keyPressEvent suddenly not firing



  • I have a program I have been working on for over a year. I have multiple forms, one being the Main Window. I made one change to the keyPressEvent method on one of the forms derived from QDialog and now all of a sudden the only form the keypress event works on is the main. All other forms it never fires. The only thing I changed was adding another case to my switch statement to handle a different keypress. Why this would break the keyPress event on all other forms except the main window is beyond me.

    I am grabbing the keyboard in the constructor for the form.



  • Update. When I created an object for one of my forms, I passed in "this" from the Main Window as the parent object. For some reason this breaks the keypress event in the child form.


  • Lifetime Qt Champion

    What key press event handling did you modify ?



  • @SGaist I modified the keyPressEvent handler in the on of my Dialog forms (not the main window). I wanted to add handling when the user presses the 8 key. In my reply I noted that I did also add passing "this" from the main window as the parent object of the dialog when I created the dialog object. When I removed that it started working again.

    The goal is when the users presses the 8 key, to close the Dialog and pass the key press back to the main window.


  • Lifetime Qt Champion

    In that case, shouldn't you rather handle that directly in the main window and use it as a filter on your dialog ?



  • @SGaist I don't understand the question, but here is the situation. The target system has 9 total keys. 1-8 and T. On most screens these keys have the same behavior. However, the 8 key on all screens but the Main Window causes the current screen to close then the Main Window needs to react as if it had focus with the 8 key was pressed.

    I just added code to search through the QWindowList returned by QApplication::topLevelWindows to find a pointer to the Main Window. I then use that pointer in the QApplication::sendEvent to send the 8 key press to it.

    What I am wondering is if it would work the same way if I do not call event->accept() when the 8 key is pressed and just close the current window?


  • Lifetime Qt Champion

    I meant Event Filters.

    So your MainWindow would be doing all the handling of the 8 key itself



  • @SGaist Not really because the current window has to close before the main window handles the 8 key. All the other windows are started using exec() method from the main screen.

    For example I create password screen object (a). I call a.exec() to actually show the screen.


  • Lifetime Qt Champion

    Well, that would be part of the logic of the filter: first step, close the dialog, second handle 8.

    In any case, your idea of not calling accept on the event should result it in being forward to your MainWindow


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