如何在颤动中打开相机闪光灯？

Question

我正在构建一个应用程序，您的用户可以将他们的视频上传到 firebase。我正在为相机模块使用相机包。我想在用户单击闪光灯图标或将其关闭时打开闪光灯。

我试图找到一种通过相机包打开闪光灯的方法，但我找不到任何打开 flash.Then 的方法，我尝试使用 lamp 包，但是对于某些原因闪光灯打不开。

import 'dart:io';

import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/material.dart';
import 'package:camera/camera.dart';
import 'package:flutter_icons/flutter_icons.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:path/path.dart';
import 'package:path_provider/path_provider.dart';
import 'package:flutter/foundation.dart';
import 'package:lamp/lamp.dart';

enum FlashState { Flash_OFF, Flash_On, Flash_Auto }

class CameraView extends StatefulWidget {
  final List<CameraDescription> cameras = [];
  CameraView() {
    availableCameras().then((cams) {
      cameras.addAll(cams);
      print(cameras.length);
      print(cams.toString());
    });
  }

  @override
  _CameraViewState createState() => _CameraViewState();
}

class _CameraViewState extends State<CameraView>
    with SingleTickerProviderStateMixin {
  CameraController _controller;
  int _selectedCameraIndex;
  bool _isRecording;

  FlashState currentFlashState = FlashState.Flash_OFF;
  String flashIcon = 'flash-off';

  AnimationController _animationController;
  Animation _colorTween;

  @override
  void initState() {
    _animationController =
        AnimationController(vsync: this, duration: Duration(milliseconds: 300));
    _colorTween = ColorTween(begin: Colors.blueGrey, end: Colors.red)
        .animate(_animationController);
    // _controller = CameraController(widget.cameras[0], ResolutionPreset.high,
    //     enableAudio: true);
    // _isRecording = false;
    // _controller.initialize().then((_) {
    //   if (!mounted) {
    //     return;
    //   }
    //   setState(() {});
    // });
    if (widget.cameras.length > 0) {
      setState(() {
        _selectedCameraIndex = 0;
      });
      _switchCamera(widget.cameras[_selectedCameraIndex]);
    }
    super.initState();
  }

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

  Future<void> _startVideoRecording(BuildContext context) async {
    if (!_controller.value.isInitialized) {
      await showDialog(
          context: context,
          builder: (BuildContext context) {
            return AlertDialog(
              title: Text('Camera Not Responding.'),
              content: Center(
                child: Text('Something went wrong.Try Again Later.'),
              ),
              actions: <Widget>[
                FlatButton(
                  child: Text('Okay.'),
                  onPressed: () {
                    Navigator.of(context).pop();
                  },
                )
              ],
            );
          });
      return null;
    }
    if (_controller.value.isRecordingVideo) {
      return null;
    }
    setState(() {
      _isRecording = true;
    });
    final Directory appDirectory = await getApplicationDocumentsDirectory();
    final String videoDirectory = '${appDirectory.path}/Videos';
    await Directory(videoDirectory).create(recursive: true);
    final String currentTime = DateTime.now().millisecondsSinceEpoch.toString();
    final String filePath = '$videoDirectory/$currentTime.mp4';

    try {
      //Lamp.turnOn();
      await _controller.startVideoRecording(filePath);
      //Lamp.turnOff();
      StorageReference firebaseStorageReference =
          FirebaseStorage.instance.ref().child(basename(filePath));
      StorageUploadTask videoUploadTask = firebaseStorageReference.putFile(
        File(filePath),
        StorageMetadata(contentType: 'video/mp4'),
      );
      StorageTaskSnapshot uploadSnapshot = await videoUploadTask.onComplete;
    } catch (error) {
      print(error);
      return null;
    }
  }

  Future<void> _stopVideoRecording() async {
    if (!_controller.value.isRecordingVideo) {
      return null;
    }

    try {
      await _controller.stopVideoRecording();
      setState(() {
        _isRecording = false;
      });
    } catch (error) {
      print(error);
      return null;
    }
  }

  Future<void> _switchCamera(CameraDescription cameraDescription) async {
    if (_controller != null) {
      await _controller.dispose();
    }
    _controller = CameraController(cameraDescription, ResolutionPreset.high);

    _controller.addListener(() {
      if (mounted) {
        setState(() {});
      }
      if (_controller.value.hasError) {
        Fluttertoast.showToast(
            msg: 'An Error Occured',
            toastLength: Toast.LENGTH_SHORT,
            gravity: ToastGravity.BOTTOM,
            timeInSecForIos: 2,
            textColor: Colors.white,
            backgroundColor: Colors.black38);
      }
    });
    try {
      await _controller.initialize();
    } catch (error) {
      print(error);
    }

    if (mounted) {
      setState(() {});
    }
  }

  void _onSwitchCamera() {
    _selectedCameraIndex = _selectedCameraIndex < widget.cameras.length - 1
        ? _selectedCameraIndex + 1
        : 0;
    CameraDescription selectedCamera = widget.cameras[_selectedCameraIndex];
    _switchCamera(selectedCamera);
    setState(() {
      _selectedCameraIndex = _selectedCameraIndex;
    });
  }

  @override
  Widget build(BuildContext context) {
    return _controller.value.isInitialized
        ? Stack(
            fit: StackFit.expand,
            children: <Widget>[
              AspectRatio(
                aspectRatio: _controller.value.aspectRatio,
                child: CameraPreview(_controller),
              ),
              Positioned(
                left: MediaQuery.of(context).size.width * 0.40,
                bottom: MediaQuery.of(context).size.height * 0.04,
                child: AnimatedBuilder(
                  animation: _colorTween,
                  builder: (context, child) => IconButton(
                    icon: Icon(
                      MaterialCommunityIcons.getIconData('video'),
                    ),
                    color: _colorTween.value,
                    iconSize: 80.0,
                    onPressed: () {
                      if (!_isRecording) {
                        _animationController.forward();
                        _startVideoRecording(context);
                      } else if (_isRecording) {
                        _animationController.reverse();
                        _stopVideoRecording();
                      }
                    },
                  ),
                ),
              ),
              Positioned(
                right: 22.0,
                top: 22.0,
                child: IconButton(
                  icon: Icon(
                    MaterialCommunityIcons.getIconData('camera-switch'),
                  ),
                  onPressed: _onSwitchCamera,
                  iconSize: 28.0,
                ),
              ),
              Positioned(
                left: 22.0,
                top: 22.0,
                child: IconButton(
                  icon: Icon(
                    MaterialCommunityIcons.getIconData(flashIcon),
                  ),
                  onPressed: () {
                    currentFlashState =
                        currentFlashState.index < FlashState.values.length - 1
                            ? FlashState.values[currentFlashState.index + 1]
                            : FlashState.values[0];
                            if(currentFlashState == FlashState.Flash_On){
                              setState(() {
                                flashIcon = 'flash';
                              });
                              //Lamp.turnOn(); Turning on the flash through lamp package flutter but the flash not opening 
                            } else if(currentFlashState == FlashState.Flash_Auto){
                              setState(() {
                                flashIcon = 'flash-auto';
                              });
                            } else {
                              setState(() {
                                flashIcon = 'flash-off';
                              });
                              //Lamp.turnOff(); 
                            }
                  },
                ),
              )
            ],
          )
        : Container(
            child: Center(
              child: Text('Loading'),
            ),
          );
  }
}

Answer 1

目前还没有支持使用闪光灯的相机插件。人们使用的一种解决方法是使用此包 https://pub.dev/packages/lamp 在拍照前打开 phone lamp，然后关闭。

这不是理想的解决方案，但目前是可用的最佳解决方案

Answer 2

根据最近相机更新：^0.8.0。您可以手动使用相机闪光灯：

第一步：首先按照整个相机说明进行操作： https://flutter.dev/docs/cookbook/plugins/picture-using-camera

第二步：然后创建任何按钮，并在其 onPressed 功能上，只写这一行。

//**For Flash OFF**:

 ElevatedButton(
            onPressed: () {
              _cameraController.setFlashMode(FlashMode.off);
            },
            style: ElevatedButton.styleFrom(primary: Colors.transparent),
            child: Text(
              "Flash Off",
              style: TextStyle(
                  color: Colors.white, backgroundColor: Colors.transparent),
            ),
          ),


 // **For Flash ON**
     ElevatedButton(
            onPressed: () {
              _cameraController.setFlashMode(FlashMode.always);
            },
            style: ElevatedButton.styleFrom(primary: Colors.transparent),
            child: Text(
              "Flash On",
              style: TextStyle(
                  color: Colors.white, backgroundColor: Colors.transparent),
            ),
          )
 //**For AUTO Flash:**
  ElevatedButton(
            onPressed: () {
              _cameraController.setFlashMode(FlashMode.auto);
            },
            style: ElevatedButton.styleFrom(primary: Colors.transparent),
            child: Text(
              "Auto Flash",
              style: TextStyle(
                  color: Colors.white, backgroundColor: Colors.transparent),
            ),
          )

Answer 3

Asim Zubairs 的回答是正确的，对于 flutter camera 插件，最好强调 FlashMode.always 仅在拍摄照片时打开手电筒，但如果您想打开手电筒并保留它，因为像视频录制这样的情况，FlashMode.torch 可以解决。

这是来自相机插件的 FlashMode 枚举

enum FlashMode {
  /// Do not use the flash when taking a picture.
  off,

  /// Let the device decide whether to flash the camera when taking a picture.
  auto,

  /// Always use the flash when taking a picture.
  always,

  /// Turns on the flash light and keeps it on until switched off.
  torch,
}

如何在颤动中打开相机闪光灯？

How to turn on camera flash in flutter?

android-camera

dart

flutter