How can I subclass QGraphicsRectItem and QGraphicsEllipseItem in one class?

Question

I'm using Pyside2 and have a UI that uses QGraphicsView and a QGraphicsScene.

Right now I have two separate classes that subclass QGraphicsEllipseItem and QGraphicsRectItem like this:

class MyRectButton(QGraphicsRectItem):

    def contextMenuEvent(self, event):
        # custom context menu
        pass

    def custom_method_A(self):
        # add a custom method
        pass

    def custom_method_B(self):
        # add a custom method
        pass

class MyEllipseButton(QGraphicsEllipseItem):

    def contextMenuEvent(self, event):
        # custom context menu
        pass

    def custom_method_A(self):
        # add a custom method
        pass

    def custom_method_B(self):
        # add a custom method
        pass

Rather than have the redundant methods in both classes I'd like one class that can either be a rectangle or an ellipse like:

class MyButton():
    def __init__(self,shape='Ellipse'):
        pass

    def contextMenuEvent(self, event):
        # custom context menu
        pass

    def custom_method_A(self):
        # add a custom method
        pass

    def custom_method_B(self):
        # add a custom method
        pass

score 3 · Accepted Answer · answered Feb 26 '20 at 18:19

You can create a class that implements the common functionality and then the buttons inherit from the item and the common class:

from PyQt5 import QtCore, QtWidgets


class Foo:
    def contextMenuEvent(self, event):
        print("contextMenuEvent")

    def custom_method_A(self):
        print("custom_method_A")

    def custom_method_B(self):
        print("custom_method_B")


class MyRectButton(QtWidgets.QGraphicsRectItem, Foo):
    pass


class MyEllipseButton(QtWidgets.QGraphicsEllipseItem, Foo):
    pass


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    scene = QtWidgets.QGraphicsScene()
    view = QtWidgets.QGraphicsView(scene)

    it_rect = MyRectButton(QtCore.QRectF(-50, -30, 100, 100))
    it_ellipse = MyEllipseButton(QtCore.QRectF(50, 50, 100, 100))

    scene.addItem(it_rect)
    scene.addItem(it_ellipse)

    for it in (it_rect, it_ellipse):
        it.custom_method_A()
        it.custom_method_B()

    view.resize(640, 480)
    view.show()
    sys.exit(app.exec_())

How can I subclass QGraphicsRectItem and QGraphicsEllipseItem in one class?

1 Answers1