When you create a bitmap in a method, the memory allocated to the bitmap
itself is NOT freed automatically, only the POINTER that you declared in
your VAR clause is freed:
procedure TMyForm.DoSomething;
var
Bmp : TBitmap; { This is really a pointer to a TBitmap object. It is
created on the stack, and freed on exit. }
begin
Bmp := TBitmap.Create; { Now the actual TBitmap object gets allocated on
the heap. }
...
end; { At this stage Bmp is freed (from the stack), but the TBitmap it
points to (on the heap) is not freed. }
This is why you could then assign Result := Bmp in a function for instance
and pass the bitmap back out.
Similarly, this is why we would use try... finally to ensure the bitmap was
freed.
procedure TMyForm.DoSomething;
var
Bmp : TBitmap; { This is really a pointer to a TBitmap object. It is
created on the stack, and freed on exit. }
begin
Bmp := TBitmap.Create; { Now the actual TBitmap object gets allocated on
the heap. }
try
...
finally
Bmp.Free; { Frees the memory from the heap }
end;
end; { At this stage Bmp is freed (from the stack). }
Regards,
Andrew Cooke.
> -----Original Message-----
> From: Alistair George [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, February 16, 1999 6:52 AM
> To: Multiple recipients of list delphi
> Subject: [DUG]: Handles
>
> Folks after the following code uses the handle of Panel1, I cant get the
> panel back to a useable state - that it was initialised in:
> hWndC := capCreateCaptureWindowA('My Own Capture Window',
> WS_CHILD or
> WS_VISIBLE,
> 0, 0,
> panel1.Width, panel1.Height,
> panel1.Handle, 0);
> {now I null hWndC, but I would also like to re-instate the Panel as it was
> intialized}
> if hWndC <> 0 then begin
> SendMessage(hWndC, WM_CAP_DRIVER_DISCONNECT, 0, 0);
> hWndC := 0;
> end;
> {changing properties of panel1.bringtofront/visible/enabled dont effect.
> Nulling hWndC does not destroy the panel}
>
> Last question: if I create a bitmap in a subroutine the bitmap is cleared
> on exiting the routine right?? I dont have to bitmap.free before exiting??
> (why I ask is that I see some code written using subproceedures and the
> bitmap is freed prior to exiting.)
>
> ideas??
> Tks,
> Alistair+
---------------------------------------------------------------------------
New Zealand Delphi Users group - Delphi List - [EMAIL PROTECTED]
Website: http://www.delphi.org.nz
