Something

### A custom item exampleimport sysimport gobjectimport gtkimport goocanvasclass CustomItem(goocanvas.ItemSimple, goocanvas.Item):#    __gtype_name__ = "CustomItem"#     __gproperties__ = {#         'title': (str, None, None, '', gobject.PARAM_READWRITE),#         'description': (str, None, None, '', gobject.PARAM_READWRITE),#         'can-focus': (bool, None, None, False, gobject.PARAM_READWRITE),#         'visibility-threshold': (float, None, None, 0, 10e6, 0, gobject.PARAM_READWRITE),#         'visibility': (goocanvas.ItemVisibility, None, None, goocanvas.ITEM_VISIBLE, gobject.PARAM_READWRITE),#         'pointer-events': (goocanvas.PointerEvents, None, None, goocanvas.EVENTS_NONE, gobject.PARAM_READWRITE),#         'transform': (goocanvas.TYPE_CAIRO_MATRIX, None, None, gobject.PARAM_READWRITE),#         }    def __init__(self, **kwargs):        self.bounds = goocanvas.Bounds()        self.view = None        self.parent = None        ## default values for properties        #self.title = None        #self.description = None        #self.can_focus = False        #self.visibility = goocanvas.ITEM_VISIBLE        #self.visibility_threshold = 0.0        #self.pointer_events = goocanvas.EVENTS_NONE        #self.transform = None        ## chain to parent constructor        gobject.GObject.__init__(self, **kwargs)    def do_create_view(self, canvas_view, parent_view):        print "do_create_view"        assert self.view is None        self.view = self        return self    def do_set_parent(self, parent):        assert self.parent is None        self.parent = parent    def do_set_property(self, pspec, value):        if pspec.name == 'title':            self.title = value        elif pspec.name == 'description':            self.description = value        elif pspec.name == 'can-focus':            self.can_focus = value        elif pspec.name == 'visibility':            self.visibility = value        elif pspec.name == 'visibility-threshold':            self.visibility_threshold = value        elif pspec.name == 'pointer-events':            self.pointer_events = value        elif pspec.name == 'transform':            self.transform = value        else:            raise AttributeError, 'unknown property %s' % pspec.name            def do_get_property(self, pspec):        if pspec.name == 'title':            return self.title        elif pspec.name == 'description':            return self.description        elif pspec.name == 'can-focus':            return self.can_focus        elif pspec.name == 'visibility':            return self.visibility        elif pspec.name == 'visibility-threshold':            return self.visibility_threshold        elif pspec.name == 'pointer-events':            return self.pointer_events        elif pspec.name == 'transform':            return self.transform        else:            raise AttributeError, 'unknown property %s' % pspec.name    ## optional methods    def do_get_bounds(self):        return self.bounds    def do_get_item_view_at(self, x, y, cr, is_pointer_event, parent_is_visible):        return None    def do_set_parent_view(self, parent_view):        pass    ## mandatory methods    def do_update(self, entire_tree, cr):        raise NotImplementedError    def do_paint(self, cr, bounds, scale):        raise NotImplementedErrorgobject.type_register(CustomItem)class CustomRectItem(CustomItem):    def __init__(self, x, y, width, height, line_width, **kwargs):        CustomItem.__init__(self, **kwargs)        self.x = x        self.y = y        self.width = width        self.height = height        self.line_width = line_width    def do_update(self, entire_tree, cr):        half_lw = self.line_width/2        self.bounds.x1 = float(self.x - half_lw)        self.bounds.y1 = float(self.y - half_lw)        self.bounds.x2 = float(self.x + self.width + half_lw)        self.bounds.y2 = float(self.y + self.height + half_lw)        return self.bounds    def do_paint(self, cr, bounds, scale):        cr.rectangle(self.x, self.y, self.width, self.height)        cr.set_line_width(self.line_width)        cr.set_source_rgb(0, 0, 0)        cr.stroke()        return self.boundsdef main(argv):    window = gtk.Window()    window.set_default_size(640, 600)    window.show()    window.connect("destroy", lambda w: gtk.main_quit())        scrolled_win = gtk.ScrolledWindow()    scrolled_win.set_shadow_type(gtk.SHADOW_IN)    scrolled_win.show()    window.add(scrolled_win)        canvas = goocanvas.CanvasView()    canvas.set_size_request(600, 450)    canvas.set_bounds(0, 0, 1000, 1000)    canvas.show()    scrolled_win.add(canvas)        ## Create the canvas model    canvas_model = create_canvas_model()    canvas.set_model(canvas_model)    gtk.main()def create_canvas_model():    canvas_model = goocanvas.CanvasModelSimple()    root = canvas_model.get_root_item()    item = CustomRectItem(x=100, y=100, width=400, height=400, line_width=20)    root.add_child(item)    item = goocanvas.Text(text="Hello World",                          x=300, y=300,                          anchor=gtk.ANCHOR_CENTER,                          font="Sans 24")    root.add_child(item)    item.rotate(45, 300, 300)    return canvas_modelif __name__ == "__main__":    main(sys.argv)