When a list is scrolling, children can't be tapped (#5222) (#5348)

examples/flutter_gallery/test/smoke_test.dart

@@ -9,6 +9,8 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_gallery/gallery/item.dart' show GalleryItem, kAllGalleryItems;
 import 'package:flutter_gallery/main.dart' as flutter_gallery_main;
 
+const String kCaption = 'Flutter Gallery';
+
 final List<String> demoCategories = new LinkedHashSet<String>.from(
   kAllGalleryItems.map((GalleryItem item) => item.category)
 ).toList();
@@ -43,8 +45,9 @@ Future<Null> smokeDemo(WidgetTester tester, String routeName) async {
 
   await tester.tap(menuItem);
   await tester.pump(); // Launch the demo.
-  await tester
-      .pump(const Duration(seconds: 1)); // Wait until the demo has opened.
+  await tester.pump(const Duration(seconds: 1)); // Wait until the demo has opened.
+
+  expect(find.text(kCaption), findsNothing);
 
   // Go back
   if (routeName == '/pesto') {
@@ -64,16 +67,14 @@ Future<Null> smokeDemo(WidgetTester tester, String routeName) async {
 }
 
 void main() {
-  TestWidgetsFlutterBinding binding =
-      TestWidgetsFlutterBinding.ensureInitialized();
-  if (binding is LiveTestWidgetsFlutterBinding) binding.allowAllFrames = true;
-
   testWidgets('Flutter Gallery app smoke test', (WidgetTester tester) async {
     flutter_gallery_main
         .main(); // builds the app and schedules a frame but doesn't trigger one
     await tester.pump(); // see https://github.com/flutter/flutter/issues/1865
     await tester.pump(); // triggers a frame
 
+    expect(find.text(kCaption), findsOneWidget);
+
     final List<double> scrollDeltas = new List<double>();
     double previousY = tester.getTopRight(find.text(demoCategories[0])).y;
     for (String routeName in routeNames) {
@@ -87,15 +88,17 @@ void main() {
       final String routeName = routeNames[i];
       await smokeDemo(tester, routeName);
       await tester.scroll(findGalleryItemByRouteName(tester, routeName), new Offset(0.0, scrollDeltas[i]));
-      await tester.pump();
+      await tester.pump(); // start the scroll
+      await tester.pump(const Duration(milliseconds: 500)); // wait for overscroll to timeout, if necessary
+      await tester.pump(const Duration(milliseconds: 2000)); // wait for overscroll to fade away, if necessary
+      tester.binding.debugAssertNoTransientCallbacks('A transient callback was still active after leaving route $routeName');
     }
 
     Finder navigationMenuButton = findNavigationMenuButton(tester);
     expect(navigationMenuButton, findsOneWidget);
     await tester.tap(navigationMenuButton);
     await tester.pump(); // Start opening drawer.
-    await tester
-        .pump(const Duration(seconds: 1)); // Wait until it's really opened.
+    await tester.pump(const Duration(seconds: 1)); // Wait until it's really opened.
 
     // switch theme
     await tester.tap(find.text('Dark'));

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

@@ -259,7 +259,8 @@ class ScrollableState<T extends Scrollable> extends State<T> {
 
   @override
   void dispose() {
-    _stop();
+    _controller.dispose();
+    _simulation = null;
     super.dispose();
   }
 
@@ -367,8 +368,10 @@ class ScrollableState<T extends Scrollable> extends State<T> {
   }
 
   void _handleAnimationStatusChanged(AnimationStatus status) {
-    if (!_controller.isAnimating)
-      _simulation = null;
+    setState(() {
+      if (!_controller.isAnimating)
+        _simulation = null;
+    });
   }
 
   void _setScrollOffset(double newScrollOffset, { DragUpdateDetails details }) {
@@ -579,9 +582,12 @@ class ScrollableState<T extends Scrollable> extends State<T> {
   }
 
   void _stop() {
+    assert(mounted);
     assert(_controller.isAnimating || _simulation == null);
-    _controller.stop();
-    _simulation = null;
+    setState(() {
+      _controller.stop();
+      _simulation = null;
+    });
   }
 
   void _handleDragStart(DragStartDetails details) {
@@ -652,7 +658,10 @@ class ScrollableState<T extends Scrollable> extends State<T> {
       key: _gestureDetectorKey,
       gestures: buildGestureDetectors(),
       behavior: HitTestBehavior.opaque,
-      child: buildContent(context)
+      child: new IgnorePointer(
+        ignoring: _controller.isAnimating,
+        child: buildContent(context)
+      )
     );
   }
 

packages/flutter/test/widget/scrollable_fling_test.dart

@@ -58,4 +58,49 @@ void main() {
 
     expect(result1, lessThan(result2)); // iOS (result2) is slipperier than Android (result1)
   });
+
+  testWidgets('fling and tap to stop', (WidgetTester tester) async {
+    List<String> log = <String>[];
+
+    List<Widget> textWidgets = <Widget>[];
+    for (int i = 0; i < 250; i++)
+      textWidgets.add(new GestureDetector(onTap: () { log.add('tap $i'); }, child: new Text('$i')));
+    await tester.pumpWidget(new Block(children: textWidgets));
+
+    expect(log, equals(<String>[]));
+    await tester.tap(find.byType(Scrollable));
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18']));
+    await tester.fling(find.byType(Scrollable), new Offset(0.0, -200.0), 1000.0);
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18']));
+    await tester.tap(find.byType(Scrollable));
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18']));
+    await tester.tap(find.byType(Scrollable));
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18', 'tap 31']));
+  });
+
+  testWidgets('fling and wait and tap', (WidgetTester tester) async {
+    List<String> log = <String>[];
+
+    List<Widget> textWidgets = <Widget>[];
+    for (int i = 0; i < 250; i++)
+      textWidgets.add(new GestureDetector(onTap: () { log.add('tap $i'); }, child: new Text('$i')));
+    await tester.pumpWidget(new Block(children: textWidgets));
+
+    expect(log, equals(<String>[]));
+    await tester.tap(find.byType(Scrollable));
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18']));
+    await tester.fling(find.byType(Scrollable), new Offset(0.0, -200.0), 1000.0);
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18']));
+    await tester.pump(const Duration(seconds: 50));
+    expect(log, equals(<String>['tap 18']));
+    await tester.tap(find.byType(Scrollable));
+    await tester.pump(const Duration(milliseconds: 50));
+    expect(log, equals(<String>['tap 18', 'tap 48']));
+  });
 }