RGBCube/serenity
1
Fork 0
mirror of https://github.com/RGBCube/serenity synced 2025-05-31 11:28:12 +00:00
Code Issues Activity Actions

LibGfx: Read transform type in webp lossless decoder

Browse source 
Doesn't do anything with it yet, so this only makes the
"not yet implemented" message a bit more detailed.
This commit is contained in:
Nico Weber 2023-04-03 19:31:41 -04:00 • committed by Linus Groh
parent 8e6911c8f6
commit e8f5e699fe
1 changed files with 32 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

34
Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp
View file

@ -463,8 +463,38 @@ static ErrorOr<void> decode_webp_chunk_VP8L(WebPLoadingContext& context, Chunk c
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#72_structure_of_transforms
// optional-transform = (%b1 transform optional-transform) / %b0
if (TRY(bit_stream.read_bits(1)))
return context.error("WebPImageDecoderPlugin: VP8L transform handling not yet implemented");
while (TRY(bit_stream.read_bits(1))) {
// transform = predictor-tx / color-tx / subtract-green-tx
// transform =/ color-indexing-tx
enum TransformType {
// predictor-tx = %b00 predictor-image
PREDICTOR_TRANSFORM = 0,
// color-tx = %b01 color-image
COLOR_TRANSFORM = 1,
// subtract-green-tx = %b10
SUBTRACT_GREEN_TRANSFORM = 2,
// color-indexing-tx = %b11 color-indexing-image
COLOR_INDEXING_TRANSFORM = 3,
};
TransformType transform_type = static_cast<TransformType>(TRY(bit_stream.read_bits(2)));
dbgln_if(WEBP_DEBUG, "transform type {}", (int)transform_type);
switch (transform_type) {
case PREDICTOR_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L PREDICTOR_TRANSFORM handling not yet implemented");
case COLOR_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L COLOR_TRANSFORM handling not yet implemented");
case SUBTRACT_GREEN_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L SUBTRACT_GREEN_TRANSFORM handling not yet implemented");
case COLOR_INDEXING_TRANSFORM:
return context.error("WebPImageDecoderPlugin: VP8L COLOR_INDEXING_TRANSFORM handling not yet implemented");
}
}
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#623_decoding_entropy-coded_image_data
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#523_color_cache_coding