py/qobserver.py

   1 #!/usr/bin/env python
   2 from PyQt4.QtCore import QObject
   3 from PyQt4.QtCore import SIGNAL
   4 from PyQt4.QtGui import QSpinBox, QPixmap, QTextEdit, QLineEdit
   5
   6 from observer import Observer
   7
   8 class QObserver (Observer, QObject):
   9
  10         def __init__ (self, model, view):
  11                 Observer.__init__ (self)
  12                 QObject.__init__ (self)
  13
  14                 self.model = model
  15                 self.view = view
  16                 model.add_observer (self)
  17
  18                 self.__actions= {}
  19                 self.__callbacks = {}
  20                 self.__model_to_view = {}
  21                 self.__view_to_model = {}
  22
  23         def __del__ (self):
  24                 self.model.remove_observer (self)
  25                 self.model = None
  26                 self.view = None
  27
  28                 del self.__actions
  29                 del self.__model_to_view
  30                 del self.__view_to_model
  31
  32         def connect (self, obj, signal_str, *args):
  33                 '''Convenience function so that subclasses do not have
  34                 to import QtCore.SIGNAL.'''
  35                 signal = signal_str
  36                 if type (signal) is str:
  37                         signal = SIGNAL (signal)
  38                 return QObject.connect ( obj, signal, *args)
  39
  40         def SLOT (self, *args):
  41                 '''Default slot to handle all Qt callbacks.
  42                 This method delegates to callbacks from add_signals.'''
  43
  44                 widget = self.sender()
  45                 sender = str (widget.objectName())
  46
  47                 if sender in self.__callbacks:
  48                         model = self.__callbacks[sender][0]
  49                         callback = self.__callbacks[sender][1]
  50                         callback (model, *args)
  51
  52                 elif sender in self.__view_to_model:
  53                         model = self.__view_to_model[sender][0]
  54                         model_attr = self.__view_to_model[sender][1]
  55                         if isinstance (widget, QTextEdit):
  56                                 value = str (widget.toPlainText())
  57                                 model.set (model_attr, value)
  58                         elif isinstance (widget, QLineEdit):
  59                                 value = str (widget.text())
  60                                 model.set (model_attr, value)
  61                         else:
  62                                 print ("SLOT(): Unknown widget:",
  63                                                 sender, widget)
  64
  65         def add_signals (self, signal_str, *objects):
  66                 '''Connects object's signal to the QObserver.'''
  67                 for obj in objects:
  68                         self.connect (obj, signal_str, self.SLOT)
  69
  70         def add_callbacks (self, model, callbacks):
  71                 '''Registers callbacks that are called in response to GUI events.'''
  72                 for sender, callback in callbacks.iteritems():
  73                         self.__callbacks[sender] = ( model, callback )
  74
  75         def model_to_view (self, model, model_attr, *widget_names):
  76                 '''Binds model attributes to qt widgets (model->view)'''
  77                 self.add_subject (model, model_attr)
  78                 self.__model_to_view[model_attr] = widget_names
  79                 for widget_name in widget_names:
  80                         self.__view_to_model[widget_name] = (model, model_attr)
  81
  82         def add_actions (self, model, model_attr, callback):
  83                 '''Register view actions that are called in response to
  84                 view changes. (view->model)'''
  85                 self.add_subject (model, model_attr)
  86                 self.__actions[model_attr] = callback
  87
  88         def subject_changed (self, model, attr, value):
  89                 '''Sends a model attribute to the view (model->view)'''
  90                 if attr in self.__model_to_view:
  91                         for widget_name in self.__model_to_view[attr]:
  92                                 widget = getattr (self.view, widget_name)
  93                                 if isinstance (widget, QSpinBox):
  94                                         widget.setValue (value)
  95                                 elif isinstance (widget, QPixmap):
  96                                         widget.load (value)
  97                                 elif isinstance (widget, QTextEdit):
  98                                         widget.setText (value)
  99                                 elif isinstance (widget, QLineEdit):
 100                                         widget.setText (value)
 101                                 else:
 102                                         print ('subject_changed(): '
 103                                                         + 'Unknown widget:',
 104                                                         widget_name, widget)
 105
 106                 if attr not in self.__actions: return
 107                 widgets = []
 108                 if attr in self.__model_to_view:
 109                         for widget_name in self.__model_to_view[attr]:
 110                                 widget = getattr (self.__view, widget_name)
 111                                 widgets.append (widget)
 112                 # Call the model callback w/ the view's widgets as the args
 113                 self.__actions[attr] (model, *widgets)