可以在没有预览和用户交互的情况下拍照吗

我需要在flutter中创建一个在线考试应用程序，在那里我们需要每隔一段时间拍摄用户的照片和视频，在这样做的同时，我们不想显示相机屏幕。

我试着使用flutter的相机插件，我可以拍照，但我找不到任何方法在没有相机预览的情况下捕捉图像

这是我的代码

import 'dart:async';
import 'dart:io';
import 'package:camera/camera.dart';
import 'package:flutter/material.dart';
import 'package:path/path.dart' show join;
import 'package:path_provider/path_provider.dart';
import 'package:countdown_flutter/countdown_flutter.dart';
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
// Obtain a list of the available cameras on the device.
final cameras = await availableCameras();
// Get a specific camera from the list of available cameras.
final firstCamera = cameras.first;
final frontCam = cameras[1];
runApp(
MaterialApp(
theme: ThemeData.dark(),
home: TakePictureScreen(
// Pass the appropriate camera to the TakePictureScreen widget.
camera: frontCam,
),
),
);
}
// A screen that allows users to take a picture using a given camera.
class TakePictureScreen extends StatefulWidget {
final CameraDescription camera;
const TakePictureScreen({
Key key,
@required this.camera,
}) : super(key: key);
@override
TakePictureScreenState createState() => TakePictureScreenState();
}
class TakePictureScreenState extends State<TakePictureScreen> {
CameraController _controller;
Future<void> _initializeControllerFuture;
@override
void initState() {
super.initState();
// To display the current output from the Camera,
// create a CameraController.
_controller = CameraController(
// Get a specific camera from the list of available cameras.
widget.camera,
// Define the resolution to use.
ResolutionPreset.medium,
);
// Next, initialize the controller. This returns a Future.
_initializeControllerFuture = _controller.initialize();
}
@override
void dispose() {
// Dispose of the controller when the widget is disposed.
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Take a picture')),
// Wait until the controller is initialized before displaying the
// camera preview. Use a FutureBuilder to display a loading spinner
// until the controller has finished initializing.
body:
FutureBuilder<void>(
future: _initializeControllerFuture,
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
// If the Future is complete, display the preview.
return CameraPreview(_controller);
} else {
// Otherwise, display a loading indicator.
return Center(child: CircularProgressIndicator());
}
},
),
floatingActionButton: FloatingActionButton(
child: Icon(Icons.camera_alt),
// Provide an onPressed callback.
onPressed: () async {
// Take the Picture in a try / catch block. If anything goes wrong,
// catch the error.
try {
// Ensure that the camera is initialized.
await _initializeControllerFuture;
// Construct the path where the image should be saved using the
// pattern package.
final path = join(
// Store the picture in the temp directory.
// Find the temp directory using the `path_provider` plugin.
(await getTemporaryDirectory()).path,
'${DateTime.now()}.png',
);
// Attempt to take a picture and log where it's been saved.
await _controller.takePicture(path);
// If the picture was taken, display it on a new screen.
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => DisplayPictureScreen(imagePath: path),
),
);
} catch (e) {
// If an error occurs, log the error to the console.
print(e);
}
},
),
);
}
}
// A widget that displays the picture taken by the user.
class DisplayPictureScreen extends StatelessWidget {
final String imagePath ;
const DisplayPictureScreen({Key key, this.imagePath}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Display the Picture')),
// The image is stored as a file on the device. Use the `Image.file`
// constructor with the given path to display the image.
body:
Image.file(File(imagePath)),
);
}
}

我不想显示预览屏幕，但偶尔会拍摄图像或视频。