code: public synchronized Rect getFramingRect() {
      if (framingRect == null) {
        if (camera == null) {
          return null;
        }
        Point screenResolution = configManager.getScreenResolution();
        if (screenResolution == null) {
          // Called early, before init even finished
          return null;
        }
  
        int width = findDesiredDimensionInRange(screenResolution.x, MIN_FRAME_WIDTH, MAX_FRAME_WIDTH);
        int height = findDesiredDimensionInRange(screenResolution.y, MIN_FRAME_HEIGHT, MAX_FRAME_HEIGHT);
  
        int leftOffset = (screenResolution.x - width) / 2;
        int topOffset = (screenResolution.y - height) / 2;
        framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
        Log.d(TAG, "Calculated framing rect: " + framingRect);
      }
      return framingRect;
    }
docs: Calculates the framing rect which the UI should draw to show the user where to place the
  barcode. This target helps with alignment as well as forces the user to hold the device
  far enough away to ensure the image will be in focus.
  
  @return The rectangle to draw on screen in window coordinates.