https://stackoverflow.com/questions/53915298

main.py

from PyQt5 import QtCore, QtWidgets

class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self._gv = QtWidgets.QGraphicsView()
        self.setCentralWidget(self._gv)
        self._gv.viewport().installEventFilter(self)

    def eventFilter(self, obj, event):
        if obj is self._gv.viewport() and event.type() == QtCore.QEvent.MouseButtonDblClick:
            print(obj, event)
        return super(MainWindow, self).eventFilter(obj, event)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())