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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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54
Userland/Libraries/LibGfx/ImageFormats/CCITTDecoder.cpp
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@ -272,6 +272,36 @@ Color invert(Color current_color)
return current_color == ccitt_white ? ccitt_black : ccitt_white;
}
ErrorOr<u32> read_run_length(BigEndianInputBitStream& input_bit_stream, Color current_color, u32 image_width, u32 column)
{
u8 size {};
u16 potential_code {};
u32 run_length {};
while (size < 14) {
potential_code <<= 1;
potential_code |= TRY(input_bit_stream.read_bit());
size++;
if (auto const maybe_markup = get_markup_code(current_color, potential_code, size); maybe_markup.has_value()) {
run_length += maybe_markup->run_length;
// OK, let's reset the loop to read a terminal code now
size = 0;
potential_code = 0;
} else if (auto const maybe_terminal = get_terminal_code(current_color, potential_code, size); maybe_terminal.has_value()) {
run_length += maybe_terminal->run_length;
break;
}
}
if (size == 14)
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 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
@ -291,29 +321,7 @@ ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_st
current_color = invert(current_color);
u8 size {};
u16 potential_code {};
while (size < 14) {
potential_code <<= 1;
potential_code |= TRY(input_bit_stream.read_bit());
size++;
if (auto const maybe_markup = get_markup_code(current_color, potential_code, size); maybe_markup.has_value()) {
run_length += maybe_markup->run_length;
// OK, let's reset the loop to read a terminal code now
size = 0;
potential_code = 0;
} else if (auto const maybe_terminal = get_terminal_code(current_color, potential_code, size); maybe_terminal.has_value()) {
run_length += maybe_terminal->run_length;
break;
}
}
if (size == 14)
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");
run_length += TRY(read_run_length(input_bit_stream, current_color, image_width, column));
}
TRY(decoded_bits.align_to_byte_boundary());