Implement color value serialization.

src/color.rs

@@ -20,7 +20,13 @@ pub struct RGBA {
 
 impl fmt::Show for RGBA {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "(r={} g={} b={} a={})", self.red, self.green, self.blue, self.alpha)
+        if self.alpha == 1f32 {
+            write!(f, "rgb({}, {}, {})", (self.red * 255.).round(), (self.green * 255.).round(),
+                   (self.blue * 255.).round())
+        } else {
+            write!(f, "rgba({}, {}, {}, {})", (self.red * 255.).round(), (self.green * 255.).round(),
+                   (self.blue * 255.).round(), self.alpha)
+        }
     }
 }
 
@@ -30,6 +36,14 @@ pub enum Color {
     RGBAColor(RGBA),
 }
 
+impl fmt::Show for Color {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            &CurrentColor => write!(f, "currentColor"),
+            &RGBAColor(c) => write!(f, "{}", c),
+        }
+    }
+}
 
 /// Return `Err(())` on invalid or unsupported value (not a color).
 impl Color {

src/tests.rs

@@ -275,6 +275,27 @@ fn serializer() {
 }
 
 
+#[test]
+fn serialize_current_color() {
+    let c = CurrentColor;
+    assert!(format!("{}", c).as_slice() == "currentColor");
+}
+
+
+#[test]
+fn serialize_rgb_full_alpha() {
+    let c = RGBAColor(RGBA { red: 1.0, green: 0.9, blue: 0.8, alpha: 1.0 });
+    assert!(format!("{}", c).as_slice() == "rgb(255, 230, 204)");
+}
+
+
+#[test]
+fn serialize_rgba() {
+    let c = RGBAColor(RGBA { red: 0.1, green: 0.2, blue: 0.3, alpha: 0.5 });
+    assert!(format!("{}", c).as_slice() == "rgba(26, 51, 77, 0.5)");
+}
+
+
 impl ToJson for Result<Rule, SyntaxError> {
     fn to_json(&self) -> json::Json {
         match *self {