Re:I only want an onchange event of ttrackbar when the mouse is released
Quote
Rob wrote...
> I want to have an onchange event handler for the ttrackbar control, however,
> I only want to process this event once the mouse button is released (not
> while the slider is being moved).
> What is the best way to accomplish this? Can anyone provide an example?
Not sure if the code below is the best way but it does seems to work.
Note: - when you're only using this you will not be notified
when the user changes the trackbar by using the keyboard.
Another idea to prevent updating to often would be to (re)start
a timer (e.g. 1 sec) on every onchange and do the actually
updating in the ontimer event (and disable the timer again).
--
Pieter
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ComCtrls;
type
TMyTrackBar = class(TTrackbar)
published
property OnMouseDown;
property OnMouseUp;
end;
TForm1 = class(TForm)
procedure MyTrackBarMouseUp(Sender: TObject; Button: TMouseButton; Shift:
TShiftState; X, Y: Integer);
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
FMyTrackBar : TMyTrackBar;
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.MyTrackBarMouseUp(Sender: TObject; Button: TMouseButton; Shift:
TShiftState; X, Y: Integer);
begin
MessageDlg('Mouse up on position ' + IntToStr(FMyTrackBar.Position),
mtInformation, [mbOk], 0);
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
FMyTrackBar := TMyTrackBar.Create(Self);
with FMyTrackBar do
begin
Parent := Self;
Left := 10;
Top := 10;
OnMouseUp := MyTrackBarMouseUp;
end;
end;
end.
