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LibGfx/JBIG2: Implement pattern_dictionary_decoding_procedure()

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A pattern dictionary stores n bitmaps with the same dimensions w x h.
They're stored in a single bitmap of width `n * w` that's then cut
into n stripes.
This commit is contained in:
Nico Weber 2024-04-02 21:53:18 -07:00 • committed by Andreas Kling
parent d27722ee00
commit ca5b06cc4f
Notes: sideshowbarker 2024-07-17 08:35:21 +09:00
1 changed files with 69 additions and 6 deletions
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75
Userland/Libraries/LibGfx/ImageFormats/JBIG2Loader.cpp
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@ -416,6 +416,8 @@ public:
void set_bit(size_t x, size_t y, bool b);
void fill(bool b);
ErrorOr<NonnullOwnPtr<BitBuffer>> subbitmap(Gfx::IntRect const& rect) const;
ErrorOr<NonnullRefPtr<Gfx::Bitmap>> to_gfx_bitmap() const;
ErrorOr<ByteBuffer> to_byte_buffer() const;
@ -471,6 +473,23 @@ void BitBuffer::fill(bool b)
byte = fill_byte;
}
ErrorOr<NonnullOwnPtr<BitBuffer>> BitBuffer::subbitmap(Gfx::IntRect const& rect) const
{
VERIFY(rect.x() >= 0);
VERIFY(rect.width() >= 0);
VERIFY(static_cast<size_t>(rect.right()) <= width());
VERIFY(rect.y() >= 0);
VERIFY(rect.height() >= 0);
VERIFY(static_cast<size_t>(rect.bottom()) <= height());
auto subbitmap = TRY(create(rect.width(), rect.height()));
for (int y = 0; y < rect.height(); ++y)
for (int x = 0; x < rect.width(); ++x)
subbitmap->set_bit(x, y, get_bit(rect.x() + x, rect.y() + y));
return subbitmap;
}
ErrorOr<NonnullRefPtr<Gfx::Bitmap>> BitBuffer::to_gfx_bitmap() const
{
auto bitmap = TRY(Gfx::Bitmap::create(Gfx::BitmapFormat::BGRx8888, { m_width, m_height }));
@ -520,6 +539,9 @@ struct SegmentData {
// Set on dictionary segments after they've been decoded.
Optional<Vector<NonnullRefPtr<Symbol>>> symbols;
// Set on pattern segments after they've been decoded.
Optional<Vector<NonnullRefPtr<Symbol>>> patterns;
};
// 7.4.8.5 Page segment flags
@ -777,7 +799,7 @@ static ErrorOr<void> decode_segment_headers(JBIG2LoadingContext& context, Readon
if (segment_headers.size() != segment_datas.size())
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Segment headers and segment datas have different sizes");
for (size_t i = 0; i < segment_headers.size(); ++i) {
context.segments.append({ segment_headers[i], segment_datas[i], {} });
context.segments.append({ segment_headers[i], segment_datas[i], {}, {} });
context.segments_by_number.set(segment_headers[i].segment_number, context.segments.size() - 1);
}
@ -1776,9 +1798,44 @@ struct PatternDictionaryDecodingInputParameters {
};
// 6.7 Pattern Dictionary Decoding Procedure
static ErrorOr<void> pattern_dictionary_decoding_procedure(PatternDictionaryDecodingInputParameters const&, ReadonlyBytes)
static ErrorOr<Vector<NonnullRefPtr<Symbol>>> pattern_dictionary_decoding_procedure(PatternDictionaryDecodingInputParameters const& inputs, ReadonlyBytes data, Vector<JBIG2::ArithmeticDecoder::Context>& contexts)
{
return Error::from_string_literal("JBIG2ImageDecoderPlugin: Cannot decode pattern dictionary yet");
// Table 27 – Parameters used to decode a pattern dictionary's collective bitmap
GenericRegionDecodingInputParameters generic_inputs;
generic_inputs.is_modified_modified_read = inputs.uses_mmr;
generic_inputs.region_width = (inputs.gray_max + 1) * inputs.width;
generic_inputs.region_height = inputs.height;
generic_inputs.gb_template = inputs.hd_template;
generic_inputs.is_typical_prediction_used = false;
generic_inputs.is_extended_reference_template_used = false; // Missing from spec in table 27.
generic_inputs.skip_pattern = OptionalNone {};
generic_inputs.adaptive_template_pixels[0].x = -inputs.width;
generic_inputs.adaptive_template_pixels[0].y = 0;
generic_inputs.adaptive_template_pixels[1].x = -3;
generic_inputs.adaptive_template_pixels[1].y = -1;
generic_inputs.adaptive_template_pixels[2].x = 2;
generic_inputs.adaptive_template_pixels[2].y = -2;
generic_inputs.adaptive_template_pixels[3].x = -2;
generic_inputs.adaptive_template_pixels[3].y = -2;
Optional<JBIG2::ArithmeticDecoder> decoder;
if (!inputs.uses_mmr) {
decoder = TRY(JBIG2::ArithmeticDecoder::initialize(data));
generic_inputs.arithmetic_decoder = &decoder.value();
}
auto bitmap = TRY(generic_region_decoding_procedure(generic_inputs, data, contexts));
Vector<NonnullRefPtr<Symbol>> patterns;
for (u32 gray = 0; gray <= inputs.gray_max; ++gray) {
int x = gray * inputs.width;
auto pattern = TRY(bitmap->subbitmap({ x, 0, static_cast<int>(inputs.width), static_cast<int>(inputs.height) }));
patterns.append(Symbol::create(move(pattern)));
}
dbgln_if(JBIG2_DEBUG, "Pattern dictionary: {} patterns", patterns.size());
return patterns;
}
static ErrorOr<void> decode_symbol_dictionary(JBIG2LoadingContext& context, SegmentData& segment)
@ -2041,7 +2098,7 @@ static ErrorOr<void> decode_immediate_text_region(JBIG2LoadingContext& context,
return {};
}
static ErrorOr<void> decode_pattern_dictionary(JBIG2LoadingContext&, SegmentData const& segment)
static ErrorOr<void> decode_pattern_dictionary(JBIG2LoadingContext&, SegmentData& segment)
{
// 7.4.4 Pattern dictionary segment syntax
FixedMemoryStream stream(segment.data);
@ -2070,12 +2127,15 @@ static ErrorOr<void> decode_pattern_dictionary(JBIG2LoadingContext&, SegmentData
// 7.4.4.2 Decoding a pattern dictionary segment
dbgln_if(JBIG2_DEBUG, "Pattern dictionary: uses_mmr={}, hd_template={}, width={}, height={}, gray_max={}", uses_mmr, hd_template, width, height, gray_max);
auto data = segment.data.slice(TRY(stream.tell()));
// "1) Interpret its header, as described in 7.4.4.1."
// Done!
// "2) As described in E.3.7, reset all the arithmetic coding statistics to zero."
// FIXME
Vector<JBIG2::ArithmeticDecoder::Context> contexts;
if (!uses_mmr)
contexts.resize(1 << number_of_context_bits_for_template(hd_template));
// "3) Invoke the pattern dictionary decoding procedure described in 6.7, with the parameters to the pattern
// dictionary decoding procedure set as shown in Table 35."
@ -2085,7 +2145,10 @@ static ErrorOr<void> decode_pattern_dictionary(JBIG2LoadingContext&, SegmentData
inputs.height = height;
inputs.gray_max = gray_max;
inputs.hd_template = hd_template;
TRY(pattern_dictionary_decoding_procedure(inputs, segment.data.slice(TRY(stream.tell()))));
auto result = TRY(pattern_dictionary_decoding_procedure(inputs, data, contexts));
segment.patterns = move(result);
return {};
}