def __init__(self, doc: AbstractPage, parent=None):
super().__init__(parent)
self.view = SchView()
self.doc = doc
self.ctrl = Controller(doc=self.doc, view=self.view)
self.view.setCtrl(self.ctrl)
self.doc.undoStack.canUndoChanged.connect(self._onUndoChanged)
self.doc.undoStack.canRedoChanged.connect(self._onUndoChanged)
layout = QVBoxLayout()
layout.addWidget(self.view)
self.setLayout(layout)
