带有动画子对象大小的Flutter PageView.builder

import 'package:flutter/material.dart';

class AnimatedPage extends StatefulWidget {
  @override
  _AnimatedPageState createState() => _AnimatedPageState();
}

class _AnimatedPageState extends State<AnimatedPage>
    with SingleTickerProviderStateMixin {
  AnimationController _controller;
  Animation<double> _animation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: Duration(seconds: 1),
      vsync: this,
    );
    _animation = Tween<double>(begin: 100, end: 200).animate(_controller);
    _controller.forward();
  }

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Animated Page'),
      ),
      body: Center(
        child: PageView.builder(
          itemCount: 3,
          itemBuilder: (context, index) {
            return AnimatedBuilder(
              animation: _animation,
              builder: (context, child) {
                return Container(
                  width: _animation.value,
                  height: _animation.value,
                  color: Colors.blue,
                  child: Center(
                    child: Text(
                      'Page ${index + 1}',
                      style: TextStyle(
                        fontSize: 20,
                        color: Colors.white,
                      ),
                    ),
                  ),
                );
              },
            );
          },
        ),
      ),
    );
  }
}