Tests: Add tests for jpeg2000 palette handling difference in PDF files

I created indexed-small.jp2 with this script:
https://github.com/nico/hack/blob/d4772bae/make_palettized_jpeg2000.py

I created jpeg2000-indexed-small.pdf with a local script that
creates a PDF file embedding a jpeg2000 file, and then manually changed
the indexed color space in the PDF to use 0x7f bytes for all bytes
in the palette that were 0xff. Since PDF renderers are supposed to
use the palette that's in the PDF file, not the one that's in the
JPEG2000 data, this means that the image shows up darker in the
PDF than when viewing the file standalone. (It'd also be possible
to change the palette colors to something completely different.
I just went with "make it slightly darker" since that seems less
confusing.)

Tests/LibGfx/TestImageDecoder.cpp

@@ -909,6 +909,22 @@ TEST_CASE(test_jpeg2000_decode_indexed)
     }
 }
 
+TEST_CASE(test_jpeg2000_decode_indexed_small_raw)
+{
+    auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("jpeg2000/indexed-small.jp2"sv)));
+    EXPECT(Gfx::JPEG2000ImageDecoderPlugin::sniff(file->bytes()));
+    auto plugin_decoder = TRY_OR_FAIL(Gfx::JPEG2000ImageDecoderPlugin::create(file->bytes()));
+
+    auto frame = TRY_OR_FAIL(plugin_decoder->frame(0)).image;
+    EXPECT_EQ(frame->size(), Gfx::IntSize(3, 2));
+    EXPECT_EQ(frame->scanline(0)[0], Gfx::Color(255, 0, 0).value());
+    EXPECT_EQ(frame->scanline(0)[1], Gfx::Color(0, 255, 0).value());
+    EXPECT_EQ(frame->scanline(0)[2], Gfx::Color(0, 0, 255).value());
+    EXPECT_EQ(frame->scanline(1)[0], Gfx::Color(0, 255, 255).value());
+    EXPECT_EQ(frame->scanline(1)[1], Gfx::Color(255, 0, 255).value());
+    EXPECT_EQ(frame->scanline(1)[2], Gfx::Color(255, 255, 0).value());
+}
+
 TEST_CASE(test_jpeg2000_decode_unsupported)
 {
     Array test_inputs = {

Tests/LibPDF/CMakeLists.txt

@@ -13,6 +13,7 @@ set(TEST_FILES
     encoding.pdf
     encryption_nocopy.pdf
     jbig2-globals.pdf
+    jpeg2000-indexed-small.pdf
     linearized.pdf
     non-linearized.pdf
     offset.pdf

Tests/LibPDF/TestPDF.cpp

@@ -386,3 +386,29 @@ TEST_CASE(render)
     // MyCalGray
     EXPECT_EQ(bitmap->get_pixel(270, 370 - 320), Gfx::Color::NamedColor::Black);
 }
+
+TEST_CASE(render_jpeg2000_indexed)
+{
+#if !defined(AK_OS_SERENITY)
+    // Get from Build/lagom/bin/TestPDF to Build/lagom/Root/res.
+    auto source_root = LexicalPath(MUST(Core::System::current_executable_path())).parent().parent().string();
+    Core::ResourceImplementation::install(make<Core::ResourceImplementationFile>(MUST(String::formatted("{}/Root/res", source_root))));
+#endif
+
+    auto file = MUST(Core::MappedFile::map("jpeg2000-indexed-small.pdf"sv));
+    auto document = MUST(PDF::Document::create(file->bytes()));
+    MUST(document->initialize());
+    EXPECT_EQ(document->get_page_count(), 1U);
+
+    auto page = MUST(document->get_page(0));
+    auto page_size = Gfx::IntSize { 3, 2 };
+    auto bitmap = MUST(Gfx::Bitmap::create(Gfx::BitmapFormat::BGRx8888, page_size));
+    MUST(PDF::Renderer::render(document, page, bitmap, Color::White, PDF::RenderingPreferences {}));
+
+    EXPECT_EQ(bitmap->scanline(0)[0], Gfx::Color(127, 0, 0).value());
+    EXPECT_EQ(bitmap->scanline(0)[1], Gfx::Color(0, 127, 0).value());
+    EXPECT_EQ(bitmap->scanline(0)[2], Gfx::Color(0, 0, 127).value());
+    EXPECT_EQ(bitmap->scanline(1)[0], Gfx::Color(0, 127, 127).value());
+    EXPECT_EQ(bitmap->scanline(1)[1], Gfx::Color(127, 0, 127).value());
+    EXPECT_EQ(bitmap->scanline(1)[2], Gfx::Color(127, 127, 0).value());
+}