Getting access to the WindowProc function

[tpglemur]

Hi is there any way to get WindowProc messages in lazarus? I'm trying to do a wrapper for RichEdit but don't know how to catch the events.

Thanks

[Phil]

Hi is there any way to get WindowProc messages in lazarus? I'm trying to do a wrapper for RichEdit but don't know how to catch the events.

Thanks

Felipe came up with a way of doing this on Windows. I don't recall where it's documented, but you might want to search the wiki.

I used his approach in the ported Orpheus o32vlop1.pas validation unit. You can look at what's involved there and see if that's what you have in mind.

http://wiki.lazarus.freepascal.org/OrphPort

Thanks.

-Phil

[tpglemur]

Thanks for the reply.

I tried overriding the TWinControl's WinProc procedure, it seems to work.

I'm not sure it'll work, but I'm planning to put the RichEdit on the TWinControl via CreateWindowEx, and I'm hoping that the WinProc will pick up the RichEdit's messages.

[tpglemur]

I think the solution is here: http://www.spotlight.de/zforen/dlp/m/dlp-1204925621-1167.html

The code is reproduced here for reference

Type
  TWndProc = Windows.WNDPROC;


Var
  OldWnd: TWndProc = nil;

function StandByNotify(Hnd: HWnd; Msg: UInt; WParam: Windows.WParam; LParam: Windows.LParam): LResult; stdcall;
begin
  showmessage('StandByNotify');
  result := Windows.CallWindowProc(OldWnd,Hnd,Msg,WParam,LParam);
end;

constructor TPlayer.Create(AOwner: TWinControl);
begin
  ...
  if not assigned(OldWnd) then begin
    OldWnd := TWndProc(Windows.GetWindowLong(Application.MainForm.Handle,GWL_WNDPROC));
    Windows.SetWindowLong(Application.MainForm.Handle,GWL_WNDPROC,LongInt(@StandByNotify)); // hier entsteht der Fehler
  end;
  ...
end;

destructor TPlayer.Destroy;
begin
  if Assigned(OldWnd) then
    Windows.SetWindowLong(Application.MainForm.Handle,GWL_WNDPROC,LongInt(OldWnd));
  OldWnd := nil;
  ...
end;

Das verursacht eien Fehler ('External: SIGSEGV') in

function TWinControl.HandleAllocated : Boolean;
begin
  HandleAllocated := (FHandle <> 0);
end;



Thanks to the author