Move AnimatedComponent away from mirrors and towards a callback-based setter.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1171273002

sdk/lib/framework/animation/animated_value.dart

@@ -9,7 +9,7 @@ import 'generators.dart';
 typedef void Callback ();
 
 class AnimatedValue {
-  StreamController _controller = new StreamController.broadcast(sync: true);
+  StreamController<double> _controller = new StreamController<double>.broadcast(sync: true);
   AnimationGenerator _animation;
   Completer _completer;
   double _value;

sdk/lib/framework/components2/animated_component.dart

@@ -4,32 +4,23 @@
 
 import '../animation/animated_value.dart';
 import '../fn2.dart';
-import 'dart:mirrors';
+import 'dart:async';
 
-abstract class AnimatedComponent extends Component {
-  AnimatedComponent({ Object key }) : super(key: key, stateful: true);
-
-  var _debugAnimatedFields = new Set<Symbol>();
-  bool _debugIsNotYetAnimated(Symbol s) {
-    return _debugAnimatedFields.add(s);
-  }
+typedef void SetterFunction(double value);
 
-  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;
+abstract class AnimatedComponent extends Component {
 
-    assert(_debugIsNotYetAnimated(symbol));
-    mirror.setField(symbol, value.value);
+  AnimatedComponent({ Object key }) : super(key: key, stateful: true);
 
+  animate(AnimatedValue value, SetterFunction setter) {
+    setter(value.value);
+    StreamSubscription<double> subscription;
     onDidMount(() {
       subscription = value.onValueChanged.listen((_) {
-        mirror.setField(symbol, value.value);
+        setter(value.value);
         scheduleBuild();
       });
     });
-
     onDidUnmount(() {
       if (subscription != null) {
         subscription.cancel();
@@ -37,4 +28,5 @@ abstract class AnimatedComponent extends Component {
       }
     });
   }
+
 }

sdk/lib/framework/components2/drawer.dart

@@ -104,7 +104,9 @@ class Drawer extends AnimatedComponent {
     this.children,
     this.level: 0
   }) : super(key: key) {
-    animateField(controller.position, #_position);
+    animate(controller.position, (double value) {
+      _position = value;
+    });
   }
 
   UINode build() {

sdk/lib/framework/components2/popup_menu.dart

@@ -61,7 +61,9 @@ class PopupMenu extends AnimatedComponent {
 
   PopupMenu({ Object key, this.controller, this.items, this.level })
       : super(key: key) {
-    animateField(controller.position, #_position);
+    animate(controller.position, (double value) {
+      _position = value;
+    });
     // onDidMount(_measureSize);
   }