Mega Code Archive

 

Categories / Delphi / Graphic

 

How to prevent a control from Redrawing (Refreshing)

Title: How to prevent a control from Redrawing (Refreshing) procedure LockControl(c: TWinControl; bLock: Boolean); begin if (c = nil) or (c.Handle = 0) then Exit; if bLock then SendMessage(c.Handle, WM_SETREDRAW, 0, 0) else begin SendMessage(c.Handle, WM_SETREDRAW, 1, 0); RedrawWindow(c.Handle, nil, 0, RDW_ERASE or RDW_FRAME or RDW_INVALIDATE or RDW_ALLCHILDREN); end; end; procedure TForm1.Button1Click(Sender: TObject); begin LockControl(DBGrid1, True); try // do convoluted things to the grid finally LockControl(DBGrid1, False); end; end; A number of controls have a build-in way to do that, the BeginUpdate and EndUpdate methods. You often find these not on the control itself but on some object property that manages the controls data, e.g. for a TMemo you use Lines.BeginUpdate and Lines.EndUpdate. The EndUpdate automatically forces a redraw of the control.