Add ScrollController (#7910)

If you pass a ScrollController to a Scrollable2, you can use the controller to
read and write the scroll offset without having to find the Scrollable2State
object.

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

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:flutter/animation.dart';
+import 'package:meta/meta.dart';
+
+import 'scroll_position.dart';
+
+class ScrollController {
+  final List<ScrollPosition> _positions = <ScrollPosition>[];
+
+  double get offset {
+    assert(_positions.isNotEmpty, 'ScrollController not attached to any scroll views.');
+    assert(_positions.length == 1, 'ScrollController attached to multiple scroll views.');
+    return _positions.single.pixels;
+  }
+
+  /// Animates the position from its current value to the given value.
+  ///
+  /// Any active animation is canceled. If the user is currently scrolling, that
+  /// action is canceled.
+  ///
+  /// The returned [Future] will complete when the animation ends, whether it
+  /// completed successfully or whether it was interrupted prematurely.
+  ///
+  /// An animation will be interrupted whenever the user attempts to scroll
+  /// manually, or whenever another activity is started, or whenever the
+  /// animation reaches the edge of the viewport and attempts to overscroll. (If
+  /// the [ScrollPosition] does not overscroll but instead allows scrolling
+  /// beyond the extents, then going beyond the extents will not interrupt the
+  /// animation.)
+  ///
+  /// The animation is indifferent to changes to the viewport or content
+  /// dimensions.
+  ///
+  /// Once the animation has completed, the scroll position will attempt to
+  /// begin a ballistic activity in case its value is not stable (for example,
+  /// if it is scrolled beyond the extents and in that situation the scroll
+  /// position would normally bounce back).
+  ///
+  /// The duration must not be zero. To jump to a particular value without an
+  /// animation, use [jumpTo].
+  Future<Null> animateTo(double offset, {
+    @required Duration duration,
+    @required Curve curve,
+  }) {
+    assert(_positions.isNotEmpty, 'ScrollController not attached to any scroll views.');
+    assert(_positions.length == 1, 'ScrollController attached to multiple scroll views.');
+    return _positions.single.animateTo(offset, duration: duration, curve: curve);
+  }
+
+  /// Jumps the scroll position from its current value to the given value,
+  /// without animation, and without checking if the new value is in range.
+  ///
+  /// Any active animation is canceled. If the user is currently scrolling, that
+  /// action is canceled.
+  ///
+  /// If this method changes the scroll position, a sequence of start/update/end
+  /// scroll notifications will be dispatched. No overscroll notifications can
+  /// be generated by this method.
+  ///
+  /// Immediately after the jump, a ballistic activity is started, in case the
+  /// value was out of range.
+  void jumpTo(double value) {
+    assert(_positions.isNotEmpty, 'ScrollController not attached to any scroll views.');
+    assert(_positions.length == 1, 'ScrollController attached to multiple scroll views.');
+     _positions.single.jumpTo(value);
+  }
+
+  /// Register the given position with this controller.
+  ///
+  /// After this function returns, the [animateTo] and [jumpTo] methods on this
+  /// controller will manipulate the given position.
+  void attach(ScrollPosition position) {
+    assert(!_positions.contains(position));
+    _positions.add(position);
+  }
+
+  /// Unregister the given position with this controller.
+  ///
+  /// After this function returns, the [animateTo] and [jumpTo] methods on this
+  /// controller will not manipulate the given position.
+  void detach(ScrollPosition position) {
+    assert(_positions.contains(position));
+    _positions.remove(position);
+  }
+}

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

@@ -151,20 +151,20 @@ class ScrollPosition extends ViewportOffset {
     final RenderAbstractViewport viewport = RenderAbstractViewport.of(object);
     assert(viewport != null);
 
-    final double to = viewport.getOffsetToReveal(object, alignment).clamp(minScrollExtent, maxScrollExtent);
+    final double target = viewport.getOffsetToReveal(object, alignment).clamp(minScrollExtent, maxScrollExtent);
 
-    if (to == pixels)
+    if (target == pixels)
       return new Future<Null>.value();
 
     if (duration == Duration.ZERO) {
-      jumpTo(to);
+      jumpTo(target);
       return new Future<Null>.value();
     }
 
-    return animate(to: to, duration: duration, curve: curve);
+    return animateTo(target, duration: duration, curve: curve);
   }
 
-  /// Animates the position from its current value to the given value `to`.
+  /// Animates the position from its current value to the given value.
   ///
   /// Any active animation is canceled. If the user is currently scrolling, that
   /// action is canceled.
@@ -188,11 +188,10 @@ class ScrollPosition extends ViewportOffset {
   /// position would normally bounce back).
   ///
   /// The duration must not be zero. To jump to a particular value without an
-  /// animation, use [setPixels].
+  /// animation, use [jumpTo].
   ///
   /// The animation is handled by an [DrivenScrollActivity].
-  Future<Null> animate({
-    @required double to,
+  Future<Null> animateTo(double to, {
     @required Duration duration,
     @required Curve curve,
   }) {
@@ -514,19 +513,19 @@ abstract class ScrollActivity {
   /// [ScrollPosition.beginBallisticActivity].
   void resetActivity() { }
 
-  Notification createScrollStartNotification(Scrollable2State scrollable) {
+  Notification createScrollStartNotification(AbstractScrollState scrollable) {
     return new ScrollStartNotification(scrollable: scrollable);
   }
 
-  Notification createScrollUpdateNotification(Scrollable2State scrollable, double scrollDelta) {
+  Notification createScrollUpdateNotification(AbstractScrollState scrollable, double scrollDelta) {
     return new ScrollUpdateNotification(scrollable: scrollable, scrollDelta: scrollDelta);
   }
 
-  Notification createOverscrollNotification(Scrollable2State scrollable, double overscroll) {
+  Notification createOverscrollNotification(AbstractScrollState scrollable, double overscroll) {
     return new OverscrollNotification(scrollable: scrollable, overscroll: overscroll);
   }
 
-  Notification createScrollEndNotification(Scrollable2State scrollable) {
+  Notification createScrollEndNotification(AbstractScrollState scrollable) {
     return new ScrollEndNotification(scrollable: scrollable);
   }
 
@@ -609,25 +608,25 @@ class DragScrollActivity extends ScrollActivity {
   dynamic _lastDetails;
 
   @override
-  Notification createScrollStartNotification(Scrollable2State scrollable) {
+  Notification createScrollStartNotification(AbstractScrollState scrollable) {
     assert(_lastDetails is DragStartDetails);
     return new ScrollStartNotification(scrollable: scrollable, dragDetails: _lastDetails);
   }
 
   @override
-  Notification createScrollUpdateNotification(Scrollable2State scrollable, double scrollDelta) {
+  Notification createScrollUpdateNotification(AbstractScrollState scrollable, double scrollDelta) {
     assert(_lastDetails is DragUpdateDetails);
     return new ScrollUpdateNotification(scrollable: scrollable, scrollDelta: scrollDelta, dragDetails: _lastDetails);
   }
 
   @override
-  Notification createOverscrollNotification(Scrollable2State scrollable, double overscroll) {
+  Notification createOverscrollNotification(AbstractScrollState scrollable, double overscroll) {
     assert(_lastDetails is DragUpdateDetails);
     return new OverscrollNotification(scrollable: scrollable, overscroll: overscroll, dragDetails: _lastDetails);
   }
 
   @override
-  Notification createScrollEndNotification(Scrollable2State scrollable) {
+  Notification createScrollEndNotification(AbstractScrollState scrollable) {
     assert(_lastDetails is DragEndDetails);
     return new ScrollEndNotification(scrollable: scrollable, dragDetails: _lastDetails);
   }
@@ -689,7 +688,7 @@ class BallisticScrollActivity extends ScrollActivity {
   }
 
   @override
-  Notification createOverscrollNotification(Scrollable2State scrollable, double overscroll) {
+  Notification createOverscrollNotification(AbstractScrollState scrollable, double overscroll) {
     return new OverscrollNotification(scrollable: scrollable, overscroll: overscroll, velocity: velocity);
   }
 
@@ -761,7 +760,7 @@ class DrivenScrollActivity extends ScrollActivity {
   }
 
   @override
-  Notification createOverscrollNotification(Scrollable2State scrollable, double overscroll) {
+  Notification createOverscrollNotification(AbstractScrollState scrollable, double overscroll) {
     return new OverscrollNotification(scrollable: scrollable, overscroll: overscroll, velocity: velocity);
   }
 

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

@@ -7,6 +7,7 @@ import 'package:meta/meta.dart';
 
 import 'framework.dart';
 import 'basic.dart';
+import 'scroll_controller.dart';
 import 'scroll_physics.dart';
 import 'scroll_position.dart';
 import 'scrollable.dart';
@@ -18,6 +19,7 @@ abstract class ScrollView extends StatelessWidget {
     Key key,
     this.scrollDirection: Axis.vertical,
     this.reverse: false,
+    this.controller,
     this.physics,
     this.shrinkWrap: false,
   }) : super(key: key) {
@@ -29,6 +31,8 @@ abstract class ScrollView extends StatelessWidget {
 
   final bool reverse;
 
+  final ScrollController controller;
+
   final ScrollPhysics physics;
 
   final bool shrinkWrap;
@@ -54,6 +58,7 @@ abstract class ScrollView extends StatelessWidget {
     AxisDirection axisDirection = getDirection(context);
     return new Scrollable2(
       axisDirection: axisDirection,
+      controller: controller,
       physics: physics,
       viewportBuilder: (BuildContext context, ViewportOffset offset) {
         if (shrinkWrap) {
@@ -87,6 +92,7 @@ class CustomScrollView extends ScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     this.slivers: const <Widget>[],
@@ -94,6 +100,7 @@ class CustomScrollView extends ScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
   );
@@ -109,6 +116,7 @@ abstract class BoxScrollView extends ScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     this.padding,
@@ -116,6 +124,7 @@ abstract class BoxScrollView extends ScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
   );
@@ -154,6 +163,7 @@ class ListView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -163,6 +173,7 @@ class ListView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -172,6 +183,7 @@ class ListView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -182,6 +194,7 @@ class ListView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -191,6 +204,7 @@ class ListView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -200,6 +214,7 @@ class ListView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -243,6 +258,7 @@ class GridView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -252,6 +268,7 @@ class GridView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -263,6 +280,7 @@ class GridView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -272,6 +290,7 @@ class GridView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -284,6 +303,7 @@ class GridView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -302,6 +322,7 @@ class GridView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -311,6 +332,7 @@ class GridView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.vertical,
     bool reverse: false,
+    ScrollController controller,
     ScrollPhysics physics,
     bool shrinkWrap: false,
     EdgeInsets padding,
@@ -329,6 +351,7 @@ class GridView extends BoxScrollView {
     key: key,
     scrollDirection: scrollDirection,
     reverse: reverse,
+    controller: controller,
     physics: physics,
     shrinkWrap: shrinkWrap,
     padding: padding,
@@ -360,6 +383,7 @@ class PageView extends BoxScrollView {
     Key key,
     Axis scrollDirection: Axis.horizontal,
     bool reverse: false,
+    // TODO(abarth): Add PageController that knows about pages.
     ScrollPhysics physics: const PageScrollPhysics(),
     bool shrinkWrap: false,
     EdgeInsets padding,

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

@@ -22,6 +22,7 @@ import 'notification_listener.dart';
 import 'page_storage.dart';
 import 'scroll_behavior.dart';
 import 'scroll_configuration.dart';
+import 'scroll_controller.dart';
 import 'scroll_notification.dart';
 import 'scroll_position.dart';
 import 'ticker_provider.dart';
@@ -35,6 +36,7 @@ class Scrollable2 extends StatefulWidget {
   Scrollable2({
     Key key,
     this.axisDirection: AxisDirection.down,
+    this.controller,
     this.physics,
     @required this.viewportBuilder,
   }) : super (key: key) {
@@ -44,6 +46,8 @@ class Scrollable2 extends StatefulWidget {
 
   final AxisDirection axisDirection;
 
+  final ScrollController controller;
+
   final ScrollPhysics physics;
 
   final ViewportBuilder viewportBuilder;
@@ -125,14 +129,16 @@ class Scrollable2State extends State<Scrollable2> with TickerProviderStateMixin
     if (config.physics != null)
       physics = config.physics.applyTo(physics);
     final ScrollPosition oldPosition = position;
-    _position = physics.createScrollPosition(physics, this, oldPosition);
-    assert(position != null);
     if (oldPosition != null) {
-      // It's important that we not do this until after the viewport has had a
-      // chance to unregister its listeners from the old position. So, schedule
-      // a microtask to do it.
+      config.controller?.detach(oldPosition);
+      // It's important that we not dispose the old position until after the
+      // viewport has had a chance to unregister its listeners from the old
+      // position. So, schedule a microtask to do it.
       scheduleMicrotask(oldPosition.dispose);
     }
+    _position = physics.createScrollPosition(physics, this, oldPosition);
+    assert(position != null);
+    config.controller?.attach(position);
   }
 
   @override
@@ -153,12 +159,19 @@ class Scrollable2State extends State<Scrollable2> with TickerProviderStateMixin
   @override
   void didUpdateConfig(Scrollable2 oldConfig) {
     super.didUpdateConfig(oldConfig);
+
+    if (config.controller != oldConfig.controller) {
+      oldConfig.controller?.detach(position);
+      config.controller?.attach(position);
+    }
+
     if (_shouldUpdatePosition(oldConfig))
       _updatePosition();
   }
 
   @override
   void dispose() {
+    config.controller?.detach(position);
     position.dispose();
     super.dispose();
   }

packages/flutter/lib/widgets.dart

@@ -47,6 +47,7 @@ export 'src/widgets/raw_keyboard_listener.dart';
 export 'src/widgets/routes.dart';
 export 'src/widgets/scroll_behavior.dart';
 export 'src/widgets/scroll_configuration.dart';
+export 'src/widgets/scroll_controller.dart';
 export 'src/widgets/scroll_notification.dart';
 export 'src/widgets/scroll_physics.dart';
 export 'src/widgets/scroll_position.dart';

packages/flutter/test/widgets/scroll_controller_test.dart

+// Copyright 2017 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/widgets.dart';
+
+import 'states.dart';
+
+void main() {
+  testWidgets('ScrollController control test', (WidgetTester tester) async {
+    ScrollController controller = new ScrollController();
+
+    await tester.pumpWidget(new ListView(
+      controller: controller,
+      children: kStates.map<Widget>((String state) {
+        return new Container(
+          height: 200.0,
+          child: new Text(state),
+        );
+      }).toList()
+    ));
+
+    double realOffset() {
+      return tester.state<Scrollable2State>(find.byType(Scrollable2)).position.pixels;
+    }
+
+    expect(controller.offset, equals(0.0));
+    expect(realOffset(), equals(controller.offset));
+
+    controller.jumpTo(653.0);
+
+    expect(controller.offset, equals(653.0));
+    expect(realOffset(), equals(controller.offset));
+
+    await tester.pump();
+
+    expect(controller.offset, equals(653.0));
+    expect(realOffset(), equals(controller.offset));
+
+    controller.animateTo(326.0, duration: const Duration(milliseconds: 300), curve: Curves.ease);
+    await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 100));
+
+    expect(controller.offset, equals(326.0));
+    expect(realOffset(), equals(controller.offset));
+
+    await tester.pumpWidget(new ListView(
+      key: new Key('second'),
+      controller: controller,
+      children: kStates.map<Widget>((String state) {
+        return new Container(
+          height: 200.0,
+          child: new Text(state),
+        );
+      }).toList()
+    ));
+
+    expect(controller.offset, equals(0.0));
+    expect(realOffset(), equals(controller.offset));
+
+    controller.jumpTo(653.0);
+
+    expect(controller.offset, equals(653.0));
+    expect(realOffset(), equals(controller.offset));
+
+    ScrollController controller2 = new ScrollController();
+
+    await tester.pumpWidget(new ListView(
+      key: new Key('second'),
+      controller: controller2,
+      children: kStates.map<Widget>((String state) {
+        return new Container(
+          height: 200.0,
+          child: new Text(state),
+        );
+      }).toList()
+    ));
+
+    expect(() => controller.offset, throws);
+    expect(controller2.offset, equals(653.0));
+    expect(realOffset(), equals(controller2.offset));
+
+    expect(() => controller.jumpTo(120.0), throws);
+    expect(() => controller.animateTo(132.0, duration: const Duration(milliseconds: 300), curve: Curves.ease), throws);
+
+    await tester.pumpWidget(new ListView(
+      key: new Key('second'),
+      controller: controller2,
+      physics: const BouncingScrollPhysics(),
+      children: kStates.map<Widget>((String state) {
+        return new Container(
+          height: 200.0,
+          child: new Text(state),
+        );
+      }).toList()
+    ));
+
+    expect(controller2.offset, equals(653.0));
+    expect(realOffset(), equals(controller2.offset));
+
+    controller2.jumpTo(432.0);
+
+    expect(controller2.offset, equals(432.0));
+    expect(realOffset(), equals(controller2.offset));
+
+    await tester.pump();
+
+    expect(controller2.offset, equals(432.0));
+    expect(realOffset(), equals(controller2.offset));
+  });
+}

packages/flutter/test/widgets/slivers_appbar_floating_test.dart

@@ -44,7 +44,7 @@ void main() {
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);
@@ -71,7 +71,7 @@ void main() {
     verifyPaintPosition(key2, new Offset(0.0, 600.0), false);
     verifyPaintPosition(key3, new Offset(0.0, 600.0), false);
 
-    position.animate(to: bigHeight - 600.0 + delegate.maxExtent, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight - 600.0 + delegate.maxExtent, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key2, new Offset(0.0, 600.0 - delegate.maxExtent), true);
@@ -79,42 +79,42 @@ void main() {
     verifyPaintPosition(key3, new Offset(0.0, 600.0), false);
 
     assert(delegate.maxExtent * 2.0 < 600.0); // make sure this fits on the test screen...
-    position.animate(to: bigHeight - 600.0 + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight - 600.0 + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key2, new Offset(0.0, 600.0 - delegate.maxExtent * 2.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 0, new Rect.fromLTWH(0.0, 600.0 - delegate.maxExtent * 2.0, 800.0, delegate.maxExtent));
     verifyPaintPosition(key3, new Offset(0.0, 600.0 - delegate.maxExtent), true);
 
-    position.animate(to: bigHeight, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 0, new Rect.fromLTWH(0.0, 0.0, 800.0, delegate.maxExtent));
     verifyPaintPosition(key3, new Offset(0.0, delegate.maxExtent), true);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 0.1, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 0.1, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 0, new Rect.fromLTWH(0.0, 0.0, 800.0, delegate.maxExtent * 0.9));
     verifyPaintPosition(key3, new Offset(0.0, delegate.maxExtent * 0.9), true);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 0.5, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 0.5, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 0, new Rect.fromLTWH(0.0, 0.0, 800.0, delegate.maxExtent * 0.5));
     verifyPaintPosition(key3, new Offset(0.0, delegate.maxExtent * 0.5), true);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 0.9, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 0.9, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyActualBoxPosition(tester, find.byType(Container), 0, new Rect.fromLTWH(0.0, -delegate.maxExtent * 0.4, 800.0, delegate.maxExtent * 0.5));
     verifyPaintPosition(key3, new Offset(0.0, delegate.maxExtent * 0.1), true);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), false);
@@ -141,13 +141,13 @@ void main() {
     verifyPaintPosition(key2, new Offset(0.0, 600.0), false);
     verifyPaintPosition(key3, new Offset(0.0, 600.0), false);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key3, new Offset(0.0, 0.0), true);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 1.9, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 1.9, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), false);
@@ -174,13 +174,13 @@ void main() {
     verifyPaintPosition(key2, new Offset(0.0, 600.0), false);
     verifyPaintPosition(key3, new Offset(0.0, 600.0), false);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 2.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key3, new Offset(0.0, 0.0), true);
 
-    position.animate(to: bigHeight + delegate.maxExtent * 1.9, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(bigHeight + delegate.maxExtent * 1.9, curve: Curves.linear, duration: const Duration(minutes: 1));
     position.updateUserScrollDirection(ScrollDirection.forward); // ignore: INVALID_USE_OF_PROTECTED_MEMBER, since this is using a protected method for testing purposes
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);

packages/flutter/test/widgets/slivers_appbar_pinned_test.dart

@@ -47,7 +47,7 @@ void main() {
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);
@@ -80,21 +80,21 @@ void main() {
     verifyPaintPosition(key3, new Offset(0.0, 600.0), false);
     verifyPaintPosition(key4, new Offset(0.0, 600.0), false);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 550.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(550.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 100));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key3, new Offset(0.0, 200.0), true);
     verifyPaintPosition(key4, new Offset(0.0, 400.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 600.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(600.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 200));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key3, new Offset(0.0, 150.0), true);
     verifyPaintPosition(key4, new Offset(0.0, 350.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 650.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(650.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 300));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
@@ -102,7 +102,7 @@ void main() {
     verifyActualBoxPosition(tester, find.byType(Container), 1, new Rect.fromLTWH(0.0, 100.0, 800.0, 200.0));
     verifyPaintPosition(key4, new Offset(0.0, 300.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 700.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(700.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 400));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
@@ -110,7 +110,7 @@ void main() {
     verifyActualBoxPosition(tester, find.byType(Container), 1, new Rect.fromLTWH(0.0, 100.0, 800.0, 150.0));
     verifyPaintPosition(key4, new Offset(0.0, 250.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 750.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(750.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 500));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
@@ -118,28 +118,28 @@ void main() {
     verifyActualBoxPosition(tester, find.byType(Container), 1, new Rect.fromLTWH(0.0, 100.0, 800.0, 100.0));
     verifyPaintPosition(key4, new Offset(0.0, 200.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 800.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(800.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 60));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key3, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key4, new Offset(0.0, 150.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 850.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(850.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 70));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key3, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key4, new Offset(0.0, 100.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 900.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(900.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 80));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key3, new Offset(0.0, 0.0), true);
     verifyPaintPosition(key4, new Offset(0.0, 50.0), true);
     verifyPaintPosition(key5, new Offset(0.0, 600.0), false);
-    position.animate(to: 950.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(950.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 90));
     verifyPaintPosition(key1, new Offset(0.0, 0.0), false);
     verifyPaintPosition(key2, new Offset(0.0, 0.0), true);
@@ -171,7 +171,7 @@ void main() {
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);

packages/flutter/test/widgets/slivers_appbar_scrolling_test.dart

@@ -38,7 +38,7 @@ void main() {
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);
@@ -65,7 +65,7 @@ void main() {
       ),
     );
     ScrollPosition position = tester.state<Scrollable2State>(find.byType(Scrollable2)).position;
-    position.animate(to: RenderBigSliver.height + delegate.maxExtent - 5.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(RenderBigSliver.height + delegate.maxExtent - 5.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 1000));
     RenderBox box = tester.renderObject<RenderBox>(find.byType(Container));
     Rect rect = new Rect.fromPoints(box.localToGlobal(Point.origin), box.localToGlobal(box.size.bottomRight(Point.origin)));

packages/flutter/test/widgets/slivers_evil_test.dart

@@ -153,31 +153,31 @@ void main() {
     );
     ScrollPosition position = tester.state<Scrollable2State>(find.byType(Scrollable2)).position;
 
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 50));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 122));
 
-    position.animate(to: -10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(-10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 50));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 122));
 
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 50));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 122));
 
-    position.animate(to: -10000.0, curve: Curves.linear, duration: const Duration(seconds: 1));
+    position.animateTo(-10000.0, curve: Curves.linear, duration: const Duration(seconds: 1));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 50));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 122));
 
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(seconds: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(seconds: 1));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 10));
     await tester.pump(const Duration(milliseconds: 50));

packages/flutter/test/widgets/slivers_protocol_test.dart

@@ -40,7 +40,7 @@ void main() {
     expect(position.pixels, 0.0);
     expect(position.minScrollExtent, 0.0);
     expect(position.maxScrollExtent, max);
-    position.animate(to: 10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
+    position.animateTo(10000.0, curve: Curves.linear, duration: const Duration(minutes: 1));
     await tester.pumpUntilNoTransientCallbacks(const Duration(milliseconds: 10));
     expect(position.pixels, max);
     expect(position.minScrollExtent, 0.0);