Flutter 中不可关闭的对话框

如何解决Flutter 中不可关闭的对话框

我想要实现的是通过单击android中的后退按钮来制作无法关闭的对话框。

我知道 barrierdismissible 方法的 showDialog 属性，但它只执行名称所暗示的操作。将其设置为 false 并单击后退按钮，对话框仍然消失。

我还尝试将我的代码包装在 WillPopScope 中以拦截后退按钮点击，但如果显示对话框，则永远不会调用 onWillPop。也许我搞砸了 context 或其他东西，或者有另一种方法来实现这种行为？任何帮助表示赞赏。

我稍微修改了默认计数器应用程序以显示我的研究目前处于哪个阶段

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',theme: ThemeData(
        primarySwatch: Colors.blue,),home: MyHomePage(title: 'Flutter Demo Home Page'),);
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key,this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  bool _isLocationWarningActive = false;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: () async {
        // this is never called if the dialog is shown
        if (_isLocationWarningActive) return true;
        return false;
      },child: Scaffold(
        appBar: AppBar(
          title: Text(widget.title),body: Center(
          child: LocationChecker(
            isLocationWarningActive: _isLocationWarningActive,setIsLocationWarningActive: (value) {
              setState(() {
                _isLocationWarningActive = value;
              });
            },child: Column(
              mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
                Text(
                  'You have pushed the button this many times:',Text(
                  '$_counter',style: Theme.of(context).textTheme.headline4,],floatingActionButton: FloatingActionButton(
          onpressed: _incrementCounter,tooltip: 'Increment',child: Icon(Icons.add),// This trailing comma makes auto-formatting nicer for build methods.
      ),);
  }
}

class LocationChecker extends StatefulWidget {
  final bool isLocationWarningActive;
  final Function(bool) setIsLocationWarningActive;
  final Widget child;

  const LocationChecker({Key key,this.setIsLocationWarningActive,this.isLocationWarningActive,this.child}) : super(key: key);
  
  @override
  _LocationCheckerState createState() => _LocationCheckerState();
}

class _LocationCheckerState extends State<LocationChecker> with WidgetsBindingObserver {
  
  @override
  void initState() {
    WidgetsBinding.instance.addobserver(this);
    super.initState();
  }
  
  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }
  
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    print("state: $state");
    if (state == AppLifecycleState.resumed && !_isCheckingLocation) {
      _showLocationSettingsAlertIfNeeded();
    }
  }

  bool _isCheckingLocation = false;
  Future _showLocationSettingsAlertIfNeeded() async {
    if (!mounted) return;
    _isCheckingLocation = true;
  
    if (await checkLocationPermission) {
      if (widget.isLocationWarningActive) {
        widget.setIsLocationWarningActive(false);
        _isCheckingLocation = false;
        Navigator.of(context).pop(true);
      }
    } else if (!widget.isLocationWarningActive) {
      print("should show notification");
      widget.setIsLocationWarningActive(true);
      await showDialog(
        context: context,barrierdismissible: false,builder: (BuildContext context) =>
            OneActionDialog(
              title: "Location Settings",child: Text("Click OK to goto settings"),btnTitle: "OK",action: () {
                widget.setIsLocationWarningActive(false);
                _isCheckingLocation = false;
                SystemSetting.goto(SettingTarget.LOCATION);
                Navigator.of(context).pop(true);
              },);
    }
  }
  
  @override
  Widget build(BuildContext context) {
    return Container(
      child: widget.child,);
  }
}

Future<bool> get checkLocationPermission async {
  ServiceStatus serviceStatus = await LocationPermissions().checkServiceStatus();
  if (serviceStatus != ServiceStatus.enabled) return false;
  final access = await LocationPermissions().checkPermissionStatus();
  switch (access) {
    case PermissionStatus.unkNown:
    case PermissionStatus.denied:
    case PermissionStatus.restricted:
      final permission = await LocationPermissions().requestPermissions(
        permissionLevel: LocationPermissionLevel.locationAlways,);
      if (permission == PermissionStatus.granted) {
        return true;
      } else {
        return false;
      }
      break;
    case PermissionStatus.granted:
      return true;
      break;
    default:
      return false;
      break;
  }
}