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LibGfx+Tests: Add test for webp ICC loading and fix bug

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I drew the two webp files in Photoshop and saved them using the
"Save a Copy..." dialog, with ICC profile and all other boxes checked.

(I also tried saving with all the boxes unchecked, but it still wrote an
extended webp instead of a basic file.)

The lossless file exposed a bug: I didn't handle chunk padding
correctly before this patch.
This commit is contained in:
Nico Weber 2023-02-24 14:04:21 -05:00 • committed by Linus Groh
parent 7485521619
commit 14c0bae704
4 changed files with 45 additions and 0 deletions
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20
Userland/Libraries/LibGfx/WebPLoader.cpp
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@ -110,6 +110,7 @@ static ErrorOr<void> decode_webp_header(WebPLoadingContext& context)
return {};
}
// https://developers.google.com/speed/webp/docs/riff_container#riff_file_format
static ErrorOr<Chunk> decode_webp_chunk_header(WebPLoadingContext& context, ReadonlyBytes chunks)
{
if (chunks.size() < sizeof(ChunkHeader)) {
@ -128,10 +129,29 @@ static ErrorOr<Chunk> decode_webp_chunk_header(WebPLoadingContext& context, Read
return Chunk { header.chunk_type, { chunks.data() + sizeof(ChunkHeader), header.chunk_size } };
}
// https://developers.google.com/speed/webp/docs/riff_container#riff_file_format
static ErrorOr<Chunk> decode_webp_advance_chunk(WebPLoadingContext& context, ReadonlyBytes& chunks)
{
auto chunk = TRY(decode_webp_chunk_header(context, chunks));
// "Chunk Size: 32 bits (uint32)
// The size of the chunk in bytes, not including this field, the chunk identifier or padding.
// Chunk Payload: Chunk Size bytes
// The data payload. If Chunk Size is odd, a single padding byte -- that MUST be 0 to conform with RIFF -- is added."
chunks = chunks.slice(sizeof(ChunkHeader) + chunk.data.size());
if (chunk.data.size() % 2 != 0) {
if (chunks.is_empty()) {
context.state = WebPLoadingContext::State::Error;
return Error::from_string_literal("Missing data for padding byte");
}
if (*chunks.data() != 0) {
context.state = WebPLoadingContext::State::Error;
return Error::from_string_literal("Padding byte is not 0");
}
chunks = chunks.slice(1);
}
return chunk;
}