Re: Howto handle win32 messages ?

[Aurelien Minet <a minet prim-time fr>]

Hi  Ken,

> Since I'm planning on adding DDE server functionality to my 
> GTK+ app, I also have a need to process Win32 messages that 
> GDK/GTK+ would otherwise ignore.
I am in the same case,  I got an ATL/COM  server runing  and I have got 
process the message it emits.

> Here is yet another idea: install an idle function that looks for 
> messages of interest with PeekMessage().  Here is what I have so 
> far:
>
> gboolean dde_idle(gpointer data)
> {
>    MSG msg;
>
>    if (PeekMessage(&msg, NULL, XTYP_CONNECT, XTYP_CONNECT, PM_NOREMOVE))
>    {
>        OutputDebugString("Received message XTYP_CONNECT!\n");
>    }
>    return(TRUE);
> }
>
>    ...  
>    g_idle_add(dde_idle, NULL);
>    ...
I have had this idea too, but  you need some idle time to be sure it 
will be call. So I drop it.

> Note how I'm limiting which messages I am looking for. In the
> example above I'm looking for a single message (XTYP_CONNECT).
> I tried peeking for all messages with 
>    PeekMessage(&msg, NULL, 0, 0, PM_NOREMOVE);
> and then I tried peeking for a smaller number of messages with
>    PeekMessage(&msg, NULL, WM_KEYFIRST, WM_KEYLAST, PM_NOREMOVE);
> but,  much to my surprise, both screwed up GTK+ message 
> processing in interesting ways.
>
> Why would peeking and not removing the messages screw up GTK's 
> message processing?  Another undocumented Microsoft "feature"
> in PeekMessage()? *sigh*
I think it could be better if you give the hWnd of the GTK main window 
instead of NULL.
But   TranslateMessage(&msg) or/and  DispatchMessage(&msg) before 
returning TRUE may prevent screwing up GTK+ messages , I am not sure.
It could be a problem with the GTK+ translation messages system.


Regards

Aurelien

Here is the solution I used with GTK+ 2.2.1 :
( There are some strange casts cause it's C++, they are't need in C)

WNDPROC OldWinProc=NULL; // a global var :\


/*in  my create_window  function which creates the main gtk window with 
menu ...*/
GtkWidget *window;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
....
return window;

/* in main()  */
...
window= create_window();
...
gtk_init(&argc, &argv);
...
HWND hWnd = (struct HWND__ *) gdk_win32_drawable_get_handle(  ( 
window->window ) );
change_WndProc(HWND hWnd);

gtk_widget_show (window);

gtk_main ();


void change_WndProc(HWND hWnd)
{
   OldWinProc= (WNDPROC) GetWindowLong(hWnd,GWL_WNDPROC);
   SetWindowLong(hWnd,GWL_WNDPROC,(LONG)(WNDPROC)MyWinProc);
}

LONG CALLBACK MyWinProc(HWND hWnd,UINT msg,WPARAM wParam,LPARAM lParam)
{

   switch( msg )
   {
            case WM_XXX :
            .......
            break;

            case MY_MESSAGE :
            .....
            break;
            default:
                return 
CallWindowProc((WNDPROC)OldWinProc,hWnd,msg,wParam,lParam);
   }

   return TRUE ; /*by default */
}



PS: As Tor Lillqvist wrote in a previous mail, GTK+ 2.2.2 will have a 
gdk_window_add_filter() function in order to handle messages. GTK+ 2.2.2 
is just out but I have time to test it (and compile it) .