python - 未调用 PyQt 窗口焦点事件

Question

我有一个 PyQt4 程序，我试图在窗口获得焦点时收到通知，遵循 QUndoGroup 文档中的建议:

It is the programmer's responsibility to specify which stack is active by calling QUndoStack::setActive(), usually when the associated document window receives focus.

但我有一个奇怪的问题，只有一个窗口实际上获得了 focusIn 和 focusOut 事件，而其他窗口要么在创建时只接收到一个事件，要么根本没有接收到它们。这是一个示例程序:

    #!/usr/bin/env python
    
    from PyQt4.QtCore import *
    from PyQt4.QtGui import *
    
    import sys
    
    class MyWindow(QMainWindow):
        def __init__(self):
            super(MyWindow, self).__init__()
            self.label = QLabel('Window')
            self.setCentralWidget(self.label)
            self.setFocusPolicy(Qt.StrongFocus)
    
        def focusInEvent(self, event):
            self.label.setText('Got focus')
    
        def focusOutEvent(self, event):
            self.label.setText('Lost focus')
    
    def main():
        app = QApplication(sys.argv)
        win1 = MyWindow()
        win2 = MyWindow()
        win1.show()
        win2.show()
        sys.exit(app.exec_())
    
    if __name__ == '__main__':
        main()

Answer 1

我实际上不太确定为什么它不起作用，可能是 qt 如何处理窗口之间的焦点转换的问题。无论如何，下面是您可能如何解决这个问题，我已经稍微更改了您的代码

from PyQt4.QtCore import *
from PyQt4.QtGui import *

import sys

class MyWindow(QMainWindow):
    def __init__(self, parent=None):
        super(MyWindow, self).__init__()
        self.label = QLabel('Window')
        self.setCentralWidget(self.label)
        self.setFocusPolicy(Qt.StrongFocus)

    def focusInEvent(self, event):
        self.label.setText('Got focus')

    def focusOutEvent(self, event):
        self.label.setText('Lost focus')

def changedFocusSlot(old, now):
    if (now==None and QApplication.activeWindow()!=None):
        print "set focus to the active window"
        QApplication.activeWindow().setFocus()

def main():
    app = QApplication(sys.argv)
    QObject.connect(app, SIGNAL("focusChanged(QWidget *, QWidget *)"), changedFocusSlot)

    win1 = MyWindow()
    win2 = MyWindow()
    win1.show()
    win2.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main() 

希望这对你有帮助，问候