camera 获取预览数据

创建了预览数据 output 
this.mAnalysisImageReceiver = image.createImageReceiver(size.width, size.height, image.ImageFormat.JPEG, 4) 
this.mAnalysisImageReceiver.on(‘imageArrival’, async () => { 
  let latestImage: image.Image | null = null 
  try { 
    if (this.mAnalysisImageReceiver) { 
      latestImage = await this.mAnalysisImageReceiver.readLatestImage() 
      if (latestImage) { 
        let data = await latestImage.getComponent(image.ComponentType.JPEG) 
        await latestImage.release() 
        this.mCallback?.onImageAnalysis(data) 
      } 
    } 
  } catch (e) { 
    CameraLog.e(TAG, ‘prepareImageCaptureReader’, e) 
  } finally { 
    latestImage?.release() 
  } 
}) 
let previewSurfaceId: string = await this.mAnalysisImageReceiver.getReceivingSurfaceId() 
CameraLog.d(TAG, prepareImageAnalysisReader: size = ${size} id = ${previewSurfaceId}) 
this.mAnalysisOutput = this.getCameraManager().createPreviewOutput({ 
  format: camera.CameraFormat.CAMERA_FORMAT_JPEG, 
  size: size 
}, previewSurfaceId) 
 
添加进 session 中 
if (this.mAnalysisOutput) { 
  captureSession.addOutput(this.mAnalysisOutput) 
}