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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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16
src/mux/muxedit.c
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@ -218,7 +218,7 @@ static WebPMuxError MuxDeleteAllNamedData(WebPMux* const mux,
if (mux == NULL || name == NULL) return WEBP_MUX_INVALID_ARGUMENT;
if (IsWPI(id)) return WEBP_MUX_INVALID_ARGUMENT;
chunk_list = GetChunkListFromId(mux, id);
chunk_list = MuxGetChunkListFromId(mux, id);
if (chunk_list == NULL) return WEBP_MUX_INVALID_ARGUMENT;
return DeleteChunks(chunk_list, kChunks[idx].tag);
@ -390,7 +390,7 @@ static WebPMuxError MuxAddFrameTileInternal(
image_info = NULL; // Owned by 'chunk' now.
err = ChunkSetNth(&chunk, &wpi.img_, 1);
if (err != WEBP_MUX_OK) goto Err;
ChunkInit(&chunk); // chunk owned by wpi.vp8_ now.
ChunkInit(&chunk); // chunk owned by wpi.img_ now.
// Create frame/tile data from image_info.
err = CreateDataFromImageInfo(wpi.img_->image_info_, is_frame,
@ -452,7 +452,7 @@ WebPMuxError WebPMuxDeleteImage(WebPMux* const mux) {
if (mux == NULL) return WEBP_MUX_INVALID_ARGUMENT;
err = ValidateForImage(mux);
err = MuxValidateForImage(mux);
if (err != WEBP_MUX_OK) return err;
// All well, delete image.
@ -623,6 +623,14 @@ static WebPMuxError CreateVP8XChunk(WebPMux* const mux) {
err = GetImageCanvasWidthHeight(mux, flags, &width, &height);
if (err != WEBP_MUX_OK) return err;
if (MuxHasLosslessImages(images)) {
// We have a file with a VP8X chunk having some lossless images.
// As lossless images implicitly contain alpha, force ALPHA_FLAG to be true.
// Note: This 'flags' update must NOT be done for a lossless image
// without a VP8X chunk!
flags |= ALPHA_FLAG;
}
PutLE32(data + 0, flags); // VP8X chunk flags.
PutLE32(data + 4, width); // canvas width.
PutLE32(data + 8, height); // canvas height.
@ -695,7 +703,7 @@ WebPMuxError WebPMuxAssemble(WebPMux* const mux,
assert(dst == data + size);
// Validate mux.
err = WebPMuxValidate(mux);
err = MuxValidate(mux);
if (err != WEBP_MUX_OK) {
free(data);
data = NULL;