我正在关注这个GoogleCodelababoutCameraX当我开始添加相机预览时，我会这样做:valpreviewConfig=PreviewConfig.Builder().apply{setTargetAspectRatio(Rational(1,1))setTargetResolution(Size(640,640))setLensFacing(CameraX.LensFacing.BACK)}.build()valpreview=Preview(previewConfig)preview.setOnPreviewOutputUpdateListener{previewOu