2 /* pngwtran.c - transforms the data in a row for PNG writers
4 * Last changed in libpng 1.5.2 [March 31, 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.)
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
16 #ifdef PNG_WRITE_SUPPORTED
18 /* Transform the data according to the user's wishes. The order of
19 * transformations is significant.
22 png_do_write_transformations(png_structp png_ptr)
24 png_debug(1, "in png_do_write_transformations");
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
34 (png_ptr, /* png_ptr */
35 &(png_ptr->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 */
45 #ifdef PNG_WRITE_FILLER_SUPPORTED
46 if (png_ptr->transformations & PNG_FILLER)
47 png_do_strip_channel(&(png_ptr->row_info), png_ptr->row_buf + 1,
48 !(png_ptr->flags & PNG_FILLER_AFTER));
51 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
52 if (png_ptr->transformations & PNG_PACKSWAP)
53 png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
56 #ifdef PNG_WRITE_PACK_SUPPORTED
57 if (png_ptr->transformations & PNG_PACK)
58 png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
59 (png_uint_32)png_ptr->bit_depth);
62 #ifdef PNG_WRITE_SWAP_SUPPORTED
63 if (png_ptr->transformations & PNG_SWAP_BYTES)
64 png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
67 #ifdef PNG_WRITE_SHIFT_SUPPORTED
68 if (png_ptr->transformations & PNG_SHIFT)
69 png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
73 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
74 if (png_ptr->transformations & PNG_SWAP_ALPHA)
75 png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
78 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
79 if (png_ptr->transformations & PNG_INVERT_ALPHA)
80 png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
83 #ifdef PNG_WRITE_BGR_SUPPORTED
84 if (png_ptr->transformations & PNG_BGR)
85 png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
88 #ifdef PNG_WRITE_INVERT_SUPPORTED
89 if (png_ptr->transformations & PNG_INVERT_MONO)
90 png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
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).
100 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
102 png_debug(1, "in png_do_pack");
104 if (row_info->bit_depth == 8 &&
105 row_info->channels == 1)
107 switch ((int)bit_depth)
114 png_uint_32 row_width = row_info->width;
121 for (i = 0; i < row_width; i++)
151 png_uint_32 row_width = row_info->width;
158 for (i = 0; i < row_width; i++)
162 value = (png_byte)(*sp & 0x03);
163 v |= (value << shift);
190 png_uint_32 row_width = row_info->width;
197 for (i = 0; i < row_width; i++)
201 value = (png_byte)(*sp & 0x0f);
202 v |= (value << shift);
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,
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
245 png_do_shift(png_row_infop row_info, png_bytep row,
246 png_const_color_8p bit_depth)
248 png_debug(1, "in png_do_shift");
250 if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
252 int shift_start[4], shift_dec[4];
255 if (row_info->color_type & PNG_COLOR_MASK_COLOR)
257 shift_start[channels] = row_info->bit_depth - bit_depth->red;
258 shift_dec[channels] = bit_depth->red;
261 shift_start[channels] = row_info->bit_depth - bit_depth->green;
262 shift_dec[channels] = bit_depth->green;
265 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
266 shift_dec[channels] = bit_depth->blue;
272 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
273 shift_dec[channels] = bit_depth->gray;
277 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
279 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
280 shift_dec[channels] = bit_depth->alpha;
284 /* With low row depths, could only be grayscale, so one channel */
285 if (row_info->bit_depth < 8)
290 png_size_t row_bytes = row_info->rowbytes;
292 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
295 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
301 for (i = 0; i < row_bytes; i++, bp++)
309 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
312 *bp |= (png_byte)((v << j) & 0xff);
315 *bp |= (png_byte)((v >> (-j)) & mask);
320 else if (row_info->bit_depth == 8)
324 png_uint_32 istop = channels * row_info->width;
326 for (i = 0; i < istop; i++, bp++)
331 int c = (int)(i%channels);
336 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
339 *bp |= (png_byte)((v << j) & 0xff);
342 *bp |= (png_byte)((v >> (-j)) & 0xff);
351 png_uint_32 istop = channels * row_info->width;
353 for (bp = row, i = 0; i < istop; i++)
355 int c = (int)(i%channels);
356 png_uint_16 value, v;
359 v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
362 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
365 value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
368 value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
370 *bp++ = (png_byte)(value >> 8);
371 *bp++ = (png_byte)(value & 0xff);
378 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
380 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
382 png_debug(1, "in png_do_write_swap_alpha");
385 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
387 if (row_info->bit_depth == 8)
389 /* This converts from ARGB to RGBA */
392 png_uint_32 row_width = row_info->width;
394 for (i = 0, sp = dp = row; i < row_width; i++)
396 png_byte save = *(sp++);
404 #ifdef PNG_WRITE_16BIT_SUPPORTED
407 /* This converts from AARRGGBB to RRGGBBAA */
410 png_uint_32 row_width = row_info->width;
412 for (i = 0, sp = dp = row; i < row_width; i++)
427 #endif /* PNG_WRITE_16BIT_SUPPORTED */
430 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
432 if (row_info->bit_depth == 8)
434 /* This converts from AG to GA */
437 png_uint_32 row_width = row_info->width;
439 for (i = 0, sp = dp = row; i < row_width; i++)
441 png_byte save = *(sp++);
447 #ifdef PNG_WRITE_16BIT_SUPPORTED
450 /* This converts from AAGG to GGAA */
453 png_uint_32 row_width = row_info->width;
455 for (i = 0, sp = dp = row; i < row_width; i++)
466 #endif /* PNG_WRITE_16BIT_SUPPORTED */
472 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
474 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
476 png_debug(1, "in png_do_write_invert_alpha");
479 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
481 if (row_info->bit_depth == 8)
483 /* This inverts the alpha channel in RGBA */
486 png_uint_32 row_width = row_info->width;
488 for (i = 0, sp = dp = row; i < row_width; i++)
496 *(dp++) = (png_byte)(255 - *(sp++));
500 #ifdef PNG_WRITE_16BIT_SUPPORTED
503 /* This inverts the alpha channel in RRGGBBAA */
506 png_uint_32 row_width = row_info->width;
508 for (i = 0, sp = dp = row; i < row_width; i++)
519 *(dp++) = (png_byte)(255 - *(sp++));
520 *(dp++) = (png_byte)(255 - *(sp++));
523 #endif /* PNG_WRITE_16BIT_SUPPORTED */
526 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
528 if (row_info->bit_depth == 8)
530 /* This inverts the alpha channel in GA */
533 png_uint_32 row_width = row_info->width;
535 for (i = 0, sp = dp = row; i < row_width; i++)
538 *(dp++) = (png_byte)(255 - *(sp++));
542 #ifdef PNG_WRITE_16BIT_SUPPORTED
545 /* This inverts the alpha channel in GGAA */
548 png_uint_32 row_width = row_info->width;
550 for (i = 0, sp = dp = row; i < row_width; i++)
557 *(dp++) = (png_byte)(255 - *(sp++));
558 *(dp++) = (png_byte)(255 - *(sp++));
561 #endif /* PNG_WRITE_16BIT_SUPPORTED */
567 #ifdef PNG_MNG_FEATURES_SUPPORTED
568 /* Undoes intrapixel differencing */
570 png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
572 png_debug(1, "in png_do_write_intrapixel");
574 if ((row_info->color_type & PNG_COLOR_MASK_COLOR))
577 png_uint_32 row_width = row_info->width;
578 if (row_info->bit_depth == 8)
583 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
586 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
592 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
594 *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
595 *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
599 #ifdef PNG_WRITE_16BIT_SUPPORTED
600 else if (row_info->bit_depth == 16)
605 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
608 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
614 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
616 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
617 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
618 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
619 png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
620 png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
621 *(rp ) = (png_byte)((red >> 8) & 0xff);
622 *(rp + 1) = (png_byte)(red & 0xff);
623 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
624 *(rp + 5) = (png_byte)(blue & 0xff);
627 #endif /* PNG_WRITE_16BIT_SUPPORTED */
630 #endif /* PNG_MNG_FEATURES_SUPPORTED */
631 #endif /* PNG_WRITE_SUPPORTED */