public function getLayoutWidth()
    {
        $paperWidth     = $this->_paperWidth !== null   ? $this->_paperWidth    : $this->_rtf->getPaperWidth();
        $marginLeft     = $this->_marginLeft !== null   ? $this->_marginLeft    : $this->_rtf->getMarginLeft();
        $marginRight    = $this->_marginRight !== null  ? $this->_marginRight   : $this->_rtf->getMarginRight();
        $layoutWidth    = $paperWidth - $marginLeft - $marginRight;

        if ($layoutWidth <= 0) {
            throw new PHPRtfLite_Exception('The paper layout width is lower or equal zero!');
        }

        return $layoutWidth;
    }