Added a NavgationBar example with nested Navigators (#98440)

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Hans Muller 2022-02-15 13:28:47 -08:00 committed by GitHub
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// 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.
// Flutter code sample for NavigationBar with nested Navigator destinations.
import 'package:flutter/material.dart';
class Destination {
const Destination(this.index, this.title, this.icon, this.color);
final int index;
final String title;
final IconData icon;
final MaterialColor color;
}
class RootPage extends StatelessWidget {
const RootPage({ Key? key, required this.destination }) : super(key: key);
final Destination destination;
Widget _buildDialog(BuildContext context) {
return AlertDialog(
title: Text('${destination.title} AlertDialog'),
actions: <Widget>[
TextButton(
onPressed: () { Navigator.pop(context); },
child: const Text('OK'),
),
],
);
}
@override
Widget build(BuildContext context) {
final TextStyle headline5 = Theme.of(context).textTheme.headline5!;
final ButtonStyle buttonStyle = ElevatedButton.styleFrom(
primary: destination.color,
visualDensity: VisualDensity.comfortable,
padding: const EdgeInsets.symmetric(vertical: 12, horizontal: 16),
textStyle: headline5,
);
return Scaffold(
appBar: AppBar(
title: Text('${destination.title} RootPage - /'),
backgroundColor: destination.color,
),
backgroundColor: destination.color[50],
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
ElevatedButton(
style: buttonStyle,
onPressed: () {
Navigator.pushNamed(context, '/list');
},
child: const Text('Push /list'),
),
const SizedBox(height: 16),
ElevatedButton(
style: buttonStyle,
onPressed: () {
showDialog(
context: context,
useRootNavigator: false,
builder: _buildDialog,
);
},
child: const Text('Local Dialog'),
),
const SizedBox(height: 16),
ElevatedButton(
style: buttonStyle,
onPressed: () {
showDialog(
context: context,
useRootNavigator: true,
builder: _buildDialog,
);
},
child: const Text('Root Dialog'),
),
const SizedBox(height: 16),
Builder(
builder: (BuildContext context) {
return ElevatedButton(
style: buttonStyle,
onPressed: () {
showBottomSheet(
context: context,
builder: (BuildContext context) {
return Container(
padding: const EdgeInsets.all(16),
width: double.infinity,
child: Text(
'${destination.title} BottomSheet\n'
'Tap the back button to dismiss',
style: headline5,
softWrap: true,
textAlign: TextAlign.center,
),
);
},
);
},
child: const Text('Local BottomSheet'),
);
},
),
],
),
),
);
}
}
class ListPage extends StatelessWidget {
const ListPage({ Key? key, required this.destination }) : super(key: key);
final Destination destination;
@override
Widget build(BuildContext context) {
const int itemCount = 50;
final ButtonStyle buttonStyle = OutlinedButton.styleFrom(
primary: destination.color,
fixedSize: const Size.fromHeight(128),
textStyle: Theme.of(context).textTheme.headline5,
);
return Scaffold(
appBar: AppBar(
title: Text('${destination.title} ListPage - /list'),
backgroundColor: destination.color,
),
backgroundColor: destination.color[50],
body: SizedBox.expand(
child: ListView.builder(
itemCount: itemCount,
itemBuilder: (BuildContext context, int index) {
return Padding(
padding: const EdgeInsets.symmetric(vertical: 4, horizontal: 8),
child: OutlinedButton(
style: buttonStyle.copyWith(
backgroundColor: MaterialStateProperty.all<Color>(
Color.lerp(destination.color[100], Colors.white, index / itemCount)!
),
),
onPressed: () {
Navigator.pushNamed(context, '/text');
},
child: Text('Push /text [$index]'),
),
);
},
),
),
);
}
}
class TextPage extends StatefulWidget {
const TextPage({ Key? key, required this.destination }) : super(key: key);
final Destination destination;
@override
State<TextPage> createState() => _TextPageState();
}
class _TextPageState extends State<TextPage> {
late final TextEditingController textController;
@override
void initState() {
super.initState();
textController = TextEditingController(text: 'Sample Text');
}
@override
void dispose() {
textController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
final ThemeData theme = Theme.of(context);
return Scaffold(
appBar: AppBar(
title: Text('${widget.destination.title} TextPage - /list/text'),
backgroundColor: widget.destination.color,
),
backgroundColor: widget.destination.color[50],
body: Container(
padding: const EdgeInsets.all(32.0),
alignment: Alignment.center,
child: TextField(
controller: textController,
style: theme.primaryTextTheme.headline4?.copyWith(
color: widget.destination.color,
),
decoration: InputDecoration(
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(
color: widget.destination.color,
width: 3.0,
),
),
),
),
),
);
}
}
class DestinationView extends StatefulWidget {
const DestinationView({
Key? key,
required this.destination,
required this.navigatorKey,
}) : super(key: key);
final Destination destination;
final Key navigatorKey;
@override
State<DestinationView> createState() => _DestinationViewState();
}
class _DestinationViewState extends State<DestinationView> {
@override
Widget build(BuildContext context) {
return Navigator(
key: widget.navigatorKey,
onGenerateRoute: (RouteSettings settings) {
return MaterialPageRoute<void>(
settings: settings,
builder: (BuildContext context) {
switch(settings.name) {
case '/':
return RootPage(destination: widget.destination);
case '/list':
return ListPage(destination: widget.destination);
case '/text':
return TextPage(destination: widget.destination);
}
assert(false);
return const SizedBox();
},
);
},
);
}
}
class Home extends StatefulWidget {
const Home({ Key? key }) : super(key: key);
@override
State<Home> createState() => _HomeState();
}
class _HomeState extends State<Home> with TickerProviderStateMixin<Home> {
static const List<Destination> allDestinations = <Destination>[
Destination(0, 'Teal', Icons.home, Colors.teal),
Destination(1, 'Cyan', Icons.business, Colors.cyan),
Destination(2, 'Orange', Icons.school, Colors.orange),
Destination(3, 'Blue', Icons.flight, Colors.blue)
];
late final List<GlobalKey<NavigatorState>> navigatorKeys;
late final List<GlobalKey> destinationKeys;
late final List<AnimationController> destinationFaders;
late final List<Widget> destinationViews;
int selectedIndex = 0;
AnimationController buildFaderController() {
final AnimationController controller = AnimationController(vsync: this, duration: const Duration(milliseconds: 200));
controller.addStatusListener((AnimationStatus status) {
if (status == AnimationStatus.dismissed) {
setState(() { }); // Rebuild unselected destinations offstage.
}
});
return controller;
}
@override
void initState() {
super.initState();
navigatorKeys = List<GlobalKey<NavigatorState>>.generate(allDestinations.length, (int index) => GlobalKey()).toList();
destinationFaders = List<AnimationController>.generate(allDestinations.length, (int index) => buildFaderController()).toList();
destinationFaders[selectedIndex].value = 1.0;
destinationViews = allDestinations.map((Destination destination) {
return FadeTransition(
opacity: destinationFaders[destination.index].drive(CurveTween(curve: Curves.fastOutSlowIn)),
child: KeyedSubtree(
key: GlobalKey(),
child: DestinationView(
destination: destination,
navigatorKey: navigatorKeys[destination.index],
),
)
);
}).toList();
}
@override
void dispose() {
for (final AnimationController controller in destinationFaders) {
controller.dispose();
}
super.dispose();
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async {
final NavigatorState navigator = navigatorKeys[selectedIndex].currentState!;
if (!navigator.canPop()) {
return true;
}
navigator.pop();
return false;
},
child: Scaffold(
body: SafeArea(
top: false,
child: Stack(
fit: StackFit.expand,
children: allDestinations.map((Destination destination) {
final int index = destination.index;
final Widget view = destinationViews[index];
if (index == selectedIndex) {
destinationFaders[index].forward();
return Offstage(offstage: false, child: view);
} else {
destinationFaders[index].reverse();
if (destinationFaders[index].isAnimating) {
return IgnorePointer(child: view);
}
return Offstage(child: view);
}
}).toList(),
),
),
bottomNavigationBar: NavigationBar(
selectedIndex: selectedIndex,
onDestinationSelected: (int index) {
setState(() {
selectedIndex = index;
});
},
destinations: allDestinations.map((Destination destination) {
return NavigationDestination(
icon: Icon(destination.icon, color: destination.color),
label: destination.title,
);
}).toList(),
),
),
);
}
}
void main() {
runApp(const MaterialApp(home: Home()));
}

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// 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 'package:flutter/material.dart';
import 'package:flutter_api_samples/material/navigation_bar/navigation_bar.0.dart' as example;
import 'package:flutter_test/flutter_test.dart';
void main() {
testWidgets('RootPage: only selected destination is on stage', (WidgetTester tester) async {
await tester.pumpWidget(const MaterialApp(home: example.Home()));
const String tealTitle = 'Teal RootPage - /';
const String cyanTitle = 'Cyan RootPage - /';
const String orangeTitle = 'Orange RootPage - /';
const String blueTitle = 'Blue RootPage - /';
await tester.tap(find.widgetWithText(NavigationDestination, 'Teal'));
await tester.pumpAndSettle();
expect(find.text(tealTitle), findsOneWidget);
expect(find.text(cyanTitle), findsNothing);
expect(find.text(orangeTitle), findsNothing);
expect(find.text(blueTitle), findsNothing);
await tester.tap(find.widgetWithText(NavigationDestination, 'Cyan'));
await tester.pumpAndSettle();
expect(find.text(tealTitle), findsNothing);
expect(find.text(cyanTitle), findsOneWidget);
expect(find.text(orangeTitle), findsNothing);
expect(find.text(blueTitle), findsNothing);
await tester.tap(find.widgetWithText(NavigationDestination, 'Orange'));
await tester.pumpAndSettle();
expect(find.text(tealTitle), findsNothing);
expect(find.text(cyanTitle), findsNothing);
expect(find.text(orangeTitle), findsOneWidget);
expect(find.text(blueTitle), findsNothing);
await tester.tap(find.widgetWithText(NavigationDestination, 'Blue'));
await tester.pumpAndSettle();
expect(find.text(tealTitle), findsNothing);
expect(find.text(cyanTitle), findsNothing);
expect(find.text(orangeTitle), findsNothing);
expect(find.text(blueTitle), findsOneWidget);
});
testWidgets('RootPage', (WidgetTester tester) async {
await tester.pumpWidget(const MaterialApp(home: example.Home()));
await tester.tap(find.widgetWithText(NavigationDestination, 'Teal'));
await tester.pumpAndSettle();
await tester.tap(find.text('Local Dialog'));
await tester.pumpAndSettle();
expect(find.text('Teal AlertDialog'), findsOneWidget);
await tester.tap(find.text('OK'));
await tester.pumpAndSettle();
expect(find.text('Teal AlertDialog'), findsNothing);
await tester.pumpAndSettle();
await tester.tap(find.text('Root Dialog'));
await tester.pumpAndSettle();
expect(find.text('Teal AlertDialog'), findsOneWidget);
await tester.tapAt(const Offset(5, 5));
await tester.pumpAndSettle();
expect(find.text('Teal AlertDialog'), findsNothing);
await tester.tap(find.text('Local BottomSheet'));
await tester.pumpAndSettle();
expect(find.byType(BottomSheet), findsOneWidget);
await tester.tap(find.byType(BackButton));
await tester.pumpAndSettle();
expect(find.byType(BottomSheet), findsNothing);
await tester.tap(find.text('Push /list'));
await tester.pumpAndSettle();
expect(find.text('Teal ListPage - /list'), findsOneWidget);
});
testWidgets('ListPage', (WidgetTester tester) async {
await tester.pumpWidget(const MaterialApp(home: example.Home()));
expect(find.text('Teal RootPage - /'), findsOneWidget);
await tester.tap(find.widgetWithText(ElevatedButton, 'Push /list'));
await tester.pumpAndSettle();
expect(find.text('Teal ListPage - /list'), findsOneWidget);
expect(find.text('Push /text [0]'), findsOneWidget);
await tester.tap(find.widgetWithText(NavigationDestination, 'Orange'));
await tester.pumpAndSettle();
await tester.tap(find.widgetWithText(ElevatedButton, 'Push /list'));
await tester.pumpAndSettle();
expect(find.text('Orange ListPage - /list'), findsOneWidget);
expect(find.text('Push /text [0]'), findsOneWidget);
await tester.tap(find.byType(BackButton));
await tester.pumpAndSettle();
expect(find.text('Orange RootPage - /'), findsOneWidget);
await tester.tap(find.widgetWithText(NavigationDestination, 'Teal'));
await tester.pumpAndSettle();
expect(find.text('Teal ListPage - /list'), findsOneWidget);
await tester.tap(find.byType(BackButton));
await tester.pumpAndSettle();
expect(find.text('Teal RootPage - /'), findsOneWidget);
});
}

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@ -59,6 +59,21 @@ import 'tooltip.dart';
/// ),
/// ),
/// ```
///
/// {@tool dartpad}
/// This example has a [NavigationBar] where each destination has its
/// own Navigator, Scaffold, and Appbar. That means that each
/// destination has an independent route history and (app bar) back
/// button. A [Stack] is used to display one destination at a time and
/// destination changes are handled by cross fade transitions. Destinations
/// that have been completely faded out are [Offstage].
///
/// One can see that the appearance of each destination's dialogs, bottom sheet,
/// list scrolling state, and text field state, persist when another destination
/// is selected.
///
/// ** See code in examples/api/lib/material/navigation_bar/navigation_bar.0.dart **
/// {@end-tool}
class NavigationBar extends StatelessWidget {
/// Creates a Material 3 Navigation Bar component.
///