From 9ec34802076b73ed65109ee961115a98341d09e8 Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Thu, 15 Feb 2024 19:47:44 -0500
Subject: [PATCH] LibGfx/TIFF: Add support for Group4Fax encoded images

Note that we don't parse the T6 option group yet.

The test case was generated with GIMP.
---
 Tests/LibGfx/TestImageDecoder.cpp                 |  12 ++++++++++++
 Tests/LibGfx/test-inputs/tiff/ccitt4.tiff         | Bin 0 -> 621 bytes
 .../Libraries/LibGfx/ImageFormats/TIFFLoader.cpp  |  14 ++++++++++++++
 3 files changed, 26 insertions(+)
 create mode 100644 Tests/LibGfx/test-inputs/tiff/ccitt4.tiff

diff --git a/Tests/LibGfx/TestImageDecoder.cpp b/Tests/LibGfx/TestImageDecoder.cpp
index 7e8a63048f..48cd495193 100644
--- a/Tests/LibGfx/TestImageDecoder.cpp
+++ b/Tests/LibGfx/TestImageDecoder.cpp
@@ -654,6 +654,18 @@ TEST_CASE(test_tiff_ccitt3_2d_fill)
     EXPECT_EQ(frame.image->get_pixel(60, 75), Gfx::Color::NamedColor::Black);
 }
 
+TEST_CASE(test_tiff_ccitt4)
+{
+    auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("tiff/ccitt4.tiff"sv)));
+    EXPECT(Gfx::TIFFImageDecoderPlugin::sniff(file->bytes()));
+    auto plugin_decoder = TRY_OR_FAIL(Gfx::TIFFImageDecoderPlugin::create(file->bytes()));
+
+    auto frame = TRY_OR_FAIL(expect_single_frame_of_size(*plugin_decoder, { 400, 300 }));
+
+    EXPECT_EQ(frame.image->get_pixel(0, 0), Gfx::Color::NamedColor::White);
+    EXPECT_EQ(frame.image->get_pixel(60, 75), Gfx::Color::NamedColor::Black);
+}
+
 TEST_CASE(test_tiff_lzw)
 {
     auto file = TRY_OR_FAIL(Core::MappedFile::map(TEST_INPUT("tiff/lzw.tiff"sv)));
diff --git a/Tests/LibGfx/test-inputs/tiff/ccitt4.tiff b/Tests/LibGfx/test-inputs/tiff/ccitt4.tiff
new file mode 100644
index 0000000000000000000000000000000000000000..418b5cc244ce31b62a3d5f784c27b3056a149900
GIT binary patch
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diff --git a/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp b/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
index dfcbfa59ba..62384797b5 100644
--- a/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
+++ b/Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp
@@ -436,6 +436,20 @@ private:
             TRY(loop_over_pixels(move(decode_group3_segment)));
             break;
         }
+        case Compression::Group4Fax: {
+            TRY(ensure_tags_are_correct_for_ccitt());
+
+            // FIXME: We need to parse T6 options
+            ByteBuffer decoded_bytes {};
+            auto decode_group3_segment = [&](u32 num_bytes, IntSize segment_size) -> ErrorOr<ReadonlyBytes> {
+                auto const encoded_bytes = TRY(read_bytes_considering_fill_order(num_bytes));
+                decoded_bytes = TRY(CCITT::decode_ccitt_group4(encoded_bytes, segment_size.width(), segment_size.height()));
+                return decoded_bytes;
+            };
+
+            TRY(loop_over_pixels(move(decode_group3_segment)));
+            break;
+        }
         case Compression::LZW: {
             ByteBuffer decoded_bytes {};
             auto decode_lzw_segment = [&](u32 num_bytes, IntSize) -> ErrorOr<ReadonlyBytes> {