C++ – How to pass X11 events to QDialog

How to pass X11 events to QDialog… here is a solution to the problem.

How to pass X11 events to QDialog

Currently I’m trying to pass system X11 events (on Linux) to an object I created. To do this, I install an eventFilter from my QApplication onto my object. This is valid because it gets all the events of the application. But I also need to pass object X11 events.

I went ahead and created an x11Event in my object in the hope that it would receive events from X11, but that wasn’t.

Is there a way to pass X11 events directly to my objects inside my application?


You can receive XEvent:: in the following ways

  • Use the filter function set by QAbstractEventDispatcher::instance()->setEventFilter() and it will receive all XEvents.
  • Use the filter function set by qApp->setEventFilter() and it will only receive events for the application.
  • Reimplementation of the virtual function QApplication::x11EventFilter
  • Reimplement the virtual function QWidget::x11Event for your top-level window (child widgets do not receive XEvent).

In this order. If any of these functions return true for any event, the next function will not receive that event.

Qt can also filter some events between these functions, such as QWidget::x11Event does not receive XKeyEvent (a function filtered by QInputContext::x11FilterEvent widget with keyboard focus).

For more details, you should check out the Qt source code: QEventDispatcher_ x11.cpp and functions QApplication:: x11ProcessEvent in QApplication_x11.cpp

So in most cases, if you only reimplement the x11Event function in the QDialog derived class, you should have received most of the XEvent. If you want your child parts to receive them as well, you can manually call their x11Event function from the reimplementation of QDialog::x11Event.

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