ffmpeg-2.8.5

git-svn-id: svn://kolibrios.org@6147 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/sdk/sources/ffmpeg/ffmpeg-2.8/libavcodec/png.c

@@ -0,0 +1,72 @@
+/*
+ * 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 "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_mallocz_array(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;
+}