/**
* Write Dimension
*
* @param PHPExcel_Shared_XMLWriter $objWriter XML Writer
* @param PHPExcel_Worksheet $pSheet Worksheet
* @throws Exception
*/
private function _writeDimension(PHPExcel_Shared_XMLWriter $objWriter = null, PHPExcel_Worksheet $pSheet = null)
{
// dimension
$objWriter->startElement('dimension');
$objWriter->writeAttribute('ref', $pSheet->calculateWorksheetDimension());
$objWriter->endElement();
}