Relevant code snippets. These aren't the complete methods, just those parts involving the check state (that's probably obvious):

The tree model:

Qt Code: 
  1. class TreeModel (QAbstractItemModel):
  2.  
  3.     def flags(self, index):
  4.         flags = Qt.ItemIsEnabled
  5.         item = self.get_item(index)
  6.         # ...
  7.         if index.column() is TreeModel.COLUMN_X:
  8.             if item.is_active():
  9.                 flags |= Qt.ItemIsSelectable | Qt.ItemIsUserCheckable
  10.         return flags
  11.  
  12.     def data(self, index, role):
  13.         data = QVariant()
  14.         item = self.get_item(index)
  15.         # ...
  16.         if role == Qt.CheckStateRole:
  17.             if index.column() is TreeModel.COLUMN_X:
  18.                 if item.is_active():
  19.                     data = QVariant(Qt.Checked)
  20.                 else:
  21.                     data = QVariant(Qt.Unchecked)
  22.         return data
  23.  
  24.     def setData(self, index, value, role):
  25.         status = False
  26.         item = self.get_item(index)
  27.         # ...
  28.         if role == Qt.CheckStateRole:
  29.             if index.column() is TreeModel.COLUMN_X:
  30.                 if not item.is_active():
  31.                     item.set_active(True)
  32.                 else:
  33.                     item.set_active(False)
  34.                 status = True
  35.                 self.emit(SIGNAL('dataChanged(QModelIndex,QModelIndex)', index, index)
  36.         return status
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The item delegate. Compare to the implementation of QItemDelegate.drawCheck. It differs only in two places:
  • The last line uses QStyle.PE_IndicatorRadioButton instead of QStyle.PE_IndicatorViewItemCheck
  • In the last two lines Instead of asking the private implementation for the owning widget (which can't be done), assume it's the tree view.



Qt Code: 
  1. class TreeRenderer(QItemDelegate):
  2.  
  3.     def drawCheck( self, painter, option, rect, state ):
  4.         '''Draw a radio button instead of a check button for mutually exclusive fields.'''
  5.         if not rect.isValid(): return
  6.         option.rect = rect
  7.         option.state &= ~QStyle.State_HasFocus
  8.         option.state |= {
  9.             Qt.Unchecked:        QStyle.State_Off,
  10.             Qt.PartiallyChecked: QStyle.State_NoChange,
  11.             Qt.Checked:          QStyle.State_On
  12.         }[ state ]
  13.         style = self.view.style() if self.view else QApplication.style()
  14.         style.drawPrimitive( QStyle.PE_IndicatorRadioButton, option, painter, self.view )
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