OS X + Qt: How to capture all key-press events in the entire GUI?

Question

I have a basic question about Qt and Mac OS X. If I define a QMainWindow class and define a keyPressEvent function as below, is it not supposed to enter this function whenever a key is pressed anywhere in the MyWindow? I have some problems with it under Linux, where I do not get the keypress events if certain widgets were focused on (list views or edit boxes), but at least I get it if I focus on a button and then press a key. Under Mac OS X I do not get any response at all.

class MyWindow(QMainWindow):    
    def keyPressEvent(self, event):
        key = event.key()
                
        if key == Qt.Key_F:
            print("pressed F key")

Any ideas (using Python with PySide)?

Asked By: P.R.

||

Source

Answer 1

When an event is used by a widget (e.g. an edit box), it is usually not propagated to its parent widgets, so you can’t get these events from the parent window. You should install an event filter on the main QApplication object. This way you will receive (and filter if you want) all events.

See Event filters.

Answered By: Pavel Strakhov

Answer 2

Solution based on Pavel’s answer:

import sys
from PySide.QtGui import *
from PySide.QtCore import * 


class basicWindow(QMainWindow):  

    def __init__(self):
        QMainWindow.__init__(self)

        self.edit = QLineEdit("try to type F", self)

        self.eF = filterObj(self)
        self.installEventFilter(self.eF)
        self.edit.installEventFilter(self.eF)
        self.show()

    def test(self, obj):
        print "received event", obj

class filterObj(QObject):
    def __init__(self, windowObj):
        QObject.__init__(self)
        self.windowObj = windowObj

    def eventFilter(self, obj, event):
        if (event.type() == QEvent.KeyPress):
            key = event.key()


            if(event.modifiers() == Qt.ControlModifier):
                if(key == Qt.Key_S):
                    print('standard response')

            else:                    
                if key == Qt.Key_F:
                    self.windowObj.test(obj)

            return True
        else:
            return False          


if __name__ == "__main__":
    app = QApplication(sys.argv)

    w = basicWindow()

    sys.exit(app.exec_())

_{This answer was posted as an edit to the question OS X + Qt: How to capture all key-press events in the entire GUI? by the OP P.R. under CC BY-SA 3.0.}

Answered By: vvvvv

OS X + Qt: How to capture all key-press events in the entire GUI?

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