flutter显示dialog的问题

要自动显示一个dialog，但是，有动画在运行，不断地调用setstate，然后调用build，最终导致直接背景成为黑色的，dialog也在不断重构

解决方法是显示dialog的时候让动画暂停

import 'package:flutter/material.dart';
import 'dart:async';
import 'package:flutter_localizations/flutter_localizations.dart';

void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new 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 press Run > Flutter Hot Reload in IntelliJ). Notice that the
        // counter didn't reset back to zero; the application is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}
class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State
    with SingleTickerProviderStateMixin {
  int _counter = 0;
  AnimationController animationController;
  Animation animation;
  bool showing=false;
  bool first=true;
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    animationController = new AnimationController(
        vsync: this, duration: Duration(milliseconds: 3000));
    animation = Tween(begin: 1.0, end: 2.0).animate(CurvedAnimation(
        parent: animationController, curve: Curves.fastOutSlowIn))
      ..addStatusListener((status) {
        if (status == AnimationStatus.completed) {
          animationController.reverse();
        }
        if (status == AnimationStatus.dismissed) {
          animationController.forward();
        }
      })
      ..addListener(() {
      if (!showing){
        setState(() {});
      }
      //  setState(() {});
      });
    animationController.repeat();
    print("rrrrrrrrrrrrrrrrr");
  }

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }
@override
  void setState(fn) {
    // TODO: implement setState
    super.setState(fn);
    print("ppppppppppppppp");
  }

  @override
  void didUpdateWidget(MyHomePage oldWidget) {
    // TODO: implement didUpdateWidget
    super.didUpdateWidget(oldWidget);
    print("11111111111111");
  }
  @override
  Widget build(BuildContext context) {
    print("22222222222222");
    if(first==true){
      Future.delayed(Duration.zero, () => showMyDialog(context));
      first=false;
    }

    return new MaterialApp(
//        localizationsDelegates: [
//          // ... app-specific localization delegate[s] here
//          GlobalMaterialLocalizations.delegate,
//          GlobalWidgetsLocalizations.delegate,
//        ],
//        supportedLocales: [
//          const Locale('zh', 'CH'),
//        ],

        home: new Scaffold(
      body: new Center(
          child: new Stack(
        children: [
          Transform.translate(
            offset: Offset(animation.value, animation.value),
            child: Image.asset(
              "assets/cute1.jpg",
              width: 21.0,
              height: 21.0,
              fit: BoxFit.fill,
            ),
          ),
          Transform.translate(
            offset: Offset(animation.value * 2, animation.value * 2),
            child: Image.asset(
              "assets/add.png",
              width: 21.0,
              height: 21.0,
              fit: BoxFit.fill,
            ),
          ),
//            new RaisedButton(
//                child: new Text('提交'),
//                onPressed: () {
//                  showMyDialog(context);
//                }
//            )
        ],
      )),
      floatingActionButton: new FloatingActionButton(
        onPressed: (){showMyDialog(context);},
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.


        ));
    // return
  }

  void showMyDialog(BuildContext context) {
    showing=true;
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(

            content: const Text(
              'Message',
            ),
            actions: [
              FlatButton(
                child: const Text('OK'),
                onPressed: () {
                  Navigator.of(context).pop(true);
                  showing=false;
                },
              ),
            ],


        );

//      return new SimpleDialog(
//        title: new Text('Test'),
//        children: [
//          new RadioListTile(
//            title: new Text('Testing'), value: null, groupValue: null, onChanged: (value) {},
//          )
//        ],
//      );
       // return
      },
    );
  }
}