fonts: Consider Tertiary Ideographic Plane to be CJK

components/gfx/tests/text_util.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use gfx::text::util::{transform_text, CompressionMode};
+use gfx::text::util::{is_cjk, transform_text, CompressionMode};
 
 #[test]
 fn test_transform_compress_none() {
@@ -104,3 +104,25 @@ fn test_transform_compress_whitespace_newline_no_incoming() {
         assert_eq!(trimmed_str, oracle)
     }
 }
+
+#[test]
+fn test_is_cjk() {
+    let test_strs = [
+        ('〇', true),
+        ('㐀', true),
+        ('あ', true),
+        ('ア', true),
+        ('㆒', true),
+        ('ㆣ', true),
+        ('龥', true),
+        ('𪣻', true),
+        ('a', false),
+        ('🙂', false),
+        ('©', false),
+    ];
+
+    for &(test, oracle) in test_strs.iter() {
+        let symbol: bool = is_cjk(test);
+        assert_eq!(symbol, oracle);
+    }
+}

components/gfx/text/util.rs

@@ -149,5 +149,6 @@ pub fn is_cjk(codepoint: char) -> bool {
     }
 
     // https://en.wikipedia.org/wiki/Plane_(Unicode)#Supplementary_Ideographic_Plane
-    unicode_plane(codepoint) == 2
+    // https://en.wikipedia.org/wiki/Plane_(Unicode)#Tertiary_Ideographic_Plane
+    unicode_plane(codepoint) == 2 || unicode_plane(codepoint) == 3
 }