private function writePatternFill(PHPExcel_Shared_XMLWriter $objWriter = null, PHPExcel_Style_Fill $pFill = null)
    {
        // fill
        $objWriter->startElement('fill');

        // patternFill
        $objWriter->startElement('patternFill');
        $objWriter->writeAttribute('patternType', $pFill->getFillType());

        if ($pFill->getFillType() !== PHPExcel_Style_Fill::FILL_NONE) {
            // fgColor
            if ($pFill->getStartColor()->getARGB()) {
                $objWriter->startElement('fgColor');
                $objWriter->writeAttribute('rgb', $pFill->getStartColor()->getARGB());
                $objWriter->endElement();
            }
        }
        if ($pFill->getFillType() !== PHPExcel_Style_Fill::FILL_NONE) {
            // bgColor
            if ($pFill->getEndColor()->getARGB()) {
                $objWriter->startElement('bgColor');
                $objWriter->writeAttribute('rgb', $pFill->getEndColor()->getARGB());
                $objWriter->endElement();
            }
        }

        $objWriter->endElement();

        $objWriter->endElement();
    }