/**
  * Render slideshow preview
  */
 public static function renderSlideshowPreview()
 {
     global $wgRequest;
     wfProfileIn(__METHOD__);
     // decode JSON-encoded slideshow data
     $gallery = json_decode($wgRequest->getVal('gallery'), true);
     if (empty($gallery['params']['rssfeed'])) {
         $html = WikiaPhotoGalleryHelper::renderSlideshowPreview($gallery);
     } else {
         $html = WikiaPhotoGalleryHelper::renderFeedSlideshowPreview($gallery);
     }
     wfProfileOut(__METHOD__);
     return array('html' => $html);
 }