Flutter Camera Plugin 拍摄暗图像错误

Posted 2023-02-23

【中文标题】Flutter Camera Plugin 拍摄暗图像错误

【英文标题】：Flutter Camera Plugin taking dark image bug

【发布时间】：2020-04-10 22:02:21

【问题描述】：

我从颤振的相机插件中得到暗图像。

相机预览显示正确，但拍照后变得太暗。

我搜索了一下，发现是关于 FPS 和相机的曝光。

我该如何解决这个问题？

我需要在我的应用中显示相机预览并拍照。

请不要告诉我使用 image_picker 包。

设备：红米note 4

安卓操作系统：7.0

这是图片

dark image

这里是代码

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';

Future<void> main() async 
  // 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;

  runApp(
    MaterialApp(
      theme: ThemeData.dark(),
      home: TakePictureScreen(
        // Pass the appropriate camera to the TakePictureScreen widget.
        camera: firstCamera,
      ),
    ),
  );


// 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)),
    );
  

【问题讨论】：

我很乐意为您提供帮助，但我已经尝试了您的代码，并且在我的 OnePlus 6T（使用 android 10）上，照片效果很好，不像您分享的示例那样暗。我无法重现您的问题。你还用过什么其他的相机包，都是一样的问题吗？

你看过我的评论吗？您悬赏了这个问题，但甚至没有回复您收到的一条评论。

我认为是相机问题，如果不尝试使用 image_picker 包https://pub.dev/packages/image_picker

@OmarSherif 仔细阅读帖子...我说不要告诉我使用 image_picker 包。我的相机没有任何问题...

我在 Pixel 3 上尝试过，照片也像 Joao 提到的那样很好。但是，这可能特定于某些设备，github.com/flutter/flutter/issues/19038 和github.com/flutter/flutter/issues/26079 你也可以在那里发布你的问题吗？谢谢！

【参考方案1】：

我认为这与延迟无关，如果不处理曝光，图像就会变暗。 此外曝光需要焦点预捕获才能工作，现在官方插件中没有处理。

你可以使用这个插件：CamerAwesome

官方插件已经被彻底抛弃了。这个插件包括闪光灯、变焦、自动对焦、曝光......并且不需要初始化。 它使用值通知器直接在预览中更改数据，如下所示：

  // init Notifiers
  ValueNotifier<CameraFlashes> _switchFlash = ValueNotifier(CameraFlashes.NONE);
  ValueNotifier<Sensors> _sensor = ValueNotifier(Sensors.BACK);
  ValueNotifier<Size> _photoSize = ValueNotifier(null);

  @override
  Widget build(BuildContext context) 
    return CameraAwesome(
      onPermissionsResult: (bool result)  
      selectDefaultSize: (List<Size> availableSizes) => Size(1920, 1080),
      onCameraStarted: ()  ,
      onOrientationChanged: (CameraOrientations newOrientation)  ,
      zoom: 0.64,
      sensor: _sensor,
      photoSize: _photoSize,
      switchFlashMode: _switchFlash,
      orientation: DeviceOrientation.portraitUp,
      fitted: true,
    );
  ;

【讨论】：

获得 CameraAwesome 包的相同输出，对我没用。谢谢

【参考方案2】：

拍照前延迟一下。

Future.delayed(const Duration(milliseconds: 500), () 
_controller.takePicture(path);
);

【讨论】：

你测试过这个吗？