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Alpha flag fix for lossless.

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- Make sure alpha flag is set in case of a lossless file with VP8X chunk.
  The semantic of ALPHA_FLAG changes with this: it means the images
  contain alpha (rather than ALPH chunk in particular).
- Update the mux container spec to add 1-line description of alpha
  flag.
- Rename "HasLosslessImages()" to "MuxHasLosslessImages()", and other
  similar function renames.
- Rename FeatureFlags to WebPFeatureFlags
- Elaborated a comment for a special case.
- A misc comment fix.

Change-Id: If212ccf4338c125b4c71c10bf281a51b3ba7ff45
This commit is contained in:
Urvang Joshi
2012-05-23 15:01:25 +05:30
parent 98ec717f1e
commit c975c44ea5
6 changed files with 60 additions and 28 deletions
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39
src/mux/muxinternal.c
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@ -422,10 +422,21 @@ uint8_t* MuxImageListEmit(const WebPMuxImage* wpi_list, uint8_t* dst) {
return dst;
}
int MuxHasLosslessImages(const WebPMuxImage* images) {
while (images != NULL) {
assert(images->img_ != NULL);
if (images->img_->tag_ == kChunks[IDX_VP8L].tag) {
return 1;
}
images = images->next_;
}
return 0;
}
//------------------------------------------------------------------------------
// Helper methods for mux.
WebPChunk** GetChunkListFromId(const WebPMux* mux, TAG_ID id) {
WebPChunk** MuxGetChunkListFromId(const WebPMux* mux, TAG_ID id) {
assert(mux != NULL);
switch(id) {
case VP8X_ID: return (WebPChunk**)&mux->vp8x_;
@ -437,7 +448,7 @@ WebPChunk** GetChunkListFromId(const WebPMux* mux, TAG_ID id) {
}
}
WebPMuxError ValidateForImage(const WebPMux* const mux) {
WebPMuxError MuxValidateForImage(const WebPMux* const mux) {
const int num_images = MuxImageCount(mux->images_, IMAGE_ID);
const int num_frames = MuxImageCount(mux->images_, FRAME_ID);
const int num_tiles = MuxImageCount(mux->images_, TILE_ID);
@ -465,7 +476,8 @@ static int IsNotCompatible(int feature, int num_items) {
// and feature incompatibility (use NO_FLAG to skip).
// On success returns WEBP_MUX_OK and stores the chunk count in *num.
static WebPMuxError ValidateChunk(const WebPMux* const mux, CHUNK_INDEX idx,
FeatureFlags feature, FeatureFlags vp8x_flags,
WebPFeatureFlags feature,
WebPFeatureFlags vp8x_flags,
int max, int* num) {
const WebPMuxError err =
WebPMuxNumNamedElements(mux, kChunks[idx].name, num);
@ -477,7 +489,7 @@ static WebPMuxError ValidateChunk(const WebPMux* const mux, CHUNK_INDEX idx,
return WEBP_MUX_OK;
}
WebPMuxError WebPMuxValidate(const WebPMux* const mux) {
WebPMuxError MuxValidate(const WebPMux* const mux) {
int num_iccp;
int num_meta;
int num_loop_chunks;
@ -541,14 +553,19 @@ WebPMuxError WebPMuxValidate(const WebPMux* const mux) {
if (num_vp8x == 0 && num_images != 1) return WEBP_MUX_INVALID_ARGUMENT;
// ALPHA_FLAG & alpha chunk(s) are consistent.
err = ValidateChunk(mux, IDX_ALPHA, ALPHA_FLAG, flags, -1, &num_alpha);
if (err != WEBP_MUX_OK) return err;
if (num_vp8x > 0 && MuxHasLosslessImages(mux->images_)) {
// Special case: we have a VP8X chunk as well as some lossless images.
if (!(flags & ALPHA_FLAG)) return WEBP_MUX_INVALID_ARGUMENT;
} else {
err = ValidateChunk(mux, IDX_ALPHA, ALPHA_FLAG, flags, -1, &num_alpha);
if (err != WEBP_MUX_OK) return err;
// num_images & num_alpha_chunks are consistent.
if (num_alpha > 0 && num_alpha != num_images) {
// Note that "num_alpha > 0" is the correct check but "flags && ALPHA_FLAG"
// is NOT, because ALPHA_FLAG is based on first image only.
return WEBP_MUX_INVALID_ARGUMENT;
// num_images & num_alpha_chunks are consistent.
if (num_alpha > 0 && num_alpha != num_images) {
// Note that "num_alpha > 0" is the correct test but "flags && ALPHA_FLAG"
// is NOT, because ALPHA_FLAG is based on first image only.
return WEBP_MUX_INVALID_ARGUMENT;
}
}
// num_tiles & num_images are consistent.