Merge pull request #902 from Hixie/bindings

Refactor bindings.

examples/rendering/align_items.dart

@@ -42,5 +42,5 @@ void main() {
     child: new RenderPadding(child: table, padding: new EdgeDims.symmetric(vertical: 50.0))
   );
 
-  new FlutterBinding(root: root);
+  new RenderingFlutterBinding(root: root);
 }

examples/rendering/baseline.dart

@@ -87,5 +87,5 @@ void main() {
     direction: FlexDirection.vertical,
     alignItems: FlexAlignItems.stretch
   );
-  new FlutterBinding(root: root);
+  new RenderingFlutterBinding(root: root);
 }

examples/rendering/borders.dart

@@ -73,5 +73,5 @@ void main() {
     ],
     direction: FlexDirection.vertical
   );
-  new FlutterBinding(root: root);
+  new RenderingFlutterBinding(root: root);
 }

examples/rendering/flex.dart

@@ -53,5 +53,5 @@ RenderBox buildFlexExample() {
 }
 
 void main() {
-  new FlutterBinding(root: buildFlexExample());
+  new RenderingFlutterBinding(root: buildFlexExample());
 }

examples/rendering/interactive_flex.dart

@@ -6,6 +6,7 @@ import 'dart:ui' as ui;
 import 'dart:math' as math;
 import 'dart:typed_data';
 
+import 'package:flutter/scheduler.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter/rendering.dart';
 import 'package:mojo/bindings.dart' as bindings;
@@ -37,13 +38,20 @@ class RenderImageGrow extends RenderImage {
 
 RenderImageGrow image;
 
-void handlePopRoute() {
+class DemoBinding extends BindingBase with Scheduler, Renderer {
+  DemoBinding({ RenderBox root }) {
+    renderView.child = root;
+    ui.window.onPopRoute = handlePopRoute;
+    ui.window.onPointerPacket = handlePointerPacket;
+  }
+
+  void handlePopRoute() {
     activity.finishCurrentActivity();
-}
+  }
 
-final Map<int, Touch> touches = <int, Touch>{};
+  final Map<int, Touch> touches = <int, Touch>{};
 
-void handlePointerPacket(ByteData serializedPacket) {
+  void handlePointerPacket(ByteData serializedPacket) {
     bindings.Message message = new bindings.Message(
       serializedPacket,
       <core.MojoHandle>[],
@@ -51,12 +59,12 @@ void handlePointerPacket(ByteData serializedPacket) {
       0
     );
     PointerPacket packet = PointerPacket.deserialize(message);
-
     for (Pointer pointer in packet.pointers) {
       if (pointer.type == PointerType.MOVE)
         image.growth = math.max(0.0, image.growth + pointer.x - touches[pointer.pointer].x);
       touches[pointer.pointer] = new Touch(pointer.x, pointer.y);
     }
+  }
 }
 
 void main() {
@@ -74,7 +82,7 @@ void main() {
 
   // Resizeable image
   image = new RenderImageGrow(null, new Size(100.0, null));
-  imageCache.load("https://www.dartlang.org/logos/dart-logo.png").first.then((ui.Image dartLogo) {
+  imageCache.load("http://flutter.io/favicon.ico").first.then((ui.Image dartLogo) {
     image.image = dartLogo;
   });
 
@@ -114,7 +122,5 @@ Pancetta meatball tongue tenderloin rump tail jowl boudin.""";
   );
 
   updateTaskDescription('Interactive Flex', topColor);
-  new FlutterBinding(root: root);
-  ui.window.onPopRoute = handlePopRoute;
-  ui.window.onPointerPacket = handlePointerPacket;
+  new DemoBinding(root: root);
 }

examples/rendering/justify_content.dart

@@ -37,5 +37,5 @@ void main() {
     child: new RenderPadding(child: table, padding: new EdgeDims.symmetric(vertical: 50.0))
   );
 
-  new FlutterBinding(root: root);
+  new RenderingFlutterBinding(root: root);
 }

examples/rendering/render_grid.dart

@@ -23,4 +23,4 @@ RenderBox buildGridExample() {
   return new RenderGrid(children: children, maxChildExtent: 100.0);
 }
 
-main() => new FlutterBinding(root: buildGridExample());
+main() => new RenderingFlutterBinding(root: buildGridExample());

examples/rendering/render_paragraph.dart

@@ -40,5 +40,5 @@ Pancetta meatball tongue tenderloin rump tail jowl boudin.""";
   childParentData = child.parentData;
   childParentData.flex = 1;
 
-  new FlutterBinding(root: root);
+  new RenderingFlutterBinding(root: root);
 }

examples/rendering/sector_layout.dart

@@ -18,5 +18,5 @@ RenderBox buildSectorExample() {
 }
 
 void main() {
-  new FlutterBinding(root: buildSectorExample());
+  new RenderingFlutterBinding(root: buildSectorExample());
 }

examples/rendering/shadowed_box.dart

@@ -18,7 +18,7 @@ void main() {
   var paddedBox = new RenderPadding(
     padding: const EdgeDims.all(50.0),
     child: coloredBox);
-  new FlutterBinding(root: new RenderDecoratedBox(
+  new RenderingFlutterBinding(root: new RenderDecoratedBox(
     decoration: const BoxDecoration(
       backgroundColor: const Color(0xFFFFFFFF)
     ),

examples/rendering/simple_autolayout.dart

@@ -59,5 +59,5 @@ void main() {
     (p4.verticalCenter == p2.height / al.cm(2.0)) as al.Constraint,
   ]);
 
-  new FlutterBinding(root: root);
+  new RenderingFlutterBinding(root: root);
 }

examples/rendering/spinning_flex.dart

@@ -5,7 +5,6 @@
 import 'dart:ui' as ui;
 
 import 'package:flutter/rendering.dart';
-import 'package:flutter/scheduler.dart';
 
 import 'lib/solid_color_box.dart';
 
@@ -30,9 +29,8 @@ void main() {
 
   RenderPadding root = new RenderPadding(padding: new EdgeDims.all(20.0), child: transformBox);
 
-  new FlutterBinding(root: root);
-
-  scheduler.addPersistentFrameCallback(rotate);
+  new RenderingFlutterBinding(root: root)
+    ..addPersistentFrameCallback(rotate);
 }
 
 void rotate(Duration timeStamp) {

examples/rendering/touch_demo.dart

@@ -77,5 +77,5 @@ void main() {
   final StackParentData paragraphParentData = paragraph.parentData;
   paragraphParentData..top = 40.0
                      ..left = 20.0;
-  new FlutterBinding(root: stack);
+  new RenderingFlutterBinding(root: stack);
 }

examples/rendering/transform.dart

@@ -24,5 +24,5 @@ void main() {
 
   RenderFlex flex = new RenderFlex();
   flex.add(spin);
-  new FlutterBinding(root: flex);
+  new RenderingFlutterBinding(root: flex);
 }

examples/widgets/spinning_mixed.dart

@@ -6,7 +6,6 @@ import 'dart:ui' as ui;
 
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/scheduler.dart';
 
 import 'package:flutter_rendering_examples/solid_color_box.dart';
 
@@ -84,11 +83,6 @@ void rotate(Duration timeStamp) {
 }
 
 void main() {
-  // Because we're going to use Widgets, we want to ensure we're using a
-  // WidgetFlutterBinding rather than some other kind of binding (e.g. a
-  // straight rendering library FlutterBinding).
-  WidgetFlutterBinding.ensureInitialized();
-
   RenderProxyBox proxy = new RenderProxyBox();
   attachWidgetTreeToRenderTree(proxy);
 
@@ -100,6 +94,7 @@ void main() {
   transformBox = new RenderTransform(child: flexRoot, transform: new Matrix4.identity());
   RenderPadding root = new RenderPadding(padding: new EdgeDims.all(80.0), child: transformBox);
 
-  FlutterBinding.instance.renderView.child = root;
-  scheduler.addPersistentFrameCallback(rotate);
+  WidgetFlutterBinding.ensureInitialized()
+   ..renderView.child = root
+   ..addPersistentFrameCallback(rotate);
 }

packages/flutter/lib/gestures.dart

@@ -6,9 +6,12 @@
 library gestures;
 
 export 'src/gestures/arena.dart';
+export 'src/gestures/binding.dart';
 export 'src/gestures/constants.dart';
+export 'src/gestures/converter.dart';
 export 'src/gestures/drag.dart';
 export 'src/gestures/events.dart';
+export 'src/gestures/hit_test.dart';
 export 'src/gestures/long_press.dart';
 export 'src/gestures/lsq_solver.dart';
 export 'src/gestures/multitap.dart';

packages/flutter/lib/rendering.dart

@@ -16,7 +16,6 @@ export 'src/rendering/editable_paragraph.dart';
 export 'src/rendering/error.dart';
 export 'src/rendering/flex.dart';
 export 'src/rendering/grid.dart';
-export 'src/rendering/hit_test.dart';
 export 'src/rendering/image.dart';
 export 'src/rendering/layer.dart';
 export 'src/rendering/node.dart';

packages/flutter/lib/services.dart

@@ -13,6 +13,7 @@ library services;
 
 export 'src/services/activity.dart';
 export 'src/services/asset_bundle.dart';
+export 'src/services/binding.dart';
 export 'src/services/fetch.dart';
 export 'src/services/image_cache.dart';
 export 'src/services/image_decoder.dart';

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

@@ -40,7 +40,7 @@ class Ticker {
     _startTime = null;
 
     if (_animationId != null) {
-      scheduler.cancelFrameCallbackWithId(_animationId);
+      Scheduler.instance.cancelFrameCallbackWithId(_animationId);
       _animationId = null;
     }
 
@@ -74,6 +74,6 @@ class Ticker {
   void _scheduleTick() {
     assert(isTicking);
     assert(_animationId == null);
-    _animationId = scheduler.scheduleFrameCallback(_tick);
+    _animationId = Scheduler.instance.scheduleFrameCallback(_tick);
   }
 }

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

@@ -64,8 +64,6 @@ class _GestureArenaState {
 class GestureArena {
   final Map<Object, _GestureArenaState> _arenas = new Map<Object, _GestureArenaState>();
 
-  static final GestureArena instance = new GestureArena();
-
   GestureArenaEntry add(Object key, GestureArenaMember member) {
     _GestureArenaState state = _arenas.putIfAbsent(key, () => new _GestureArenaState());
     state.add(member);

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

@@ -0,0 +1,94 @@
+// 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 'dart:typed_data';
+import 'dart:ui' as ui;
+
+import 'package:flutter/services.dart';
+import 'package:mojo/bindings.dart' as mojo_bindings;
+import 'package:mojo/core.dart' as mojo_core;
+import 'package:sky_services/pointer/pointer.mojom.dart';
+
+import 'arena.dart';
+import 'converter.dart';
+import 'events.dart';
+import 'hit_test.dart';
+import 'pointer_router.dart';
+
+abstract class Pointerer extends BindingBase implements HitTestTarget, HitTestable {
+
+  void initInstances() {
+    super.initInstances();
+    _instance = this;
+    ui.window.onPointerPacket = _handlePointerPacket;
+  }
+
+  static Pointerer _instance;
+  static Pointerer get instance => _instance;
+
+  void _handlePointerPacket(ByteData serializedPacket) {
+    final mojo_bindings.Message message = new mojo_bindings.Message(
+      serializedPacket,
+      <mojo_core.MojoHandle>[],
+      serializedPacket.lengthInBytes,
+      0
+    );
+    final PointerPacket packet = PointerPacket.deserialize(message);
+    for (PointerEvent event in PointerEventConverter.expand(packet.pointers))
+      _handlePointerEvent(event);
+  }
+
+  /// A router that routes all pointer events received from the engine.
+  final PointerRouter pointerRouter = new PointerRouter();
+
+  /// The gesture arenas used for disambiguating the meaning of sequences of
+  /// pointer events.
+  final GestureArena gestureArena = new GestureArena();
+
+  /// State for all pointers which are currently down.
+  ///
+  /// The state of hovering pointers is not tracked because that would require
+  /// hit-testing on every frame.
+  Map<int, HitTestResult> _hitTests = <int, HitTestResult>{};
+
+  void _handlePointerEvent(PointerEvent event) {
+    if (event is PointerDownEvent) {
+      assert(!_hitTests.containsKey(event.pointer));
+      HitTestResult result = new HitTestResult();
+      hitTest(result, event.position);
+      _hitTests[event.pointer] = result;
+    } else if (event is! PointerUpEvent) {
+      assert(event.down == _hitTests.containsKey(event.pointer));
+      if (!event.down)
+        return; // we currently ignore add, remove, and hover move events
+    }
+    assert(_hitTests[event.pointer] != null);
+    dispatchEvent(event, _hitTests[event.pointer]);
+    if (event is PointerUpEvent) {
+      assert(_hitTests.containsKey(event.pointer));
+      _hitTests.remove(event.pointer);
+    }
+  }
+
+  /// Determine which [HitTestTarget] objects are located at a given position.
+  void hitTest(HitTestResult result, Point position) {
+    result.add(new HitTestEntry(this));
+  }
+
+  /// Dispatch the given event to the path of the given hit test result
+  void dispatchEvent(PointerEvent event, HitTestResult result) {
+    assert(result != null);
+    for (HitTestEntry entry in result.path)
+      entry.target.handleEvent(event, entry);
+  }
+
+  void handleEvent(PointerEvent event, HitTestEntry entry) {
+    pointerRouter.route(event);
+    if (event is PointerDownEvent) {
+      gestureArena.close(event.pointer);
+    } else if (event is PointerUpEvent) {
+      gestureArena.sweep(event.pointer);
+    }
+  }
+}

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

@@ -0,0 +1,183 @@
+// 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_services/pointer/pointer.mojom.dart';
+
+import 'events.dart';
+
+class _PointerState {
+  _PointerState(this.lastPosition);
+
+  int get pointer => _pointer; // The identifier used in PointerEvent objects.
+  int _pointer;
+  static int _pointerCount = 0;
+  void startNewPointer() {
+    _pointerCount += 1;
+    _pointer = _pointerCount;
+  }
+
+  bool get down => _down;
+  bool _down = false;
+  void setDown() {
+    assert(!_down);
+    _down = true;
+  }
+  void setUp() {
+    assert(_down);
+    _down = false;
+  }
+
+  Point lastPosition;
+}
+
+class PointerEventConverter {
+  // Map from platform pointer identifiers to PointerEvent pointer identifiers.
+  static Map<int, _PointerState> _pointers = <int, _PointerState>{};
+
+  static Iterable<PointerEvent> expand(Iterable<Pointer> packet) sync* {
+    for (Pointer datum in packet) {
+      Point position = new Point(datum.x, datum.y);
+      Duration timeStamp = new Duration(microseconds: datum.timeStamp);
+      assert(_pointerKindMap.containsKey(datum.kind));
+      PointerDeviceKind kind = _pointerKindMap[datum.kind];
+      switch (datum.type) {
+        case PointerType.DOWN:
+          assert(!_pointers.containsKey(datum.pointer));
+          _PointerState state = _pointers.putIfAbsent(
+            datum.pointer,
+            () => new _PointerState(position)
+          );
+          assert(state.lastPosition == position);
+          state.startNewPointer();
+          state.setDown();
+          yield new PointerAddedEvent(
+            timeStamp: timeStamp,
+            pointer: state.pointer,
+            kind: kind,
+            position: position,
+            obscured: datum.obscured,
+            pressureMin: datum.pressureMin,
+            pressureMax: datum.pressureMax,
+            distance: datum.distance,
+            distanceMax: datum.distanceMax,
+            radiusMin: datum.radiusMin,
+            radiusMax: datum.radiusMax,
+            orientation: datum.orientation,
+            tilt: datum.tilt
+          );
+          yield new PointerDownEvent(
+            timeStamp: timeStamp,
+            pointer: state.pointer,
+            kind: kind,
+            position: position,
+            obscured: datum.obscured,
+            pressure: datum.pressure,
+            pressureMin: datum.pressureMin,
+            pressureMax: datum.pressureMax,
+            distanceMax: datum.distanceMax,
+            radiusMajor: datum.radiusMajor,
+            radiusMinor: datum.radiusMajor,
+            radiusMin: datum.radiusMin,
+            radiusMax: datum.radiusMax,
+            orientation: datum.orientation,
+            tilt: datum.tilt
+          );
+          break;
+        case PointerType.MOVE:
+          // If the service starts supporting hover pointers, then it must also
+          // start sending us ADDED and REMOVED data points.
+          // See also: https://github.com/flutter/flutter/issues/720
+          assert(_pointers.containsKey(datum.pointer));
+          _PointerState state = _pointers[datum.pointer];
+          assert(state.down);
+          Offset offset = position - state.lastPosition;
+          state.lastPosition = position;
+          yield new PointerMoveEvent(
+            timeStamp: timeStamp,
+            pointer: state.pointer,
+            kind: kind,
+            position: position,
+            delta: offset,
+            down: state.down,
+            obscured: datum.obscured,
+            pressure: datum.pressure,
+            pressureMin: datum.pressureMin,
+            pressureMax: datum.pressureMax,
+            distance: datum.distance,
+            distanceMax: datum.distanceMax,
+            radiusMajor: datum.radiusMajor,
+            radiusMinor: datum.radiusMajor,
+            radiusMin: datum.radiusMin,
+            radiusMax: datum.radiusMax,
+            orientation: datum.orientation,
+            tilt: datum.tilt
+          );
+          break;
+        case PointerType.UP:
+        case PointerType.CANCEL:
+          assert(_pointers.containsKey(datum.pointer));
+          _PointerState state = _pointers[datum.pointer];
+          assert(state.down);
+          assert(position == state.lastPosition);
+          state.setUp();
+          if (datum.type == PointerType.UP) {
+            yield new PointerUpEvent(
+              timeStamp: timeStamp,
+              pointer: state.pointer,
+              kind: kind,
+              position: position,
+              obscured: datum.obscured,
+              pressureMax: datum.pressureMax,
+              distance: datum.distance,
+              distanceMax: datum.distanceMax,
+              radiusMin: datum.radiusMin,
+              radiusMax: datum.radiusMax,
+              orientation: datum.orientation,
+              tilt: datum.tilt
+            );
+          } else {
+            yield new PointerCancelEvent(
+              timeStamp: timeStamp,
+              pointer: state.pointer,
+              kind: kind,
+              position: position,
+              obscured: datum.obscured,
+              pressureMin: datum.pressureMin,
+              pressureMax: datum.pressureMax,
+              distance: datum.distance,
+              distanceMax: datum.distanceMax,
+              radiusMin: datum.radiusMin,
+              radiusMax: datum.radiusMax,
+              orientation: datum.orientation,
+              tilt: datum.tilt
+            );
+          }
+          yield new PointerRemovedEvent(
+            timeStamp: timeStamp,
+            pointer: state.pointer,
+            kind: kind,
+            obscured: datum.obscured,
+            pressureMin: datum.pressureMin,
+            pressureMax: datum.pressureMax,
+            distanceMax: datum.distanceMax,
+            radiusMin: datum.radiusMin,
+            radiusMax: datum.radiusMax
+          );
+          _pointers.remove(datum.pointer);
+          break;
+        default:
+          // TODO(ianh): once https://github.com/flutter/flutter/issues/720 is
+          // done, add real support for PointerAddedEvent and PointerRemovedEvent
+          assert(false);
+      }
+    }
+  }
+
+  static const Map<PointerKind, PointerDeviceKind> _pointerKindMap = const <PointerKind, PointerDeviceKind>{
+    PointerKind.TOUCH: PointerDeviceKind.touch,
+    PointerKind.MOUSE: PointerDeviceKind.mouse,
+    PointerKind.STYLUS: PointerDeviceKind.stylus,
+    PointerKind.INVERTED_STYLUS: PointerDeviceKind.invertedStylus,
+  };
+}

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

@@ -32,8 +32,16 @@ bool _isFlingGesture(Offset velocity) {
 }
 
 abstract class _DragGestureRecognizer<T extends dynamic> extends OneSequenceGestureRecognizer {
-  _DragGestureRecognizer({ PointerRouter router, this.onStart, this.onUpdate, this.onEnd })
-    : super(router: router);
+  _DragGestureRecognizer({
+    PointerRouter router,
+    GestureArena gestureArena,
+    this.onStart,
+    this.onUpdate,
+    this.onEnd
+  }) : super(
+    router: router,
+    gestureArena: gestureArena
+  );
 
   GestureDragStartCallback onStart;
   _GesturePolymorphicUpdateCallback<T> onUpdate;
@@ -120,10 +128,17 @@ abstract class _DragGestureRecognizer<T extends dynamic> extends OneSequenceGest
 class VerticalDragGestureRecognizer extends _DragGestureRecognizer<double> {
   VerticalDragGestureRecognizer({
     PointerRouter router,
+    GestureArena gestureArena,
     GestureDragStartCallback onStart,
     GestureDragUpdateCallback onUpdate,
     GestureDragEndCallback onEnd
-  }) : super(router: router, onStart: onStart, onUpdate: onUpdate, onEnd: onEnd);
+  }) : super(
+    router: router,
+    gestureArena: gestureArena,
+    onStart: onStart,
+    onUpdate: onUpdate,
+    onEnd: onEnd
+  );
 
   double get _initialPendingDragDelta => 0.0;
   double _getDragDelta(PointerEvent event) => event.delta.dy;
@@ -133,10 +148,17 @@ class VerticalDragGestureRecognizer extends _DragGestureRecognizer<double> {
 class HorizontalDragGestureRecognizer extends _DragGestureRecognizer<double> {
   HorizontalDragGestureRecognizer({
     PointerRouter router,
+    GestureArena gestureArena,
     GestureDragStartCallback onStart,
     GestureDragUpdateCallback onUpdate,
     GestureDragEndCallback onEnd
-  }) : super(router: router, onStart: onStart, onUpdate: onUpdate, onEnd: onEnd);
+  }) : super(
+    router: router,
+    gestureArena: gestureArena,
+    onStart: onStart,
+    onUpdate: onUpdate,
+    onEnd: onEnd
+  );
 
   double get _initialPendingDragDelta => 0.0;
   double _getDragDelta(PointerEvent event) => event.delta.dx;
@@ -146,10 +168,17 @@ class HorizontalDragGestureRecognizer extends _DragGestureRecognizer<double> {
 class PanGestureRecognizer extends _DragGestureRecognizer<Offset> {
   PanGestureRecognizer({
     PointerRouter router,
+    GestureArena gestureArena,
     GesturePanStartCallback onStart,
     GesturePanUpdateCallback onUpdate,
     GesturePanEndCallback onEnd
-  }) : super(router: router, onStart: onStart, onUpdate: onUpdate, onEnd: onEnd);
+  }) : super(
+    router: router,
+    gestureArena: gestureArena,
+    onStart: onStart,
+    onUpdate: onUpdate,
+    onEnd: onEnd
+  );
 
   Offset get _initialPendingDragDelta => Offset.zero;
   Offset _getDragDelta(PointerEvent event) => event.delta;

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

@@ -2,7 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/gestures.dart';
+import 'events.dart';
+
+/// An object that can hit-test pointers.
+abstract class HitTestable {
+  void hitTest(HitTestResult result, Point position);
+}
 
 /// An object that can handle events.
 abstract class HitTestTarget {

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

@@ -11,8 +11,15 @@ import 'recognizer.dart';
 typedef void GestureLongPressCallback();
 
 class LongPressGestureRecognizer extends PrimaryPointerGestureRecognizer {
-  LongPressGestureRecognizer({ PointerRouter router, this.onLongPress })
-    : super(router: router, deadline: kLongPressTimeout);
+  LongPressGestureRecognizer({
+    PointerRouter router,
+    GestureArena gestureArena,
+    this.onLongPress
+  }) : super(
+    router: router,
+    gestureArena: gestureArena,
+    deadline: kLongPressTimeout
+  );
 
   GestureLongPressCallback onLongPress;
 

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

@@ -58,9 +58,12 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
 
   DoubleTapGestureRecognizer({
     PointerRouter router,
+    GestureArena gestureArena,
     this.onDoubleTap
-  }) : _router = router {
+  }) : _router = router,
+       _gestureArena = gestureArena {
     assert(router != null);
+    assert(gestureArena != null);
   }
 
   // Implementation notes:
@@ -84,6 +87,7 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
   // - The gesture arena decides we have been rejected wholesale
 
   PointerRouter _router;
+  GestureArena _gestureArena;
   GestureDoubleTapCallback onDoubleTap;
 
   Timer _doubleTapTimer;
@@ -98,7 +102,7 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
     _stopDoubleTapTimer();
     _TapTracker tracker = new _TapTracker(
       event: event,
-      entry: GestureArena.instance.add(event.pointer, this)
+      entry: _gestureArena.add(event.pointer, this)
     );
     _trackers[event.pointer] = tracker;
     tracker.startTrackingPointer(_router, handleEvent);
@@ -149,6 +153,7 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
   void dispose() {
     _reset();
     _router = null;
+    _gestureArena = null;
   }
 
   void _reset() {
@@ -159,14 +164,14 @@ class DoubleTapGestureRecognizer extends GestureRecognizer {
       _TapTracker tracker = _firstTap;
       _firstTap = null;
       _reject(tracker);
-      GestureArena.instance.release(tracker.pointer);
+      _gestureArena.release(tracker.pointer);
     }
     _clearTrackers();
   }
 
   void _registerFirstTap(_TapTracker tracker) {
     _startDoubleTapTimer();
-    GestureArena.instance.hold(tracker.pointer);
+    _gestureArena.hold(tracker.pointer);
     // Note, order is important below in order for the clear -> reject logic to
     // work properly.
     _freezeTracker(tracker);
@@ -226,7 +231,10 @@ class _TapGesture extends _TapTracker {
     Duration longTapDelay
   }) : gestureRecognizer = gestureRecognizer,
        _lastPosition = event.position,
-       super(event: event, entry: GestureArena.instance.add(event.pointer, gestureRecognizer)) {
+       super(
+    event: event,
+    entry: gestureRecognizer._gestureArena.add(event.pointer, gestureRecognizer)
+  ) {
     startTrackingPointer(gestureRecognizer.router, handleEvent);
     if (longTapDelay > Duration.ZERO) {
       _timer = new Timer(longTapDelay, () {
@@ -299,18 +307,23 @@ class _TapGesture extends _TapTracker {
 class MultiTapGestureRecognizer extends GestureRecognizer {
   MultiTapGestureRecognizer({
     PointerRouter router,
+    GestureArena gestureArena,
     this.onTapDown,
     this.onTapUp,
     this.onTap,
     this.onTapCancel,
     this.longTapDelay: Duration.ZERO,
     this.onLongTapDown
-  }) : _router = router {
+  }) : _router = router,
+       _gestureArena = gestureArena {
     assert(router != null);
+    assert(gestureArena != null);
   }
 
   PointerRouter get router => _router;
   PointerRouter _router;
+  GestureArena get gestureArena => _gestureArena;
+  GestureArena _gestureArena;
   GestureMultiTapDownCallback onTapDown;
   GestureMultiTapUpCallback onTapUp;
   GestureMultiTapCallback onTap;
@@ -369,6 +382,7 @@ class MultiTapGestureRecognizer extends GestureRecognizer {
     // Rejection of each gesture should cause it to be removed from our map
     assert(_gestureMap.isEmpty);
     _router = null;
+    _gestureArena = null;
   }
 
 }

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

@@ -30,11 +30,17 @@ abstract class GestureRecognizer extends GestureArenaMember {
 }
 
 abstract class OneSequenceGestureRecognizer extends GestureRecognizer {
-  OneSequenceGestureRecognizer({ PointerRouter router }) : _router = router {
+  OneSequenceGestureRecognizer({
+    PointerRouter router,
+    GestureArena gestureArena
+  }) : _router = router,
+       _gestureArena = gestureArena {
     assert(_router != null);
+    assert(_gestureArena != null);
   }
 
   PointerRouter _router;
+  GestureArena _gestureArena;
 
   final List<GestureArenaEntry> _entries = <GestureArenaEntry>[];
   final Set<int> _trackedPointers = new Set<int>();
@@ -58,12 +64,13 @@ abstract class OneSequenceGestureRecognizer extends GestureRecognizer {
     _trackedPointers.clear();
     assert(_entries.isEmpty);
     _router = null;
+    _gestureArena = null;
   }
 
   void startTrackingPointer(int pointer) {
     _router.addRoute(pointer, handleEvent);
     _trackedPointers.add(pointer);
-    _entries.add(GestureArena.instance.add(pointer, this));
+    _entries.add(_gestureArena.add(pointer, this));
   }
 
   void stopTrackingPointer(int pointer) {
@@ -87,8 +94,14 @@ enum GestureRecognizerState {
 }
 
 abstract class PrimaryPointerGestureRecognizer extends OneSequenceGestureRecognizer {
-  PrimaryPointerGestureRecognizer({ PointerRouter router, this.deadline })
-    : super(router: router);
+  PrimaryPointerGestureRecognizer({
+    PointerRouter router,
+    GestureArena gestureArena,
+    this.deadline
+  }) : super(
+    router: router,
+    gestureArena: gestureArena
+  );
 
   final Duration deadline;
 

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

@@ -19,8 +19,16 @@ typedef void GestureScaleUpdateCallback(double scale, Point focalPoint);
 typedef void GestureScaleEndCallback();
 
 class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
-  ScaleGestureRecognizer({ PointerRouter router, this.onStart, this.onUpdate, this.onEnd })
-    : super(router: router);
+  ScaleGestureRecognizer({
+    PointerRouter router,
+    GestureArena gestureArena,
+    this.onStart,
+    this.onUpdate,
+    this.onEnd
+  }) : super(
+    router: router,
+    gestureArena: gestureArena
+  );
 
   GestureScaleStartCallback onStart;
   GestureScaleUpdateCallback onUpdate;

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

@@ -19,11 +19,16 @@ typedef void GestureTapCancelCallback();
 class TapGestureRecognizer extends PrimaryPointerGestureRecognizer {
   TapGestureRecognizer({
     PointerRouter router,
+    GestureArena gestureArena,
     this.onTapDown,
     this.onTapUp,
     this.onTap,
     this.onTapCancel
-  }) : super(router: router, deadline: kPressTimeout);
+  }) : super(
+    router: router,
+    gestureArena: gestureArena,
+    deadline: kPressTimeout
+  );
 
   GestureTapDownCallback onTapDown;
   GestureTapDownCallback onTapUp;

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

@@ -74,11 +74,11 @@ class _MaterialAppState extends State<MaterialApp> implements BindingObserver {
     _navigator = new GlobalObjectKey(this);
     _size = ui.window.size;
     didChangeLocale(ui.window.locale);
-    FlutterBinding.instance.addObserver(this);
+    WidgetFlutterBinding.instance.addObserver(this);
   }
 
   void dispose() {
-    FlutterBinding.instance.removeObserver(this);
+    WidgetFlutterBinding.instance.removeObserver(this);
     super.dispose();
   }
 

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

@@ -86,7 +86,7 @@ class _RenderSlider extends RenderConstrainedBox {
        _activeColor = activeColor,
         super(additionalConstraints: const BoxConstraints.tightFor(width: _kTrackWidth + 2 * _kReactionRadius, height: 2 * _kReactionRadius)) {
     assert(value != null && value >= 0.0 && value <= 1.0);
-    _drag = new HorizontalDragGestureRecognizer(router: FlutterBinding.instance.pointerRouter)
+    _drag = new HorizontalDragGestureRecognizer(router: Pointerer.instance.pointerRouter, gestureArena: Pointerer.instance.gestureArena)
       ..onStart = _handleDragStart
       ..onUpdate = _handleDragUpdate
       ..onEnd = _handleDragEnd;

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

@@ -115,7 +115,7 @@ class _RenderSwitch extends RenderToggleable {
    ) {
     _activeTrackColor = activeTrackColor;
     _inactiveTrackColor = inactiveTrackColor;
-    _drag = new HorizontalDragGestureRecognizer(router: FlutterBinding.instance.pointerRouter)
+    _drag = new HorizontalDragGestureRecognizer(router: Pointerer.instance.pointerRouter, gestureArena: Pointerer.instance.gestureArena)
       ..onStart = _handleDragStart
       ..onUpdate = _handleDragUpdate
       ..onEnd = _handleDragEnd;

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

@@ -29,7 +29,7 @@ abstract class RenderToggleable extends RenderConstrainedBox {
     assert(value != null);
     assert(activeColor != null);
     assert(inactiveColor != null);
-    _tap = new TapGestureRecognizer(router: FlutterBinding.instance.pointerRouter)
+    _tap = new TapGestureRecognizer(router: Pointerer.instance.pointerRouter, gestureArena: Pointerer.instance.gestureArena)
       ..onTapDown = _handleTapDown
       ..onTap = _handleTap
       ..onTapUp = _handleTapUp

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

@@ -420,6 +420,8 @@ void paintImage({
   double alignX,
   double alignY
 }) {
+  assert(canvas != null);
+  assert(image != null);
   Size outputSize = rect.size;
   Size inputSize = new Size(image.width.toDouble(), image.height.toDouble());
   Offset sliceBorder;

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

@@ -220,7 +220,7 @@ class RenderAutoLayout extends RenderBox
     // only indicates that the value has been flushed to the variable.
   }
 
-  bool hitTestChildren(HitTestResult result, {Point position}) {
+  bool hitTestChildren(HitTestResult result, { Point position }) {
     return defaultHitTestChildren(result, position: position);
   }
 

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

@@ -2,265 +2,64 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:typed_data';
 import 'dart:ui' as ui;
 
 import 'package:flutter/gestures.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:mojo/bindings.dart' as mojo_bindings;
-import 'package:mojo/core.dart' as mojo_core;
-import 'package:sky_services/pointer/pointer.mojom.dart';
+import 'package:flutter/services.dart';
 
 import 'box.dart';
 import 'debug.dart';
-import 'hit_test.dart';
 import 'object.dart';
 import 'view.dart';
 
-typedef void MetricListener(Size size);
-
-class _PointerState {
-  _PointerState(this.lastPosition);
-
-  int get pointer => _pointer; // The identifier used in PointerEvent objects.
-  int _pointer;
-  static int _pointerCount = 0;
-  void startNewPointer() {
-    _pointerCount += 1;
-    _pointer = _pointerCount;
-  }
-
-  bool get down => _down;
-  bool _down = false;
-  void setDown() {
-    assert(!_down);
-    _down = true;
-  }
-  void setUp() {
-    assert(_down);
-    _down = false;
-  }
-
-  Point lastPosition;
-}
-
-class _PointerEventConverter {
-  // Map from platform pointer identifiers to PointerEvent pointer identifiers.
-  static Map<int, _PointerState> _pointers = <int, _PointerState>{};
-
-  static Iterable<PointerEvent> expand(Iterable<Pointer> packet) sync* {
-    for (Pointer datum in packet) {
-      Point position = new Point(datum.x, datum.y);
-      Duration timeStamp = new Duration(microseconds: datum.timeStamp);
-      assert(_pointerKindMap.containsKey(datum.kind));
-      PointerDeviceKind kind = _pointerKindMap[datum.kind];
-      switch (datum.type) {
-        case PointerType.DOWN:
-          assert(!_pointers.containsKey(datum.pointer));
-          _PointerState state = _pointers.putIfAbsent(
-            datum.pointer,
-            () => new _PointerState(position)
-          );
-          assert(state.lastPosition == position);
-          state.startNewPointer();
-          state.setDown();
-          yield new PointerAddedEvent(
-            timeStamp: timeStamp,
-            pointer: state.pointer,
-            kind: kind,
-            position: position,
-            obscured: datum.obscured,
-            pressureMin: datum.pressureMin,
-            pressureMax: datum.pressureMax,
-            distance: datum.distance,
-            distanceMax: datum.distanceMax,
-            radiusMin: datum.radiusMin,
-            radiusMax: datum.radiusMax,
-            orientation: datum.orientation,
-            tilt: datum.tilt
-          );
-          yield new PointerDownEvent(
-            timeStamp: timeStamp,
-            pointer: state.pointer,
-            kind: kind,
-            position: position,
-            obscured: datum.obscured,
-            pressure: datum.pressure,
-            pressureMin: datum.pressureMin,
-            pressureMax: datum.pressureMax,
-            distanceMax: datum.distanceMax,
-            radiusMajor: datum.radiusMajor,
-            radiusMinor: datum.radiusMajor,
-            radiusMin: datum.radiusMin,
-            radiusMax: datum.radiusMax,
-            orientation: datum.orientation,
-            tilt: datum.tilt
-          );
-          break;
-        case PointerType.MOVE:
-          // If the service starts supporting hover pointers, then it must also
-          // start sending us ADDED and REMOVED data points.
-          // See also: https://github.com/flutter/flutter/issues/720
-          assert(_pointers.containsKey(datum.pointer));
-          _PointerState state = _pointers[datum.pointer];
-          assert(state.down);
-          Offset offset = position - state.lastPosition;
-          state.lastPosition = position;
-          yield new PointerMoveEvent(
-            timeStamp: timeStamp,
-            pointer: state.pointer,
-            kind: kind,
-            position: position,
-            delta: offset,
-            down: state.down,
-            obscured: datum.obscured,
-            pressure: datum.pressure,
-            pressureMin: datum.pressureMin,
-            pressureMax: datum.pressureMax,
-            distance: datum.distance,
-            distanceMax: datum.distanceMax,
-            radiusMajor: datum.radiusMajor,
-            radiusMinor: datum.radiusMajor,
-            radiusMin: datum.radiusMin,
-            radiusMax: datum.radiusMax,
-            orientation: datum.orientation,
-            tilt: datum.tilt
-          );
-          break;
-        case PointerType.UP:
-        case PointerType.CANCEL:
-          assert(_pointers.containsKey(datum.pointer));
-          _PointerState state = _pointers[datum.pointer];
-          assert(state.down);
-          assert(position == state.lastPosition);
-          state.setUp();
-          if (datum.type == PointerType.UP) {
-            yield new PointerUpEvent(
-              timeStamp: timeStamp,
-              pointer: state.pointer,
-              kind: kind,
-              position: position,
-              obscured: datum.obscured,
-              pressureMax: datum.pressureMax,
-              distance: datum.distance,
-              distanceMax: datum.distanceMax,
-              radiusMin: datum.radiusMin,
-              radiusMax: datum.radiusMax,
-              orientation: datum.orientation,
-              tilt: datum.tilt
-            );
-          } else {
-            yield new PointerCancelEvent(
-              timeStamp: timeStamp,
-              pointer: state.pointer,
-              kind: kind,
-              position: position,
-              obscured: datum.obscured,
-              pressureMin: datum.pressureMin,
-              pressureMax: datum.pressureMax,
-              distance: datum.distance,
-              distanceMax: datum.distanceMax,
-              radiusMin: datum.radiusMin,
-              radiusMax: datum.radiusMax,
-              orientation: datum.orientation,
-              tilt: datum.tilt
-            );
-          }
-          yield new PointerRemovedEvent(
-            timeStamp: timeStamp,
-            pointer: state.pointer,
-            kind: kind,
-            obscured: datum.obscured,
-            pressureMin: datum.pressureMin,
-            pressureMax: datum.pressureMax,
-            distanceMax: datum.distanceMax,
-            radiusMin: datum.radiusMin,
-            radiusMax: datum.radiusMax
-          );
-          _pointers.remove(datum.pointer);
-          break;
-        default:
-          // TODO(ianh): once https://github.com/flutter/flutter/issues/720 is
-          // done, add real support for PointerAddedEvent and PointerRemovedEvent
-          assert(false);
-      }
-    }
-  }
-
-  static const Map<PointerKind, PointerDeviceKind> _pointerKindMap = const <PointerKind, PointerDeviceKind>{
-    PointerKind.TOUCH: PointerDeviceKind.touch,
-    PointerKind.MOUSE: PointerDeviceKind.mouse,
-    PointerKind.STYLUS: PointerDeviceKind.stylus,
-    PointerKind.INVERTED_STYLUS: PointerDeviceKind.invertedStylus,
-  };
-}
-
-class BindingObserver {
-  bool didPopRoute() => false;
-  void didChangeSize(Size size) { }
-  void didChangeLocale(ui.Locale locale) { }
-}
+export 'package:flutter/gestures.dart' show HitTestResult;
 
 /// The glue between the render tree and the Flutter engine.
-class FlutterBinding extends HitTestTarget {
+abstract class Renderer extends Scheduler
+  implements HitTestable {
 
-  FlutterBinding({ RenderBox root: null, RenderView renderViewOverride }) {
-    assert(_instance == null);
+  void initInstances() {
+    super.initInstances();
     _instance = this;
-
-    ui.window.onPointerPacket = _handlePointerPacket;
-    ui.window.onMetricsChanged = _handleMetricsChanged;
-    ui.window.onLocaleChanged = _handleLocaleChanged;
-    ui.window.onPopRoute = _handlePopRoute;
-
-    if (renderViewOverride == null) {
-      _renderView = new RenderView(child: root);
-      _renderView.attach();
-      _handleMetricsChanged();
-      _renderView.scheduleInitialFrame();
-    } else {
-      _renderView = renderViewOverride;
-    }
-    assert(_renderView != null);
-    scheduler.addPersistentFrameCallback(_handlePersistentFrameCallback);
-
-    assert(_instance == this);
+    ui.window.onMetricsChanged = handleMetricsChanged;
+    initRenderView();
+    addPersistentFrameCallback(_handlePersistentFrameCallback);
   }
 
-  /// The singleton instance of the binding.
-  static FlutterBinding get instance => _instance;
-  static FlutterBinding _instance;
+  static Renderer _instance;
+  static Renderer get instance => _instance;
+
+  void initRenderView() {
+    if (renderView == null) {
+      renderView = new RenderView();
+      renderView.scheduleInitialFrame();
+    }
+    handleMetricsChanged(); // configures _renderView's metrics
+  }
 
   /// The render tree that's attached to the output surface.
   RenderView get renderView => _renderView;
   RenderView _renderView;
-
-  final List<BindingObserver> _observers = new List<BindingObserver>();
-
-  void addObserver(BindingObserver observer) => _observers.add(observer);
-  bool removeObserver(BindingObserver observer) => _observers.remove(observer);
-
-  void _handleMetricsChanged() {
-    Size size = ui.window.size;
-    _renderView.rootConstraints = new ViewConstraints(size: size);
-    for (BindingObserver observer in _observers)
-      observer.didChangeSize(size);
+  void set renderView(RenderView value) {
+    if (_renderView == value)
+      return;
+    if (_renderView != null)
+      _renderView.detach();
+    _renderView = value;
+    if (_renderView != null)
+      _renderView.attach();
   }
 
-  void _handleLocaleChanged() {
-    dispatchLocaleChanged(ui.window.locale);
-  }
-
-  void dispatchLocaleChanged(ui.Locale locale) {
-    for (BindingObserver observer in _observers)
-      observer.didChangeLocale(locale);
+  void handleMetricsChanged() {
+    _renderView.rootConstraints = new ViewConstraints(size: ui.window.size);
   }
 
   void _handlePersistentFrameCallback(Duration timeStamp) {
     beginFrame();
   }
 
-  /// Pump the rendering pipeline to generate a frame for the given time stamp.
+  /// Pump the rendering pipeline to generate a frame.
   void beginFrame() {
     RenderObject.flushLayout();
     _renderView.updateCompositingBits();
@@ -268,82 +67,26 @@ class FlutterBinding extends HitTestTarget {
     _renderView.compositeFrame();
   }
 
-  void _handlePopRoute() {
-    for (BindingObserver observer in _observers) {
-      if (observer.didPopRoute())
-        return;
-    }
-  }
-
-  void _handlePointerPacket(ByteData serializedPacket) {
-    final mojo_bindings.Message message = new mojo_bindings.Message(
-      serializedPacket,
-      <mojo_core.MojoHandle>[],
-      serializedPacket.lengthInBytes,
-      0
-    );
-    final PointerPacket packet = PointerPacket.deserialize(message);
-    for (PointerEvent event in _PointerEventConverter.expand(packet.pointers))
-      _handlePointerEvent(event);
-  }
-
-  /// A router that routes all pointer events received from the engine.
-  final PointerRouter pointerRouter = new PointerRouter();
-
-  /// State for all pointers which are currently down.
-  ///
-  /// The state of hovering pointers is not tracked because that would require
-  /// hit-testing on every frame.
-  Map<int, HitTestResult> _hitTests = <int, HitTestResult>{};
-
-  void _handlePointerEvent(PointerEvent event) {
-    if (event is PointerDownEvent) {
-      assert(!_hitTests.containsKey(event.pointer));
-      _hitTests[event.pointer] = hitTest(event.position);
-    } else if (event is! PointerUpEvent) {
-      assert(event.down == _hitTests.containsKey(event.pointer));
-      if (!event.down)
-        return; // we currently ignore add, remove, and hover move events
-    }
-    assert(_hitTests[event.pointer] != null);
-    dispatchEvent(event, _hitTests[event.pointer]);
-    if (event is PointerUpEvent) {
-      assert(_hitTests.containsKey(event.pointer));
-      _hitTests.remove(event.pointer);
-    }
-  }
-
-  /// Determine which [HitTestTarget] objects are located at a given position.
-  HitTestResult hitTest(Point position) {
-    HitTestResult result = new HitTestResult();
+  void hitTest(HitTestResult result, Point position) {
     _renderView.hitTest(result, position: position);
-    result.add(new HitTestEntry(this));
-    return result;
-  }
-
-  /// Dispatch the given event to the path of the given hit test result
-  void dispatchEvent(PointerEvent event, HitTestResult result) {
-    assert(result != null);
-    for (HitTestEntry entry in result.path)
-      entry.target.handleEvent(event, entry);
-  }
-
-  void handleEvent(PointerEvent event, HitTestEntry entry) {
-    pointerRouter.route(event);
-    if (event is PointerDownEvent) {
-      GestureArena.instance.close(event.pointer);
-    } else if (event is PointerUpEvent) {
-      GestureArena.instance.sweep(event.pointer);
-    }
+    super.hitTest(result, position);
   }
 }
 
 /// Prints a textual representation of the entire render tree.
 void debugDumpRenderTree() {
-  debugPrint(FlutterBinding.instance.renderView.toStringDeep());
+  debugPrint(Renderer.instance.renderView.toStringDeep());
 }
 
 /// Prints a textual representation of the entire layer tree.
 void debugDumpLayerTree() {
-  debugPrint(FlutterBinding.instance.renderView.layer.toStringDeep());
+  debugPrint(Renderer.instance.renderView.layer.toStringDeep());
+}
+
+/// A concrete binding for applications that use the Rendering framework
+/// directly. This is the glue that binds the framework to the Flutter engine.
+class RenderingFlutterBinding extends BindingBase with Scheduler, Renderer, Pointerer {
+  RenderingFlutterBinding({ RenderBox root }) {
+    renderView.child = root;
+  }
 }

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

@@ -11,12 +11,11 @@ import 'package:flutter/scheduler.dart';
 import 'package:vector_math/vector_math_64.dart';
 
 import 'debug.dart';
-import 'hit_test.dart';
 import 'layer.dart';
 import 'node.dart';
 
 export 'layer.dart';
-export 'hit_test.dart';
+export 'package:flutter/gestures.dart' show HitTestEntry, HitTestResult;
 
 typedef ui.Shader ShaderCallback(Rect bounds);
 
@@ -551,7 +550,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
       assert(parent == this.parent);
     } else {
       _nodesNeedingLayout.add(this);
-      scheduler.ensureVisualUpdate();
+      Scheduler.instance.ensureVisualUpdate();
     }
   }
 
@@ -916,7 +915,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
       // ourselves without involving any other nodes.
       assert(_layer != null);
       _nodesNeedingPaint.add(this);
-      scheduler.ensureVisualUpdate();
+      Scheduler.instance.ensureVisualUpdate();
     } else if (parent is RenderObject) {
       // We don't have our own layer; one of our ancestors will take
       // care of updating the layer we're in and when they do that
@@ -930,7 +929,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
       // then we have to paint ourselves, since nobody else can paint
       // us. We don't add ourselves to _nodesNeedingPaint in this
       // case, because the root is always told to paint regardless.
-      scheduler.ensureVisualUpdate();
+      Scheduler.instance.ensureVisualUpdate();
     }
   }
 

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

@@ -73,7 +73,7 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
   void scheduleInitialFrame() {
     scheduleInitialLayout();
     scheduleInitialPaint(new TransformLayer(transform: _logicalToDeviceTransform));
-    scheduler.ensureVisualUpdate();
+    Scheduler.instance.ensureVisualUpdate();
   }
 
   // We never call layout() on this class, so this should never get

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

@@ -7,6 +7,7 @@ import 'dart:developer';
 import 'dart:ui' as ui;
 
 import 'package:collection/priority_queue.dart';
+import 'package:flutter/services.dart';
 
 /// Slows down animations by this factor to help in development.
 double timeDilation = 1.0;
@@ -80,12 +81,18 @@ class Priority {
 /// the task should be run.
 ///
 /// Tasks always run in the idle time after a frame has been committed.
-class Scheduler {
+abstract class Scheduler extends BindingBase {
   /// Requires clients to use the [scheduler] singleton
-  Scheduler._() {
+
+  void initInstances() {
+    super.initInstances();
+    _instance = this;
     ui.window.onBeginFrame = handleBeginFrame;
   }
 
+  static Scheduler _instance;
+  static Scheduler get instance => _instance;
+
   SchedulingStrategy schedulingStrategy = new DefaultSchedulingStrategy();
 
   final PriorityQueue _taskQueue = new HeapPriorityQueue<_TaskEntry>(
@@ -120,7 +127,7 @@ class Scheduler {
     if (_taskQueue.isEmpty)
       return;
     _TaskEntry entry = _taskQueue.first;
-    if (schedulingStrategy.shouldRunTaskWithPriority(entry.priority)) {
+    if (schedulingStrategy.shouldRunTaskWithPriority(priority: entry.priority, scheduler: this)) {
       try {
         (_taskQueue.removeFirst().task)();
       } finally {
@@ -295,17 +302,15 @@ class Scheduler {
   }
 }
 
-final Scheduler scheduler = new Scheduler._();
-
 abstract class SchedulingStrategy {
-  bool shouldRunTaskWithPriority(int priority);
+  bool shouldRunTaskWithPriority({ int priority, Scheduler scheduler });
 }
 
 class DefaultSchedulingStrategy implements SchedulingStrategy {
   // TODO(floitsch): for now we only expose the priority. It might be
   // interesting to provide more info (like, how long the task ran the last
   // time).
-  bool shouldRunTaskWithPriority(int priority) {
+  bool shouldRunTaskWithPriority({ int priority, Scheduler scheduler }) {
     if (scheduler.transientCallbackCount > 0)
       return priority >= Priority.animation._value;
     return true;

packages/flutter/lib/src/services/asset_bundle.dart

@@ -100,7 +100,8 @@ class MojoAssetBundle extends AssetBundle {
 AssetBundle _initRootBundle() {
   try {
     AssetBundleProxy bundle = new AssetBundleProxy.fromHandle(
-        new core.MojoHandle(internals.takeRootBundleHandle()));
+      new core.MojoHandle(internals.takeRootBundleHandle())
+    );
     return new MojoAssetBundle(bundle);
   } catch (e) {
     return null;

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

@@ -0,0 +1,32 @@
+// 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.
+
+/// Base class for mixins that provide singleton services (also known as
+/// "bindings").
+///
+/// To use this class in a mixin, inherit from it and implement
+/// [initInstances()]. The mixin is guaranteed to only be constructed once in
+/// the lifetime of the app (more precisely, it will assert if constructed twice
+/// in checked mode).
+abstract class BindingBase {
+  BindingBase() {
+    assert(!_debugInitialized);
+    initInstances();
+    assert(_debugInitialized);
+  }
+
+  static bool _debugInitialized = false;
+
+  /// The initialization method. Subclasses override this method to hook into
+  /// the platform and otherwise configure their services. Subclasses must call
+  /// "super.initInstances()".
+  ///
+  /// By convention, if the service is to be provided as a singleton, it should
+  /// be exposed as `MixinClassName.instance`, a static getter that returns
+  /// `MixinClassName._instance`, a static field that is set by
+  /// `initInstances()`.
+  void initInstances() {
+    assert(() { _debugInitialized = true; return true; });
+  }
+}

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

@@ -2,35 +2,82 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:ui' as ui;
 import 'dart:developer';
 
+import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
+import 'package:flutter/services.dart';
 
 import 'framework.dart';
 
-/// The glue that binds the widget framework to the Flutter engine.
-class WidgetFlutterBinding extends FlutterBinding {
+class BindingObserver {
+  bool didPopRoute() => false;
+  void didChangeSize(Size size) { }
+  void didChangeLocale(ui.Locale locale) { }
+}
 
-  WidgetFlutterBinding() {
-    BuildableElement.scheduleBuildFor = scheduleBuildFor;
+/// A concrete binding for applications based on the Widgets framework.
+/// This is the glue that binds the framework to the Flutter engine.
+class WidgetFlutterBinding extends BindingBase with Scheduler, Pointerer, Renderer {
+
+  WidgetFlutterBinding._();
+
+  /// Creates and initializes the WidgetFlutterBinding. This constructor is
+  /// idempotent; calling it a second time will just return the
+  /// previously-created instance.
+  static WidgetFlutterBinding ensureInitialized() {
+    if (_instance == null)
+      new WidgetFlutterBinding._();
+    return _instance;
   }
 
-  /// Ensures that there is a FlutterBinding object instantiated.
-  static void ensureInitialized() {
-    if (FlutterBinding.instance == null)
-      new WidgetFlutterBinding();
-    assert(FlutterBinding.instance is WidgetFlutterBinding);
+  initInstances() {
+    super.initInstances();
+    _instance = this;
+    BuildableElement.scheduleBuildFor = scheduleBuildFor;
+    ui.window.onLocaleChanged = handleLocaleChanged;
+    ui.window.onPopRoute = handlePopRoute;
   }
 
   /// The one static instance of this class.
   ///
-  /// Only valid after ensureInitialized() (or the WidgetFlutterBinding
-  /// constructor) has been called.  If another FlutterBinding subclass is
-  /// instantiated before this one (e.g. bindings from other frameworks based on
-  /// the Flutter "rendering" library), then WidgetFlutterBinding.instance will
-  /// not be valid (and will throw in checked mode).
-  static WidgetFlutterBinding get instance => FlutterBinding.instance;
+  /// Only valid after the WidgetFlutterBinding constructor) has been called.
+  /// Only one binding class can be instantiated per process. If another
+  /// BindingBase implementation has been instantiated before this one (e.g.
+  /// bindings from other frameworks based on the Flutter "rendering" library),
+  /// then WidgetFlutterBinding.instance will not be valid (and will throw in
+  /// checked mode).
+  static WidgetFlutterBinding _instance;
+  static WidgetFlutterBinding get instance => _instance;
+
+  final List<BindingObserver> _observers = new List<BindingObserver>();
+
+  void addObserver(BindingObserver observer) => _observers.add(observer);
+  bool removeObserver(BindingObserver observer) => _observers.remove(observer);
+
+  void handleMetricsChanged() {
+    super.handleMetricsChanged();
+    for (BindingObserver observer in _observers)
+      observer.didChangeSize(ui.window.size);
+  }
+
+  void handleLocaleChanged() {
+    dispatchLocaleChanged(ui.window.locale);
+  }
+
+  void dispatchLocaleChanged(ui.Locale locale) {
+    for (BindingObserver observer in _observers)
+      observer.didChangeLocale(locale);
+  }
+
+  void handlePopRoute() {
+    for (BindingObserver observer in _observers) {
+      if (observer.didPopRoute())
+        break;
+    }
+  }
 
   void beginFrame() {
     buildDirtyElements();
@@ -46,7 +93,7 @@ class WidgetFlutterBinding extends FlutterBinding {
     assert(!_dirtyElements.contains(element));
     assert(element.dirty);
     if (_dirtyElements.isEmpty)
-      scheduler.ensureVisualUpdate();
+      ensureVisualUpdate();
     _dirtyElements.add(element);
   }
 
@@ -93,8 +140,7 @@ class WidgetFlutterBinding extends FlutterBinding {
 
 /// Inflate the given widget and attach it to the screen.
 void runApp(Widget app) {
-  WidgetFlutterBinding.ensureInitialized();
-  WidgetFlutterBinding.instance._runApp(app);
+  WidgetFlutterBinding.ensureInitialized()._runApp(app);
 }
 
 /// Print a string representation of the currently running app.
@@ -157,7 +203,7 @@ class RenderObjectToWidgetElement<T extends RenderObject> extends RenderObjectEl
 
   Element _child;
 
-  static const _rootChild = const Object();
+  static const _rootChildSlot = const Object();
 
   void visitChildren(ElementVisitor visitor) {
     if (_child != null)
@@ -167,19 +213,19 @@ class RenderObjectToWidgetElement<T extends RenderObject> extends RenderObjectEl
   void mount(Element parent, dynamic newSlot) {
     assert(parent == null);
     super.mount(parent, newSlot);
-    _child = updateChild(_child, widget.child, _rootChild);
+    _child = updateChild(_child, widget.child, _rootChildSlot);
   }
 
   void update(RenderObjectToWidgetAdapter<T> newWidget) {
     super.update(newWidget);
     assert(widget == newWidget);
-    _child = updateChild(_child, widget.child, _rootChild);
+    _child = updateChild(_child, widget.child, _rootChildSlot);
   }
 
   RenderObjectWithChildMixin<T> get renderObject => super.renderObject;
 
   void insertChildRenderObject(RenderObject child, dynamic slot) {
-    assert(slot == _rootChild);
+    assert(slot == _rootChildSlot);
     renderObject.child = child;
   }
 

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

@@ -96,6 +96,7 @@ class Draggable<T> extends DraggableBase<T> {
   GestureRecognizer createRecognizer(PointerRouter router, DragStartCallback starter) {
     return new MultiTapGestureRecognizer(
       router: router,
+      gestureArena: Pointerer.instance.gestureArena,
       onTapDown: starter
     );
   }
@@ -122,6 +123,7 @@ class LongPressDraggable<T> extends DraggableBase<T> {
   GestureRecognizer createRecognizer(PointerRouter router, DragStartCallback starter) {
     return new MultiTapGestureRecognizer(
       router: router,
+      gestureArena: Pointerer.instance.gestureArena,
       longTapDelay: kLongPressTimeout,
       onLongTapDown: (Point position, int pointer) {
         userFeedback.performHapticFeedback(HapticFeedbackType.VIRTUAL_KEY);
@@ -133,7 +135,7 @@ class LongPressDraggable<T> extends DraggableBase<T> {
 
 class _DraggableState<T> extends State<DraggableBase<T>> implements GestureArenaMember {
 
-  PointerRouter get router => FlutterBinding.instance.pointerRouter;
+  PointerRouter get router => Pointerer.instance.pointerRouter;
 
   void initState() {
     super.initState();
@@ -144,7 +146,7 @@ class _DraggableState<T> extends State<DraggableBase<T>> implements GestureArena
   Map<int, GestureArenaEntry> _activePointers = <int, GestureArenaEntry>{};
 
   void _routePointer(PointerEvent event) {
-    _activePointers[event.pointer] = GestureArena.instance.add(event.pointer, this);
+    _activePointers[event.pointer] = Pointerer.instance.gestureArena.add(event.pointer, this);
     _recognizer.addPointer(event);
   }
 
@@ -315,7 +317,8 @@ class _DragAvatar<T> {
   void update(Point globalPosition) {
     _lastOffset = globalPosition - dragStartPoint;
     _entry.markNeedsBuild();
-    HitTestResult result = WidgetFlutterBinding.instance.hitTest(globalPosition + feedbackOffset);
+    HitTestResult result = new HitTestResult();
+    WidgetFlutterBinding.instance.hitTest(result, globalPosition + feedbackOffset);
     _DragTargetState target = _getDragTarget(result.path);
     if (target == _activeTarget)
       return;

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

@@ -121,7 +121,7 @@ class GestureDetector extends StatefulComponent {
 }
 
 class _GestureDetectorState extends State<GestureDetector> {
-  PointerRouter get _router => FlutterBinding.instance.pointerRouter;
+  PointerRouter get _router => Pointerer.instance.pointerRouter;
 
   TapGestureRecognizer _tap;
   DoubleTapGestureRecognizer _doubleTap;
@@ -165,7 +165,7 @@ class _GestureDetectorState extends State<GestureDetector> {
     if (config.onTapDown == null && config.onTapUp == null && config.onTap == null && config.onTapCancel == null) {
       _tap = _ensureDisposed(_tap);
     } else {
-      _tap ??= new TapGestureRecognizer(router: _router);
+      _tap ??= new TapGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _tap
         ..onTapDown = config.onTapDown
         ..onTapUp = config.onTapUp
@@ -178,7 +178,7 @@ class _GestureDetectorState extends State<GestureDetector> {
     if (config.onDoubleTap == null) {
       _doubleTap = _ensureDisposed(_doubleTap);
     } else {
-      _doubleTap ??= new DoubleTapGestureRecognizer(router: _router);
+      _doubleTap ??= new DoubleTapGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _doubleTap.onDoubleTap = config.onDoubleTap;
     }
   }
@@ -187,7 +187,7 @@ class _GestureDetectorState extends State<GestureDetector> {
     if (config.onLongPress == null) {
       _longPress = _ensureDisposed(_longPress);
     } else {
-      _longPress ??= new LongPressGestureRecognizer(router: _router);
+      _longPress ??= new LongPressGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _longPress.onLongPress = config.onLongPress;
     }
   }
@@ -196,7 +196,7 @@ class _GestureDetectorState extends State<GestureDetector> {
     if (config.onVerticalDragStart == null && config.onVerticalDragUpdate == null && config.onVerticalDragEnd == null) {
       _verticalDrag = _ensureDisposed(_verticalDrag);
     } else {
-      _verticalDrag ??= new VerticalDragGestureRecognizer(router: _router);
+      _verticalDrag ??= new VerticalDragGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _verticalDrag
         ..onStart = config.onVerticalDragStart
         ..onUpdate = config.onVerticalDragUpdate
@@ -208,7 +208,7 @@ class _GestureDetectorState extends State<GestureDetector> {
     if (config.onHorizontalDragStart == null && config.onHorizontalDragUpdate == null && config.onHorizontalDragEnd == null) {
       _horizontalDrag = _ensureDisposed(_horizontalDrag);
     } else {
-      _horizontalDrag ??= new HorizontalDragGestureRecognizer(router: _router);
+      _horizontalDrag ??= new HorizontalDragGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _horizontalDrag
         ..onStart = config.onHorizontalDragStart
         ..onUpdate = config.onHorizontalDragUpdate
@@ -221,7 +221,7 @@ class _GestureDetectorState extends State<GestureDetector> {
       _pan = _ensureDisposed(_pan);
     } else {
       assert(_scale == null);  // Scale is a superset of pan; just use scale
-      _pan ??= new PanGestureRecognizer(router: _router);
+      _pan ??= new PanGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _pan
         ..onStart = config.onPanStart
         ..onUpdate = config.onPanUpdate
@@ -234,7 +234,7 @@ class _GestureDetectorState extends State<GestureDetector> {
       _scale = _ensureDisposed(_scale);
     } else {
       assert(_pan == null);  // Scale is a superset of pan; just use scale
-      _scale ??= new ScaleGestureRecognizer(router: _router);
+      _scale ??= new ScaleGestureRecognizer(router: _router, gestureArena: Pointerer.instance.gestureArena);
       _scale
         ..onStart = config.onScaleStart
         ..onUpdate = config.onScaleUpdate

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

@@ -455,7 +455,7 @@ class HeroController extends NavigatorObserver {
   void _checkForHeroQuest() {
     if (_from != null && _to != null && _from != _to) {
       _to.offstage = _to.performance.status != PerformanceStatus.completed;
-      scheduler.addPostFrameCallback(_updateQuest);
+      Scheduler.instance.addPostFrameCallback(_updateQuest);
     }
   }
 

packages/flutter_test/lib/src/widget_tester.dart

@@ -17,13 +17,15 @@ typedef Point SizeToPointFunction(Size size);
 
 class WidgetTester {
   WidgetTester._(FakeAsync async)
-    : async = async,
+    : binding = WidgetFlutterBinding.ensureInitialized(),
+      async = async,
       clock = async.getClock(new DateTime.utc(2015, 1, 1)) {
     timeDilation = 1.0;
     ui.window.onBeginFrame = null;
     runApp(new ErrorWidget()); // flush out the last build entirely
   }
 
+  final WidgetFlutterBinding binding;
   final FakeAsync async;
   final Clock clock;
 
@@ -34,15 +36,16 @@ class WidgetTester {
 
   void setLocale(String languageCode, String countryCode) {
     ui.Locale locale = new ui.Locale(languageCode, countryCode);
-    FlutterBinding.instance.dispatchLocaleChanged(locale);
+    binding.dispatchLocaleChanged(locale);
     async.flushMicrotasks();
   }
 
   void pump([ Duration duration ]) {
     if (duration != null)
       async.elapse(duration);
-    scheduler.handleBeginFrame(new Duration(
-        milliseconds: clock.now().millisecondsSinceEpoch));
+    binding.handleBeginFrame(new Duration(
+      milliseconds: clock.now().millisecondsSinceEpoch)
+    );
     async.flushMicrotasks();
   }
 
@@ -58,7 +61,7 @@ class WidgetTester {
     }
     return result;
   }
-  List<Layer> get layers => _layers(FlutterBinding.instance.renderView.layer);
+  List<Layer> get layers => _layers(binding.renderView.layer);
 
 
   void walkElements(ElementVisitor visitor) {
@@ -66,7 +69,7 @@ class WidgetTester {
       visitor(element);
       element.visitChildren(walk);
     }
-    WidgetFlutterBinding.instance.renderViewElement.visitChildren(walk);
+    binding.renderViewElement.visitChildren(walk);
   }
 
   Element findElement(bool predicate(Element element)) {
@@ -184,10 +187,14 @@ class WidgetTester {
     _dispatchEvent(event, _hitTest(location));
   }
 
-  HitTestResult _hitTest(Point location) => WidgetFlutterBinding.instance.hitTest(location);
+  HitTestResult _hitTest(Point location) {
+    HitTestResult result = new HitTestResult();
+    binding.hitTest(result, location);
+    return result;
+  }
 
   void _dispatchEvent(PointerEvent event, HitTestResult result) {
-    WidgetFlutterBinding.instance.dispatchEvent(event, result);
+    binding.dispatchEvent(event, result);
   }
 
 }

packages/unit/test/engine/canvas_test_disabled.dart

@@ -1,3 +1,7 @@
+// 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 'dart:ui' as ui;
 import 'dart:ui' show Rect, Color, Paint;
 

packages/unit/test/engine/color_test.dart

@@ -1,3 +1,7 @@
+// 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 'dart:ui';
 
 import 'package:test/test.dart';

packages/unit/test/engine/paragraph_builder_test.dart

@@ -1,3 +1,7 @@
+// 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 'dart:ui';
 
 import 'package:test/test.dart';

packages/unit/test/engine/rect_test.dart

@@ -1,3 +1,7 @@
+// 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 'dart:ui';
 
 import 'package:test/test.dart';

packages/unit/test/examples/sector_layout_test.dart

@@ -1,3 +1,7 @@
+// 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:test/test.dart';
 
 import '../rendering/rendering_tester.dart';

packages/unit/test/gestures/arena_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/gestures.dart';
 import 'package:test/test.dart';
 

packages/unit/test/gestures/double_tap_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/gestures.dart';
 import 'package:quiver/testing/async.dart';
 import 'package:test/test.dart';
@@ -77,7 +81,11 @@ void main() {
 
   test('Should recognize double tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -85,25 +93,25 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(doubleTapRecognized, isFalse);
     router.route(down2);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up2);
     expect(doubleTapRecognized, isTrue);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(doubleTapRecognized, isTrue);
 
     tap.dispose();
@@ -111,7 +119,11 @@ void main() {
 
   test('Inter-tap distance cancels double tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -119,25 +131,25 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down3);
-    GestureArena.instance.close(3);
+    gestureArena.close(3);
     expect(doubleTapRecognized, isFalse);
     router.route(down3);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up3);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(3);
+    gestureArena.sweep(3);
     expect(doubleTapRecognized, isFalse);
 
     tap.dispose();
@@ -145,7 +157,11 @@ void main() {
 
   test('Intra-tap distance cancels double tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -153,7 +169,7 @@ void main() {
     };
 
     tap.addPointer(down4);
-    GestureArena.instance.close(4);
+    gestureArena.close(4);
     expect(doubleTapRecognized, isFalse);
     router.route(down4);
     expect(doubleTapRecognized, isFalse);
@@ -162,18 +178,18 @@ void main() {
     expect(doubleTapRecognized, isFalse);
     router.route(up4);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(4);
+    gestureArena.sweep(4);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down2);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     tap.dispose();
@@ -181,7 +197,11 @@ void main() {
 
   test('Inter-tap delay cancels double tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -190,26 +210,26 @@ void main() {
 
     new FakeAsync().run((FakeAsync async) {
       tap.addPointer(down1);
-      GestureArena.instance.close(1);
+      gestureArena.close(1);
       expect(doubleTapRecognized, isFalse);
       router.route(down1);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up1);
       expect(doubleTapRecognized, isFalse);
-      GestureArena.instance.sweep(1);
+      gestureArena.sweep(1);
       expect(doubleTapRecognized, isFalse);
 
       async.elapse(new Duration(milliseconds: 5000));
       tap.addPointer(down2);
-      GestureArena.instance.close(2);
+      gestureArena.close(2);
       expect(doubleTapRecognized, isFalse);
       router.route(down2);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up2);
       expect(doubleTapRecognized, isFalse);
-      GestureArena.instance.sweep(2);
+      gestureArena.sweep(2);
       expect(doubleTapRecognized, isFalse);
     });
 
@@ -218,7 +238,11 @@ void main() {
 
   test('Inter-tap delay resets double tap, allowing third tap to be a double-tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -227,38 +251,38 @@ void main() {
 
     new FakeAsync().run((FakeAsync async) {
       tap.addPointer(down1);
-      GestureArena.instance.close(1);
+      gestureArena.close(1);
       expect(doubleTapRecognized, isFalse);
       router.route(down1);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up1);
       expect(doubleTapRecognized, isFalse);
-      GestureArena.instance.sweep(1);
+      gestureArena.sweep(1);
       expect(doubleTapRecognized, isFalse);
 
       async.elapse(new Duration(milliseconds: 5000));
       tap.addPointer(down2);
-      GestureArena.instance.close(2);
+      gestureArena.close(2);
       expect(doubleTapRecognized, isFalse);
       router.route(down2);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up2);
       expect(doubleTapRecognized, isFalse);
-      GestureArena.instance.sweep(2);
+      gestureArena.sweep(2);
       expect(doubleTapRecognized, isFalse);
 
       async.elapse(new Duration(milliseconds: 100));
       tap.addPointer(down5);
-      GestureArena.instance.close(5);
+      gestureArena.close(5);
       expect(doubleTapRecognized, isFalse);
       router.route(down5);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up5);
       expect(doubleTapRecognized, isTrue);
-      GestureArena.instance.sweep(5);
+      gestureArena.sweep(5);
       expect(doubleTapRecognized, isTrue);
     });
 
@@ -267,7 +291,11 @@ void main() {
 
   test('Intra-tap delay does not cancel double tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -276,7 +304,7 @@ void main() {
 
     new FakeAsync().run((FakeAsync async) {
       tap.addPointer(down1);
-      GestureArena.instance.close(1);
+      gestureArena.close(1);
       expect(doubleTapRecognized, isFalse);
       router.route(down1);
       expect(doubleTapRecognized, isFalse);
@@ -284,18 +312,18 @@ void main() {
       async.elapse(new Duration(milliseconds: 1000));
       router.route(up1);
       expect(doubleTapRecognized, isFalse);
-      GestureArena.instance.sweep(1);
+      gestureArena.sweep(1);
       expect(doubleTapRecognized, isFalse);
 
       tap.addPointer(down2);
-      GestureArena.instance.close(2);
+      gestureArena.close(2);
       expect(doubleTapRecognized, isFalse);
       router.route(down2);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up2);
       expect(doubleTapRecognized, isTrue);
-      GestureArena.instance.sweep(2);
+      gestureArena.sweep(2);
       expect(doubleTapRecognized, isTrue);
     });
 
@@ -304,7 +332,11 @@ void main() {
 
   test('Should not recognize two overlapping taps', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -312,25 +344,25 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up2);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(doubleTapRecognized, isFalse);
 
     tap.dispose();
@@ -338,7 +370,11 @@ void main() {
 
   test('Should recognize one tap of group followed by second tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -346,36 +382,36 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up2);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isTrue);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isTrue);
 
     tap.dispose();
@@ -384,7 +420,11 @@ void main() {
 
   test('Should cancel on arena reject during first tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -393,8 +433,8 @@ void main() {
 
     tap.addPointer(down1);
     TestGestureArenaMember member = new TestGestureArenaMember();
-    GestureArenaEntry entry = GestureArena.instance.add(1, member);
-    GestureArena.instance.close(1);
+    GestureArenaEntry entry = gestureArena.add(1, member);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
@@ -404,18 +444,18 @@ void main() {
     entry.resolve(GestureDisposition.accepted);
     expect(member.accepted, isTrue);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(doubleTapRecognized, isFalse);
     router.route(down2);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up2);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(doubleTapRecognized, isFalse);
 
     tap.dispose();
@@ -423,7 +463,11 @@ void main() {
 
   test('Should cancel on arena reject between taps', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -432,29 +476,29 @@ void main() {
 
     tap.addPointer(down1);
     TestGestureArenaMember member = new TestGestureArenaMember();
-    GestureArenaEntry entry = GestureArena.instance.add(1, member);
-    GestureArena.instance.close(1);
+    GestureArenaEntry entry = gestureArena.add(1, member);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     entry.resolve(GestureDisposition.accepted);
     expect(member.accepted, isTrue);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(doubleTapRecognized, isFalse);
     router.route(down2);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up2);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(doubleTapRecognized, isFalse);
 
     tap.dispose();
@@ -462,7 +506,11 @@ void main() {
 
   test('Should cancel on arena reject during last tap', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -471,19 +519,19 @@ void main() {
 
     tap.addPointer(down1);
     TestGestureArenaMember member = new TestGestureArenaMember();
-    GestureArenaEntry entry = GestureArena.instance.add(1, member);
-    GestureArena.instance.close(1);
+    GestureArenaEntry entry = gestureArena.add(1, member);
+    gestureArena.close(1);
     expect(doubleTapRecognized, isFalse);
     router.route(down1);
     expect(doubleTapRecognized, isFalse);
 
     router.route(up1);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(doubleTapRecognized, isFalse);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(doubleTapRecognized, isFalse);
     router.route(down2);
     expect(doubleTapRecognized, isFalse);
@@ -493,7 +541,7 @@ void main() {
 
     router.route(up2);
     expect(doubleTapRecognized, isFalse);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(doubleTapRecognized, isFalse);
 
     tap.dispose();
@@ -501,7 +549,11 @@ void main() {
 
   test('Passive gesture should trigger on double tap cancel', () {
     PointerRouter router = new PointerRouter();
-    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    DoubleTapGestureRecognizer tap = new DoubleTapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool doubleTapRecognized = false;
     tap.onDoubleTap = () {
@@ -511,15 +563,15 @@ void main() {
     new FakeAsync().run((FakeAsync async) {
       tap.addPointer(down1);
       TestGestureArenaMember member = new TestGestureArenaMember();
-      GestureArena.instance.add(1, member);
-      GestureArena.instance.close(1);
+      gestureArena.add(1, member);
+      gestureArena.close(1);
       expect(doubleTapRecognized, isFalse);
       router.route(down1);
       expect(doubleTapRecognized, isFalse);
 
       router.route(up1);
       expect(doubleTapRecognized, isFalse);
-      GestureArena.instance.sweep(1);
+      gestureArena.sweep(1);
       expect(doubleTapRecognized, isFalse);
 
       expect(member.accepted, isFalse);

packages/unit/test/gestures/long_press_test.dart

@@ -1,3 +1,7 @@
+// 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:quiver/testing/async.dart';
 import 'package:flutter/gestures.dart';
 import 'package:test/test.dart';
@@ -15,7 +19,11 @@ const PointerUpEvent up = const PointerUpEvent(
 void main() {
   test('Should recognize long press', () {
     PointerRouter router = new PointerRouter();
-    LongPressGestureRecognizer longPress = new LongPressGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    LongPressGestureRecognizer longPress = new LongPressGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool longPressRecognized = false;
     longPress.onLongPress = () {
@@ -24,7 +32,7 @@ void main() {
 
     new FakeAsync().run((FakeAsync async) {
       longPress.addPointer(down);
-      GestureArena.instance.close(5);
+      gestureArena.close(5);
       expect(longPressRecognized, isFalse);
       router.route(down);
       expect(longPressRecognized, isFalse);
@@ -39,7 +47,11 @@ void main() {
 
   test('Up cancels long press', () {
     PointerRouter router = new PointerRouter();
-    LongPressGestureRecognizer longPress = new LongPressGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    LongPressGestureRecognizer longPress = new LongPressGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool longPressRecognized = false;
     longPress.onLongPress = () {
@@ -48,7 +60,7 @@ void main() {
 
     new FakeAsync().run((FakeAsync async) {
       longPress.addPointer(down);
-      GestureArena.instance.close(5);
+      gestureArena.close(5);
       expect(longPressRecognized, isFalse);
       router.route(down);
       expect(longPressRecognized, isFalse);
@@ -65,8 +77,15 @@ void main() {
 
   test('Should recognize both tap down and long press', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
-    LongPressGestureRecognizer longPress = new LongPressGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    LongPressGestureRecognizer longPress = new LongPressGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool tapDownRecognized = false;
     tap.onTapDown = (_) {
@@ -81,7 +100,7 @@ void main() {
     new FakeAsync().run((FakeAsync async) {
       tap.addPointer(down);
       longPress.addPointer(down);
-      GestureArena.instance.close(5);
+      gestureArena.close(5);
       expect(tapDownRecognized, isFalse);
       expect(longPressRecognized, isFalse);
       router.route(down);

packages/unit/test/gestures/lsq_solver_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/gestures.dart';
 import 'package:test/test.dart';
 

packages/unit/test/gestures/pointer_router_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart';
 import 'package:test/test.dart';

packages/unit/test/gestures/scale_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart';
 import 'package:test/test.dart';
@@ -5,8 +9,15 @@ import 'package:test/test.dart';
 void main() {
   test('Should recognize scale gestures', () {
     PointerRouter router = new PointerRouter();
-    ScaleGestureRecognizer scale = new ScaleGestureRecognizer(router: router);
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    ScaleGestureRecognizer scale = new ScaleGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool didStartScale = false;
     Point updatedFocalPoint;
@@ -37,7 +48,7 @@ void main() {
     scale.addPointer(down);
     tap.addPointer(down);
 
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(didStartScale, isFalse);
     expect(updatedScale, isNull);
     expect(updatedFocalPoint, isNull);
@@ -67,7 +78,7 @@ void main() {
     PointerDownEvent down2 = pointer2.down(const Point(10.0, 20.0));
     scale.addPointer(down2);
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     router.route(down2);
 
     expect(didEndScale, isTrue);
@@ -100,7 +111,7 @@ void main() {
     PointerDownEvent down3 = pointer3.down(const Point(25.0, 35.0));
     scale.addPointer(down3);
     tap.addPointer(down3);
-    GestureArena.instance.close(3);
+    gestureArena.close(3);
     router.route(down3);
 
     expect(didEndScale, isTrue);

packages/unit/test/gestures/scroll_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart';
 import 'package:test/test.dart';
@@ -5,8 +9,15 @@ import 'package:test/test.dart';
 void main() {
   test('Should recognize pan', () {
     PointerRouter router = new PointerRouter();
-    PanGestureRecognizer pan = new PanGestureRecognizer(router: router);
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    PanGestureRecognizer pan = new PanGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool didStartPan = false;
     pan.onStart = (_) {
@@ -32,7 +43,7 @@ void main() {
     PointerDownEvent down = pointer.down(const Point(10.0, 10.0));
     pan.addPointer(down);
     tap.addPointer(down);
-    GestureArena.instance.close(5);
+    gestureArena.close(5);
     expect(didStartPan, isFalse);
     expect(updatedScrollDelta, isNull);
     expect(didEndPan, isFalse);

packages/unit/test/gestures/tap_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/gestures.dart';
 import 'package:quiver/testing/async.dart';
 import 'package:test/test.dart';
@@ -49,7 +53,11 @@ void main() {
 
   test('Should recognize tap', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool tapRecognized = false;
     tap.onTap = () {
@@ -57,14 +65,14 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(tapRecognized, isFalse);
     router.route(down1);
     expect(tapRecognized, isFalse);
 
     router.route(up1);
     expect(tapRecognized, isTrue);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(tapRecognized, isTrue);
 
     tap.dispose();
@@ -72,7 +80,11 @@ void main() {
 
   test('No duplicate tap events', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     int tapsRecognized = 0;
     tap.onTap = () {
@@ -80,25 +92,25 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(tapsRecognized, 0);
     router.route(down1);
     expect(tapsRecognized, 0);
 
     router.route(up1);
     expect(tapsRecognized, 1);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(tapsRecognized, 1);
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(tapsRecognized, 1);
     router.route(down1);
     expect(tapsRecognized, 1);
 
     router.route(up1);
     expect(tapsRecognized, 2);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(tapsRecognized, 2);
 
     tap.dispose();
@@ -106,7 +118,11 @@ void main() {
 
   test('Should not recognize two overlapping taps', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     int tapsRecognized = 0;
     tap.onTap = () {
@@ -114,13 +130,13 @@ void main() {
     };
 
     tap.addPointer(down1);
-    GestureArena.instance.close(1);
+    gestureArena.close(1);
     expect(tapsRecognized, 0);
     router.route(down1);
     expect(tapsRecognized, 0);
 
     tap.addPointer(down2);
-    GestureArena.instance.close(2);
+    gestureArena.close(2);
     expect(tapsRecognized, 0);
     router.route(down1);
     expect(tapsRecognized, 0);
@@ -128,12 +144,12 @@ void main() {
 
     router.route(up1);
     expect(tapsRecognized, 1);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(tapsRecognized, 1);
 
     router.route(up2);
     expect(tapsRecognized, 1);
-    GestureArena.instance.sweep(2);
+    gestureArena.sweep(2);
     expect(tapsRecognized, 1);
 
     tap.dispose();
@@ -141,7 +157,11 @@ void main() {
 
   test('Distance cancels tap', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool tapRecognized = false;
     tap.onTap = () {
@@ -153,7 +173,7 @@ void main() {
     };
 
     tap.addPointer(down3);
-    GestureArena.instance.close(3);
+    gestureArena.close(3);
     expect(tapRecognized, isFalse);
     expect(tapCanceled, isFalse);
     router.route(down3);
@@ -166,7 +186,7 @@ void main() {
     router.route(up3);
     expect(tapRecognized, isFalse);
     expect(tapCanceled, isTrue);
-    GestureArena.instance.sweep(3);
+    gestureArena.sweep(3);
     expect(tapRecognized, isFalse);
     expect(tapCanceled, isTrue);
 
@@ -175,7 +195,11 @@ void main() {
 
   test('Timeout does not cancel tap', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool tapRecognized = false;
     tap.onTap = () {
@@ -184,7 +208,7 @@ void main() {
 
     new FakeAsync().run((FakeAsync async) {
       tap.addPointer(down1);
-      GestureArena.instance.close(1);
+      gestureArena.close(1);
       expect(tapRecognized, isFalse);
       router.route(down1);
       expect(tapRecognized, isFalse);
@@ -193,7 +217,7 @@ void main() {
       expect(tapRecognized, isFalse);
       router.route(up1);
       expect(tapRecognized, isTrue);
-      GestureArena.instance.sweep(1);
+      gestureArena.sweep(1);
       expect(tapRecognized, isTrue);
     });
 
@@ -202,7 +226,11 @@ void main() {
 
   test('Should yield to other arena members', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool tapRecognized = false;
     tap.onTap = () {
@@ -211,16 +239,16 @@ void main() {
 
     tap.addPointer(down1);
     TestGestureArenaMember member = new TestGestureArenaMember();
-    GestureArenaEntry entry = GestureArena.instance.add(1, member);
-    GestureArena.instance.hold(1);
-    GestureArena.instance.close(1);
+    GestureArenaEntry entry = gestureArena.add(1, member);
+    gestureArena.hold(1);
+    gestureArena.close(1);
     expect(tapRecognized, isFalse);
     router.route(down1);
     expect(tapRecognized, isFalse);
 
     router.route(up1);
     expect(tapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(tapRecognized, isFalse);
 
     entry.resolve(GestureDisposition.accepted);
@@ -231,7 +259,11 @@ void main() {
 
   test('Should trigger on release of held arena', () {
     PointerRouter router = new PointerRouter();
-    TapGestureRecognizer tap = new TapGestureRecognizer(router: router);
+    GestureArena gestureArena = new GestureArena();
+    TapGestureRecognizer tap = new TapGestureRecognizer(
+      router: router,
+      gestureArena: gestureArena
+    );
 
     bool tapRecognized = false;
     tap.onTap = () {
@@ -240,16 +272,16 @@ void main() {
 
     tap.addPointer(down1);
     TestGestureArenaMember member = new TestGestureArenaMember();
-    GestureArenaEntry entry = GestureArena.instance.add(1, member);
-    GestureArena.instance.hold(1);
-    GestureArena.instance.close(1);
+    GestureArenaEntry entry = gestureArena.add(1, member);
+    gestureArena.hold(1);
+    gestureArena.close(1);
     expect(tapRecognized, isFalse);
     router.route(down1);
     expect(tapRecognized, isFalse);
 
     router.route(up1);
     expect(tapRecognized, isFalse);
-    GestureArena.instance.sweep(1);
+    gestureArena.sweep(1);
     expect(tapRecognized, isFalse);
 
     entry.resolve(GestureDisposition.rejected);

packages/unit/test/gestures/velocity_tracker_data.dart

@@ -1,3 +1,7 @@
+// 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:flutter/gestures.dart';
 
 const List<PointerEvent> velocityEventData = const <PointerEvent>[

packages/unit/test/gestures/velocity_tracker_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/gestures.dart';
 import 'package:test/test.dart';
 import 'velocity_tracker_data.dart';

packages/unit/test/harness/trivial_test.dart

@@ -1,3 +1,7 @@
+// 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:test/test.dart';
 
 void main() {

packages/unit/test/painting/edge_dims_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/painting.dart';
 
 import 'package:test/test.dart';

packages/unit/test/rendering/box_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:test/test.dart';

packages/unit/test/rendering/flex_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 

packages/unit/test/rendering/grid_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 

packages/unit/test/rendering/image_test.dart

@@ -1,3 +1,7 @@
+// 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 'dart:ui' as ui;
 
 import 'package:flutter/rendering.dart';

packages/unit/test/rendering/intrinsic_width_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 

packages/unit/test/rendering/offstage_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:test/test.dart';

packages/unit/test/rendering/overflow_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:test/test.dart';

packages/unit/test/rendering/positioned_box_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 

packages/unit/test/rendering/rendering_tester.dart

@@ -1,11 +1,19 @@
+// 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:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:flutter/services.dart';
 
 const Size _kTestViewSize = const Size(800.0, 600.0);
 
 class TestRenderView extends RenderView {
   TestRenderView() {
-    attach();
     rootConstraints = new ViewConstraints(size: _kTestViewSize);
+  }
+  void scheduleInitialFrame() {
     scheduleInitialLayout();
     scheduleInitialPaint(new TransformLayer(transform: new Matrix4.identity()));
   }
@@ -17,18 +25,37 @@ enum EnginePhase {
   composite
 }
 
-RenderView _renderView;
-RenderView get renderView => _renderView;
+class TestRenderingFlutterBinding extends BindingBase with Scheduler, Renderer, Pointerer {
+  void initRenderView() {
+    if (renderView == null) {
+      renderView = new TestRenderView();
+      renderView.scheduleInitialFrame();
+    }
+  }
+
+  EnginePhase phase = EnginePhase.composite;
+
+  void beginFrame() {
+    RenderObject.flushLayout();
+    if (phase == EnginePhase.layout)
+      return;
+    renderer.renderView.updateCompositingBits();
+    RenderObject.flushPaint();
+    if (phase == EnginePhase.paint)
+      return;
+    renderer.renderView.compositeFrame();
+  }
+}
+
+TestRenderingFlutterBinding _renderer;
+TestRenderingFlutterBinding get renderer => _renderer;
 
 void layout(RenderBox box, { BoxConstraints constraints, EnginePhase phase: EnginePhase.layout }) {
   assert(box != null); // if you want to just repump the last box, call pumpFrame().
 
-  if (renderView == null)
-    _renderView = new TestRenderView();
-
-  if (renderView.child != null)
-    renderView.child = null;
+  _renderer ??= new TestRenderingFlutterBinding();
 
+  renderer.renderView.child = null; 
   if (constraints != null) {
     box = new RenderPositionedBox(
       child: new RenderConstrainedBox(
@@ -37,21 +64,15 @@ void layout(RenderBox box, { BoxConstraints constraints, EnginePhase phase: Engi
       )
     );
   }
-
-  renderView.child = box;
+  renderer.renderView.child = box;
 
   pumpFrame(phase: phase);
 }
 
 void pumpFrame({ EnginePhase phase: EnginePhase.layout }) {
-  RenderObject.flushLayout();
-  if (phase == EnginePhase.layout)
-    return;
-  renderView.updateCompositingBits();
-  RenderObject.flushPaint();
-  if (phase == EnginePhase.paint)
-    return;
-  renderView.compositeFrame();
+  assert(renderer != null);
+  renderer.phase = phase;
+  renderer.beginFrame();
 }
 
 class TestCallbackPainter extends CustomPainter {

packages/unit/test/rendering/size_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 

packages/unit/test/rendering/stack_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 

packages/unit/test/rendering/viewport_test.dart

@@ -1,3 +1,7 @@
+// 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:flutter/rendering.dart';
 import 'package:test/test.dart';
 
@@ -26,11 +30,11 @@ void main() {
     HitTestResult result;
 
     result = new HitTestResult();
-    renderView.hitTest(result, position: new Point(15.0, 0.0));
+    renderer.renderView.hitTest(result, position: new Point(15.0, 0.0));
     expect(result.path.first.target.runtimeType, equals(TestRenderView));
 
     result = new HitTestResult();
-    renderView.hitTest(result, position: new Point(15.0, 15.0));
+    renderer.renderView.hitTest(result, position: new Point(15.0, 15.0));
     expect(result.path.first.target, equals(green));
   });
 }

packages/unit/test/scheduler/animation_test.dart

@@ -1,7 +1,16 @@
+// 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:flutter/scheduler.dart';
+import 'package:flutter/services.dart';
 import 'package:test/test.dart';
 
+class TestSchedulerBinding extends BindingBase with Scheduler { }
+
 void main() {
+  Scheduler scheduler = new TestSchedulerBinding();
+
   test("Check for a time dilation being in effect", () {
     expect(timeDilation, equals(1.0));
   });

packages/unit/test/scheduler/scheduler_test.dart.disabled

@@ -2,43 +2,52 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// This test is disabled because it triggers https://github.com/dart-lang/sdk/issues/25246
+
 import 'package:flutter/scheduler.dart';
+import 'package:flutter/services.dart';
 import 'package:test/test.dart';
 
+class TestSchedulerBinding extends BindingBase with Scheduler { }
+
 class TestStrategy implements SchedulingStrategy {
   int allowedPriority = 10000;
 
-  bool shouldRunTaskWithPriority(int priority) {
+  bool shouldRunTaskWithPriority({ int priority, Scheduler scheduler }) {
     return priority >= allowedPriority;
   }
 }
 
 void main() {
   test("Tasks are executed in the right order", () {
-    var strategy = new TestStrategy();
+    Scheduler scheduler = new TestSchedulerBinding();
+    TestStrategy strategy = new TestStrategy();
     scheduler.schedulingStrategy = strategy;
-    List input = [2, 23, 23, 11, 0, 80, 3];
-    List executedTasks = [];
+    List<int> input = <int>[2, 23, 23, 11, 0, 80, 3];
+    List<int> executedTasks = <int>[];
 
     void scheduleAddingTask(int x) {
       scheduler.scheduleTask(() { executedTasks.add(x); }, Priority.idle + x);
     }
 
-    for (int x in input) {
+    for (int x in input)
       scheduleAddingTask(x);
-    }
+
     strategy.allowedPriority = 100;
-    for (int i = 0; i < 3; i++) scheduler.handleEventLoopCallback();
+    for (int i = 0; i < 3; i += 1)
+      scheduler.handleEventLoopCallback();
     expect(executedTasks.isEmpty, isTrue);
 
     strategy.allowedPriority = 50;
-    for (int i = 0; i < 3; i++) scheduler.handleEventLoopCallback();
+    for (int i = 0; i < 3; i += 1)
+      scheduler.handleEventLoopCallback();
     expect(executedTasks.length, equals(1));
     expect(executedTasks.single, equals(80));
     executedTasks.clear();
 
     strategy.allowedPriority = 20;
-    for (int i = 0; i < 3; i++) scheduler.handleEventLoopCallback();
+    for (int i = 0; i < 3; i += 1)
+      scheduler.handleEventLoopCallback();
     expect(executedTasks.length, equals(2));
     expect(executedTasks[0], equals(23));
     expect(executedTasks[1], equals(23));
@@ -48,21 +57,24 @@ void main() {
     scheduleAddingTask(19);
     scheduleAddingTask(5);
     scheduleAddingTask(97);
-    for (int i = 0; i < 3; i++) scheduler.handleEventLoopCallback();
+    for (int i = 0; i < 3; i += 1)
+      scheduler.handleEventLoopCallback();
     expect(executedTasks.length, equals(2));
     expect(executedTasks[0], equals(99));
     expect(executedTasks[1], equals(97));
     executedTasks.clear();
 
     strategy.allowedPriority = 10;
-    for (int i = 0; i < 3; i++) scheduler.handleEventLoopCallback();
+    for (int i = 0; i < 3; i += 1)
+      scheduler.handleEventLoopCallback();
     expect(executedTasks.length, equals(2));
     expect(executedTasks[0], equals(19));
     expect(executedTasks[1], equals(11));
     executedTasks.clear();
 
     strategy.allowedPriority = 1;
-    for (int i = 0; i < 4; i++) scheduler.handleEventLoopCallback();
+    for (int i = 0; i < 4; i += 1)
+      scheduler.handleEventLoopCallback();
     expect(executedTasks.length, equals(3));
     expect(executedTasks[0], equals(5));
     expect(executedTasks[1], equals(3));

packages/unit/test/widget/animated_container_test.dart

@@ -4,7 +4,6 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/scheduler.dart';
 import 'package:flutter/widgets.dart';
 import 'package:test/test.dart';
 
@@ -65,9 +64,9 @@ void main() {
           )
         )
       );
-      expect(scheduler.transientCallbackCount, 0);
+      expect(tester.binding.transientCallbackCount, 0);
       tester.pump(new Duration(seconds: 1));
-      expect(scheduler.transientCallbackCount, 0);
+      expect(tester.binding.transientCallbackCount, 0);
       tester.pumpWidget(
         new AnimatedContainer(
           duration: const Duration(milliseconds: 200),
@@ -76,9 +75,9 @@ void main() {
           )
         )
       );
-      expect(scheduler.transientCallbackCount, 0);
+      expect(tester.binding.transientCallbackCount, 0);
       tester.pump(new Duration(seconds: 1));
-      expect(scheduler.transientCallbackCount, 0);
+      expect(tester.binding.transientCallbackCount, 0);
       tester.pumpWidget(
         new AnimatedContainer(
           duration: const Duration(milliseconds: 200),
@@ -87,9 +86,9 @@ void main() {
           )
         )
       );
-      expect(scheduler.transientCallbackCount, 1); // this is the only time an animation should have started!
+      expect(tester.binding.transientCallbackCount, 1); // this is the only time an animation should have started!
       tester.pump(new Duration(seconds: 1));
-      expect(scheduler.transientCallbackCount, 0);
+      expect(tester.binding.transientCallbackCount, 0);
       tester.pumpWidget(
         new AnimatedContainer(
           duration: const Duration(milliseconds: 200),
@@ -98,7 +97,7 @@ void main() {
           )
         )
       );
-      expect(scheduler.transientCallbackCount, 0);
+      expect(tester.binding.transientCallbackCount, 0);
     });
   });
 }