Allow to override event processing of DotWidget.

Don't use fancy GTK+ events/signals, just allow subclasses of DotWidget
to override on_click() method and then inject instance into DotWindow.

xdot.py

@@ -1770,20 +1770,33 @@ def is_click(self, event, click_fuzz=4, click_timeout=1.0):
  return (time.time() < self.presstime + click_timeout
  and math.hypot(deltax, deltay) < click_fuzz)
 
+ def on_click(self, element, event):
+ """Override this method in subclass to process
+ click events. Note that element can be None
+ (click on empty space)."""
+ return False
+
  def on_area_button_release(self, area, event):
  self.drag_action.on_button_release(event)
  self.drag_action = NullAction(self)
- if event.button == 1 and self.is_click(event):
- x, y = int(event.x), int(event.y)
- url = self.get_url(x, y)
- if url is not None:
- self.emit('clicked', unicode(url.url), event)
- else:
- jump = self.get_jump(x, y)
- if jump is not None:
- self.animate_to(jump.x, jump.y)
+ x, y = int(event.x), int(event.y)
+ if self.is_click(event):
+ el = self.get_element(x, y)
+ print "clicked element:", el
+ if self.on_click(el, event):
+ return True
+
+ if event.button == 1:
+ url = self.get_url(x, y)
+ if url is not None:
+ self.emit('clicked', unicode(url.url), event)
+ else:
+ jump = self.get_jump(x, y)
+ if jump is not None:
+ self.animate_to(jump.x, jump.y)
+
+ return True
 
- return True
  if event.button == 1 or event.button == 2:
  return True
  return False
@@ -1863,7 +1876,7 @@ class DotWindow(gtk.Window):
 
  base_title = 'Dot Viewer'
 
- def __init__(self):
+ def __init__(self, widget=None):
  gtk.Window.__init__(self)
 
  self.graph = Graph()
@@ -1875,7 +1888,7 @@ def __init__(self):
  vbox = gtk.VBox()
  window.add(vbox)
 
- self.widget = DotWidget()
+ self.widget = widget or DotWidget()
 
  # Create a UIManager instance
  uimanager = self.uimanager = gtk.UIManager()