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fix rescaling bug: alpha plane wasn't filled with 0xff

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(in case no alpha was present in the source .webp,
but user requested some)

Change-Id: I9011d38237907c60d6796a86bd2c72166aa80f27
(cherry picked from commit 06a38c7b1c)
This commit is contained in:
Pascal Massimino 2016-06-24 17:15:31 +02:00 committed by James Zern
parent 6a19793777
commit f918cb1013
1 changed files with 15 additions and 5 deletions
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20
src/dec/io.c
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@ -119,6 +119,14 @@ static int EmitFancyRGB(const VP8Io* const io, WebPDecParams* const p) {
//------------------------------------------------------------------------------
static void FillAlphaPlane(uint8_t* dst, int w, int h, int stride) {
int j;
for (j = 0; j < h; ++j) {
memset(dst, 0xff, w * sizeof(*dst));
dst += stride;
}
}
static int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p,
int expected_num_lines_out) {
const uint8_t* alpha = io->a;
@ -137,10 +145,7 @@ static int EmitAlphaYUV(const VP8Io* const io, WebPDecParams* const p,
}
} else if (buf->a != NULL) {
// the user requested alpha, but there is none, set it to opaque.
for (j = 0; j < mb_h; ++j) {
memset(dst, 0xff, mb_w * sizeof(*dst));
dst += buf->a_stride;
}
FillAlphaPlane(dst, mb_w, mb_h, buf->a_stride);
}
return 0;
}
@ -269,8 +274,8 @@ static int EmitRescaledYUV(const VP8Io* const io, WebPDecParams* const p) {
static int EmitRescaledAlphaYUV(const VP8Io* const io, WebPDecParams* const p,
int expected_num_lines_out) {
const WebPYUVABuffer* const buf = &p->output->u.YUVA;
if (io->a != NULL) {
const WebPYUVABuffer* const buf = &p->output->u.YUVA;
uint8_t* dst_y = buf->y + p->last_y * buf->y_stride;
const uint8_t* src_a = buf->a + p->last_y * buf->a_stride;
const int num_lines_out = Rescale(io->a, io->width, io->mb_h, &p->scaler_a);
@ -280,6 +285,11 @@ static int EmitRescaledAlphaYUV(const VP8Io* const io, WebPDecParams* const p,
WebPMultRows(dst_y, buf->y_stride, src_a, buf->a_stride,
p->scaler_a.dst_width, num_lines_out, 1);
}
} else if (buf->a != NULL) {
// the user requested alpha, but there is none, set it to opaque.
assert(p->last_y + expected_num_lines_out <= io->scaled_height);
FillAlphaPlane(buf->a + p->last_y * buf->a_stride,
io->scaled_width, expected_num_lines_out, buf->a_stride);
}
return 0;
}