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LibGfx/CCITT: Put the code to read the run length in its own function

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This is already nice to do for the sole purpose of the readability but
that will also become handy for the 2D decoder.
This commit is contained in:
Lucas CHOLLET 2024-02-15 15:51:58 -05:00 • committed by Jelle Raaijmakers
parent 3d63dd5c53
commit 9116cc3f45
1 changed files with 31 additions and 23 deletions
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46
Userland/Libraries/LibGfx/ImageFormats/CCITTDecoder.cpp
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@ -272,27 +272,11 @@ Color invert(Color current_color)
return current_color == ccitt_white ? ccitt_black : ccitt_white;
}
ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_stream, BigEndianOutputBitStream& decoded_bits, u32 image_width)
ErrorOr<u32> read_run_length(BigEndianInputBitStream& input_bit_stream, Color current_color, u32 image_width, u32 column)
{
// We always flip the color when entering the loop, so let's initialize the
// color with black to make the first marker actually be white.
Color current_color { ccitt_black };
u32 run_length = 0;
u32 column = 0;
while (column < image_width) {
if (run_length > 0) {
run_length--;
TRY(decoded_bits.write_bits(current_color == ccitt_white ? 0u : 1u, 1));
++column;
continue;
}
current_color = invert(current_color);
u8 size {};
u16 potential_code {};
u32 run_length {};
while (size < 14) {
potential_code <<= 1;
potential_code |= TRY(input_bit_stream.read_bit());
@ -313,7 +297,31 @@ ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_st
return Error::from_string_literal("TIFFImageDecoderPlugin: Invalid CCITT code");
if (column + run_length > image_width)
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 than a line");
return run_length;
}
ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_stream, BigEndianOutputBitStream& decoded_bits, u32 image_width)
{
// We always flip the color when entering the loop, so let's initialize the
// color with black to make the first marker actually be white.
Color current_color { ccitt_black };
u32 run_length = 0;
u32 column = 0;
while (column < image_width) {
if (run_length > 0) {
run_length--;
TRY(decoded_bits.write_bits(current_color == ccitt_white ? 0u : 1u, 1));
++column;
continue;
}
current_color = invert(current_color);
run_length += TRY(read_run_length(input_bit_stream, current_color, image_width, column));
}
TRY(decoded_bits.align_to_byte_boundary());