png_uint_32 component = inrow[0];
3561 :
3562 : if (alpha < 255) /* else just use component */
3563 : {
3564 : /* Since PNG_OPTIMIZED_ALPHA was not set it is
3565 : * necessary to invert the sRGB transfer
3566 : * function and multiply the alpha out.
3567 : */
3568 : component = png_sRGB_table[component] * alpha;
3569 : component += png_sRGB_table[outrow[0]] *
3570 : (255-alpha);
3571 : component = PNG_sRGB_FROM_LINEAR(component);
3572 : }
3573 :
3574 : outrow[0] = (png_byte)component;
3575 : }
3576 :
3577 : inrow += 2; /* gray and alpha channel */
3578 : }
3579 : }
3580 : }
3581 :
3582 : else /* constant background value */
3583 : {
3584 : png_byte background8 = display->background->green;
3585 : png_uint_16 background = png_sRGB_table[background8];
3586 :
3587 : for (; y<height; y += stepy)
3588 : {
3589 : png_bytep inrow = png_voidcast(png_bytep,
3590 : display->local_row);
3591 : png_bytep outrow = first_row + y * step_row;
3592 : png_const_bytep end_row = outrow + width;
3593 :
3594 : /* Read the row, which is packed: */
3595 : png_read_row(png_ptr, inrow, NULL);
3596 :
3597 : /* Now do the composition on each pixel in this row. */
3598 : outrow += startx;
3599 : for (; outrow < end_row; outrow += stepx)
3600 : {
3601 : png_byte alpha = inrow[1];
3602 :
3603 : if (alpha > 0) /* else use background */
3604 : {
3605 : png_uint_32 component = inrow[0];
3606 :
3607 : if (alpha < 255) /* else just use component */
3608 : {
3609 : component = png_sRGB_table[component] * alpha;
3610 : component += background * (255-alpha);
3611 : component = PNG_sRGB_FROM_LINEAR(component);
3612 : }
3613 :
3614 : outrow[0] = (png_byte)component;
3615 : }
3616 :
3617 : else
3618 : outrow[0] = background8;
3619 :
3620 : inrow += 2; /* gray and alpha channel */
3621 : }
3622 :
3623 : row += display->row_bytes;
3624 : }
3625 : }
3626 : }
3627 : }
3628 : break;
3629 :
3630 : case 16:
3631 : /* 16-bit linear with pre-multiplied alpha; the pre-multiplication must
3632 : * still be done and, maybe, the alpha channel removed. This code also
3633 : * handles the alpha-first option.
3634 : */
3635 : {
3636 : png_uint_16p first_row = png_voidcast(png_uint_16p,
3637 : display->first_row);
3638 : /* The division by two is safe because the caller passed in a
3639 : * stride which was multiplied by 2 (below) to get row_bytes.
3640 : */
3641 : ptrdiff_t step_row = display->row_bytes / 2;
3642 : unsigned int preserve_alpha = (image->format &
3643 : PNG_FORMAT_FLAG_ALPHA) != 0;
3644 : unsigned int outchannels = 1U+preserve_alpha;
3645 : int swap_alpha = 0;
3646 :
3647 : # ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
3648 : if (preserve_alpha != 0 &&
3649 : (image->format & PNG_FORMAT_FLAG_AFIRST) != 0)
3650 : swap_alpha = 1;
3651 : # endif
3652 :
3653 : for (pass = 0; pass < passes; ++pass)
3654 : {
3655 : unsigned int startx, stepx, stepy;
3656 : png_uint_32 y;
3657 :
3658 : /* The 'x' start and step are adjusted to output components here.
3659 : */
3660 : if (png_ptr->interlaced == PNG_INTERLACE_ADAM7)
3661 : {
3662 : /* The row may be empty for a short image: */
3663 : if (PNG_PASS_COLS(width, pass) == 0)
3664 : continue;
3665 :
3666 : startx = PNG_PASS_START_COL(pass) * outchannels;
3667 : stepx = PNG_PASS_COL_OFFSET(pass) * outchannels;
3668 : y = PNG_PASS_START_ROW(pass);
3669 : stepy = PNG_PASS_ROW_OFFSET(pass);
3670 : }
3671 :
3672 : else
3673 : {
3674 : y = 0;
3675 : startx = 0;
3676 : stepx = outchannels;
3677 : stepy = 1;
3678 : }
3679 :
3680 : for (; y<height; y += stepy)
3681 : {
3682 : png_const_uint_16p inrow;
3683 : png_uint_16p outrow = first_row + y*step_row;
3684 : png_uint_16p end_row = outrow + width * outchannels;
3685 :
3686 : /* Read the row, which is packed: */
3687 : png_read_row(png_ptr, png_voidcast(png_bytep,
3688 : display->local_row), NULL);
3689 : inrow = png_voidcast(png_const_uint_16p, display->local_row);
3690 :
3691 : /* Now do the pre-multiplication on each pixel in this row.
3692 : */
3693 : outrow += startx;
3694 : for (; outrow < end_row; outrow += stepx)
3695 : {
3696 : png_uint_32 component = inrow[0];
3697 : png_uint_16 alpha = inrow[1];
3698 :
3699 : if (alpha > 0) /* else 0 */
3700 : {
3701 : if (alpha < 65535) /* else just use component */
3702 : {
3703 : component *= alpha;
3704 : component += 32767;
3705 : component /= 65535;
3706 : }
3707 : }
3708 :
3709 : else
3710 : component = 0;
3711 :
3712 : outrow[swap_alpha] = (png_uint_16)component;
3713 : if (preserve_alpha != 0)
3714 : outrow[1 ^ swap_alpha] = alpha;
3715 :
3716 : inrow += 2; /* components and alpha channel */
3717 : }
3718 : }
3719 : }
3720 : }
3721 : break;
3722 :
3723 : #ifdef __GNUC__
3724 : default:
3725 : png_error(png_ptr, "unexpected bit depth");
3726 : #endif
3727 : }
3728 :
3729 : return 1;
3730 : }
3731 :
3732 : /* The guts of png_image_finish_read as a png_safe_execute callback. */
3733 : static int
3734 : png_image_read_direct(png_voidp argument)
3735 : {
3736 : png_image_read_control *display = png_voidcast(png_image_read_control*,
3737 : argument);
3738 : png_imagep image = display->image;
3739 : png_structrp png_ptr = image->opaque->png_ptr;
3740 : png_inforp info_ptr = image->opaque->info_ptr;
3741 :
3742 : png_uint_32 format = image->format;
3743 : int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
3744 : int do_local_compose = 0;
3745 : int do_local_background = 0; /* to avoid double gamma correction bug */
3746 : int passes = 0;
3747 :
3748 : /* Add transforms to ensure the correct output format is produced then check
3749 : * that the required implementation support is there. Always expand; always
3750 : * need 8 bits minimum, no palette and expanded tRNS.
3751 : */
3752 : png_set_expand(png_ptr);
3753 :
3754 : /* Now check the format to see if it was modified. */
3755 : {
3756 : png_uint_32 base_format = png_image_format(png_ptr) &
3757 : ~PNG_FORMAT_FLAG_COLORMAP /* removed by png_set_expand */;
3758 : png_uint_32 change = format ^ base_format;
3759 : png_fixed_point output_gamma;
3760 : int mode; /* alpha mode */
3761 :
3762 : /* Do this first so that we have a record if rgb to gray is happening. */
3763 : if ((change & PNG_FORMAT_FLAG_COLOR) != 0)
3764 : {
3765 : /* gray<->color transformation required. */
3766 : if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3767 : png_set_gray_to_rgb(png_ptr);
3768 :
3769 : else
3770 : {
3771 : /* libpng can't do both rgb to gray and
3772 : * background/pre-multiplication if there is also significant gamma
3773 : * correction, because both operations require linear colors and
3774 : * the code only supports one transform doing the gamma correction.
3775 : * Handle this by doing the pre-multiplication or background
3776 : * operation in this code, if necessary.
3777 : *
3778 : * TODO: fix this by rewriting pngrtran.c (!)
3779 : *
3780 : * For the moment (given that fixing this in pngrtran.c is an
3781 : * enormous change) 'do_local_background' is used to indicate that
3782 : * the problem exists.
3783 : */
3784 : if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3785 : do_local_background = 1/*maybe*/;
3786 :
3787 : png_set_rgb_to_gray_fixed(png_ptr, PNG_ERROR_ACTION_NONE,
3788 : PNG_RGB_TO_GRAY_DEFAULT, PNG_RGB_TO_GRAY_DEFAULT);
3789 : }
3790 :
3791 : change &= ~PNG_FORMAT_FLAG_COLOR;
3792 : }
3793 :
3794 : /* Set the gamma appropriately, linear for 16-bit input, sRGB otherwise.
3795 : */
3796 : {
3797 : png_fixed_point input_gamma_default;
3798 :
3799 : if ((base_format & PNG_FORMAT_FLAG_LINEAR) != 0 &&
3800 : (image->flags & PNG_IMAGE_FLAG_16BIT_sRGB) == 0)
3801 : input_gamma_default = PNG_GAMMA_LINEAR;
3802 : else
3803 : input_gamma_default = PNG_DEFAULT_sRGB;
3804 :
3805 : /* Call png_set_alpha_mode to set the default for the input gamma; the
3806 : * output gamma is set by a second call below.
3807 : */
3808 : png_set_alpha_mode_fixed(png_ptr, PNG_ALPHA_PNG, input_gamma_default);
3809 : }
3810 :
3811 : if (linear != 0)
3812 : {
3813 : /* If there *is* an alpha channel in the input it must be multiplied
3814 : * out; use PNG_ALPHA_STANDARD, otherwise just use PNG_ALPHA_PNG.
3815 : */
3816 : if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3817 : mode = PNG_ALPHA_STANDARD; /* associated alpha */
3818 :
3819 : else
3820 : mode = PNG_ALPHA_PNG;
3821 :
3822 : output_gamma = PNG_GAMMA_LINEAR;
3823 : }
3824 :
3825 : else
3826 : {
3827 : mode = PNG_ALPHA_PNG;
3828 : output_gamma = PNG_DEFAULT_sRGB;
3829 : }
3830 :
3831 : /* If 'do_local_background' is set check for the presence of gamma
3832 : * correction; this is part of the work-round for the libpng bug
3833 : * described above.
3834 : *
3835 : * TODO: fix libpng and remove this.
3836 : */
3837 : if (do_local_background != 0)
3838 : {
3839 : png_fixed_point gtest;
3840 :
3841 : /* This is 'png_gamma_threshold' from pngrtran.c; the test used for
3842 : * gamma correction, the screen gamma hasn't been set on png_struct
3843 : * yet; it's set below. png_struct::gamma, however, is set to the
3844 : * final value.
3845 : */
3846 : if (png_muldiv(>est, output_gamma, png_ptr->colorspace.gamma,
3847 : PNG_FP_1) != 0 && png_gamma_significant(gtest) == 0)
3848 : do_local_background = 0;
3849 :
3850 : else if (mode == PNG_ALPHA_STANDARD)
3851 : {
3852 : do_local_background = 2/*required*/;
3853 : mode = PNG_ALPHA_PNG; /* prevent libpng doing it */
3854 : }
3855 :
3856 : /* else leave as 1 for the checks below */
3857 : }
3858 :
3859 : /* If the bit-depth changes then handle that here. */
3860 : if ((change & PNG_FORMAT_FLAG_LINEAR) != 0)
3861 : {
3862 : if (linear != 0 /*16-bit output*/)
3863 : png_set_expand_16(png_ptr);
3864 :
3865 : else /* 8-bit output */
3866 : png_set_scale_16(png_ptr);
3867 :
3868 : change &= ~PNG_FORMAT_FLAG_LINEAR;
3869 : }
3870 :
3871 : /* Now the background/alpha channel changes. */
3872 : if ((change & PNG_FORMAT_FLAG_ALPHA) != 0)
3873 : {
3874 : /* Removing an alpha channel requires composition for the 8-bit
3875 : * formats; for the 16-bit it is already done, above, by the
3876 : * pre-multiplication and the channel just needs to be stripped.
3877 : */
3878 : if ((base_format & PNG_FORMAT_FLAG_ALPHA) != 0)
3879 : {
3880 : /* If RGB->gray is happening the alpha channel must be left and the
3881 : * operation completed locally.
3882 : *
3883 : * TODO: fix libpng and remove this.
3884 : */
3885 : if (do_local_background != 0)
3886 : do_local_background = 2/*required*/;
3887 :
3888 : /* 16-bit output: just remove the channel */
3889 : else if (linear != 0) /* compose on black (well, pre-multiply) */
3890 : png_set_strip_alpha(png_ptr);
3891 :
3892 : /* 8-bit output: do an appropriate compose */
3893 : else if (display->background != NULL)
3894 : {
3895 : png_color_16 c;
3896 :
3897 : c.index = 0; /*unused*/
3898 : c.red = display->background->red;
3899 : c.green = display->background->green;
3900 : c.blue = display->background->blue;
3901 : c.gray = display->background->green;
3902 :
3903 : /* This is always an 8-bit sRGB value, using the 'green' channel
3904 : * for gray is much better than calculating the luminance here;
3905 : * we can get off-by-one errors in that calculation relative to
3906 : * the app expectations and that will show up in transparent
3907 : * pixels.
3908 : */
3909 : png_set_background_fixed(png_ptr, &c,
3910 : PNG_BACKGROUND_GAMMA_SCREEN, 0/*need_expand*/,
3911 : 0/*gamma: not used*/);
3912 : }
3913 :
3914 : else /* compose on row: implemented below. */
3915 : {
3916 : do_local_compose = 1;
3917 : /* This leaves the alpha channel in the output, so it has to be
3918 : * removed by the code below. Set the encoding to the 'OPTIMIZE'
3919 : * one so the code only has to hack on the pixels that require
3920 : * composition.
3921 : */
3922 : mode = PNG_ALPHA_OPTIMIZED;
3923 : }
3924 : }
3925 :
3926 : else /* output needs an alpha channel */
3927 : {
3928 : /* This is tricky because it happens before the swap operation has
3929 : * been accomplished; however, the swap does *not* swap the added
3930 : * alpha channel (weird API), so it must be added in the correct
3931 : * place.
3932 : */
3933 : png_uint_32 filler; /* opaque filler */
3934 : int where;
3935 :
3936 : if (linear != 0)
3937 : filler = 65535;
3938 :
3939 : else
3940 : filler = 255;
3941 :
3942 : #ifdef PNG_FORMAT_AFIRST_SUPPORTED
3943 : if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
3944 : {
3945 : where = PNG_FILLER_BEFORE;
3946 : change &= ~PNG_FORMAT_FLAG_AFIRST;
3947 : }
3948 :
3949 : else
3950 : #endif
3951 : where = PNG_FILLER_AFTER;
3952 :
3953 : png_set_add_alpha(png_ptr, filler, where);
3954 : }
3955 :
3956 : /* This stops the (irrelevant) call to swap_alpha below. */
3957 : change &= ~PNG_FORMAT_FLAG_ALPHA;
3958 : }
3959 :
3960 : /* Now set the alpha mode correctly; this is always done, even if there is
3961 : * no alpha channel in either the input or the output because it correctly
3962 : * sets the output gamma.
3963 : */
3964 : png_set_alpha_mode_fixed(png_ptr, mode, output_gamma);
3965 :
3966 : # ifdef PNG_FORMAT_BGR_SUPPORTED
3967 : if ((change & PNG_FORMAT_FLAG_BGR) != 0)
3968 : {
3969 : /* Check only the output format; PNG is never BGR; don't do this if
3970 : * the output is gray, but fix up the 'format' value in that case.
3971 : */
3972 : if ((format & PNG_FORMAT_FLAG_COLOR) != 0)
3973 : png_set_bgr(png_ptr);
3974 :
3975 : else
3976 : format &= ~PNG_FORMAT_FLAG_BGR;
3977 :
3978 : change &= ~PNG_FORMAT_FLAG_BGR;
3979 : }
3980 : # endif
3981 :
3982 : # ifdef PNG_FORMAT_AFIRST_SUPPORTED
3983 : if ((change & PNG_FORMAT_FLAG_AFIRST) != 0)
3984 : {
3985 : /* Only relevant if there is an alpha channel - it's particularly
3986 : * important to handle this correctly because do_local_compose may
3987 : * be set above and then libpng will keep the alpha channel for this
3988 : * code to remove.
3989 : */
3990 : if ((format & PNG_FORMAT_FLAG_ALPHA) != 0)
3991 : {
3992 : /* Disable this if doing a local background,
3993 : * TODO: remove this when local background is no longer required.
3994 : */
3995 : if (do_local_background != 2)
3996 : png_set_swap_alpha(png_ptr);
3997 : }
3998 :
3999 : else
4000 : format &= ~PNG_FORMAT_FLAG_AFIRST;
4001 :
4002 : change &= ~PNG_FORMAT_FLAG_AFIRST;
4003 : }
4004 : # endif
4005 :
4006 : /* If the *output* is 16-bit then we need to check for a byte-swap on this
4007 : * architecture.
4008 : */
4009 : if (linear != 0)
4010 : {
4011 : PNG_CONST png_uint_16 le = 0x0001;
4012 :
4013 : if ((*(png_const_bytep) & le) != 0)
4014 : png_set_swap(png_ptr);
4015 : }
4016 :
4017 : /* If change is not now 0 some transformation is missing - error out. */
4018 : if (change != 0)
4019 : png_error(png_ptr, "png_read_image: unsupported transformation");
4020 : }
4021 :
4022 : PNG_SKIP_CHUNKS(png_ptr);
4023 :
4024 : /* Update the 'info' structure and make sure the result is as required; first
4025 : * make sure to turn on the interlace handling if it will be required
4026 : * (because it can't be turned on *after* the call to png_read_update_info!)
4027 : *
4028 : * TODO: remove the do_local_background fixup below.
4029 : */
4030 : if (do_local_compose == 0 && do_local_background != 2)
4031 : passes = png_set_interlace_handling(png_ptr);
4032 :
4033 : png_read_update_info(png_ptr, info_ptr);
4034 :
4035 : {
4036 : png_uint_32 info_format = 0;
4037 :
4038 : if ((info_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
4039 : info_format |= PNG_FORMAT_FLAG_COLOR;
4040 :
4041 : if ((info_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0)
4042 : {
4043 : /* do_local_compose removes this channel below. */
4044 : if (do_local_compose == 0)
4045 : {
4046 : /* do_local_background does the same if required. */
4047 : if (do_local_background != 2 ||
4048 : (format & PNG_FORMAT_FLAG_ALPHA) != 0)
4049 : info_format |= PNG_FORMAT_FLAG_ALPHA;
4050 : }
4051 : }
4052 :
4053 : else if (do_local_compose != 0) /* internal error */
4054 : png_error(png_ptr, "png_image_read: alpha channel lost");
4055 :
4056 : if (info_ptr->bit_depth == 16)
4057 : info_format |= PNG_FORMAT_FLAG_LINEAR;
4058 :
4059 : #ifdef PNG_FORMAT_BGR_SUPPORTED
4060 : if ((png_ptr->transformations & PNG_BGR) != 0)
4061 : info_format |= PNG_FORMAT_FLAG_BGR;
4062 : #endif
4063 :
4064 : #ifdef PNG_FORMAT_AFIRST_SUPPORTED
4065 : if (do_local_background == 2)
4066 : {
4067 : if ((format & PNG_FORMAT_FLAG_AFIRST) != 0)
4068 : info_format |= PNG_FORMAT_FLAG_AFIRST;
4069 : }
4070 :
4071 : if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0 ||
4072 : ((png_ptr->transformations & PNG_ADD_ALPHA) != 0 &&
4073 : (png_ptr->flags & PNG_FLAG_FILLER_AFTER) == 0))
4074 : {
4075 : if (do_local_background == 2)
4076 : png_error(png_ptr, "unexpected alpha swap transformation");
4077 :
4078 : info_format |= PNG_FORMAT_FLAG_AFIRST;
4079 : }
4080 : # endif
4081 :
4082 : /* This is actually an internal error. */
4083 : if (info_format != format)
4084 : png_error(png_ptr, "png_read_image: invalid transformations");
4085 : }
4086 :
4087 : /* Now read the rows. If do_local_compose is set then it is necessary to use
4088 : * a local row buffer. The output will be GA, RGBA or BGRA and must be
4089 : * converted to G, RGB or BGR as appropriate. The 'local_row' member of the
4090 : * display acts as a flag.
4091 : */
4092 : {
4093 : png_voidp first_row = display->buffer;
4094 : ptrdiff_t row_bytes = display->row_stride;
4095 :
4096 : if (linear != 0)
4097 : row_bytes *= 2;
4098 :
4099 : /* The following expression is designed to work correctly whether it gives
4100 : * a signed or an unsigned result.
4101 : */
4102 : if (row_bytes < 0)
4103 : {
4104 : char *ptr = png_voidcast(char*, first_row);
4105 : ptr += (image->height-1) * (-row_bytes);
4106 : first_row = png_voidcast(png_voidp, ptr);
4107 : }
4108 :
4109 : display->first_row = first_row;
4110 : display->row_bytes = row_bytes;
4111 : }
4112 :
4113 : if (do_local_compose != 0)
4114 : {
4115 : int result;
4116 : png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4117 :
4118 : display->local_row = row;
4119 : result = png_safe_execute(image, png_image_read_composite, display);
4120 : display->local_row = NULL;
4121 : png_free(png_ptr, row);
4122 :
4123 : return result;
4124 : }
4125 :
4126 : else if (do_local_background == 2)
4127 : {
4128 : int result;
4129 : png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
4130 :
4131 : display->local_row = row;
4132 : result = png_safe_execute(image, png_image_read_background, display);
4133 : display->local_row = NULL;
4134 : png_free(png_ptr, row);
4135 :
4136 : return result;
4137 : }
4138 :
4139 : else
4140 : {
4141 : png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
4142 :
4143 : while (--passes >= 0)
4144 : {
4145 : png_uint_32 y = image->height;
4146 : png_bytep row = png_voidcast(png_bytep, display->first_row);
4147 :
4148 : for (; y > 0; --y)
4149 : {
4150 : png_read_row(png_ptr, row, NULL);
4151 : row += row_bytes;
4152 : }
4153 : }
4154 :
4155 : return 1;
4156 : }
4157 : }
4158 :
4159 : int PNGAPI
4160 : png_image_finish_read(png_imagep image, png_const_colorp background,
4161 : void *buffer, png_int_32 row_stride, void *colormap)
4162 : {
4163 : if (image != NULL && image->version == PNG_IMAGE_VERSION)
4164 : {
4165 : /* Check for row_stride overflow. This check is not performed on the
4166 : * original PNG format because it may not occur in the output PNG format
4167 : * and libpng deals with the issues of reading the original.
4168 : */
4169 : const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
4170 :
4171 : /* The following checks just the 'row_stride' calculation to ensure it
4172 : * fits in a signed 32-bit value. Because channels/components can be
4173 : * either 1 or 2 bytes in size the length of a row can still overflow 32
4174 : * bits; this is just to verify that the 'row_stride' argument can be
4175 : * represented.
4176 : */
4177 : if (image->width <= 0x7fffffffU/channels) /* no overflow */
4178 : {
4179 : png_uint_32 check;
4180 : const png_uint_32 png_row_stride = image->width * channels;
4181 :
4182 : if (row_stride == 0)
4183 : row_stride = (png_int_32)/*SAFE*/png_row_stride;
4184 :
4185 : if (row_stride < 0)
4186 : check = (png_uint_32)(-row_stride);
4187 :
4188 : else
4189 : check = (png_uint_32)row_stride;
4190 :
4191 : /* This verifies 'check', the absolute value of the actual stride
4192 : * passed in and detects overflow in the application calculation (i.e.
4193 : * if the app did actually pass in a non-zero 'row_stride'.
4194 : */
4195 : if (image->opaque != NULL && buffer != NULL && check >= png_row_stride)
4196 : {
4197 : /* Now check for overflow of the image buffer calculation; this
4198 : * limits the whole image size to 32 bits for API compatibility with
4199 : * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
4200 : *
4201 : * The PNG_IMAGE_BUFFER_SIZE macro is:
4202 : *
4203 : * (PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)*height*(row_stride))
4204 : *
4205 : * And the component size is always 1 or 2, so make sure that the
4206 : * number of *bytes* that the application is saying are available
4207 : * does actually fit into a 32-bit number.
4208 : *
4209 : * NOTE: this will be changed in 1.7 because PNG_IMAGE_BUFFER_SIZE
4210 : * will be changed to use png_alloc_size_t; bigger images can be
4211 : * accomodated on 64-bit systems.
4212 : */
4213 : if (image->height <=
4214 : 0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
4215 : {
4216 : if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
4217 : (image->colormap_entries > 0 && colormap != NULL))
4218 : {
4219 : int result;
4220 : png_image_read_control display;
4221 :
4222 : memset(&display, 0, (sizeof display));
4223 : display.image = image;
4224 : display.buffer = buffer;
4225 : display.row_stride = row_stride;
4226 : display.colormap = colormap;
4227 : display.background = background;
4228 : display.local_row = NULL;
4229 :
4230 : /* Choose the correct 'end' routine; for the color-map case
4231 : * all the setup has already been done.
4232 : */
4233 : if ((image->format & PNG_FORMAT_FLAG_COLORMAP) != 0)
4234 : result =
4235 : png_safe_execute(image,
4236 : png_image_read_colormap, &display) &&
4237 : png_safe_execute(image,
4238 : png_image_read_colormapped, &display);
4239 :
4240 : else
4241 : result =
4242 : png_safe_execute(image,
4243 : png_image_read_direct, &display);
4244 :
4245 : png_image_free(image);
4246 : return result;
4247 : }
4248 :
4249 : else
4250 : return png_image_error(image,
4251 : "png_image_finish_read[color-map]: no color-map");
4252 : }
4253 :
4254 : else
4255 : return png_image_error(image,
4256 : "png_image_finish_read: image too large");
4257 : }
4258 :
4259 : else
4260 : return png_image_error(image,
4261 : "png_image_finish_read: invalid argument");
4262 : }
4263 :
4264 : else
4265 : return png_image_error(image,
4266 : "png_image_finish_read: row_stride too large");
4267 : }
4268 :
4269 : else if (image != NULL)
4270 : return png_image_error(image,
4271 : "png_image_finish_read: damaged PNG_IMAGE_VERSION");
4272 :
4273 : return 0;
4274 : }
4275 :
4276 : #endif /* SIMPLIFIED_READ */
4277 : #endif /* READ */
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