/* * 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 <stdint.h> #include "libavutil/mem.h" #include "png.h" /* 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 */ static const uint8_t ff_png_pass_xmin[NB_PASSES] = { 0, 4, 0, 2, 0, 1, 0 }; /* x shift to get row width */ static const uint8_t ff_png_pass_xshift[NB_PASSES] = { 3, 3, 2, 2, 1, 1, 0 }; void *ff_png_zalloc(void *opaque, unsigned int items, unsigned int size) { return av_calloc(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; }