LibGfx/TIFF: Read the ExtraSamples tag

Userland/Libraries/LibGfx/TIFFGenerator.py

@@ -90,6 +90,12 @@ class SampleFormat(EnumWithExportName):
     Undefined = 4
 
 
+class ExtraSample(EnumWithExportName):
+    Unspecified = 0
+    AssociatedAlpha = 1
+    UnassociatedAlpha = 2
+
+
 tag_fields = ['id', 'types', 'counts', 'default', 'name', 'associated_enum']
 
 Tag = namedtuple(
@@ -117,6 +123,7 @@ known_tags: List[Tag] = [
     Tag('296', [TIFFType.UnsignedShort], [], ResolutionUnit.Inch, "ResolutionUnit", ResolutionUnit),
     Tag('339', [TIFFType.UnsignedShort], [], SampleFormat.Unsigned, "SampleFormat", SampleFormat),
     Tag('317', [TIFFType.UnsignedShort], [1], Predictor.NoPrediction, "Predictor", Predictor),
+    Tag('338', [TIFFType.UnsignedShort], [], None, "ExtraSamples", ExtraSample),
     Tag('34675', [TIFFType.Undefined], [], None, "ICCProfile"),
 ]