private function drawCellBackground($row_number, $cell_number)
    {
        if ($this->size%2) {
            return $this->background && (($row_number%2 && $cell_number%2) || (!($row_number%2) && !($cell_number%2)));
        }

        return $this->background && (($row_number%2 && !($cell_number%2)) || (!($row_number%2) && $cell_number%2));
    }