public static function get_comments($gradeid, $pageno, $draft) {
        global $DB;

        $comments = array();
        $params = array('gradeid'=>$gradeid, 'pageno'=>$pageno, 'draft'=>1);
        if (!$draft) {
            $params['draft'] = 0;
        }
        // Fetch comments ordered by position on the page.
        $records = $DB->get_records('assignfeedback_editpdf_cmnt', $params, 'y, x');
        foreach ($records as $record) {
            array_push($comments, new comment($record));
        }

        return $comments;
    }