使用动画颤动使TextField动态变大？

import 'package:flutter/material.dart';

class TextFieldShakeAnimation extends StatefulWidget {
  @override
  _TextFieldShakeAnimationState createState() => _TextFieldShakeAnimationState();
}

class _TextFieldShakeAnimationState extends State<TextFieldShakeAnimation> with SingleTickerProviderStateMixin {
  AnimationController _animationController;
  Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _animationController = AnimationController(
      duration: const Duration(milliseconds: 500),
      vsync: this,
    );

    _animation = Tween<double>(begin: 0, end: 10).animate(
      CurvedAnimation(parent: _animationController, curve: Curves.easeInOut),
    );
  }

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

  void _startAnimation() {
    _animationController.reset();
    _animationController.forward();
  }

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _animation,
      builder: (BuildContext context, Widget child) {
        return Container(
          margin: EdgeInsets.only(bottom: _animation.value),
          child: TextField(
            decoration: InputDecoration(
              hintText: 'Enter text',
              border: OutlineInputBorder(),
            ),
          ),
        );
      },
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(title: Text('TextField Shake Animation')),
      body: Center(
        child: TextFieldShakeAnimation(),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.play_arrow),
        onPressed: () {
          TextFieldShakeAnimationState()._startAnimation();
        },
      ),
    ),
  ));
}