2 /* pngwtran.c - transforms the data in a row for PNG writers
4 * Copyright (c) 2018 Cosmin Truta
5 * Copyright (c) 1998-2002,2004,2006-2016,2018 Glenn Randers-Pehrson
6 * Copyright (c) 1996-1997 Andreas Dilger
7 * 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
17 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
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).
25 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
27 png_debug(1, "in png_do_pack");
29 if (row_info->bit_depth == 8 &&
30 row_info->channels == 1)
32 switch ((int)bit_depth)
39 png_uint_32 row_width = row_info->width;
46 for (i = 0; i < row_width; i++)
77 png_uint_32 row_width = row_info->width;
84 for (i = 0; i < row_width; i++)
88 value = (png_byte)(*sp & 0x03);
89 v |= (value << shift);
117 png_uint_32 row_width = row_info->width;
124 for (i = 0; i < row_width; i++)
128 value = (png_byte)(*sp & 0x0f);
129 v |= (value << shift);
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,
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
172 png_do_shift(png_row_infop row_info, png_bytep row,
173 png_const_color_8p bit_depth)
175 png_debug(1, "in png_do_shift");
177 if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
179 int shift_start[4], shift_dec[4];
180 unsigned int channels = 0;
182 if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
184 shift_start[channels] = row_info->bit_depth - bit_depth->red;
185 shift_dec[channels] = bit_depth->red;
188 shift_start[channels] = row_info->bit_depth - bit_depth->green;
189 shift_dec[channels] = bit_depth->green;
192 shift_start[channels] = row_info->bit_depth - bit_depth->blue;
193 shift_dec[channels] = bit_depth->blue;
199 shift_start[channels] = row_info->bit_depth - bit_depth->gray;
200 shift_dec[channels] = bit_depth->gray;
204 if ((row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0)
206 shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
207 shift_dec[channels] = bit_depth->alpha;
211 /* With low row depths, could only be grayscale, so one channel */
212 if (row_info->bit_depth < 8)
217 size_t row_bytes = row_info->rowbytes;
219 if (bit_depth->gray == 1 && row_info->bit_depth == 2)
222 else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
228 for (i = 0; i < row_bytes; i++, bp++)
236 for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
242 out |= (v >> (-j)) & mask;
245 *bp = (png_byte)(out & 0xff);
249 else if (row_info->bit_depth == 8)
253 png_uint_32 istop = channels * row_info->width;
255 for (i = 0; i < istop; i++, bp++)
257 unsigned int c = i%channels;
264 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
273 *bp = (png_byte)(out & 0xff);
281 png_uint_32 istop = channels * row_info->width;
283 for (bp = row, i = 0; i < istop; i++)
285 unsigned int c = i%channels;
287 unsigned int value, v;
289 v = png_get_uint_16(bp);
292 for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
300 *bp++ = (png_byte)((value >> 8) & 0xff);
301 *bp++ = (png_byte)(value & 0xff);
308 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
310 png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
312 png_debug(1, "in png_do_write_swap_alpha");
315 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
317 if (row_info->bit_depth == 8)
319 /* This converts from ARGB to RGBA */
322 png_uint_32 row_width = row_info->width;
324 for (i = 0, sp = dp = row; i < row_width; i++)
326 png_byte save = *(sp++);
334 #ifdef PNG_WRITE_16BIT_SUPPORTED
337 /* This converts from AARRGGBB to RRGGBBAA */
340 png_uint_32 row_width = row_info->width;
342 for (i = 0, sp = dp = row; i < row_width; i++)
357 #endif /* WRITE_16BIT */
360 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
362 if (row_info->bit_depth == 8)
364 /* This converts from AG to GA */
367 png_uint_32 row_width = row_info->width;
369 for (i = 0, sp = dp = row; i < row_width; i++)
371 png_byte save = *(sp++);
377 #ifdef PNG_WRITE_16BIT_SUPPORTED
380 /* This converts from AAGG to GGAA */
383 png_uint_32 row_width = row_info->width;
385 for (i = 0, sp = dp = row; i < row_width; i++)
396 #endif /* WRITE_16BIT */
402 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
404 png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
406 png_debug(1, "in png_do_write_invert_alpha");
409 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
411 if (row_info->bit_depth == 8)
413 /* This inverts the alpha channel in RGBA */
416 png_uint_32 row_width = row_info->width;
418 for (i = 0, sp = dp = row; i < row_width; i++)
426 *dp = (png_byte)(255 - *(sp++));
430 #ifdef PNG_WRITE_16BIT_SUPPORTED
433 /* This inverts the alpha channel in RRGGBBAA */
436 png_uint_32 row_width = row_info->width;
438 for (i = 0, sp = dp = row; i < row_width; i++)
449 *(dp++) = (png_byte)(255 - *(sp++));
450 *dp = (png_byte)(255 - *(sp++));
453 #endif /* WRITE_16BIT */
456 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
458 if (row_info->bit_depth == 8)
460 /* This inverts the alpha channel in GA */
463 png_uint_32 row_width = row_info->width;
465 for (i = 0, sp = dp = row; i < row_width; i++)
468 *(dp++) = (png_byte)(255 - *(sp++));
472 #ifdef PNG_WRITE_16BIT_SUPPORTED
475 /* This inverts the alpha channel in GGAA */
478 png_uint_32 row_width = row_info->width;
480 for (i = 0, sp = dp = row; i < row_width; i++)
487 *(dp++) = (png_byte)(255 - *(sp++));
488 *dp = (png_byte)(255 - *(sp++));
491 #endif /* WRITE_16BIT */
497 /* Transform the data according to the user's wishes. The order of
498 * transformations is significant.
501 png_do_write_transformations(png_structrp png_ptr, png_row_infop row_info)
503 png_debug(1, "in png_do_write_transformations");
508 #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
509 if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
510 if (png_ptr->write_user_transform_fn != NULL)
511 (*(png_ptr->write_user_transform_fn)) /* User write transform
513 (png_ptr, /* png_ptr */
514 row_info, /* row_info: */
515 /* png_uint_32 width; width of row */
516 /* size_t rowbytes; number of bytes in row */
517 /* png_byte color_type; color type of pixels */
518 /* png_byte bit_depth; bit depth of samples */
519 /* png_byte channels; number of channels (1-4) */
520 /* png_byte pixel_depth; bits per pixel (depth*channels) */
521 png_ptr->row_buf + 1); /* start of pixel data for row */
524 #ifdef PNG_WRITE_FILLER_SUPPORTED
525 if ((png_ptr->transformations & PNG_FILLER) != 0)
526 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
527 !(png_ptr->flags & PNG_FLAG_FILLER_AFTER));
530 #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
531 if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
532 png_do_packswap(row_info, png_ptr->row_buf + 1);
535 #ifdef PNG_WRITE_PACK_SUPPORTED
536 if ((png_ptr->transformations & PNG_PACK) != 0)
537 png_do_pack(row_info, png_ptr->row_buf + 1,
538 (png_uint_32)png_ptr->bit_depth);
541 #ifdef PNG_WRITE_SWAP_SUPPORTED
542 # ifdef PNG_16BIT_SUPPORTED
543 if ((png_ptr->transformations & PNG_SWAP_BYTES) != 0)
544 png_do_swap(row_info, png_ptr->row_buf + 1);
548 #ifdef PNG_WRITE_SHIFT_SUPPORTED
549 if ((png_ptr->transformations & PNG_SHIFT) != 0)
550 png_do_shift(row_info, png_ptr->row_buf + 1,
554 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
555 if ((png_ptr->transformations & PNG_SWAP_ALPHA) != 0)
556 png_do_write_swap_alpha(row_info, png_ptr->row_buf + 1);
559 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
560 if ((png_ptr->transformations & PNG_INVERT_ALPHA) != 0)
561 png_do_write_invert_alpha(row_info, png_ptr->row_buf + 1);
564 #ifdef PNG_WRITE_BGR_SUPPORTED
565 if ((png_ptr->transformations & PNG_BGR) != 0)
566 png_do_bgr(row_info, png_ptr->row_buf + 1);
569 #ifdef PNG_WRITE_INVERT_SUPPORTED
570 if ((png_ptr->transformations & PNG_INVERT_MONO) != 0)
571 png_do_invert(row_info, png_ptr->row_buf + 1);
574 #endif /* WRITE_TRANSFORMS */