Source Code for Module library.pyjamas.EventController

  1  # Module for creating event handlers 
  2   
  3  ###################### 
  4  ## EventGenerator - mixin notification support class 
  5  # 
  6  # An EventGenerator mixin keeps multiple listener lists for custom events, 
  7  # and can fire notifications for the events 
  8  # 
  9  # To use this class, simply add the mixin class to the derived class definition: 
 10  ## class myClass(somebaseclass, EventGenerator): 
 11  # The derived class can define any number of custom events with a single call: 
 12  ## self.addListenedEvent("Foo") 
 13  # which will add the usual listener management methods to the class: 
 14  ## def addFooListener(self, listener)      # add a listener 
 15  ## def removeFooListener(self, listener)   # remove a listener 
 16  # as well as a method to send a custom event notification to the listeners: 
 17  ## def dispatchFooEvent(self, parms*)   # call listeners 
 18  # Listeners use this class in the usual way: 
 19  ## fooObj.addFooListener(self)      # will call self.onFoo() if I have one 
 20  # OR 
 21  ## fooObj.addFooListener(self.myFooHandler)      # will call self.myFooHandler() 
 22  # 
 23  # R. Newpol - 2009 
 24  ######################################### 
 25   
 26 -class EventGenerator(): 
 27 -    def _get_add_listener_func_name(self, ev): 
 28          return "add"+ev+"Listener" 
 29 -    def _get_remove_listener_func_name(self, ev): 
 30          return "remove"+ev+"Listener" 
 31 -    def _get_dispatch_func_name(self, ev): 
 32          return "dispatch"+ev+"Event" 
 33 -    def addListenedEvent(self, ev): 
 34          # create the EventListener with event-specific lists and funcs 
 35          global EventListener # is also a javascript global 
 36          el = EventListener(ev) 
 37          # add the "addXXXListener() method to ourself 
 38          attr_add = self._get_add_listener_func_name(ev) 
 39          setattr(self,attr_add,el.add_listener) 
 40          # add the "removeXXXListener()" method to ourself 
 41          attr_rem = self._get_remove_listener_func_name(ev) 
 42          setattr(self,attr_rem,el.rem_listener) 
 43          # add the "dispatchXXXEvent() method to ourself 
 44          attr_dsp = self._get_dispatch_func_name(ev) 
 45          setattr(self,attr_dsp,el.dispatch) 
 46   
 47  # EventListener objects provide event-specific listener list, 
 48  # as well as event-specific methods to add/remove listeners to the list, 
 49  # and dispatch event notifications 
 50  # This class is not instantiated directly; it is used by the EventGenerator class 
 51 -class EventListener(): 
 52 -    def __init__(self, ev): 
 53          self.ev = ev 
 54          self.listeners = [] 
 55 -    def add_listener(self, listener): 
 56          self.listeners.append(listener) 
 57 -    def rem_listener(self, listener): 
 58          self.listeners.remove(listener) 
 59      # listener objects should have a "onXX" event method 
 60 -    def dispatch(self, *args): 
 61          ev = "on"+self.ev 
 62          for listener in self.listeners: 
 63              if hasattr(listener,ev): 
 64                  getattr(listener,ev)(*args) 
 65              else: 
 66                  listener(*args) 
 67   
 68   
 69  # original Handler event class (unrelated to EventGenerator) 
 70 -class Handler(object): 
 71   
 72 -    def __init__(self, parent, event_type, *args, **kwargs): 
 73          if parent is None: 
 74              parent = self 
 75          self.parent = parent 
 76          self.event_type = event_type 
 77          self.listeners = {} 
 78          self.callback_fnname = "on%s" % event_type 
 79          self.extra_args = args 
 80          self.extra_kwargs = kwargs 
 81   
 82          # monkey-patch the parent with the callbacks 
 83          add_listener_fnname = "add%sListener" % event_type 
 84          del_listener_fnname = "remove%sListener" % event_type 
 85          listener = "_%sListeners" % event_type 
 86          on_event_name = "on%sEvent" % event_type 
 87          setattr(parent, listener, self) 
 88          setattr(parent, add_listener_fnname, self.addListener) 
 89          setattr(parent, del_listener_fnname, self.removeListener) 
 90          setattr(parent, on_event_name, self.onEvent) 
 91   
 92 -    def addListener(self, listener, *args, **kwargs): 
 93          args = args or () 
 94          kwargs = kwargs or {} 
 95          args = self.extra_args + args 
 96          kwargs.update(self.extra_kwargs) 
 97          self.listeners[listener] = (args, kwargs) 
 98   
 99 -    def removeListener(self, listener): 
100          self.listeners.pop(listener) 
101   
102 -    def onEvent(self, sender, *eventargs): 
103          for listener, args in self.listeners.items(): 
104              fn = getattr(listener, self.callback_fnname, listener) 
105              (args, kwargs) = args 
106              args = (sender,) + args + eventargs 
107              fn(*args, **kwargs) 
108