SetupCameraParameter.kt

    /**
     * Sets up member variables related to front camera.
     * @param width  The width of available size for camera preview
     * @param height The height of available size for camera preview
     */
    private fun setUpCameraOutputsFront(width: Int, height: Int) {
        val manager = activity?.getSystemService(Context.CAMERA_SERVICE) as CameraManager
        try {
            for (cameraId in manager.cameraIdList) {
                val characteristics = manager.getCameraCharacteristics(cameraId)

                // We need front facing camera.
                val cameraDirection = characteristics.get(CameraCharacteristics.LENS_FACING)
                if (cameraDirection != null &&
                    cameraDirection == CameraCharacteristics.LENS_FACING_BACK) {
                    continue
                }
                val map = characteristics.get(
                    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP) ?: continue

                // For still image captures, we use the largest available size.
                val aspectRatio = Collections.max(Arrays.asList(*map.getOutputSizes(ImageFormat.JPEG)), CompareSizesByViewAspectRatio(textureViewFront.height, textureViewFront.width))
                
                imageReaderFront = ImageReader.newInstance(aspectRatio.width, aspectRatio.height, ImageFormat.JPEG, /*maxImages*/ 2).apply {
                    setOnImageAvailableListener(onImageAvailableListenerFront, backgroundHandler)
                }
                // Find out if we need to swap dimension to get the preview size relative to sensor
                // coordinate.
                val displayRotation = activity!!.windowManager.defaultDisplay.rotation

                sensorOrientationFront = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION)!!
                val swappedDimensions = areDimensionsSwappedFront(displayRotation)

                val displaySize = Point()
                activity!!.windowManager.defaultDisplay.getSize(displaySize)
                val rotatedPreviewWidth = if (swappedDimensions) height else width
                val rotatedPreviewHeight = if (swappedDimensions) width else height
                var maxPreviewWidth = if (swappedDimensions) displaySize.y else displaySize.x
                var maxPreviewHeight = if (swappedDimensions) displaySize.x else displaySize.y

                if (maxPreviewWidth > MAX_PREVIEW_WIDTH) maxPreviewWidth = MAX_PREVIEW_WIDTH
                if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) maxPreviewHeight = MAX_PREVIEW_HEIGHT

                previewSizeFront = chooseOptimalSize(map.getOutputSizes(SurfaceTexture::class.java),
                    rotatedPreviewWidth, rotatedPreviewHeight,
                    maxPreviewWidth, maxPreviewHeight,
                    aspectRatio)

                this.cameraIdFront = cameraId
                // We've found a viable camera and finished setting up member variables,
                // so we don't need to iterate through other available cameras.
                return
            }
        } catch (e: CameraAccessException) {
            Log.e(TAG, e.toString())
        } catch (e: NullPointerException) {
            // Currently an NPE is thrown when the Camera2API is used but not supported on the
            // device this code runs.
            ErrorDialog.newInstance(getString(R.string.camera_error))
                .show(childFragmentManager, FRAGMENT_DIALOG)
        }
    }