重写Qt MouseEvent，但仅当类变量为Tru时

Question

我有QComboBox，我希望用户能够锁定的索引。为此，我将QComboBox子类化，并将mousePressEvent重写为空，但在QComboBox的方法中

我尝试的两个问题：

• 我不知道如何在另一个类方法中重新定义mousePressEvent
• 如果不满足某个条件，我不知道如何恢复mousePressEvent的原始QComboBox行为。我的代码：

class MyComboBox(QtWidgets.QComboBox):
    def __init__(self, *args, **kwargs):
        super(self.__class__, self).__init__(*args, **kwargs)

    def lockSelection(self, bool=None):
        if bool:
            def mousePressEvent(self, *args, **kwargs):
                pass
        else:
            def mousePressEvent(self, *args, **kwargs):
                return QtWidgets.QComboBox.mousePressEvent(*args, **kwargs)

..... later

## I want this to get my overriden mousePressEvent 

MyComboBox.lockSelection(True)

## I want this to get the original mousePressEvent

MyComboBox.lockSelection(False)

Answer 1

如果要阻止继承的方法，只需重写该方法，并在必要时避免调用该方法：

from PyQt5 import QtWidgets


class MyComboBox(QtWidgets.QComboBox):
    def lockSelection(self, lock):
        self._lock_selection = lock

    def mousePressEvent(self, event):
        lock = getattr(self, "_lock_selection", False)
        if not lock:
            super(MyComboBox, self).mousePressEvent(event)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)

    w = QtWidgets.QWidget()

    combo = MyComboBox()
    combo.addItems(list("ABCD"))

    radio = QtWidgets.QCheckBox("Lock")
    radio.toggled.connect(combo.lockSelection)

    lay = QtWidgets.QHBoxLayout(w)
    lay.addWidget(radio)
    lay.addWidget(combo)
    w.resize(320, 60)
    w.show()
    sys.exit(app.exec_())

如果要避免继承，可以使用事件筛选器实现一个锁，以便在任何小部件中使用它：

from PyQt5 import QtCore, QtWidgets


class MouseLocker(QtCore.QObject):
    def __init__(self, widget):
        super(MouseLocker, self).__init__(widget)
        widget.installEventFilter(self)
        self._lock_selection = False

    def lockSelection(self, lock):
        self._lock_selection = lock

    def eventFilter(self, obj, event):
        if obj is self.parent() and event.type() == QtCore.QEvent.MouseButtonPress:
            return self._lock_selection
        return super(MouseLocker, self).eventFilter(obj, event)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)

    w = QtWidgets.QWidget()

    combo = QtWidgets.QComboBox()
    combo.addItems(list("ABCD"))
    locker = MouseLocker(combo)

    radio = QtWidgets.QCheckBox("Lock")
    radio.toggled.connect(locker.lockSelection)

    lay = QtWidgets.QHBoxLayout(w)
    lay.addWidget(radio)
    lay.addWidget(combo)
    w.resize(320, 60)
    w.show()
    sys.exit(app.exec_())