Re: Signals and marshaling

["Donna S. Martin" <donna omartin com>]

Your 'Quit' should be tied to your destroy
callback rather than your delete-event. 
If you are exiting within the delete-event
and not processing the destroy, then it
won't work :-).  
The delete_event callback does
whatever processing to ensure the user
really wants to close the app, then returns a 
FALSE.  This causes a destroy signal - I usually 
have a simple destroy callback which does gtk_main_quit():

void bye( GtkWidget *widget, gpointer user_data)
 {
   printf("Quitting now\n");
   /* And anything else I might need */
   gtk_main_quit();
 }

and is connected to both the destroy signal
and the activate of a 'Quit' menu item:

  gtk_signal_connect( GTK_OBJECT(quit_item), "activate", bye, NULL );
  gtk_signal_connect( GTK_OBJECT(top_widget), "delete-event", 
                     GTK_SIGNAL_FUNC(delete_handler), NULL );
  gtk_signal_connect( GTK_OBJECT(top_widget), "destroy", bye, NULL );


HTH,
Seems like this is in the tutorial
Donna
----- Original Message ----- 
From: Dmitry Ponomaryov <eagleowl comail ru>
To: <gtk-app-devel-list gnome org>
Sent: Wednesday, January 24, 2001 6:52 AM
Subject: Signals and marshaling


> Another question:
> I want that 'Quit' menu item close my application. But I already define
> callback for "delete_event". So put call to this call back into 'Quit'
> menu-item callback:
>
> void
> menu_close_cb( GtkWidget* widget,
>    gpointer   data )
> {
> delete_event_cb( NULL, NULL );
> }
>
> But this is ugly (am I right?) - I decide to make the following:
> 'Quit' menu item should emit "delete_event", which will be traped
> by application and so "delete_event_cb" will be called automaticly
> (self-acting). So:
>
> void
> menu_close_cb( GtkWidget* widget,
>    gpointer   data )
> {
> /* Parameter 'data' is main_window widget.  */
> gtk_signal_emit_by_name( GTK_OBJECT(data), "delete_event" );
>
> file://delete_event_cb( NULL, NULL );
> }
>
> But this dump core :-[ - something wrong with signal priorities?
> [one signal called during another].
>
> So to avoid core dump I define my marshaller and call back for menu
> item:
>
> gtk_signal_connect_full( GTK_OBJECT(close_item),
> "activate",
> NULL, /* No call-back function at all! */
> (GtkCallbackMarshal)(delete_event_marshal_NONE__NONE),
> GTK_WIDGET(main_window),
> NULL,
> FALSE,
> GTK_RUN_FIRST );
>
>
> void gcp_delete_event_marshal_NONE__NONE(GtkObject *object,
>     gpointer   data,
>     guint      n_args,
>     GtkArg    *args)
> {
> gtk_signal_emit_by_name( GTK_OBJECT(data), "delete_event" );
> }
>
>
> But this core dump too!!!
>
> > How can I transform emition of one signal to emition of other signal?
>  [or call one signal from another?]
>
> PS. Does "gtk_signal_emit_stop_by_name" stops propagation only for
>     for current signal with given name (and NOT all signals with given
>     name [may be in future])? If I am right may be I should use
> "gtk_signal_emit_stop_by_name"
>     to stop one signal propagation and after that emit another signal?
>     Something like:
>     (I haven't try the following example yet)
>
> void
> menu_close_cb( GtkWidget* widget,
>    gpointer   data )
> {
> /* Stop current signal propagation.  */
> gtk_signal_emit_stop_by_name( GTK_OBJECT(widget) /* menu item */,
> "activate" );
>
> /* Parameter 'data' is main_window widget.  */
> gtk_signal_emit_by_name( GTK_OBJECT(data), "delete_event" );
>
> file://delete_event_cb( NULL, NULL );
> }
>
> ---
> Dmitry Ponomaryov
>
>
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