PyQt5 Event Filter Object Detection

问题

I want to report the mouse position whenever I click on a point within a QGraphicsView widget.

class App(QMainWindow, Ui_MainWindow):

    def __init__(self, parent=None):
        super(App, self).__init__(parent)
        self.setupUi(self)

        self.graphicsView.viewport().installEventFilter(self)
        self.graphicsView_2.viewport().installEventFilter(self)

    def eventFilter(self, a0: 'QObject', a1: 'QEvent') -> bool:
        if a0 == self.graphicsView:
            if a1.type() == QtCore.QEvent.MouseButtonPress:
                mousePosition = a1.pos()
                print(mousePosition.x(), 261 - mousePosition.y())
                return True
            return False
        elif a0 == self.graphicsView_2:
            if a1.type() == QtCore.QEvent.MouseButtonPress:
                mousePosition = a1.pos()
                print(mousePosition.x(), 261 - mousePosition.y())
                return True
            return False
        return False

I only want it to report the mouse button when I press on one of the two QGraphicsView widgets I have listed. However, with this current code nothing is being triggered at any point. I assume a0 is never equal to the QGraphicsView widgets I want to compare it to, so I'm unsure how to make this trigger when I want it to.

回答1:

The QGraphicsView inherits from QAbstractScrollArea so the widget you click on is not the QGraphicsView but in its viewport(). And that seems to be understood because you install the event filter in the viewport() so "a0" will never be the QGraphicsView but its viewport(). Also as you compare objects it is better to use "is".

Considering the above, the solution is:

if a0 is self.graphicsView.viewport():

if a0 is self.graphicsView_2.viewport():

来源：https://stackoverflow.com/questions/59148443/pyqt5-event-filter-object-detection