如何获取前置摄像头的预览图像

let cameraManager = await camera.getCameraManager(context); 
let camerasInfo = await cameraManager.getSupportedCameras(); 
let cameraDevice = this.camerasInfo[0];

let cameraInput = await cameraManager.createCameraInput(cameraDevice); 
await this.cameraInput.open();

let outputCapability = await this.cameraManager.getSupportedOutputCapability(cameraDevice); 
let previewProfile = this.outputCapability.previewProfiles[0]; 
let previewOutput = await cameraManager.createPreviewOutput(previewProfile, previewId);

let captureSession = await cameraManager.createCaptureSession(); 
await captureSession.beginConfig(); 
await captureSession.addInput(cameraInput); 
await captureSession.addOutput(previewOutput); 
await this.captureSession.commitConfig() 
await this.captureSession.start();