Delphi dbgrid continuous scrolling
I'm making an application that holds orders and prints invoices. I have some labels, tedits, tmemos, buttons, a datasource, an adotable, a popupmenu, and a dbgrid on my form.
When I build the program and scroll down th开发者_开发问答e dbgrid scrollbar, it scrolls after I release mouse button. But i want continuous scrolling.
Greetings
That's called thumb tracking. Derive a new class to override scrolling behavior. Example of using an interposer class:
type
TDBGrid = class(DBGrids.TDBGrid)
private
procedure WmVScroll(var Message: TWMVScroll); message WM_VSCROLL;
end;
TForm1 = class(TForm)
DBGrid1: TDBGrid;
..
implementation
procedure TDBGrid.WmVScroll(var Message: TWMVScroll);
begin
if Message.ScrollCode = SB_THUMBTRACK then
Message.ScrollCode := SB_THUMBPOSITION;
inherited;
end;
You can also replace the WindowProc
of the control if you don't want to derive a new class. All you need to do is to handle WM_VSCROLL
message. Here is an example how to do that.
Here is the other solution Sertac Akyuz mentioned without having to derive a new class from TDBGrid:
private
FOrgDBGridWndProc: TWndMethod;
procedure DBGridWndProc(var Msg: TMessage);
// ...
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
FOrgDBGridWndProc:= DBGrid1.WindowProc;
DBGrid1.WindowProc := DBGridWndProc;
end;
procedure TForm1.DBGridWndProc(var Msg: TMessage);
begin
if (Msg.Msg = WM_VSCROLL) and
(LongRec(Msg.wParam).Lo = SB_THUMBTRACK) then
begin
LongRec(Msg.wParam).Lo := SB_THUMBPOSITION;
end;
if Assigned(FOrgDBGridWndProc) then
FOrgDBGridWndProc(Msg);
end;
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