import "package:flutter/material.dart";

void main() {
  ErrorWidget.builder = (FlutterErrorDetails details) {
    return Container(color: Colors.green);
  };

  runApp(const MaterialApp(home: Scaffold(body: MyApp())));
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    throw "help!";
  }
}

import 'dart:async';

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

void main() {
  // ErrorWidget.builder = (FlutterErrorDetails details) {
  //   return Material(
  //     child: Container(
  //       color: Colors.purple,
  //       alignment: Alignment.center,
  //       child: const Text(
  //         'Something went wrong!',
  //         style: TextStyle(fontSize: 20, color: Colors.white),
  //       ),
  //     ),
  //   );
  // };

  FlutterError.onError = _onError;

  runZonedGuarded<void>(() async {
    runApp(const MyApp());
  },
      ((error, stack) => _onError(FlutterErrorDetails(
            exception: error,
            stack: stack,
          ))));
}

void _onError(FlutterErrorDetails details) {
  WidgetsBinding.instance.addPostFrameCallback(
    (timeStamp) {
      showDialog(
        context: MyApp.navigatorKey.currentContext!,
        builder: (b) {
          return Padding(
            padding: const EdgeInsets.all(20.0),
            child: GestureDetector(
              onTap: () {
                Navigator.of(b).pop();
              },
              child: Material(
                child: Container(
                  padding: EdgeInsets.all(10),
                  child: SingleChildScrollView(
                      child: Column(
                    children: <Widget>[
                      Text('exception:'),
                      Text('${details.exception}'),
                      Text('stack:'),
                      Text('${details.stack}'),
                    ],
                  )),
                ),
              ),
            ),
          );
        },
      );
    },
  );
}

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

  static GlobalKey<NavigatorState> navigatorKey = GlobalKey<NavigatorState>();

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      navigatorKey: navigatorKey,
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

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

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Stack(children: <Widget>[
        GestureDetector(
          child: Positioned(
            child: Container(
              height: 10,
              width: 10,
              color: Colors.red,
            ),
          ),
        )
      ]),

      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}