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LibGfx/CCITT: Put the code to read the run length in its own function
This is already nice to do for the sole purpose of the readability but that will also become handy for the 2D decoder.
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3d63dd5c53
commit
9116cc3f45
1 changed files with 31 additions and 23 deletions
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@ -272,6 +272,36 @@ Color invert(Color current_color)
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return current_color == ccitt_white ? ccitt_black : ccitt_white;
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}
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ErrorOr<u32> read_run_length(BigEndianInputBitStream& input_bit_stream, Color current_color, u32 image_width, u32 column)
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{
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u8 size {};
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u16 potential_code {};
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u32 run_length {};
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while (size < 14) {
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potential_code <<= 1;
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potential_code |= TRY(input_bit_stream.read_bit());
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size++;
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if (auto const maybe_markup = get_markup_code(current_color, potential_code, size); maybe_markup.has_value()) {
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run_length += maybe_markup->run_length;
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// OK, let's reset the loop to read a terminal code now
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size = 0;
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potential_code = 0;
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} else if (auto const maybe_terminal = get_terminal_code(current_color, potential_code, size); maybe_terminal.has_value()) {
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run_length += maybe_terminal->run_length;
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break;
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}
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}
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if (size == 14)
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return Error::from_string_literal("TIFFImageDecoderPlugin: Invalid CCITT code");
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if (column + run_length > image_width)
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return Error::from_string_literal("TIFFImageDecoderPlugin: CCITT codes encode for more than a line");
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return run_length;
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}
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ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_stream, BigEndianOutputBitStream& decoded_bits, u32 image_width)
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{
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// We always flip the color when entering the loop, so let's initialize the
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@ -291,29 +321,7 @@ ErrorOr<void> decode_single_ccitt3_1d_line(BigEndianInputBitStream& input_bit_st
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current_color = invert(current_color);
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u8 size {};
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u16 potential_code {};
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while (size < 14) {
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potential_code <<= 1;
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potential_code |= TRY(input_bit_stream.read_bit());
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size++;
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if (auto const maybe_markup = get_markup_code(current_color, potential_code, size); maybe_markup.has_value()) {
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run_length += maybe_markup->run_length;
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// OK, let's reset the loop to read a terminal code now
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size = 0;
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potential_code = 0;
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} else if (auto const maybe_terminal = get_terminal_code(current_color, potential_code, size); maybe_terminal.has_value()) {
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run_length += maybe_terminal->run_length;
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break;
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}
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}
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if (size == 14)
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return Error::from_string_literal("TIFFImageDecoderPlugin: Invalid CCITT code");
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if (column + run_length > image_width)
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return Error::from_string_literal("TIFFImageDecoderPlugin: CCITT codes encode for more that a line");
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run_length += TRY(read_run_length(input_bit_stream, current_color, image_width, column));
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}
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TRY(decoded_bits.align_to_byte_boundary());
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