procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
  DataCol: Integer; Column: TColumn; State: TGridDrawState);
begin
  if Column.Index = 5 then
  with DBGrid1.Canvas do begin
    FillRect(Rect);
    TextOut(Rect.Left+2, Rect.Top+2, IntToStr(DBGrid1.DataSource.DataSet.RecNo));
  end;
end;哪位大哥知道帮忙解释一下