private function setShadowDistance($distance)
    {
        if ($distance !== null) {
            $this->shadowProperties['distance'] = (string) $this->getExcelPointsWidth($distance);
        }

        return $this;
    }
private function setShadowDistance($distance)
    {
        if ($distance !== null) {
            $this->shadowProperties['distance'] = (string) $this->getExcelPointsWidth($distance);
        }

        return $this;
    }
private function setShadowDistance ( $ distance ) { if ( $ distance !== null ) { $ this -> shadowProperties [ 'distance' ] = ( string ) $ this -> getExcelPointsWidth ( $ distance ) ; } return $ this ; }
Set Shadow Distance

@param float $distance

@return PHPExcel_Chart_Axis
Set Shadow Distance