private function writeLayout(XMLWriter $objWriter, Layout $layout = null)
    {
        $objWriter->startElement('c:layout');

        if ($layout !== null) {
            $objWriter->startElement('c:manualLayout');

            $layoutTarget = $layout->getLayoutTarget();
            if ($layoutTarget !== null) {
                $objWriter->startElement('c:layoutTarget');
                $objWriter->writeAttribute('val', $layoutTarget);
                $objWriter->endElement();
            }

            $xMode = $layout->getXMode();
            if ($xMode !== null) {
                $objWriter->startElement('c:xMode');
                $objWriter->writeAttribute('val', $xMode);
                $objWriter->endElement();
            }

            $yMode = $layout->getYMode();
            if ($yMode !== null) {
                $objWriter->startElement('c:yMode');
                $objWriter->writeAttribute('val', $yMode);
                $objWriter->endElement();
            }

            $x = $layout->getXPosition();
            if ($x !== null) {
                $objWriter->startElement('c:x');
                $objWriter->writeAttribute('val', $x);
                $objWriter->endElement();
            }

            $y = $layout->getYPosition();
            if ($y !== null) {
                $objWriter->startElement('c:y');
                $objWriter->writeAttribute('val', $y);
                $objWriter->endElement();
            }

            $w = $layout->getWidth();
            if ($w !== null) {
                $objWriter->startElement('c:w');
                $objWriter->writeAttribute('val', $w);
                $objWriter->endElement();
            }

            $h = $layout->getHeight();
            if ($h !== null) {
                $objWriter->startElement('c:h');
                $objWriter->writeAttribute('val', $h);
                $objWriter->endElement();
            }

            $objWriter->endElement();
        }

        $objWriter->endElement();
    }