Implment fmt::show for RGBA

Author: gw3583

color.rs

@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use std::ascii::StrAsciiExt;
+use std::fmt;
 
 use ast::*;
 
@@ -17,6 +18,12 @@ pub struct RGBA {
     pub alpha: f32,
 }
 
+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)
+    }
+}
+
 #[deriving(Clone, PartialEq)]
 pub enum Color {
     CurrentColor,