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LibGfx/TIFF: Put manage_extra_channels in its own function

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Lucas CHOLLET 2024-01-18 19:23:11 -05:00 • committed by Andrew Kaster
parent 3f4bf7a0c7
commit 984272d83e
1 changed files with 22 additions and 20 deletions
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42
Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
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@ -161,44 +161,46 @@ private:
return OptionalNone {};
}
ErrorOr<Color> read_color(BigEndianInputBitStream& stream)
ErrorOr<u8> manage_extra_channels(BigEndianInputBitStream& stream, Vector<u32> const& bits_per_sample) const
{
auto bits_per_sample = *m_metadata.bits_per_sample();
// Section 7: Additional Baseline TIFF Requirements
// Some TIFF files may have more components per pixel than you think. A Baseline TIFF reader must skip over
// them gracefully, using the values of the SamplesPerPixel and BitsPerSample fields.
auto manage_extra_channels = [&]() -> ErrorOr<u8> {
// Both unknown and alpha channels are considered as extra channels, so let's iterate over
// them, conserve the alpha value (if any) and discard everything else.
auto const number_base_channels = samples_for_photometric_interpretation();
auto const alpha_index = alpha_channel_index();
// Both unknown and alpha channels are considered as extra channels, so let's iterate over
// them, conserve the alpha value (if any) and discard everything else.
Optional<u8> alpha {};
auto const number_base_channels = samples_for_photometric_interpretation();
auto const alpha_index = alpha_channel_index();
for (u8 i = number_base_channels; i < bits_per_sample.size(); ++i) {
if (alpha_index == i)
alpha = TRY(read_component(stream, bits_per_sample[i]));
else
TRY(read_component(stream, bits_per_sample[i]));
}
Optional<u8> alpha {};
return alpha.value_or(NumericLimits<u8>::max());
};
for (u8 i = number_base_channels; i < bits_per_sample.size(); ++i) {
if (alpha_index == i)
alpha = TRY(read_component(stream, bits_per_sample[i]));
else
TRY(read_component(stream, bits_per_sample[i]));
}
return alpha.value_or(NumericLimits<u8>::max());
}
ErrorOr<Color> read_color(BigEndianInputBitStream& stream)
{
auto bits_per_sample = *m_metadata.bits_per_sample();
if (m_metadata.photometric_interpretation() == PhotometricInterpretation::RGB) {
auto const first_component = TRY(read_component(stream, bits_per_sample[0]));
auto const second_component = TRY(read_component(stream, bits_per_sample[1]));
auto const third_component = TRY(read_component(stream, bits_per_sample[2]));
auto const alpha = TRY(manage_extra_channels());
auto const alpha = TRY(manage_extra_channels(stream, bits_per_sample));
return Color(first_component, second_component, third_component, alpha);
}
if (m_metadata.photometric_interpretation() == PhotometricInterpretation::RGBPalette) {
auto const index = TRY(stream.read_bits<u16>(bits_per_sample[0]));
auto const alpha = TRY(manage_extra_channels());
auto const alpha = TRY(manage_extra_channels(stream, bits_per_sample));
// SamplesPerPixel == 1 is a requirement for RGBPalette
// From description of PhotometricInterpretation in Section 8: Baseline Field Reference Guide
@ -229,7 +231,7 @@ private:
if (m_metadata.photometric_interpretation() == PhotometricInterpretation::WhiteIsZero)
luminosity = ~luminosity;
auto const alpha = TRY(manage_extra_channels());
auto const alpha = TRY(manage_extra_channels(stream, bits_per_sample));
return Color(luminosity, luminosity, luminosity, alpha);
}