Merge remote-tracking branch 'upstream/master'

examples/address_book/lib/main.dart

@@ -11,7 +11,7 @@ class Field extends StatelessComponent {
     this.inputKey,
     this.icon,
     this.placeholder
-  }): super(key: key);
+  }) : super(key: key);
 
   final GlobalKey inputKey;
   final String icon;
@@ -101,7 +101,7 @@ void main() {
     title: 'Address Book',
     theme: theme,
     routes: <String, RouteBuilder>{
-      '/': (NavigatorState navigator, Route route) => new AddressBookHome(navigator: navigator)
+      '/': (RouteArguments args) => new AddressBookHome(navigator: args.navigator)
     }
   ));
 }

examples/demo_launcher/lib/main.dart

@@ -42,8 +42,8 @@ void launch(String relativeUrl, String bundle) {
   activity.startActivity(intent);
 }
 
-class SkyDemo {
-  SkyDemo({
+class FlutterDemo {
+  FlutterDemo({
     name,
     this.href,
     this.bundle,
@@ -60,8 +60,8 @@ class SkyDemo {
   final BoxDecoration decoration;
 }
 
-List<SkyDemo> demos = [
-  new SkyDemo(
+List<FlutterDemo> demos = [
+  new FlutterDemo(
     name: 'Stocks',
     href: '../../stocks/lib/main.dart',
     bundle: 'stocks.skyx',
@@ -74,7 +74,7 @@ List<SkyDemo> demos = [
       )
     )
   ),
-  new SkyDemo(
+  new FlutterDemo(
     name: 'Asteroids',
     href: '../../game/lib/main.dart',
     bundle: 'game.skyx',
@@ -87,7 +87,7 @@ List<SkyDemo> demos = [
       )
     )
   ),
-  new SkyDemo(
+  new FlutterDemo(
     name: 'Fitness',
     href: '../../fitness/lib/main.dart',
     bundle: 'fitness.skyx',
@@ -97,7 +97,7 @@ List<SkyDemo> demos = [
       backgroundColor: Colors.indigo[500]
     )
   ),
-  new SkyDemo(
+  new FlutterDemo(
     name: 'Swipe Away',
     href: '../../widgets/card_collection.dart',
     bundle: 'cards.skyx',
@@ -107,7 +107,7 @@ List<SkyDemo> demos = [
       backgroundColor: Colors.redAccent[200]
     )
   ),
-  new SkyDemo(
+  new FlutterDemo(
     name: 'Interactive Text',
     href: '../../rendering/interactive_flex.dart',
     bundle: 'interactive_flex.skyx',
@@ -120,7 +120,7 @@ List<SkyDemo> demos = [
   // new SkyDemo(
 
   //   'Touch Demo', '../../rendering/touch_demo.dart', 'Simple example showing handling of touch events at a low level'),
-  new SkyDemo(
+  new FlutterDemo(
     name: 'Minedigger Game',
     href: '../../mine_digger/lib/main.dart',
     bundle: 'mine_digger.skyx',
@@ -138,11 +138,19 @@ List<SkyDemo> demos = [
 const double kCardHeight = 120.0;
 const EdgeDims kListPadding = const EdgeDims.all(4.0);
 
-class DemoList extends StatelessComponent {
-  Widget buildCardContents(SkyDemo demo) {
+class DemoCard extends StatelessComponent {
+  DemoCard({ Key key, this.demo }) : super(key: key);
+
+  final FlutterDemo demo;
+
+  Widget build(BuildContext context) {
     return new Container(
+      height: kCardHeight,
+      child: new Card(
+        child: new Container(
           decoration: demo.decoration,
           child: new InkWell(
+            onTap: () => launch(demo.href, demo.bundle),
             child: new Container(
               margin: const EdgeDims.only(top: 24.0, left: 24.0),
               child: new Column([
@@ -155,27 +163,22 @@ class DemoList extends StatelessComponent {
               )
             )
           )
-    );
-  }
-
-  Widget buildDemo(BuildContext context, SkyDemo demo) {
-    return new GestureDetector(
-      key: demo.key,
-      onTap: () => launch(demo.href, demo.bundle),
-      child: new Container(
-        height: kCardHeight,
-        child: new Card(
-          child: buildCardContents(demo)
         )
       )
     );
   }
+}
+
+class DemoList extends StatelessComponent {
+  Widget _buildDemoCard(BuildContext context, FlutterDemo demo) {
+    return new DemoCard(key: demo.key, demo: demo);
+  }
 
   Widget build(BuildContext context) {
-    return new ScrollableList<SkyDemo>(
+    return new ScrollableList<FlutterDemo>(
       items: demos,
       itemExtent: kCardHeight,
-      itemBuilder: buildDemo,
+      itemBuilder: _buildDemoCard,
       padding: kListPadding
     );
   }
@@ -200,10 +203,10 @@ class DemoHome extends StatelessComponent {
 
 void main() {
   runApp(new App(
-    title: 'Sky Demos',
+    title: 'Flutter Demos',
     theme: _theme,
     routes: {
-      '/': (NavigatorState navigator, Route route) => new DemoHome()
+      '/': (RouteArguments args) => new DemoHome()
     }
   ));
 }

examples/fitness/lib/feed.dart

@@ -33,17 +33,15 @@ class DialogMenuItem extends StatelessComponent {
   Function onPressed;
 
   Widget build(BuildContext context) {
-    return new GestureDetector(
-      onTap: onPressed,
-      child: new Container(
+    return new Container(
       height: 48.0,
       child: new InkWell(
+        onTap: onPressed,
         child: new Padding(
           padding: const EdgeDims.symmetric(horizontal: 16.0),
           child: new Row(children)
         )
       )
-      )
     );
   }
 }
@@ -62,25 +60,20 @@ class FeedFragment extends StatefulComponent {
 class FeedFragmentState extends State<FeedFragment> {
   FitnessMode _fitnessMode = FitnessMode.feed;
 
-  AnimationStatus _snackBarStatus = AnimationStatus.dismissed;
+  PerformanceStatus _snackBarStatus = PerformanceStatus.dismissed;
   bool _isShowingSnackBar = false;
 
   void _handleFitnessModeChange(FitnessMode value) {
     setState(() {
       _fitnessMode = value;
-      _drawerShowing = false;
     });
+    config.navigator.pop();
   }
 
-  Drawer buildDrawer() {
-    if (_drawerStatus == AnimationStatus.dismissed)
-      return null;
-    return new Drawer(
-      showing: _drawerShowing,
-      level: 3,
-      onDismissed: _handleDrawerDismissed,
+  void _showDrawer() {
+    showDrawer(
       navigator: config.navigator,
-      children: [
+      child: new Block([
         new DrawerHeader(child: new Text('Fitness')),
         new DrawerItem(
           icon: 'action/view_list',
@@ -100,26 +93,10 @@ class FeedFragmentState extends State<FeedFragment> {
         new DrawerItem(
           icon: 'action/help',
           child: new Text('Help & Feedback'))
-      ]
+      ])
     );
   }
 
-  bool _drawerShowing = false;
-  AnimationStatus _drawerStatus = AnimationStatus.dismissed;
-
-  void _handleOpenDrawer() {
-    setState(() {
-      _drawerShowing = true;
-      _drawerStatus = AnimationStatus.forward;
-    });
-  }
-
-  void _handleDrawerDismissed() {
-    setState(() {
-      _drawerStatus = AnimationStatus.dismissed;
-    });
-  }
-
   void _handleShowSettings() {
     config.navigator.pop();
     config.navigator.pushNamed('/settings');
@@ -137,7 +114,7 @@ class FeedFragmentState extends State<FeedFragment> {
     return new ToolBar(
       left: new IconButton(
         icon: "navigation/menu",
-        onPressed: _handleOpenDrawer),
+        onPressed: _showDrawer),
       center: new Text(fitnessModeTitle)
     );
   }
@@ -149,7 +126,7 @@ class FeedFragmentState extends State<FeedFragment> {
     setState(() {
       _undoItem = item;
       _isShowingSnackBar = true;
-      _snackBarStatus = AnimationStatus.forward;
+      _snackBarStatus = PerformanceStatus.forward;
     });
   }
 
@@ -230,13 +207,13 @@ class FeedFragmentState extends State<FeedFragment> {
   }
 
   Widget buildSnackBar() {
-    if (_snackBarStatus == AnimationStatus.dismissed)
+    if (_snackBarStatus == PerformanceStatus.dismissed)
       return null;
     return new SnackBar(
       showing: _isShowingSnackBar,
       content: new Text("Item deleted."),
       actions: [new SnackBarAction(label: "UNDO", onPressed: _handleUndo)],
-      onDismissed: () { setState(() { _snackBarStatus = AnimationStatus.dismissed; }); }
+      onDismissed: () { setState(() { _snackBarStatus = PerformanceStatus.dismissed; }); }
     );
   }
 
@@ -264,8 +241,7 @@ class FeedFragmentState extends State<FeedFragment> {
       toolbar: buildToolBar(),
       body: buildBody(),
       snackBar: buildSnackBar(),
-      floatingActionButton: buildFloatingActionButton(),
-      drawer: buildDrawer()
+      floatingActionButton: buildFloatingActionButton()
     );
   }
 }

examples/fitness/lib/main.dart

@@ -92,8 +92,6 @@ class FitnessApp extends StatefulComponent {
 class FitnessAppState extends State<FitnessApp> {
   UserDataImpl _userData;
 
-  Map<String, RouteBuilder> _routes;
-
   void initState() {
     super.initState();
     loadFitnessData().then((UserData data) {
@@ -102,36 +100,6 @@ class FitnessAppState extends State<FitnessApp> {
       print("Failed to load data: $e");
       setState(() => _userData = new UserDataImpl());
     });
-
-    _routes = {
-      '/': (NavigatorState navigator, Route route) {
-        return new FeedFragment(
-          navigator: navigator,
-          userData: _userData,
-          onItemCreated: _handleItemCreated,
-          onItemDeleted: _handleItemDeleted
-        );
-      },
-      '/meals/new': (navigator, route) {
-        return new MealFragment(
-          navigator: navigator,
-          onCreated: _handleItemCreated
-        );
-      },
-      '/measurements/new': (NavigatorState navigator, Route route) {
-        return new MeasurementFragment(
-          navigator: navigator,
-          onCreated: _handleItemCreated
-        );
-      },
-      '/settings': (navigator, route) {
-        return new SettingsFragment(
-          navigator: navigator,
-          userData: _userData,
-          updater: settingsUpdater
-        );
-      }
-    };
   }
 
   void _handleItemCreated(FitnessItem item) {
@@ -158,17 +126,43 @@ class FitnessAppState extends State<FitnessApp> {
     });
   }
 
-  final ThemeData _theme = new ThemeData(
+  Widget build(BuildContext) {
+    return new App(
+      theme: new ThemeData(
         brightness: ThemeBrightness.light,
         primarySwatch: Colors.indigo,
         accentColor: Colors.pinkAccent[200]
-  );
-
-  Widget build(BuildContext) {
-    return new App(
-      theme: _theme,
+      ),
       title: 'Fitness',
-      routes: _routes
+      routes: {
+        '/': (RouteArguments args) {
+          return new FeedFragment(
+            navigator: args.navigator,
+            userData: _userData,
+            onItemCreated: _handleItemCreated,
+            onItemDeleted: _handleItemDeleted
+          );
+        },
+        '/meals/new': (RouteArguments args) {
+          return new MealFragment(
+            navigator: args.navigator,
+            onCreated: _handleItemCreated
+          );
+        },
+        '/measurements/new': (RouteArguments args) {
+          return new MeasurementFragment(
+            navigator: args.navigator,
+            onCreated: _handleItemCreated
+          );
+        },
+        '/settings': (RouteArguments args) {
+          return new SettingsFragment(
+            navigator: args.navigator,
+            userData: _userData,
+            updater: settingsUpdater
+          );
+        }
+      }
     );
   }
 }

examples/fitness/lib/meal.dart

@@ -65,12 +65,13 @@ class MealFragmentState extends State<MealFragment> {
         icon: "navigation/close",
         onPressed: config.navigator.pop),
       center: new Text('New Meal'),
-      right: [new InkWell(
-        child: new GestureDetector(
+      right: [
+        // TODO(abarth): Should this be a FlatButton?
+        new InkWell(
           onTap: _handleSave,
           child: new Text('SAVE')
         )
-      )]
+      ]
     );
   }
 

examples/fitness/lib/measurement.dart

@@ -136,12 +136,13 @@ class MeasurementFragmentState extends State<MeasurementFragment> {
         icon: "navigation/close",
         onPressed: config.navigator.pop),
       center: new Text('New Measurement'),
-      right: [new InkWell(
-        child: new GestureDetector(
+      right: [
+        // TODO(abarth): Should this be a FlatButton?
+        new InkWell(
           onTap: _handleSave,
           child: new Text('SAVE')
         )
-      )]
+      ]
     );
   }
 

examples/game/example_effect_line.dart

@@ -62,7 +62,7 @@ class TestAppState extends State<TestApp> {
     );
   }
 
-  Column _buildColumn(NavigatorState navigator, Route route) {
+  Column _buildColumn(RouteArguments args) {
     return new Column([
       new Flexible(child: _buildSpriteWidget()),
       _buildTabBar()

examples/game/lib/main.dart

@@ -92,11 +92,11 @@ class GameDemoState extends State<GameDemo> {
     );
   }
 
-  Widget _buildGameScene(NavigatorState navigator, Route route) {
+  Widget _buildGameScene(RouteArguments args) {
     return new SpriteWidget(_game, SpriteBoxTransformMode.fixedWidth);
   }
 
-  Widget _buildMainScene(navigator, route) {
+  Widget _buildMainScene(RouteArguments args) {
     return new Stack([
       new SpriteWidget(new MainScreenBackground(), SpriteBoxTransformMode.fixedWidth),
       new Column([
@@ -109,10 +109,10 @@ class GameDemoState extends State<GameDemo> {
                 _sounds,
                 (lastScore) {
                   setState(() {_lastScore = lastScore;});
-                  navigator.pop();
+                  args.navigator.pop();
                 }
               );
-              navigator.pushNamed('/game');
+              args.navigator.pushNamed('/game');
             },
             texture: _spriteSheetUI['btn_play_up.png'],
             textureDown: _spriteSheetUI['btn_play_down.png'],

examples/game/pubspec.yaml

@@ -3,6 +3,7 @@ dependencies:
   sky: any
   sky_tools: any
   skysprites: any
+  box2d: any
 dependency_overrides:
   material_design_icons:
     path: ../../sky/packages/material_design_icons

examples/game/test_bed.dart

+import 'dart:sky';
+
+import 'package:sky/material.dart';
+import 'package:sky/rendering.dart';
+import 'package:sky/services.dart';
+import 'package:sky/widgets.dart';
+import 'package:skysprites/skysprites.dart';
+
+AssetBundle _initBundle() {
+  if (rootBundle != null)
+    return rootBundle;
+  return new NetworkAssetBundle(Uri.base);
+}
+
+final AssetBundle _bundle = _initBundle();
+
+ImageMap _images;
+SpriteSheet _spriteSheet;
+TestBedApp _app;
+
+main() async {
+  _images = new ImageMap(_bundle);
+
+  await _images.load([
+    'assets/sprites.png'
+  ]);
+
+  String json = await _bundle.loadString('assets/sprites.json');
+  _spriteSheet = new SpriteSheet(_images['assets/sprites.png'], json);
+
+  _app = new TestBedApp();
+  runApp(_app);
+}
+
+class TestBedApp extends App {
+
+  Widget build() {
+    ThemeData theme = new ThemeData(
+      brightness: ThemeBrightness.light,
+      primarySwatch: Colors.purple
+    );
+
+    return new Theme(
+      data: theme,
+      child: new Title(
+        title: 'Test Bed',
+        child: new SpriteWidget(
+          new TestBed(),
+          SpriteBoxTransformMode.letterbox
+        )
+      )
+    );
+  }
+}
+
+class TestBed extends NodeWithSize {
+  TestBed() : super(new Size(1024.0, 1024.0)) {
+  }
+}

examples/game/test_drawatlas.dart

@@ -36,7 +36,7 @@ main() async {
     title: 'Test drawAtlas',
     theme: _theme,
     routes: {
-      '/': (NavigatorState navigator, Route route) {
+      '/': (RouteArguments args) {
         return new SpriteWidget(
           new TestDrawAtlas(),
           SpriteBoxTransformMode.fixedWidth

examples/game/test_physics.dart

+import 'dart:sky';
+
+import 'package:sky/material.dart';
+import 'package:sky/rendering.dart';
+import 'package:sky/services.dart';
+import 'package:sky/widgets.dart';
+import 'package:skysprites/skysprites.dart';
+
+AssetBundle _initBundle() {
+  if (rootBundle != null)
+    return rootBundle;
+  return new NetworkAssetBundle(Uri.base);
+}
+
+final AssetBundle _bundle = _initBundle();
+
+ImageMap _images;
+SpriteSheet _spriteSheet;
+
+main() async {
+  _images = new ImageMap(_bundle);
+
+  await _images.load([
+    'assets/sprites.png'
+  ]);
+
+  String json = await _bundle.loadString('assets/sprites.json');
+  _spriteSheet = new SpriteSheet(_images['assets/sprites.png'], json);
+
+  runApp(new App(
+    title: 'Test Physics',
+    theme: new ThemeData(
+      brightness: ThemeBrightness.light,
+      primarySwatch: Colors.purple
+    ),
+    routes: {
+      '/': (RouteArguments args) {
+        return new SpriteWidget(
+          new TestBed(),
+          SpriteBoxTransformMode.letterbox
+        );
+      }
+    }
+  ));
+}
+
+class TestBed extends NodeWithSize {
+  Sprite _ship;
+  Sprite _obstacle;
+
+  TestBed() : super(new Size(1024.0, 1024.0)) {
+    PhysicsNode physicsNode = new PhysicsNode(new Offset(0.0, 100.0));
+
+    _ship = new Sprite(_spriteSheet["ship.png"]);
+    _ship.position = new Point(512.0, 512.0);
+    _ship.size = new Size(64.0, 64.0);
+    _ship.physicsBody = new PhysicsBody(
+      new PhysicsShapeGroup([
+        new PhysicsShapeCircle(Point.origin, 32.0),
+        new PhysicsShapePolygon([new Point(0.0, 0.0), new Point(50.0, 0.0), new Point(50.0, 50.0), new Point(0.0, 50.0)])
+      ]),
+      friction: 0.5,
+      tag: "ship"
+    );
+    physicsNode.addChild(_ship);
+
+    _obstacle = new Sprite(_spriteSheet["ship.png"]);
+    _obstacle.position = new Point(532.0, 800.0);
+    _obstacle.size = new Size(64.0, 64.0);
+    _obstacle.physicsBody = new PhysicsBody(
+      new PhysicsShapeCircle(Point.origin, 32.0),
+      type: PhysicsBodyType.static,
+      friction: 0.5,
+      tag: "obstacle"
+    );
+    physicsNode.addChild(_obstacle);
+    physicsNode.addContactCallback(myCallback, "obstacle", "ship", PhysicsContactType.begin);
+
+    addChild(physicsNode);
+
+    userInteractionEnabled = true;
+  }
+
+  void myCallback(PhysicsContactType type, PhysicsContact contact) {
+    print("CONTACT type: $type");
+    contact.nodeB.removeFromParent();
+  }
+
+  bool handleEvent(SpriteBoxEvent event) {
+    if (event.type == "pointerdown") {
+      Point pos = convertPointToNodeSpace(event.boxPosition);
+      _ship.position = pos;
+    }
+    return true;
+  }
+}

examples/mine_digger/lib/main.dart

@@ -64,33 +64,25 @@ class MineDiggerState extends State<MineDigger> {
     alive = true;
     hasWon = false;
     detectedCount = 0;
-    // Build the arrays.
-    cells = new List<List<bool>>();
-    uiState = new List<List<CellState>>();
-    for (int iy = 0; iy != rows; iy++) {
-      cells.add(new List<bool>());
-      uiState.add(new List<CellState>());
-      for (int ix = 0; ix != cols; ix++) {
-        cells[iy].add(false);
-        uiState[iy].add(CellState.covered);
-      }
-    }
+    // Initialize matrices.
+    cells = new List<List>.generate(rows, (int row) {
+      return new List<bool>.filled(cols, false);
+    });
+    uiState = new List<List>.generate(rows, (int row) {
+      return new List<CellState>.filled(cols, CellState.covered);
+    });
     // Place the mines.
     Random random = new Random();
-    int cellsRemaining = rows * cols;
     int minesRemaining = totalMineCount;
-    for (int x = 0; x < cols; x += 1) {
-      for (int y = 0; y < rows; y += 1) {
-        if (random.nextInt(cellsRemaining) < minesRemaining) {
-          cells[y][x] = true;
-          minesRemaining -= 1;
-          if (minesRemaining <= 0)
-            return;
-        }
-        cellsRemaining -= 1;
+    while (minesRemaining > 0) {
+      int pos = random.nextInt(rows * cols);
+      int row = pos ~/ rows;
+      int col = pos % cols;
+      if (!cells[row][col]) {
+        cells[row][col] = true;
+        minesRemaining--;
       }
     }
-    assert(false);
   }
 
   PointerEventListener _pointerDownHandlerFor(int posX, int posY) {
@@ -106,9 +98,9 @@ class MineDiggerState extends State<MineDigger> {
   Widget buildBoard() {
     bool hasCoveredCell = false;
     List<Row> flexRows = <Row>[];
-    for (int iy = 0; iy != 9; iy++) {
+    for (int iy = 0; iy < rows; iy++) {
       List<Widget> row = <Widget>[];
-      for (int ix = 0; ix != 9; ix++) {
+      for (int ix = 0; ix < cols; ix++) {
         CellState state = uiState[iy][ix];
         int count = mineCount(ix, iy);
         if (!alive) {

examples/rendering/spinning_flex.dart

@@ -9,7 +9,7 @@ import 'package:sky/rendering.dart';
 
 import 'solid_color_box.dart';
 
-double timeBase;
+Duration timeBase;
 RenderTransform transformBox;
 
 void main() {
@@ -34,10 +34,10 @@ void main() {
   scheduler.addPersistentFrameCallback(rotate);
 }
 
-void rotate(double timeStamp) {
+void rotate(Duration timeStamp) {
   if (timeBase == null)
     timeBase = timeStamp;
-  double delta = (timeStamp - timeBase) / 1000; // radians
+  double delta = (timeStamp - timeBase).inMicroseconds.toDouble() / Duration.MICROSECONDS_PER_SECOND; // radians
 
   transformBox.setIdentity();
   transformBox.translate(transformBox.size.width / 2.0, transformBox.size.height / 2.0);

examples/stocks/lib/main.dart

@@ -82,7 +82,7 @@ class StocksAppState extends State<StocksApp> {
       if (path.length != 3)
         return null;
       if (_stocks.containsKey(path[2]))
-        return (navigator, route) => new StockSymbolViewer(navigator, _stocks[path[2]]);
+        return (RouteArguments args) => new StockSymbolViewer(args.navigator, _stocks[path[2]]);
       return null;
     }
     return null;
@@ -93,8 +93,8 @@ class StocksAppState extends State<StocksApp> {
       title: 'Stocks',
       theme: theme,
       routes: <String, RouteBuilder>{
-         '/':         (navigator, route) => new StockHome(navigator, _stocks, _symbols, _optimismSetting, modeUpdater),
-         '/settings': (navigator, route) => new StockSettings(navigator, _optimismSetting, _backupSetting, settingsUpdater)
+         '/':         (RouteArguments args) => new StockHome(args.navigator, _stocks, _symbols, _optimismSetting, modeUpdater),
+         '/settings': (RouteArguments args) => new StockSettings(args.navigator, _optimismSetting, _backupSetting, settingsUpdater)
       },
       onGenerateRoute: _getRoute
     );

examples/stocks/lib/stock_home.dart

@@ -25,7 +25,7 @@ class StockHomeState extends State<StockHome> {
   bool _isSearching = false;
   String _searchQuery;
 
-  AnimationStatus _snackBarStatus = AnimationStatus.dismissed;
+  PerformanceStatus _snackBarStatus = PerformanceStatus.dismissed;
   bool _isSnackBarShowing = false;
 
   void _handleSearchBegin() {
@@ -56,22 +56,6 @@ class StockHomeState extends State<StockHome> {
     });
   }
 
-  bool _drawerShowing = false;
-  AnimationStatus _drawerStatus = AnimationStatus.dismissed;
-
-  void _handleOpenDrawer() {
-    setState(() {
-      _drawerShowing = true;
-      _drawerStatus = AnimationStatus.forward;
-    });
-  }
-
-  void _handleDrawerDismissed() {
-    setState(() {
-      _drawerStatus = AnimationStatus.dismissed;
-    });
-  }
-
   bool _autorefresh = false;
   void _handleAutorefreshChanged(bool value) {
     setState(() {
@@ -91,16 +75,10 @@ class StockHomeState extends State<StockHome> {
     );
   }
 
-  Drawer buildDrawer() {
-    if (_drawerStatus == AnimationStatus.dismissed)
-      return null;
-    assert(_drawerShowing); // TODO(mpcomplete): this is always true
-    return new Drawer(
-      level: 3,
-      showing: _drawerShowing,
-      onDismissed: _handleDrawerDismissed,
+  void _showDrawer() {
+    showDrawer(
       navigator: config.navigator,
-      children: [
+      child: new Block([
         new DrawerHeader(child: new Text('Stocks')),
         new DrawerItem(
           icon: 'action/assessment',
@@ -141,7 +119,7 @@ class StockHomeState extends State<StockHome> {
         new DrawerItem(
           icon: 'action/help',
           child: new Text('Help & Feedback'))
-     ]
+      ])
     );
   }
 
@@ -154,7 +132,7 @@ class StockHomeState extends State<StockHome> {
     return new ToolBar(
         left: new IconButton(
           icon: "navigation/menu",
-          onPressed: _handleOpenDrawer
+          onPressed: _showDrawer
         ),
         center: new Text('Stocks'),
         right: [
@@ -246,20 +224,20 @@ class StockHomeState extends State<StockHome> {
 
   GlobalKey snackBarKey = new GlobalKey(label: 'snackbar');
   Widget buildSnackBar() {
-    if (_snackBarStatus == AnimationStatus.dismissed)
+    if (_snackBarStatus == PerformanceStatus.dismissed)
       return null;
     return new SnackBar(
       showing: _isSnackBarShowing,
       content: new Text("Stock purchased!"),
       actions: [new SnackBarAction(label: "UNDO", onPressed: _handleUndo)],
-      onDismissed: () { setState(() { _snackBarStatus = AnimationStatus.dismissed; }); }
+      onDismissed: () { setState(() { _snackBarStatus = PerformanceStatus.dismissed; }); }
     );
   }
 
   void _handleStockPurchased() {
     setState(() {
       _isSnackBarShowing = true;
-      _snackBarStatus = AnimationStatus.forward;
+      _snackBarStatus = PerformanceStatus.forward;
     });
   }
 
@@ -276,8 +254,7 @@ class StockHomeState extends State<StockHome> {
       toolbar: _isSearching ? buildSearchBar() : buildToolBar(),
       body: buildTabNavigator(),
       snackBar: buildSnackBar(),
-      floatingActionButton: buildFloatingActionButton(),
-      drawer: buildDrawer()
+      floatingActionButton: buildFloatingActionButton()
     );
   }
 }

examples/stocks/lib/stock_row.dart

@@ -37,13 +37,13 @@ class StockRow extends StatelessComponent {
 
   static const double kHeight = 79.0;
 
-  GestureTapListener _getTapHandler(StockRowActionCallback callback) {
+  GestureTapCallback _getTapHandler(StockRowActionCallback callback) {
     if (callback == null)
       return null;
     return () => callback(stock, key, arrowKey, symbolKey, priceKey);
   }
 
-  GestureLongPressListener _getLongPressHandler(StockRowActionCallback callback) {
+  GestureLongPressCallback _getLongPressHandler(StockRowActionCallback callback) {
     if (callback == null)
       return null;
     return () => callback(stock, key, arrowKey, symbolKey, priceKey);
@@ -55,10 +55,9 @@ class StockRow extends StatelessComponent {
     String changeInPrice = "${stock.percentChange.toStringAsFixed(2)}%";
     if (stock.percentChange > 0) changeInPrice = "+" + changeInPrice;
 
-    return new GestureDetector(
+    return new InkWell(
       onTap: _getTapHandler(onPressed),
       onLongPress: _getLongPressHandler(onLongPressed),
-      child: new InkWell(
       child: new Container(
         padding: const EdgeDims.TRBL(16.0, 16.0, 20.0, 16.0),
         decoration: new BoxDecoration(
@@ -101,7 +100,6 @@ class StockRow extends StatelessComponent {
           )
         ])
       )
-      )
     );
   }
 }

examples/widgets/card_collection.dart

@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:sky/animation.dart';
+import 'dart:sky' as sky;
+
 import 'package:sky/material.dart';
 import 'package:sky/painting.dart';
 import 'package:sky/widgets.dart';
@@ -16,15 +17,22 @@ class CardModel {
   Key get key => new ObjectKey(this);
 }
 
-class CardCollectionApp extends StatefulComponent {
-  CardCollectionAppState createState() => new CardCollectionAppState();
+class CardCollection extends StatefulComponent {
+  CardCollection({ this.navigator });
+
+  final NavigatorState navigator;
+
+  CardCollectionState createState() => new CardCollectionState();
 }
 
-class CardCollectionAppState extends State<CardCollectionApp> {
+class CardCollectionState extends State<CardCollection> {
 
   static const TextStyle cardLabelStyle =
     const TextStyle(color: Colors.white, fontSize: 18.0, fontWeight: bold);
 
+  // TODO(hansmuller): need a local image asset
+  static const _sunshineURL = "http://www.walltor.com/images/wallpaper/good-morning-sunshine-58540.jpg";
+
   final TextStyle backgroundTextStyle =
     Typography.white.title.copyWith(textAlign: TextAlign.center);
 
@@ -32,8 +40,7 @@ class CardCollectionAppState extends State<CardCollectionApp> {
   DismissDirection _dismissDirection = DismissDirection.horizontal;
   bool _snapToCenter = false;
   bool _fixedSizeCards = false;
-  bool _drawerShowing = false;
-  AnimationStatus _drawerStatus = AnimationStatus.dismissed;
+  bool _sunshine = false;
   InvalidatorCallback _invalidator;
   Size _cardCollectionSize = new Size(200.0, 200.0);
 
@@ -108,17 +115,23 @@ class CardCollectionAppState extends State<CardCollectionApp> {
     }
   }
 
-  void _handleOpenDrawer() {
-    setState(() {
-      _drawerShowing = true;
-      _drawerStatus = AnimationStatus.forward;
-    });
-  }
-
-  void _handleDrawerDismissed() {
-    setState(() {
-      _drawerStatus = AnimationStatus.dismissed;
-    });
+  void _showDrawer() {
+    showDrawer(
+      navigator: config.navigator,
+      child: new IconTheme(
+        data: const IconThemeData(color: IconThemeColor.black),
+        child: new Block([
+          new DrawerHeader(child: new Text('Options')),
+          buildDrawerCheckbox("Snap fling scrolls to center", _snapToCenter, _toggleSnapToCenter),
+          buildDrawerCheckbox("Fixed size cards", _fixedSizeCards, _toggleFixedSizeCards),
+          buildDrawerCheckbox("Let the sun shine", _sunshine, _toggleSunshine),
+          new DrawerDivider(),
+          buildDrawerRadioItem(DismissDirection.horizontal, 'action/code'),
+          buildDrawerRadioItem(DismissDirection.left, 'navigation/arrow_back'),
+          buildDrawerRadioItem(DismissDirection.right, 'navigation/arrow_forward'),
+        ])
+      )
+    );
   }
 
   String _dismissDirectionText(DismissDirection direction) {
@@ -139,16 +152,18 @@ class CardCollectionAppState extends State<CardCollectionApp> {
     });
   }
 
-  _changeDismissDirection(DismissDirection newDismissDirection) {
+  void _toggleSunshine() {
     setState(() {
-      _dismissDirection = newDismissDirection;
-      _drawerStatus = AnimationStatus.dismissed;
+      _sunshine = !_sunshine;
     });
   }
 
-  Widget buildDrawer() {
-    if (_drawerStatus == AnimationStatus.dismissed)
-      return null;
+  void _changeDismissDirection(DismissDirection newDismissDirection) {
+    setState(() {
+      _dismissDirection = newDismissDirection;
+    });
+    config.navigator.pop();
+  }
 
   Widget buildDrawerCheckbox(String label, bool value, Function callback) {
     return new DrawerItem(
@@ -175,28 +190,9 @@ class CardCollectionAppState extends State<CardCollectionApp> {
     );
   }
 
-    return new IconTheme(
-      data: const IconThemeData(color: IconThemeColor.black),
-      child: new Drawer(
-        level: 3,
-        showing: _drawerShowing,
-        onDismissed: _handleDrawerDismissed,
-        children: [
-          new DrawerHeader(child: new Text('Options')),
-          buildDrawerCheckbox("Snap fling scrolls to center", _snapToCenter, _toggleSnapToCenter),
-          buildDrawerCheckbox("Fixed size cards", _fixedSizeCards, _toggleFixedSizeCards),
-          new DrawerDivider(),
-          buildDrawerRadioItem(DismissDirection.horizontal, 'action/code'),
-          buildDrawerRadioItem(DismissDirection.left, 'navigation/arrow_back'),
-          buildDrawerRadioItem(DismissDirection.right, 'navigation/arrow_forward'),
-        ]
-      )
-    );
-  }
-
   Widget buildToolBar() {
     return new ToolBar(
-      left: new IconButton(icon: "navigation/menu", onPressed: _handleOpenDrawer),
+      left: new IconButton(icon: "navigation/menu", onPressed: _showDrawer),
       center: new Text('Swipe Away'),
       right: [
         new Text(_dismissDirectionText(_dismissDirection))
@@ -285,6 +281,16 @@ class CardCollectionAppState extends State<CardCollectionApp> {
     });
   }
 
+  sky.Shader _createShader(Rect bounds) {
+    return new LinearGradient(
+        begin: Point.origin,
+        end: new Point(0.0, bounds.height),
+        colors: [const Color(0x00FFFFFF), const Color(0xFFFFFFFF)],
+        stops: [0.1, 0.35]
+    )
+    .createShader();
+  }
+
   Widget build(BuildContext context) {
 
     Widget cardCollection;
@@ -306,6 +312,12 @@ class CardCollectionAppState extends State<CardCollectionApp> {
       );
     }
 
+    if (_sunshine)
+      cardCollection = new Stack([
+        new Column([new NetworkImage(src: _sunshineURL)]),
+        new ShaderMask(child: cardCollection, shaderCallback: _createShader)
+      ]);
+
     Widget body = new SizeObserver(
       callback: _updateCardCollectionSize,
       child: new Container(
@@ -329,24 +341,23 @@ class CardCollectionAppState extends State<CardCollectionApp> {
       body = new Stack([body, indicator]);
     }
 
-    return new Theme(
-      data: new ThemeData(
-        brightness: ThemeBrightness.light,
-        primarySwatch: Colors.blue,
-        accentColor: Colors.redAccent[200]
-      ),
-      child: new Title(
-        title: 'Cards',
-        child: new Scaffold(
+    return new Scaffold(
       toolbar: buildToolBar(),
-          drawer: buildDrawer(),
       body: body
-        )
-      )
     );
   }
 }
 
 void main() {
-  runApp(new CardCollectionApp());
+  runApp(new App(
+    title: 'Cards',
+    theme: new ThemeData(
+      brightness: ThemeBrightness.light,
+      primarySwatch: Colors.blue,
+      accentColor: Colors.redAccent[200]
+    ),
+    routes: {
+      '/': (RouteArguments args) => new CardCollection(navigator: args.navigator),
+    }
+  ));
 }

examples/widgets/drag_and_drop.dart

@@ -50,7 +50,7 @@ class ExampleDragTargetState extends State<ExampleDragTarget> {
 }
 
 class Dot extends StatelessComponent {
-  Dot({ Key key, this.color, this.size }): super(key: key);
+  Dot({ Key key, this.color, this.size }) : super(key: key);
   final Color color;
   final double size;
   Widget build(BuildContext context) {
@@ -66,7 +66,7 @@ class Dot extends StatelessComponent {
 }
 
 class ExampleDragSource extends StatelessComponent {
-  ExampleDragSource({ Key key, this.navigator, this.name, this.color }): super(key: key);
+  ExampleDragSource({ Key key, this.navigator, this.name, this.color }) : super(key: key);
   final NavigatorState navigator;
   final String name;
   final Color color;
@@ -133,7 +133,7 @@ void main() {
   runApp(new App(
     title: 'Drag and Drop Flutter Demo',
     routes: {
-     '/': (NavigatorState navigator, Route route) => new DragAndDropApp(navigator: navigator)
+     '/': (RouteArguments args) => new DragAndDropApp(navigator: args.navigator)
     }
   ));
 }

examples/widgets/navigation.dart

@@ -6,46 +6,46 @@ import 'package:sky/material.dart';
 import 'package:sky/widgets.dart';
 
 final Map<String, RouteBuilder> routes = <String, RouteBuilder>{
-  '/': (NavigatorState navigator, Route route) => new Container(
+  '/': (RouteArguments args) => new Container(
     padding: const EdgeDims.all(30.0),
     decoration: new BoxDecoration(backgroundColor: const Color(0xFFCCCCCC)),
     child: new Column([
       new Text("You are at home"),
       new RaisedButton(
         child: new Text('GO SHOPPING'),
-        onPressed: () => navigator.pushNamed('/shopping')
+        onPressed: () => args.navigator.pushNamed('/shopping')
       ),
       new RaisedButton(
         child: new Text('START ADVENTURE'),
-        onPressed: () => navigator.pushNamed('/adventure')
+        onPressed: () => args.navigator.pushNamed('/adventure')
       )],
       justifyContent: FlexJustifyContent.center
     )
   ),
-  '/shopping': (NavigatorState navigator, Route route) => new Container(
+  '/shopping': (RouteArguments args) => new Container(
     padding: const EdgeDims.all(20.0),
     decoration: new BoxDecoration(backgroundColor: const Color(0xFFBF5FFF)),
     child: new Column([
       new Text("Village Shop"),
       new RaisedButton(
         child: new Text('RETURN HOME'),
-        onPressed: () => navigator.pop()
+        onPressed: () => args.navigator.pop()
       ),
       new RaisedButton(
         child: new Text('GO TO DUNGEON'),
-        onPressed: () => navigator.pushNamed('/adventure')
+        onPressed: () => args.navigator.pushNamed('/adventure')
       )],
       justifyContent: FlexJustifyContent.center
     )
   ),
-  '/adventure': (NavigatorState navigator, Route route) => new Container(
+  '/adventure': (RouteArguments args) => new Container(
     padding: const EdgeDims.all(20.0),
     decoration: new BoxDecoration(backgroundColor: const Color(0xFFDC143C)),
     child: new Column([
       new Text("Monster's Lair"),
       new RaisedButton(
         child: new Text('RUN!!!'),
-        onPressed: () => navigator.pop()
+        onPressed: () => args.navigator.pop()
       )],
       justifyContent: FlexJustifyContent.center
     )

examples/widgets/overlay_geometry.dart

@@ -165,7 +165,7 @@ void main() {
     ),
     title: 'Cards',
     routes: {
-      '/': (navigator, route) => new OverlayGeometryApp()
+      '/': (RouteArguments args) => new OverlayGeometryApp()
     }
   ));
 }

examples/widgets/pageable_list.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:sky/animation.dart';
 import 'package:sky/material.dart';
 import 'package:sky/painting.dart';
 import 'package:sky/widgets.dart';
@@ -17,6 +16,10 @@ class CardModel {
 }
 
 class PageableListApp extends StatefulComponent {
+  PageableListApp({ this.navigator });
+
+  final NavigatorState navigator;
+
   PageableListAppState createState() => new PageableListAppState();
 }
 
@@ -85,31 +88,10 @@ class PageableListAppState extends State<PageableListApp> {
     });
   }
 
-  bool _drawerShowing = false;
-  AnimationStatus _drawerStatus = AnimationStatus.dismissed;
-
-  void _handleOpenDrawer() {
-    setState(() {
-      _drawerShowing = true;
-      _drawerStatus = AnimationStatus.forward;
-    });
-  }
-
-  void _handleDrawerDismissed() {
-    setState(() {
-      _drawerStatus = AnimationStatus.dismissed;
-    });
-  }
-
-  Drawer buildDrawer() {
-    if (_drawerStatus == AnimationStatus.dismissed)
-      return null;
-
-    return new Drawer(
-      level: 3,
-      showing: _drawerShowing,
-      onDismissed: _handleDrawerDismissed,
-      children: [
+  void _showDrawer() {
+    showDrawer(
+      navigator: config.navigator,
+      child: new Block([
         new DrawerHeader(child: new Text('Options')),
         new DrawerItem(
           icon: 'navigation/more_horiz',
@@ -130,14 +112,13 @@ class PageableListAppState extends State<PageableListApp> {
             new Checkbox(value: itemsWrap)
           ])
         )
-      ]
+      ])
     );
-
   }
 
   Widget buildToolBar() {
     return new ToolBar(
-      left: new IconButton(icon: "navigation/menu", onPressed: _handleOpenDrawer),
+      left: new IconButton(icon: "navigation/menu", onPressed: _showDrawer),
       center: new Text('PageableList'),
       right: [
         new Text(scrollDirection == ScrollDirection.horizontal ? "horizontal" : "vertical")
@@ -167,25 +148,24 @@ class PageableListAppState extends State<PageableListApp> {
   Widget build(BuildContext context) {
     return new IconTheme(
       data: const IconThemeData(color: IconThemeColor.white),
-      child: new Theme(
-        data: new ThemeData(
-          brightness: ThemeBrightness.light,
-          primarySwatch: Colors.blue,
-          accentColor: Colors.redAccent[200]
-        ),
-        child: new Title(
-          title: 'PageableList',
       child: new Scaffold(
-            drawer: buildDrawer(),
         toolbar: buildToolBar(),
         body: buildBody(context)
       )
-        )
-      )
     );
   }
 }
 
 void main() {
-  runApp(new PageableListApp());
+  runApp(new App(
+    title: 'PageableList',
+    theme: new ThemeData(
+      brightness: ThemeBrightness.light,
+      primarySwatch: Colors.blue,
+      accentColor: Colors.redAccent[200]
+    ),
+    routes: {
+      '/': (RouteArguments args) => new PageableListApp(navigator: args.navigator),
+    }
+  ));
 }

examples/widgets/progress_indicator.dart

@@ -13,24 +13,23 @@ class ProgressIndicatorApp extends StatefulComponent {
 class ProgressIndicatorAppState extends State<ProgressIndicatorApp> {
   void initState() {
     super.initState();
-    valueAnimation = new ValueAnimation<double>()
+    valueAnimation = new ValuePerformance<double>()
       ..duration = const Duration(milliseconds: 1500)
       ..variable = new AnimatedValue<double>(
         0.0,
         end: 1.0,
-        curve: ease,
-        reverseCurve: ease,
-        interval: new Interval(0.0, 0.9)
+        curve: new Interval(0.0, 0.9, curve: ease),
+        reverseCurve: ease
       );
-    valueAnimation.addStatusListener((AnimationStatus status) {
-      if (status == AnimationStatus.dismissed || status == AnimationStatus.completed)
+    valueAnimation.addStatusListener((PerformanceStatus status) {
+      if (status == PerformanceStatus.dismissed || status == PerformanceStatus.completed)
         reverseValueAnimationDirection();
     });
     valueAnimation.play(valueAnimationDirection);
   }
 
-  ValueAnimation<double> valueAnimation;
-  Direction valueAnimationDirection = Direction.forward;
+  ValuePerformance<double> valueAnimation;
+  AnimationDirection valueAnimationDirection = AnimationDirection.forward;
 
   void handleTap() {
     setState(() {
@@ -43,9 +42,9 @@ class ProgressIndicatorAppState extends State<ProgressIndicatorApp> {
   }
 
   void reverseValueAnimationDirection() {
-    valueAnimationDirection = (valueAnimationDirection == Direction.forward)
-      ? Direction.reverse
-      : Direction.forward;
+    valueAnimationDirection = (valueAnimationDirection == AnimationDirection.forward)
+      ? AnimationDirection.reverse
+      : AnimationDirection.forward;
     valueAnimation.play(valueAnimationDirection);
   }
 

examples/widgets/spinning_mixed.dart

@@ -54,13 +54,13 @@ Widget builder() {
   );
 }
 
-double timeBase;
+Duration timeBase;
 RenderTransform transformBox;
 
-void rotate(double timeStamp) {
+void rotate(Duration timeStamp) {
   if (timeBase == null)
     timeBase = timeStamp;
-  double delta = (timeStamp - timeBase) / 1000; // radians
+  double delta = (timeStamp - timeBase).inMicroseconds.toDouble() / Duration.MICROSECONDS_PER_SECOND; // radians
 
   transformBox.setIdentity();
   transformBox.translate(transformBox.size.width / 2.0, transformBox.size.height / 2.0);

packages/flutter/lib/animation.dart

@@ -7,12 +7,12 @@
 /// This library depends only on core Dart libraries and the `newton` package.
 library animation;
 
-export 'src/animation/animated_simulation.dart';
 export 'src/animation/animated_value.dart';
-export 'src/animation/animation_performance.dart';
+export 'src/animation/performance.dart';
 export 'src/animation/clamped_simulation.dart';
 export 'src/animation/curves.dart';
 export 'src/animation/forces.dart';
 export 'src/animation/scheduler.dart';
 export 'src/animation/scroll_behavior.dart';
-export 'src/animation/timeline.dart';
+export 'src/animation/simulation_stepper.dart';
+export 'src/animation/ticker.dart';

packages/flutter/lib/src/animation/animated_value.dart

@@ -2,12 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import "dart:sky";
+import 'dart:sky' show Color, Rect;
 
 import 'package:sky/src/animation/curves.dart';
 
 /// The direction in which an animation is running
-enum Direction {
+enum AnimationDirection {
   /// The animation is running from beginning to end
   forward,
 
@@ -17,71 +17,51 @@ enum Direction {
 
 /// An interface describing a variable that changes as an animation progresses.
 ///
-/// AnimatedVariables, by convention, must be cheap to create. This allows them to be used in 
-/// build functions in Widgets.
-abstract class AnimatedVariable {
+/// Animatable objects, by convention, must be cheap to create. This allows them
+/// to be used in build functions in Widgets.
+abstract class Animatable {
   /// Update the variable to a given time in an animation that is running in the given direction
-  void setProgress(double t, Direction direction);
+  void setProgress(double t, AnimationDirection direction);
   String toString();
 }
 
-/// Used by [AnimationPerformance] to convert the timing of a performance to a different timescale.
+/// Used by [Performance] to convert the timing of a performance to a different timescale.
 /// For example, by setting different values for the interval and reverseInterval, a performance
 /// can be made to take longer in one direction that the other.
 class AnimationTiming {
-  AnimationTiming({
-    this.interval: const Interval(0.0, 1.0),
-    this.reverseInterval,
-    this.curve: linear,
-    this.reverseCurve
-  });
+  AnimationTiming({ this.curve, this.reverseCurve });
 
-  /// The interval during which this timing is active in the forward direction
-  Interval interval;
-
-  /// The interval during which this timing is active in the reverse direction
-  ///
-  /// If this field is null, the timing defaults to using [interval] in both directions.
-  Interval reverseInterval;
-
-  /// The curve that this timing applies to the animation clock in the forward direction
+  /// The curve to use in the forward direction
   Curve curve;
 
-  /// The curve that this timing applies to the animation clock in the reverse direction
+  /// The curve to use in the reverse direction
   ///
-  /// If this field is null, the timing defaults to using [curve] in both directions.
+  /// If this field is null, use [curve] in both directions.
   Curve reverseCurve;
 
   /// Applies this timing to the given animation clock value in the given direction
-  double transform(double t, Direction direction) {
-    Interval interval = _getInterval(direction);
-    if (interval != null)
-      t = interval.transform(t);
-    if (t == 1.0) // Or should we support inverse curves?
+  double transform(double t, AnimationDirection direction) {
+    Curve activeCurve = _getActiveCurve(direction);
+    if (activeCurve == null)
       return t;
-    Curve curve = _getCurve(direction);
-    if (curve != null)
-      t = curve.transform(t);
+    if (t == 0.0 || t == 1.0) {
+      assert(activeCurve.transform(t).round() == t);
       return t;
     }
-
-  Interval _getInterval(Direction direction) {
-    if (direction == Direction.forward || reverseInterval == null)
-      return interval;
-    return reverseInterval;
+    return activeCurve.transform(t);
   }
 
-  Curve _getCurve(Direction direction) {
-    if (direction == Direction.forward || reverseCurve == null)
+  Curve _getActiveCurve(AnimationDirection direction) {
+    if (direction == AnimationDirection.forward || reverseCurve == null)
       return curve;
     return reverseCurve;
   }
 }
 
 /// An animated variable with a concrete type
-class AnimatedValue<T extends dynamic> extends AnimationTiming implements AnimatedVariable {
-  AnimatedValue(this.begin, { this.end, Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
-    : super(interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve) {
+class AnimatedValue<T extends dynamic> extends AnimationTiming implements Animatable {
+  AnimatedValue(this.begin, { this.end, Curve curve, Curve reverseCurve })
+    : super(curve: curve, reverseCurve: reverseCurve) {
     value = begin;
   }
 
@@ -98,41 +78,28 @@ class AnimatedValue<T extends dynamic> extends AnimationTiming implements Animat
   T lerp(double t) => begin + (end - begin) * t;
 
   /// Updates the value of this variable according to the given animation clock value and direction
-  void setProgress(double t, Direction direction) {
+  void setProgress(double t, AnimationDirection direction) {
     if (end != null) {
       t = transform(t, direction);
-      value = (t == 1.0) ? end : lerp(t);
+      if (t == 0.0)
+        value = begin;
+      else if (t == 1.0)
+        value = end;
+      else
+        value = lerp(t);
     }
   }
 
   String toString() => 'AnimatedValue(begin=$begin, end=$end, value=$value)';
 }
 
-/// A list of animated variables
-class AnimatedList extends AnimationTiming implements AnimatedVariable {
-  /// The list of variables contained in the list
-  List<AnimatedVariable> variables;
-
-  AnimatedList(this.variables, { Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
-    : super(interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve);
-
-  // Updates the value of all the variables in the list according to the given animation clock value and direction
-  void setProgress(double t, Direction direction) {
-    double adjustedTime = transform(t, direction);
-    for (AnimatedVariable variable in variables)
-      variable.setProgress(adjustedTime, direction);
-  }
-
-  String toString() => 'AnimatedList([$variables])';
-}
-
 /// An animated variable containing a color
 ///
 /// This class specializes the interpolation of AnimatedValue<Color> to be
 /// appropriate for colors.
 class AnimatedColorValue extends AnimatedValue<Color> {
-  AnimatedColorValue(Color begin, { Color end, Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
-    : super(begin, end: end, interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve);
+  AnimatedColorValue(Color begin, { Color end, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
 
   Color lerp(double t) => Color.lerp(begin, end, t);
 }
@@ -141,9 +108,9 @@ class AnimatedColorValue extends AnimatedValue<Color> {
 ///
 /// This class specializes the interpolation of AnimatedValue<Rect> to be
 /// appropriate for rectangles.
-class AnimatedRect extends AnimatedValue<Rect> {
-  AnimatedRect(Rect begin, { Rect end, Interval interval, Interval reverseInterval, Curve curve, Curve reverseCurve })
-    : super(begin, end: end, interval: interval, reverseInterval: reverseInterval, curve: curve, reverseCurve: reverseCurve);
+class AnimatedRectValue extends AnimatedValue<Rect> {
+  AnimatedRectValue(Rect begin, { Rect end, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
 
   Rect lerp(double t) => Rect.lerp(begin, end, t);
 }

packages/flutter/lib/src/animation/curves.dart

@@ -27,9 +27,9 @@ class Linear implements Curve {
   double transform(double t) => t;
 }
 
-/// A curve that is 0.0 until start, then linear from 0.0 to 1.0 at end, then 1.0
+/// A curve that is 0.0 until start, then curved from 0.0 to 1.0 at end, then 1.0
 class Interval implements Curve {
-  const Interval(this.start, this.end);
+  const Interval(this.start, this.end, { this.curve: linear });
 
   /// The smallest value for which this interval is 0.0
   final double start;
@@ -37,12 +37,18 @@ class Interval implements Curve {
   /// The smallest value for which this interval is 1.0
   final double end;
 
+  /// The curve to apply between [start] and [end]
+  final Curve curve;
+
   double transform(double t) {
     assert(start >= 0.0);
     assert(start <= 1.0);
     assert(end >= 0.0);
     assert(end <= 1.0);
-    return ((t - start) / (end - start)).clamp(0.0, 1.0);
+    t = ((t - start) / (end - start)).clamp(0.0, 1.0);
+    if (t == 0.0 || t == 1.0)
+      return t;
+    return curve.transform(t);
   }
 }
 

packages/flutter/lib/src/animation/animation_performance.dart → packages/flutter/lib/src/animation/performance.dart

@@ -6,10 +6,10 @@ import 'dart:async';
 
 import 'package:sky/src/animation/animated_value.dart';
 import 'package:sky/src/animation/forces.dart';
-import 'package:sky/src/animation/timeline.dart';
+import 'package:sky/src/animation/simulation_stepper.dart';
 
 /// The status of an animation
-enum AnimationStatus {
+enum PerformanceStatus {
   /// The animation is stopped at the beginning
   dismissed,
 
@@ -23,27 +23,27 @@ enum AnimationStatus {
   completed,
 }
 
-typedef void AnimationPerformanceListener();
-typedef void AnimationPerformanceStatusListener(AnimationStatus status);
+typedef void PerformanceListener();
+typedef void PerformanceStatusListener(PerformanceStatus status);
 
-/// An interface that is implemented by [AnimationPerformance] that exposes a
+/// An interface that is implemented by [Performance] that exposes a
 /// read-only view of the underlying performance. This is used by classes that
 /// want to watch a performance but should not be able to change the
 /// performance's state.
-abstract class WatchableAnimationPerformance {
+abstract class PerformanceView {
   /// Update the given variable according to the current progress of the performance
-  void updateVariable(AnimatedVariable variable);
+  void updateVariable(Animatable variable);
   /// Calls the listener every time the progress of the performance changes
-  void addListener(AnimationPerformanceListener listener);
+  void addListener(PerformanceListener listener);
   /// Stop calling the listener every time the progress of the performance changes
-  void removeListener(AnimationPerformanceListener listener);
+  void removeListener(PerformanceListener listener);
   /// Calls listener every time the status of the performance changes
-  void addStatusListener(AnimationPerformanceStatusListener listener);
+  void addStatusListener(PerformanceStatusListener listener);
   /// Stops calling the listener every time the status of the performance changes
-  void removeStatusListener(AnimationPerformanceStatusListener listener);
+  void removeStatusListener(PerformanceStatusListener listener);
 }
 
-/// A timeline that can be reversed and used to update [AnimatedVariable]s.
+/// A timeline that can be reversed and used to update [Animatable]s.
 ///
 /// For example, a performance may handle an animation of a menu opening by
 /// sliding and fading in (changing Y value and opacity) over .5 seconds. The
@@ -51,41 +51,38 @@ abstract class WatchableAnimationPerformance {
 /// may also take direct control of the timeline by manipulating [progress], or
 /// [fling] the timeline causing a physics-based simulation to take over the
 /// progression.
-class AnimationPerformance implements WatchableAnimationPerformance {
-  AnimationPerformance({ this.duration, double progress }) {
-    _timeline = new Timeline(_tick);
+class Performance implements PerformanceView {
+  Performance({ this.duration, double progress }) {
+    _timeline = new SimulationStepper(_tick);
     if (progress != null)
       _timeline.value = progress.clamp(0.0, 1.0);
   }
 
-  /// Returns a [WatchableAnimationPerformance] for this performance,
+  /// Returns a [PerformanceView] for this performance,
   /// so that a pointer to this object can be passed around without
   /// allowing users of that pointer to mutate the AnimationPerformance state.
-  WatchableAnimationPerformance get view => this;
+  PerformanceView get view => this;
 
   /// The length of time this performance should last
   Duration duration;
 
-  Timeline _timeline;
-  Direction _direction;
+  SimulationStepper _timeline;
+  AnimationDirection _direction;
 
   /// The direction used to select the current curve
   ///
   /// Curve direction is only reset when we hit the beginning or the end of the
   /// timeline to avoid discontinuities in the value of any variables this
   /// performance is used to animate.
-  Direction _curveDirection;
+  AnimationDirection _curveDirection;
 
   /// If non-null, animate with this timing instead of a linear timing
   AnimationTiming timing;
 
-  /// If non-null, animate with this force instead of a zero-to-one timeline.
-  Force attachedForce;
-
   /// The progress of this performance along the timeline
   ///
   /// Note: Setting this value stops the current animation.
-  double get progress => _timeline.value;
+  double get progress => _timeline.value.clamp(0.0, 1.0);
   void set progress(double t) {
     // TODO(mpcomplete): should this affect |direction|?
     stop();
@@ -98,51 +95,45 @@ class AnimationPerformance implements WatchableAnimationPerformance {
   }
 
   /// Whether this animation is stopped at the beginning
-  bool get isDismissed => status == AnimationStatus.dismissed;
+  bool get isDismissed => status == PerformanceStatus.dismissed;
 
   /// Whether this animation is stopped at the end
-  bool get isCompleted => status == AnimationStatus.completed;
+  bool get isCompleted => status == PerformanceStatus.completed;
 
   /// Whether this animation is currently animating in either the forward or reverse direction
   bool get isAnimating => _timeline.isAnimating;
 
   /// The current status of this animation
-  AnimationStatus get status {
+  PerformanceStatus get status {
     if (!isAnimating && progress == 1.0)
-      return AnimationStatus.completed;
+      return PerformanceStatus.completed;
     if (!isAnimating && progress == 0.0)
-      return AnimationStatus.dismissed;
-    return _direction == Direction.forward ?
-        AnimationStatus.forward :
-        AnimationStatus.reverse;
+      return PerformanceStatus.dismissed;
+    return _direction == AnimationDirection.forward ?
+        PerformanceStatus.forward :
+        PerformanceStatus.reverse;
   }
 
   /// Update the given varaible according to the current progress of this performance
-  void updateVariable(AnimatedVariable variable) {
+  void updateVariable(Animatable variable) {
     variable.setProgress(_curvedProgress, _curveDirection);
   }
 
   /// Start running this animation forwards (towards the end)
-  Future forward() => play(Direction.forward);
+  Future forward() => play(AnimationDirection.forward);
 
   /// Start running this animation in reverse (towards the beginning)
-  Future reverse() => play(Direction.reverse);
+  Future reverse() => play(AnimationDirection.reverse);
 
   /// Start running this animation in the given direction
-  Future play([Direction direction = Direction.forward]) {
+  Future play([AnimationDirection direction = AnimationDirection.forward]) {
     _direction = direction;
     return resume();
   }
 
-  /// Start running this animation in the most recently direction
+  /// Start running this animation in the most recent direction
   Future resume() {
-    if (attachedForce != null) {
-      return fling(
-        velocity: _direction == Direction.forward ? 1.0 : -1.0,
-        force: attachedForce
-      );
-    }
-    return _animateTo(_direction == Direction.forward ? 1.0 : 0.0);
+    return _animateTo(_direction == AnimationDirection.forward ? 1.0 : 0.0);
   }
 
   /// Stop running this animation
@@ -158,46 +149,46 @@ class AnimationPerformance implements WatchableAnimationPerformance {
   Future fling({double velocity: 1.0, Force force}) {
     if (force == null)
       force = kDefaultSpringForce;
-    _direction = velocity < 0.0 ? Direction.reverse : Direction.forward;
-    return _timeline.fling(force.release(progress, velocity));
+    _direction = velocity < 0.0 ? AnimationDirection.reverse : AnimationDirection.forward;
+    return _timeline.animateWith(force.release(progress, velocity));
   }
 
-  final List<AnimationPerformanceListener> _listeners = new List<AnimationPerformanceListener>();
+  final List<PerformanceListener> _listeners = new List<PerformanceListener>();
 
   /// Calls the listener every time the progress of this performance changes
-  void addListener(AnimationPerformanceListener listener) {
+  void addListener(PerformanceListener listener) {
     _listeners.add(listener);
   }
 
   /// Stop calling the listener every time the progress of this performance changes
-  void removeListener(AnimationPerformanceListener listener) {
+  void removeListener(PerformanceListener listener) {
     _listeners.remove(listener);
   }
 
   void _notifyListeners() {
-    List<AnimationPerformanceListener> localListeners = new List<AnimationPerformanceListener>.from(_listeners);
-    for (AnimationPerformanceListener listener in localListeners)
+    List<PerformanceListener> localListeners = new List<PerformanceListener>.from(_listeners);
+    for (PerformanceListener listener in localListeners)
       listener();
   }
 
-  final List<AnimationPerformanceStatusListener> _statusListeners = new List<AnimationPerformanceStatusListener>();
+  final List<PerformanceStatusListener> _statusListeners = new List<PerformanceStatusListener>();
 
   /// Calls listener every time the status of this performance changes
-  void addStatusListener(AnimationPerformanceStatusListener listener) {
+  void addStatusListener(PerformanceStatusListener listener) {
     _statusListeners.add(listener);
   }
 
   /// Stops calling the listener every time the status of this performance changes
-  void removeStatusListener(AnimationPerformanceStatusListener listener) {
+  void removeStatusListener(PerformanceStatusListener listener) {
     _statusListeners.remove(listener);
   }
 
-  AnimationStatus _lastStatus = AnimationStatus.dismissed;
+  PerformanceStatus _lastStatus = PerformanceStatus.dismissed;
   void _checkStatusChanged() {
-    AnimationStatus currentStatus = status;
+    PerformanceStatus currentStatus = status;
     if (currentStatus != _lastStatus) {
-      List<AnimationPerformanceStatusListener> localListeners = new List<AnimationPerformanceStatusListener>.from(_statusListeners);
-      for (AnimationPerformanceStatusListener listener in localListeners)
+      List<PerformanceStatusListener> localListeners = new List<PerformanceStatusListener>.from(_statusListeners);
+      for (PerformanceStatusListener listener in localListeners)
         listener(currentStatus);
     }
     _lastStatus = currentStatus;
@@ -205,7 +196,7 @@ class AnimationPerformance implements WatchableAnimationPerformance {
 
   void _updateCurveDirection() {
     if (status != _lastStatus) {
-      if (_lastStatus == AnimationStatus.dismissed || _lastStatus == AnimationStatus.completed)
+      if (_lastStatus == PerformanceStatus.dismissed || _lastStatus == PerformanceStatus.completed)
         _curveDirection = _direction;
     }
   }
@@ -230,8 +221,8 @@ class AnimationPerformance implements WatchableAnimationPerformance {
 }
 
 /// An animation performance with an animated variable with a concrete type
-class ValueAnimation<T> extends AnimationPerformance {
-  ValueAnimation({ this.variable, Duration duration, double progress }) :
+class ValuePerformance<T> extends Performance {
+  ValuePerformance({ this.variable, Duration duration, double progress }) :
     super(duration: duration, progress: progress);
 
   AnimatedValue<T> variable;

packages/flutter/lib/src/animation/scheduler.dart

@@ -14,7 +14,7 @@ double timeDilation = 1.0;
 /// scheduler's epoch. Use timeStamp to determine how far to advance animation
 /// timelines so that all the animations in the system are synchronized to a
 /// common time base.
-typedef void SchedulerCallback(double timeStamp);
+typedef void SchedulerCallback(Duration timeStamp);
 
 /// Schedules callbacks to run in concert with the engine's animation system
 class Scheduler {
@@ -35,8 +35,10 @@ class Scheduler {
   /// This function first calls all the callbacks registered by
   /// [requestAnimationFrame] and then calls all the callbacks registered by
   /// [addPersistentFrameCallback], which typically drive the rendering pipeline.
-  void beginFrame(double timeStamp) {
-    timeStamp /= timeDilation;
+  void beginFrame(double timeStampMS) {
+    timeStampMS /= timeDilation;
+
+    Duration timeStamp = new Duration(microseconds: (timeStampMS * Duration.MICROSECONDS_PER_MILLISECOND).round());
 
     _haveScheduledVisualUpdate = false;
 

packages/flutter/lib/src/animation/timeline.dart → packages/flutter/lib/src/animation/simulation_stepper.dart

@@ -5,30 +5,31 @@
 import 'dart:async';
 
 import 'package:newton/newton.dart';
-
-import 'package:sky/src/animation/animated_simulation.dart';
-
-/// A simulation that linearly varies from [begin] to [end] over [duration]
-class TweenSimulation extends Simulation {
-  final double _durationInSeconds;
-
-  /// The initial value of the simulation
-  final double begin;
-
-  /// The terminal value of the simulation
-  final double end;
-
-  TweenSimulation(Duration duration, this.begin, this.end) :
-      _durationInSeconds = duration.inMicroseconds / Duration.MICROSECONDS_PER_SECOND {
+import 'package:sky/src/animation/animated_value.dart';
+import 'package:sky/src/animation/curves.dart';
+import 'package:sky/src/animation/ticker.dart';
+
+/// A simulation that varies from [begin] to [end] over [duration] using [curve]
+///
+/// This class is an adaptor between the Simulation interface and the
+/// AnimatedValue interface.
+class _TweenSimulation extends Simulation {
+  _TweenSimulation(double begin, double end, Duration duration, Curve curve)
+    : _durationInSeconds = duration.inMicroseconds.toDouble() / Duration.MICROSECONDS_PER_SECOND,
+      _tween = new AnimatedValue<double>(begin, end: end, curve: curve) {
     assert(_durationInSeconds > 0.0);
-    assert(begin != null && begin >= 0.0 && begin <= 1.0);
-    assert(end != null && end >= 0.0 && end <= 1.0);
+    assert(begin != null);
+    assert(end != null);
   }
 
+  final double _durationInSeconds;
+  final AnimatedValue<double> _tween;
+
   double x(double timeInSeconds) {
     assert(timeInSeconds >= 0.0);
-    final double t = timeInSeconds / _durationInSeconds;
-    return t >= 1.0 ? end : begin + (end - begin) * t;
+    final double t = (timeInSeconds / _durationInSeconds).clamp(0.0, 1.0);
+    _tween.setProgress(t, AnimationDirection.forward);
+    return _tween.value;
   }
 
   double dx(double timeInSeconds) => 1.0;
@@ -36,52 +37,69 @@ class TweenSimulation extends Simulation {
   bool isDone(double timeInSeconds) => timeInSeconds > _durationInSeconds;
 }
 
-/// A timeline for an animation
-class Timeline {
-  Timeline(Function onTick) {
-    _animation = new AnimatedSimulation(onTick);
+typedef TimelineCallback(double value);
+
+/// Steps a simulation one per frame
+class SimulationStepper {
+  SimulationStepper(TimelineCallback onTick) : _onTick = onTick {
+    _ticker = new Ticker(_tick);
   }
 
-  AnimatedSimulation _animation;
+  final TimelineCallback _onTick;
+  Ticker _ticker;
+  Simulation _simulation;
 
   /// The current value of the timeline
-  double get value => _animation.value.clamp(0.0, 1.0);
+  double get value => _value;
+  double _value = 0.0;
   void set value(double newValue) {
-    assert(newValue != null && newValue >= 0.0 && newValue <= 1.0);
+    assert(newValue != null);
     assert(!isAnimating);
-    _animation.value = newValue;
+    _value = newValue;
+    _onTick(_value);
   }
 
   /// Whether the timeline is currently animating
-  bool get isAnimating => _animation.isAnimating;
-
-  Future _start({
-    Duration duration,
-    double begin: 0.0,
-    double end: 1.0
-  }) {
-    assert(!_animation.isAnimating);
-    assert(duration > Duration.ZERO);
-    return _animation.start(new TweenSimulation(duration, begin, end));
-  }
+  bool get isAnimating => _ticker.isTicking;
 
   /// Animate value of the timeline to the given target over the given duration
   ///
   /// Returns a future that resolves when the timeline stops animating,
   /// typically when the timeline arives at the target value.
-  Future animateTo(double target, { Duration duration }) {
+  Future animateTo(double target, { Duration duration, Curve curve: linear }) {
     assert(duration > Duration.ZERO);
-    return _start(duration: duration, begin: value, end: target);
+    assert(!isAnimating);
+    return _start(new _TweenSimulation(value, target, duration, curve));
+  }
+
+  /// Gives the given simulation control over the timeline
+  Future animateWith(Simulation simulation) {
+    stop();
+    return _start(simulation);
+  }
+
+  /// Start ticking the given simulation once per frame
+  ///
+  /// Returns a future that resolves when the simulation stops ticking.
+  Future _start(Simulation simulation) {
+    assert(simulation != null);
+    assert(!isAnimating);
+    _simulation = simulation;
+    _value = simulation.x(0.0);
+    return _ticker.start();
   }
 
   /// Stop animating the timeline
   void stop() {
-    _animation.stop();
+    _simulation = null;
+    _ticker.stop();
   }
 
-  // Gives the given simulation control over the timeline
-  Future fling(Simulation simulation) {
+  void _tick(Duration elapsed) {
+    double elapsedInSeconds = elapsed.inMicroseconds.toDouble() / Duration.MICROSECONDS_PER_SECOND;
+    _value = _simulation.x(elapsedInSeconds);
+    if (_simulation.isDone(elapsedInSeconds))
       stop();
-    return _animation.start(simulation);
+    _onTick(_value);
   }
 }

packages/flutter/lib/src/animation/animated_simulation.dart → packages/flutter/lib/src/animation/ticker.dart

@@ -4,29 +4,27 @@
 
 import 'dart:async';
 
-import 'package:newton/newton.dart';
 import 'package:sky/src/animation/scheduler.dart';
 
-const double _kSecondsPerMillisecond = 1000.0;
-
-// TODO(abarth): Change from double to Duration.
-typedef _TickerCallback(double timeStamp);
+typedef TickerCallback(Duration elapsed);
 
 /// Calls its callback once per animation frame
 class Ticker {
   /// Constructs a ticker that will call onTick once per frame while running
-  Ticker(_TickerCallback onTick) : _onTick = onTick;
+  Ticker(TickerCallback onTick) : _onTick = onTick;
 
-  final _TickerCallback _onTick;
+  final TickerCallback _onTick;
 
   Completer _completer;
   int _animationId;
+  Duration _startTime;
 
   /// Start calling onTick once per animation frame
   ///
   /// The returned future resolves once the ticker stops ticking.
   Future start() {
     assert(!isTicking);
+    assert(_startTime == null);
     _completer = new Completer();
     _scheduleTick();
     return _completer.future;
@@ -39,12 +37,14 @@ class Ticker {
     if (!isTicking)
       return;
 
+    _startTime = null;
+
     if (_animationId != null) {
       scheduler.cancelAnimationFrame(_animationId);
       _animationId = null;
     }
 
-    // We take the _completer into a local variable so that !isTicking
+    // We take the _completer into a local variable so that isTicking is false
     // when we actually complete the future (isTicking uses _completer
     // to determine its state).
     Completer localCompleter = _completer;
@@ -56,12 +56,15 @@ class Ticker {
   /// Whether this ticker has scheduled a call to onTick
   bool get isTicking => _completer != null;
 
-  void _tick(double timeStamp) {
+  void _tick(Duration timeStamp) {
     assert(isTicking);
     assert(_animationId != null);
     _animationId = null;
 
-    _onTick(timeStamp);
+    if (_startTime == null)
+      _startTime = timeStamp;
+
+    _onTick(timeStamp - _startTime);
 
     // The onTick callback may have scheduled another tick already.
     if (isTicking && _animationId == null)
@@ -74,63 +77,3 @@ class Ticker {
     _animationId = scheduler.requestAnimationFrame(_tick);
   }
 }
-
-/// Ticks a simulation once per frame
-class AnimatedSimulation {
-
-  AnimatedSimulation(Function onTick) : _onTick = onTick {
-    _ticker = new Ticker(_tick);
-  }
-
-  final Function _onTick;
-  Ticker _ticker;
-
-  Simulation _simulation;
-  double _startTime;
-
-  double _value = 0.0;
-  /// The current value of the simulation
-  double get value => _value;
-  void set value(double newValue) {
-    assert(!_ticker.isTicking);
-    _value = newValue;
-    _onTick(_value);
-  }
-
-  /// Start ticking the given simulation once per frame
-  ///
-  /// Returns a future that resolves when the simulation stops ticking.
-  Future start(Simulation simulation) {
-    assert(simulation != null);
-    assert(!_ticker.isTicking);
-    _simulation = simulation;
-    _startTime = null;
-    _value = simulation.x(0.0);
-    return _ticker.start();
-  }
-
-  /// Stop ticking the current simulation
-  void stop() {
-    _simulation = null;
-    _startTime = null;
-    _ticker.stop();
-  }
-
-  /// Whether this object is currently ticking a simulation
-  bool get isAnimating => _ticker.isTicking;
-
-  void _tick(double timeStamp) {
-    if (_startTime == null)
-      _startTime = timeStamp;
-
-    double timeInSeconds = (timeStamp - _startTime) / _kSecondsPerMillisecond;
-    _value = _simulation.x(timeInSeconds);
-    final bool isLastTick = _simulation.isDone(timeInSeconds);
-
-    if (isLastTick)
-      stop();
-
-    _onTick(_value);
-  }
-
-}

packages/flutter/lib/src/gestures/long_press.dart

@@ -9,13 +9,13 @@ import 'package:sky/src/gestures/constants.dart';
 import 'package:sky/src/gestures/pointer_router.dart';
 import 'package:sky/src/gestures/recognizer.dart';
 
-typedef void GestureLongPressListener();
+typedef void GestureLongPressCallback();
 
 class LongPressGestureRecognizer extends PrimaryPointerGestureRecognizer {
   LongPressGestureRecognizer({ PointerRouter router, this.onLongPress })
     : super(router: router, deadline: kTapTimeout + kLongPressTimeout);
 
-  GestureLongPressListener onLongPress;
+  GestureLongPressCallback onLongPress;
 
   void didExceedDeadline() {
     resolve(GestureDisposition.accepted);

packages/flutter/lib/src/gestures/recognizer.dart

@@ -12,7 +12,9 @@ import 'package:sky/src/gestures/pointer_router.dart';
 export 'package:sky/src/gestures/pointer_router.dart' show PointerRouter;
 
 abstract class GestureRecognizer extends GestureArenaMember {
-  GestureRecognizer({ PointerRouter router }) : _router = router;
+  GestureRecognizer({ PointerRouter router }) : _router = router {
+    assert(_router != null);
+  }
 
   PointerRouter _router;
 

packages/flutter/lib/src/gestures/show_press.dart

@@ -8,13 +8,13 @@ import 'package:sky/src/gestures/arena.dart';
 import 'package:sky/src/gestures/constants.dart';
 import 'package:sky/src/gestures/recognizer.dart';
 
-typedef void GestureShowPressListener();
+typedef void GestureShowPressCallback();
 
 class ShowPressGestureRecognizer extends PrimaryPointerGestureRecognizer {
   ShowPressGestureRecognizer({ PointerRouter router, this.onShowPress })
     : super(router: router, deadline: kTapTimeout);
 
-  GestureShowPressListener onShowPress;
+  GestureShowPressCallback onShowPress;
 
   void didExceedDeadline() {
     // Show press isn't an exclusive gesture. We can recognize a show press

packages/flutter/lib/src/gestures/tap.dart

@@ -8,13 +8,15 @@ import 'package:sky/src/gestures/arena.dart';
 import 'package:sky/src/gestures/constants.dart';
 import 'package:sky/src/gestures/recognizer.dart';
 
-typedef void GestureTapListener();
+typedef void GestureTapCallback();
 
 class TapGestureRecognizer extends PrimaryPointerGestureRecognizer {
   TapGestureRecognizer({ PointerRouter router, this.onTap })
     : super(router: router, deadline: kTapTimeout);
 
-  GestureTapListener onTap;
+  GestureTapCallback onTap;
+  GestureTapCallback onTapDown;
+  GestureTapCallback onTapCancel;
 
   void didExceedDeadline() {
     stopTrackingPointer(primaryPointer);
@@ -22,9 +24,22 @@ class TapGestureRecognizer extends PrimaryPointerGestureRecognizer {
   }
 
   void handlePrimaryPointer(sky.PointerEvent event) {
-    if (event.type == 'pointerup') {
+    if (event.type == 'pointerdown') {
+      if (onTapDown != null)
+        onTapDown();
+    } else if (event.type == 'pointerup') {
       resolve(GestureDisposition.accepted);
+      if (onTap != null)
         onTap();
     }
   }
+
+  void rejectGesture(int pointer) {
+    super.rejectGesture(pointer);
+    if (pointer == primaryPointer) {
+      assert(state == GestureRecognizerState.defunct);
+      if (onTapCancel != null)
+        onTapCancel();
+    }
+  }
 }

packages/flutter/lib/src/painting/radial_reaction.dart

@@ -30,13 +30,13 @@ class RadialReaction {
     _outerOpacity = new AnimatedValue<double>(0.0, end: _kMaxOpacity, curve: easeOut);
     _innerCenter = new AnimatedValue<Point>(startPosition, end: center, curve: easeOut);
     _innerRadius = new AnimatedValue<double>(0.0, end: radius, curve: easeOut);
-    _showPerformance = new AnimationPerformance(duration: _kShowDuration)
+    _showPerformance = new Performance(duration: _kShowDuration)
       ..addListener(() {
         _showPerformance.updateVariable(_outerOpacity);
         _showPerformance.updateVariable(_innerCenter);
         _showPerformance.updateVariable(_innerRadius);
       });
-    _fade = new ValueAnimation<double>(
+    _fade = new ValuePerformance<double>(
       variable: new AnimatedValue(1.0, end: 0.0, curve: easeIn),
       duration: _kHideDuration
     );
@@ -48,14 +48,14 @@ class RadialReaction {
   /// The radius of the circle in which the reaction occurs
   final double radius;
 
-  AnimationPerformance _showPerformance;
+  Performance _showPerformance;
   AnimatedValue<double> _outerOpacity;
   AnimatedValue<Point> _innerCenter;
   AnimatedValue<double> _innerRadius;
 
   Future _showComplete;
 
-  ValueAnimation<double> _fade;
+  ValuePerformance<double> _fade;
 
   /// Show the reaction
   ///

packages/flutter/lib/src/rendering/binding.dart

@@ -78,7 +78,7 @@ class FlutterBinding extends HitTestTarget {
   }
 
   /// Pump the rendering pipeline to generate a frame for the given time stamp
-  void beginFrame(double timeStamp) {
+  void beginFrame(Duration timeStamp) {
     RenderObject.flushLayout();
     _renderView.updateCompositingBits();
     RenderObject.flushPaint();

packages/flutter/lib/src/rendering/box.dart

@@ -178,6 +178,60 @@ class BoxConstraints extends Constraints {
            (minHeight <= size.height) && (size.height <= math.max(minHeight, maxHeight));
   }
 
+  BoxConstraints operator*(double other) {
+    return new BoxConstraints(
+      minWidth: minWidth * other,
+      maxWidth: maxWidth * other,
+      minHeight: minHeight * other,
+      maxHeight: maxHeight * other
+    );
+  }
+
+  BoxConstraints operator/(double other) {
+    return new BoxConstraints(
+      minWidth: minWidth / other,
+      maxWidth: maxWidth / other,
+      minHeight: minHeight / other,
+      maxHeight: maxHeight / other
+    );
+  }
+
+  BoxConstraints operator~/(double other) {
+    return new BoxConstraints(
+      minWidth: (minWidth ~/ other).toDouble(),
+      maxWidth: (maxWidth ~/ other).toDouble(),
+      minHeight: (minHeight ~/ other).toDouble(),
+      maxHeight: (maxHeight ~/ other).toDouble()
+    );
+  }
+
+  BoxConstraints operator%(double other) {
+    return new BoxConstraints(
+      minWidth: minWidth % other,
+      maxWidth: maxWidth % other,
+      minHeight: minHeight % other,
+      maxHeight: maxHeight % other
+    );
+  }
+
+  /// Linearly interpolate between two BoxConstraints
+  ///
+  /// If either is null, this function interpolates from [BoxConstraints.zero].
+  static BoxConstraints lerp(BoxConstraints a, BoxConstraints b, double t) {
+    if (a == null && b == null)
+      return null;
+    if (a == null)
+      return b * t;
+    if (b == null)
+      return a * (1.0 - t);
+    return new BoxConstraints(
+      minWidth: sky.lerpDouble(a.minWidth, b.minWidth, t),
+      maxWidth: sky.lerpDouble(a.maxWidth, b.maxWidth, t),
+      minHeight: sky.lerpDouble(a.minHeight, b.minHeight, t),
+      maxHeight: sky.lerpDouble(a.maxHeight, b.maxHeight, t)
+    );
+  }
+
   bool operator ==(other) {
     if (identical(this, other))
       return true;

packages/flutter/lib/src/rendering/layer.dart

@@ -87,6 +87,29 @@ class PictureLayer extends Layer {
 
 }
 
+/// A layer that indicates to the compositor that it should display
+/// certain statistics within it
+class StatisticsLayer extends Layer {
+  StatisticsLayer({
+    Offset offset: Offset.zero,
+    this.paintBounds,
+    this.optionsMask
+  }) : super(offset: offset);
+
+  /// The rectangle in this layer's coodinate system that bounds the recording
+  Rect paintBounds;
+
+  /// A mask specifying the statistics to display
+  int optionsMask;
+
+  void addToScene(sky.SceneBuilder builder, Offset layerOffset) {
+    assert(optionsMask != null);
+    builder.addStatistics(optionsMask, paintBounds.shift(layerOffset));
+  }
+
+}
+
+
 /// A composited layer that has a list of children
 class ContainerLayer extends Layer {
   ContainerLayer({ Offset offset: Offset.zero }) : super(offset: offset);

packages/flutter/lib/src/rendering/object.dart

@@ -16,6 +16,8 @@ import 'package:vector_math/vector_math_64.dart';
 export 'dart:sky' show Point, Offset, Size, Rect, Color, Paint, Path;
 export 'package:sky/src/rendering/hit_test.dart' show HitTestTarget, HitTestEntry, HitTestResult;
 
+typedef sky.Shader ShaderCallback(Rect bounds);
+
 /// Base class for data associated with a [RenderObject] by its parent
 ///
 /// Some render objects wish to store data on their children, such as their
@@ -130,6 +132,15 @@ class PaintingContext {
     }
   }
 
+  void paintStatistics(int optionsMask, Offset offset, Size size) {
+    StatisticsLayer statsLayer = new StatisticsLayer(
+      offset: offset,
+      paintBounds: new Rect.fromLTWH(0.0, 0.0, size.width, size.height),
+      optionsMask : optionsMask
+    );
+    _containerLayer.append(statsLayer);
+  }
+
   // Below we have various variants of the paintChild() method, which
   // do additional work, such as clipping or transforming, at the same
   // time as painting the children.
@@ -300,6 +311,34 @@ class PaintingContext {
     }
   }
 
+  static Paint _getPaintForShaderMask(Rect bounds,
+                                      ShaderCallback shaderCallback,
+                                      sky.TransferMode transferMode) {
+    return new Paint()
+     ..transferMode = transferMode
+     ..shader = shaderCallback(bounds);
+  }
+
+  void paintChildWithShaderMask(RenderObject child,
+                                Point childPosition,
+                                Rect bounds,
+                                ShaderCallback shaderCallback,
+                                sky.TransferMode transferMode) {
+    assert(debugCanPaintChild(child));
+    final Offset childOffset = childPosition.toOffset();
+    if (!child.needsCompositing) {
+      canvas.saveLayer(bounds, new Paint());
+      canvas.translate(childOffset.dx, childOffset.dy);
+      insertChild(child, Offset.zero);
+      Paint shaderPaint = _getPaintForShaderMask(bounds, shaderCallback, transferMode);
+      canvas.drawRect(Offset.zero & new Size(bounds.width, bounds.height), shaderPaint);
+      canvas.restore();
+    } else {
+      // TODO(hansmuller) support compositing ShaderMasks
+      assert('Support for compositing ShaderMasks is TBD' is String);
+    }
+  }
+
   /// Instructs the child to draw itself onto this context at the given offset
   ///
   /// Do not call directly. This function is visible so that it can be

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -659,6 +659,37 @@ class RenderColorFilter extends RenderProxyBox {
   }
 }
 
+class RenderShaderMask extends RenderProxyBox {
+  RenderShaderMask({ RenderBox child, ShaderCallback shaderCallback, sky.TransferMode transferMode })
+    : _shaderCallback = shaderCallback, _transferMode = transferMode, super(child) {
+  }
+
+  ShaderCallback get shaderCallback => _shaderCallback;
+  ShaderCallback _shaderCallback;
+  void set shaderCallback (ShaderCallback newShaderCallback) {
+    assert(newShaderCallback != null);
+    if (_shaderCallback == newShaderCallback)
+      return;
+    _shaderCallback = newShaderCallback;
+    markNeedsPaint();
+  }
+
+  sky.TransferMode get transferMode => _transferMode;
+  sky.TransferMode _transferMode;
+  void set transferMode (sky.TransferMode newTransferMode) {
+    assert(newTransferMode != null);
+    if (_transferMode == newTransferMode)
+      return;
+    _transferMode = newTransferMode;
+    markNeedsPaint();
+  }
+
+  void paint(PaintingContext context, Offset offset) {
+    if (child != null)
+      context.paintChildWithShaderMask(child, offset.toPoint(), offset & size, _shaderCallback, _transferMode);
+  }
+}
+
 /// Clips its child using a rectangle
 ///
 /// Prevents its child from painting outside its bounds.

packages/flutter/lib/src/rendering/statistics_box.dart

+// 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 'package:sky/src/rendering/box.dart';
+import 'package:sky/src/rendering/object.dart';
+
+class StatisticsBox extends RenderBox {
+
+  StatisticsBox({int optionsMask: 0}) : _optionsMask = optionsMask;
+
+  int _optionsMask;
+  int get optionsMask => _optionsMask;
+  void set optionsMask (int mask) {
+    if (mask == _optionsMask) {
+      return;
+    }
+    _optionsMask = mask;
+    markNeedsPaint();
+  }
+
+  bool get sizedByParent => true;
+
+  double getMinIntrinsicWidth(BoxConstraints constraints) {
+    return constraints.minWidth;
+  }
+
+  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+    return constraints.maxWidth;
+  }
+
+  double getMinIntrinsicHeight(BoxConstraints constraints) {
+    return constraints.minHeight;
+  }
+
+  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+    return constraints.maxHeight;
+  }
+
+  void performResize() {
+    size = constraints.constrain(Size.infinite);
+  }
+
+  void paint(PaintingContext context, Offset offset) {
+    context.paintStatistics(optionsMask, offset, size);
+  }
+}

packages/flutter/lib/src/rendering/toggleable.dart

@@ -24,15 +24,15 @@ abstract class RenderToggleable extends RenderConstrainedBox {
       : _value = value,
         _onChanged = onChanged,
         super(additionalConstraints: new BoxConstraints.tight(size)) {
-    _performance = new ValueAnimation<double>(
+    _performance = new ValuePerformance<double>(
       variable: new AnimatedValue<double>(0.0, end: 1.0, curve: easeIn, reverseCurve: easeOut),
       duration: _kToggleDuration,
       progress: _value ? 1.0 : 0.0
     )..addListener(markNeedsPaint);
   }
 
-  ValueAnimation<double> get performance => _performance;
-  ValueAnimation<double> _performance;
+  ValuePerformance<double> get performance => _performance;
+  ValuePerformance<double> _performance;
 
   double get position => _performance.value;
 
@@ -51,7 +51,7 @@ abstract class RenderToggleable extends RenderConstrainedBox {
     );
   }
 
-  void detatch() {
+  void detach() {
     _tap.dispose();
     _tap = null;
     super.detach();
@@ -68,7 +68,7 @@ abstract class RenderToggleable extends RenderConstrainedBox {
     if (value == _value)
       return;
     _value = value;
-    performance.play(value ? Direction.forward : Direction.reverse);
+    performance.play(value ? AnimationDirection.forward : AnimationDirection.reverse);
   }
 
   ValueChanged get onChanged => _onChanged;

packages/flutter/lib/src/widgets/animated_component.dart

@@ -9,13 +9,13 @@ abstract class AnimatedComponent extends StatefulComponent {
   const AnimatedComponent({ Key key, this.direction, this.duration }) : super(key: key);
 
   final Duration duration;
-  final Direction direction;
+  final AnimationDirection direction;
 }
 
 abstract class AnimatedState<T extends AnimatedComponent> extends State<T> {
   void initState() {
     super.initState();
-    _performance = new AnimationPerformance(duration: config.duration);
+    _performance = new Performance(duration: config.duration);
     performance.addStatusListener(_handleAnimationStatusChanged);
     if (buildDependsOnPerformance) {
       performance.addListener(() {
@@ -34,13 +34,13 @@ abstract class AnimatedState<T extends AnimatedComponent> extends State<T> {
       performance.play(config.direction);
   }
 
-  AnimationPerformance get performance => _performance;
-  AnimationPerformance _performance;
+  Performance get performance => _performance;
+  Performance _performance;
 
-  void _handleAnimationStatusChanged(AnimationStatus status) {
-    if (status == AnimationStatus.completed)
+  void _handleAnimationStatusChanged(PerformanceStatus status) {
+    if (status == PerformanceStatus.completed)
       handleCompleted();
-    else if (status == AnimationStatus.dismissed)
+    else if (status == PerformanceStatus.dismissed)
       handleDismissed();
   }
 

packages/flutter/lib/src/widgets/animated_container.dart

+// 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 'package:sky/animation.dart';
+import 'package:sky/src/widgets/basic.dart';
+import 'package:sky/src/widgets/framework.dart';
+
+import 'package:vector_math/vector_math_64.dart';
+
+class AnimatedBoxConstraintsValue extends AnimatedValue<BoxConstraints> {
+  AnimatedBoxConstraintsValue(BoxConstraints begin, { BoxConstraints end, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
+
+  BoxConstraints lerp(double t) => BoxConstraints.lerp(begin, end, t);
+}
+
+class AnimatedBoxDecorationValue extends AnimatedValue<BoxDecoration> {
+  AnimatedBoxDecorationValue(BoxDecoration begin, { BoxDecoration end, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
+
+  BoxDecoration lerp(double t) => BoxDecoration.lerp(begin, end, t);
+}
+
+class AnimatedEdgeDimsValue extends AnimatedValue<EdgeDims> {
+  AnimatedEdgeDimsValue(EdgeDims begin, { EdgeDims end, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
+
+  EdgeDims lerp(double t) => EdgeDims.lerp(begin, end, t);
+}
+
+class AnimatedMatrix4Value extends AnimatedValue<Matrix4> {
+  AnimatedMatrix4Value(Matrix4 begin, { Matrix4 end, Curve curve, Curve reverseCurve })
+    : super(begin, end: end, curve: curve, reverseCurve: reverseCurve);
+
+  Matrix4 lerp(double t) {
+    // TODO(mpcomplete): Animate the full matrix. Will animating the cells
+    // separately work?
+    Vector3 beginT = begin.getTranslation();
+    Vector3 endT = end.getTranslation();
+    Vector3 lerpT = beginT*(1.0-t) + endT*t;
+    return new Matrix4.identity()..translate(lerpT);
+  }
+}
+
+class AnimatedContainer extends StatefulComponent {
+  AnimatedContainer({
+    Key key,
+    this.child,
+    this.constraints,
+    this.decoration,
+    this.foregroundDecoration,
+    this.margin,
+    this.padding,
+    this.transform,
+    this.width,
+    this.height,
+    this.curve: linear,
+    this.duration
+  }) : super(key: key) {
+    assert(margin == null || margin.isNonNegative);
+    assert(padding == null || padding.isNonNegative);
+    assert(curve != null);
+    assert(duration != null);
+  }
+
+  final Widget child;
+  final BoxConstraints constraints;
+  final BoxDecoration decoration;
+  final BoxDecoration foregroundDecoration;
+  final EdgeDims margin;
+  final EdgeDims padding;
+  final Matrix4 transform;
+  final double width;
+  final double height;
+
+  final Curve curve;
+  final Duration duration;
+
+  AnimatedContainerState createState() => new AnimatedContainerState();
+}
+
+class AnimatedContainerState extends State<AnimatedContainer> {
+  AnimatedBoxConstraintsValue _constraints;
+  AnimatedBoxDecorationValue _decoration;
+  AnimatedBoxDecorationValue _foregroundDecoration;
+  AnimatedEdgeDimsValue _margin;
+  AnimatedEdgeDimsValue _padding;
+  AnimatedMatrix4Value _transform;
+  AnimatedValue<double> _width;
+  AnimatedValue<double> _height;
+
+  Performance _performance;
+
+  void initState() {
+    super.initState();
+    _performance = new Performance(duration: config.duration)
+      ..timing = new AnimationTiming(curve: config.curve)
+      ..addListener(_updateAllVariables);
+    _configAllVariables();
+  }
+
+  void didUpdateConfig(AnimatedContainer oldConfig) {
+    _performance
+      ..duration = config.duration
+      ..timing.curve = config.curve;
+    if (_configAllVariables()) {
+      _performance.progress = 0.0;
+      _performance.play();
+    }
+  }
+
+  void dispose() {
+    _performance.stop();
+    super.dispose();
+  }
+
+  void _updateVariable(Animatable variable) {
+    if (variable != null)
+      _performance.updateVariable(variable);
+  }
+
+  void _updateAllVariables() {
+    setState(() {
+      _updateVariable(_constraints);
+      _updateVariable(_constraints);
+      _updateVariable(_decoration);
+      _updateVariable(_foregroundDecoration);
+      _updateVariable(_margin);
+      _updateVariable(_padding);
+      _updateVariable(_transform);
+      _updateVariable(_width);
+      _updateVariable(_height);
+    });
+  }
+
+  bool _configVariable(AnimatedValue variable, dynamic targetValue) {
+    dynamic currentValue = variable.value;
+    variable.end = targetValue;
+    variable.begin = currentValue;
+    return currentValue != targetValue;
+  }
+
+  bool _configAllVariables() {
+    bool needsAnimation = false;
+    if (config.constraints != null) {
+      _constraints ??= new AnimatedBoxConstraintsValue(config.constraints);
+      if (_configVariable(_constraints, config.constraints))
+        needsAnimation = true;
+    } else {
+      _constraints = null;
+    }
+
+    if (config.decoration != null) {
+      _decoration ??= new AnimatedBoxDecorationValue(config.decoration);
+      if (_configVariable(_decoration, config.decoration))
+        needsAnimation = true;
+    } else {
+      _decoration = null;
+    }
+
+    if (config.foregroundDecoration != null) {
+      _foregroundDecoration ??= new AnimatedBoxDecorationValue(config.foregroundDecoration);
+      if (_configVariable(_foregroundDecoration, config.foregroundDecoration))
+        needsAnimation = true;
+    } else {
+      _foregroundDecoration = null;
+    }
+
+    if (config.margin != null) {
+      _margin ??= new AnimatedEdgeDimsValue(config.margin);
+      if (_configVariable(_margin, config.margin))
+        needsAnimation = true;
+    } else {
+      _margin = null;
+    }
+
+    if (config.padding != null) {
+      _padding ??= new AnimatedEdgeDimsValue(config.padding);
+      if (_configVariable(_padding, config.padding))
+        needsAnimation = true;
+    } else {
+      _padding = null;
+    }
+
+    if (config.transform != null) {
+      _transform ??= new AnimatedMatrix4Value(config.transform);
+      if (_configVariable(_transform, config.transform))
+        needsAnimation = true;
+    } else {
+      _transform = null;
+    }
+
+    if (config.width != null) {
+      _width ??= new AnimatedValue<double>(config.width);
+      if (_configVariable(_width, config.width))
+        needsAnimation = true;
+    } else {
+      _width = null;
+    }
+
+    if (config.height != null) {
+      _height ??= new AnimatedValue<double>(config.height);
+      if (_configVariable(_height, config.height))
+        needsAnimation = true;
+    } else {
+      _height = null;
+    }
+
+    return needsAnimation;
+  }
+
+  Widget build(BuildContext context) {
+    return new Container(
+      child: config.child,
+      constraints: _constraints?.value,
+      decoration: _decoration?.value,
+      foregroundDecoration: _foregroundDecoration?.value,
+      margin: _margin?.value,
+      padding: _padding?.value,
+      transform: _transform?.value,
+      width: _width?.value,
+      height: _height?.value
+    );
+  }
+}

packages/flutter/lib/src/widgets/app.dart

@@ -32,7 +32,15 @@ class App extends StatefulComponent {
     this.theme,
     this.routes,
     this.onGenerateRoute
-  }): super(key: key);
+  }) : super(key: key) {
+    assert(() {
+      'The "routes" argument to App() is required.';
+      'This might be a sign that you have not upgraded to our new Widgets framework.';
+      'For more details see: https://groups.google.com/forum/#!topic/flutter-dev/hcX3OvLws9c';
+      '...or look at our examples: https://github.com/flutter/engine/tree/master/examples';
+      return routes != null;      
+    });
+  }
 
   final String title;
   final ThemeData theme;

packages/flutter/lib/src/widgets/basic.dart

@@ -22,6 +22,7 @@ export 'package:sky/rendering.dart' show
     FlexAlignItems,
     FlexDirection,
     FlexJustifyContent,
+    Matrix4,
     Offset,
     Paint,
     Path,
@@ -69,6 +70,33 @@ class ColorFilter extends OneChildRenderObjectWidget {
   }
 }
 
+class ShaderMask extends OneChildRenderObjectWidget {
+  ShaderMask({
+    Key key,
+    this.shaderCallback,
+    this.transferMode: sky.TransferMode.modulate,
+    Widget child
+  }) : super(key: key, child: child) {
+    assert(shaderCallback != null);
+    assert(transferMode != null);
+  }
+
+  final ShaderCallback shaderCallback;
+  final sky.TransferMode transferMode;
+
+  RenderShaderMask createRenderObject() {
+    return new RenderShaderMask(
+      shaderCallback: shaderCallback,
+      transferMode: transferMode
+    );
+  }
+
+  void updateRenderObject(RenderShaderMask renderObject, ShaderMask oldWidget) {
+    renderObject.shaderCallback = shaderCallback;
+    renderObject.transferMode = transferMode;
+  }
+}
+
 class DecoratedBox extends OneChildRenderObjectWidget {
   DecoratedBox({
     Key key,
@@ -392,11 +420,11 @@ class Container extends StatelessComponent {
     this.constraints,
     this.decoration,
     this.foregroundDecoration,
-    this.width,
-    this.height,
     this.margin,
     this.padding,
-    this.transform
+    this.transform,
+    this.width,
+    this.height
   }) : super(key: key) {
     assert(margin == null || margin.isNonNegative);
     assert(padding == null || padding.isNonNegative);
@@ -684,6 +712,11 @@ class DefaultTextStyle extends InheritedWidget {
   }
 
   bool updateShouldNotify(DefaultTextStyle old) => style != old.style;
+
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    '$style'.split('\n').forEach(description.add);
+  }
 }
 
 class Text extends StatelessComponent {
@@ -710,6 +743,13 @@ class Text extends StatelessComponent {
       text = new StyledTextSpan(combinedStyle, [text]);
     return new Paragraph(text: text);
   }
+
+  void debugFillDescription(List<String> description) {
+    super.debugFillDescription(description);
+    description.add('"$data"');
+    if (style != null)
+      '$style'.split('\n').forEach(description.add);
+  }
 }
 
 class Image extends LeafRenderObjectWidget {
@@ -882,7 +922,7 @@ class Listener extends OneChildRenderObjectWidget {
     this.onPointerMove,
     this.onPointerUp,
     this.onPointerCancel
-  }): super(key: key, child: child);
+  }) : super(key: key, child: child);
 
   final PointerEventListener onPointerDown;
   final PointerEventListener onPointerMove;

packages/flutter/lib/src/widgets/binding.dart

@@ -35,7 +35,7 @@ class WidgetFlutterBinding extends FlutterBinding {
     );
   }
 
-  void beginFrame(double timeStamp) {
+  void beginFrame(Duration timeStamp) {
     buildDirtyElements();
     super.beginFrame(timeStamp);
     Element.finalizeTree();

packages/flutter/lib/src/widgets/checkbox.dart

@@ -61,7 +61,7 @@ class _CheckboxWrapper extends LeafRenderObjectWidget {
     this.onChanged,
     this.uncheckedColor,
     this.accentColor
-  }): super(key: key) {
+  }) : super(key: key) {
     assert(uncheckedColor != null);
     assert(accentColor != null);
   }

packages/flutter/lib/src/widgets/date_picker.dart

@@ -375,13 +375,12 @@ class YearPickerState extends ScrollableWidgetListState<YearPicker> {
     for(int i = start; i < start + count; i++) {
       int year = config.firstDate.year + i;
       String label = year.toString();
-      Widget item = new GestureDetector(
+      Widget item = new InkWell(
         key: new Key(label),
         onTap: () {
           DateTime result = new DateTime(year, config.selectedDate.month, config.selectedDate.day);
           config.onChanged(result);
         },
-        child: new InkWell(
         child: new Container(
           height: config.itemExtent,
           decoration: year == config.selectedDate.year ? new BoxDecoration(
@@ -392,7 +391,6 @@ class YearPickerState extends ScrollableWidgetListState<YearPicker> {
             child: new Text(label, style: style)
           )
         )
-        )
       );
       items.add(item);
     }

packages/flutter/lib/src/widgets/dialog.dart

@@ -5,6 +5,7 @@
 import 'dart:async';
 
 import 'package:sky/animation.dart';
+import 'package:sky/gestures.dart';
 import 'package:sky/material.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/focus.dart';
@@ -30,7 +31,7 @@ class Dialog extends StatelessComponent {
     this.contentPadding,
     this.actions,
     this.onDismiss
-  }): super(key: key);
+  }) : super(key: key);
 
   /// The (optional) title of the dialog is displayed in a large font at the top
   /// of the dialog.
@@ -52,7 +53,7 @@ class Dialog extends StatelessComponent {
   final List<Widget> actions;
 
   /// An (optional) callback that is called when the dialog is dismissed.
-  final Function onDismiss;
+  final GestureTapCallback onDismiss;
 
   Color _getColor(BuildContext context) {
     switch (Theme.of(context).brightness) {
@@ -140,11 +141,11 @@ class DialogRoute extends Route {
 
   Duration get transitionDuration => _kTransitionDuration;
   bool get opaque => false;
-  Widget build(NavigatorState navigator, WatchableAnimationPerformance nextRoutePerformance) {
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance) {
     return new FadeTransition(
       performance: performance,
       opacity: new AnimatedValue<double>(0.0, end: 1.0, curve: easeOut),
-      child: builder(navigator, this)
+      child: builder(new RouteArguments(navigator: navigator, previousPerformance: this.performance, nextPerformance: nextRoutePerformance))
     );
   }
 
@@ -158,11 +159,11 @@ Future showDialog(NavigatorState navigator, DialogBuilder builder) {
   Completer completer = new Completer();
   navigator.push(new DialogRoute(
     completer: completer,
-    builder: (navigator, route) {
+    builder: (RouteArguments args) {
       return new Focus(
-        key: new GlobalObjectKey(route),
+        key: new GlobalObjectKey(completer),
         autofocus: true,
-        child: builder(navigator)
+        child: builder(args.navigator)
       );
     }
   ));

packages/flutter/lib/src/widgets/dismissable.dart

@@ -12,7 +12,7 @@ import 'package:sky/src/widgets/gesture_detector.dart';
 
 const Duration _kCardDismissFadeout = const Duration(milliseconds: 200);
 const Duration _kCardDismissResize = const Duration(milliseconds: 300);
-final Interval _kCardDismissResizeInterval = new Interval(0.4, 1.0);
+const Curve _kCardDismissResizeCurve = const Interval(0.4, 1.0, curve: ease);
 const double _kMinFlingVelocity = 700.0;
 const double _kMinFlingVelocityDelta = 400.0;
 const double _kFlingVelocityScale = 1.0 / 300.0;
@@ -50,15 +50,15 @@ class Dismissable extends StatefulComponent {
 class DismissableState extends State<Dismissable> {
   void initState() {
     super.initState();
-    _fadePerformance = new AnimationPerformance(duration: _kCardDismissFadeout);
-    _fadePerformance.addStatusListener((AnimationStatus status) {
-      if (status == AnimationStatus.completed)
+    _fadePerformance = new Performance(duration: _kCardDismissFadeout);
+    _fadePerformance.addStatusListener((PerformanceStatus status) {
+      if (status == PerformanceStatus.completed)
         _handleFadeCompleted();
     });
   }
 
-  AnimationPerformance _fadePerformance;
-  AnimationPerformance _resizePerformance;
+  Performance _fadePerformance;
+  Performance _resizePerformance;
 
   Size _size;
   double _dragExtent = 0.0;
@@ -97,16 +97,11 @@ class DismissableState extends State<Dismissable> {
     assert(_resizePerformance == null);
 
     setState(() {
-      _resizePerformance = new AnimationPerformance()
+      _resizePerformance = new Performance()
         ..duration = _kCardDismissResize
         ..addListener(_handleResizeProgressChanged);
       _resizePerformance.play();
     });
-    // Our squash curve (ease) does not return v=0.0 for t=0.0, so we
-    // technically resize on the first frame. To make sure this doesn't confuse
-    // any other widgets (like MixedViewport, which checks for this kind of
-    // thing), we report a resize straight away.
-    _maybeCallOnResized();
   }
 
   void _handleResizeProgressChanged() {
@@ -226,13 +221,12 @@ class DismissableState extends State<Dismissable> {
   Widget build(BuildContext context) {
     if (_resizePerformance != null) {
       // make sure you remove this widget once it's been dismissed!
-      assert(_resizePerformance.status == AnimationStatus.forward);
+      assert(_resizePerformance.status == PerformanceStatus.forward);
 
       AnimatedValue<double> squashAxisExtent = new AnimatedValue<double>(
         _directionIsYAxis ? _size.width : _size.height,
         end: 0.0,
-        curve: ease,
-        interval: _kCardDismissResizeInterval
+        curve: _kCardDismissResizeCurve
       );
 
       return new SquashTransition(

packages/flutter/lib/src/widgets/drag_target.dart

@@ -45,7 +45,7 @@ class Draggable extends StatefulComponent {
     this.feedback,
     this.feedbackOffset: Offset.zero,
     this.dragAnchor: DragAnchor.child
-  }): super(key: key) {
+  }) : super(key: key) {
     assert(navigator != null);
     assert(child != null);
     assert(feedback != null);
@@ -258,7 +258,7 @@ class DragRoute extends Route {
   bool get opaque => false;
   Duration get transitionDuration => const Duration();
 
-  Widget build(NavigatorState navigator, WatchableAnimationPerformance nextRoutePerformance) {
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance) {
     return new Positioned(
       left: _lastOffset.dx,
       top: _lastOffset.dy,

packages/flutter/lib/src/widgets/drawer.dart

@@ -2,17 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:async';
-
 import 'package:sky/animation.dart';
 import 'package:sky/material.dart';
+import 'package:sky/src/widgets/animated_container.dart';
 import 'package:sky/src/widgets/framework.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/gesture_detector.dart';
 import 'package:sky/src/widgets/navigator.dart';
-import 'package:sky/src/widgets/scrollable.dart';
 import 'package:sky/src/widgets/theme.dart';
 import 'package:sky/src/widgets/transitions.dart';
+import 'package:sky/src/widgets/focus.dart';
 
 // TODO(eseidel): Draw width should vary based on device size:
 // http://www.google.com/design/spec/layout/structure.html#structure-side-nav
@@ -35,22 +34,16 @@ const Duration _kThemeChangeDuration = const Duration(milliseconds: 200);
 const Point _kOpenPosition = Point.origin;
 const Point _kClosedPosition = const Point(-_kWidth, 0.0);
 
-typedef void DrawerDismissedCallback();
-
 class Drawer extends StatefulComponent {
   Drawer({
     Key key,
-    this.children,
-    this.showing: false,
-    this.level: 0,
-    this.onDismissed,
+    this.child,
+    this.level: 3,
     this.navigator
   }) : super(key: key);
 
-  final List<Widget> children;
-  final bool showing;
+  final Widget child;
   final int level;
-  final DrawerDismissedCallback onDismissed;
   final NavigatorState navigator;
 
   DrawerState createState() => new DrawerState();
@@ -59,57 +52,37 @@ class Drawer extends StatefulComponent {
 class DrawerState extends State<Drawer> {
   void initState() {
     super.initState();
-    _performance = new AnimationPerformance(duration: _kBaseSettleDuration);
-    _performance.addStatusListener((AnimationStatus status) {
-      if (status == AnimationStatus.dismissed)
-        _handleDismissed();
-    });
-    // Use a spring force for animating the drawer. We can't use curves for
-    // this because we need a linear curve in order to track the user's finger
-    // while dragging.
-    _performance.attachedForce = kDefaultSpringForce;
-    if (config.navigator != null) {
-      // TODO(ianh): This is crazy. We should convert drawer to use a pattern like openDialog().
-      // https://github.com/domokit/sky_engine/pull/1186
-      scheduleMicrotask(() {
-        config.navigator.pushState(this, (_) => _performance.reverse());
+    _performance = new Performance(duration: _kBaseSettleDuration)
+      ..addStatusListener((PerformanceStatus status) {
+        if (status == PerformanceStatus.dismissed)
+          config.navigator.pop();
       });
+    _open();
   }
-    _performance.play(_direction);
-  }
-
-  AnimationPerformance _performance;
 
-  Direction get _direction => config.showing ? Direction.forward : Direction.reverse;
-
-  void didUpdateConfig(Drawer oldConfig) {
-    if (config.showing != oldConfig.showing)
-      _performance.play(_direction);
-  }
+  Performance _performance;
 
   Widget build(BuildContext context) {
-    var mask = new GestureDetector(
+    Widget mask = new GestureDetector(
+      onTap: _close,
       child: new ColorTransition(
         performance: _performance.view,
-        color: new AnimatedColorValue(Colors.transparent, end: const Color(0x7F000000)),
+        color: new AnimatedColorValue(Colors.transparent, end: Colors.black54),
         child: new Container()
-      ),
-      onTap: () {
-        _performance.reverse();
-      }
+      )
     );
 
     Widget content = new SlideTransition(
       performance: _performance.view,
       position: new AnimatedValue<Point>(_kClosedPosition, end: _kOpenPosition),
-      // TODO(abarth): Use AnimatedContainer
-      child: new Container(
-        // behavior: implicitlyAnimate(const Duration(milliseconds: 200)),
+      child: new AnimatedContainer(
+        curve: ease,
+        duration: _kThemeChangeDuration,
         decoration: new BoxDecoration(
           backgroundColor: Theme.of(context).canvasColor,
           boxShadow: shadows[config.level]),
         width: _kWidth,
-        child: new Block(config.children)
+        child: config.child
       )
     );
 
@@ -117,33 +90,64 @@ class DrawerState extends State<Drawer> {
       onHorizontalDragStart: _performance.stop,
       onHorizontalDragUpdate: _handleDragUpdate,
       onHorizontalDragEnd: _handleDragEnd,
-      child: new Stack([ mask, content ])
+      child: new Stack([
+        mask,
+        new Positioned(
+          top: 0.0,
+          left: 0.0,
+          bottom: 0.0,
+          child: content
+        )
+      ])
     );
   }
 
-  void _handleDismissed() {
-    if (config.navigator != null &&
-        config.navigator.currentRoute is StateRoute &&
-        (config.navigator.currentRoute as StateRoute).owner == this) // TODO(ianh): remove cast once analyzer is cleverer
-      config.navigator.pop();
-    if (config.onDismissed != null)
-      config.onDismissed();
-  }
-
   bool get _isMostlyClosed => _performance.progress < 0.5;
 
-  void _settle() { _isMostlyClosed ? _performance.reverse() : _performance.play(); }
-
   void _handleDragUpdate(double delta) {
     _performance.progress += delta / _kWidth;
   }
 
+  void _open() {
+    _performance.fling(velocity: 1.0);
+  }
+
+  void _close() {
+    _performance.fling(velocity: -1.0);
+  }
+
   void _handleDragEnd(Offset velocity) {
     if (velocity.dx.abs() >= _kMinFlingVelocity) {
       _performance.fling(velocity: velocity.dx * _kFlingVelocityScale);
+    } else if (_isMostlyClosed) {
+      _close();
     } else {
-      _settle();
+      _open();
     }
   }
+}
+
+class DrawerRoute extends Route {
+  DrawerRoute({ this.child, this.level });
+
+  final Widget child;
+  final int level;
+
+  bool get opaque => false;
+
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance) {
+    return new Focus(
+      key: new GlobalObjectKey(this),
+      autofocus: true,
+      child: new Drawer(
+        child: child,
+        level: level,
+        navigator: navigator
+      )
+    );
+  }
+}
 
+void showDrawer({ NavigatorState navigator, Widget child, int level: 3 }) {
+  navigator.push(new DrawerRoute(child: child, level: level));
 }

packages/flutter/lib/src/widgets/drawer_item.dart

@@ -10,7 +10,6 @@ import 'package:sky/painting.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/button_state.dart';
 import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/gesture_detector.dart';
 import 'package:sky/src/widgets/icon.dart';
 import 'package:sky/src/widgets/ink_well.dart';
 import 'package:sky/src/widgets/theme.dart';
@@ -21,7 +20,7 @@ class DrawerItem extends StatefulComponent {
 
   final String icon;
   final Widget child;
-  final GestureTapListener onPressed;
+  final GestureTapCallback onPressed;
   final bool selected;
 
   DrawerItemState createState() => new DrawerItemState();
@@ -76,15 +75,13 @@ class DrawerItemState extends ButtonState<DrawerItem> {
       )
     );
 
-    return new GestureDetector(
-      onTap: config.onPressed,
-      child: new Container(
+    return new Container(
       height: 48.0,
       decoration: new BoxDecoration(backgroundColor: _getBackgroundColor(themeData)),
       child: new InkWell(
+        onTap: config.onPressed,
         child: new Row(flexChildren)
       )
-      )
     );
   }
 }

packages/flutter/lib/src/widgets/flat_button.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:sky/gestures.dart';
 import 'package:sky/material.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
@@ -13,7 +14,7 @@ class FlatButton extends MaterialButton {
     Key key,
     Widget child,
     bool enabled: true,
-    Function onPressed
+    GestureTapCallback onPressed
   }) : super(key: key,
              child: child,
              enabled: enabled,

packages/flutter/lib/src/widgets/floating_action_button.dart

@@ -6,7 +6,6 @@ import 'package:sky/gestures.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/button_state.dart';
 import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/gesture_detector.dart';
 import 'package:sky/src/widgets/icon.dart';
 import 'package:sky/src/widgets/ink_well.dart';
 import 'package:sky/src/widgets/material.dart';
@@ -26,7 +25,7 @@ class FloatingActionButton extends StatefulComponent {
 
   final Widget child;
   final Color backgroundColor;
-  final GestureTapListener onPressed;
+  final GestureTapCallback onPressed;
 
   FloatingActionButtonState createState() => new FloatingActionButtonState();
 }
@@ -46,12 +45,11 @@ class FloatingActionButtonState extends ButtonState<FloatingActionButton> {
       type: MaterialType.circle,
       level: highlight ? 3 : 2,
       child: new ClipOval(
-        child: new GestureDetector(
-          onTap: config.onPressed,
         child: new Container(
           width: _kSize,
           height: _kSize,
           child: new InkWell(
+            onTap: config.onPressed,
             child: new Center(
               child: new IconTheme(
                 data: new IconThemeData(color: iconThemeColor),
@@ -61,7 +59,6 @@ class FloatingActionButtonState extends ButtonState<FloatingActionButton> {
           )
         )
       )
-      )
     );
   }
 }

packages/flutter/lib/src/widgets/framework.dart

@@ -181,7 +181,16 @@ abstract class Widget {
   /// Inflates this configuration to a concrete instance.
   Element createElement();
 
-  String toString() => '$runtimeType';
+  String toString() {
+    final String name = key == null ? '$runtimeType' : '$runtimeType-$key';
+    final List<String> data = <String>[];
+    debugFillDescription(data);
+    if (data.isEmpty)
+      return 'name';
+    return 'name(${data.join("; ")})';
+   }
+
+  void debugFillDescription(List<String> description) { }
 }
 
 /// RenderObjectWidgets provide the configuration for [RenderObjectElement]s,
@@ -482,9 +491,11 @@ final _InactiveElements _inactiveElements = new _InactiveElements();
 typedef void ElementVisitor(Element element);
 
 abstract class BuildContext {
-  InheritedWidget inheritedWidgetOfType(Type targetType);
+  Widget get widget;
   RenderObject findRenderObject();
+  InheritedWidget inheritedWidgetOfType(Type targetType);
   void visitAncestorElements(bool visitor(Element element));
+  void visitChildElements(void visitor(Element element));
 }
 
 /// Elements are the instantiations of Widget configurations.
@@ -536,6 +547,13 @@ abstract class Element<T extends Widget> implements BuildContext {
   /// Calls the argument for each child. Must be overridden by subclasses that support having children.
   void visitChildren(ElementVisitor visitor) { }
 
+  /// Wrapper around visitChildren for BuildContext.
+  void visitChildElements(void visitor(Element element)) {
+    // don't allow visitChildElements() during build, since children aren't necessarily built yet
+    assert(BuildableElement._debugStateLockLevel == 0);
+    visitChildren(visitor);
+  }
+
   bool detachChild(Element child) => false;
 
   /// This method is the core of the system.
@@ -782,6 +800,8 @@ abstract class Element<T extends Widget> implements BuildContext {
       description.add('no depth');
     if (widget == null)
       description.add('no widget');
+    else
+      widget.debugFillDescription(description);
   }
 
   String toStringDeep([String prefixLineOne = '', String prefixOtherLines = '']) {
@@ -948,11 +968,11 @@ abstract class BuildableElement<T extends Widget> extends Element<T> {
 
 /// Instantiation of StatelessComponent widgets.
 class StatelessComponentElement<T extends StatelessComponent> extends BuildableElement<T> {
-  StatelessComponentElement(StatelessComponent widget) : super(widget) {
+  StatelessComponentElement(T widget) : super(widget) {
     _builder = widget.build;
   }
 
-  void update(StatelessComponent newWidget) {
+  void update(T newWidget) {
     super.update(newWidget);
     assert(widget == newWidget);
     _builder = widget.build;
@@ -962,10 +982,10 @@ class StatelessComponentElement<T extends StatelessComponent> extends BuildableE
 }
 
 /// Instantiation of StatefulComponent widgets.
-class StatefulComponentElement extends BuildableElement<StatefulComponent> {
-  StatefulComponentElement(StatefulComponent widget)
+class StatefulComponentElement<T extends StatefulComponent, U extends State<T>> extends BuildableElement<T> {
+  StatefulComponentElement(T widget)
     : _state = widget.createState(), super(widget) {
-    assert(_state._debugTypesAreRight(widget));
+    assert(_state._debugTypesAreRight(widget)); // can't use T and U, since normally we don't actually set those
     assert(_state._element == null);
     _state._element = this;
     assert(_builder == null);
@@ -988,10 +1008,10 @@ class StatefulComponentElement extends BuildableElement<StatefulComponent> {
     assert(() { _state._debugLifecycleState = _StateLifecycle.ready; return true; });
   }
 
-  State get state => _state;
-  State _state;
+  U get state => _state;
+  U _state;
 
-  void update(StatefulComponent newWidget) {
+  void update(T newWidget) {
     super.update(newWidget);
     assert(widget == newWidget);
     StatefulComponent oldConfig = _state._config;

packages/flutter/lib/src/widgets/gesture_detector.dart

@@ -15,6 +15,8 @@ class GestureDetector extends StatefulComponent {
     this.child,
     this.onTap,
     this.onDoubleTap,
+    this.onTapDown,
+    this.onTapCancel,
     this.onShowPress,
     this.onLongPress,
     this.onVerticalDragStart,
@@ -32,10 +34,14 @@ class GestureDetector extends StatefulComponent {
   }) : super(key: key);
 
   final Widget child;
-  final GestureTapListener onTap;
+
+  final GestureTapCallback onTap;
+  final GestureTapCallback onTapDown;
+  final GestureTapCallback onTapCancel;
   final GestureTapListener onDoubleTap;
-  final GestureShowPressListener onShowPress;
-  final GestureLongPressListener onLongPress;
+
+  final GestureShowPressCallback onShowPress;
+  final GestureLongPressCallback onLongPress;
 
   final GestureDragStartCallback onVerticalDragStart;
   final GestureDragUpdateCallback onVerticalDragUpdate;
@@ -57,69 +63,24 @@ class GestureDetector extends StatefulComponent {
 }
 
 class GestureDetectorState extends State<GestureDetector> {
-  void initState() {
-    super.initState();
-    didUpdateConfig(null);
-  }
-
   final PointerRouter _router = FlutterBinding.instance.pointerRouter;
 
   TapGestureRecognizer _tap;
-  TapGestureRecognizer _ensureTap() {
-    if (_tap == null)
-      _tap = new TapGestureRecognizer(router: _router);
-    return _tap;
-  }
-
   DoubleTapGestureRecognizer _doubleTap;
-  DoubleTapGestureRecognizer _ensureDoubleTap() {
-    if (_doubleTap == null)
-      _doubleTap = new DoubleTapGestureRecognizer(router: _router);
-    return _doubleTap;
-  }
-
   ShowPressGestureRecognizer _showPress;
-  ShowPressGestureRecognizer _ensureShowPress() {
-    if (_showPress == null)
-      _showPress = new ShowPressGestureRecognizer(router: _router);
-    return _showPress;
-  }
-
   LongPressGestureRecognizer _longPress;
-  LongPressGestureRecognizer _ensureLongPress() {
-    if (_longPress == null)
-      _longPress = new LongPressGestureRecognizer(router: _router);
-    return _longPress;
-  }
-
   VerticalDragGestureRecognizer _verticalDrag;
-  VerticalDragGestureRecognizer _ensureVerticalDrag() {
-    if (_verticalDrag == null)
-      _verticalDrag = new VerticalDragGestureRecognizer(router: _router);
-    return _verticalDrag;
-  }
-
   HorizontalDragGestureRecognizer _horizontalDrag;
-  HorizontalDragGestureRecognizer _ensureHorizontalDrag() {
-    if (_horizontalDrag == null)
-      _horizontalDrag = new HorizontalDragGestureRecognizer(router: _router);
-    return _horizontalDrag;
-  }
-
   PanGestureRecognizer _pan;
-  PanGestureRecognizer _ensurePan() {
-    assert(_scale == null);  // Scale is a superset of pan; just use scale
-    if (_pan == null)
-      _pan = new PanGestureRecognizer(router: _router);
-    return _pan;
+  ScaleGestureRecognizer _scale;
+
+  void initState() {
+    super.initState();
+    _syncAll();
   }
 
-  ScaleGestureRecognizer _scale;
-  ScaleGestureRecognizer _ensureScale() {
-    assert(_pan == null);  // Scale is a superset of pan; just use scale
-    if (_scale == null)
-      _scale = new ScaleGestureRecognizer(router: _router);
-    return _scale;
+  void didUpdateConfig(GestureDetector oldConfig) {
+    _syncAll();
   }
 
   void dispose() {
@@ -134,7 +95,7 @@ class GestureDetectorState extends State<GestureDetector> {
     super.dispose();
   }
 
-  void didUpdateConfig(GestureDetector oldConfig) {
+  void _syncAll() {
     _syncTap();
     _syncDoubleTap();
     _syncShowPress();
@@ -146,10 +107,15 @@ class GestureDetectorState extends State<GestureDetector> {
   }
 
   void _syncTap() {
-    if (config.onTap == null)
+    if (config.onTap == null && config.onTapDown == null && config.onTapCancel == null) {
       _tap = _ensureDisposed(_tap);
-    else
-      _ensureTap().onTap = config.onTap;
+    } else {
+      _tap ??= new TapGestureRecognizer(router: _router);
+      _tap
+        ..onTap = config.onTap
+        ..onTapDown = config.onTapDown
+        ..onTapCancel = config.onTapCancel;
+    }
   }
 
   void _syncDoubleTap() {
@@ -160,24 +126,29 @@ class GestureDetectorState extends State<GestureDetector> {
   }
 
   void _syncShowPress() {
-    if (config.onShowPress == null)
+    if (config.onShowPress == null) {
       _showPress = _ensureDisposed(_showPress);
-    else
-      _ensureShowPress().onShowPress = config.onShowPress;
+    } else {
+      _showPress ??= new ShowPressGestureRecognizer(router: _router);
+      _showPress.onShowPress = config.onShowPress;
+    }
   }
 
   void _syncLongPress() {
-    if (config.onLongPress == null)
+    if (config.onLongPress == null) {
       _longPress = _ensureDisposed(_longPress);
-    else
-      _ensureLongPress().onLongPress = config.onLongPress;
+    } else {
+      _longPress ??= new LongPressGestureRecognizer(router: _router);
+      _longPress.onLongPress = config.onLongPress;
+    }
   }
 
   void _syncVerticalDrag() {
     if (config.onVerticalDragStart == null && config.onVerticalDragUpdate == null && config.onVerticalDragEnd == null) {
       _verticalDrag = _ensureDisposed(_verticalDrag);
     } else {
-      _ensureVerticalDrag()
+      _verticalDrag ??= new VerticalDragGestureRecognizer(router: _router);
+      _verticalDrag
         ..onStart = config.onVerticalDragStart
         ..onUpdate = config.onVerticalDragUpdate
         ..onEnd = config.onVerticalDragEnd;
@@ -188,7 +159,8 @@ class GestureDetectorState extends State<GestureDetector> {
     if (config.onHorizontalDragStart == null && config.onHorizontalDragUpdate == null && config.onHorizontalDragEnd == null) {
       _horizontalDrag = _ensureDisposed(_horizontalDrag);
     } else {
-      _ensureHorizontalDrag()
+      _horizontalDrag ??= new HorizontalDragGestureRecognizer(router: _router);
+      _horizontalDrag
         ..onStart = config.onHorizontalDragStart
         ..onUpdate = config.onHorizontalDragUpdate
         ..onEnd = config.onHorizontalDragEnd;
@@ -199,7 +171,9 @@ class GestureDetectorState extends State<GestureDetector> {
     if (config.onPanStart == null && config.onPanUpdate == null && config.onPanEnd == null) {
       _pan = _ensureDisposed(_pan);
     } else {
-      _ensurePan()
+      assert(_scale == null);  // Scale is a superset of pan; just use scale
+      _pan ??= new PanGestureRecognizer(router: _router);
+      _pan
         ..onStart = config.onPanStart
         ..onUpdate = config.onPanUpdate
         ..onEnd = config.onPanEnd;
@@ -208,9 +182,11 @@ class GestureDetectorState extends State<GestureDetector> {
 
   void _syncScale() {
     if (config.onScaleStart == null && config.onScaleUpdate == null && config.onScaleEnd == null) {
-      _scale = _ensureDisposed(_pan);
+      _scale = _ensureDisposed(_scale);
     } else {
-      _ensureScale()
+      assert(_pan == null);  // Scale is a superset of pan; just use scale
+      _scale ??= new ScaleGestureRecognizer(router: _router);
+      _scale
         ..onStart = config.onScaleStart
         ..onUpdate = config.onScaleUpdate
         ..onEnd = config.onScaleEnd;

packages/flutter/lib/src/widgets/icon_button.dart

@@ -4,6 +4,7 @@
 
 import 'dart:sky' as sky;
 
+import 'package:sky/gestures.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/icon.dart';
 import 'package:sky/src/widgets/framework.dart';
@@ -13,8 +14,8 @@ class IconButton extends StatelessComponent {
   const IconButton({ Key key, this.icon, this.onPressed, this.color }) : super(key: key);
 
   final String icon;
-  final Function onPressed;
   final Color color;
+  final GestureTapCallback onPressed;
 
   Widget build(BuildContext context) {
     Widget child = new Icon(type: icon, size: 24);

packages/flutter/lib/src/widgets/ink_well.dart

@@ -2,16 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:async';
 import 'dart:math' as math;
 import 'dart:sky' as sky;
 
 import 'package:sky/animation.dart';
+import 'package:sky/gestures.dart';
 import 'package:sky/rendering.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
 
 const int _kSplashInitialOpacity = 0x30;
-const double _kSplashCancelledVelocity = 0.7;
+const double _kSplashCanceledVelocity = 0.7;
 const double _kSplashConfirmedVelocity = 0.7;
 const double _kSplashInitialSize = 0.0;
 const double _kSplashUnconfirmedVelocity = 0.2;
@@ -25,40 +27,60 @@ double _getSplashTargetSize(Size bounds, Point position) {
 }
 
 class InkSplash {
-  InkSplash(this.pointer, this.position, this.well) {
+  InkSplash(this.position, this.well) {
     _targetRadius = _getSplashTargetSize(well.size, position);
     _radius = new AnimatedValue<double>(
         _kSplashInitialSize, end: _targetRadius, curve: easeOut);
 
-    _performance = new ValueAnimation<double>(
+    _performance = new ValuePerformance<double>(
       variable: _radius,
       duration: new Duration(milliseconds: (_targetRadius / _kSplashUnconfirmedVelocity).floor())
-    )..addListener(_handleRadiusChange)
-     ..play();
+    )..addListener(_handleRadiusChange);
+
+    // Wait kTapTimeout to avoid creating tiny splashes during scrolls.
+    _startTimer = new Timer(kTapTimeout, _play);
   }
 
-  final int pointer;
   final Point position;
   final RenderInkWell well;
 
   double _targetRadius;
   double _pinnedRadius;
   AnimatedValue<double> _radius;
-  AnimationPerformance _performance;
+  Performance _performance;
+  Timer _startTimer;
+
+  bool _cancelStartTimer() {
+    if (_startTimer != null) {
+      _startTimer.cancel();
+      _startTimer = null;
+      return true;
+    }
+    return false;
+  }
+
+  void _play() {
+    _cancelStartTimer();
+    _performance.play();
+  }
 
   void _updateVelocity(double velocity) {
     int duration = (_targetRadius / velocity).floor();
-    _performance
-      ..duration = new Duration(milliseconds: duration)
-      ..play();
+    _performance.duration = new Duration(milliseconds: duration);
+    _play();
   }
 
   void confirm() {
+    if (_cancelStartTimer())
+      return;
     _updateVelocity(_kSplashConfirmedVelocity);
+    _pinnedRadius = null;
   }
 
   void cancel() {
-    _updateVelocity(_kSplashCancelledVelocity);
+    if (_cancelStartTimer())
+      return;
+    _updateVelocity(_kSplashCanceledVelocity);
     _pinnedRadius = _radius.value;
   }
 
@@ -77,38 +99,95 @@ class InkSplash {
 }
 
 class RenderInkWell extends RenderProxyBox {
-  RenderInkWell({ RenderBox child }) : super(child);
+  RenderInkWell({
+    RenderBox child,
+    GestureTapCallback onTap,
+    GestureLongPressCallback onLongPress
+  }) : super(child) {
+    this.onTap = onTap;
+    this.onLongPress = onLongPress;
+  }
+
+  GestureTapCallback get onTap => _onTap;
+  GestureTapCallback _onTap;
+  void set onTap (GestureTapCallback value) {
+    _onTap = value;
+    _syncTapRecognizer();
+  }
+
+  GestureTapCallback get onLongPress => _onLongPress;
+  GestureTapCallback _onLongPress;
+  void set onLongPress (GestureTapCallback value) {
+    _onLongPress = value;
+    _syncLongPressRecognizer();
+  }
 
   final List<InkSplash> _splashes = new List<InkSplash>();
 
+  TapGestureRecognizer _tap;
+  LongPressGestureRecognizer _longPress;
+
   void handleEvent(sky.Event event, BoxHitTestEntry entry) {
-    // TODO(abarth): We should trigger these effects based on gestures.
-    // https://github.com/flutter/engine/issues/1271
-    if (event is sky.PointerEvent) {
-      switch (event.type) {
-        case 'pointerdown':
-          _startSplash(event.pointer, entry.localPosition);
-          break;
-        case 'pointerup':
-          _confirmSplash(event.pointer);
-          break;
+    if (event.type == 'pointerdown' && (_tap != null || _longPress != null)) {
+      _tap?.addPointer(event);
+      _longPress?.addPointer(event);
+      _splashes.add(new InkSplash(entry.localPosition, this));
+    }
+  }
+
+  void attach() {
+    super.attach();
+    _syncTapRecognizer();
+    _syncLongPressRecognizer();
+  }
+
+  void detach() {
+    _disposeTapRecognizer();
+    _disposeLongPressRecognizer();
+    super.detach();
+  }
+
+  void _syncTapRecognizer() {
+    if (onTap == null) {
+      _disposeTapRecognizer();
+    } else {
+      _tap ??= new TapGestureRecognizer(router: FlutterBinding.instance.pointerRouter)
+        ..onTap = _handleTap
+        ..onTapCancel = _handleTapCancel;
+    }
+  }
+
+  void _disposeTapRecognizer() {
+    _tap?.dispose();
+    _tap = null;
+  }
+
+  void _syncLongPressRecognizer() {
+    if (onLongPress == null) {
+      _disposeLongPressRecognizer();
+    } else {
+      _longPress ??= new LongPressGestureRecognizer(router: FlutterBinding.instance.pointerRouter)
+        ..onLongPress = _handleLongPress;
     }
   }
+
+  void _disposeLongPressRecognizer() {
+    _longPress?.dispose();
+    _longPress = null;
   }
 
-  void _startSplash(int pointer, Point position) {
-    _splashes.add(new InkSplash(pointer, position, this));
-    markNeedsPaint();
+  void _handleTap() {
+    _splashes.last?.confirm();
+    onTap();
   }
 
-  void _forEachSplash(int pointer, Function callback) {
-    _splashes.where((splash) => splash.pointer == pointer)
-             .forEach(callback);
+  void _handleTapCancel() {
+    _splashes.last?.cancel();
   }
 
-  void _confirmSplash(int pointer) {
-    _forEachSplash(pointer, (splash) { splash.confirm(); });
-    markNeedsPaint();
+  void _handleLongPress() {
+    _splashes.last?.confirm();
+    onLongPress();
   }
 
   void paint(PaintingContext context, Offset offset) {
@@ -126,6 +205,20 @@ class RenderInkWell extends RenderProxyBox {
 }
 
 class InkWell extends OneChildRenderObjectWidget {
-  InkWell({ Key key, Widget child }) : super(key: key, child: child);
-  RenderInkWell createRenderObject() => new RenderInkWell();
+  InkWell({
+    Key key,
+    Widget child,
+    this.onTap,
+    this.onLongPress
+  }) : super(key: key, child: child);
+
+  final GestureTapCallback onTap;
+  final GestureLongPressCallback onLongPress;
+
+  RenderInkWell createRenderObject() => new RenderInkWell(onTap: onTap, onLongPress: onLongPress);
+
+  void updateRenderObject(RenderInkWell renderObject, InkWell oldWidget) {
+    renderObject.onTap = onTap;
+    renderObject.onLongPress = onLongPress;
+  }
 }

packages/flutter/lib/src/widgets/input.dart

@@ -28,7 +28,7 @@ class Input extends Scrollable {
     this.placeholder,
     this.onChanged,
     this.keyboardType: KeyboardType.TEXT
-  }): super(
+  }) : super(
     key: key,
     initialScrollOffset: 0.0,
     scrollDirection: ScrollDirection.horizontal

packages/flutter/lib/src/widgets/material.dart

@@ -2,8 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:sky/animation.dart';
 import 'package:sky/painting.dart';
 import 'package:sky/material.dart';
+import 'package:sky/src/widgets/animated_container.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
 import 'package:sky/src/widgets/theme.dart';
@@ -61,10 +63,11 @@ class Material extends StatelessComponent {
         );
       }
     }
-    // TODO(abarth): This should use AnimatedContainer.
     return new DefaultTextStyle(
       style: Theme.of(context).text.body1,
-      child: new Container(
+      child: new AnimatedContainer(
+        curve: ease,
+        duration: const Duration(milliseconds: 200),
         decoration: new BoxDecoration(
           backgroundColor: getBackgroundColor(context),
           borderRadius: edges[type],

packages/flutter/lib/src/widgets/material_button.dart

@@ -2,10 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:sky/gestures.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/button_state.dart';
 import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/gesture_detector.dart';
 import 'package:sky/src/widgets/ink_well.dart';
 import 'package:sky/src/widgets/material.dart';
 
@@ -22,7 +22,7 @@ abstract class MaterialButton extends StatefulComponent {
 
   final Widget child;
   final bool enabled;
-  final Function onPressed;
+  final GestureTapCallback onPressed;
 }
 
 abstract class MaterialButtonState<T extends MaterialButton> extends ButtonState<T> {
@@ -37,17 +37,17 @@ abstract class MaterialButtonState<T extends MaterialButton> extends ButtonState
         child: config.child // TODO(ianh): figure out a way to compell the child to have gray text when disabled...
       )
     );
-    return new GestureDetector(
-      onTap: config.enabled ? config.onPressed : null,
-      child: new Container(
+    return new Container(
       height: 36.0,
       constraints: new BoxConstraints(minWidth: 88.0),
       margin: new EdgeDims.all(8.0),
       child: new Material(
         type: MaterialType.button,
-          child: config.enabled ? new InkWell(child: contents) : contents,
         level: level,
-          color: getColor(context)
+        color: getColor(context),
+        child: new InkWell(
+          onTap: config.enabled ? config.onPressed : null,
+          child: contents
         )
       )
     );

packages/flutter/lib/src/widgets/mixed_viewport.dart

@@ -22,7 +22,7 @@ class MixedViewport extends RenderObjectWidget {
     this.token,
     this.onExtentsUpdate,
     this.onInvalidatorAvailable
-  }): super(key: key);
+  }) : super(key: key);
 
   final double startOffset;
   final ScrollDirection direction;

packages/flutter/lib/src/widgets/navigator.dart

@@ -8,7 +8,14 @@ import 'package:sky/src/widgets/focus.dart';
 import 'package:sky/src/widgets/framework.dart';
 import 'package:sky/src/widgets/transitions.dart';
 
-typedef Widget RouteBuilder(NavigatorState navigator, Route route);
+class RouteArguments {
+  const RouteArguments({ this.navigator, this.previousPerformance, this.nextPerformance });
+  final NavigatorState navigator;
+  final PerformanceView previousPerformance;
+  final PerformanceView nextPerformance;
+}
+
+typedef Widget RouteBuilder(RouteArguments args);
 typedef RouteBuilder RouteGenerator(String name);
 typedef void StateRouteCallback(StateRoute route);
 typedef void NotificationCallback();
@@ -118,7 +125,7 @@ class NavigatorState extends State<Navigator> {
   Widget build(BuildContext context) {
     List<Widget> visibleRoutes = new List<Widget>();
     bool alreadyInsertModalBarrier = false;
-    WatchableAnimationPerformance nextPerformance;
+    PerformanceView nextPerformance;
     for (int i = _history.length-1; i >= 0; i -= 1) {
       Route route = _history[i];
       if (!route.hasContent) {
@@ -126,11 +133,16 @@ class NavigatorState extends State<Navigator> {
         continue;
       }
       route.ensurePerformance(
-        direction: (i <= _currentPosition) ? Direction.forward : Direction.reverse
+        direction: (i <= _currentPosition) ? AnimationDirection.forward : AnimationDirection.reverse
       );
       route._onDismissed = () {
-        setState(() {
         assert(_history.contains(route));
+        if (_history.lastIndexOf(route) <= _currentPosition)
+          popRoute(route);
+      };
+      route._onRemoveRoute = () {
+        assert(_history.contains(route));
+        setState(() {
           _history.remove(route);
         });
       };
@@ -154,33 +166,39 @@ class NavigatorState extends State<Navigator> {
     }
     return new Focus(child: new Stack(visibleRoutes.reversed.toList()));
   }
+
 }
 
 
 abstract class Route {
 
-  WatchableAnimationPerformance get performance => _performance?.view;
-  AnimationPerformance _performance;
+  PerformanceView get performance => _performance?.view;
+  Performance _performance;
   NotificationCallback _onDismissed;
+  NotificationCallback _onRemoveRoute;
 
-  AnimationPerformance createPerformance() {
+  Performance createPerformance() {
     Duration duration = transitionDuration;
     if (duration > Duration.ZERO) {
-      return new AnimationPerformance(duration: duration)
-        ..addStatusListener((AnimationStatus status) {
-          if (status == AnimationStatus.dismissed && _onDismissed != null)
+      return new Performance(duration: duration)
+        ..addStatusListener((PerformanceStatus status) {
+          if (status == PerformanceStatus.dismissed) {
+            if (_onDismissed != null)
               _onDismissed();
+            if (_onRemoveRoute != null)
+              _onRemoveRoute();
+          }
         });
     }
     return null;
   }
 
-  void ensurePerformance({ Direction direction }) {
+  void ensurePerformance({ AnimationDirection direction }) {
     assert(direction != null);
     if (_performance == null)
       _performance = createPerformance();
     if (_performance != null) {
-      AnimationStatus desiredStatus = direction == Direction.forward ? AnimationStatus.forward : AnimationStatus.reverse;
+      PerformanceStatus desiredStatus = direction == AnimationDirection.forward ? PerformanceStatus.forward : PerformanceStatus.reverse;
       if (_performance.status != desiredStatus)
         _performance.play(direction);
     }
@@ -236,17 +254,17 @@ abstract class Route {
   /// cover the entire application surface or are in any way semi-transparent.
   bool get opaque => false;
 
-  /// If this is set to a non-zero [Duration], then an [AnimationPerformance]
+  /// If this is set to a non-zero [Duration], then an [Performance]
   /// object, available via the performance field, will be created when the
   /// route is first built, using the duration described here.
   Duration get transitionDuration => Duration.ZERO;
 
   bool get isActuallyOpaque => (performance == null || _performance.isCompleted) && opaque;
 
-  Widget build(NavigatorState navigator, WatchableAnimationPerformance nextRoutePerformance);
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance);
   void didPop([dynamic result]) {
-    if (performance == null && _onDismissed != null)
-      _onDismissed();
+    if (performance == null && _onRemoveRoute != null)
+      _onRemoveRoute();
   }
 
   String toString() => '$runtimeType()';
@@ -263,7 +281,7 @@ class PageRoute extends Route {
   bool get opaque => true;
   Duration get transitionDuration => _kTransitionDuration;
 
-  Widget build(NavigatorState navigator, WatchableAnimationPerformance nextRoutePerformance) {
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance) {
     // TODO(jackson): Hit testing should ignore transform
     // TODO(jackson): Block input unless content is interactive
     return new SlideTransition(
@@ -272,7 +290,7 @@ class PageRoute extends Route {
       child: new FadeTransition(
         performance: performance,
         opacity: new AnimatedValue<double>(0.0, end: 1.0, curve: easeOut),
-        child: builder(navigator, this)
+        child: builder(new RouteArguments(navigator: navigator, previousPerformance: this.performance, nextPerformance: nextRoutePerformance))
       )
     );
   }
@@ -296,5 +314,5 @@ class StateRoute extends Route {
     super.didPop(result);
   }
 
-  Widget build(NavigatorState navigator, WatchableAnimationPerformance nextRoutePerformance) => null;
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance) => null;
 }

packages/flutter/lib/src/widgets/popup_menu.dart

@@ -11,7 +11,7 @@ import 'package:sky/painting.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/focus.dart';
 import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/gesture_detector.dart';
+import 'package:sky/src/widgets/ink_well.dart';
 import 'package:sky/src/widgets/navigator.dart';
 import 'package:sky/src/widgets/popup_menu_item.dart';
 import 'package:sky/src/widgets/scrollable.dart';
@@ -29,7 +29,7 @@ const double _kMenuVerticalPadding = 8.0;
 
 typedef List<PopupMenuItem> PopupMenuItemsBuilder(NavigatorState navigator);
 
-class PopupMenu extends StatefulComponent {
+class PopupMenu extends StatelessComponent {
   PopupMenu({
     Key key,
     this.items,
@@ -44,78 +44,48 @@ class PopupMenu extends StatefulComponent {
   final List<PopupMenuItem> items;
   final int level;
   final NavigatorState navigator;
-  final WatchableAnimationPerformance performance;
-
-  PopupMenuState createState() => new PopupMenuState();
-}
-
-class PopupMenuState extends State<PopupMenu> {
-  void initState() {
-    super.initState();
-    config.performance.addListener(_performanceChanged);
-  }
-
-  void didUpdateConfig(PopupMenu oldConfig) {
-    if (config.performance != oldConfig.performance) {
-      oldConfig.performance.removeListener(_performanceChanged);
-      config.performance.addListener(_performanceChanged);
-    }
-  }
-
-  void dispose() {
-    config.performance.removeListener(_performanceChanged);
-    super.dispose();
-  }
-
-  void _performanceChanged() {
-    setState(() {
-      // the performance changed, and our state is tied up with the performance
-    });
-  }
-
-  BoxPainter _painter;
-
-  void _updateBoxPainter(BoxDecoration decoration) {
-    if (_painter == null || _painter.decoration != decoration)
-      _painter = new BoxPainter(decoration);
-  }
+  final PerformanceView performance;
 
   Widget build(BuildContext context) {
-    _updateBoxPainter(new BoxDecoration(
+    final BoxPainter painter = new BoxPainter(new BoxDecoration(
       backgroundColor: Theme.of(context).canvasColor,
       borderRadius: 2.0,
-      boxShadow: shadows[config.level]
+      boxShadow: shadows[level]
     ));
-    double unit = 1.0 / (config.items.length + 1.5); // 1.0 for the width and 0.5 for the last item's fade.
+
+    double unit = 1.0 / (items.length + 1.5); // 1.0 for the width and 0.5 for the last item's fade.
     List<Widget> children = [];
-    for (int i = 0; i < config.items.length; ++i) {
+
+    for (int i = 0; i < items.length; ++i) {
       double start = (i + 1) * unit;
       double end = (start + 1.5 * unit).clamp(0.0, 1.0);
       children.add(new FadeTransition(
-        performance: config.performance,
-        opacity: new AnimatedValue<double>(0.0, end: 1.0, interval: new Interval(start, end)),
-        child: new GestureDetector(
-          onTap: () { config.navigator.pop(config.items[i].value); },
-          child: config.items[i]
+        performance: performance,
+        opacity: new AnimatedValue<double>(0.0, end: 1.0, curve: new Interval(start, end)),
+        child: new InkWell(
+          onTap: () { navigator.pop(items[i].value); },
+          child: items[i]
         ))
       );
     }
-    final width = new AnimatedValue<double>(0.0, end: 1.0, interval: new Interval(0.0, unit));
-    final height = new AnimatedValue<double>(0.0, end: 1.0, interval: new Interval(0.0, unit * config.items.length));
+
+    final width = new AnimatedValue<double>(0.0, end: 1.0, curve: new Interval(0.0, unit));
+    final height = new AnimatedValue<double>(0.0, end: 1.0, curve: new Interval(0.0, unit * items.length));
+
     return new FadeTransition(
-      performance: config.performance,
-      opacity: new AnimatedValue<double>(0.0, end: 1.0, interval: new Interval(0.0, 1.0 / 3.0)),
+      performance: performance,
+      opacity: new AnimatedValue<double>(0.0, end: 1.0, curve: new Interval(0.0, 1.0 / 3.0)),
       child: new Container(
         margin: new EdgeDims.all(_kMenuMargin),
         child: new BuilderTransition(
-          performance: config.performance,
+          performance: performance,
           variables: [width, height],
           builder: (BuildContext context) {
             return new CustomPaint(
               callback: (sky.Canvas canvas, Size size) {
                 double widthValue = width.value * size.width;
                 double heightValue = height.value * size.height;
-                _painter.paint(canvas, new Rect.fromLTWH(size.width - widthValue, 0.0, widthValue, heightValue));
+                painter.paint(canvas, new Rect.fromLTWH(size.width - widthValue, 0.0, widthValue, heightValue));
               },
               child: new ConstrainedBox(
                 constraints: new BoxConstraints(
@@ -159,10 +129,10 @@ class MenuRoute extends Route {
   final PopupMenuItemsBuilder builder;
   final int level;
 
-  AnimationPerformance createPerformance() {
-    AnimationPerformance result = super.createPerformance();
+  Performance createPerformance() {
+    Performance result = super.createPerformance();
     AnimationTiming timing = new AnimationTiming();
-    timing.reverseInterval = new Interval(0.0, _kMenuCloseIntervalEnd);
+    timing.reverseCurve = new Interval(0.0, _kMenuCloseIntervalEnd);
     result.timing = timing;
     return result;
   }
@@ -172,7 +142,7 @@ class MenuRoute extends Route {
   bool get opaque => false;
   Duration get transitionDuration => _kMenuDuration;
 
-  Widget build(NavigatorState navigator, WatchableAnimationPerformance nextRoutePerformance) {
+  Widget build(NavigatorState navigator, PerformanceView nextRoutePerformance) {
     return new Positioned(
       top: position?.top,
       right: position?.right,

packages/flutter/lib/src/widgets/popup_menu_item.dart

@@ -4,7 +4,6 @@
 
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/ink_well.dart';
 import 'package:sky/src/widgets/theme.dart';
 
 const double _kMenuItemHeight = 48.0;
@@ -21,8 +20,7 @@ class PopupMenuItem extends StatelessComponent {
   final dynamic value;
 
   Widget build(BuildContext context) {
-    return new InkWell(
-      child: new Container(
+    return new Container(
       height: _kMenuItemHeight,
       child: new DefaultTextStyle(
         style: Theme.of(context).text.subhead,
@@ -31,7 +29,6 @@ class PopupMenuItem extends StatelessComponent {
           child: child
         )
       )
-      )
     );
   }
 }

packages/flutter/lib/src/widgets/progress_indicator.dart

@@ -36,16 +36,16 @@ abstract class ProgressIndicator extends StatefulComponent {
 
 class ProgressIndicatorState extends State<ProgressIndicator> {
 
-  ValueAnimation<double> _performance;
+  ValuePerformance<double> _performance;
 
   void initState() {
     super.initState();
-    _performance = new ValueAnimation<double>(
+    _performance = new ValuePerformance<double>(
       variable: new AnimatedValue<double>(0.0, end: 1.0, curve: ease),
       duration: const Duration(milliseconds: 1500)
     );
-    _performance.addStatusListener((AnimationStatus status) {
-      if (status == AnimationStatus.completed)
+    _performance.addStatusListener((PerformanceStatus status) {
+      if (status == PerformanceStatus.completed)
         _restartAnimation();
     });
     _performance.play();

packages/flutter/lib/src/widgets/raised_button.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:sky/gestures.dart';
 import 'package:sky/material.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
@@ -13,7 +14,7 @@ class RaisedButton extends MaterialButton {
     Key key,
     Widget child,
     bool enabled: true,
-    Function onPressed
+    GestureTapCallback onPressed
   }) : super(key: key,
              child: child,
              enabled: enabled,

packages/flutter/lib/src/widgets/scrollable.dart

@@ -51,16 +51,10 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
     super.initState();
     if (config.initialScrollOffset is double)
       _scrollOffset = config.initialScrollOffset;
-    _toEndAnimation = new AnimatedSimulation(_setScrollOffset);
-    _toOffsetAnimation = new ValueAnimation<double>()
-      ..addListener(() {
-        AnimatedValue<double> offset = _toOffsetAnimation.variable;
-        _setScrollOffset(offset.value);
-      });
+    _animation = new SimulationStepper(_setScrollOffset);
   }
 
-  AnimatedSimulation _toEndAnimation; // See _startToEndAnimation()
-  ValueAnimation<double> _toOffsetAnimation; // Started by scrollTo()
+  SimulationStepper _animation;
 
   double _scrollOffset = 0.0;
   double get scrollOffset => _scrollOffset;
@@ -106,23 +100,10 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
 
   Widget buildContent(BuildContext context);
 
-  Future _startToOffsetAnimation(double newScrollOffset, Duration duration, Curve curve) {
-    _stopAnimations();
-    _toOffsetAnimation
-      ..variable = new AnimatedValue<double>(scrollOffset,
-        end: newScrollOffset,
-        curve: curve
-      )
-      ..progress = 0.0
-      ..duration = duration;
-    return _toOffsetAnimation.play();
-  }
-
-  void _stopAnimations() {
-    if (_toOffsetAnimation.isAnimating)
-      _toOffsetAnimation.stop();
-    if (_toEndAnimation.isAnimating)
-      _toEndAnimation.stop();
+  Future _animateTo(double newScrollOffset, Duration duration, Curve curve) {
+    _animation.stop();
+    _animation.value = scrollOffset;
+    return _animation.animateTo(newScrollOffset, duration: duration, curve: curve);
   }
 
   bool _scrollOffsetIsInBounds(double offset) {
@@ -165,16 +146,16 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
   }
 
   Future _startToEndAnimation({ double velocity }) {
-    _stopAnimations();
+    _animation.stop();
     Simulation simulation =
       _createSnapSimulation(velocity) ?? _createFlingSimulation(velocity ?? 0.0);
     if (simulation == null)
       return new Future.value();
-    return _toEndAnimation.start(simulation);
+    return _animation.animateWith(simulation);
   }
 
   void dispose() {
-    _stopAnimations();
+    _animation.stop();
     super.dispose();
   }
 
@@ -193,12 +174,12 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
       return new Future.value();
 
     if (duration == null) {
-      _stopAnimations();
+      _animation.stop();
       _setScrollOffset(newScrollOffset);
       return new Future.value();
     }
 
-    return _startToOffsetAnimation(newScrollOffset, duration, curve);
+    return _animateTo(newScrollOffset, duration, curve);
   }
 
   Future scrollBy(double scrollDelta, { Duration duration, Curve curve }) {
@@ -209,7 +190,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
   Future fling(Offset velocity) {
     if (velocity != Offset.zero)
       return _startToEndAnimation(velocity: _scrollVelocity(velocity));
-    if (!_toEndAnimation.isAnimating && (_toOffsetAnimation == null || !_toOffsetAnimation.isAnimating))
+    if (!_animation.isAnimating)
       return settleScrollOffset();
     return new Future.value();
   }
@@ -226,7 +207,7 @@ abstract class ScrollableState<T extends Scrollable> extends State<T> {
   }
 
   void _handlePointerDown(_) {
-    _stopAnimations();
+    _animation.stop();
   }
 
   void _handleDragUpdate(double delta) {
@@ -337,7 +318,7 @@ class ScrollableViewportState extends ScrollableState<ScrollableViewport> {
     });
   }
   void _updateScrollBehaviour() {
-    // if you don't call this from build() or syncConstructorArguments(), you must call it from setState().
+    // if you don't call this from build(), you must call it from setState().
     scrollTo(scrollBehavior.updateExtents(
       contentExtent: _childSize,
       containerExtent: _viewportSize,

packages/flutter/lib/src/widgets/snack_bar.dart

@@ -2,10 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-
 import 'package:sky/animation.dart';
-import 'package:sky/painting.dart';
+import 'package:sky/gestures.dart';
 import 'package:sky/material.dart';
+import 'package:sky/painting.dart';
 import 'package:sky/src/widgets/animated_component.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
@@ -28,7 +28,7 @@ class SnackBarAction extends StatelessComponent {
   }
 
   final String label;
-  final Function onPressed;
+  final GestureTapCallback onPressed;
 
   Widget build(BuildContext) {
     return new GestureDetector(
@@ -49,7 +49,7 @@ class SnackBar extends AnimatedComponent {
     this.actions,
     bool showing,
     this.onDismissed
-  }) : super(key: key, direction: showing ? Direction.forward : Direction.reverse, duration: _kSlideInDuration) {
+  }) : super(key: key, direction: showing ? AnimationDirection.forward : AnimationDirection.reverse, duration: _kSlideInDuration) {
     assert(content != null);
   }
 

packages/flutter/lib/src/widgets/statistics_overlay.dart

+// 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 'package:sky/src/widgets/framework.dart';
+import 'package:sky/src/rendering/statistics_box.dart';
+
+/// The options that control whether the statistics overlay displays certain
+/// aspects of the compositor
+enum StatisticsOption {
+  /// Display the frame time and FPS of the last frame rendered. This field is
+  /// updated every frame.
+  ///
+  /// This is the time spent by the rasterizer as it tries
+  /// to convert the layer tree obtained from the widgets into OpenGL commands
+  /// and tries to flush them onto the screen. When the total time taken by this
+  /// step exceeds the frame slice, a frame is lost.
+  displayRasterizerStatistics,
+  /// Display the rasterizer frame times as they change over a set period of
+  /// time in the form of a graph. The y axis of the graph denotes the total
+  /// time spent by the rasterizer as a fraction of the total frame slice. When
+  /// the bar turns red, a frame is lost.
+  visualizeRasterizerStatistics,
+  /// Display the frame time and FPS at which the interface can construct a
+  /// layer tree for the rasterizer (whose behavior is described above) to
+  /// consume.
+  ///
+  /// This involves all layout, animations, etc. When the total time taken by
+  /// this step exceeds the frame slice, a frame is lost.
+  displayEngineStatistics,
+  /// Display the engine frame times as they change over a set period of time
+  /// in the form of a graph. The y axis of the graph denotes the total time
+  /// spent by the eninge as a fraction of the total frame slice. When the bar
+  /// turns red, a frame is lost.
+  visualizeEngineStatistics,
+}
+
+class StatisticsOverlay extends LeafRenderObjectWidget {
+
+  /// Create a statistics overlay that only displays specific statistics. The
+  /// mask is created by shifting 1 by the index of the specific StatisticOption
+  /// to enable.
+  StatisticsOverlay({ this.optionsMask, Key key }) : super(key: key);
+
+  /// Create a statistics overaly that displays all available statistics
+  StatisticsOverlay.allEnabled({ Key key }) : super(key: key), optionsMask = (
+    1 << StatisticsOption.displayRasterizerStatistics.index |
+    1 << StatisticsOption.visualizeRasterizerStatistics.index |
+    1 << StatisticsOption.displayEngineStatistics.index |
+    1 << StatisticsOption.visualizeEngineStatistics.index
+  );
+
+  final int optionsMask;
+
+  StatisticsBox createRenderObject() => new StatisticsBox(optionsMask: optionsMask);
+
+  void updateRenderObject(StatisticsBox renderObject, RenderObjectWidget oldWidget) {
+    renderObject.optionsMask = optionsMask;
+  }
+}

packages/flutter/lib/src/widgets/tabs.dart

@@ -7,12 +7,12 @@ import 'dart:sky' as sky;
 
 import 'package:newton/newton.dart';
 import 'package:sky/animation.dart';
+import 'package:sky/gestures.dart';
+import 'package:sky/material.dart';
 import 'package:sky/painting.dart';
 import 'package:sky/rendering.dart';
-import 'package:sky/material.dart';
 import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/gesture_detector.dart';
 import 'package:sky/src/widgets/icon.dart';
 import 'package:sky/src/widgets/ink_well.dart';
 import 'package:sky/src/widgets/scrollable.dart';
@@ -307,6 +307,7 @@ class TabLabel {
 class Tab extends StatelessComponent {
   Tab({
     Key key,
+    this.onSelected,
     this.label,
     this.color,
     this.selected: false,
@@ -315,6 +316,7 @@ class Tab extends StatelessComponent {
     assert(label.text != null || label.icon != null);
   }
 
+  final GestureTapCallback onSelected;
   final TabLabel label;
   final Color color;
   final bool selected;
@@ -359,7 +361,10 @@ class Tab extends StatelessComponent {
       padding: _kTabLabelPadding
     );
 
-    return new InkWell(child: centeredLabel);
+    return new InkWell(
+      onTap: onSelected,
+      child: centeredLabel
+    );
   }
 }
 
@@ -403,16 +408,16 @@ class TabBar extends Scrollable {
 class TabBarState extends ScrollableState<TabBar> {
   void initState() {
     super.initState();
-    _indicatorAnimation = new ValueAnimation<Rect>()
+    _indicatorAnimation = new ValuePerformance<Rect>()
       ..duration = _kTabBarScroll
-      ..variable = new AnimatedRect(null, curve: ease);
+      ..variable = new AnimatedRectValue(null, curve: ease);
     scrollBehavior.isScrollable = config.isScrollable;
   }
 
   Size _tabBarSize;
   Size _viewportSize = Size.zero;
   List<double> _tabWidths;
-  ValueAnimation<Rect> _indicatorAnimation;
+  ValuePerformance<Rect> _indicatorAnimation;
 
   void didUpdateConfig(TabBar oldConfig) {
     super.didUpdateConfig(oldConfig);
@@ -420,7 +425,7 @@ class TabBarState extends ScrollableState<TabBar> {
       scrollTo(0.0);
   }
 
-  AnimatedRect get _indicatorRect => _indicatorAnimation.variable;
+  AnimatedRectValue get _indicatorRect => _indicatorAnimation.variable;
 
   void _startIndicatorAnimation(int fromTabIndex, int toTabIndex) {
     _indicatorRect
@@ -458,7 +463,7 @@ class TabBarState extends ScrollableState<TabBar> {
       .clamp(scrollBehavior.minScrollOffset, scrollBehavior.maxScrollOffset);
   }
 
-  void _handleTap(int tabIndex) {
+  void _handleTabSelected(int tabIndex) {
     if (tabIndex != config.selectedIndex) {
       if (_tabWidths != null) {
         if (config.isScrollable)
@@ -471,14 +476,12 @@ class TabBarState extends ScrollableState<TabBar> {
   }
 
   Widget _toTab(TabLabel label, int tabIndex, Color color, Color selectedColor) {
-    return new GestureDetector(
-      onTap: () => _handleTap(tabIndex),
-      child: new Tab(
+    return new Tab(
+      onSelected: () => _handleTabSelected(tabIndex),
       label: label,
       color: color,
       selected: tabIndex == config.selectedIndex,
       selectedColor: selectedColor
-      )
     );
   }
 

packages/flutter/lib/src/widgets/transitions.dart

@@ -7,7 +7,7 @@ import 'package:sky/src/widgets/basic.dart';
 import 'package:sky/src/widgets/framework.dart';
 import 'package:vector_math/vector_math_64.dart';
 
-export 'package:sky/animation.dart' show Direction;
+export 'package:sky/animation.dart' show AnimationDirection;
 
 abstract class TransitionComponent extends StatefulComponent {
   TransitionComponent({
@@ -17,7 +17,7 @@ abstract class TransitionComponent extends StatefulComponent {
     assert(performance != null);
   }
 
-  final WatchableAnimationPerformance performance;
+  final PerformanceView performance;
 
   Widget build(BuildContext context);
 
@@ -57,7 +57,7 @@ abstract class TransitionWithChild extends TransitionComponent {
   TransitionWithChild({
     Key key,
     this.child,
-    WatchableAnimationPerformance performance
+    PerformanceView performance
   }) : super(key: key, performance: performance);
 
   final Widget child;
@@ -71,7 +71,7 @@ class SlideTransition extends TransitionWithChild {
   SlideTransition({
     Key key,
     this.position,
-    WatchableAnimationPerformance performance,
+    PerformanceView performance,
     Widget child
   }) : super(key: key,
              performance: performance,
@@ -91,7 +91,7 @@ class FadeTransition extends TransitionWithChild {
   FadeTransition({
     Key key,
     this.opacity,
-    WatchableAnimationPerformance performance,
+    PerformanceView performance,
     Widget child
   }) : super(key: key,
              performance: performance,
@@ -109,7 +109,7 @@ class ColorTransition extends TransitionWithChild {
   ColorTransition({
     Key key,
     this.color,
-    WatchableAnimationPerformance performance,
+    PerformanceView performance,
     Widget child
   }) : super(key: key,
              performance: performance,
@@ -131,7 +131,7 @@ class SquashTransition extends TransitionWithChild {
     Key key,
     this.width,
     this.height,
-    WatchableAnimationPerformance performance,
+    PerformanceView performance,
     Widget child
   }) : super(key: key,
              performance: performance,
@@ -156,7 +156,7 @@ class BuilderTransition extends TransitionComponent {
     Key key,
     this.variables,
     this.builder,
-    WatchableAnimationPerformance performance
+    PerformanceView performance
   }) : super(key: key,
              performance: performance);
 

packages/flutter/lib/widgets.dart

@@ -6,6 +6,7 @@
 library widgets;
 
 export 'src/widgets/animated_component.dart';
+export 'src/widgets/animated_container.dart';
 export 'src/widgets/app.dart';
 export 'src/widgets/basic.dart';
 export 'src/widgets/binding.dart';
@@ -43,6 +44,7 @@ export 'src/widgets/radio.dart';
 export 'src/widgets/raised_button.dart';
 export 'src/widgets/scaffold.dart';
 export 'src/widgets/scrollable.dart';
+export 'src/widgets/statistics_overlay.dart';
 export 'src/widgets/snack_bar.dart';
 export 'src/widgets/switch.dart';
 export 'src/widgets/tabs.dart';

packages/flutter_sprites/lib/node.dart

@@ -131,6 +131,19 @@ class Node {
 
   void set rotation(double rotation) {
     assert(rotation != null);
+
+    if (_physicsBody != null && parent is PhysicsNode) {
+      PhysicsNode physicsNode = parent;
+      physicsNode._updateRotation(this.physicsBody, rotation);
+      return;
+    }
+
+    _rotation = rotation;
+    invalidateTransformMatrix();
+  }
+
+  void _setRotationFromPhysics(double rotation) {
+    assert(rotation != null);
     _rotation = rotation;
     invalidateTransformMatrix();
   }
@@ -142,6 +155,19 @@ class Node {
 
   void set position(Point position) {
     assert(position != null);
+
+    if (_physicsBody != null && parent is PhysicsNode) {
+      PhysicsNode physicsNode = parent;
+      physicsNode._updatePosition(this.physicsBody, position);
+      return;
+    }
+
+    _position = position;
+    invalidateTransformMatrix();
+  }
+
+  void _setPositionFromPhysics(Point position) {
+    assert(position != null);
     _position = position;
     invalidateTransformMatrix();
   }
@@ -609,4 +635,24 @@ class Node {
   bool handleEvent(SpriteBoxEvent event) {
     return false;
   }
+
+  // Physics
+
+  PhysicsBody _physicsBody;
+
+  PhysicsBody get physicsBody => _physicsBody;
+
+  set physicsBody(PhysicsBody physicsBody) {
+    if (parent != null) {
+      assert(parent is PhysicsNode);
+
+      if (physicsBody == null) {
+        physicsBody._detach();
+      } else {
+        physicsBody._attach(parent, this);
+      }
+    }
+
+    _physicsBody = physicsBody;
+  }
 }

packages/flutter_sprites/lib/physics_body.dart

+part of skysprites;
+
+enum PhysicsBodyType {
+    static,
+    dynamic
+}
+
+class PhysicsBody {
+  PhysicsBody(this.shape, {
+    this.tag: null,
+    this.type: PhysicsBodyType.dynamic,
+    this.density: 1.0,
+    this.friction: 0.0,
+    this.restitution: 0.0,
+    this.isSensor: false,
+    this.linearVelocity: Offset.zero,
+    this.angularVelocity: 0.0,
+    this.linearDampening: 0.0,
+    this.angularDampening: 0.0,
+    this.allowSleep: true,
+    this.awake: true,
+    this.fixedRotation: false,
+    this.bullet: false,
+    this.active: true,
+    this.gravityScale: 1.0
+  });
+
+  Object tag;
+
+  PhysicsShape shape;
+
+  PhysicsBodyType type;
+
+  double density;
+  double friction;
+  double restitution;
+  bool isSensor;
+
+  Offset linearVelocity;
+  double angularVelocity;
+
+  double linearDampening;
+
+  double angularDampening;
+
+  bool allowSleep;
+
+  bool awake;
+
+  bool fixedRotation;
+
+  bool bullet;
+
+  bool active;
+
+  double gravityScale;
+
+  PhysicsNode _physicsNode;
+  Node _node;
+
+  box2d.Body _body;
+
+  bool _attached = false;
+
+  void _attach(PhysicsNode physicsNode, Node node) {
+    assert(_attached == false);
+
+    // Create BodyDef
+    box2d.BodyDef bodyDef = new box2d.BodyDef();
+    bodyDef.linearVelocity = new Vector2(linearVelocity.dx, linearVelocity.dy);
+    bodyDef.angularVelocity = angularVelocity;
+    bodyDef.linearDamping = linearDampening;
+    bodyDef.angularDamping = angularDampening;
+    bodyDef.allowSleep = allowSleep;
+    bodyDef.awake = awake;
+    bodyDef.fixedRotation = fixedRotation;
+    bodyDef.bullet = bullet;
+    bodyDef.active = active;
+    bodyDef.gravityScale = gravityScale;
+    if (type == PhysicsBodyType.dynamic)
+      bodyDef.type = box2d.BodyType.DYNAMIC;
+    else
+      bodyDef.type = box2d.BodyType.STATIC;
+
+    double conv = physicsNode.b2WorldToNodeConversionFactor;
+    bodyDef.position = new Vector2(node.position.x / conv, node.position.y / conv);
+    bodyDef.angle = radians(node.rotation);
+
+    // Create Body
+    _body = physicsNode.b2World.createBody(bodyDef);
+
+    // Create FixtureDef
+    box2d.FixtureDef fixtureDef = new box2d.FixtureDef();
+    fixtureDef.friction = friction;
+    fixtureDef.restitution = restitution;
+    fixtureDef.density = density;
+    fixtureDef.isSensor = isSensor;
+
+    // Get shapes
+    List<box2d.Shape> b2Shapes = [];
+    List<PhysicsShape> physicsShapes = [];
+    _addB2Shapes(physicsNode, shape, b2Shapes, physicsShapes);
+
+    // Create fixtures
+    for (int i = 0; i < b2Shapes.length; i++) {
+      box2d.Shape b2Shape = b2Shapes[i];
+      PhysicsShape physicsShape = physicsShapes[i];
+
+      fixtureDef.shape = b2Shape;
+      box2d.Fixture fixture = _body.createFixtureFromFixtureDef(fixtureDef);
+      fixture.userData = physicsShape;
+    }
+    _body.userData = this;
+
+    _physicsNode = physicsNode;
+    _node = node;
+
+    _attached = true;
+  }
+
+  void _detach() {
+    if (_attached) {
+      _physicsNode._bodiesScheduledForDestruction.add(_body);
+      _attached = false;
+    }
+  }
+
+  void _addB2Shapes(PhysicsNode physicsNode, PhysicsShape shape, List<box2d.Shape> b2Shapes, List<PhysicsShape> physicsShapes) {
+    if (shape is PhysicsShapeGroup) {
+      for (PhysicsShape child in shape.shapes) {
+        _addB2Shapes(physicsNode, child, b2Shapes, physicsShapes);
+      }
+    } else {
+      b2Shapes.add(shape.getB2Shape(physicsNode));
+      physicsShapes.add(shape);
+    }
+  }
+}

packages/flutter_sprites/lib/physics_node.dart

+part of skysprites;
+
+enum PhysicsContactType {
+  preSolve,
+  postSolve,
+  begin,
+  end
+}
+
+typedef void PhysicsContactCallback(PhysicsContactType type, PhysicsContact contact);
+
+class PhysicsNode extends Node {
+  PhysicsNode(Offset gravity) {
+    b2World = new box2d.World.withGravity(
+      new Vector2(
+        gravity.dx / b2WorldToNodeConversionFactor,
+        gravity.dy / b2WorldToNodeConversionFactor));
+    _init();
+  }
+
+  PhysicsNode.fromB2World(this.b2World, this.b2WorldToNodeConversionFactor) {
+    _init();
+  }
+
+  void _init() {
+    _contactHandler = new _ContactHandler(this);
+    b2World.setContactListener(_contactHandler);
+  }
+
+  box2d.World b2World;
+
+  _ContactHandler _contactHandler;
+
+  List<box2d.Body> _bodiesScheduledForDestruction = [];
+
+  double b2WorldToNodeConversionFactor = 500.0;
+
+  Offset get gravity {
+    Vector2 g = b2World.getGravity();
+    return new Offset(g.x, g.y);
+  }
+
+  set gravity(Offset gravity) {
+    // Convert from points/s^2 to m/s^2
+    b2World.setGravity(new Vector2(gravity.dx / b2WorldToNodeConversionFactor,
+      gravity.dy / b2WorldToNodeConversionFactor));
+  }
+
+  bool get allowSleep => b2World.isAllowSleep();
+
+  set allowSleep(bool allowSleep) {
+    b2World.setAllowSleep(allowSleep);
+  }
+
+  bool get subStepping => b2World.isSubStepping();
+
+  set subStepping(bool subStepping) {
+    b2World.setSubStepping(subStepping);
+  }
+
+  void _stepPhysics(double dt) {
+    // Remove bodies that were marked for destruction during the update phase
+    _removeBodiesScheduledForDestruction();
+
+    // Calculate a step in the simulation
+    b2World.stepDt(dt, 10, 10);
+
+    // Iterate over the bodies
+    for (box2d.Body b2Body = b2World.bodyList; b2Body != null; b2Body = b2Body.getNext()) {
+      // Update visual position and rotation
+      PhysicsBody body = b2Body.userData;
+      body._node._setPositionFromPhysics(new Point(
+        b2Body.position.x * b2WorldToNodeConversionFactor,
+        b2Body.position.y * b2WorldToNodeConversionFactor
+      ));
+
+      body._node._setRotationFromPhysics(degrees(b2Body.getAngle()));
+    }
+
+    // Remove bodies that were marked for destruction during the simulation
+    _removeBodiesScheduledForDestruction();
+  }
+
+  void _removeBodiesScheduledForDestruction() {
+    for (box2d.Body b2Body in _bodiesScheduledForDestruction) {
+      b2World.destroyBody(b2Body);
+    }
+    _bodiesScheduledForDestruction.clear();
+  }
+
+  void _updatePosition(PhysicsBody body, Point position) {
+    Vector2 newPos = new Vector2(
+      position.x / b2WorldToNodeConversionFactor,
+      position.y / b2WorldToNodeConversionFactor
+    );
+    double angle = body._body.getAngle();
+    body._body.setTransform(newPos, angle);
+    body._body.setAwake(true);
+  }
+
+  void _updateRotation(PhysicsBody body, double rotation) {
+    Vector2 pos = body._body.position;
+    double newAngle = radians(rotation);
+    body._body.setTransform(pos, newAngle);
+    body._body.setAwake(true);
+  }
+
+  void addChild(Node node) {
+    super.addChild(node);
+    if (node.physicsBody != null) {
+      node.physicsBody._attach(this, node);
+    }
+  }
+
+  void removeChild(Node node) {
+    super.removeChild(node);
+    if (node.physicsBody != null) {
+      node.physicsBody._detach();
+    }
+  }
+
+  void addContactCallback(PhysicsContactCallback callback, Object tagA, Object tagB, [PhysicsContactType type]) {
+    _contactHandler.addContactCallback(callback, tagA, tagB, type);
+  }
+
+  void paint(PaintingCanvas canvas) {
+    super.paint(canvas);
+    paintDebug(canvas);
+  }
+
+  void paintDebug(PaintingCanvas canvas) {
+    Paint shapePaint = new Paint();
+    shapePaint.setStyle(sky.PaintingStyle.stroke);
+    shapePaint.strokeWidth = 1.0;
+
+    for (box2d.Body body = b2World.bodyList; body != null; body = body.getNext()) {
+      canvas.save();
+
+      Point point = new Point(
+        body.position.x * b2WorldToNodeConversionFactor,
+        body.position.y * b2WorldToNodeConversionFactor);
+
+      canvas.translate(point.x, point.y);
+      canvas.rotate(body.getAngle());
+
+      if (body.getType() == box2d.BodyType.DYNAMIC) {
+        if (body.isAwake())
+          shapePaint.color = new Color(0xff00ff00);
+        else
+          shapePaint.color = new Color(0xff666666);
+      }
+      else if (body.getType() == box2d.BodyType.STATIC)
+        shapePaint.color = new Color(0xffff0000);
+      else if (body.getType() == box2d.BodyType.KINEMATIC)
+        shapePaint.color = new Color(0xffff9900);
+
+      for (box2d.Fixture fixture = body.getFixtureList(); fixture != null; fixture = fixture.getNext()) {
+        box2d.Shape shape = fixture.getShape();
+
+        if (shape.shapeType == box2d.ShapeType.CIRCLE) {
+          box2d.CircleShape circle = shape;
+          Point cp = new Point(
+            circle.p.x * b2WorldToNodeConversionFactor,
+            circle.p.y * b2WorldToNodeConversionFactor
+          );
+          double radius = circle.radius * b2WorldToNodeConversionFactor;
+          canvas.drawCircle(cp, radius, shapePaint);
+        } else if (shape.shapeType == box2d.ShapeType.POLYGON) {
+          box2d.PolygonShape poly = shape;
+          List<Point> points = [];
+          for (int i = 0; i < poly.getVertexCount(); i++) {
+            Vector2 vertex = poly.getVertex(i);
+            Point pt = new Point(
+              vertex.x * b2WorldToNodeConversionFactor,
+              vertex.y * b2WorldToNodeConversionFactor
+            );
+            points.add(pt);
+          }
+          if (points.length >= 2) {
+            for (int i = 0; i < points.length; i++) {
+              canvas.drawLine(points[i], points[(i + 1) % points.length], shapePaint);
+            }
+          }
+        }
+      }
+      canvas.restore();
+    }
+  }
+}
+
+class PhysicsContact {
+  PhysicsContact(
+    this.nodeA,
+    this.nodeB,
+    this.shapeA,
+    this.shapeB,
+    this.isTouching,
+    this.isEnabled
+  );
+
+  final Node nodeA;
+  final Node nodeB;
+  final PhysicsShape shapeA;
+  final PhysicsShape shapeB;
+  final isTouching;
+  bool isEnabled;
+}
+
+class _ContactCallbackInfo {
+  _ContactCallbackInfo(this.callback, this.tagA, this.tagB, this.type);
+
+  PhysicsContactCallback callback;
+  Object tagA;
+  Object tagB;
+  PhysicsContactType type;
+}
+
+class _ContactHandler extends box2d.ContactListener {
+  _ContactHandler(this.physicsNode);
+
+  PhysicsNode physicsNode;
+
+  List<_ContactCallbackInfo> callbackInfos = [];
+
+  void addContactCallback(PhysicsContactCallback callback, Object tagA, Object tagB, PhysicsContactType type) {
+    callbackInfos.add(new _ContactCallbackInfo(callback, tagA, tagB, type));
+  }
+
+  void handleCallback(PhysicsContactType type, box2d.Contact b2Contact, box2d.Manifold oldManifold, box2d.ContactImpulse impulse) {
+    // Get info about the contact
+    PhysicsBody bodyA = b2Contact.fixtureA.getBody().userData;
+    PhysicsBody bodyB = b2Contact.fixtureB.getBody().userData;
+    box2d.Fixture fixtureA = b2Contact.fixtureA;
+    box2d.Fixture fixtureB = b2Contact.fixtureB;
+
+    // Match callback with added callbacks
+    for (_ContactCallbackInfo info in callbackInfos) {
+      // Check that type is matching
+      if (info.type != null && info.type != type)
+        continue;
+
+      // Check if there is a match
+      bool matchA = (info.tagA == null) || info.tagA == bodyA.tag;
+      bool matchB = (info.tagB == null) || info.tagB == bodyB.tag;
+
+      bool match = (matchA && matchB);
+      if (!match) {
+        // Check if there is a match if we swap a & b
+        bool matchA = (info.tagA == null) || info.tagA == bodyB.tag;
+        bool matchB = (info.tagB == null) || info.tagB == bodyA.tag;
+
+        match = (matchA && matchB);
+        if (match) {
+          // Swap a & b
+          PhysicsBody tempBody = bodyA;
+          bodyA = bodyB;
+          bodyB = tempBody;
+
+          box2d.Fixture tempFixture = fixtureA;
+          fixtureA = fixtureB;
+          fixtureB = tempFixture;
+        }
+      }
+
+      if (match) {
+        // We have contact and a matched callback, setup contact info
+        PhysicsContact contact = new PhysicsContact(
+          bodyA._node,
+          bodyB._node,
+          fixtureA.userData,
+          fixtureB.userData,
+          b2Contact.isTouching(),
+          b2Contact.isEnabled()
+        );
+
+        if (type == PhysicsContactType.postSolve) {
+
+        }
+
+        // Make callback
+        info.callback(type, contact);
+
+        // Update Box2D contact
+        b2Contact.setEnabled(contact.isEnabled);
+      }
+    }
+  }
+
+  void beginContact(box2d.Contact contact) {
+    handleCallback(PhysicsContactType.begin, contact, null, null);
+  }
+
+  void endContact(box2d.Contact contact) {
+    handleCallback(PhysicsContactType.end, contact, null, null);
+  }
+
+  void preSolve(box2d.Contact contact, box2d.Manifold oldManifold) {
+    handleCallback(PhysicsContactType.preSolve, contact, oldManifold, null);
+  }
+  void postSolve(box2d.Contact contact, box2d.ContactImpulse impulse) {
+    handleCallback(PhysicsContactType.postSolve, contact, null, impulse);
+  }
+}

packages/flutter_sprites/lib/physics_shape.dart

+part of skysprites;
+
+abstract class PhysicsShape {
+
+  box2d.Shape _b2Shape;
+
+  Object userObject;
+
+  box2d.Shape getB2Shape(PhysicsNode node) {
+    if (_b2Shape == null) {
+      _b2Shape = _createB2Shape(node);
+    }
+    return _b2Shape;
+  }
+
+  box2d.Shape _createB2Shape(PhysicsNode node);
+}
+
+class PhysicsShapeCircle extends PhysicsShape {
+  PhysicsShapeCircle(this.point, this.radius);
+
+  final Point point;
+  final double radius;
+
+  box2d.Shape _createB2Shape(PhysicsNode node) {
+    box2d.CircleShape shape = new box2d.CircleShape();
+    shape.p.x = point.x / node.b2WorldToNodeConversionFactor;
+    shape.p.y = point.y / node.b2WorldToNodeConversionFactor;
+    shape.radius = radius / node.b2WorldToNodeConversionFactor;
+    return shape;
+  }
+}
+
+class PhysicsShapePolygon extends PhysicsShape {
+
+  PhysicsShapePolygon(this.points);
+
+  final List<Point> points;
+
+  box2d.Shape _createB2Shape(PhysicsNode node) {
+    List<Vector2> vectors = [];
+    for (Point point in points) {
+      Vector2 vec = new Vector2(
+        point.x / node.b2WorldToNodeConversionFactor,
+        point.y / node.b2WorldToNodeConversionFactor
+      );
+      vectors.add(vec);
+    }
+
+    box2d.PolygonShape shape = new box2d.PolygonShape();
+    shape.set(vectors, vectors.length);
+    return shape;
+  }
+}
+
+class PhysicsShapeGroup extends PhysicsShape {
+
+  PhysicsShapeGroup(this.shapes);
+
+  final List<PhysicsShape> shapes;
+
+  box2d.Shape _createB2Shape(PhysicsNode node) {
+    return null;
+  }
+}

packages/flutter_sprites/lib/skysprites.dart

@@ -10,6 +10,7 @@ import 'dart:math' as math;
 import 'dart:typed_data';
 import 'dart:sky' as sky;
 
+import 'package:box2d/box2d.dart' as box2d;
 import 'package:mojo/core.dart';
 import 'package:sky_services/media/media.mojom.dart';
 import 'package:sky/animation.dart';
@@ -31,6 +32,9 @@ part 'node.dart';
 part 'node3d.dart';
 part 'node_with_size.dart';
 part 'particle_system.dart';
+part 'physics_body.dart';
+part 'physics_node.dart';
+part 'physics_shape.dart';
 part 'sound.dart';
 part 'sound_manager.dart';
 part 'sprite.dart';

packages/flutter_sprites/lib/sprite_box.dart

@@ -47,7 +47,7 @@ class SpriteBox extends RenderBox {
   }
 
   // Tracking of frame rate and updates
-  double _lastTimeStamp;
+  Duration _lastTimeStamp;
   double _frameRate = 0.0;
 
   double get frameRate => _frameRate;
@@ -76,6 +76,8 @@ class SpriteBox extends RenderBox {
 
   List<Node> _constrainedNodes;
 
+  List<PhysicsNode> _physicsNodes;
+
   Rect _visibleArea;
 
   Rect get visibleArea {
@@ -84,6 +86,8 @@ class SpriteBox extends RenderBox {
     return _visibleArea;
   }
 
+  bool _initialized = false;
+
   // Setup
 
   /// Creates a new SpriteBox with a node as its content, by default uses letterboxing.
@@ -134,19 +138,22 @@ class SpriteBox extends RenderBox {
     size = constraints.biggest;
     _invalidateTransformMatrix();
     _callSpriteBoxPerformedLayout(_rootNode);
+    _initialized = true;
   }
 
   // Adding and removing nodes
 
-  _registerNode(Node node) {
+  void _registerNode(Node node) {
     _actionControllers = null;
     _eventTargets = null;
+    _physicsNodes = null;
     if (node == null || node.constraints != null) _constrainedNodes = null;
   }
 
-  _deregisterNode(Node node) {
+  void _deregisterNode(Node node) {
     _actionControllers = null;
     _eventTargets = null;
+    _physicsNodes = null;
     if (node == null || node.constraints != null) _constrainedNodes = null;
   }
 
@@ -345,21 +352,25 @@ class SpriteBox extends RenderBox {
     scheduler.requestAnimationFrame(_tick);
   }
 
-  void _tick(double timeStamp) {
+  void _tick(Duration timeStamp) {
     if (!attached)
       return;
 
     // Calculate delta and frame rate
-    if (_lastTimeStamp == null) _lastTimeStamp = timeStamp;
-    double delta = (timeStamp - _lastTimeStamp) / 1000;
+    if (_lastTimeStamp == null)
+      _lastTimeStamp = timeStamp;
+    double delta = (timeStamp - _lastTimeStamp).inMicroseconds.toDouble() / Duration.MICROSECONDS_PER_SECOND;
     _lastTimeStamp = timeStamp;
 
     _frameRate = 1.0/delta;
 
+    if (_initialized) {
       _callConstraintsPreUpdate(delta);
       _runActions(delta);
       _callUpdate(_rootNode, delta);
+      _callStepPhysics(delta);
       _callConstraintsConstrain(delta);
+    }
 
     // Schedule next update
     _scheduleTick();
@@ -370,20 +381,26 @@ class SpriteBox extends RenderBox {
 
   void _runActions(double dt) {
     if (_actionControllers == null) {
-      _actionControllers = [];
-      _addActionControllers(_rootNode, _actionControllers);
+      _rebuildActionControllersAndPhysicsNodes();
     }
     for (ActionController actions in _actionControllers) {
       actions.step(dt);
     }
   }
 
-  void _addActionControllers(Node node, List<ActionController> controllers) {
-    if (node._actions != null) controllers.add(node._actions);
+  void _rebuildActionControllersAndPhysicsNodes() {
+    _actionControllers = [];
+    _physicsNodes = [];
+    _addActionControllersAndPhysicsNodes(_rootNode);
+  }
+
+  void _addActionControllersAndPhysicsNodes(Node node) {
+    if (node._actions != null) _actionControllers.add(node._actions);
+    if (node is PhysicsNode) _physicsNodes.add(node);
 
     for (int i = node.children.length - 1; i >= 0; i--) {
       Node child = node.children[i];
-      _addActionControllers(child, controllers);
+      _addActionControllersAndPhysicsNodes(child);
     }
   }
 
@@ -397,6 +414,15 @@ class SpriteBox extends RenderBox {
     }
   }
 
+  void _callStepPhysics(double dt) {
+    if (_physicsNodes == null)
+      _rebuildActionControllersAndPhysicsNodes();
+
+    for (PhysicsNode physicsNode in _physicsNodes) {
+      physicsNode._stepPhysics(dt);
+    }
+  }
+
   void _callConstraintsPreUpdate(double dt) {
     if (_constrainedNodes == null) {
       _constrainedNodes = [];

packages/flutter_sprites/pubspec.yaml

@@ -6,6 +6,7 @@ homepage: http://flutter.io
 dependencies:
   sky: ">=0.0.36 < 0.1.0"
   sky_tools: ">=0.0.10 < 0.1.0"
+  box2d: any
 dependency_overrides:
   sky:
     path: ../sky/packages/sky

packages/unit/test/animation/scheduler_test.dart

@@ -8,18 +8,18 @@ void main() {
     bool firstCallbackRan = false;
     bool secondCallbackRan = false;
 
-    void firstCallback(double timeStamp) {
+    void firstCallback(Duration timeStamp) {
       expect(firstCallbackRan, isFalse);
       expect(secondCallbackRan, isFalse);
-      expect(timeStamp, equals(16.0));
+      expect(timeStamp.inMilliseconds, equals(16));
       firstCallbackRan = true;
       scheduler.cancelAnimationFrame(secondId);
     }
 
-    void secondCallback(double timeStamp) {
+    void secondCallback(Duration timeStamp) {
       expect(firstCallbackRan, isTrue);
       expect(secondCallbackRan, isFalse);
-      expect(timeStamp, equals(16.0));
+      expect(timeStamp.inMilliseconds, equals(16));
       secondCallbackRan = true;
     }
 

packages/unit/test/widget/animated_container_test.dart

+import 'package:sky/rendering.dart';
+import 'package:sky/widgets.dart';
+import 'package:test/test.dart';
+
+import 'widget_tester.dart';
+
+void main() {
+  test('AnimatedContainer control test', () {
+    testWidgets((WidgetTester tester) {
+      GlobalKey key = new GlobalKey();
+
+      BoxDecoration decorationA = new BoxDecoration(
+        backgroundColor: new Color(0xFF00FF00)
+      );
+
+      BoxDecoration decorationB = new BoxDecoration(
+        backgroundColor: new Color(0xFF0000FF)
+      );
+
+      tester.pumpWidget(
+        new AnimatedContainer(
+          key: key,
+          duration: const Duration(milliseconds: 200),
+          decoration: decorationA
+        )
+      );
+
+      RenderDecoratedBox box = key.currentState.context.findRenderObject();
+      expect(box.decoration.backgroundColor, equals(decorationA.backgroundColor));
+
+      tester.pumpWidget(
+        new AnimatedContainer(
+          key: key,
+          duration: const Duration(milliseconds: 200),
+          decoration: decorationB
+        )
+      );
+
+      expect(key.currentState.context.findRenderObject(), equals(box));
+      expect(box.decoration.backgroundColor, equals(decorationA.backgroundColor));
+
+      tester.pump(const Duration(seconds: 1));
+
+      expect(box.decoration.backgroundColor, equals(decorationB.backgroundColor));
+
+    });
+  });
+}

packages/unit/test/widget/dismissable_test.dart

+import 'package:sky/rendering.dart';
 import 'package:sky/widgets.dart';
 import 'package:test/test.dart';
 
@@ -44,13 +45,11 @@ Widget widgetBuilder() {
   );
 }
 
-void dismissItem(WidgetTester tester, int item, { DismissDirection gestureDirection }) {
+void dismissElement(WidgetTester tester, Element itemElement, { DismissDirection gestureDirection }) {
+  assert(itemElement != null);
   assert(gestureDirection != DismissDirection.horizontal);
   assert(gestureDirection != DismissDirection.vertical);
 
-  Element itemElement = tester.findText(item.toString());
-  expect(itemElement, isNotNull);
-
   Point downLocation;
   Point upLocation;
   switch(gestureDirection) {
@@ -84,12 +83,35 @@ void dismissItem(WidgetTester tester, int item, { DismissDirection gestureDirect
   tester.dispatchEvent(pointer.down(downLocation), downLocation);
   tester.dispatchEvent(pointer.move(upLocation), downLocation);
   tester.dispatchEvent(pointer.up(), downLocation);
+}
+
+void dismissItem(WidgetTester tester, int item, { DismissDirection gestureDirection }) {
+  assert(gestureDirection != DismissDirection.horizontal);
+  assert(gestureDirection != DismissDirection.vertical);
+
+  Element itemElement = tester.findText(item.toString());
+  expect(itemElement, isNotNull);
+
+  dismissElement(tester, itemElement, gestureDirection: gestureDirection);
 
   tester.pumpWidget(widgetBuilder()); // start the resize animation
   tester.pumpWidget(widgetBuilder(), const Duration(seconds: 1)); // finish the resize animation
   tester.pumpWidget(widgetBuilder(), const Duration(seconds: 1)); // dismiss
 }
 
+class Test1215DismissableComponent extends StatelessComponent {
+  Test1215DismissableComponent(this.text);
+  final String text;
+  Widget build(BuildContext context) {
+    return new Dismissable(
+      child: new AspectRatio(
+        aspectRatio: 1.0,
+        child: new Text(this.text)
+      )
+    );
+  }
+}
+
 void main() {
   test('Horizontal drag triggers dismiss scrollDirection=vertical', () {
     testWidgets((WidgetTester tester) {
@@ -230,4 +252,31 @@ void main() {
       tester.pumpWidget(widgetBuilder());
     });
   });
+
+  // This one is for
+  // https://github.com/flutter/engine/issues/1215
+  test('dismissing bottom then top (smoketest)', () {
+    testWidgets((WidgetTester tester) {
+      tester.pumpWidget(new Center(
+        child: new Container(
+          width: 100.0,
+          height: 1000.0,
+          child: new Column([
+            new Test1215DismissableComponent('1'),
+            new Test1215DismissableComponent('2')
+          ])
+        )
+      ));
+      expect(tester.findText('1'), isNotNull);
+      expect(tester.findText('2'), isNotNull);
+      dismissElement(tester, tester.findText('2'), gestureDirection: DismissDirection.right);
+      tester.pump(new Duration(seconds: 1));
+      expect(tester.findText('1'), isNotNull);
+      expect(tester.findText('2'), isNull);
+      dismissElement(tester, tester.findText('1'), gestureDirection: DismissDirection.right);
+      tester.pump(new Duration(seconds: 1));
+      expect(tester.findText('1'), isNull);
+      expect(tester.findText('2'), isNull);
+    });
+  });
 }

packages/unit/test/widget/draggable_test.dart

@@ -13,9 +13,9 @@ void main() {
 
       tester.pumpWidget(new Navigator(
         routes: {
-          '/': (NavigatorState navigator, Route route) { return new Column([
+          '/': (RouteArguments args) { return new Column([
               new Draggable(
-                navigator: navigator,
+                navigator: args.navigator,
                 data: 1,
                 child: new Text('Source'),
                 feedback: new Text('Dragging')

packages/unit/test/widget/fractionally_sized_box_test.dart

+import 'package:sky/rendering.dart';
 import 'package:sky/widgets.dart';
 import 'package:test/test.dart';
 
@@ -29,7 +30,8 @@ void main() {
         )
       ));
       expect(detectedSize, equals(const Size(50.0, 25.0)));
-      expect(inner.currentContext.findRenderObject().localToGlobal(Point.origin), equals(const Point(25.0, 37.5)));
+      RenderBox box = inner.currentContext.findRenderObject();
+      expect(box.localToGlobal(Point.origin), equals(const Point(25.0, 37.5)));
     });
   });
 }

packages/unit/test/widget/gesture_detector_test.dart

@@ -88,4 +88,38 @@ void main() {
       tester.pumpWidget(new Container());
     });
   });
+
+  test('Pan doesn\'t crash', () {
+    testWidgets((WidgetTester tester) {
+      bool didStartPan = false;
+      Offset panDelta;
+      bool didEndPan = false;
+
+      tester.pumpWidget(
+        new GestureDetector(
+          onPanStart: () {
+            didStartPan = true;
+          },
+          onPanUpdate: (Offset delta) {
+            panDelta = delta;
+          },
+          onPanEnd: (_) {
+            didEndPan = true;
+          },
+          child: new Container()
+        )
+      );
+
+      expect(didStartPan, isFalse);
+      expect(panDelta, isNull);
+      expect(didEndPan, isFalse);
+
+      tester.scrollAt(new Point(10.0, 10.0), new Offset(20.0, 30.0));
+
+      expect(didStartPan, isTrue);
+      expect(panDelta.dx, 20.0);
+      expect(panDelta.dy, 30.0);
+      expect(didEndPan, isTrue);
+    });
+  });
 }

packages/unit/test/widget/navigator_test.dart

@@ -49,8 +49,8 @@ void main() {
   test('Can navigator navigate to and from a stateful component', () {
     testWidgets((WidgetTester tester) {
       final Map<String, RouteBuilder> routes = <String, RouteBuilder>{
-        '/': (navigator, route) => new FirstComponent(navigator),
-        '/second': (navigator, route) => new SecondComponent(navigator),
+        '/': (RouteArguments args) => new FirstComponent(args.navigator),
+        '/second': (RouteArguments args) => new SecondComponent(args.navigator),
       };
 
       tester.pumpWidget(new Navigator(routes: routes));

packages/unit/test/widget/shader_mask_test.dart

+import 'dart:sky' as sky;
+
+import 'package:sky/painting.dart';
+import 'package:sky/widgets.dart';
+import 'package:test/test.dart';
+
+import 'widget_tester.dart';
+
+sky.Shader createShader(Rect bounds) {
+  return new LinearGradient(
+      begin: Point.origin,
+      end: new Point(0.0, bounds.height),
+      colors: [const Color(0x00FFFFFF), const Color(0xFFFFFFFF)],
+      stops: [0.1, 0.35]
+  )
+  .createShader();
+}
+
+
+void main() {
+  test('Can be constructed', () {
+    testWidgets((WidgetTester tester) {
+      Widget child = new Container(width: 100.0, height: 100.0);
+      tester.pumpWidget(new ShaderMask(child: child, shaderCallback: createShader));
+    });
+  });
+}

packages/unit/test/widget/widget_tester.dart

@@ -145,7 +145,10 @@ class WidgetTester {
   }
 
   void scroll(Element element, Offset offset, { int pointer: 1 }) {
-    Point startLocation = getCenter(element);
+    scrollAt(getCenter(element), offset, pointer: pointer);
+  }
+
+  void scrollAt(Point startLocation, Offset offset, { int pointer: 1 }) {
     Point endLocation = startLocation + offset;
     TestPointer p = new TestPointer(pointer);
     // Events for the entire press-drag-release gesture are dispatched