beenull/ladybird
1
0
Fork 0
mirror of https://github.com/LadybirdBrowser/ladybird.git synced 2024-11-26 01:20:25 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 6

LibGfx/TIFF: Decode all PackedBits beforehand

Browse source 
This change doesn't change much on its own. The idea behind this
refactoring is to separate the sample reading from the decoding step.
The decoder returning data byte per byte was fine as we only support
8 bits images, but this assumption won't hold for a long time. So let's
decode everything beforehand and strictly partition the sample reading
code somewhere else.
This commit is contained in:
Lucas CHOLLET 2023-11-30 23:00:41 -05:00 committed by Andreas Kling
parent 4994609af0
commit 1ede4f249d
Notes: sideshowbarker 2024-07-17 18:46:30 +09:00 
Author: https://github.com/LucasChollet
Commit: https://github.com/SerenityOS/serenity/commit/1ede4f249d
Pull-request: https://github.com/SerenityOS/serenity/pull/22109
Reviewed-by: https://github.com/nico ✅
1 changed files with 28 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

39
Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
View file

@ -156,20 +156,31 @@ private:
} }
case Compression::PackBits: { case Compression::PackBits: {
// Section 9: PackBits Compression // Section 9: PackBits Compression
Optional<i8> n;
Optional<u8> saved_byte;
auto read_packed_byte = [&]() -> ErrorOr<u8> { OwnPtr<FixedMemoryStream> strip_stream;
while (true) { 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)));
decoded_bytes.clear();
read_head = 0;
Optional<i8> n {};
Optional<u8> saved_byte {};
while (strip_stream->remaining() > 0 || saved_byte.has_value()) {
if (!n.has_value()) if (!n.has_value())
n = TRY(read_value<i8>()); n = TRY(strip_stream->read_value<i8>());
if (n.value() >= 0 && !saved_byte.has_value()) { if (n.value() >= 0 && !saved_byte.has_value()) {
n.value() = n.value() - 1; n.value() = n.value() - 1;
if (n.value() == -1) if (n.value() == -1)
n.clear(); n.clear();
return read_value<u8>(); decoded_bytes.append(TRY(strip_stream->read_value<u8>()));
continue;
} }
if (n.value() == -128) { if (n.value() == -128) {
@ -178,22 +189,28 @@ private:
} }
if (!saved_byte.has_value()) if (!saved_byte.has_value())
saved_byte = TRY(read_value<u8>()); saved_byte = TRY(strip_stream->read_value<u8>());
n.value() = n.value() + 1; n.value() = n.value() + 1;
auto const byte_backup = *saved_byte; decoded_bytes.append(*saved_byte);
if (n == 1) { if (n == 1) {
saved_byte.clear(); saved_byte.clear();
n.clear(); n.clear();
} }
return byte_backup;
} }
return {};
}; };
TRY(loop_over_pixels(move(read_packed_byte))); 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)));
break; break;
} }
default: default: