/**
  * Gets an array containing the file formats that are supported by the renderer.
  * 
  * @return array An array containing the supported file formats.
  */
 public function getSupportedFileFormats()
 {
     // build formats only once
     if (self::$supported_formats == null) {
         self::$supported_formats = explode(",", self::SUPPORTED_FORMATS);
     }
     return self::$supported_formats;
 }
 /**
  * Loads the available preview renderers. That is built in renderers and plugins.
  * 
  * @return array The available renderers.
  */
 private static function loadAvailableRenderers()
 {
     // already loaded?
     if (self::$renderers != null) {
         return;
     }
     $r = array();
     // get registered and active plugins
     global $ilPluginAdmin;
     $pl_names = $ilPluginAdmin->getActivePluginsForSlot(IL_COMP_SERVICE, "Preview", "pvre");
     foreach ($pl_names as $pl) {
         $plugin = ilPluginAdmin::getPluginObject(IL_COMP_SERVICE, "Preview", "pvre", $pl);
         $r[] = $plugin->getRendererClassInstance();
     }
     // add default renderers
     include_once "./Services/Preview/classes/class.ilImageMagickRenderer.php";
     $r[] = new ilImageMagickRenderer();
     include_once "./Services/Preview/classes/class.ilGhostscriptRenderer.php";
     if (ilGhostscriptRenderer::isGhostscriptInstalled()) {
         $r[] = new ilGhostscriptRenderer();
     }
     self::$renderers = $r;
 }