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 connect (self, obj, signal_str, *args):
  24                 '''Convenience function so that subclasses do not have
  25                 to import QtCore.SIGNAL.'''
  26                 signal = signal_str
  27                 if type (signal) is str:
  28                         signal = SIGNAL (signal)
  29                 return QObject.connect ( obj, signal, *args)
  30
  31         def SLOT (self, *args):
  32                 '''Default slot to handle all Qt callbacks.
  33                 This method delegates to callbacks from add_signals.'''
  34
  35                 widget = self.sender()
  36                 sender = str (widget.objectName())
  37
  38                 if sender in self.__callbacks:
  39                         model = self.__callbacks[sender][0]
  40                         callback = self.__callbacks[sender][1]
  41                         callback (model, *args)
  42
  43                 elif sender in self.__view_to_model:
  44                         model = self.__view_to_model[sender][0]
  45                         model_attr = self.__view_to_model[sender][1]
  46                         if isinstance (widget, QTextEdit):
  47                                 value = str (widget.toPlainText())
  48                                 model.set (model_attr, value)
  49                         elif isinstance (widget, QLineEdit):
  50                                 value = str (widget.text())
  51                                 model.set (model_attr, value)
  52                         else:
  53                                 print ("SLOT(): Unknown widget:",
  54                                                 sender, widget)
  55
  56         def add_signals (self, signal_str, *objects):
  57                 '''Connects object's signal to the QObserver.'''
  58                 for obj in objects:
  59                         self.connect (obj, signal_str, self.SLOT)
  60
  61         def add_callbacks (self, model, callbacks):
  62                 '''Registers callbacks that are called in response to GUI events.'''
  63                 for sender, callback in callbacks.iteritems():
  64                         self.__callbacks[sender] = ( model, callback )
  65
  66         def model_to_view (self, model, model_attr, *widget_names):
  67                 '''Binds model attributes to qt widgets (model->view)'''
  68                 self.add_subject (model, model_attr)
  69                 self.__model_to_view[model_attr] = widget_names
  70                 for widget_name in widget_names:
  71                         self.__view_to_model[widget_name] = (model, model_attr)
  72
  73         def add_actions (self, model, model_attr, callback):
  74                 '''Register view actions that are called in response to
  75                 view changes. (view->model)'''
  76                 self.add_subject (model, model_attr)
  77                 self.__actions[model_attr] = callback
  78
  79         def subject_changed (self, model, attr, value):
  80                 '''Sends a model attribute to the view (model->view)'''
  81                 if attr in self.__model_to_view:
  82                         for widget_name in self.__model_to_view[attr]:
  83                                 widget = getattr (self.view, widget_name)
  84                                 if isinstance (widget, QSpinBox):
  85                                         widget.setValue (value)
  86                                 elif isinstance (widget, QPixmap):
  87                                         widget.load (value)
  88                                 elif isinstance (widget, QTextEdit):
  89                                         widget.setText (value)
  90                                 elif isinstance (widget, QLineEdit):
  91                                         widget.setText (value)
  92                                 else:
  93                                         print ('subject_changed(): '
  94                                                         + 'Unknown widget:',
  95                                                         widget_name, widget)
  96
  97                 if attr not in self.__actions: return
  98                 widgets = []
  99                 if attr in self.__model_to_view:
 100                         for widget_name in self.__model_to_view[attr]:
 101                                 widget = getattr (self.__view, widget_name)
 102                                 widgets.append (widget)
 103                 # Call the model callback w/ the view's widgets as the args
 104                 self.__actions[attr] (model, *widgets)