QAbstractNativeEventFilter not receive XCB_KEY_PRESS - c++

Question

I'm building a Qt application that process native xcb events. But cannot receive key press event or mouse events.
Below are my codes.
// myfilter.h
class MyFilter : public QObject, public QAbstractNativeEventFilter
{
Q_OBJECT
public:
explicit MyFilter(xcb_connection_t *conn, QObject *parent = nullptr);
~MyFilter();
virtual bool nativeEventFilter(const QByteArray &eventType, void *message,
long *result) override;
signals:
private:
xcb_connection_t *_conn;
xcb_window_t _rootWindow;
};
// myfilter.cpp
MyFilter::MyFilter(xcb_connection_t *conn, QObject *parent)
: QObject(parent)
{
this->_conn = conn;
xcb_screen_t *screen;
screen = xcb_setup_roots_iterator(xcb_get_setup(this->_conn)).data;
this->_rootWindow = screen->root;
qDebug() << "Root window: " << this->_rootWindow;
// xcb_grab_key(this->_conn, 1, screen->root, XCB_MOD_MASK_ANY, XCB_GRAB_ANY,
// XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC);
QCoreApplication::instance()->installNativeEventFilter(this);
}
MyFilter::~MyFilter()
{
xcb_disconnect(this->_conn);
}
bool MyFilter::nativeEventFilter(const QByteArray &eventType,
void *message, long *result)
{
if (eventType == "xcb_generic_event_t") {
xcb_generic_event_t *ev = static_cast<xcb_generic_event_t*>(message);
auto responseType = ev->response_type & ~0x80;
switch (responseType) {
case XCB_KEY_PRESS:
qDebug() << "XCB_KEY_PRESS";
break;
case XCB_EXPOSE:
qDebug() << "XCB_EXPOSE";
break;
case XCB_PROPERTY_NOTIFY:
{
xcb_property_notify_event_t *property_notify = (xcb_property_notify_event_t*)ev;
qDebug() << "XCB_PROPERTY_NOTIFY" << property_notify->atom << property_notify->window;
break;
}
case XCB_CLIENT_MESSAGE:
{
xcb_client_message_event_t *client_message = (xcb_client_message_event_t*)ev;
qDebug() << "XCB_CLIENT_MESSAGE" << client_message->window;
break;
}
default:
qDebug() << responseType;
break;
}
} else {
qDebug() << "Not a xcb_generic_event_t";
}
return false;
}
and
// main.cpp
#include <QApplication>
#include <QX11Info>
#include <xcb/xcb.h>
#include "myfilter.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
xcb_connection_t *conn = QX11Info::connection();
MyFilter myFilter(conn);
return a.exec();
}
I want to receive XCB_KEY_PRESS but when I run this application and press any key, it always prints 85 which is defined as XCB_ALLOC_NAMED_COLOR.
What is this event and why response_type reports this rather than XCB_KEY_PRESS?