| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * PNG image format | ||
| 3 | * Copyright (c) 2003 Fabrice Bellard | ||
| 4 | * | ||
| 5 | * This file is part of FFmpeg. | ||
| 6 | * | ||
| 7 | * FFmpeg is free software; you can redistribute it and/or | ||
| 8 | * modify it under the terms of the GNU Lesser General Public | ||
| 9 | * License as published by the Free Software Foundation; either | ||
| 10 | * version 2.1 of the License, or (at your option) any later version. | ||
| 11 | * | ||
| 12 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| 15 | * Lesser General Public License for more details. | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU Lesser General Public | ||
| 18 | * License along with FFmpeg; if not, write to the Free Software | ||
| 19 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | ||
| 20 | */ | ||
| 21 | |||
| 22 | #include <stdint.h> | ||
| 23 | #include "libavutil/mem.h" | ||
| 24 | #include "png.h" | ||
| 25 | |||
| 26 | /* Mask to determine which y pixels are valid in a pass */ | ||
| 27 | const uint8_t ff_png_pass_ymask[NB_PASSES] = { | ||
| 28 | 0x80, 0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, | ||
| 29 | }; | ||
| 30 | |||
| 31 | /* minimum x value */ | ||
| 32 | static const uint8_t ff_png_pass_xmin[NB_PASSES] = { | ||
| 33 | 0, 4, 0, 2, 0, 1, 0 | ||
| 34 | }; | ||
| 35 | |||
| 36 | /* x shift to get row width */ | ||
| 37 | static const uint8_t ff_png_pass_xshift[NB_PASSES] = { | ||
| 38 | 3, 3, 2, 2, 1, 1, 0 | ||
| 39 | }; | ||
| 40 | |||
| 41 | 672 | int ff_png_get_nb_channels(int color_type) | |
| 42 | { | ||
| 43 | int channels; | ||
| 44 | 672 | channels = 1; | |
| 45 |
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672 | if ((color_type & (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)) == |
| 46 | PNG_COLOR_MASK_COLOR) | ||
| 47 | 605 | channels = 3; | |
| 48 |
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672 | if (color_type & PNG_COLOR_MASK_ALPHA) |
| 49 | 105 | channels++; | |
| 50 | 672 | return channels; | |
| 51 | } | ||
| 52 | |||
| 53 | /* compute the row size of an interleaved pass */ | ||
| 54 | 56 | int ff_png_pass_row_size(int pass, int bits_per_pixel, int width) | |
| 55 | { | ||
| 56 | int shift, xmin, pass_width; | ||
| 57 | |||
| 58 | 56 | xmin = ff_png_pass_xmin[pass]; | |
| 59 |
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56 | if (width <= xmin) |
| 60 | ✗ | return 0; | |
| 61 | 56 | shift = ff_png_pass_xshift[pass]; | |
| 62 | 56 | pass_width = (width - xmin + (1 << shift) - 1) >> shift; | |
| 63 | 56 | return (pass_width * bits_per_pixel + 7) >> 3; | |
| 64 | } | ||
| 65 |