Source Code for Module _Framework.Layer

  1  #Embedded file name: /Users/versonator/Hudson/live/Projects/AppLive/Resources/MIDI Remote Scripts/_Framework/Layer.py 
  2  """ 
  3  Module implementing a way to resource-based access to controls in an 
  4  unified interface dynamic. 
  5  """ 
  6  from Util import nop 
  7  from itertools import repeat, izip 
  8  from Resource import ExclusiveResource 
  9   
 10 -class LayerError(Exception): 
 11      pass 
 12   
 13   
 14 -class UnhandledControlError(LayerError): 
 15      pass 
 16   
 17   
 18 -class Layer(ExclusiveResource): 
 19      """ 
 20      A layer provides a convenient interface to control resources. In a 
 21      layer, you can group several controls by name.  The layer itself 
 22      is an exclusive resource.  When grabbing the layer, it will try to 
 23      grab all controls and will forward them to its own owner when he 
 24      receives them, and will take them from him when they are 
 25      release. The layer with give and take away the controls from its 
 26      client using methods of the form:: 
 27       
 28          client.set[control-name](control) 
 29       
 30      Where [control-name] is the name the control was given in this 
 31      layer.  This way, layers are a convenient way to provide controls 
 32      to components indirectly, with automatic handling of competition 
 33      for them. 
 34      """ 
 35   
 36 -    def __init__(self, *a, **controls): 
 37          super(Layer, self).__init__(*a) 
 38          self._layer_owner = None 
 39          self._priority = None 
 40          self._name_to_controls = dict(izip(controls.iterkeys(), repeat(None))) 
 41          self._control_to_names = dict() 
 42          for name, control in controls.iteritems(): 
 43              self._control_to_names.setdefault(control, []).append(name) 
 44   
 45 -    def _get_priority(self): 
 46          return self._priority 
 47   
 48 -    def _set_priority(self, priority): 
 49          if priority != self._priority: 
 50              self._priority = priority 
 51              if self._layer_owner: 
 52                  self.grab(self._layer_owner) 
 53   
 54      priority = property(_get_priority, _set_priority) 
 55   
 56 -    def __getattr__(self, name): 
 57          """ Provides access to controls """ 
 58          try: 
 59              return self._name_to_controls[name] 
 60          except KeyError: 
 61              raise AttributeError 
 62   
 63 -    def set_control_element(self, control, grabbed): 
 64          """ 
 65          Client interface of the ControlElement resource. Please do not 
 66          call this method directly, nor use a layer to grab controls 
 67          directly -- do it implicitly by grabing the layer. 
 68          """ 
 69          if not self._layer_owner: 
 70              raise AssertionError 
 71              raise control in self._control_to_names or AssertionError, 'Control not in layer.' 
 72              owner = self._layer_owner 
 73              names = self._control_to_names[control] 
 74              control = grabbed or None 
 75          for name in names: 
 76              try: 
 77                  handler = getattr(owner, 'set_' + name) 
 78              except AttributeError: 
 79                  if name[0] != '_': 
 80                      raise UnhandledControlError, 'Component %s has no handler for control %s' % (str(owner), name) 
 81                  else: 
 82                      handler = nop 
 83   
 84              handler(control) 
 85              self._name_to_controls[name] = control 
 86   
 87 -    def grab(self, client, *a, **k): 
 88          if client == self.owner: 
 89              self.on_grab(client, *a, **k) 
 90              return True 
 91          return super(Layer, self).grab(client, *a, **k) 
 92   
 93 -    def on_grab(self, client, *a, **k): 
 94          """ Override from ExclusiveResource """ 
 95          self._layer_owner = client 
 96          for control in self._control_to_names.iterkeys(): 
 97              k.setdefault('priority', self._priority) 
 98              control.resource.grab(self, *a, **k) 
 99   
100 -    def on_release(self, client): 
101          """ Override from ExclusiveResource """ 
102          for control in self._control_to_names.iterkeys(): 
103              control.resource.release(self) 
104   
105          self._layer_owner = None 
106