dbgrid 使用小结

1、插入其他可视组件(注意：自动生成列和手动生成时的用法有所不同，手动时用DBGrid1DrawDataCell没有反应)

DrawDataCell事件是绘制单元格，当获得焦点网格所对应的字段与组合框所对应的字段一致时，移动组合框到获得焦点的网格上，并且使组合框可视，从而达到在DBGrid指定列上显示DBComboBox的功能。设置DBGrid1的OnDrawDataCell事件如下：

procedure TForm1.DBGrid1DrawColumnCell
(Sender: TObject; const Rect: TRect;
Column: TColumn; State: TGridDrawState);
begin
if (gdFocused in State) then
begin
if (Column.FieldName = DBComboBox1.DataField ) then
begin
DBComboBox1.Left := Rect.Left + DBGrid1.Left;
DBComboBox1.Top := Rect.Top + DBGrid1.top;
DBComboBox1.Width := Rect.Right - Rect.Left;
DBComboBox1.Height := Rect.Bottom - Rect.Top;
DBComboBox1.Visible := True;
end;
end;
end;

DBGrid指定单元格未获得焦点时不显示DBComboBox，设置DBGrid1的OnColExit事件如下： 
procedure TForm1.DBGrid1ColExit(Sender: TObject);
begin
If DBGrid1.SelectedField.FieldName 
= DBComboBox1.DataField then
begin
DBComboBox1.Visible := false;
end;
end;
当DBGrid指定列获得焦点时DrawDataCell事件只是绘制单元格，并显示DBComboBox，但是DBComboBox并没有获得焦点，数据的输入还是在单元格上进行。在DBGrid1的KeyPress事件中调用SendMessage这个 Windows API函数将数据输入传输到DBComboBox上，从而达到在DBComboBox上进行数据输入。因此还要设置KeyPress事件如下：

procedure TForm1.DBGrid1KeyPress
(Sender: TObject; var Key: Char);
begin
if (key < > chr(9)) then
begin
if (DBGrid1.SelectedField.FieldName
=DBComboBox1.DataField) then
begin
DBComboBox1.SetFocus;
SendMessage(DBComboBox1.Handle, 
WM_Char, word(Key), 0);
end;
end;
end;
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2、针对某个条件改变颜色(和1有一样的问题)

procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
DataCol: Integer; Column: TColumn; State: TGridDrawState);
begin
if (Column.FieldName='Area') then begin
dbgrid1.Canvas.Brush.Color:=clred;
(Sender as TDBGrid).Canvas.FillRect(Rect);
(Sender as TDBGrid).Canvas.TextRect(Rect, Rect.Left + 2, Rect.Top + 2,table1Area.asstring);
end;
end;

3.在最后一行按向下键头时不让增加数据：
先定义一个伪子类：
type
TMydbgrid=class(TDbgrid)
end;

procedure TkaoqinForm.DBGrid1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if key=40 then
if TMydbgrid(dbgrid1).Row>=TMydbgrid(dbgrid1).RowCount-1 then abort;
//if dm.ry3.recno=dm.ry3.RecordCount then abort;
end;

4。回车键移动光标：

procedure TTimeTableForm.wwDBGrid1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if Key=13 then
with TwwDBGrid(Sender) do
if selectedindex < (fieldcount - 1) then
selectedindex := selectedindex + 1
else selectedindex := 0;

end;

5.控制每一行的颜色。
procedure TkaoqinForm.DBGrid1DrawDataCell(Sender: TObject;
const Rect: TRect; Field: TField; State: TGridDrawState);
begin
if (dbgrid1.DataSource.DataSet.RecNo mod 2)=0 then
begin
dbgrid1.Canvas.Font.Color:=clblue;
dbgrid1.Canvas.Brush.Color:=clMoneyGreen;
end;
dbgrid1.DefaultDrawDataCell(rect,field,state);
end;