private function writeFont(XMLWriter $objWriter, Font $pFont)
    {
        // font
        $objWriter->startElement('font');
        //    Weird! The order of these elements actually makes a difference when opening Xlsx
        //        files in Excel2003 with the compatibility pack. It's not documented behaviour,
        //        and makes for a real WTF!

        // Bold. We explicitly write this element also when false (like MS Office Excel 2007 does
        // for conditional formatting). Otherwise it will apparently not be picked up in conditional
        // formatting style dialog
        if ($pFont->getBold() !== null) {
            $objWriter->startElement('b');
            $objWriter->writeAttribute('val', $pFont->getBold() ? '1' : '0');
            $objWriter->endElement();
        }

        // Italic
        if ($pFont->getItalic() !== null) {
            $objWriter->startElement('i');
            $objWriter->writeAttribute('val', $pFont->getItalic() ? '1' : '0');
            $objWriter->endElement();
        }

        // Strikethrough
        if ($pFont->getStrikethrough() !== null) {
            $objWriter->startElement('strike');
            $objWriter->writeAttribute('val', $pFont->getStrikethrough() ? '1' : '0');
            $objWriter->endElement();
        }

        // Underline
        if ($pFont->getUnderline() !== null) {
            $objWriter->startElement('u');
            $objWriter->writeAttribute('val', $pFont->getUnderline());
            $objWriter->endElement();
        }

        // Superscript / subscript
        if ($pFont->getSuperscript() === true || $pFont->getSubscript() === true) {
            $objWriter->startElement('vertAlign');
            if ($pFont->getSuperscript() === true) {
                $objWriter->writeAttribute('val', 'superscript');
            } elseif ($pFont->getSubscript() === true) {
                $objWriter->writeAttribute('val', 'subscript');
            }
            $objWriter->endElement();
        }

        // Size
        if ($pFont->getSize() !== null) {
            $objWriter->startElement('sz');
            $objWriter->writeAttribute('val', StringHelper::formatNumber($pFont->getSize()));
            $objWriter->endElement();
        }

        // Foreground color
        if ($pFont->getColor()->getARGB() !== null) {
            $objWriter->startElement('color');
            $objWriter->writeAttribute('rgb', $pFont->getColor()->getARGB());
            $objWriter->endElement();
        }

        // Name
        if ($pFont->getName() !== null) {
            $objWriter->startElement('name');
            $objWriter->writeAttribute('val', $pFont->getName());
            $objWriter->endElement();
        }

        $objWriter->endElement();
    }