1
2 /* pngwtran.c - transforms the data in a row for PNG writers
3 *
4 * Last changed in libpng 1.6.0 [February 14, 2013]
5 * Copyright (c) 1998-2013 Glenn Randers-Pehrson
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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 #include "pngpriv.h"
14
15 #ifdef PNG_WRITE_SUPPORTED
16
17 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
18 /* Transform the data according to the user's wishes. The order of
19 * transformations is significant.
20 */
21 void /* PRIVATE */
png_do_write_transformations(png_structrp png_ptr,png_row_infop row_info)22 png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
23 {
24 png_debug(1, "in png_do_write_transformations");
25
26 if (png_ptr == NULL)
27 return;
28
29 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
30 if (png_ptr->transformations & PNG_USER_TRANSFORM)
31 if (png_ptr->write_user_transform_fn != NULL)
32 (*(png_ptr->write_user_transform_fn)) /* User write transform
33 function */
34 (png_ptr, /* png_ptr */
35 row_info, /* row_info: */
36 /* png_uint_32 width; width of row */
37 /* png_size_t rowbytes; number of bytes in row */
38 /* png_byte color_type; color type of pixels */
39 /* png_byte bit_depth; bit depth of samples */
40 /* png_byte channels; number of channels (1-4) */
41 /* png_byte pixel_depth; bits per pixel (depth*channels) */
42 png_ptr->row_buf + 1); /* start of pixel data for row */
43 #endif
44
45 #ifdef PNG_WRITE_FILLER_SUPPORTED
46 if (png_ptr->transformations & PNG_FILLER)
47 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
48 !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
49 #endif
50
51 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
52 if (png_ptr->transformations & PNG_PACKSWAP)
53 png_do_packswap(row_info, png_ptr->row_buf + 1);
54 #endif
55
56 #ifdef PNG_WRITE_PACK_SUPPORTED
57 if (png_ptr->transformations & PNG_PACK)
58 png_do_pack(row_info, png_ptr->row_buf + 1,
59 (png_uint_32)png_ptr->bit_depth);
60 #endif
61
62 #ifdef PNG_WRITE_SWAP_SUPPORTED
63 if (png_ptr->transformations & PNG_SWAP_BYTES)
64 png_do_swap(row_info, png_ptr->row_buf + 1);
65 #endif
66
67 #ifdef PNG_WRITE_SHIFT_SUPPORTED
68 if (png_ptr->transformations & PNG_SHIFT)
69 png_do_shift(row_info, png_ptr->row_buf + 1,
70 &(png_ptr->shift));
71 #endif
72
73 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
74 if (png_ptr->transformations & PNG_SWAP_ALPHA)
75 png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
76 #endif
77
78 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
79 if (png_ptr->transformations & PNG_INVERT_ALPHA)
80 png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
81 #endif
82
83 #ifdef PNG_WRITE_BGR_SUPPORTED
84 if (png_ptr->transformations & PNG_BGR)
85 png_do_bgr(row_info, png_ptr->row_buf + 1);
86 #endif
87
88 #ifdef PNG_WRITE_INVERT_SUPPORTED
89 if (png_ptr->transformations & PNG_INVERT_MONO)
90 png_do_invert(row_info, png_ptr->row_buf + 1);
91 #endif
92 }
93
94 #ifdef PNG_WRITE_PACK_SUPPORTED
95 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
96 * row_info bit depth should be 8 (one pixel per byte). The channels
97 * should be 1 (this only happens on grayscale and paletted images).
98 */
99 void /* PRIVATE */
png_do_pack(png_row_infop row_info,png_bytep row,png_uint_32 bit_depth)100 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
101 {
102 png_debug(1, "in png_do_pack");
103
104 if (row_info->bit_depth == 8 &&
105 row_info->channels == 1)
106 {
107 switch ((int)bit_depth)
108 {
109 case 1:
110 {
111 png_bytep sp, dp;
112 int mask, v;
113 png_uint_32 i;
114 png_uint_32 row_width = row_info->width;
115
116 sp = row;
117 dp = row;
118 mask = 0x80;
119 v = 0;
120
121 for (i = 0; i < row_width; i++)
122 {
123 if (*sp != 0)
124 v |= mask;
125
126 sp++;
127
128 if (mask > 1)
129 mask >>= 1;
130
131 else
132 {
133 mask = 0x80;
134 *dp = (png_byte)v;
135 dp++;
136 v = 0;
137 }
138 }
139
140 if (mask != 0x80)
141 *dp = (png_byte)v;
142
143 break;
144 }
145
146 case 2:
147 {
148 png_bytep sp, dp;
149 int shift, v;
150 png_uint_32 i;
151 png_uint_32 row_width = row_info->width;
152
153 sp = row;
154 dp = row;
155 shift = 6;
156 v = 0;
157
158 for (i = 0; i < row_width; i++)
159 {
160 png_byte value;
161
162 value = (png_byte)(*sp & 0x03);
163 v |= (value << shift);
164
165 if (shift == 0)
166 {
167 shift = 6;
168 *dp = (png_byte)v;
169 dp++;
170 v = 0;
171 }
172
173 else
174 shift -= 2;
175
176 sp++;
177 }
178
179 if (shift != 6)
180 *dp = (png_byte)v;
181
182 break;
183 }
184
185 case 4:
186 {
187 png_bytep sp, dp;
188 int shift, v;
189 png_uint_32 i;
190 png_uint_32 row_width = row_info->width;
191
192 sp = row;
193 dp = row;
194 shift = 4;
195 v = 0;
196
197 for (i = 0; i < row_width; i++)
198 {
199 png_byte value;
200
201 value = (png_byte)(*sp & 0x0f);
202 v |= (value << shift);
203
204 if (shift == 0)
205 {
206 shift = 4;
207 *dp = (png_byte)v;
208 dp++;
209 v = 0;
210 }
211
212 else
213 shift -= 4;
214
215 sp++;
216 }
217
218 if (shift != 4)
219 *dp = (png_byte)v;
220
221 break;
222 }
223
224 default:
225 break;
226 }
227
228 row_info->bit_depth = (png_byte)bit_depth;
229 row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
230 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
231 row_info->width);
232 }
233 }
234 #endif
235
236 #ifdef PNG_WRITE_SHIFT_SUPPORTED
237 /* Shift pixel values to take advantage of whole range. Pass the
238 * true number of bits in bit_depth. The row should be packed
239 * according to row_info->bit_depth. Thus, if you had a row of
240 * bit depth 4, but the pixels only had values from 0 to 7, you
241 * would pass 3 as bit_depth, and this routine would translate the
242 * data to 0 to 15.
243 */
244 void /* PRIVATE */
png_do_shift(png_row_infop row_info,png_bytep row,png_const_color_8p bit_depth)245 png_do_shift(png_row_infop row_info, png_bytep row,
246 png_const_color_8p bit_depth)
247 {
248 png_debug(1, "in png_do_shift");
249
250 if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
251 {
252 int shift_start[4], shift_dec[4];
253 int channels = 0;
254
255 if (row_info->color_type & PNG_COLOR_MASK_COLOR)
256 {
257 shift_start[channels] = row_info->bit_depth - bit_depth->red;
258 shift_dec[channels] = bit_depth->red;
259 channels++;
260
261 shift_start[channels] = row_info->bit_depth - bit_depth->green;
262 shift_dec[channels] = bit_depth->green;
263 channels++;
264
265 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
266 shift_dec[channels] = bit_depth->blue;
267 channels++;
268 }
269
270 else
271 {
272 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
273 shift_dec[channels] = bit_depth->gray;
274 channels++;
275 }
276
277 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
278 {
279 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
280 shift_dec[channels] = bit_depth->alpha;
281 channels++;
282 }
283
284 /* With low row depths, could only be grayscale, so one channel */
285 if (row_info->bit_depth < 8)
286 {
287 png_bytep bp = row;
288 png_size_t i;
289 unsigned int mask;
290 png_size_t row_bytes = row_info->rowbytes;
291
292 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
293 mask = 0x55;
294
295 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
296 mask = 0x11;
297
298 else
299 mask = 0xff;
300
301 for (i = 0; i < row_bytes; i++, bp++)
302 {
303 int j;
304 unsigned int v, out;
305
306 v = *bp;
307 out = 0;
308
309 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
310 {
311 if (j > 0)
312 out |= v << j;
313
314 else
315 out |= (v >> (-j)) & mask;
316 }
317
318 *bp = (png_byte)(out & 0xff);
319 }
320 }
321
322 else if (row_info->bit_depth == 8)
323 {
324 png_bytep bp = row;
325 png_uint_32 i;
326 png_uint_32 istop = channels * row_info->width;
327
328 for (i = 0; i < istop; i++, bp++)
329 {
330
331 const unsigned int c = i%channels;
332 int j;
333 unsigned int v, out;
334
335 v = *bp;
336 out = 0;
337
338 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
339 {
340 if (j > 0)
341 out |= v << j;
342
343 else
344 out |= v >> (-j);
345 }
346
347 *bp = (png_byte)(out & 0xff);
348 }
349 }
350
351 else
352 {
353 png_bytep bp;
354 png_uint_32 i;
355 png_uint_32 istop = channels * row_info->width;
356
357 for (bp = row, i = 0; i < istop; i++)
358 {
359 const unsigned int c = i%channels;
360 int j;
361 unsigned int value, v;
362
363 v = png_get_uint_16(bp);
364 value = 0;
365
366 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
367 {
368 if (j > 0)
369 value |= v << j;
370
371 else
372 value |= v >> (-j);
373 }
374 *bp++ = (png_byte)((value >> 8) & 0xff);
375 *bp++ = (png_byte)(value & 0xff);
376 }
377 }
378 }
379 }
380 #endif
381
382 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
383 void /* PRIVATE */
png_do_write_swap_alpha(png_row_infop row_info,png_bytep row)384 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
385 {
386 png_debug(1, "in png_do_write_swap_alpha");
387
388 {
389 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
390 {
391 if (row_info->bit_depth == 8)
392 {
393 /* This converts from ARGB to RGBA */
394 png_bytep sp, dp;
395 png_uint_32 i;
396 png_uint_32 row_width = row_info->width;
397
398 for (i = 0, sp = dp = row; i < row_width; i++)
399 {
400 png_byte save = *(sp++);
401 *(dp++) = *(sp++);
402 *(dp++) = *(sp++);
403 *(dp++) = *(sp++);
404 *(dp++) = save;
405 }
406 }
407
408 #ifdef PNG_WRITE_16BIT_SUPPORTED
409 else
410 {
411 /* This converts from AARRGGBB to RRGGBBAA */
412 png_bytep sp, dp;
413 png_uint_32 i;
414 png_uint_32 row_width = row_info->width;
415
416 for (i = 0, sp = dp = row; i < row_width; i++)
417 {
418 png_byte save[2];
419 save[0] = *(sp++);
420 save[1] = *(sp++);
421 *(dp++) = *(sp++);
422 *(dp++) = *(sp++);
423 *(dp++) = *(sp++);
424 *(dp++) = *(sp++);
425 *(dp++) = *(sp++);
426 *(dp++) = *(sp++);
427 *(dp++) = save[0];
428 *(dp++) = save[1];
429 }
430 }
431 #endif /* PNG_WRITE_16BIT_SUPPORTED */
432 }
433
434 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
435 {
436 if (row_info->bit_depth == 8)
437 {
438 /* This converts from AG to GA */
439 png_bytep sp, dp;
440 png_uint_32 i;
441 png_uint_32 row_width = row_info->width;
442
443 for (i = 0, sp = dp = row; i < row_width; i++)
444 {
445 png_byte save = *(sp++);
446 *(dp++) = *(sp++);
447 *(dp++) = save;
448 }
449 }
450
451 #ifdef PNG_WRITE_16BIT_SUPPORTED
452 else
453 {
454 /* This converts from AAGG to GGAA */
455 png_bytep sp, dp;
456 png_uint_32 i;
457 png_uint_32 row_width = row_info->width;
458
459 for (i = 0, sp = dp = row; i < row_width; i++)
460 {
461 png_byte save[2];
462 save[0] = *(sp++);
463 save[1] = *(sp++);
464 *(dp++) = *(sp++);
465 *(dp++) = *(sp++);
466 *(dp++) = save[0];
467 *(dp++) = save[1];
468 }
469 }
470 #endif /* PNG_WRITE_16BIT_SUPPORTED */
471 }
472 }
473 }
474 #endif
475
476 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
477 void /* PRIVATE */
png_do_write_invert_alpha(png_row_infop row_info,png_bytep row)478 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
479 {
480 png_debug(1, "in png_do_write_invert_alpha");
481
482 {
483 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
484 {
485 if (row_info->bit_depth == 8)
486 {
487 /* This inverts the alpha channel in RGBA */
488 png_bytep sp, dp;
489 png_uint_32 i;
490 png_uint_32 row_width = row_info->width;
491
492 for (i = 0, sp = dp = row; i < row_width; i++)
493 {
494 /* Does nothing
495 *(dp++) = *(sp++);
496 *(dp++) = *(sp++);
497 *(dp++) = *(sp++);
498 */
499 sp+=3; dp = sp;
500 *(dp++) = (png_byte)(255 - *(sp++));
501 }
502 }
503
504 #ifdef PNG_WRITE_16BIT_SUPPORTED
505 else
506 {
507 /* This inverts the alpha channel in RRGGBBAA */
508 png_bytep sp, dp;
509 png_uint_32 i;
510 png_uint_32 row_width = row_info->width;
511
512 for (i = 0, sp = dp = row; i < row_width; i++)
513 {
514 /* Does nothing
515 *(dp++) = *(sp++);
516 *(dp++) = *(sp++);
517 *(dp++) = *(sp++);
518 *(dp++) = *(sp++);
519 *(dp++) = *(sp++);
520 *(dp++) = *(sp++);
521 */
522 sp+=6; dp = sp;
523 *(dp++) = (png_byte)(255 - *(sp++));
524 *(dp++) = (png_byte)(255 - *(sp++));
525 }
526 }
527 #endif /* PNG_WRITE_16BIT_SUPPORTED */
528 }
529
530 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
531 {
532 if (row_info->bit_depth == 8)
533 {
534 /* This inverts the alpha channel in GA */
535 png_bytep sp, dp;
536 png_uint_32 i;
537 png_uint_32 row_width = row_info->width;
538
539 for (i = 0, sp = dp = row; i < row_width; i++)
540 {
541 *(dp++) = *(sp++);
542 *(dp++) = (png_byte)(255 - *(sp++));
543 }
544 }
545
546 #ifdef PNG_WRITE_16BIT_SUPPORTED
547 else
548 {
549 /* This inverts the alpha channel in GGAA */
550 png_bytep sp, dp;
551 png_uint_32 i;
552 png_uint_32 row_width = row_info->width;
553
554 for (i = 0, sp = dp = row; i < row_width; i++)
555 {
556 /* Does nothing
557 *(dp++) = *(sp++);
558 *(dp++) = *(sp++);
559 */
560 sp+=2; dp = sp;
561 *(dp++) = (png_byte)(255 - *(sp++));
562 *(dp++) = (png_byte)(255 - *(sp++));
563 }
564 }
565 #endif /* PNG_WRITE_16BIT_SUPPORTED */
566 }
567 }
568 }
569 #endif
570 #endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
571
572 #ifdef PNG_MNG_FEATURES_SUPPORTED
573 /* Undoes intrapixel differencing */
574 void /* PRIVATE */
png_do_write_intrapixel(png_row_infop row_info,png_bytep row)575 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
576 {
577 png_debug(1, "in png_do_write_intrapixel");
578
579 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
580 {
581 int bytes_per_pixel;
582 png_uint_32 row_width = row_info->width;
583 if (row_info->bit_depth == 8)
584 {
585 png_bytep rp;
586 png_uint_32 i;
587
588 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
589 bytes_per_pixel = 3;
590
591 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
592 bytes_per_pixel = 4;
593
594 else
595 return;
596
597 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
598 {
599 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
600 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
601 }
602 }
603
604 #ifdef PNG_WRITE_16BIT_SUPPORTED
605 else if (row_info->bit_depth == 16)
606 {
607 png_bytep rp;
608 png_uint_32 i;
609
610 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
611 bytes_per_pixel = 6;
612
613 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
614 bytes_per_pixel = 8;
615
616 else
617 return;
618
619 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
620 {
621 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
622 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
623 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
624 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
625 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
626 *(rp ) = (png_byte)((red >> 8) & 0xff);
627 *(rp + 1) = (png_byte)(red & 0xff);
628 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
629 *(rp + 5) = (png_byte)(blue & 0xff);
630 }
631 }
632 #endif /* PNG_WRITE_16BIT_SUPPORTED */
633 }
634 }
635 #endif /* PNG_MNG_FEATURES_SUPPORTED */
636 #endif /* PNG_WRITE_SUPPORTED */
637