[FIXED] How to contol KeyEvent in Qt

Issue

With the window declared with CustomWidget as super class: class App(CustomWidget) hitting Alt+A properly prints 'keyPressEvent: Alt + a' message.

But the KeyEvent functionality is broken when the CustomWidget is assigned to window with setCentralWidget() or is set with layer.addWidget(widget). What is missing in a code?

from PyQt4 import QtCore, QtGui

class CustomWidget(QtGui.QWidget):
    def __init__(self, parent):
        QtGui.QWidget.__init__(self, parent=parent)

    def keyPressEvent(self, event):
        if event.modifiers() == QtCore.Qt.AltModifier:
            if event.key() == QtCore.Qt.Key_A:
                print 'keyPressEvent: Alt + a'
        # super(CustomWidget, self).keyPressEvent(event)

class App(QtGui.QMainWindow):
    def __init__(self, parent=None):
        QtGui.QMainWindow.__init__(self, parent=parent) 
        centralWidget = CustomWidget(self) 

        self.setCentralWidget(centralWidget)

        mainLayout=QtGui.QVBoxLayout()
        centralWidget.setLayout(mainLayout)

        widget = CustomWidget(self)
        mainLayout.addWidget(widget)

if __name__ == "__main__":
    app = QtGui.QApplication(sys.argv)
    w = App()
    w.show()
    sys.exit(app.exec_())

Solution

The widget must have focus to receive the event. Make sure you call setFocusPolicy() to have the CustomWidget accept and maintain focus after creating the window.

QWidget, keyPressEvent

QWidget, setFocusPolicy

Answered By - PowerGlove