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LibGfx/JBIG2: Sketch out text segment refinement coding a bit

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Nico Weber 2024-03-21 09:46:39 -04:00 committed by Andreas Kling
parent 9f327833c0
commit c4c48c1d5f
Notes: sideshowbarker 2024-07-17 10:08:28 +09:00 
Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/c4c48c1d5f
Pull-request: https://github.com/SerenityOS/serenity/pull/23696
1 changed files with 22 additions and 6 deletions
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28
Userland/Libraries/LibGfx/ImageFormats/JBIG2Loader.cpp
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@ -992,9 +992,6 @@ static ErrorOr<NonnullOwnPtr<BitBuffer>> text_region_decoding_procedure(TextRegi
if (inputs.uses_huffman_encoding)
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Cannot decode huffman text regions yet");
if (inputs.uses_refinement_coding)
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Cannot decode refined text regions yet");
if (inputs.is_transposed)
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Cannot decode transposed text regions yet");
@ -1059,6 +1056,27 @@ static ErrorOr<NonnullOwnPtr<BitBuffer>> text_region_decoding_procedure(TextRegi
return prev;
};
// 6.4.11 Symbol instance bitmap
JBIG2::ArithmeticIntegerDecoder has_refinement_image_decoder(decoder);
auto read_bitmap = [&](u32 id) -> ErrorOr<BitBuffer const*> {
bool has_refinement_image = false; // "R_I" in spec.
if (inputs.uses_refinement_coding) {
// "• If SBHUFF is 1, then read one bit and set RI to the value of that bit.
// • If SBHUFF is 0, then decode one bit using the IARI integer arithmetic decoding procedure and set RI to the value of that bit."
// FIXME: Implement support for SBHUFF = 1.
has_refinement_image = has_refinement_image_decoder.decode().value();
}
if (!has_refinement_image) {
if (id >= inputs.symbols.size())
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Symbol ID out of range");
auto const& symbol = inputs.symbols[id]->bitmap();
return &symbol;
}
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Cannot decode refined text regions yet");
};
// 6.4.5 Decoding the text region
// "1) Fill a bitmap SBREG, of the size given by SBW and SBH, with the SBDEFPIXEL value."
@ -1123,9 +1141,7 @@ static ErrorOr<NonnullOwnPtr<BitBuffer>> text_region_decoding_procedure(TextRegi
// "v) Determine the symbol instance's bitmap IBI as described in 6.4.11. The width and height of this
// bitmap shall be denoted as WI and HI respectively."
if (id >= inputs.symbols.size())
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Symbol ID out of range");
auto const& symbol = inputs.symbols[id]->bitmap();
auto const& symbol = *TRY(read_bitmap(id));
// "vi) Update CURS as follows:
// • If TRANSPOSED is 0, and REFCORNER is TOPRIGHT or BOTTOMRIGHT, set: