1
2/* pngwtran.c - transforms the data in a row for PNG writers
3 *
4 * Last changed in libpng 1.6.18 [July 23, 2015]
5 * Copyright (c) 1998-2002,2004,2006-2015 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#ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
18
19#ifdef PNG_WRITE_PACK_SUPPORTED
20/* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
21 * row_info bit depth should be 8 (one pixel per byte). The channels
22 * should be 1 (this only happens on grayscale and paletted images).
23 */
24static void
25png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
26{
27 png_debug(1, "in png_do_pack");
28
29 if (row_info->bit_depth == 8 &&
30 row_info->channels == 1)
31 {
32 switch ((int)bit_depth)
33 {
34 case 1:
35 {
36 png_bytep sp, dp;
37 int mask, v;
38 png_uint_32 i;
39 png_uint_32 row_width = row_info->width;
40
41 sp = row;
42 dp = row;
43 mask = 0x80;
44 v = 0;
45
46 for (i = 0; i < row_width; i++)
47 {
48 if (*sp != 0)
49 v |= mask;
50
51 sp++;
52
53 if (mask > 1)
54 mask >>= 1;
55
56 else
57 {
58 mask = 0x80;
59 *dp = (png_byte)v;
60 dp++;
61 v = 0;
62 }
63 }
64
65 if (mask != 0x80)
66 *dp = (png_byte)v;
67
68 break;
69 }
70
71 case 2:
72 {
73 png_bytep sp, dp;
74 unsigned int shift;
75 int v;
76 png_uint_32 i;
77 png_uint_32 row_width = row_info->width;
78
79 sp = row;
80 dp = row;
81 shift = 6;
82 v = 0;
83
84 for (i = 0; i < row_width; i++)
85 {
86 png_byte value;
87
88 value = (png_byte)(*sp & 0x03);
89 v |= (value << shift);
90
91 if (shift == 0)
92 {
93 shift = 6;
94 *dp = (png_byte)v;
95 dp++;
96 v = 0;
97 }
98
99 else
100 shift -= 2;
101
102 sp++;
103 }
104
105 if (shift != 6)
106 *dp = (png_byte)v;
107
108 break;
109 }
110
111 case 4:
112 {
113 png_bytep sp, dp;
114 unsigned int shift;
115 int v;
116 png_uint_32 i;
117 png_uint_32 row_width = row_info->width;
118
119 sp = row;
120 dp = row;
121 shift = 4;
122 v = 0;
123
124 for (i = 0; i < row_width; i++)
125 {
126 png_byte value;
127
128 value = (png_byte)(*sp & 0x0f);
129 v |= (value << shift);
130
131 if (shift == 0)
132 {
133 shift = 4;
134 *dp = (png_byte)v;
135 dp++;
136 v = 0;
137 }
138
139 else
140 shift -= 4;
141
142 sp++;
143 }
144
145 if (shift != 4)
146 *dp = (png_byte)v;
147
148 break;
149 }
150
151 default:
152 break;
153 }
154
155 row_info->bit_depth = (png_byte)bit_depth;
156 row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
157 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
158 row_info->width);
159 }
160}
161#endif
162
163#ifdef PNG_WRITE_SHIFT_SUPPORTED
164/* Shift pixel values to take advantage of whole range. Pass the
165 * true number of bits in bit_depth. The row should be packed
166 * according to row_info->bit_depth. Thus, if you had a row of
167 * bit depth 4, but the pixels only had values from 0 to 7, you
168 * would pass 3 as bit_depth, and this routine would translate the
169 * data to 0 to 15.
170 */
171static void
172png_do_shift(png_row_infop row_info, png_bytep row,
173 png_const_color_8p bit_depth)
174{
175 png_debug(1, "in png_do_shift");
176
177 if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
178 {
179 int shift_start[4], shift_dec[4];
180 int channels = 0;
181
182 if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
183 {
184 shift_start[channels] = row_info->bit_depth - bit_depth->red;
185 shift_dec[channels] = bit_depth->red;
186 channels++;
187
188 shift_start[channels] = row_info->bit_depth - bit_depth->green;
189 shift_dec[channels] = bit_depth->green;
190 channels++;
191
192 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
193 shift_dec[channels] = bit_depth->blue;
194 channels++;
195 }
196
197 else
198 {
199 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
200 shift_dec[channels] = bit_depth->gray;
201 channels++;
202 }
203
204 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
205 {
206 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
207 shift_dec[channels] = bit_depth->alpha;
208 channels++;
209 }
210
211 /* With low row depths, could only be grayscale, so one channel */
212 if (row_info->bit_depth < 8)
213 {
214 png_bytep bp = row;
215 png_size_t i;
216 unsigned int mask;
217 png_size_t row_bytes = row_info->rowbytes;
218
219 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
220 mask = 0x55;
221
222 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
223 mask = 0x11;
224
225 else
226 mask = 0xff;
227
228 for (i = 0; i < row_bytes; i++, bp++)
229 {
230 int j;
231 unsigned int v, out;
232
233 v = *bp;
234 out = 0;
235
236 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
237 {
238 if (j > 0)
239 out |= v << j;
240
241 else
242 out |= (v >> (-j)) & mask;
243 }
244
245 *bp = (png_byte)(out & 0xff);
246 }
247 }
248
249 else if (row_info->bit_depth == 8)
250 {
251 png_bytep bp = row;
252 png_uint_32 i;
253 png_uint_32 istop = channels * row_info->width;
254
255 for (i = 0; i < istop; i++, bp++)
256 {
257
258 const unsigned int c = i%channels;
259 int j;
260 unsigned int v, out;
261
262 v = *bp;
263 out = 0;
264
265 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
266 {
267 if (j > 0)
268 out |= v << j;
269
270 else
271 out |= v >> (-j);
272 }
273
274 *bp = (png_byte)(out & 0xff);
275 }
276 }
277
278 else
279 {
280 png_bytep bp;
281 png_uint_32 i;
282 png_uint_32 istop = channels * row_info->width;
283
284 for (bp = row, i = 0; i < istop; i++)
285 {
286 const unsigned int c = i%channels;
287 int j;
288 unsigned int value, v;
289
290 v = png_get_uint_16(bp);
291 value = 0;
292
293 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
294 {
295 if (j > 0)
296 value |= v << j;
297
298 else
299 value |= v >> (-j);
300 }
301 *bp++ = (png_byte)((value >> 8) & 0xff);
302 *bp++ = (png_byte)(value & 0xff);
303 }
304 }
305 }
306}
307#endif
308
309#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
310static void
311png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
312{
313 png_debug(1, "in png_do_write_swap_alpha");
314
315 {
316 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
317 {
318 if (row_info->bit_depth == 8)
319 {
320 /* This converts from ARGB to RGBA */
321 png_bytep sp, dp;
322 png_uint_32 i;
323 png_uint_32 row_width = row_info->width;
324
325 for (i = 0, sp = dp = row; i < row_width; i++)
326 {
327 png_byte save = *(sp++);
328 *(dp++) = *(sp++);
329 *(dp++) = *(sp++);
330 *(dp++) = *(sp++);
331 *(dp++) = save;
332 }
333 }
334
335#ifdef PNG_WRITE_16BIT_SUPPORTED
336 else
337 {
338 /* This converts from AARRGGBB to RRGGBBAA */
339 png_bytep sp, dp;
340 png_uint_32 i;
341 png_uint_32 row_width = row_info->width;
342
343 for (i = 0, sp = dp = row; i < row_width; i++)
344 {
345 png_byte save[2];
346 save[0] = *(sp++);
347 save[1] = *(sp++);
348 *(dp++) = *(sp++);
349 *(dp++) = *(sp++);
350 *(dp++) = *(sp++);
351 *(dp++) = *(sp++);
352 *(dp++) = *(sp++);
353 *(dp++) = *(sp++);
354 *(dp++) = save[0];
355 *(dp++) = save[1];
356 }
357 }
358#endif /* WRITE_16BIT */
359 }
360
361 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
362 {
363 if (row_info->bit_depth == 8)
364 {
365 /* This converts from AG to GA */
366 png_bytep sp, dp;
367 png_uint_32 i;
368 png_uint_32 row_width = row_info->width;
369
370 for (i = 0, sp = dp = row; i < row_width; i++)
371 {
372 png_byte save = *(sp++);
373 *(dp++) = *(sp++);
374 *(dp++) = save;
375 }
376 }
377
378#ifdef PNG_WRITE_16BIT_SUPPORTED
379 else
380 {
381 /* This converts from AAGG to GGAA */
382 png_bytep sp, dp;
383 png_uint_32 i;
384 png_uint_32 row_width = row_info->width;
385
386 for (i = 0, sp = dp = row; i < row_width; i++)
387 {
388 png_byte save[2];
389 save[0] = *(sp++);
390 save[1] = *(sp++);
391 *(dp++) = *(sp++);
392 *(dp++) = *(sp++);
393 *(dp++) = save[0];
394 *(dp++) = save[1];
395 }
396 }
397#endif /* WRITE_16BIT */
398 }
399 }
400}
401#endif
402
403#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
404static void
405png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
406{
407 png_debug(1, "in png_do_write_invert_alpha");
408
409 {
410 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
411 {
412 if (row_info->bit_depth == 8)
413 {
414 /* This inverts the alpha channel in RGBA */
415 png_bytep sp, dp;
416 png_uint_32 i;
417 png_uint_32 row_width = row_info->width;
418
419 for (i = 0, sp = dp = row; i < row_width; i++)
420 {
421 /* Does nothing
422 *(dp++) = *(sp++);
423 *(dp++) = *(sp++);
424 *(dp++) = *(sp++);
425 */
426 sp+=3; dp = sp;
427 *dp = (png_byte)(255 - *(sp++));
428 }
429 }
430
431#ifdef PNG_WRITE_16BIT_SUPPORTED
432 else
433 {
434 /* This inverts the alpha channel in RRGGBBAA */
435 png_bytep sp, dp;
436 png_uint_32 i;
437 png_uint_32 row_width = row_info->width;
438
439 for (i = 0, sp = dp = row; i < row_width; i++)
440 {
441 /* Does nothing
442 *(dp++) = *(sp++);
443 *(dp++) = *(sp++);
444 *(dp++) = *(sp++);
445 *(dp++) = *(sp++);
446 *(dp++) = *(sp++);
447 *(dp++) = *(sp++);
448 */
449 sp+=6; dp = sp;
450 *(dp++) = (png_byte)(255 - *(sp++));
451 *dp = (png_byte)(255 - *(sp++));
452 }
453 }
454#endif /* WRITE_16BIT */
455 }
456
457 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
458 {
459 if (row_info->bit_depth == 8)
460 {
461 /* This inverts the alpha channel in GA */
462 png_bytep sp, dp;
463 png_uint_32 i;
464 png_uint_32 row_width = row_info->width;
465
466 for (i = 0, sp = dp = row; i < row_width; i++)
467 {
468 *(dp++) = *(sp++);
469 *(dp++) = (png_byte)(255 - *(sp++));
470 }
471 }
472
473#ifdef PNG_WRITE_16BIT_SUPPORTED
474 else
475 {
476 /* This inverts the alpha channel in GGAA */
477 png_bytep sp, dp;
478 png_uint_32 i;
479 png_uint_32 row_width = row_info->width;
480
481 for (i = 0, sp = dp = row; i < row_width; i++)
482 {
483 /* Does nothing
484 *(dp++) = *(sp++);
485 *(dp++) = *(sp++);
486 */
487 sp+=2; dp = sp;
488 *(dp++) = (png_byte)(255 - *(sp++));
489 *dp = (png_byte)(255 - *(sp++));
490 }
491 }
492#endif /* WRITE_16BIT */
493 }
494 }
495}
496#endif
497
498/* Transform the data according to the user's wishes. The order of
499 * transformations is significant.
500 */
501void /* PRIVATE */
502png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
503{
504 png_debug(1, "in png_do_write_transformations");
505
506 if (png_ptr == NULL)
507 return;
508
509#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
510 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
511 if (png_ptr->write_user_transform_fn != NULL)
512 (*(png_ptr->write_user_transform_fn)) /* User write transform
513 function */
514 (png_ptr, /* png_ptr */
515 row_info, /* row_info: */
516 /* png_uint_32 width; width of row */
517 /* png_size_t rowbytes; number of bytes in row */
518 /* png_byte color_type; color type of pixels */
519 /* png_byte bit_depth; bit depth of samples */
520 /* png_byte channels; number of channels (1-4) */
521 /* png_byte pixel_depth; bits per pixel (depth*channels) */
522 png_ptr->row_buf + 1); /* start of pixel data for row */
523#endif
524
525#ifdef PNG_WRITE_FILLER_SUPPORTED
526 if ((png_ptr->transformations & PNG_FILLER) != 0)
527 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
528 !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
529#endif
530
531#ifdef PNG_WRITE_PACKSWAP_SUPPORTED
532 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
533 png_do_packswap(row_info, png_ptr->row_buf + 1);
534#endif
535
536#ifdef PNG_WRITE_PACK_SUPPORTED
537 if ((png_ptr->transformations & PNG_PACK) != 0)
538 png_do_pack(row_info, png_ptr->row_buf + 1,
539 (png_uint_32)png_ptr->bit_depth);
540#endif
541
542#ifdef PNG_WRITE_SWAP_SUPPORTED
543# ifdef PNG_16BIT_SUPPORTED
544 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
545 png_do_swap(row_info, png_ptr->row_buf + 1);
546# endif
547#endif
548
549#ifdef PNG_WRITE_SHIFT_SUPPORTED
550 if ((png_ptr->transformations & PNG_SHIFT) != 0)
551 png_do_shift(row_info, png_ptr->row_buf + 1,
552 &(png_ptr->shift));
553#endif
554
555#ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
556 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
557 png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
558#endif
559
560#ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
561 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
562 png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
563#endif
564
565#ifdef PNG_WRITE_BGR_SUPPORTED
566 if ((png_ptr->transformations & PNG_BGR) != 0)
567 png_do_bgr(row_info, png_ptr->row_buf + 1);
568#endif
569
570#ifdef PNG_WRITE_INVERT_SUPPORTED
571 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
572 png_do_invert(row_info, png_ptr->row_buf + 1);
573#endif
574}
575#endif /* WRITE_TRANSFORMS */
576#endif /* WRITE */
577