如何检查AnimatedContainer是否完全处于动画状态？

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

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

class _MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
  AnimationController _controller;
  bool _isAnimating = false;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: Duration(seconds: 2),
      vsync: this,
    );
    _controller.addStatusListener((status) {
      if (status == AnimationStatus.forward ||
          status == AnimationStatus.reverse) {
        setState(() {
          _isAnimating = true;
        });
      } else {
        setState(() {
          _isAnimating = false;
        });
      }
    });
    _controller.forward();
  }

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('AnimatedContainer Demo'),
        ),
        body: Center(
          child: AnimatedContainer(
            duration: Duration(seconds: 2),
            width: _isAnimating ? 200.0 : 100.0,
            height: _isAnimating ? 200.0 : 100.0,
            color: _isAnimating ? Colors.red : Colors.blue,
          ),
        ),
      ),
    );
  }
}