Animate basic shapes

components/style/values/generics/rect.rs

@@ -6,6 +6,7 @@
 
 use cssparser::Parser;
 use parser::{Parse, ParserContext};
+use properties::animated_properties::Animatable;
 use std::fmt;
 use style_traits::{ToCss, ParseError};
 
@@ -51,6 +52,24 @@ impl<T> Rect<T>
     }
 }
 
+impl<L> Animatable for Rect<L>
+where
+    L: Animatable,
+{
+    fn add_weighted(
+        &self,
+        other: &Self,
+        self_portion: f64,
+        other_portion: f64,
+    ) -> Result<Self, ()> {
+        let first = self.0.add_weighted(&other.0, self_portion, other_portion)?;
+        let second = self.1.add_weighted(&other.1, self_portion, other_portion)?;
+        let third = self.2.add_weighted(&other.2, self_portion, other_portion)?;
+        let fourth = self.3.add_weighted(&other.3, self_portion, other_portion)?;
+        Ok(Rect(first, second, third, fourth))
+    }
+}
+
 impl<T> From<T> for Rect<T>
     where T: Clone
 {