我复制粘贴了VideoPlayer package的例子但是在网页上没有全屏，我该怎么解决这个问题呢？

示例代码

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

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  late VideoPlayerController _controller;

  @override
  void initState() {
    super.initState();
    _controller = VideoPlayerController.network(
        'https://assets.mixkit.co/videos/preview/mixkit-womans-hands-decorating-a-handmade-soap-2803-large.mp4')
      ..initialize().then((_) {
        // Ensure the first frame is shown after the video is initialized, even before the play button has been pressed.
        setState(() {});
      })
      ..play()
      ..setLooping(true);
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Video Demo',
      home: Scaffold(
        body: _controller.value.isInitialized
            ? AspectRatio(
                aspectRatio: _controller.value.aspectRatio,
                child: VideoPlayer(_controller),
              )
            : Container(),
      ),
    );
  }

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

输出