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LibGfx/JPEG2000: Implement tag trees

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A tag tree is a data structure used for deserializing JPEG2000
packet headers.

We don't use them for anything yet, except from tests.

The implementation feels a bit awkward to me, but we can always polish
it later.

The spec thankfully includes two concrete examples. The code is
correct enough to pass those -- I added them as test.
This commit is contained in:
Nico Weber 2024-04-11 22:50:29 -04:00 • committed by Tim Schumacher
parent 99b2eff988
commit 7296b0fa43
Notes: sideshowbarker 2024-07-17 01:04:03 +09:00
3 changed files with 171 additions and 0 deletions
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53
Tests/LibGfx/TestImageDecoder.cpp
View file

@ -606,6 +606,59 @@ TEST_CASE(test_jpeg2000_gray)
EXPECT_EQ(icc_bytes->size(), 912u);
}
TEST_CASE(test_jpeg2000_tag_tree)
{
{
// The example from the NOTE at the end of B.10.2 Tag trees:
auto tree = TRY_OR_FAIL(Gfx::JPEG2000::TagTree::create(6, 3));
auto bits = to_array<u8>({
0, 1, 1, 1, 1, // q3(0, 0)
0, 0, 1, // q3(1, 0)
1, 0, 1, // q3(2, 0)
});
size_t index = 0;
Function<ErrorOr<bool>()> read_bit = [&]() -> bool {
return bits[index++];
};
EXPECT_EQ(1u, MUST(tree.read_value(0, 0, read_bit)));
EXPECT_EQ(index, 5u);
EXPECT_EQ(3u, MUST(tree.read_value(1, 0, read_bit)));
EXPECT_EQ(index, 8u);
EXPECT_EQ(2u, MUST(tree.read_value(2, 0, read_bit)));
EXPECT_EQ(index, 11u);
}
{
// The inclusion tag tree bits from Table B.5 – Example packet header bit stream.
auto tree = TRY_OR_FAIL(Gfx::JPEG2000::TagTree::create(3, 2));
auto bits = to_array<u8>({
1, 1, 1, // Code-block 0, 0 included for the first time (partial inclusion tag tree)
1, // Code-block 1, 0 included for the first time (partial inclusion tag tree)
0, // Code-block 2, 0 not yet included (partial tag tree)
0, // Code-block 0, 1 not yet included
0, // Code-block 1, 2 not yet included
// Code-block 2, 1 not yet included (no data needed, already conveyed by partial tag tree for code-block 2, 0)
});
size_t index = 0;
Function<ErrorOr<bool>()> read_bit = [&]() -> bool {
return bits[index++];
};
u32 next_layer = 1;
EXPECT_EQ(0u, MUST(tree.read_value(0, 0, read_bit, next_layer)));
EXPECT_EQ(index, 3u);
EXPECT_EQ(0u, MUST(tree.read_value(1, 0, read_bit, next_layer)));
EXPECT_EQ(index, 4u);
EXPECT_EQ(1u, MUST(tree.read_value(2, 0, read_bit, next_layer)));
EXPECT_EQ(index, 5u);
EXPECT_EQ(1u, MUST(tree.read_value(0, 1, read_bit, next_layer)));
EXPECT_EQ(index, 6u);
EXPECT_EQ(1u, MUST(tree.read_value(1, 1, read_bit, next_layer)));
EXPECT_EQ(index, 7u);
EXPECT_EQ(1u, MUST(tree.read_value(2, 1, read_bit, next_layer)));
EXPECT_EQ(index, 7u); // Didn't change!
}
}
TEST_CASE(test_pam_rgb)
{
auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("pnm/2x1.pam"sv)));