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LibGfx/CCITT: Extract the code to decode a single CCITT3 1D line

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This will be handy for the pure CCITT Group 3 decoder too :^)
This commit is contained in:
Lucas CHOLLET 2024-01-14 19:15:01 -05:00 • committed by Andreas Kling
parent 6a94b09029
commit 1cc10a6245
1 changed files with 27 additions and 20 deletions
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47
Userland/Libraries/LibGfx/ImageFormats/CCITTDecoder.cpp
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@ -264,35 +264,21 @@ Optional<Code> get_terminal_code(Color color, u16 code_word, u8 code_size)
return get_code_from_table(black_terminating_codes, code_word, code_size); return get_code_from_table(black_terminating_codes, code_word, code_size);
} }
} ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_stream, BigEndianOutputBitStream& decoded_bits, u32 image_width)
ErrorOr<ByteBuffer> decode_ccitt_rle(ReadonlyBytes bytes, u32 image_width, u32 image_height)
{ {
auto strip_stream = make<FixedMemoryStream>(bytes);
auto bit_stream = make<BigEndianInputBitStream>(MaybeOwned<Stream>(*strip_stream));
ByteBuffer decoded_bytes = TRY(ByteBuffer::create_zeroed(ceil_div(image_width * image_height, 8)));
auto output_stream = make<FixedMemoryStream>(decoded_bytes.bytes());
auto decoded_bits = make<BigEndianOutputBitStream>(MaybeOwned<Stream>(*output_stream));
auto const ccitt_white = Color::NamedColor::White; auto const ccitt_white = Color::NamedColor::White;
auto const ccitt_black = Color::NamedColor::Black; auto const ccitt_black = Color::NamedColor::Black;
Color current_color { ccitt_black }; Color current_color { ccitt_white };
u32 run_length {}; u32 run_length = 0;
u32 column = 0; u32 column = 0;
while (!bit_stream->is_eof() || run_length > 0) { while (column < image_width) {
if (run_length > 0) { if (run_length > 0) {
run_length--; run_length--;
TRY(decoded_bits->write_bits(current_color == ccitt_white ? 0u : 1u, 1)); TRY(decoded_bits.write_bits(current_color == ccitt_white ? 0u : 1u, 1));
++column; ++column;
if (column == image_width) {
column = 0;
bit_stream->align_to_byte_boundary();
TRY(decoded_bits->align_to_byte_boundary());
}
continue; continue;
} }
@ -306,7 +292,7 @@ ErrorOr<ByteBuffer> decode_ccitt_rle(ReadonlyBytes bytes, u32 image_width, u32 i
u16 potential_code {}; u16 potential_code {};
while (size < 14) { while (size < 14) {
potential_code <<= 1; potential_code <<= 1;
potential_code |= TRY(bit_stream->read_bit()); potential_code |= TRY(input_bit_stream.read_bit());
size++; size++;
if (auto const maybe_markup = get_markup_code(current_color, potential_code, size); maybe_markup.has_value()) { if (auto const maybe_markup = get_markup_code(current_color, potential_code, size); maybe_markup.has_value()) {
@ -327,6 +313,27 @@ ErrorOr<ByteBuffer> decode_ccitt_rle(ReadonlyBytes bytes, u32 image_width, u32 i
return Error::from_string_literal("TIFFImageDecoderPlugin: CCITT codes encode for more that a line"); return Error::from_string_literal("TIFFImageDecoderPlugin: CCITT codes encode for more that a line");
} }
return {};
}
}
ErrorOr<ByteBuffer> decode_ccitt_rle(ReadonlyBytes bytes, u32 image_width, u32 image_height)
{
auto strip_stream = make<FixedMemoryStream>(bytes);
auto bit_stream = make<BigEndianInputBitStream>(MaybeOwned<Stream>(*strip_stream));
ByteBuffer decoded_bytes = TRY(ByteBuffer::create_zeroed(ceil_div(image_width * image_height, 8)));
auto output_stream = make<FixedMemoryStream>(decoded_bytes.bytes());
auto decoded_bits = make<BigEndianOutputBitStream>(MaybeOwned<Stream>(*output_stream));
while (!bit_stream->is_eof()) {
TRY(decode_single_ccitt3_1d_line(*bit_stream, *decoded_bits, image_width));
bit_stream->align_to_byte_boundary();
TRY(decoded_bits->align_to_byte_boundary());
}
return decoded_bytes; return decoded_bytes;
} }