Flutter Image Picker强制用户拍摄视频而不是照片

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

class CameraScreen extends StatefulWidget {
  @override
  _CameraScreenState createState() => _CameraScreenState();
}

class _CameraScreenState extends State<CameraScreen> {
  CameraController _controller;
  List<CameraDescription> _cameras;

  @override
  void initState() {
    super.initState();
    _initializeCamera();
  }

  void _initializeCamera() async {
    _cameras = await availableCameras();
    _controller = CameraController(_cameras[0], ResolutionPreset.high);
    await _controller.initialize();
    if (!mounted) {
      return;
    }
    setState(() {});
  }

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

  void _startVideoRecording() async {
    if (!_controller.value.isRecordingVideo) {
      final path = 'path_to_save_video';
      await _controller.startVideoRecording(path);
    }
  }

  void _stopVideoRecording() async {
    if (_controller.value.isRecordingVideo) {
      await _controller.stopVideoRecording();
    }
  }

  @override
  Widget build(BuildContext context) {
    if (!_controller.value.isInitialized) {
      return Container();
    }
    return Scaffold(
      appBar: AppBar(
        title: Text('Camera Screen'),
      ),
      body: AspectRatio(
        aspectRatio: _controller.value.aspectRatio,
        child: CameraPreview(_controller),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _startVideoRecording,
        child: Icon(Icons.videocam),
      ),
    );
  }
}