/**
  * Retrieve the needed parameters for the renderer class.
  */
 public function getNeededParameters()
 {
     $this->requireParameter("renderer");
     $rendererName = $this->getParameter("renderer", "");
     $data = array();
     $factory = RendererFactoryRegistry::getInstance()->getRendererFactory($rendererName);
     return array("data" => $factory->getParameterObjectTypes());
 }