Getting system wide X11 events problems

[wandereq]

Hi,

I'm trying to do something similar to a taskbar application for capturing windows. I need to capture all X11 events (I'm mostly interested in CreateNotify/DestroyNotify etc). I created a CaptureApp class from QApplication so I can implement x11EventFilter and even QAbstractEventDispatcheer filter. Everything works ok (meaning I get correct x11 events codes for create/destroy window) till I create a new QWidget (a main application window for example. After the main window is created I still get event codes but they are changed, insted of CreateNotify/DestroyNotify I get a bunch of PropertyChanged codes.

I'm not sure what I'm doing wrong or why the x11Events are somehow modified as soon as I create a QWidget. Any clues ?

P.S. I'm also doing XSelectInput(dpy, rootId, SubstructureNotifyMask); to get all events from the root window and dpy display.

class CaptureApp: public QApplication
{
public:
        CaptureApp(int argc, char **argv);
        ~CaptureApp();
        bool x11EventFilter (XEvent *event);
        static bool customEventFilter(void *message);
private:
        QAbstractEventDispatcher *evInstance;
};

class CaptureApp: public QApplication
{
public:
        CaptureApp(int argc, char **argv);
        ~CaptureApp();
        bool x11EventFilter (XEvent *event);
        static bool customEventFilter(void *message);
private:
        QAbstractEventDispatcher *evInstance;
};

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CaptureApp::CaptureApp(int argc, char** argv): QApplication(argc, argv)
{
        evInstance = QAbstractEventDispatcher::instance();
        evInstance->setEventFilter((QAbstractEventDispatcher::EventFilter)customEventFilter);
}
 
 
CaptureApp::~CaptureApp()
{
 
}
 
bool CaptureApp::customEventFilter(void *message)
{
        XEvent *ev;
 
        ev = (XEvent *) message;
 
        if (ev->type == CreateNotify)
        {
                qDebug("[customEventFilter]: Window id 0x%.8lx created\n", ev->xcreatewindow.window);
        }
        return false;
}
 
bool CaptureApp::x11EventFilter(XEvent *event)
{
 
        if (event->type == CreateNotify)
        {
                qDebug("Window id 0x%.8lx created\n", event->xcreatewindow.window );
        }
 
        return false;
}

CaptureApp::CaptureApp(int argc, char** argv): QApplication(argc, argv)
{
        evInstance = QAbstractEventDispatcher::instance();
        evInstance->setEventFilter((QAbstractEventDispatcher::EventFilter)customEventFilter);
}


CaptureApp::~CaptureApp()
{

}

bool CaptureApp::customEventFilter(void *message)
{
        XEvent *ev;
             
        ev = (XEvent *) message;

        if (ev->type == CreateNotify)
        {
                qDebug("[customEventFilter]: Window id 0x%.8lx created\n", ev->xcreatewindow.window);
        }
        return false;
}

bool CaptureApp::x11EventFilter(XEvent *event)
{

        if (event->type == CreateNotify)
        {
                qDebug("Window id 0x%.8lx created\n", event->xcreatewindow.window );
        }
        
        return false;
}

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[tebrandt]

I know this is way too late to reply, but I just found this thread and I'm having the exact same problem. I found that if you run XSelectInput after the "show" call of the main widget, the system wide events start reappearing. I think when the main widget is shown the QWidget class makes an implicit call to XSelectInput that you have to override later. This is the function call I use after "show":

XSelectInput(QX11Info::display(), DefaultRootWindow(QX11Info::display()), SubstructureNotifyMask);

Thanks for posting this BTW, you gave me just enough info to get this online (I didn't know about XSelectInput til I read this).