/**
  * Perform a draw with the given renderer to the given canvas..
  *
  * @param drawingTools the given drawing tools.
  * @param renderer the given renderer.
  */
 public void draw(JoGLDrawingTools drawingTools, Renderer renderer) {
   if ((renderer != null) && (renderer instanceof JoGLRenderer)) {
     ((JoGLRenderer) renderer).draw(drawingTools);
   }
 }