Re: Using data parameter for callback functions

[Tim Müller <zen18864 zen co uk>]

On Sunday 25 January 2004 18:00, Malek Naffati wrote:

> I've yet successfully been trying to pass a window handle to a callback
> function through the data parameter (snip)
>
> static gboolean cancel_button_pressed(GtkWidget *widget, gpointer data)
> {
>         gtk_widget_hide(data);
>         return TRUE;
> }
>
> This results in a segfault...
>
> The Address of data in cancel_button_pressed does not reference
> the parameter passed to it in  g_signal_connect. Why is this?
> Am I getting something wrong here.

You have to check the API reference to see what the callback function for a 
signal needs to look like:

  http://developer.gnome.org/doc/API/2.0/gtk/GtkWidget.html#GtkWidget-button-press-event

In your case, the callback needs to be

static gboolean
cancel_button_pressed (GtkWidget *w, GdkEventButton *bevent, gpointer data)
{
    gtk_widget_hide(GTK_WIDGET(data));
   ....
}

Also check out the Gtk+ Tutorial, esp. section 3.4:
 
   http://www.gtk.org/tutorial/
   http://www.gtk.org/tutorial/sec-events.html


Cheers
-Tim