[Lazarus] Problems drag&dropping from a TStringGrid

[Luca Olivetti]

En/na Luca Olivetti ha escrit:
> I'm porting some delphi code. In one of my forms I drag from a 
> TStringGrid and drop to a TSpinEdit (to "visually" put the value in one 
> of the rows of the string-grid in one of multiple spin edits).
> The first problem is that TSpinEdit doesn't expose OnDragDrop and 
> OnDragOver (I just made a derived component to publish those 
> properties), but the real problem is that while I drag the selected row 
> in the stringgrid changes. Is there any way to avoid that?

I finally did it this way: move the BeginDrag in MouseMove instead of 
MouseDowm, track the button in MouseDown, disallow cell selection while 
dragging in SelectCell.

procedure TAjustesSortens.TelegramaFisExit(Sender: TObject);
begin
   FSelectedRow:=0;
end;

procedure TAjustesSortens.TelegramaFisMouseDown(Sender: TObject;
   Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
   FSelectedRow:=0;
   if Button=mbLeft then FClicked:=true;
end;

procedure TAjustesSortens.TelegramaFisMouseMove(Sender: TObject;
   Shift: TShiftState; X, Y: Integer);
begin
   if FClicked then
   begin
      with Sender as TStringGrid do
      begin
        if (Row>0) then
        begin
          FSelectedRow:=Row;
          BeginDrag(false);
        end;
      end
   end;
end;

procedure TAjustesSortens.TelegramaFisMouseUp(Sender: TObject;
   Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
   FClicked:=false;
end;

procedure TAjustesSortens.TelegramaFisSelectCell(Sender: TObject; aCol,
   aRow: Integer; var CanSelect: Boolean);
begin
   if FSelectedRow>0 then CanSelect:=false;
end;


> 
> This is what I have in my code:
> 
> //The Mouse Down event handler of the TStringGrid
> procedure TAjustesSortens.TelegramaFisMouseDown(Sender: TObject;
>    Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
> begin
>    if Button=mbLeft then
>    begin
>       with Sender as TStringGrid do
>       begin
>         if (Row>0) then BeginDrag(false);
>       end
>    end;
> 
> end;
> 
> //Drag over event handler shared by all SpinEdits
> procedure TAjustesSortens.sortenDragOver(Sender, Source: TObject; X,
>    Y: Integer; State: TDragState; var Accept: Boolean);
> begin
>    Accept:=(Source=TelegramaFis);
> end;
> 
> //Drag drop handler shared by all spinedits
> procedure TAjustesSortens.sortenDragDrop(Sender, Source: TObject; X,
>    Y: Integer);
> begin
>    With TelegramaFis do
>      TMySpinEdit(Sender).Value:=StrToInt(Cells[0,row]);
> end;

Bye

-- 
Luca Olivetti
Wetron Automatización S.A. http://www.wetron.es/
Tel. +34 93 5883004      Fax +34 93 5883007