fix rescaling bug: alpha plane wasn't filled with 0xff
(in case no alpha was present in the source .webp,
but user requested some)
Change-Id: I9011d38237907c60d6796a86bd2c72166aa80f27
diff --git a/src/dec/io.c b/src/dec/io.c
index 13e469a..8d5c43f 100644
--- a/src/dec/io.c
+++ b/src/dec/io.c
@@ -119,6 +119,14 @@
//------------------------------------------------------------------------------
+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 @@
}
} 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 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 @@
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;
}
