Locked screen or dialogue in Flutter-CodePudding

Is it possible to lock the screen or dialogue so that the user cannot go back to the previous screen until some action is performed, e.g. until the internet returns?

CodePudding user response：

You can use WillPopScope widget and check a condition and decide to pop the screen or not

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: _title,
      home: MyStatefulWidget(),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  bool shouldPop = true;
  @override
  Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: () async {
        return shouldPop;
      },
      child: Scaffold(
        appBar: AppBar(
          title: const Text('Flutter WillPopScope demo'),
        ),
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              OutlinedButton(
                child: const Text('Push'),
                onPressed: () {
                  Navigator.of(context).push<void>(
                    MaterialPageRoute<void>(
                      builder: (BuildContext context) {
                        return const MyStatefulWidget();
                      },
                    ),
                  );
                },
              ),
              OutlinedButton(
                child: Text('shouldPop: $shouldPop'),
                onPressed: () {
                  setState(
                    () {
                      shouldPop = !shouldPop;
                    },
                  );
                },
              ),
              const Text('Push to a new screen, then tap on shouldPop '
                  'button to toggle its value. Press the back '
                  'button in the appBar to check its behavior '
                  'for different values of shouldPop'),
            ],
          ),
        ),
      ),
    );
  }
}

In case of alert dialog you can use

barrierDismissible : false,