Classes/Service/PluginConfigurationService.php
protected function getPageId($pid)
    {
        $pid = (int)$pid;
        if ($pid > 0) {
            return $pid;
        }
        $row = BackendUtilityCore::getRecord('tt_content', abs($pid), 'uid,pid');
        return $row['pid'];
    }
protected function getPageId($pid)
    {
        $pid = (int)$pid;
        if ($pid > 0) {
            return $pid;
        }
        $row = BackendUtilityCore::getRecord('tt_content', abs($pid), 'uid,pid');
        return $row['pid'];
    }
protected function getPageId ( $ pid ) { $ pid = ( int ) $ pid ; if ( $ pid > 0 ) { return $ pid ; } $ row = BackendUtilityCore :: getRecord ( 'tt_content' , abs ( $ pid ) , 'uid,pid' ) ; return $ row [ 'pid' ] ; }
Get page id, if negative, then it is a "after record"

@param int $pid
@return int
Get page id if negative then it is a after record