Implement the unicode-bidi property

components/gfx/text/util.rs

@@ -92,9 +92,9 @@ pub fn transform_text(text: &str,
         }
     }
 
-    fn is_always_discardable_char(_ch: char) -> bool {
-        // TODO: check for bidi control chars, soft hyphens.
-        false
+    fn is_always_discardable_char(ch: char) -> bool {
+        // TODO: check for soft hyphens.
+        is_bidi_control(ch)
     }
 }
 
@@ -105,3 +105,12 @@ pub fn float_to_fixed(before: usize, f: f64) -> i32 {
 pub fn fixed_to_float(before: usize, f: i32) -> f64 {
     f as f64 * 1.0f64 / ((1i32 << before) as f64)
 }
+
+pub fn is_bidi_control(c: char) -> bool {
+    match c {
+        '\u{202A}'...'\u{202E}' => true,
+        '\u{2066}'...'\u{2069}' => true,
+        '\u{200E}' | '\u{200F}' | '\u{061C}' => true,
+        _ => false
+    }
+}