在我的第一个颤振应用程序中,我有一个材质设计的导航抽屉。这项工作很好,但是在使用WillPopScope
显示AlertDialog
时,我找不到任何方法可以关闭“后退按钮”上的导航抽屉是否打开。该应用程序仅显示AlertDialog
而不是在按下时关闭抽屉。我希望抽屉应该在已经打开的情况下关闭,否则显示AlertDialog
。
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: onBackPressed,
child: Scaffold(
appBar: AppBar(
title: Text("Home"),
),
drawer: Drawer(
),
body: Center(
child: Text("Home"),
),
),
);
}
onBackPressed 显示对话框以关闭应用程序。
Future<bool> onBackPressed() {
return showDialog(
barrierDismissible: false,
context: context,
builder: (context) => AlertDialog(
title: Text("Do you want to exit?"),
actions: <Widget>[
FlatButton(
onPressed: () => Navigator.pop(context, false),
child: Text("No")),
FlatButton(
onPressed: () => Navigator.pop(context, true),
child: Text("Yes"))
],
));
}
有人可以指导我如何实现这一目标吗?
答案 0 :(得分:8)
您可以在下面复制粘贴运行完整代码
步骤1:您需要脚手架钥匙来控制抽屉,所以您需要GlobalKey<ScaffoldState> _key = new GlobalKey<ScaffoldState>();
步骤2:在onWillPop
中,您可以检查isDrawerOpen
并执行Navigator.pop
代码段
GlobalKey<ScaffoldState> _key = new GlobalKey<ScaffoldState>();
MyHomePage({Key key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async {
if (_key.currentState.isDrawerOpen) {
Navigator.of(context).pop();
return false;
}
return true;
},
child: Scaffold(
工作演示
完整代码
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async {
print("My App Page");
//return false;
},
child: MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: "test",),
),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
GlobalKey<ScaffoldState> _key = new GlobalKey<ScaffoldState>();
MyHomePage({Key key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async {
if (_key.currentState.isDrawerOpen) {
Navigator.of(context).pop();
return false;
}
return true;
},
child: Scaffold(
key: _key,
appBar: AppBar(title: Text(title)),
body: Center(child: Text('My Page!')),
drawer: Drawer(
child: ListView(
padding: EdgeInsets.zero,
children: <Widget>[
DrawerHeader(
child: Text('Drawer Header'),
decoration: BoxDecoration(
color: Colors.blue,
),
),
ListTile(
title: Text('page 2'),
onTap: () {
Navigator.push(
context, new MaterialPageRoute(builder: (context) => Page2()));
},
),
ListTile(
title: Text('Item 2'),
onTap: () {
// Update the state of the app
// ...
// Then close the drawer
Navigator.pop(context);
},
),
],
),
),
),
);
}
}
class Page2 extends StatelessWidget {
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async {
print("Page2");
_popNavigationWithResult(context, 'from_back');
return false;
},
child: Scaffold(
floatingActionButton: FloatingActionButton(
onPressed: () {
_popNavigationWithResult(context, 'from_button');
},
),
body: Container(
child: Center(
child: Text('Page 2',
style: TextStyle(fontSize: 30.0, fontWeight: FontWeight.bold)),
),
),
),
);
}
void _popNavigationWithResult(BuildContext context, dynamic result) {
Navigator.pop(context, result);
}
}