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LibGfx/TIFF: Make loop_over_pixels autonomous for reading samples

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Let's make the "read a sample" part independent of the decoder. That
will soon allow us to read samples based on the image's parameter
without duplicating the code for every decoder.
This commit is contained in:
Lucas CHOLLET 2023-12-01 00:03:52 -05:00 • committed by Sam Atkins
parent 8b50b689f9
commit ff73d5464a
1 changed files with 22 additions and 34 deletions
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56
Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
View file

@ -76,16 +76,18 @@ private:
BigEndian,
};
template<typename ByteReader>
ErrorOr<void> loop_over_pixels(ByteReader&& byte_reader, Function<ErrorOr<void>(u32)> initializer = {})
template<CallableAs<ErrorOr<ReadonlyBytes>, u32> StripDecoder>
ErrorOr<void> loop_over_pixels(StripDecoder&& strip_decoder)
{
auto const strips_offset = *m_metadata.strip_offsets();
auto const strip_byte_counts = *m_metadata.strip_byte_counts();
for (u32 strip_index = 0; strip_index < strips_offset.size(); ++strip_index) {
TRY(m_stream->seek(strips_offset[strip_index]));
if (initializer)
TRY(initializer(strip_byte_counts[strip_index]));
auto const decoded_bytes = TRY(strip_decoder(strip_byte_counts[strip_index]));
auto decoded_strip = make<FixedMemoryStream>(decoded_bytes);
for (u32 row = 0; row < *m_metadata.rows_per_strip(); row++) {
auto const scanline = row + *m_metadata.rows_per_strip() * strip_index;
if (scanline >= *m_metadata.image_height())
@ -94,7 +96,7 @@ private:
Optional<Color> last_color {};
for (u32 column = 0; column < *m_metadata.image_width(); ++column) {
auto color = Color { TRY(byte_reader()), TRY(byte_reader()), TRY(byte_reader()) };
auto color = Color { TRY(decoded_strip->template read_value<u8>()), TRY(decoded_strip->template read_value<u8>()), TRY(decoded_strip->template read_value<u8>()) };
if (m_metadata.predictor() == Predictor::HorizontalDifferencing && last_color.has_value()) {
color.set_red(last_color->red() + color.red());
@ -116,15 +118,18 @@ private:
m_bitmap = TRY(Bitmap::create(BitmapFormat::BGRA8888, size()));
switch (*m_metadata.compression()) {
case Compression::NoCompression:
TRY(loop_over_pixels([this]() { return read_value<u8>(); }));
case Compression::NoCompression: {
auto identity = [&](u32 num_bytes) {
return m_stream->read_in_place<u8 const>(num_bytes);
};
TRY(loop_over_pixels(move(identity)));
break;
}
case Compression::LZW: {
ByteBuffer decoded_bytes {};
u32 read_head {};
auto initializer = [&](u32 bytes) -> ErrorOr<void> {
auto const encoded_bytes = TRY(m_stream->read_in_place<u8 const>(bytes));
auto decode_lzw_strip = [&](u32 num_bytes) -> ErrorOr<ReadonlyBytes> {
auto const encoded_bytes = TRY(m_stream->read_in_place<u8 const>(num_bytes));
if (encoded_bytes.is_empty())
return Error::from_string_literal("TIFFImageDecoderPlugin: Unable to read from empty LZW strip");
@ -141,31 +146,20 @@ private:
else
decoded_bytes = TRY(Compress::LZWDecoder<BigEndianInputBitStream>::decode_all(encoded_bytes, 8, -1));
read_head = 0;
return {};
return decoded_bytes;
};
auto read_lzw_byte = [&]() -> ErrorOr<u8> {
if (read_head < decoded_bytes.size())
return decoded_bytes[read_head++];
return Error::from_string_literal("TIFFImageDecoderPlugin: Reached end of LZW stream");
};
TRY(loop_over_pixels([read_lzw_byte = move(read_lzw_byte)]() { return read_lzw_byte(); }, move(initializer)));
TRY(loop_over_pixels(move(decode_lzw_strip)));
break;
}
case Compression::PackBits: {
// Section 9: PackBits Compression
OwnPtr<FixedMemoryStream> strip_stream;
ByteBuffer decoded_bytes {};
u32 read_head {};
auto initializer = [&](u32 num_bytes) -> ErrorOr<void> {
strip_stream = make<FixedMemoryStream>(TRY(m_stream->read_in_place<u8 const>(num_bytes)));
auto decode_packbits_strip = [&](u32 num_bytes) -> ErrorOr<ReadonlyBytes> {
auto strip_stream = make<FixedMemoryStream>(TRY(m_stream->read_in_place<u8 const>(num_bytes)));
decoded_bytes.clear();
read_head = 0;
Optional<i8> n {};
Optional<u8> saved_byte {};
@ -201,16 +195,10 @@ private:
}
}
return {};
return decoded_bytes;
};
auto read_packed_byte = [&]() -> ErrorOr<u8> {
if (read_head < decoded_bytes.size())
return decoded_bytes[read_head++];
return Error::from_string_literal("TIFFImageDecoderPlugin: Reached end of PackedBits stream");
};
TRY(loop_over_pixels(move(read_packed_byte), move(initializer)));
TRY(loop_over_pixels(move(decode_packbits_strip)));
break;
}
default: