public function cleanUp() {
        unset($this->pdfdata);
        $this->pdfdata = '';
        unset($this->objstreams);
        $this->objstreams = array();
        unset($this->objects);
        $this->objects = array();
        unset($this->objstreamobjs);
        $this->objstreamobjs = array();
        unset($this->xref);
        $this->xref = array();
        unset($this->objoffsets);
        $this->objoffsets = array();
        unset($this->pages);
        $this->pages = array();
    }