[Effen] Add AnimatedComponent base class

sky/framework/components/animated_component.dart

Index: sky/framework/components/animated_component.dart
diff --git a/sky/framework/components/animated_component.dart b/sky/framework/components/animated_component.dart
new file mode 100644
index 0000000000000000000000000000000000000000..698b66e626a7cc1dcd4f7361a40ad7c7cf94a663
--- /dev/null
+++ b/sky/framework/components/animated_component.dart
@@ -0,0 +1,34 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import '../animation/animated_value.dart';
+import '../fn.dart';
+import 'dart:mirrors';
+
+class AnimatedComponent extends Component {
+  AnimatedComponent({ Object key }) : super(key: key, stateful: true);
+
+  animateField(AnimatedValue value, Symbol symbol) {
+    // TODO(rafaelw): Assert symbol is present on |this|, is private and
+    // is over the same parameterized type as the animated value.
+    var mirror = reflect(this);
+    var subscription;
+
+    mirror.setField(symbol, value.value);
+
+    onDidMount(() {
+      subscription = value.onValueChanged.listen((_) {
+        mirror.setField(symbol, value.value);
+        scheduleBuild();
+      });
+    });
+
+    onDidUnmount(() {
+      if (subscription != null) {
+        subscription.cancel();
+        subscription = null;
+      }
+    });
+  }
+}