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LibGfx/WebP: Store pointer to lossless data in VP8LHeader struct

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This way, the size of the header in bytes is only known in
decode_webp_chunk_VP8L_header().
This commit is contained in:
Nico Weber 2023-05-07 11:21:03 -04:00 • committed by Andreas Kling
parent 5252f1cd60
commit 9d4da5af43
1 changed files with 8 additions and 8 deletions
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16
Userland/Libraries/LibGfx/ImageFormats/WebPLoader.cpp
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@ -71,6 +71,7 @@ struct VP8LHeader {
u16 width;
u16 height;
bool is_alpha_used;
ReadonlyBytes lossless_data;
};
struct VP8XHeader {
@ -344,7 +345,7 @@ static ErrorOr<VP8LHeader> decode_webp_chunk_VP8L_header(Chunk const& vp8l_chunk
if (version_number != 0)
return Error::from_string_literal("WebPImageDecoderPlugin: VP8L chunk invalid version_number");
return VP8LHeader { width, height, is_alpha_used };
return VP8LHeader { width, height, is_alpha_used, vp8l_chunk.data.slice(5) };
}
namespace {
@ -1228,7 +1229,7 @@ ErrorOr<NonnullRefPtr<Bitmap>> ColorIndexingTransform::transform(NonnullRefPtr<B
// 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<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_contents(VP8LHeader const& vp8l_header, ReadonlyBytes lossless_data);
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_contents(VP8LHeader const& vp8l_header);
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L(WebPLoadingContext& context, Chunk const& vp8l_chunk)
{
@ -1236,14 +1237,13 @@ static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L(WebPLoadingContext&
VERIFY(vp8l_chunk.type == FourCC("VP8L"));
auto vp8l_header = TRY(decode_webp_chunk_VP8L_header(vp8l_chunk));
ReadonlyBytes lossless_data = vp8l_chunk.data.slice(5);
return decode_webp_chunk_VP8L_contents(vp8l_header, lossless_data);
return decode_webp_chunk_VP8L_contents(vp8l_header);
}
// Decodes the lossless webp bitstream following the 5-byte header information.
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_contents(VP8LHeader const& vp8l_header, ReadonlyBytes lossless_data)
static ErrorOr<NonnullRefPtr<Bitmap>> decode_webp_chunk_VP8L_contents(VP8LHeader const& vp8l_header)
{
FixedMemoryStream memory_stream { lossless_data };
FixedMemoryStream memory_stream { vp8l_header.lossless_data };
LittleEndianInputBitStream bit_stream { MaybeOwned<Stream>(memory_stream) };
// image-stream = optional-transform spatially-coded-image
@ -1346,8 +1346,8 @@ static ErrorOr<void> decode_webp_chunk_ALPH(WebPLoadingContext& context, Chunk c
// of implicit dimension width x height. That is, this image-stream does NOT contain any headers describing the image dimension.
// Once the image-stream is decoded into ARGB color values, following the process described in the lossless format specification,
// the transparency information must be extracted from the green channel of the ARGB quadruplet."
VP8LHeader vp8l_header = { static_cast<u16>(bitmap.width()), static_cast<u16>(bitmap.height()), /*is_alpha_used=*/false };
auto lossless_bitmap = TRY(decode_webp_chunk_VP8L_contents(vp8l_header, alpha_data));
VP8LHeader vp8l_header { static_cast<u16>(bitmap.width()), static_cast<u16>(bitmap.height()), /*is_alpha_used=*/false, alpha_data };
auto lossless_bitmap = TRY(decode_webp_chunk_VP8L_contents(vp8l_header));
if (pixel_count != static_cast<size_t>(lossless_bitmap->width() * lossless_bitmap->height()))
return context.error("WebPImageDecoderPlugin: decompressed ALPH dimensions don't match VP8 dimensions");