LibGfx/TIFF: Parse the T4Options CCITT field

This field is described in: Section 11: CCITT Bilevel Encodings.

Userland/Libraries/LibGfx/ImageFormats/CCITTDecoder.h

@@ -23,4 +23,26 @@ namespace Gfx::CCITT {
 // Section 10: Modified Huffman Compression
 ErrorOr<ByteBuffer> decode_ccitt_rle(ReadonlyBytes bytes, u32 image_width, u32 image_height);
 
+// While this is named for a CCITT context, this struct holds data like TIFF's T4Options tag
+struct Group3Options {
+    enum class Mode : u8 {
+        OneDimension,
+        TwoDimensions,
+    };
+
+    enum class Compression : u8 {
+        Uncompressed,
+        Compressed,
+    };
+
+    enum class UseFillBits : u8 {
+        No = 0,
+        Yes = 1,
+    };
+
+    Mode dimensions = Mode::OneDimension;
+    Compression compression = Compression::Compressed;
+    UseFillBits use_fill_bits = UseFillBits::No;
+};
+
 }

Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp

@@ -18,6 +18,25 @@
 
 namespace Gfx {
 
+namespace {
+
+CCITT::Group3Options parse_t4_options(u32 bit_field)
+{
+    // Section 11: CCITT Bilevel Encodings
+    CCITT::Group3Options options {};
+
+    if (bit_field & 0b001)
+        options.dimensions = CCITT::Group3Options::Mode::TwoDimensions;
+    if (bit_field & 0b010)
+        options.compression = CCITT::Group3Options::Compression::Uncompressed;
+    if (bit_field & 0b100)
+        options.use_fill_bits = CCITT::Group3Options::UseFillBits::Yes;
+
+    return options;
+}
+
+}
+
 namespace TIFF {
 
 class TIFFLoadingContext {

Userland/Libraries/LibGfx/TIFFGenerator.py

@@ -133,6 +133,7 @@ known_tags: List[Tag] = [
     Tag('283', [TIFFType.UnsignedRational], [1], None, "YResolution"),
     Tag('284', [TIFFType.UnsignedShort], [1], PlanarConfiguration.Chunky, "PlanarConfiguration", PlanarConfiguration),
     Tag('285', [TIFFType.ASCII], [], None, "PageName"),
+    Tag('292', [TIFFType.UnsignedLong], [1], 0, "T4Options"),
     Tag('296', [TIFFType.UnsignedShort], [1], ResolutionUnit.Inch, "ResolutionUnit", ResolutionUnit),
     Tag('305', [TIFFType.ASCII], [], None, "Software"),
     Tag('306', [TIFFType.ASCII], [20], None, "DateTime"),