Pimcore\Model\Asset\Image\Thumbnail\Config::getByAutoDetect PHP Method

    public static function getByAutoDetect($config)
    {
        $thumbnail = null;
        if (is_string($config)) {
            try {
                $thumbnail = self::getByName($config);
            } catch (\Exception $e) {
                Logger::error("requested thumbnail " . $config . " is not defined");
                return false;
            }
        } elseif (is_array($config)) {
            // check if it is a legacy config or a new one
            if (array_key_exists("items", $config)) {
                $thumbnail = self::getByArrayConfig($config);
            } else {
                $thumbnail = self::getByLegacyConfig($config);
            }
        } elseif ($config instanceof self) {
            $thumbnail = $config;
        }
        return $thumbnail;
    }

 /**
  * @param $thumbnailName
  * @param int $page
  * @param bool $deferred $deferred deferred means that the image will be generated on-the-fly (details see below)
  * @return mixed|string
  */
 public function getImageThumbnail($thumbnailName, $page = 1, $deferred = false)
 {
     // just 4 testing
     //$this->clearThumbnails(true);
     if (!\Pimcore\Document::isAvailable()) {
         \Logger::error("Couldn't create image-thumbnail of document " . $this->getFullPath() . " no document adapter is available");
         return "/pimcore/static/img/filetype-not-supported.png";
     }
     $thumbnail = Image\Thumbnail\Config::getByAutoDetect($thumbnailName);
     $thumbnail->setName("document_" . $thumbnail->getName() . "-" . $page);
     try {
         if (!$deferred) {
             $converter = \Pimcore\Document::getInstance();
             $converter->load($this->getFileSystemPath());
             $path = PIMCORE_TEMPORARY_DIRECTORY . "/document-image-cache/document_" . $this->getId() . "__thumbnail_" . $page . ".png";
             if (!is_dir(dirname($path))) {
                 \Pimcore\File::mkdir(dirname($path));
             }
             $lockKey = "document-thumbnail-" . $this->getId() . "-" . $page;
             if (!is_file($path) && !Model\Tool\Lock::isLocked($lockKey)) {
                 Model\Tool\Lock::lock($lockKey);
                 $converter->saveImage($path, $page);
                 Model\Tool\Lock::release($lockKey);
             } else {
                 if (Model\Tool\Lock::isLocked($lockKey)) {
                     return "/pimcore/static/img/please-wait.png";
                 }
             }
         }
         if ($thumbnail) {
             $path = Image\Thumbnail\Processor::process($this, $thumbnail, $path, $deferred);
         }
         return preg_replace("@^" . preg_quote(PIMCORE_DOCUMENT_ROOT) . "@", "", $path);
     } catch (\Exception $e) {
         \Logger::error("Couldn't create image-thumbnail of document " . $this->getFullPath());
         \Logger::error($e);
     }
     return "/pimcore/static/img/filetype-not-supported.png";
 }