LibGfx/TIFF: Manually check for the presence of two baseline tags

Namely: BitsPerSample and SamplesPerPixel.

Userland/Libraries/LibGfx/ImageFormats/TIFFLoader.cpp

@@ -103,6 +103,12 @@ public:
         if (!m_metadata.rows_per_strip().has_value() && segment_byte_counts()->size() != 1 && !is_tiled())
             return Error::from_string_literal("TIFFImageDecoderPlugin: RowsPerStrip is not provided and impossible to deduce");
 
+        if (!m_metadata.bits_per_sample().has_value())
+            return Error::from_string_literal("TIFFImageDecoderPlugin: Tag BitsPerSample is missing");
+
+        if (!m_metadata.samples_per_pixel().has_value())
+            return Error::from_string_literal("TIFFImageDecoderPlugin: Tag SamplesPerPixel is missing");
+
         if (any_of(*m_metadata.bits_per_sample(), [](auto bit_depth) { return bit_depth == 0 || bit_depth > 32; }))
             return Error::from_string_literal("TIFFImageDecoderPlugin: Invalid value in BitsPerSample");
 

Userland/Libraries/LibGfx/TIFFGenerator.py

@@ -125,7 +125,7 @@ Tag = namedtuple(
 known_tags: List[Tag] = [
     Tag('256', [TIFFType.UnsignedShort, TIFFType.UnsignedLong], [1], None, "ImageWidth", is_required=True),
     Tag('257', [TIFFType.UnsignedShort, TIFFType.UnsignedLong], [1], None, "ImageLength", is_required=True),
-    Tag('258', [TIFFType.UnsignedShort], [], None, "BitsPerSample", is_required=True),
+    Tag('258', [TIFFType.UnsignedShort], [], None, "BitsPerSample", is_required=False),
     Tag('259', [TIFFType.UnsignedShort], [1], None, "Compression", Compression, is_required=True),
     Tag('262', [TIFFType.UnsignedShort], [1], None, "PhotometricInterpretation",
         PhotometricInterpretation, is_required=True),
@@ -134,7 +134,7 @@ known_tags: List[Tag] = [
     Tag('272', [TIFFType.ASCII], [], None, "Model"),
     Tag('273', [TIFFType.UnsignedShort, TIFFType.UnsignedLong], [], None, "StripOffsets", is_required=False),
     Tag('274', [TIFFType.UnsignedShort], [1], Orientation.Default, "Orientation", Orientation),
-    Tag('277', [TIFFType.UnsignedShort], [1], None, "SamplesPerPixel", is_required=True),
+    Tag('277', [TIFFType.UnsignedShort], [1], None, "SamplesPerPixel", is_required=False),
     Tag('278', [TIFFType.UnsignedShort, TIFFType.UnsignedLong], [1], None, "RowsPerStrip", is_required=False),
     Tag('279', [TIFFType.UnsignedShort, TIFFType.UnsignedLong], [], None, "StripByteCounts", is_required=False),
     Tag('282', [TIFFType.UnsignedRational], [1], None, "XResolution"),