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Tests/LibGfx: More preparation for lossy and alpha handling

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If someone comes along who wants to implement lossy webp decoding,
they now only need to implement decode_webp_chunk_VP8() and everything
might Just Work.

It also makes it possible to implement alpha chunk decoding before
implementing lossy decoding (by making decode_webp_chunk_VP8()
return an empty black bitmap for testing).
This commit is contained in:
Nico Weber 2023-05-06 16:34:45 -04:00 • committed by Andreas Kling
parent 23386ac73a
commit e9f5c9ab9d
1 changed files with 14 additions and 2 deletions
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16
Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp
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@ -299,6 +299,14 @@ static ErrorOr<VP8Header> decode_webp_chunk_VP8_header(WebPLoadingContext& conte
return VP8Header { version, show_frame, size_of_first_partition, width, horizontal_scale, height, vertical_scale };
}
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8(WebPLoadingContext& context, Chunk const& vp8_chunk)
{
VERIFY(vp8_chunk.type == FourCC("VP8 "));
// FIXME: Implement webp lossy decoding.
return context.error("WebPImageDecoderPlugin: decoding lossy webps not yet implemented");
}
// https://developers.google.com/speed/webp/docs/riff_container#simple_file_format_lossless
// https://developers.google.com/speed/webp/docs/webp_lossless_bitstream_specification#7_overall_structure_of_the_format
static ErrorOr<VP8LHeader> decode_webp_chunk_VP8L_header(WebPLoadingContext& context, Chunk const& vp8l_chunk)
@ -1584,9 +1592,13 @@ static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_image_data(WebPLoadingContext&
}
VERIFY(image_data.image_data_chunk->type == FourCC("VP8 "));
auto bitmap = TRY(decode_webp_chunk_VP8(context, image_data.image_data_chunk.value()));
// FIXME: Implement.
return context.error("WebPImageDecoderPlugin: decoding lossy webps not yet implemented");
if (image_data.alpha_chunk.has_value()) {
// FIXME: Decode alpha chunk and store decoded alpha in `bitmap`.
}
return bitmap;
}
// https://developers.google.com/speed/webp/docs/riff_container#assembling_the_canvas_from_frames