public function cloneFontFrom(&$pdf)
    {
        $this->n                = &$pdf->getN();
        $this->fonts            = &$pdf->getFonts();
        $this->FontFiles        = &$pdf->getFontFiles();
        $this->diffs            = &$pdf->getDiffs();
        $this->fontlist         = &$pdf->getFontList();
        $this->numfonts         = &$pdf->getNumFonts();
        $this->fontkeys         = &$pdf->getFontKeys();
        $this->font_obj_ids     = &$pdf->getFontObjIds();
        $this->annotation_fonts = &$pdf->getAnnotFonts();
    }