将XCB事件移植到XLib事件

Question

I'm using Qt 5.3.2 and an input handling library called gainput . Gainput can only accept XLib events and not XCB event structures. The big problem is that Qt is using xcb. Is there some "easy" way of porting xcb events to xlib events?

xcb_generic_event_t* xcbEvent = /* ... Poll/Wait for events ... */
XEvent* xlibEvent = GenericEventConvertionFunction(xcbEvent); // Something like this...

Answer 1

I don't think there is an easy way to get what you are looking for.

I'm not familiar with Qt, gainput or the nature of your project, but you can "convert" an existing Xlib connection into an xcb connecion . This way you can mix Xlib and XCB calls.

Only one of Xlib and XCB can manage the event queue. By default, Xlib does. To change this, call XSetEventQueueOwner() (from "Xlib-xcb.h") before making other calls.

Ideally you could inititally create a Xlib Display object, create a corresponding xcb_display, use the former for Qt and poll/wait on the latter and pass it gainput

One thing of note is that you can only convert one way.

How do you get a Display object given an xcb_connection_t object? You can't.

If this solution is not sufficient. I know of no good way to solve your problem. On the bright side Xlib and xcb events are more of less equivalent so a manual conversion wouldn't be too hard (the sizes of at least some events of are different so straight casting won't be enough)

EDIT

I believe someone had a similar question a few years ago. Apparently Display *display = QX11Info::display(); is a thing you can do