pngwtran.c
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1 
2 /* pngwtran.c - transforms the data in a row for PNG writers
3  *
4  * Last changed in libpng 1.2.9 April 14, 2006
5  * For conditions of distribution and use, see copyright notice in png.h
6  * Copyright (c) 1998-2006 Glenn Randers-Pehrson
7  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
8  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
9  */
10 
11 #define PNG_INTERNAL
12 #include "png.h"
13 #ifdef PNG_WRITE_SUPPORTED
14 
15 /* Transform the data according to the user's wishes. The order of
16  * transformations is significant.
17  */
18 void /* PRIVATE */
20 {
21  png_debug(1, "in png_do_write_transformations\n");
22 
23  if (png_ptr == NULL)
24  return;
25 
26 #if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
27  if (png_ptr->transformations & PNG_USER_TRANSFORM)
28  if (png_ptr->write_user_transform_fn != NULL)
29  (*(png_ptr->write_user_transform_fn)) /* user write transform function */
30  (png_ptr, /* png_ptr */
31  &(png_ptr->row_info), /* row_info: */
32  /* png_uint_32 width; width of row */
33  /* png_uint_32 rowbytes; number of bytes in row */
34  /* png_byte color_type; color type of pixels */
35  /* png_byte bit_depth; bit depth of samples */
36  /* png_byte channels; number of channels (1-4) */
37  /* png_byte pixel_depth; bits per pixel (depth*channels) */
38  png_ptr->row_buf + 1); /* start of pixel data for row */
39 #endif
40 #if defined(PNG_WRITE_FILLER_SUPPORTED)
41  if (png_ptr->transformations & PNG_FILLER)
42  png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
43  png_ptr->flags);
44 #endif
45 #if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
46  if (png_ptr->transformations & PNG_PACKSWAP)
47  png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
48 #endif
49 #if defined(PNG_WRITE_PACK_SUPPORTED)
50  if (png_ptr->transformations & PNG_PACK)
51  png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
52  (png_uint_32)png_ptr->bit_depth);
53 #endif
54 #if defined(PNG_WRITE_SWAP_SUPPORTED)
55  if (png_ptr->transformations & PNG_SWAP_BYTES)
56  png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
57 #endif
58 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
59  if (png_ptr->transformations & PNG_SHIFT)
60  png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
61  &(png_ptr->shift));
62 #endif
63 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
64  if (png_ptr->transformations & PNG_SWAP_ALPHA)
65  png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
66 #endif
67 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
68  if (png_ptr->transformations & PNG_INVERT_ALPHA)
69  png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
70 #endif
71 #if defined(PNG_WRITE_BGR_SUPPORTED)
72  if (png_ptr->transformations & PNG_BGR)
73  png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
74 #endif
75 #if defined(PNG_WRITE_INVERT_SUPPORTED)
76  if (png_ptr->transformations & PNG_INVERT_MONO)
77  png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
78 #endif
79 }
80 
81 #if defined(PNG_WRITE_PACK_SUPPORTED)
82 /* Pack pixels into bytes. Pass the true bit depth in bit_depth. The
83  * row_info bit depth should be 8 (one pixel per byte). The channels
84  * should be 1 (this only happens on grayscale and paletted images).
85  */
86 void /* PRIVATE */
88 {
89  png_debug(1, "in png_do_pack\n");
90  if (row_info->bit_depth == 8 &&
91 #if defined(PNG_USELESS_TESTS_SUPPORTED)
92  row != NULL && row_info != NULL &&
93 #endif
94  row_info->channels == 1)
95  {
96  switch ((int)bit_depth)
97  {
98  case 1:
99  {
100  png_bytep sp, dp;
101  int mask, v;
102  png_uint_32 i;
103  png_uint_32 row_width = row_info->width;
104 
105  sp = row;
106  dp = row;
107  mask = 0x80;
108  v = 0;
109 
110  for (i = 0; i < row_width; i++)
111  {
112  if (*sp != 0)
113  v |= mask;
114  sp++;
115  if (mask > 1)
116  mask >>= 1;
117  else
118  {
119  mask = 0x80;
120  *dp = (png_byte)v;
121  dp++;
122  v = 0;
123  }
124  }
125  if (mask != 0x80)
126  *dp = (png_byte)v;
127  break;
128  }
129  case 2:
130  {
131  png_bytep sp, dp;
132  int shift, v;
133  png_uint_32 i;
134  png_uint_32 row_width = row_info->width;
135 
136  sp = row;
137  dp = row;
138  shift = 6;
139  v = 0;
140  for (i = 0; i < row_width; i++)
141  {
142  png_byte value;
143 
144  value = (png_byte)(*sp & 0x03);
145  v |= (value << shift);
146  if (shift == 0)
147  {
148  shift = 6;
149  *dp = (png_byte)v;
150  dp++;
151  v = 0;
152  }
153  else
154  shift -= 2;
155  sp++;
156  }
157  if (shift != 6)
158  *dp = (png_byte)v;
159  break;
160  }
161  case 4:
162  {
163  png_bytep sp, dp;
164  int shift, v;
165  png_uint_32 i;
166  png_uint_32 row_width = row_info->width;
167 
168  sp = row;
169  dp = row;
170  shift = 4;
171  v = 0;
172  for (i = 0; i < row_width; i++)
173  {
174  png_byte value;
175 
176  value = (png_byte)(*sp & 0x0f);
177  v |= (value << shift);
178 
179  if (shift == 0)
180  {
181  shift = 4;
182  *dp = (png_byte)v;
183  dp++;
184  v = 0;
185  }
186  else
187  shift -= 4;
188 
189  sp++;
190  }
191  if (shift != 4)
192  *dp = (png_byte)v;
193  break;
194  }
195  }
196  row_info->bit_depth = (png_byte)bit_depth;
197  row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
198  row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
199  row_info->width);
200  }
201 }
202 #endif
203 
204 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
205 /* Shift pixel values to take advantage of whole range. Pass the
206  * true number of bits in bit_depth. The row should be packed
207  * according to row_info->bit_depth. Thus, if you had a row of
208  * bit depth 4, but the pixels only had values from 0 to 7, you
209  * would pass 3 as bit_depth, and this routine would translate the
210  * data to 0 to 15.
211  */
212 void /* PRIVATE */
214 {
215  png_debug(1, "in png_do_shift\n");
216 #if defined(PNG_USELESS_TESTS_SUPPORTED)
217  if (row != NULL && row_info != NULL &&
218 #else
219  if (
220 #endif
221  row_info->color_type != PNG_COLOR_TYPE_PALETTE)
222  {
223  int shift_start[4], shift_dec[4];
224  int channels = 0;
225 
226  if (row_info->color_type & PNG_COLOR_MASK_COLOR)
227  {
228  shift_start[channels] = row_info->bit_depth - bit_depth->red;
229  shift_dec[channels] = bit_depth->red;
230  channels++;
231  shift_start[channels] = row_info->bit_depth - bit_depth->green;
232  shift_dec[channels] = bit_depth->green;
233  channels++;
234  shift_start[channels] = row_info->bit_depth - bit_depth->blue;
235  shift_dec[channels] = bit_depth->blue;
236  channels++;
237  }
238  else
239  {
240  shift_start[channels] = row_info->bit_depth - bit_depth->gray;
241  shift_dec[channels] = bit_depth->gray;
242  channels++;
243  }
244  if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
245  {
246  shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
247  shift_dec[channels] = bit_depth->alpha;
248  channels++;
249  }
250 
251  /* with low row depths, could only be grayscale, so one channel */
252  if (row_info->bit_depth < 8)
253  {
254  png_bytep bp = row;
255  png_uint_32 i;
256  png_byte mask;
257  png_uint_32 row_bytes = row_info->rowbytes;
258 
259  if (bit_depth->gray == 1 && row_info->bit_depth == 2)
260  mask = 0x55;
261  else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
262  mask = 0x11;
263  else
264  mask = 0xff;
265 
266  for (i = 0; i < row_bytes; i++, bp++)
267  {
268  png_uint_16 v;
269  int j;
270 
271  v = *bp;
272  *bp = 0;
273  for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
274  {
275  if (j > 0)
276  *bp |= (png_byte)((v << j) & 0xff);
277  else
278  *bp |= (png_byte)((v >> (-j)) & mask);
279  }
280  }
281  }
282  else if (row_info->bit_depth == 8)
283  {
284  png_bytep bp = row;
285  png_uint_32 i;
286  png_uint_32 istop = channels * row_info->width;
287 
288  for (i = 0; i < istop; i++, bp++)
289  {
290 
291  png_uint_16 v;
292  int j;
293  int c = (int)(i%channels);
294 
295  v = *bp;
296  *bp = 0;
297  for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
298  {
299  if (j > 0)
300  *bp |= (png_byte)((v << j) & 0xff);
301  else
302  *bp |= (png_byte)((v >> (-j)) & 0xff);
303  }
304  }
305  }
306  else
307  {
308  png_bytep bp;
309  png_uint_32 i;
310  png_uint_32 istop = channels * row_info->width;
311 
312  for (bp = row, i = 0; i < istop; i++)
313  {
314  int c = (int)(i%channels);
315  png_uint_16 value, v;
316  int j;
317 
318  v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
319  value = 0;
320  for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
321  {
322  if (j > 0)
323  value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
324  else
325  value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
326  }
327  *bp++ = (png_byte)(value >> 8);
328  *bp++ = (png_byte)(value & 0xff);
329  }
330  }
331  }
332 }
333 #endif
334 
335 #if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
336 void /* PRIVATE */
338 {
339  png_debug(1, "in png_do_write_swap_alpha\n");
340 #if defined(PNG_USELESS_TESTS_SUPPORTED)
341  if (row != NULL && row_info != NULL)
342 #endif
343  {
344  if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
345  {
346  /* This converts from ARGB to RGBA */
347  if (row_info->bit_depth == 8)
348  {
349  png_bytep sp, dp;
350  png_uint_32 i;
351  png_uint_32 row_width = row_info->width;
352  for (i = 0, sp = dp = row; i < row_width; i++)
353  {
354  png_byte save = *(sp++);
355  *(dp++) = *(sp++);
356  *(dp++) = *(sp++);
357  *(dp++) = *(sp++);
358  *(dp++) = save;
359  }
360  }
361  /* This converts from AARRGGBB to RRGGBBAA */
362  else
363  {
364  png_bytep sp, dp;
365  png_uint_32 i;
366  png_uint_32 row_width = row_info->width;
367 
368  for (i = 0, sp = dp = row; i < row_width; i++)
369  {
370  png_byte save[2];
371  save[0] = *(sp++);
372  save[1] = *(sp++);
373  *(dp++) = *(sp++);
374  *(dp++) = *(sp++);
375  *(dp++) = *(sp++);
376  *(dp++) = *(sp++);
377  *(dp++) = *(sp++);
378  *(dp++) = *(sp++);
379  *(dp++) = save[0];
380  *(dp++) = save[1];
381  }
382  }
383  }
384  else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
385  {
386  /* This converts from AG to GA */
387  if (row_info->bit_depth == 8)
388  {
389  png_bytep sp, dp;
390  png_uint_32 i;
391  png_uint_32 row_width = row_info->width;
392 
393  for (i = 0, sp = dp = row; i < row_width; i++)
394  {
395  png_byte save = *(sp++);
396  *(dp++) = *(sp++);
397  *(dp++) = save;
398  }
399  }
400  /* This converts from AAGG to GGAA */
401  else
402  {
403  png_bytep sp, dp;
404  png_uint_32 i;
405  png_uint_32 row_width = row_info->width;
406 
407  for (i = 0, sp = dp = row; i < row_width; i++)
408  {
409  png_byte save[2];
410  save[0] = *(sp++);
411  save[1] = *(sp++);
412  *(dp++) = *(sp++);
413  *(dp++) = *(sp++);
414  *(dp++) = save[0];
415  *(dp++) = save[1];
416  }
417  }
418  }
419  }
420 }
421 #endif
422 
423 #if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
424 void /* PRIVATE */
426 {
427  png_debug(1, "in png_do_write_invert_alpha\n");
428 #if defined(PNG_USELESS_TESTS_SUPPORTED)
429  if (row != NULL && row_info != NULL)
430 #endif
431  {
432  if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
433  {
434  /* This inverts the alpha channel in RGBA */
435  if (row_info->bit_depth == 8)
436  {
437  png_bytep sp, dp;
438  png_uint_32 i;
439  png_uint_32 row_width = row_info->width;
440  for (i = 0, sp = dp = row; i < row_width; i++)
441  {
442  /* does nothing
443  *(dp++) = *(sp++);
444  *(dp++) = *(sp++);
445  *(dp++) = *(sp++);
446  */
447  sp+=3; dp = sp;
448  *(dp++) = (png_byte)(255 - *(sp++));
449  }
450  }
451  /* This inverts the alpha channel in RRGGBBAA */
452  else
453  {
454  png_bytep sp, dp;
455  png_uint_32 i;
456  png_uint_32 row_width = row_info->width;
457 
458  for (i = 0, sp = dp = row; i < row_width; i++)
459  {
460  /* does nothing
461  *(dp++) = *(sp++);
462  *(dp++) = *(sp++);
463  *(dp++) = *(sp++);
464  *(dp++) = *(sp++);
465  *(dp++) = *(sp++);
466  *(dp++) = *(sp++);
467  */
468  sp+=6; dp = sp;
469  *(dp++) = (png_byte)(255 - *(sp++));
470  *(dp++) = (png_byte)(255 - *(sp++));
471  }
472  }
473  }
474  else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
475  {
476  /* This inverts the alpha channel in GA */
477  if (row_info->bit_depth == 8)
478  {
479  png_bytep sp, dp;
480  png_uint_32 i;
481  png_uint_32 row_width = row_info->width;
482 
483  for (i = 0, sp = dp = row; i < row_width; i++)
484  {
485  *(dp++) = *(sp++);
486  *(dp++) = (png_byte)(255 - *(sp++));
487  }
488  }
489  /* This inverts the alpha channel in GGAA */
490  else
491  {
492  png_bytep sp, dp;
493  png_uint_32 i;
494  png_uint_32 row_width = row_info->width;
495 
496  for (i = 0, sp = dp = row; i < row_width; i++)
497  {
498  /* does nothing
499  *(dp++) = *(sp++);
500  *(dp++) = *(sp++);
501  */
502  sp+=2; dp = sp;
503  *(dp++) = (png_byte)(255 - *(sp++));
504  *(dp++) = (png_byte)(255 - *(sp++));
505  }
506  }
507  }
508  }
509 }
510 #endif
511 
512 #if defined(PNG_MNG_FEATURES_SUPPORTED)
513 /* undoes intrapixel differencing */
514 void /* PRIVATE */
516 {
517  png_debug(1, "in png_do_write_intrapixel\n");
518  if (
519 #if defined(PNG_USELESS_TESTS_SUPPORTED)
520  row != NULL && row_info != NULL &&
521 #endif
522  (row_info->color_type & PNG_COLOR_MASK_COLOR))
523  {
524  int bytes_per_pixel;
525  png_uint_32 row_width = row_info->width;
526  if (row_info->bit_depth == 8)
527  {
528  png_bytep rp;
529  png_uint_32 i;
530 
531  if (row_info->color_type == PNG_COLOR_TYPE_RGB)
532  bytes_per_pixel = 3;
533  else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
534  bytes_per_pixel = 4;
535  else
536  return;
537 
538  for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
539  {
540  *(rp) = (png_byte)((*rp - *(rp+1))&0xff);
541  *(rp+2) = (png_byte)((*(rp+2) - *(rp+1))&0xff);
542  }
543  }
544  else if (row_info->bit_depth == 16)
545  {
546  png_bytep rp;
547  png_uint_32 i;
548 
549  if (row_info->color_type == PNG_COLOR_TYPE_RGB)
550  bytes_per_pixel = 6;
551  else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
552  bytes_per_pixel = 8;
553  else
554  return;
555 
556  for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
557  {
558  png_uint_32 s0 = (*(rp ) << 8) | *(rp+1);
559  png_uint_32 s1 = (*(rp+2) << 8) | *(rp+3);
560  png_uint_32 s2 = (*(rp+4) << 8) | *(rp+5);
561  png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
562  png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
563  *(rp ) = (png_byte)((red >> 8) & 0xff);
564  *(rp+1) = (png_byte)(red & 0xff);
565  *(rp+4) = (png_byte)((blue >> 8) & 0xff);
566  *(rp+5) = (png_byte)(blue & 0xff);
567  }
568  }
569  }
570 }
571 #endif /* PNG_MNG_FEATURES_SUPPORTED */
572 #endif /* PNG_WRITE_SUPPORTED */
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openhrp3
Author(s): AIST, General Robotix Inc., Nakamura Lab of Dept. of Mechano Informatics at University of Tokyo
autogenerated on Wed Sep 7 2022 02:51:04