如何在Flutter中设置文本下划线的动画？

import 'package:flutter/material.dart';

class AnimatedUnderlineText extends StatefulWidget {
  @override
  _AnimatedUnderlineTextState createState() => _AnimatedUnderlineTextState();
}

class _AnimatedUnderlineTextState extends State<AnimatedUnderlineText>
    with SingleTickerProviderStateMixin {
  AnimationController _controller;
  Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: Duration(seconds: 1),
      vsync: this,
    );
    _animation = Tween<double>(begin: 0, end: 1).animate(_controller);
    _controller.repeat(reverse: true);
  }

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

  @override
  Widget build(BuildContext context) {
    return AnimatedBuilder(
      animation: _animation,
      builder: (context, child) {
        return Text(
          'Animated Underline',
          style: TextStyle(
            decoration: TextDecoration.underline,
            decorationThickness: 2.0,
            decorationColor: Colors.blue,
            decorationStyle: TextDecorationStyle.solid,
            foreground: Paint()
              ..shader = LinearGradient(
                colors: [Colors.blue, Colors.green],
              ).createShader(
                Rect.fromLTWH(0, 0, 200, 0),
              ),
          ),
        );
      },
    );
  }
}

// 使用示例
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Animated Underline Text'),
        ),
        body: Center(
          child: AnimatedUnderlineText(),
        ),
      ),
    );
  }
}