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add colorspace for premultiplied alpha

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The new modes are
       MODE_rgbA
       MODE_bgrA
       MODE_Argb
       MODE_rgbA_4444
It's binary incompatible, since the enums changed.

While at it, i removed the now unneeded KeepAlpha methods.
-> Saved ~12k of code!

* made explicit mention that alpha_plane is persistent,
so we have access to the full alpha plane data at all time.
Incremental decoding of alpha was planned for, but not
implemented. So better not dragged this constaint for now
and make the code easier until we revisit that.

Change-Id: Idaba281a6ca819965ca062d1c23329f36d90c7ff
This commit is contained in:
Pascal Massimino
2012-06-04 07:40:32 -07:00
parent 5f7bb3f53a
commit 48f827574e
13 changed files with 303 additions and 122 deletions
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14
src/dec/frame.c
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@ -200,7 +200,12 @@ static int FinishRow(VP8Decoder* const dec, VP8Io* const io) {
y_end = io->crop_bottom; // make sure we don't overflow on last row.
}
io->a = NULL;
if (dec->alpha_data_ && y_start < y_end) {
if (dec->alpha_data_ != NULL && y_start < y_end) {
// TODO(skal): several things to correct here:
// * testing presence of alpha with dec->alpha_data_ is not a good idea
// * we're actually decompressing the full plane only once. It should be
// more obvious from signature.
// * we could free alpha_data_ right after this call, but we don't own.
io->a = VP8DecompressAlphaRows(dec, y_start, y_end - y_start);
if (io->a == NULL) {
return VP8SetError(dec, VP8_STATUS_BITSTREAM_ERROR,
@ -214,7 +219,7 @@ static int FinishRow(VP8Decoder* const dec, VP8Io* const io) {
io->y += dec->cache_y_stride_ * delta_y;
io->u += dec->cache_uv_stride_ * (delta_y >> 1);
io->v += dec->cache_uv_stride_ * (delta_y >> 1);
if (io->a) {
if (io->a != NULL) {
io->a += io->width * delta_y;
}
}
@ -222,7 +227,7 @@ static int FinishRow(VP8Decoder* const dec, VP8Io* const io) {
io->y += io->crop_left;
io->u += io->crop_left >> 1;
io->v += io->crop_left >> 1;
if (io->a) {
if (io->a != NULL) {
io->a += io->crop_left;
}
io->mb_y = y_start - io->crop_top;
@ -417,7 +422,8 @@ static int AllocateMemory(VP8Decoder* const dec) {
+ kFilterExtraRows[dec->filter_type_]) * 3 / 2;
const size_t cache_size = top_size * cache_height;
const size_t alpha_size =
dec->alpha_data_ ? (dec->pic_hdr_.width_ * dec->pic_hdr_.height_) : 0;
(dec->alpha_data_ != NULL) ? dec->pic_hdr_.width_ * dec->pic_hdr_.height_
: 0;
const size_t needed = intra_pred_mode_size
+ top_size + mb_info_size + f_info_size
+ yuv_size + coeffs_size