关于dbgrid的重画(10分)

procedure TfrmcasehistoryUpd.dbgrid1DrawColumnCell(Sender: TObject;
const Rect: TRect; DataCol: Integer; Column: TColumn;
State: TGridDrawState);
begin
if (column.Index=8)and (column.Grid.Fields[8].asstring<>'') then
begin
case column.Grid.Fields[8].asinteger of
0: begin
dbgrid1.Canvas.Font.Color:=clred;
dbgrid1.Canvas.TextOut(rect.left+2,rect.top+2,'初诊挂号');
end;
1: begin
dbgrid1.Canvas.Font.Color:=$009AEB94;
dbgrid1.Canvas.TextOut(rect.left+2,rect.top+2,'预 约');
end;
3: begin
dbgrid1.Canvas.Font.Color:=$00FAAD50;
dbgrid1.Canvas.TextOut(rect.left+2,rect.top+2,'就诊完毕');
end;
end;

end;
为什么不会重画
我已经把 defaultdrawing:=true
另外 defaultdrawcolumncell(rect,datacol,column,state)中的值怎么
给column赋值