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LibPDF+LibGfx: Pass jbig2-filtered data to JBIG2ImageDecoderPlugin

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Except for /JBIG2Globals, which we bail out on for now. In my 1000
files, 13 use JBIG2, and of those, 2 use JBIG2Globals (0000372.pdf e.g.
page 11 and 0000857.pdf e.g. page 1), and only one (the latter) of the
two uses the same JBIG2Globals stream for more than a single image.

JBIG2ImageDecoderPlugin cannot decode the data yet, so no behavior
change, but with `#define JBIG2_DEBUG 1` at the top of that file,
it now prints segment header info for PDFs containing JBIG2 data :^)
This commit is contained in:
Nico Weber 2024-03-03 21:05:53 -05:00 • committed by Andreas Kling
parent bd60d1db7e
commit 953f6c5d9b
5 changed files with 26 additions and 5 deletions
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13
Userland/Libraries/LibGfx/ImageFormats/JBIG2Loader.cpp
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@ -180,7 +180,10 @@ static ErrorOr<SegmentHeader> decode_segment_header(SeekableStream& stream)
static ErrorOr<void> decode_segment_headers(JBIG2LoadingContext& context)
{
FixedMemoryStream stream(context.data.slice(sizeof(id_string) + sizeof(u8) + (context.number_of_pages.has_value() ? sizeof(u32) : 0)));
ReadonlyBytes data = context.data;
if (context.organization != Organization::Embedded)
data = data.slice(sizeof(id_string) + sizeof(u8) + (context.number_of_pages.has_value() ? sizeof(u32) : 0));
FixedMemoryStream stream(data);
while (!stream.is_eof()) {
auto segment_header = TRY(decode_segment_header(stream));
if (context.organization != Organization::RandomAccess) {
@ -232,4 +235,12 @@ ErrorOr<ImageFrameDescriptor> JBIG2ImageDecoderPlugin::frame(size_t index, Optio
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Draw the rest of the owl");
}
ErrorOr<ByteBuffer> JBIG2ImageDecoderPlugin::decode_embedded(ReadonlyBytes data)
{
auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) JBIG2ImageDecoderPlugin(data)));
plugin->m_context->organization = Organization::Embedded;
TRY(decode_segment_headers(*plugin->m_context));
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Cannot decode embedded JBIG2 yet");
}
}