docs: private void computeScales() {
  		int width = getWidth();
  		int height = getHeight();
  
  		width = (width-borderSize)/2;
  
  		// compute the scale factor for each image
  		scaleLeft = scaleRight = 1;
  		if( leftImage.getWidth() > width || leftImage.getHeight() > height ) {
  			double scaleX = (double)width/(double)leftImage.getWidth();
  			double scaleY = (double)height/(double)leftImage.getHeight();
  			scaleLeft = Math.min(scaleX,scaleY);
  		}
  		if( rightImage.getWidth() > width || rightImage.getHeight() > height ) {
  			double scaleX = (double)width/(double)rightImage.getWidth();
  			double scaleY = (double)height/(double)rightImage.getHeight();
  			scaleRight = Math.min(scaleX,scaleY);
  		}
  	}