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

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

class MyApp extends StatefulWidget {
  @override
  MyAppState createState() => MyAppState();
}

class MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
  Animation animation;
  AnimationController animationController;

  @override
  void initState() {
    super.initState();
    animationController = AnimationController(
        duration: Duration(milliseconds: 2000), vsync: this);

    animation = Tween(begin: 0.0, end: 400.0).animate(animationController);
    animation.addStatusListener((status) {
      if (status == AnimationStatus.completed) {
        animationController.reverse();
      } else if (status == AnimationStatus.dismissed) {
        animationController.forward();
      }
    });
    animationController.forward();
  }

  @override
  Widget build(BuildContext context) {
    return LogoAnimation(
      animation: animation,
    );
  }

  @override
  void dispose() {
    animationController.dispose();
    super.dispose();
  }
}

class LogoAnimation extends AnimatedWidget {
  LogoAnimation({Key key, Animation animation})
      : super(key: key, listenable: animation);

  @override
  Widget build(BuildContext context) {
    Animation animation = listenable;
    return Center(
      child: Container(
        height: animation.value,
        width: animation.value,
        child: FlutterLogo(),
      ),
    );
  }
}