// -*- c++ -*- /* $Id: object.ccg,v 1.6 2002/12/31 17:56:44 daniel Exp $ */ /* Copyright 1998-2002 The gtkmm Development Team * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Library General Public * License as published by the Free Software Foundation; either * version 2 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this library; if not, write to the Free * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include #include #include namespace Atk { /* AtkObject is actually an abstract base class. So if this wrap_new() * function is called, it means that no wrapper exists for the real C object. * The problem is that gail (the real accessibility implementation) is * currently not wrapped and will probably never be. Therefore, code like * in the following example is doomed to fail: * * Gtk::Image image ("icon.png"); * Glib::RefPtr accessible = Glib::RefPtr::cast_dynamic(image.get_accessible()); * accessible->set_image_description("my icon"); * * This would segfault, even though the accessible object _does_ implement * AtkImage. But Atk::Image is an interface class that can't be instantiated * as is. It needs an object. * * The solution is to instantiate a dummy object that implements all of the * ATK interfaces. Fortunately, ATK already provides us with such a thing, * AtkNoOpObject. All widget accessible objects are of this type if the gail * module is not loaded (which is the default). * * So what we do here is abusing Atk::NoOpObject to get around the lack of * C++ wrappers for gail. Instead of instantiating a useless instance of an * abstract base class, we just create a Atk::NoOpObject instance which can * be casted to any of the Atk interface classes. */ Glib::ObjectBase* Object_Class::wrap_new(GObject* object) { return new Atk::NoOpObject((AtkNoOpObject*) object); } } // namespace Atk