在HarmonyOS开发中 相机打开闪光灯设置无效 ？

Question

前置条件是满足的设备支持闪光灯，这是设置闪光灯的代码：
let flashMode = this.isOpenFlash ? camera.FlashMode.FLASH_MODE_OPEN : camera.FlashMode.FLASH_MODE_CLOSE this.videoSession.setFlashMode(flashMode)
没有报错，但是闪光灯也没有打开。

Answer 1

相机打开闪光灯可以参考以下步骤：
1、在module.json5添加权限。

ohos.permission.MICROPHONE
ohos.permission.CAMERA
ohos.permission.MEDIA_LOCATION
ohos.permission.WRITE_MEDIA

2、动态授权：

aboutToAppear() { 
  let context = getContext() as common.UIAbilityContext; 
  abilityAccessCtrl.createAtManager().requestPermissionsFromUser(context, [ 
    'ohos.permission.MICROPHONE', 
    'ohos.permission.CAMERA', 
    'ohos.permission.MEDIA_LOCATION', 
    'ohos.permission.WRITE_MEDIA']).then(()=>{ 
  }); 
  console.info(`surfaceId=${this.surfaceId}`); 
}

3、builder函数：

build() { 
  Column() { 
    // 创建XComponent 
    XComponent({ 
      id: '', 
      type: 'surface', 
      libraryname: '', 
      controller: this.mXComponentController 
    }) 
      .onLoad(() => { 
        // 设置Surface宽高（1920*1080），预览尺寸设置参考前面 previewProfilesArray 获取的当前设备所支持的预览分辨率大小去设置 
        this.mXComponentController.setXComponentSurfaceSize({surfaceWidth:1920,surfaceHeight:1080}); 
        // 获取Surface ID 
        this.surfaceId = this.mXComponentController.getXComponentSurfaceId(); 
        this.createDualChannelPreview(this.surfaceId); 
      }) 
      .width('1920px') 
      .height('1080px') 
    Button('打开闪光灯').width(50).height(50).onClick(()=>{ 
      this.setFlash(camera.FlashMode.FLASH_MODE_ALWAYS_OPEN) 
    }) 
    Button('关闭闪光灯').width(50).height(50).onClick(()=>{ 
      this.setFlash(camera.FlashMode.FLASH_MODE_CLOSE) 
    }) 
  } 
}

4、创建相机会话：

async createDualChannelPreview(XComponentSurfaceId: string): Promise<void> { 
  let cameraManager = camera.getCameraManager(this.context); 
  let camerasDevices: Array<camera.CameraDevice> = cameraManager.getSupportedCameras(); 
  let profiles: camera.CameraOutputCapability = cameraManager.getSupportedOutputCapability(camerasDevices[0]); // 获取对应相机设备profiles 
  let previewProfiles: Array<camera.Profile> = profiles.previewProfiles; 
  let previewProfilesObj: camera.Profile = previewProfiles[0]; 
  let previewOutput: camera.PreviewOutput = cameraManager.createPreviewOutput(previewProfilesObj, XComponentSurfaceId); 
  let cameraInput: camera.CameraInput = cameraManager.createCameraInput(camerasDevices[0]); 
  await cameraInput.open(); 
  this.captureSession = cameraManager.createCaptureSession(); 
  this.captureSession?.beginConfig(); 
  this.captureSession?.addInput(cameraInput); 
  this.captureSession?.addOutput(previewOutput); 
  await this.captureSession?.commitConfig(); 
  await this.captureSession?.start(); 
}

5、开启闪光灯：

setFlash(flashMode: camera.FlashMode) { 
  if (this.captureSession != null) { 
    let focusModeStatus: boolean = this.captureSession?.isFlashModeSupported(flashMode); 
    if (focusModeStatus) { 
      this.captureSession?.setFlashMode(flashMode); 
    } 
  } 
}