| /* |
| * PNG image format |
| * Copyright (c) 2003 Fabrice Bellard |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| #include "avcodec.h" |
| #include "bytestream.h" |
| #include "png.h" |
| |
| const uint8_t ff_pngsig[8] = {137, 80, 78, 71, 13, 10, 26, 10}; |
| const uint8_t ff_mngsig[8] = {138, 77, 78, 71, 13, 10, 26, 10}; |
| |
| /* Mask to determine which y pixels are valid in a pass */ |
| const uint8_t ff_png_pass_ymask[NB_PASSES] = { |
| 0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, |
| }; |
| |
| /* minimum x value */ |
| const uint8_t ff_png_pass_xmin[NB_PASSES] = { |
| 0, 4, 0, 2, 0, 1, 0 |
| }; |
| |
| /* x shift to get row width */ |
| const uint8_t ff_png_pass_xshift[NB_PASSES] = { |
| 3, 3, 2, 2, 1, 1, 0 |
| }; |
| |
| /* Mask to determine which pixels are valid in a pass */ |
| const uint8_t ff_png_pass_mask[NB_PASSES] = { |
| 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff |
| }; |
| |
| void *ff_png_zalloc(void *opaque, unsigned int items, unsigned int size) |
| { |
| if(items >= UINT_MAX / size) |
| return NULL; |
| return av_malloc(items * size); |
| } |
| |
| void ff_png_zfree(void *opaque, void *ptr) |
| { |
| av_free(ptr); |
| } |
| |
| int ff_png_get_nb_channels(int color_type) |
| { |
| int channels; |
| channels = 1; |
| if ((color_type & (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)) == |
| PNG_COLOR_MASK_COLOR) |
| channels = 3; |
| if (color_type & PNG_COLOR_MASK_ALPHA) |
| channels++; |
| return channels; |
| } |
| |
| /* compute the row size of an interleaved pass */ |
| int ff_png_pass_row_size(int pass, int bits_per_pixel, int width) |
| { |
| int shift, xmin, pass_width; |
| |
| xmin = ff_png_pass_xmin[pass]; |
| if (width <= xmin) |
| return 0; |
| shift = ff_png_pass_xshift[pass]; |
| pass_width = (width - xmin + (1 << shift) - 1) >> shift; |
| return (pass_width * bits_per_pixel + 7) >> 3; |
| } |