]> git.saurik.com Git - wxWidgets.git/blame - src/png/pngwtran.c
adding x server license terms for polygon methods
[wxWidgets.git] / src / png / pngwtran.c
CommitLineData
0272a10d
VZ
1
2/* pngwtran.c - transforms the data in a row for PNG writers
3 *
9c0d9ce3
DS
4 * Last changed in libpng 1.5.6 [November 3, 2011]
5 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
0272a10d
VZ
6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
b61cc19c
PC
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
0272a10d
VZ
12 */
13
b61cc19c 14#include "pngpriv.h"
0272a10d 15
9c0d9ce3
DS
16#ifdef PNG_WRITE_SUPPORTED
17
18#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
0272a10d
VZ
19/* Transform the data according to the user's wishes. The order of
20 * transformations is significant.
21 */
22void /* PRIVATE */
9c0d9ce3 23png_do_write_transformations(png_structp png_ptr, png_row_infop row_info)
0272a10d 24{
970f6abe 25 png_debug(1, "in png_do_write_transformations");
0272a10d
VZ
26
27 if (png_ptr == NULL)
28 return;
29
b61cc19c 30#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
0272a10d 31 if (png_ptr->transformations & PNG_USER_TRANSFORM)
970f6abe 32 if (png_ptr->write_user_transform_fn != NULL)
9c0d9ce3 33 (*(png_ptr->write_user_transform_fn)) /* User write transform
b61cc19c 34 function */
9c0d9ce3
DS
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 */
0272a10d 44#endif
9c0d9ce3 45
b61cc19c 46#ifdef PNG_WRITE_FILLER_SUPPORTED
0272a10d 47 if (png_ptr->transformations & PNG_FILLER)
9c0d9ce3
DS
48 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
49 !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
0272a10d 50#endif
9c0d9ce3 51
b61cc19c 52#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
0272a10d 53 if (png_ptr->transformations & PNG_PACKSWAP)
9c0d9ce3 54 png_do_packswap(row_info, png_ptr->row_buf + 1);
0272a10d 55#endif
9c0d9ce3 56
b61cc19c 57#ifdef PNG_WRITE_PACK_SUPPORTED
0272a10d 58 if (png_ptr->transformations & PNG_PACK)
9c0d9ce3
DS
59 png_do_pack(row_info, png_ptr->row_buf + 1,
60 (png_uint_32)png_ptr->bit_depth);
0272a10d 61#endif
9c0d9ce3 62
b61cc19c 63#ifdef PNG_WRITE_SWAP_SUPPORTED
0272a10d 64 if (png_ptr->transformations & PNG_SWAP_BYTES)
9c0d9ce3 65 png_do_swap(row_info, png_ptr->row_buf + 1);
0272a10d 66#endif
9c0d9ce3 67
b61cc19c 68#ifdef PNG_WRITE_SHIFT_SUPPORTED
0272a10d 69 if (png_ptr->transformations & PNG_SHIFT)
9c0d9ce3
DS
70 png_do_shift(row_info, png_ptr->row_buf + 1,
71 &(png_ptr->shift));
0272a10d 72#endif
9c0d9ce3 73
b61cc19c 74#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
0272a10d 75 if (png_ptr->transformations & PNG_SWAP_ALPHA)
9c0d9ce3 76 png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
0272a10d 77#endif
9c0d9ce3 78
b61cc19c 79#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
0272a10d 80 if (png_ptr->transformations & PNG_INVERT_ALPHA)
9c0d9ce3 81 png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
0272a10d 82#endif
9c0d9ce3 83
b61cc19c 84#ifdef PNG_WRITE_BGR_SUPPORTED
0272a10d 85 if (png_ptr->transformations & PNG_BGR)
9c0d9ce3 86 png_do_bgr(row_info, png_ptr->row_buf + 1);
0272a10d 87#endif
9c0d9ce3 88
b61cc19c 89#ifdef PNG_WRITE_INVERT_SUPPORTED
0272a10d 90 if (png_ptr->transformations & PNG_INVERT_MONO)
9c0d9ce3 91 png_do_invert(row_info, png_ptr->row_buf + 1);
0272a10d
VZ
92#endif
93}
94
b61cc19c 95#ifdef PNG_WRITE_PACK_SUPPORTED
0272a10d
VZ
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 */
100void /* PRIVATE */
101png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
102{
970f6abe 103 png_debug(1, "in png_do_pack");
b61cc19c 104
0272a10d 105 if (row_info->bit_depth == 8 &&
0272a10d
VZ
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;
9c0d9ce3 126
0272a10d 127 sp++;
9c0d9ce3 128
0272a10d
VZ
129 if (mask > 1)
130 mask >>= 1;
9c0d9ce3 131
0272a10d
VZ
132 else
133 {
134 mask = 0x80;
135 *dp = (png_byte)v;
136 dp++;
137 v = 0;
138 }
139 }
9c0d9ce3 140
0272a10d
VZ
141 if (mask != 0x80)
142 *dp = (png_byte)v;
9c0d9ce3 143
0272a10d
VZ
144 break;
145 }
9c0d9ce3 146
0272a10d
VZ
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;
9c0d9ce3 158
0272a10d
VZ
159 for (i = 0; i < row_width; i++)
160 {
161 png_byte value;
162
163 value = (png_byte)(*sp & 0x03);
164 v |= (value << shift);
9c0d9ce3 165
0272a10d
VZ
166 if (shift == 0)
167 {
168 shift = 6;
169 *dp = (png_byte)v;
170 dp++;
171 v = 0;
172 }
9c0d9ce3 173
0272a10d
VZ
174 else
175 shift -= 2;
9c0d9ce3 176
0272a10d
VZ
177 sp++;
178 }
9c0d9ce3 179
0272a10d
VZ
180 if (shift != 6)
181 *dp = (png_byte)v;
9c0d9ce3 182
0272a10d
VZ
183 break;
184 }
9c0d9ce3 185
0272a10d
VZ
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;
9c0d9ce3 197
0272a10d
VZ
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 }
9c0d9ce3 212
0272a10d
VZ
213 else
214 shift -= 4;
215
216 sp++;
217 }
9c0d9ce3 218
0272a10d
VZ
219 if (shift != 4)
220 *dp = (png_byte)v;
9c0d9ce3 221
0272a10d
VZ
222 break;
223 }
9c0d9ce3
DS
224
225 default:
226 break;
0272a10d 227 }
9c0d9ce3 228
0272a10d
VZ
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,
9c0d9ce3 232 row_info->width);
0272a10d
VZ
233 }
234}
235#endif
236
b61cc19c 237#ifdef PNG_WRITE_SHIFT_SUPPORTED
0272a10d
VZ
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 */
245void /* PRIVATE */
9c0d9ce3
DS
246png_do_shift(png_row_infop row_info, png_bytep row,
247 png_const_color_8p bit_depth)
0272a10d 248{
970f6abe 249 png_debug(1, "in png_do_shift");
b61cc19c 250
9c0d9ce3 251 if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
0272a10d
VZ
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++;
9c0d9ce3 261
0272a10d
VZ
262 shift_start[channels] = row_info->bit_depth - bit_depth->green;
263 shift_dec[channels] = bit_depth->green;
264 channels++;
9c0d9ce3 265
0272a10d
VZ
266 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
267 shift_dec[channels] = bit_depth->blue;
268 channels++;
269 }
9c0d9ce3 270
0272a10d
VZ
271 else
272 {
273 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
274 shift_dec[channels] = bit_depth->gray;
275 channels++;
276 }
9c0d9ce3 277
0272a10d
VZ
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
b61cc19c 285 /* With low row depths, could only be grayscale, so one channel */
0272a10d
VZ
286 if (row_info->bit_depth < 8)
287 {
288 png_bytep bp = row;
9c0d9ce3 289 png_size_t i;
0272a10d 290 png_byte mask;
9c0d9ce3 291 png_size_t row_bytes = row_info->rowbytes;
0272a10d
VZ
292
293 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
294 mask = 0x55;
9c0d9ce3 295
0272a10d
VZ
296 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
297 mask = 0x11;
9c0d9ce3 298
0272a10d
VZ
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;
9c0d9ce3 309
0272a10d
VZ
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);
9c0d9ce3 314
0272a10d
VZ
315 else
316 *bp |= (png_byte)((v >> (-j)) & mask);
317 }
318 }
319 }
9c0d9ce3 320
0272a10d
VZ
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;
9c0d9ce3 336
0272a10d
VZ
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);
9c0d9ce3 341
0272a10d
VZ
342 else
343 *bp |= (png_byte)((v >> (-j)) & 0xff);
344 }
345 }
346 }
9c0d9ce3 347
0272a10d
VZ
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;
9c0d9ce3 362
0272a10d
VZ
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);
9c0d9ce3 367
0272a10d
VZ
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
b61cc19c 379#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
0272a10d
VZ
380void /* PRIVATE */
381png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
382{
970f6abe 383 png_debug(1, "in png_do_write_swap_alpha");
b61cc19c 384
0272a10d
VZ
385 {
386 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
387 {
0272a10d
VZ
388 if (row_info->bit_depth == 8)
389 {
9c0d9ce3 390 /* This converts from ARGB to RGBA */
0272a10d
VZ
391 png_bytep sp, dp;
392 png_uint_32 i;
393 png_uint_32 row_width = row_info->width;
9c0d9ce3 394
0272a10d
VZ
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 }
9c0d9ce3
DS
404
405#ifdef PNG_WRITE_16BIT_SUPPORTED
0272a10d
VZ
406 else
407 {
9c0d9ce3 408 /* This converts from AARRGGBB to RRGGBBAA */
0272a10d
VZ
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 }
9c0d9ce3 428#endif /* PNG_WRITE_16BIT_SUPPORTED */
0272a10d 429 }
9c0d9ce3 430
0272a10d
VZ
431 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
432 {
0272a10d
VZ
433 if (row_info->bit_depth == 8)
434 {
9c0d9ce3 435 /* This converts from AG to GA */
0272a10d
VZ
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 }
9c0d9ce3
DS
447
448#ifdef PNG_WRITE_16BIT_SUPPORTED
0272a10d
VZ
449 else
450 {
9c0d9ce3 451 /* This converts from AAGG to GGAA */
0272a10d
VZ
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 }
9c0d9ce3 467#endif /* PNG_WRITE_16BIT_SUPPORTED */
0272a10d
VZ
468 }
469 }
470}
471#endif
472
b61cc19c 473#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
0272a10d
VZ
474void /* PRIVATE */
475png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
476{
970f6abe 477 png_debug(1, "in png_do_write_invert_alpha");
b61cc19c 478
0272a10d
VZ
479 {
480 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
481 {
0272a10d
VZ
482 if (row_info->bit_depth == 8)
483 {
9c0d9ce3 484 /* This inverts the alpha channel in RGBA */
0272a10d
VZ
485 png_bytep sp, dp;
486 png_uint_32 i;
487 png_uint_32 row_width = row_info->width;
9c0d9ce3 488
0272a10d
VZ
489 for (i = 0, sp = dp = row; i < row_width; i++)
490 {
b61cc19c 491 /* Does nothing
0272a10d
VZ
492 *(dp++) = *(sp++);
493 *(dp++) = *(sp++);
494 *(dp++) = *(sp++);
495 */
496 sp+=3; dp = sp;
497 *(dp++) = (png_byte)(255 - *(sp++));
498 }
499 }
9c0d9ce3
DS
500
501#ifdef PNG_WRITE_16BIT_SUPPORTED
0272a10d
VZ
502 else
503 {
9c0d9ce3 504 /* This inverts the alpha channel in RRGGBBAA */
0272a10d
VZ
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 {
b61cc19c 511 /* Does nothing
0272a10d
VZ
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 }
9c0d9ce3 524#endif /* PNG_WRITE_16BIT_SUPPORTED */
0272a10d 525 }
9c0d9ce3 526
0272a10d
VZ
527 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
528 {
0272a10d
VZ
529 if (row_info->bit_depth == 8)
530 {
9c0d9ce3 531 /* This inverts the alpha channel in GA */
0272a10d
VZ
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 }
9c0d9ce3
DS
542
543#ifdef PNG_WRITE_16BIT_SUPPORTED
0272a10d
VZ
544 else
545 {
9c0d9ce3 546 /* This inverts the alpha channel in GGAA */
0272a10d
VZ
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 {
b61cc19c 553 /* Does nothing
0272a10d
VZ
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 }
9c0d9ce3 562#endif /* PNG_WRITE_16BIT_SUPPORTED */
0272a10d
VZ
563 }
564 }
565}
566#endif
9c0d9ce3 567#endif /* PNG_WRITE_TRANSFORMS_SUPPORTED */
0272a10d 568
b61cc19c
PC
569#ifdef PNG_MNG_FEATURES_SUPPORTED
570/* Undoes intrapixel differencing */
0272a10d
VZ
571void /* PRIVATE */
572png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
573{
970f6abe 574 png_debug(1, "in png_do_write_intrapixel");
b61cc19c 575
9c0d9ce3 576 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
0272a10d
VZ
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;
9c0d9ce3 587
0272a10d
VZ
588 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
589 bytes_per_pixel = 4;
9c0d9ce3 590
0272a10d
VZ
591 else
592 return;
593
594 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
595 {
9c0d9ce3
DS
596 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
597 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
0272a10d
VZ
598 }
599 }
9c0d9ce3
DS
600
601#ifdef PNG_WRITE_16BIT_SUPPORTED
0272a10d
VZ
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;
9c0d9ce3 609
0272a10d
VZ
610 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
611 bytes_per_pixel = 8;
9c0d9ce3 612
0272a10d
VZ
613 else
614 return;
615
616 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
617 {
9c0d9ce3
DS
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);
970f6abe
VZ
621 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
622 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
9c0d9ce3
DS
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);
0272a10d
VZ
627 }
628 }
9c0d9ce3 629#endif /* PNG_WRITE_16BIT_SUPPORTED */
0272a10d
VZ
630 }
631}
632#endif /* PNG_MNG_FEATURES_SUPPORTED */
633#endif /* PNG_WRITE_SUPPORTED */