No Error on Xcb_Grab_Key But Event Loop Not Catching (Global Hotkey)

No error on xcb_grab_key but event loop not catching (Global Hotkey)

Figured it out at long last!! Ah figured this one out! I was using XCB_MOD_MASK_ANY and this constant works on Debian but not on Ubuntu, which is what I was using to test. I switched that up to use num lock, caps lock etc and now it works! :)

ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_LOCK, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC); // caps lock
ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_2, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC); // num lock
ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_LOCK | ostypes.CONST.XCB_MOD_MASK_2, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC); // caps lock AND num lock

that was very very crazy i had no idea the XCB_MOD_MASK_ANY constant didnt work on Ubuntu -

var rez_grab = ostypes.API('xcb_grab_key')(conn, 1, screens.data.contents.root, ostypes.CONST.XCB_MOD_MASK_ANY, keycodesArr[j], ostypes.CONST.XCB_GRAB_MODE_ASYNC, ostypes.CONST.XCB_GRAB_MODE_ASYNC);

I also tried @n.m's code. On ubuntu it didnt work, but worked on debian -

#include <xcb/xcb.h>
#define XK_LATIN1
#include <xcb/xcb_keysyms.h>
#include <X11/keysymdef.h>
#include <stdio.h>
#include <stdlib.h>

int
main ()
{
  xcb_connection_t *conn;

  conn = xcb_connect (NULL, NULL);

  xcb_key_symbols_t * keysyms = xcb_key_symbols_alloc(conn);

  xcb_keycode_t * keycodesPtr = xcb_key_symbols_get_keycode(keysyms, XK_space);

  const xcb_setup_t* setup = xcb_get_setup(conn);

  xcb_screen_iterator_t screens = xcb_setup_roots_iterator(setup);
  int screensCnt = screens.rem;

  for (int i=0; i<screensCnt; i++) {

      xcb_void_cookie_t rez_grab = xcb_grab_key(conn, 1, screens.data->root, XCB_MOD_MASK_ANY, keycodesPtr[0], XCB_GRAB_MODE_ASYNC, XCB_GRAB_MODE_ASYNC);

      const static uint32_t values[] = { XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_BUTTON_PRESS };

      xcb_change_window_attributes (conn, screens.data->root, XCB_CW_EVENT_MASK, values);

      xcb_screen_next(&screens);
  }

  xcb_flush(conn);

  // start event loop
  while (1) {
      xcb_generic_event_t *ev = xcb_wait_for_event(conn);

      if (ev && ((ev->response_type & ~0x80) == XCB_KEY_PRESS))
      {
          xcb_key_press_event_t *kp = (xcb_key_press_event_t *)ev;
          printf ("Got key press %d\n", (int)kp->event);
      }

      if (ev != NULL) {
          free(ev);
      }
  }

  return 0;
}

XCB event loop not getting any events

You don't just magically get all events by opening a connection. There's only very few messages any client will receive, such as client messages, most others will only be sent to a client if it explicitly registered itself to receive them.

And yes, that means you have to register them on each and every window, which involves both crawling the tree and listening for windows being created, mapped, unmapped and destroyed and registering on them as well.

However, I would reconsider whether

My goal is to get all events on the system.

isn't an A-B problem. Why do you "need" all events? What do you actually want to do?

xcb keyboard button masks meaning

Usually Mask1 is Alt or Meta, Mask2 is Num lock, Mask3 is AltGr, Mask4 is Win, and Mask5 is Scroll lock, but this varies between X implementations and/or keyboard models.

Source: my own computer running X11, and various bits and pieces of code lying around on the 'net. Not all of them are consistent, e.g. some say Mod1 is Alt and Mod4 is Meta.

X11 programs normally let users configure actions corresponding to Mask1 ... Mask5, and have them sort out which key sets which mask.

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