PhpOffice\PhpPresentation\Writer\ODPresentation\Styles::writeBackgroundStyle PHP Method

    protected function writeBackgroundStyle(XMLWriter $objWriter, Image $oBkgImage, $numSlide)
    {
        $objWriter->startElement('draw:fill-image');
        $objWriter->writeAttribute('draw:name', 'background_' . $numSlide);
        $objWriter->writeAttribute('xlink:href', 'Pictures/' . str_replace(' ', '_', $oBkgImage->getIndexedFilename($numSlide)));
        $objWriter->writeAttribute('xlink:type', 'simple');
        $objWriter->writeAttribute('xlink:show', 'embed');
        $objWriter->writeAttribute('xlink:actuate', 'onLoad');
        $objWriter->endElement();
    }