Re: Using a TreeStore with a ComboBox

[Jef Driesen <jefdriesen hotmail com>]

Jonathon Jongsma wrote:
> On 6/21/07, Jef Driesen <jefdriesen hotmail com> wrote:
> > Using a treestore model with a combobox creates a nice dropdown list
> > with submenus. Inside each submenu, the parent item is shown with a
> > separator below to separate it from its children. I want to know how I
> > can hide this parent node, so I can only select leaf nodes (e.g items
> > without children).
> >
> > The model contains places that can be are arranged by the user in an
> > arbitrary hierarchy, to group related places together (for instance by
> > continent and/or country). This is very similar how files (my places)
> > can be arranged into directories (my hierarchy). But when the user needs
> > to select a place with the combobox, it doesn't make sense to be able to
> > select an item that is not a place.
>
> You could probably accomplish this fairly easily with TreeModelFilter
> (http://gtkmm.org/docs/gtkmm-2.4/docs/reference/html/classGtk_1_1TreeModelFilter.html)
> wrapping your existing treestore. You'd just need to provide a
> function which checks whether a node has children or not, and pass
> that function to TreeModelFilter::set_visible_func().  Hope that
> helps.

I tried a TreeModelFilter like this:

Glib::RefPtr<Gtk::TreeStore> store = Gtk::TreeStore::create(m_columns);
Glib::RefPtr<Gtk::TreeModelFilter> filter = Gtk::TreeModelFilter::create 
(store);
filter->set_visible_func (sigc::mem_fun(*this, &Example::on_model_visible
combo.set_model(filter);

bool
Example::on_model_visible (const Gtk:TreeModel::const_iterator& iter)
{
   return iter->children().empty();
}

But it doesn't work. Exactly the same tree structure is shown if the 
model is populated after the set_visible_func. Or the combobox is 
completely empty, if the tree is populated before that.