扑扑定时器结束时如何触发对话框

Question

当controller.value == 0时，我试图触发showDialog（）。我在GestureDetecter中尝试了相同的对话框，并且运行良好。但是当我在计时器结束时触发它时，会显示此错误..在构建过程中调用setState（）或markneedsbuild（）。我从https://www.didierboelens.com/faq/week2/这篇文章中知道发生这种情况的原因，但我不知道如何解决此问题。因为我需要在计时器达到0.00时显示showDialog。

envs []string = runtime_envs()

再次，我知道发生这种情况的原因，我只是不知道如何实现这一目标。

Answer 1

尝试一下：

  AnimatedBuilder(
    animation: controller,
      builder: (BuildContext context, Widget child) {                            
        return controller.value == 0? autoSubmition() : Container();
      },
  ),//shows this error setState() or markneedsbuild() called during build error

  autoSubmition() {
    //model.setTestTimerRunning(false);
    var autoResponse = {
      "submitDialogTitle":
          "You're have ran out of time. Please Submit your answer",
      "submitDialogSubtitle":
          "If you cancel this test will be terminated. Your score will be reset to zero"
    };

// Wrap showDialog inside the widgetsBinding

    WidgetsBinding.instance
            .addPostFrameCallback((_) => showDialog(
      context: context,
      barrierDismissible: false,
      builder: (_) {
        return AutoSubmitTestDialog(
            context: context,
            model: model,
            testItem: testItem,
            messages: autoResponse);
      },
    ));
  }

Answer 2

您可以在下面复制粘贴运行完整代码
如果0的意思是AnimationStatus.completed，则您可以收听此事件并弹出对话框

代码段

controller =
        AnimationController(duration: const Duration(seconds: 10), vsync: this);

    controller.addStatusListener(((status) {
      if (status == AnimationStatus.completed) {
        print("completed");
        _neverSatisfied();

演示

完整代码

import 'package:flutter/material.dart';

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(
        // 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: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, 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
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> with SingleTickerProviderStateMixin {
  int _counter = 0;
  AnimationController controller;
  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();
    controller =
        AnimationController(duration: const Duration(seconds: 10), vsync: this);

    controller.addStatusListener(((status) {
      if (status == AnimationStatus.completed) {
        print("completed");
        _neverSatisfied();
      } else if (status == AnimationStatus.dismissed) {
        //controller.forward();
      }
    }));

    controller.forward();
  }

  Future<void> _neverSatisfied() async {
    return showDialog<void>(
      context: context,
      barrierDismissible: false, // user must tap button!
      builder: (BuildContext context) {
        return AlertDialog(
          title: Text('Rewind and remember'),
          content: SingleChildScrollView(
            child: ListBody(
              children: <Widget>[
                Text('You will never be satisfied.'),
                Text('You\’re like me. I’m never satisfied.'),
              ],
            ),
          ),
          actions: <Widget>[
            FlatButton(
              child: Text('Regret'),
              onPressed: () {
                Navigator.of(context).pop();
              },
            ),
          ],
        );
      },
    );
  }

  @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: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            AnimatedBuilder(
              animation: controller,
              builder: (BuildContext context, Widget child) {
                return controller.value == 0? Text("0") : Text("Run");
              },
            ),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}