替换qApp eventFilter中的QKeyEvents

Question

我正在尝试编写一个PyQt5应用程序，它可以捕获某些按键并将其替换为其他一些按键。由于我希望在整个应用程序中进行此替换，因此我知道(可能是错误的)我需要在qApp上使用事件过滤器。在四处寻找之后，我拼凑出了这个概念验证：

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt

# Keys to block
kmap = [Qt.Key_U,Qt.Key_I,Qt.Key_O,Qt.Key_P,Qt.Key_J,Qt.Key_K,Qt.Key_L,Qt.Key_M]

class Example(QtWidgets.QMainWindow):

    def __init__(self):
        super().__init__()
        self.initUI()

    # The simplest UI
    def initUI(self):               
        self.edit = QtWidgets.QTextEdit()

        QtWidgets.qApp.installEventFilter(self)

        self.setCentralWidget(self.edit)
        # Window placement 
        self.show()

    def sendkeys(self, char, modifier=Qt.NoModifier):
        event = QtGui.QKeyEvent(QtCore.QEvent.KeyPress, 0, modifier, char)
        QtCore.QCoreApplication.postEvent(self, event)
        event = QtGui.QKeyEvent(QtCore.QEvent.KeyRelease, 0, modifier, char)
        QtCore.QCoreApplication.postEvent(self, event)

    def eventFilter(self, obj, event):
        if type(event) == QtGui.QKeyEvent:
            print("Normal stroke %d of type %s to %s" % (event.key(), str(event.type()), str(obj)))
            if event.key() in kmap:
                if type(obj) == QtWidgets.QTextEdit and obj.type() == QtCore.QEvent.KeyPress:
                    sendkeys("c")
                return True
        return super().eventFilter(obj, event)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

不幸的是，这不起作用。完全没有。

首先，被阻塞和未被阻塞的键会产生不同的事件，即使我在日志记录后进行了过滤：

Normal stroke 66 of type 51 to <PyQt5.QtGui.QWindow object at 0x7ff4800af948>
Normal stroke 66 of type 51 to <PyQt5.QtWidgets.QTextEdit object at 0x7ff4800af8b8>
Normal stroke 66 of type 6 to <PyQt5.QtGui.QWindow object at 0x7ff4800af948>
Normal stroke 66 of type 6 to <PyQt5.QtWidgets.QTextEdit object at 0x7ff4800af8b8>
Normal stroke 66 of type 7 to <PyQt5.QtGui.QWindow object at 0x7ff4800af948>
Normal stroke 66 of type 7 to <PyQt5.QtWidgets.QTextEdit object at 0x7ff4800af8b8>
Normal stroke 66 of type 7 to <__main__.Example object at 0x7ff4800af828>
Normal stroke 77 of type 51 to <PyQt5.QtGui.QWindow object at 0x7ff4800af948>
Normal stroke 77 of type 6 to <PyQt5.QtGui.QWindow object at 0x7ff4800af948>
Normal stroke 77 of type 7 to <PyQt5.QtGui.QWindow object at 0x7ff4800af948>

其次，sendkeys不起作用--笔画永远不会出现。

我不太确定我误解了什么--有什么建议吗？

Answer 1

如果您的目标是替换已发送的击键，则必须将它们发送到同一对象，而不是将它们发送到窗口：

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtCore import Qt

# Keys to block
kmap = [Qt.Key_U,Qt.Key_I,Qt.Key_O,Qt.Key_P,Qt.Key_J,Qt.Key_K,Qt.Key_L,Qt.Key_M]

class Example(QtWidgets.QMainWindow):
    def __init__(self):
        super().__init__()
        self.initUI()

    # The simplest UI
    def initUI(self):               
        self.edit = QtWidgets.QTextEdit()
        self.setCentralWidget(self.edit)
        QtWidgets.qApp.installEventFilter(self)
        # Window placement 
        self.show()

    def sendkeys(self, obj, char, modifier=Qt.NoModifier):
        event = QtGui.QKeyEvent(QtCore.QEvent.KeyPress, 0, modifier, char)
        QtCore.QCoreApplication.postEvent(obj, event)
        event = QtGui.QKeyEvent(QtCore.QEvent.KeyRelease, 0, modifier, char)
        QtCore.QCoreApplication.postEvent(obj, event)

    def eventFilter(self, obj, event):
        if event.type() == QtCore.QEvent.KeyPress and isinstance(obj, QtWidgets.QTextEdit):
            print("Normal stroke %d of type %s to %s" % (event.key(), str(event.type()), str(obj)))
            if event.key() in kmap:
                self.sendkeys(obj, "c")
                return True
        return super().eventFilter(obj, event)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())