PiwikTracker::getUserIdHashed PHP Method

    public static function getUserIdHashed($id)
    {
        return substr(sha1($id), 0, 16);
    }

 /**
  * Converts a User ID string to the Visitor ID Binary representation.
  *
  * @param $userId
  * @return string
  */
 public static function convertUserIdToVisitorIdBin($userId)
 {
     require_once PIWIK_INCLUDE_PATH . '/libs/PiwikTracker/PiwikTracker.php';
     $userIdHashed = \PiwikTracker::getUserIdHashed($userId);
     return self::convertVisitorIdToBin($userIdHashed);
 }