Baby steps towards an odeon-like animation system. First victim: Drawer.

sky/sdk/lib/widgets/animated_component.dart

Index: sky/sdk/lib/widgets/animated_component.dart
diff --git a/sky/sdk/lib/widgets/animated_component.dart b/sky/sdk/lib/widgets/animated_component.dart
index 025e3a4fb3f2d06c06648a306ab24a115692144b..5b1451a8873e0f2a3df08185ba2497a8168c074b 100644
--- a/sky/sdk/lib/widgets/animated_component.dart
+++ b/sky/sdk/lib/widgets/animated_component.dart
@@ -4,7 +4,11 @@
 
 import 'dart:async';
 
+import 'package:vector_math/vector_math.dart';
+
 import '../animation/animated_value.dart';
+import '../animation/animation_performance.dart';
+import '../animation/curves.dart';
 import 'basic.dart';
 
 class _AnimationEntry {
@@ -50,3 +54,22 @@ abstract class AnimatedComponent extends Component {
   }
 
 }
+
+// Types of things that can be animated in a component. Use build() to
+// construct the final Widget based on the animation state.
+// TODO(mpcomplete): the idea here is to eventually have an AnimatedCollection
+// which assembles a container based on a list of animated things. e.g. if you
+// want to animate position, opacity, and shadow, you add those animators to an
+// AnimatedCollection and just call collection.build() to construct your
+// widget.
+
+class AnimatedPosition extends AnimatedType<Point> {
+  AnimatedPosition(Point begin, Point end, {Curve curve: linear})
+      : super(begin, end, curve: curve);
+
+  Widget build(Widget child) {
+    Matrix4 transform = new Matrix4.identity();
+    transform.translate(value.x, value.y);
+    return new Transform(transform: transform, child: child);
+  }
+}