1
2 /* pngwtran.c - transforms the data in a row for PNG writers
3 *
4 * Last changed in libpng 1.5.6 [November 3, 2011]
5 * Copyright (c) 1998-2011 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
14 #include "pngpriv.h"
15
16 #ifdef PNG_WRITE_SUPPORTED
17
18 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
19 /* Transform the data according to the user's wishes. The order of
20 * transformations is significant.
21 */
22 void /* PRIVATE */
png_do_write_transformations(png_structp png_ptr,png_row_infop row_info)23 png_do_write_transformations(png_structp png_ptr, png_row_infop row_info)
24 {
25 png_debug(1, "in png_do_write_transformations");
26
27 if (png_ptr == NULL)
28 return;
29
30 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
31 if (png_ptr->transformations & PNG_USER_TRANSFORM)
32 if (png_ptr->write_user_transform_fn != NULL)
33 (*(png_ptr->write_user_transform_fn)) /* User write transform
34 function */
35 (png_ptr, /* png_ptr */
36 row_info, /* row_info: */
37 /* png_uint_32 width; width of row */
38 /* png_size_t rowbytes; number of bytes in row */
39 /* png_byte color_type; color type of pixels */
40 /* png_byte bit_depth; bit depth of samples */
41 /* png_byte channels; number of channels (1-4) */
42 /* png_byte pixel_depth; bits per pixel (depth*channels) */
43 png_ptr->row_buf + 1); /* start of pixel data for row */
44 #endif
45
46 #ifdef PNG_WRITE_FILLER_SUPPORTED
47 if (png_ptr->transformations & PNG_FILLER)
48 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
49 !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
50 #endif
51
52 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
53 if (png_ptr->transformations & PNG_PACKSWAP)
54 png_do_packswap(row_info, png_ptr->row_buf + 1);
55 #endif
56
57 #ifdef PNG_WRITE_PACK_SUPPORTED
58 if (png_ptr->transformations & PNG_PACK)
59 png_do_pack(row_info, png_ptr->row_buf + 1,
60 (png_uint_32)png_ptr->bit_depth);
61 #endif
62
63 #ifdef PNG_WRITE_SWAP_SUPPORTED
64 if (png_ptr->transformations & PNG_SWAP_BYTES)
65 png_do_swap(row_info, png_ptr->row_buf + 1);
66 #endif
67
68 #ifdef PNG_WRITE_SHIFT_SUPPORTED
69 if (png_ptr->transformations & PNG_SHIFT)
70 png_do_shift(row_info, png_ptr->row_buf + 1,
71 &(png_ptr->shift));
72 #endif
73
74 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
75 if (png_ptr->transformations & PNG_SWAP_ALPHA)
76 png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
77 #endif
78
79 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
80 if (png_ptr->transformations & PNG_INVERT_ALPHA)
81 png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
82 #endif
83
84 #ifdef PNG_WRITE_BGR_SUPPORTED
85 if (png_ptr->transformations & PNG_BGR)
86 png_do_bgr(row_info, png_ptr->row_buf + 1);
87 #endif
88
89 #ifdef PNG_WRITE_INVERT_SUPPORTED
90 if (png_ptr->transformations & PNG_INVERT_MONO)
91 png_do_invert(row_info, png_ptr->row_buf + 1);
92 #endif
93 }
94
95 #ifdef PNG_WRITE_PACK_SUPPORTED
96 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
97 * row_info bit depth should be 8 (one pixel per byte). The channels
98 * should be 1 (this only happens on grayscale and paletted images).
99 */
100 void /* PRIVATE */
png_do_pack(png_row_infop row_info,png_bytep row,png_uint_32 bit_depth)101 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
102 {
103 png_debug(1, "in png_do_pack");
104
105 if (row_info->bit_depth == 8 &&
106 row_info->channels == 1)
107 {
108 switch ((int)bit_depth)
109 {
110 case 1:
111 {
112 png_bytep sp, dp;
113 int mask, v;
114 png_uint_32 i;
115 png_uint_32 row_width = row_info->width;
116
117 sp = row;
118 dp = row;
119 mask = 0x80;
120 v = 0;
121
122 for (i = 0; i < row_width; i++)
123 {
124 if (*sp != 0)
125 v |= mask;
126
127 sp++;
128
129 if (mask > 1)
130 mask >>= 1;
131
132 else
133 {
134 mask = 0x80;
135 *dp = (png_byte)v;
136 dp++;
137 v = 0;
138 }
139 }
140
141 if (mask != 0x80)
142 *dp = (png_byte)v;
143
144 break;
145 }
146
147 case 2:
148 {
149 png_bytep sp, dp;
150 int shift, v;
151 png_uint_32 i;
152 png_uint_32 row_width = row_info->width;
153
154 sp = row;
155 dp = row;
156 shift = 6;
157 v = 0;
158
159 for (i = 0; i < row_width; i++)
160 {
161 png_byte value;
162
163 value = (png_byte)(*sp & 0x03);
164 v |= (value << shift);
165
166 if (shift == 0)
167 {
168 shift = 6;
169 *dp = (png_byte)v;
170 dp++;
171 v = 0;
172 }
173
174 else
175 shift -= 2;
176
177 sp++;
178 }
179
180 if (shift != 6)
181 *dp = (png_byte)v;
182
183 break;
184 }
185
186 case 4:
187 {
188 png_bytep sp, dp;
189 int shift, v;
190 png_uint_32 i;
191 png_uint_32 row_width = row_info->width;
192
193 sp = row;
194 dp = row;
195 shift = 4;
196 v = 0;
197
198 for (i = 0; i < row_width; i++)
199 {
200 png_byte value;
201
202 value = (png_byte)(*sp & 0x0f);
203 v |= (value << shift);
204
205 if (shift == 0)
206 {
207 shift = 4;
208 *dp = (png_byte)v;
209 dp++;
210 v = 0;
211 }
212
213 else
214 shift -= 4;
215
216 sp++;
217 }
218
219 if (shift != 4)
220 *dp = (png_byte)v;
221
222 break;
223 }
224
225 default:
226 break;
227 }
228
229 row_info->bit_depth = (png_byte)bit_depth;
230 row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
231 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
232 row_info->width);
233 }
234 }
235 #endif
236
237 #ifdef PNG_WRITE_SHIFT_SUPPORTED
238 /* Shift pixel values to take advantage of whole range. Pass the
239 * true number of bits in bit_depth. The row should be packed
240 * according to row_info->bit_depth. Thus, if you had a row of
241 * bit depth 4, but the pixels only had values from 0 to 7, you
242 * would pass 3 as bit_depth, and this routine would translate the
243 * data to 0 to 15.
244 */
245 void /* PRIVATE */
png_do_shift(png_row_infop row_info,png_bytep row,png_const_color_8p bit_depth)246 png_do_shift(png_row_infop row_info, png_bytep row,
247 png_const_color_8p bit_depth)
248 {
249 png_debug(1, "in png_do_shift");
250
251 if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
252 {
253 int shift_start[4], shift_dec[4];
254 int channels = 0;
255
256 if (row_info->color_type & PNG_COLOR_MASK_COLOR)
257 {
258 shift_start[channels] = row_info->bit_depth - bit_depth->red;
259 shift_dec[channels] = bit_depth->red;
260 channels++;
261
262 shift_start[channels] = row_info->bit_depth - bit_depth->green;
263 shift_dec[channels] = bit_depth->green;
264 channels++;
265
266 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
267 shift_dec[channels] = bit_depth->blue;
268 channels++;
269 }
270
271 else
272 {
273 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
274 shift_dec[channels] = bit_depth->gray;
275 channels++;
276 }
277
278 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
279 {
280 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
281 shift_dec[channels] = bit_depth->alpha;
282 channels++;
283 }
284
285 /* With low row depths, could only be grayscale, so one channel */
286 if (row_info->bit_depth < 8)
287 {
288 png_bytep bp = row;
289 png_size_t i;
290 png_byte mask;
291 png_size_t row_bytes = row_info->rowbytes;
292
293 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
294 mask = 0x55;
295
296 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
297 mask = 0x11;
298
299 else
300 mask = 0xff;
301
302 for (i = 0; i < row_bytes; i++, bp++)
303 {
304 png_uint_16 v;
305 int j;
306
307 v = *bp;
308 *bp = 0;
309
310 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
311 {
312 if (j > 0)
313 *bp |= (png_byte)((v << j) & 0xff);
314
315 else
316 *bp |= (png_byte)((v >> (-j)) & mask);
317 }
318 }
319 }
320
321 else if (row_info->bit_depth == 8)
322 {
323 png_bytep bp = row;
324 png_uint_32 i;
325 png_uint_32 istop = channels * row_info->width;
326
327 for (i = 0; i < istop; i++, bp++)
328 {
329
330 png_uint_16 v;
331 int j;
332 int c = (int)(i%channels);
333
334 v = *bp;
335 *bp = 0;
336
337 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
338 {
339 if (j > 0)
340 *bp |= (png_byte)((v << j) & 0xff);
341
342 else
343 *bp |= (png_byte)((v >> (-j)) & 0xff);
344 }
345 }
346 }
347
348 else
349 {
350 png_bytep bp;
351 png_uint_32 i;
352 png_uint_32 istop = channels * row_info->width;
353
354 for (bp = row, i = 0; i < istop; i++)
355 {
356 int c = (int)(i%channels);
357 png_uint_16 value, v;
358 int j;
359
360 v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
361 value = 0;
362
363 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
364 {
365 if (j > 0)
366 value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
367
368 else
369 value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
370 }
371 *bp++ = (png_byte)(value >> 8);
372 *bp++ = (png_byte)(value & 0xff);
373 }
374 }
375 }
376 }
377 #endif
378
379 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
380 void /* PRIVATE */
png_do_write_swap_alpha(png_row_infop row_info,png_bytep row)381 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
382 {
383 png_debug(1, "in png_do_write_swap_alpha");
384
385 {
386 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
387 {
388 if (row_info->bit_depth == 8)
389 {
390 /* This converts from ARGB to RGBA */
391 png_bytep sp, dp;
392 png_uint_32 i;
393 png_uint_32 row_width = row_info->width;
394
395 for (i = 0, sp = dp = row; i < row_width; i++)
396 {
397 png_byte save = *(sp++);
398 *(dp++) = *(sp++);
399 *(dp++) = *(sp++);
400 *(dp++) = *(sp++);
401 *(dp++) = save;
402 }
403 }
404
405 #ifdef PNG_WRITE_16BIT_SUPPORTED
406 else
407 {
408 /* This converts from AARRGGBB to RRGGBBAA */
409 png_bytep sp, dp;
410 png_uint_32 i;
411 png_uint_32 row_width = row_info->width;
412
413 for (i = 0, sp = dp = row; i < row_width; i++)
414 {
415 png_byte save[2];
416 save[0] = *(sp++);
417 save[1] = *(sp++);
418 *(dp++) = *(sp++);
419 *(dp++) = *(sp++);
420 *(dp++) = *(sp++);
421 *(dp++) = *(sp++);
422 *(dp++) = *(sp++);
423 *(dp++) = *(sp++);
424 *(dp++) = save[0];
425 *(dp++) = save[1];
426 }
427 }
428 #endif /* PNG_WRITE_16BIT_SUPPORTED */
429 }
430
431 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
432 {
433 if (row_info->bit_depth == 8)
434 {
435 /* This converts from AG to GA */
436 png_bytep sp, dp;
437 png_uint_32 i;
438 png_uint_32 row_width = row_info->width;
439
440 for (i = 0, sp = dp = row; i < row_width; i++)
441 {
442 png_byte save = *(sp++);
443 *(dp++) = *(sp++);
444 *(dp++) = save;
445 }
446 }
447
448 #ifdef PNG_WRITE_16BIT_SUPPORTED
449 else
450 {
451 /* This converts from AAGG to GGAA */
452 png_bytep sp, dp;
453 png_uint_32 i;
454 png_uint_32 row_width = row_info->width;
455
456 for (i = 0, sp = dp = row; i < row_width; i++)
457 {
458 png_byte save[2];
459 save[0] = *(sp++);
460 save[1] = *(sp++);
461 *(dp++) = *(sp++);
462 *(dp++) = *(sp++);
463 *(dp++) = save[0];
464 *(dp++) = save[1];
465 }
466 }
467 #endif /* PNG_WRITE_16BIT_SUPPORTED */
468 }
469 }
470 }
471 #endif
472
473 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
474 void /* PRIVATE */
png_do_write_invert_alpha(png_row_infop row_info,png_bytep row)475 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
476 {
477 png_debug(1, "in png_do_write_invert_alpha");
478
479 {
480 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
481 {
482 if (row_info->bit_depth == 8)
483 {
484 /* This inverts the alpha channel in RGBA */
485 png_bytep sp, dp;
486 png_uint_32 i;
487 png_uint_32 row_width = row_info->width;
488
489 for (i = 0, sp = dp = row; i < row_width; i++)
490 {
491 /* Does nothing
492 *(dp++) = *(sp++);
493 *(dp++) = *(sp++);
494 *(dp++) = *(sp++);
495 */
496 sp+=3; dp = sp;
497 *(dp++) = (png_byte)(255 - *(sp++));
498 }
499 }
500
501 #ifdef PNG_WRITE_16BIT_SUPPORTED
502 else
503 {
504 /* This inverts the alpha channel in RRGGBBAA */
505 png_bytep sp, dp;
506 png_uint_32 i;
507 png_uint_32 row_width = row_info->width;
508
509 for (i = 0, sp = dp = row; i < row_width; i++)
510 {
511 /* Does nothing
512 *(dp++) = *(sp++);
513 *(dp++) = *(sp++);
514 *(dp++) = *(sp++);
515 *(dp++) = *(sp++);
516 *(dp++) = *(sp++);
517 *(dp++) = *(sp++);
518 */
519 sp+=6; dp = sp;
520 *(dp++) = (png_byte)(255 - *(sp++));
521 *(dp++) = (png_byte)(255 - *(sp++));
522 }
523 }
524 #endif /* PNG_WRITE_16BIT_SUPPORTED */
525 }
526
527 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
528 {
529 if (row_info->bit_depth == 8)
530 {
531 /* This inverts the alpha channel in GA */
532 png_bytep sp, dp;
533 png_uint_32 i;
534 png_uint_32 row_width = row_info->width;
535
536 for (i = 0, sp = dp = row; i < row_width; i++)
537 {
538 *(dp++) = *(sp++);
539 *(dp++) = (png_byte)(255 - *(sp++));
540 }
541 }
542
543 #ifdef PNG_WRITE_16BIT_SUPPORTED
544 else
545 {
546 /* This inverts the alpha channel in GGAA */
547 png_bytep sp, dp;
548 png_uint_32 i;
549 png_uint_32 row_width = row_info->width;
550
551 for (i = 0, sp = dp = row; i < row_width; i++)
552 {
553 /* Does nothing
554 *(dp++) = *(sp++);
555 *(dp++) = *(sp++);
556 */
557 sp+=2; dp = sp;
558 *(dp++) = (png_byte)(255 - *(sp++));
559 *(dp++) = (png_byte)(255 - *(sp++));
560 }
561 }
562 #endif /* PNG_WRITE_16BIT_SUPPORTED */
563 }
564 }
565 }
566 #endif
567 #endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
568
569 #ifdef PNG_MNG_FEATURES_SUPPORTED
570 /* Undoes intrapixel differencing */
571 void /* PRIVATE */
png_do_write_intrapixel(png_row_infop row_info,png_bytep row)572 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
573 {
574 png_debug(1, "in png_do_write_intrapixel");
575
576 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
577 {
578 int bytes_per_pixel;
579 png_uint_32 row_width = row_info->width;
580 if (row_info->bit_depth == 8)
581 {
582 png_bytep rp;
583 png_uint_32 i;
584
585 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
586 bytes_per_pixel = 3;
587
588 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
589 bytes_per_pixel = 4;
590
591 else
592 return;
593
594 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
595 {
596 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
597 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
598 }
599 }
600
601 #ifdef PNG_WRITE_16BIT_SUPPORTED
602 else if (row_info->bit_depth == 16)
603 {
604 png_bytep rp;
605 png_uint_32 i;
606
607 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
608 bytes_per_pixel = 6;
609
610 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
611 bytes_per_pixel = 8;
612
613 else
614 return;
615
616 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
617 {
618 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
619 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
620 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
621 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
622 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
623 *(rp ) = (png_byte)((red >> 8) & 0xff);
624 *(rp + 1) = (png_byte)(red & 0xff);
625 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
626 *(rp + 5) = (png_byte)(blue & 0xff);
627 }
628 }
629 #endif /* PNG_WRITE_16BIT_SUPPORTED */
630 }
631 }
632 #endif /* PNG_MNG_FEATURES_SUPPORTED */
633 #endif /* PNG_WRITE_SUPPORTED */
634