packages/flutter/test/widgets/overscroll_indicator_test.dart - mirrors/flutter - Git at Google

 // Copyright 2014 The Flutter 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:math' as math;

 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';

 import '../rendering/mock_canvas.dart';

 final Matcher doesNotOverscroll = isNot(paints..circle());

 Future<void> slowDrag(WidgetTester tester, Offset start, Offset offset) async {
   final TestGesture gesture = await tester.startGesture(start);
   for (int index = 0; index < 10; index += 1) {
     await gesture.moveBy(offset);
     await tester.pump(const Duration(milliseconds: 20));
   }
   await gesture.up();
 }

 void main() {
   testWidgets('Overscroll indicator color', (WidgetTester tester) async {
     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
           ],
         ),
       ),
     );
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));

     expect(painter, doesNotOverscroll);

     // the scroll gesture from tester.scroll happens in zero time, so nothing should appear:
     await tester.drag(find.byType(Scrollable), const Offset(0.0, 100.0));
     expect(painter, doesNotOverscroll);
     await tester.pump(); // allow the ticker to register itself
     expect(painter, doesNotOverscroll);
     await tester.pump(const Duration(milliseconds: 100)); // animate
     expect(painter, doesNotOverscroll);

     final TestGesture gesture = await tester.startGesture(const Offset(200.0, 200.0));
     await tester.pump(const Duration(milliseconds: 100)); // animate
     expect(painter, doesNotOverscroll);
     await gesture.up();
     expect(painter, doesNotOverscroll);

     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
     expect(painter, paints..circle(color: const Color(0x0DFFFFFF)));

     await tester.pumpAndSettle(const Duration(seconds: 1));
     expect(painter, doesNotOverscroll);
   });

   testWidgets('Nested scrollable', (WidgetTester tester) async {
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: GlowingOverscrollIndicator(
           axisDirection: AxisDirection.down,
           color: const Color(0x0DFFFFFF),
           notificationPredicate: (ScrollNotification notification) => notification.depth == 1,
           child: const SingleChildScrollView(
             scrollDirection: Axis.horizontal,
             child: SizedBox(
                 width: 600.0,
                 child: CustomScrollView(
                   slivers: <Widget>[
                     SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
                   ],
                 ),
               ),
             ),
           ),
         ),
       );

     final RenderObject outerPainter = tester.renderObject(find.byType(CustomPaint).first);
     final RenderObject innerPainter = tester.renderObject(find.byType(CustomPaint).last);

     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
     expect(outerPainter, paints..circle());
     expect(innerPainter, paints..circle());
   });

   testWidgets('Overscroll indicator changes side when you drag on the other side', (WidgetTester tester) async {
     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
           ],
         ),
       ),
     );
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));

     await slowDrag(tester, const Offset(400.0, 200.0), const Offset(0.0, 10.0));
     expect(painter, paints..circle(x: 400.0));
     await slowDrag(tester, const Offset(100.0, 200.0), const Offset(0.0, 10.0));
     expect(painter, paints..something((Symbol method, List<dynamic> arguments) {
       if (method != #drawCircle)
         return false;
       final Offset center = arguments[0] as Offset;
       if (center.dx < 400.0)
         return true;
       throw 'Dragging on left hand side did not overscroll on left hand side.';
     }));
     await slowDrag(tester, const Offset(700.0, 200.0), const Offset(0.0, 10.0));
     expect(painter, paints..something((Symbol method, List<dynamic> arguments) {
       if (method != #drawCircle)
         return false;
       final Offset center = arguments[0] as Offset;
       if (center.dx > 400.0)
         return true;
       throw 'Dragging on right hand side did not overscroll on right hand side.';
     }));

     await tester.pumpAndSettle(const Duration(seconds: 1));
     expect(painter, doesNotOverscroll);
   });

   testWidgets('Overscroll indicator changes side when you shift sides', (WidgetTester tester) async {
     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
           ],
         ),
       ),
     );
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
     final TestGesture gesture = await tester.startGesture(const Offset(300.0, 200.0));
     await gesture.moveBy(const Offset(0.0, 10.0));
     await tester.pump(const Duration(milliseconds: 20));
     double oldX = 0.0;
     for (int index = 0; index < 10; index += 1) {
       await gesture.moveBy(const Offset(50.0, 50.0));
       await tester.pump(const Duration(milliseconds: 20));
       expect(painter, paints..something((Symbol method, List<dynamic> arguments) {
         if (method != #drawCircle)
           return false;
         final Offset center = arguments[0] as Offset;
         if (center.dx <= oldX)
           throw 'Sliding to the right did not make the center of the radius slide to the right.';
         oldX = center.dx;
         return true;
       }));
     }
     await gesture.up();

     await tester.pumpAndSettle(const Duration(seconds: 1));
     expect(painter, doesNotOverscroll);
   });

   group("Flipping direction of scrollable doesn't change overscroll behavior", () {
     testWidgets('down', (WidgetTester tester) async {
       await tester.pumpWidget(
         const Directionality(
           textDirection: TextDirection.ltr,
           child: CustomScrollView(
             physics: AlwaysScrollableScrollPhysics(),
             slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
         ),
       );
       final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
       await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
       expect(painter, paints..save()..circle()..restore()..save()..scale(y: -1.0)..restore()..restore());

       await tester.pumpAndSettle(const Duration(seconds: 1));
       expect(painter, doesNotOverscroll);
     });

     testWidgets('up', (WidgetTester tester) async {
       await tester.pumpWidget(
         const Directionality(
           textDirection: TextDirection.ltr,
           child: CustomScrollView(
             reverse: true,
             physics: AlwaysScrollableScrollPhysics(),
             slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
         ),
       );
       final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
       await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
       expect(painter, paints..save()..scale(y: -1.0)..restore()..save()..circle()..restore()..restore());

       await tester.pumpAndSettle(const Duration(seconds: 1));
       expect(painter, doesNotOverscroll);
     });
   });

   testWidgets('Overscroll in both directions', (WidgetTester tester) async {
     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           physics: AlwaysScrollableScrollPhysics(),
           slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 20.0)),
           ],
         ),
       ),
     );
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
     expect(painter, paints..circle());
     expect(painter, isNot(paints..circle()..circle()));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, -5.0));
     expect(painter, paints..circle()..circle());

     await tester.pumpAndSettle(const Duration(seconds: 1));
     expect(painter, doesNotOverscroll);
   });

   testWidgets('Overscroll horizontally', (WidgetTester tester) async {
     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: CustomScrollView(
           scrollDirection: Axis.horizontal,
           physics: AlwaysScrollableScrollPhysics(),
           slivers: <Widget>[
             SliverToBoxAdapter(child: SizedBox(height: 20.0)),
           ],
         ),
       ),
     );
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(5.0, 0.0));
     expect(painter, paints..rotate(angle: math.pi / 2.0)..circle()..saveRestore());
     expect(painter, isNot(paints..circle()..circle()));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(-5.0, 0.0));
     expect(
       painter,
       paints
         ..rotate(angle: math.pi / 2.0)
         ..circle()
         ..rotate(angle: math.pi / 2.0)
         ..circle(),
     );

     await tester.pumpAndSettle(const Duration(seconds: 1));
     expect(painter, doesNotOverscroll);
   });

   testWidgets('Nested overscrolls do not throw exceptions', (WidgetTester tester) async {
     await tester.pumpWidget(Directionality(
       textDirection: TextDirection.ltr,
       child: PageView(
         children: <Widget>[
           ListView(
             children: <Widget>[
               Container(
                 width: 2000.0,
                 height: 2000.0,
                 color: const Color(0xFF00FF00),
               ),
             ],
           ),
         ],
       ),
     ));

     await tester.dragFrom(const Offset(100.0, 100.0), const Offset(0.0, 2000.0));
     await tester.pumpAndSettle();
   });

   testWidgets('Changing settings', (WidgetTester tester) async {
     RenderObject painter;

     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: ScrollConfiguration(
           behavior: TestScrollBehavior1(),
           child: CustomScrollView(
             scrollDirection: Axis.horizontal,
             physics: AlwaysScrollableScrollPhysics(),
             reverse: true,
             slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
         ),
       ),
     );
     painter = tester.renderObject(find.byType(CustomPaint));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(5.0, 0.0));
     expect(painter, paints..rotate(angle: math.pi / 2.0)..circle(color: const Color(0x0A00FF00)));
     expect(painter, isNot(paints..circle()..circle()));

     await tester.pumpAndSettle(const Duration(seconds: 1));
     await tester.pumpWidget(
       const Directionality(
         textDirection: TextDirection.ltr,
         child: ScrollConfiguration(
           behavior: TestScrollBehavior2(),
           child: CustomScrollView(
             scrollDirection: Axis.horizontal,
             physics: AlwaysScrollableScrollPhysics(),
             slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 20.0)),
             ],
           ),
         ),
       ),
     );
     painter = tester.renderObject(find.byType(CustomPaint));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(5.0, 0.0));
     expect(painter, paints..rotate(angle: math.pi / 2.0)..circle(color: const Color(0x0A0000FF))..saveRestore());
     expect(painter, isNot(paints..circle()..circle()));
   });

   testWidgets('CustomScrollView overscroll indicator works if there is sliver before center', (WidgetTester tester) async {
     final Key centerKey = UniqueKey();
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ScrollConfiguration(
           behavior: const TestScrollBehavior2(),
           child: CustomScrollView(
             center: centerKey,
             physics: const AlwaysScrollableScrollPhysics(),
             slivers: <Widget>[
               SliverList(
                 delegate: SliverChildBuilderDelegate(
                   (BuildContext context, int index) => Text('First sliver $index'),
                   childCount: 2,
                 ),
               ),
               SliverList(
                 key: centerKey,
                 delegate: SliverChildBuilderDelegate(
                   (BuildContext context, int index) => Text('Second sliver $index'),
                   childCount: 5,
                 ),
               ),
             ],
           ),
         ),
       ),
     );

     expect(find.text('First sliver 1'), findsNothing);

     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 300.0));
     expect(find.text('First sliver 1'), findsOneWidget);
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
     // The scroll offset and paint extend should cancel out each other.
     expect(painter, paints..save()..translate(y: 0.0)..scale()..circle());
   });

   testWidgets('CustomScrollView overscroll indicator works well with [CustomScrollView.center] and [OverscrollIndicatorNotification.paintOffset]', (WidgetTester tester) async {
     final Key centerKey = UniqueKey();
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: ScrollConfiguration(
           behavior: const TestScrollBehavior2(),
           child: NotificationListener<OverscrollIndicatorNotification>(
             onNotification: (OverscrollIndicatorNotification notification) {
               if (notification.leading) {
                 notification.paintOffset = 50.0;
               }
               return false;
             },
             child: CustomScrollView(
               center: centerKey,
               physics: const AlwaysScrollableScrollPhysics(),
               slivers: <Widget>[
                 SliverList(
                   delegate: SliverChildBuilderDelegate(
                     (BuildContext context, int index) => Text('First sliver $index'),
                     childCount: 2,
                   ),
                 ),
                 SliverList(
                   key: centerKey,
                   delegate: SliverChildBuilderDelegate(
                     (BuildContext context, int index) => Text('Second sliver $index'),
                     childCount: 5,
                   ),
                 ),
               ],
             ),
           ),
         ),
       ),
     );

     expect(find.text('First sliver 1'), findsNothing);

     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0)); // offset will be magnified ten times
     expect(find.text('First sliver 1'), findsOneWidget);
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
     // The OverscrollIndicator should respect the [OverscrollIndicatorNotification.paintOffset] setting.
     expect(painter, paints..save()..translate(y: 50.0)..scale()..circle());
   });

   testWidgets('The OverscrollIndicator should not overflow the scrollable view edge', (WidgetTester tester) async {
     // Regressing test for https://github.com/flutter/flutter/issues/64149
     await tester.pumpWidget(
       Directionality(
         textDirection: TextDirection.ltr,
         child: NotificationListener<OverscrollIndicatorNotification>(
           onNotification: (OverscrollIndicatorNotification notification) {
             notification.paintOffset = 50.0; // both the leading and trailing indicator have a 50.0 pixels offset.
             return false;
           },
           child: const CustomScrollView(
             slivers: <Widget>[
               SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
             ],
           ),
         ),
       ),
     );
     final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
     expect(painter, paints..save()..translate(y: 50.0)..scale()..circle());
     // Reverse scroll (30 pixels), and the offset < notification.paintOffset.
     await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -30.0));
     await tester.pump();
     // The OverscrollIndicator should move with the CustomScrollView.
     expect(painter, paints..save()..translate(y: 50.0 - 30.0)..scale()..circle());

     // Reverse scroll (30+20 pixels) and offset == notification.paintOffset.
     await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -20.0));
     await tester.pump();
     expect(painter, paints..save()..translate(y: 50.0 - 50.0)..scale()..circle());

     // Reverse scroll (30+20+10 pixels) and offset > notification.paintOffset.
     await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -10.0));
     await tester.pump();
     // The OverscrollIndicator should not overflow the CustomScrollView's edge.
     expect(painter, paints..save()..translate(y: 50.0 - 50.0)..scale()..circle());

     await tester.pumpAndSettle(); // Finish the leading indicator.

     // trigger the trailing indicator
     await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, -200.0));
     expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0)..scale()..circle());

     // Reverse scroll (30 pixels), and the offset < notification.paintOffset.
     await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 30.0));
     await tester.pump();
     // The OverscrollIndicator should move with the CustomScrollView.
     expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 30.0)..scale()..circle());

     // Reverse scroll (30+20 pixels) and offset == notification.paintOffset.
     await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 20.0));
     await tester.pump();
     expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 50.0)..scale()..circle());

     // Reverse scroll (30+20+10 pixels) and offset > notification.paintOffset.
     await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 10.0));
     await tester.pump();
     // The OverscrollIndicator should not overflow the CustomScrollView's edge.
     expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 50.0)..scale()..circle());
   });

   group('[OverscrollIndicatorNotification.paintOffset] test', () {
     testWidgets('Leading', (WidgetTester tester) async {
       await tester.pumpWidget(
         Directionality(
           textDirection: TextDirection.ltr,
           child: NotificationListener<OverscrollIndicatorNotification>(
             onNotification: (OverscrollIndicatorNotification notification) {
               if (notification.leading) {
                 notification.paintOffset = 50.0;
               }
               return false;
             },
             child: const CustomScrollView(
               slivers: <Widget>[
                 SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
               ],
             ),
           ),
         ),
       );
       final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
       await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
       // The OverscrollIndicator should respect the [OverscrollIndicatorNotification.paintOffset] setting.
       expect(painter, paints..save()..translate(y: 50.0)..scale()..circle());
       // Reverse scroll direction.
       await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -30.0));
       await tester.pump();
       // The OverscrollIndicator should move with the CustomScrollView.
       expect(painter, paints..save()..translate(y: 50.0 - 30.0)..scale()..circle());
     });

     testWidgets('Trailing', (WidgetTester tester) async {
       await tester.pumpWidget(
         Directionality(
           textDirection: TextDirection.ltr,
           child: NotificationListener<OverscrollIndicatorNotification>(
             onNotification: (OverscrollIndicatorNotification notification) {
               if (!notification.leading) {
                 notification.paintOffset = 50.0;
               }
               return false;
             },
             child: const CustomScrollView(
               slivers: <Widget>[
                 SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
               ],
             ),
           ),
         ),
       );
       final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
       await tester.dragFrom(const Offset(200.0, 200.0), const Offset(200.0, -10000.0));
       await tester.pump();
       await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, -5.0));
       // The OverscrollIndicator should respect the [OverscrollIndicatorNotification.paintOffset] setting.
       expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0)..scale()..circle());
       // Reverse scroll direction.
       await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 30.0));
       await tester.pump();
       // The OverscrollIndicator should move with the CustomScrollView.
       expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 30.0)..scale()..circle());
     });
   });
 }

 class TestScrollBehavior1 extends ScrollBehavior {
   const TestScrollBehavior1();

   @override
   Widget buildOverscrollIndicator(BuildContext context, Widget child, ScrollableDetails details) {
     return GlowingOverscrollIndicator(
       axisDirection: details.direction,
       color: const Color(0xFF00FF00),
       child: child,
     );
   }
 }

 class TestScrollBehavior2 extends ScrollBehavior {
   const TestScrollBehavior2();

   @override
   Widget buildOverscrollIndicator(BuildContext context, Widget child, ScrollableDetails details) {
     return GlowingOverscrollIndicator(
       axisDirection: details.direction,
       color: const Color(0xFF0000FF),
       child: child,
     );
   }
 }
	// Copyright 2014 The Flutter 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:math' as math;

	import 'package:flutter/widgets.dart';
	import 'package:flutter_test/flutter_test.dart';

	import '../rendering/mock_canvas.dart';

	final Matcher doesNotOverscroll = isNot(paints..circle());

	Future<void> slowDrag(WidgetTester tester, Offset start, Offset offset) async {
	final TestGesture gesture = await tester.startGesture(start);
	for (int index = 0; index < 10; index += 1) {
	await gesture.moveBy(offset);
	await tester.pump(const Duration(milliseconds: 20));
	}
	await gesture.up();
	}

	void main() {
	testWidgets('Overscroll indicator color', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));

	expect(painter, doesNotOverscroll);

	// the scroll gesture from tester.scroll happens in zero time, so nothing should appear:
	await tester.drag(find.byType(Scrollable), const Offset(0.0, 100.0));
	expect(painter, doesNotOverscroll);
	await tester.pump(); // allow the ticker to register itself
	expect(painter, doesNotOverscroll);
	await tester.pump(const Duration(milliseconds: 100)); // animate
	expect(painter, doesNotOverscroll);

	final TestGesture gesture = await tester.startGesture(const Offset(200.0, 200.0));
	await tester.pump(const Duration(milliseconds: 100)); // animate
	expect(painter, doesNotOverscroll);
	await gesture.up();
	expect(painter, doesNotOverscroll);

	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	expect(painter, paints..circle(color: const Color(0x0DFFFFFF)));

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});

	testWidgets('Nested scrollable', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: GlowingOverscrollIndicator(
	axisDirection: AxisDirection.down,
	color: const Color(0x0DFFFFFF),
	notificationPredicate: (ScrollNotification notification) => notification.depth == 1,
	child: const SingleChildScrollView(
	scrollDirection: Axis.horizontal,
	child: SizedBox(
	width: 600.0,
	child: CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	),
	),
	),
	);

	final RenderObject outerPainter = tester.renderObject(find.byType(CustomPaint).first);
	final RenderObject innerPainter = tester.renderObject(find.byType(CustomPaint).last);

	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	expect(outerPainter, paints..circle());
	expect(innerPainter, paints..circle());
	});

	testWidgets('Overscroll indicator changes side when you drag on the other side', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));

	await slowDrag(tester, const Offset(400.0, 200.0), const Offset(0.0, 10.0));
	expect(painter, paints..circle(x: 400.0));
	await slowDrag(tester, const Offset(100.0, 200.0), const Offset(0.0, 10.0));
	expect(painter, paints..something((Symbol method, List<dynamic> arguments) {
	if (method != #drawCircle)
	return false;
	final Offset center = arguments[0] as Offset;
	if (center.dx < 400.0)
	return true;
	throw 'Dragging on left hand side did not overscroll on left hand side.';
	}));
	await slowDrag(tester, const Offset(700.0, 200.0), const Offset(0.0, 10.0));
	expect(painter, paints..something((Symbol method, List<dynamic> arguments) {
	if (method != #drawCircle)
	return false;
	final Offset center = arguments[0] as Offset;
	if (center.dx > 400.0)
	return true;
	throw 'Dragging on right hand side did not overscroll on right hand side.';
	}));

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});

	testWidgets('Overscroll indicator changes side when you shift sides', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	final TestGesture gesture = await tester.startGesture(const Offset(300.0, 200.0));
	await gesture.moveBy(const Offset(0.0, 10.0));
	await tester.pump(const Duration(milliseconds: 20));
	double oldX = 0.0;
	for (int index = 0; index < 10; index += 1) {
	await gesture.moveBy(const Offset(50.0, 50.0));
	await tester.pump(const Duration(milliseconds: 20));
	expect(painter, paints..something((Symbol method, List<dynamic> arguments) {
	if (method != #drawCircle)
	return false;
	final Offset center = arguments[0] as Offset;
	if (center.dx <= oldX)
	throw 'Sliding to the right did not make the center of the radius slide to the right.';
	oldX = center.dx;
	return true;
	}));
	}
	await gesture.up();

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});

	group("Flipping direction of scrollable doesn't change overscroll behavior", () {
	testWidgets('down', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	physics: AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 20.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	expect(painter, paints..save()..circle()..restore()..save()..scale(y: -1.0)..restore()..restore());

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});

	testWidgets('up', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	reverse: true,
	physics: AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 20.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	expect(painter, paints..save()..scale(y: -1.0)..restore()..save()..circle()..restore()..restore());

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});
	});

	testWidgets('Overscroll in both directions', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	physics: AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 20.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	expect(painter, paints..circle());
	expect(painter, isNot(paints..circle()..circle()));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, -5.0));
	expect(painter, paints..circle()..circle());

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});

	testWidgets('Overscroll horizontally', (WidgetTester tester) async {
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: CustomScrollView(
	scrollDirection: Axis.horizontal,
	physics: AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 20.0)),
	],
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(5.0, 0.0));
	expect(painter, paints..rotate(angle: math.pi / 2.0)..circle()..saveRestore());
	expect(painter, isNot(paints..circle()..circle()));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(-5.0, 0.0));
	expect(
	painter,
	paints
	..rotate(angle: math.pi / 2.0)
	..circle()
	..rotate(angle: math.pi / 2.0)
	..circle(),
	);

	await tester.pumpAndSettle(const Duration(seconds: 1));
	expect(painter, doesNotOverscroll);
	});

	testWidgets('Nested overscrolls do not throw exceptions', (WidgetTester tester) async {
	await tester.pumpWidget(Directionality(
	textDirection: TextDirection.ltr,
	child: PageView(
	children: <Widget>[
	ListView(
	children: <Widget>[
	Container(
	width: 2000.0,
	height: 2000.0,
	color: const Color(0xFF00FF00),
	),
	],
	),
	],
	),
	));

	await tester.dragFrom(const Offset(100.0, 100.0), const Offset(0.0, 2000.0));
	await tester.pumpAndSettle();
	});

	testWidgets('Changing settings', (WidgetTester tester) async {
	RenderObject painter;

	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: ScrollConfiguration(
	behavior: TestScrollBehavior1(),
	child: CustomScrollView(
	scrollDirection: Axis.horizontal,
	physics: AlwaysScrollableScrollPhysics(),
	reverse: true,
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 20.0)),
	],
	),
	),
	),
	);
	painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(5.0, 0.0));
	expect(painter, paints..rotate(angle: math.pi / 2.0)..circle(color: const Color(0x0A00FF00)));
	expect(painter, isNot(paints..circle()..circle()));

	await tester.pumpAndSettle(const Duration(seconds: 1));
	await tester.pumpWidget(
	const Directionality(
	textDirection: TextDirection.ltr,
	child: ScrollConfiguration(
	behavior: TestScrollBehavior2(),
	child: CustomScrollView(
	scrollDirection: Axis.horizontal,
	physics: AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 20.0)),
	],
	),
	),
	),
	);
	painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(5.0, 0.0));
	expect(painter, paints..rotate(angle: math.pi / 2.0)..circle(color: const Color(0x0A0000FF))..saveRestore());
	expect(painter, isNot(paints..circle()..circle()));
	});

	testWidgets('CustomScrollView overscroll indicator works if there is sliver before center', (WidgetTester tester) async {
	final Key centerKey = UniqueKey();
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ScrollConfiguration(
	behavior: const TestScrollBehavior2(),
	child: CustomScrollView(
	center: centerKey,
	physics: const AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverList(
	delegate: SliverChildBuilderDelegate(
	(BuildContext context, int index) => Text('First sliver $index'),
	childCount: 2,
	),
	),
	SliverList(
	key: centerKey,
	delegate: SliverChildBuilderDelegate(
	(BuildContext context, int index) => Text('Second sliver $index'),
	childCount: 5,
	),
	),
	],
	),
	),
	),
	);

	expect(find.text('First sliver 1'), findsNothing);

	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 300.0));
	expect(find.text('First sliver 1'), findsOneWidget);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	// The scroll offset and paint extend should cancel out each other.
	expect(painter, paints..save()..translate(y: 0.0)..scale()..circle());
	});

	testWidgets('CustomScrollView overscroll indicator works well with [CustomScrollView.center] and [OverscrollIndicatorNotification.paintOffset]', (WidgetTester tester) async {
	final Key centerKey = UniqueKey();
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: ScrollConfiguration(
	behavior: const TestScrollBehavior2(),
	child: NotificationListener<OverscrollIndicatorNotification>(
	onNotification: (OverscrollIndicatorNotification notification) {
	if (notification.leading) {
	notification.paintOffset = 50.0;
	}
	return false;
	},
	child: CustomScrollView(
	center: centerKey,
	physics: const AlwaysScrollableScrollPhysics(),
	slivers: <Widget>[
	SliverList(
	delegate: SliverChildBuilderDelegate(
	(BuildContext context, int index) => Text('First sliver $index'),
	childCount: 2,
	),
	),
	SliverList(
	key: centerKey,
	delegate: SliverChildBuilderDelegate(
	(BuildContext context, int index) => Text('Second sliver $index'),
	childCount: 5,
	),
	),
	],
	),
	),
	),
	),
	);

	expect(find.text('First sliver 1'), findsNothing);

	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0)); // offset will be magnified ten times
	expect(find.text('First sliver 1'), findsOneWidget);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	// The OverscrollIndicator should respect the [OverscrollIndicatorNotification.paintOffset] setting.
	expect(painter, paints..save()..translate(y: 50.0)..scale()..circle());
	});

	testWidgets('The OverscrollIndicator should not overflow the scrollable view edge', (WidgetTester tester) async {
	// Regressing test for https://github.com/flutter/flutter/issues/64149
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: NotificationListener<OverscrollIndicatorNotification>(
	onNotification: (OverscrollIndicatorNotification notification) {
	notification.paintOffset = 50.0; // both the leading and trailing indicator have a 50.0 pixels offset.
	return false;
	},
	child: const CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	expect(painter, paints..save()..translate(y: 50.0)..scale()..circle());
	// Reverse scroll (30 pixels), and the offset < notification.paintOffset.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -30.0));
	await tester.pump();
	// The OverscrollIndicator should move with the CustomScrollView.
	expect(painter, paints..save()..translate(y: 50.0 - 30.0)..scale()..circle());

	// Reverse scroll (30+20 pixels) and offset == notification.paintOffset.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -20.0));
	await tester.pump();
	expect(painter, paints..save()..translate(y: 50.0 - 50.0)..scale()..circle());

	// Reverse scroll (30+20+10 pixels) and offset > notification.paintOffset.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -10.0));
	await tester.pump();
	// The OverscrollIndicator should not overflow the CustomScrollView's edge.
	expect(painter, paints..save()..translate(y: 50.0 - 50.0)..scale()..circle());

	await tester.pumpAndSettle(); // Finish the leading indicator.

	// trigger the trailing indicator
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, -200.0));
	expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0)..scale()..circle());

	// Reverse scroll (30 pixels), and the offset < notification.paintOffset.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 30.0));
	await tester.pump();
	// The OverscrollIndicator should move with the CustomScrollView.
	expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 30.0)..scale()..circle());

	// Reverse scroll (30+20 pixels) and offset == notification.paintOffset.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 20.0));
	await tester.pump();
	expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 50.0)..scale()..circle());

	// Reverse scroll (30+20+10 pixels) and offset > notification.paintOffset.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 10.0));
	await tester.pump();
	// The OverscrollIndicator should not overflow the CustomScrollView's edge.
	expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 50.0)..scale()..circle());
	});

	group('[OverscrollIndicatorNotification.paintOffset] test', () {
	testWidgets('Leading', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: NotificationListener<OverscrollIndicatorNotification>(
	onNotification: (OverscrollIndicatorNotification notification) {
	if (notification.leading) {
	notification.paintOffset = 50.0;
	}
	return false;
	},
	child: const CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, 5.0));
	// The OverscrollIndicator should respect the [OverscrollIndicatorNotification.paintOffset] setting.
	expect(painter, paints..save()..translate(y: 50.0)..scale()..circle());
	// Reverse scroll direction.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, -30.0));
	await tester.pump();
	// The OverscrollIndicator should move with the CustomScrollView.
	expect(painter, paints..save()..translate(y: 50.0 - 30.0)..scale()..circle());
	});

	testWidgets('Trailing', (WidgetTester tester) async {
	await tester.pumpWidget(
	Directionality(
	textDirection: TextDirection.ltr,
	child: NotificationListener<OverscrollIndicatorNotification>(
	onNotification: (OverscrollIndicatorNotification notification) {
	if (!notification.leading) {
	notification.paintOffset = 50.0;
	}
	return false;
	},
	child: const CustomScrollView(
	slivers: <Widget>[
	SliverToBoxAdapter(child: SizedBox(height: 2000.0)),
	],
	),
	),
	),
	);
	final RenderObject painter = tester.renderObject(find.byType(CustomPaint));
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(200.0, -10000.0));
	await tester.pump();
	await slowDrag(tester, const Offset(200.0, 200.0), const Offset(0.0, -5.0));
	// The OverscrollIndicator should respect the [OverscrollIndicatorNotification.paintOffset] setting.
	expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0)..scale()..circle());
	// Reverse scroll direction.
	await tester.dragFrom(const Offset(200.0, 200.0), const Offset(0.0, 30.0));
	await tester.pump();
	// The OverscrollIndicator should move with the CustomScrollView.
	expect(painter, paints..scale(y: -1.0)..save()..translate(y: 50.0 - 30.0)..scale()..circle());
	});
	});
	}

	class TestScrollBehavior1 extends ScrollBehavior {
	const TestScrollBehavior1();

	@override
	Widget buildOverscrollIndicator(BuildContext context, Widget child, ScrollableDetails details) {
	return GlowingOverscrollIndicator(
	axisDirection: details.direction,
	color: const Color(0xFF00FF00),
	child: child,
	);
	}
	}

	class TestScrollBehavior2 extends ScrollBehavior {
	const TestScrollBehavior2();

	@override
	Widget buildOverscrollIndicator(BuildContext context, Widget child, ScrollableDetails details) {
	return GlowingOverscrollIndicator(
	axisDirection: details.direction,
	color: const Color(0xFF0000FF),
	child: child,
	);
	}
	}