[CBDT] Implement Format18 get_extens

Part of https://github.com/harfbuzz/harfbuzz/issues/1327

diff --git a/src/hb-ot-color-cbdt-table.hh b/src/hb-ot-color-cbdt-table.hh
index f1b1196..614cc80 100644 (file)
--- a/src/hb-ot-color-cbdt-table.hh
+++ b/src/hb-ot-color-cbdt-table.hh
@@ -437,8 +437,16 @@ struct CBDT
            const GlyphBitmapDataFormat17& glyphFormat17 =
                StructAtOffset<GlyphBitmapDataFormat17> (this->cbdt, image_offset);
            glyphFormat17.glyphMetrics.get_extents (extents);
+           break;
+         }
+         case 18: {
+           if (unlikely (image_length < GlyphBitmapDataFormat18::min_size))
+             return false;
+           const GlyphBitmapDataFormat18& glyphFormat18 =
+               StructAtOffset<GlyphBitmapDataFormat18> (this->cbdt, image_offset);
+           glyphFormat18.glyphMetrics.get_extents (extents);
+           break;
          }
-         break;
          default:
            // TODO: Support other image formats.
            return false;