/**
  * Accepts AJAX request containing list of IDs to be generated and returned.
  * Returns associative array mapping ID to thumbnail URL for all icons that were generated,
  * skipping any that could not be processed.
  */
 public static function generateIcons()
 {
     $ret = array();
     if (isset($_REQUEST['ids'])) {
         foreach ($_REQUEST['ids'] as $id) {
             // only return URL if different from default -- default image is already displayed on the client side
             $url = DG_Thumber::getInstance()->getThumbnail($id, 1, true, $is_default);
             if (!$is_default) {
                 $ret[$id] = $url;
             }
         }
     }
     wp_send_json($ret);
 }
 /**
  *
  * @param int $ID The attachment ID.
  * @param int $pg The page number to use (1-based numbering).
  * @param bool $generate_if_missing Whether to generate the thumbnail if it has not yet been generated.
  *
  * @return string The URL for the thumbnail NULL. Note that if generate_if_missing
  * is true then you will never get NULL -- you will get a default icon if generation fails.
  */
 public static function getThumbnail($ID, $pg = 1, $generate_if_missing = false)
 {
     include_once DG_PATH . 'inc/class-thumber.php';
     return DG_Thumber::getInstance()->getThumbnail($ID, $pg, $generate_if_missing);
 }