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rsvg: Unpremultiply Cairo's ARGB to match GStreamer's

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This commit is contained in:
Sebastian Dröge 2009-10-01 10:54:15 +02:00
parent 05e059c624
commit f760ad2dfc
1 changed files with 34 additions and 0 deletions
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34
ext/rsvg/gstrsvgdec.c
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@ -144,6 +144,36 @@ gst_rsvg_dec_reset (GstRsvgDec * dec)
}
}
#define CAIRO_UNPREMULTIPLY(a,r,g,b) G_STMT_START { \
b = (a > 0) ? MIN ((b * 255 + a / 2) / a, 255) : 0; \
g = (a > 0) ? MIN ((g * 255 + a / 2) / a, 255) : 0; \
r = (a > 0) ? MIN ((r * 255 + a / 2) / a, 255) : 0; \
} G_STMT_END
static void
gst_rsvg_decode_unpremultiply (guint8 * data, gint width, gint height)
{
gint i, j;
guint a;
for (i = 0; i < height; i++) {
for (j = 0; j < width; j++) {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
a = data[3];
data[0] = (a > 0) ? MIN ((data[0] * 255 + a / 2) / a, 255) : 0;
data[1] = (a > 0) ? MIN ((data[1] * 255 + a / 2) / a, 255) : 0;
data[2] = (a > 0) ? MIN ((data[2] * 255 + a / 2) / a, 255) : 0;
#else
a = data[0];
data[1] = (a > 0) ? MIN ((data[1] * 255 + a / 2) / a, 255) : 0;
data[2] = (a > 0) ? MIN ((data[2] * 255 + a / 2) / a, 255) : 0;
data[3] = (a > 0) ? MIN ((data[3] * 255 + a / 2) / a, 255) : 0;
#endif
data += 4;
}
}
}
static GstFlowReturn
gst_rsvg_decode_image (GstRsvgDec * rsvg, const guint8 * data, guint size,
GstBuffer ** buffer)
@ -274,6 +304,10 @@ gst_rsvg_decode_image (GstRsvgDec * rsvg, const guint8 * data, guint size,
cairo_destroy (cr);
cairo_surface_destroy (surface);
/* Now unpremultiply Cairo's ARGB to match GStreamer's */
gst_rsvg_decode_unpremultiply (GST_BUFFER_DATA (*buffer), rsvg->width,
rsvg->height);
return ret;
}