* $spreadsheet->getActiveSheet()->getStyle('B2')->getFill()->applyFromArray( * [ * 'fillType' => Fill::FILL_GRADIENT_LINEAR, * 'rotation' => 0.0, * 'startColor' => [ * 'rgb' => '000000' * ], * 'endColor' => [ * 'argb' => 'FFFFFFFF' * ] * ] * ); *