Re: Finding widget from its name?

[jan <jan talentex demon co uk>]

Hi Tomas,

Now that is what I call a seriously good explanation! Thanks a lot.

/jan

tomas tuxteam de wrote:
> On Wed, Aug 16, 2006 at 06:02:27AM +0100, jan wrote:
> > > Progss wrote:
> > > > jan talentex demon co uk napisa?(a):
> > > > > Is there a function that allows one to search for a widget using its
> > > > > name or label? I'm using Glade 2 to design a window (just a basic
> > > > > input form), and each widget has a unique name. Unfortunately Glade
> > > > > doean't save any global pointers to the widgets; I can only assume
> > > > > that there must be another way to find the objects from within the
> > > > > callback functions. 
> > > > Absolutely, there is - glade_xml_get_widget
> > > >
> > > > e.g.
> > > > http://lists.ximian.com/pipermail/glade-users/2004-February/001790.html
> > > >
> > > > Regards,
> > > > Waldek
> > > Thanks!
> > >
> > > Now on to the next question: What if I wasn't using Glade? The gtk+
> > > documentation isn't exactly intuitive.
>
> Then the widgets don't have names ;-)
>
> Remember: you put names on the widgets with glade?
>
> But of course, there is nothing magical about it. If you peek into any
> glade project source, there is this pesky "support.c", and there you'll
> see:
>
> | GtkWidget*
> | lookup_widget                          (GtkWidget       *widget,
> |                                         const gchar     *widget_name)
> | {
> |   GtkWidget *parent, *found_widget;
> | 
> |   for (;;)
> |     {
> |       if (GTK_IS_MENU (widget))
> |         parent = gtk_menu_get_attach_widget (GTK_MENU (widget));
> |       else
> |         parent = widget->parent;
> |       if (!parent)
> |         parent = (GtkWidget*) g_object_get_data (G_OBJECT (widget), "GladeParentKey");
> |       if (parent == NULL)
> |         break;
> |       widget = parent;
> |     }
> | 
> |   found_widget = (GtkWidget*) g_object_get_data (G_OBJECT (widget),
> |                                                  widget_name);
> |   if (!found_widget)
> |     g_warning ("Widget not found: %s", widget_name);
> |   return found_widget;
> | }
>
> So what it's doing? First it climbs up the widget hierarchy along the
> parent lines (with some special cases for menus and some extra
> relationships set by glade with the help of a special "GladeParentKey"
> widget prop. When this grand-grand-grandpa widget is found, it is
> expected to contain a "database of widgets keyed by name" in its
> properties.
>
> Glade generates code to set up all this in interface.c, which looks
> more-or-less like
>
> |   /* Store pointers to all widgets, for use by lookup_widget(). */
> |   GLADE_HOOKUP_OBJECT_NO_REF (itlist_window, itlist_window, "itlist_window");
> |   GLADE_HOOKUP_OBJECT (itlist_window, vbox, "vbox");
> |   GLADE_HOOKUP_OBJECT (itlist_window, menu, "menu");
> |   GLADE_HOOKUP_OBJECT (itlist_window, menuitem1, "menuitem1");
> |   GLADE_HOOKUP_OBJECT (itlist_window, menu1, "menu1");
>
> (and on for many lines).
>
> It's an exercise for the reader to find out what the macro
> GLADE_HOOKUP_OBJECT does...
>
> HTH
> -- tomÃÂs