Re: How to add a custom cell renderer to a Gtk::IconView

[Todor Todorov <ttodorov gmx net>]

Thanks for the reply. The only thing I don't know how to do is how to 
adapt the C/gtk+ renderer to the gtkmm/sigc signal-slot mechanism. My 
custom renderer has a vfunc declared in the class as:

void ( *toggled )( GtkCellRendererThumb* renderer, gchar* path, gpointer 
data );

I obviously need it in order to tell the model when a thumbnail in my 
icon view has been permanently selected via its checkbox. I tried the 
following:
    ...
    Gtk::IconView *browser = 0;
    builder->get_widget( "browser", browser );
    {
        GtkIconView *view = browser->gobj();
        GtkCellRenderer *cell = gtk_cell_renderer_thumb_new();
        gtk_cell_layout_pack_start( GTK_CELL_LAYOUT( view ), cell, FALSE );
        g_object_set( cell, "thumb-checkable", TRUE, "xpad", 2, "ypad", 
2, NULL );
        gtk_cell_layout_set_attributes( GTK_CELL_LAYOUT( view ), cell,
                                        "thumb-name", 0, "thumb-date", 1,
                                        "thumb-image", 2, 
"thumb-checked", 3,
                                        "thumb-duplicate", 4, NULL );
        g_signal_connect( G_OBJECT( cell ), "toggled", G_CALLBACK( 
&MainWindow::on_thumbnail_checked ), NULL );
    }
    browser->set_model( thumblist );
    ...

The callback is a member function declared as


Everything works up to the call of

On 11/20/2009 12:32 AM, Jos Alburquerque wrote:
> On Tue, 2009-11-17 at 22:58 -0500, Todor Todorov wrote:
>    
> > I need to clarify. What I tried was:
> >
> > Glib::RefPtr<Gtk::CellLayout>  cl = Glib::wrap( GTK_CELL_LAYOUT( my_icon_view.gobj() ) );
> >
> >
> > And the error was: "Glib::wrap_auto_interface(): The C++ instance
> > (N3Gtk8IconViewE) does not dynamic_cast to the interface."
> >
> >
> > On 11/17/2009 10:47 PM, Todor Todorov wrote:
> >      
> > > Hello list,
> > >
> > > I encountered the following problem: Under Gtk+ it is possible to have a
> > > GktIconView and cast it to a GtkCellLayout via the GTK_CELL_LAYOUT(obj)
> > > macro. Then I could add a custom cell renderer and set attributes to it.
> > >
> > > Now I have implemented my cell renderer in C++/Gtkmm and would like to
> > > add it to my Gtk::IconView. And since the class does not provide a
> > > pack_start() functionality like TreeView, I would have to go and find my
> > > own way to do it...
> > >
> > > The first problem is that the IconView class does not inherit (in the
> > > traditional C++ way) from Gtk::CellLayout. Second, the
> > > reinterpret_cast<>  did not work either. There is no function in the
> > > Gtk::IconView API that lets me convert to a CellLayout, or in the
> > > Gtk::CellLayout API to create it from an IconView... Third, I tried to
> > > do something like
> > >
> > > Gtk::CellLayout *cl = Glib::wrap( GTK_CELL_LAYOUT( my_icon_view.gobj() ) );
> > > cl->pack_start( renderer, false );
> > > cl->add_attribute( renderer->property_blah(), columns.blah );
> > > ....
> > >
> > > While it compiles, the application crashed with a reinterpret_cast
> > > failure reported. The only thing that worked so far was to take my Gtk+
> > > implementation of the renderer, add it to my project and create a
> > > GtkIconView, cast it to GTK_CELL_LAYOUT, add the renderer with
> > > properties, and at the end wrap it into a Gtk::IconView and work from
> > > there as it were pure Gtkmm.
> > >
> > > I wonder though, is this the best way? I would like to not handle Gtk+
> > > objects directly in my code. Can anyone make a suggestion as to how to
> > > add a custom cell renderer to a Gtk::IconView in a "best practice"
> > > approach? Your help and time are greatly appreciated.
> > >        
> The problem is that Gtk::IconView does not implement the Gtk::CellLayout
> interface because the change was done in Gtk+ at a time when gtkmm could
> not break ABI (I think searching on the list will provide more info).
> For now you're probably doing it the right way until the change can be
> made to gtkmm.
>
>