xcb_grab_key man page

xcb_grab_key — Grab keyboard key(s)

Synopsis

#include <xcb/xproto.h>

Request function

xcb_void_cookie_t xcb_grab_key(xcb_connection_t *conn, uint8_t owner_events, xcb_window_t grab_window, uint16_t modifiers, xcb_keycode_t key, uint8_t pointer_mode, uint8_t keyboard_mode);

Request Arguments

conn
The XCB connection to X11.
owner_events
If 1, the grab_window will still get the pointer events. If 0, events are not reported to the grab_window.
grab_window
Specifies the window on which the pointer should be grabbed.
modifiers

The modifiers to grab.

Using the special value XCB_MOD_MASK_ANY means grab the pointer with all possible modifier combinations.

key

The keycode of the key to grab.

The special value XCB_GRAB_ANY means grab any key.

pointer_mode

One of the following values:

XCB_GRAB_MODE_SYNC
The state of the keyboard appears to freeze: No further keyboard events are generated by the server until the grabbing client issues a releasing AllowEvents request or until the keyboard grab is released.
XCB_GRAB_MODE_ASYNC
Keyboard event processing continues normally.
keyboard_mode

One of the following values:

XCB_GRAB_MODE_SYNC
The state of the keyboard appears to freeze: No further keyboard events are generated by the server until the grabbing client issues a releasing AllowEvents request or until the keyboard grab is released.
XCB_GRAB_MODE_ASYNC
Keyboard event processing continues normally.

Description

Establishes a passive grab on the keyboard. In the future, the keyboard is actively grabbed (as for GrabKeyboard), the last-keyboard-grab time is set to the time at which the key was pressed (as transmitted in the KeyPress event), and the KeyPress event is reported if all of the following conditions are true:

The keyboard is not grabbed and the specified key (which can itself be a modifier key) is logically pressed when the specified modifier keys are logically down, and no other modifier keys are logically down.

Either the grab_window is an ancestor of (or is) the focus window, or the grab_window is a descendant of the focus window and contains the pointer.

A passive grab on the same key combination does not exist on any ancestor of grab_window.

The interpretation of the remaining arguments is as for XGrabKeyboard. The active grab is terminated automatically when the logical state of the keyboard has the specified key released (independent of the logical state of the modifier keys), at which point a KeyRelease event is reported to the grabbing window.

Note that the logical state of a device (as seen by client applications) may lag the physical state if device event processing is frozen.

A modifiers argument of AnyModifier is equivalent to issuing the request for all possible modifier combinations (including the combination of no modifiers). It is not required that all modifiers specified have currently assigned KeyCodes. A keycode argument of AnyKey is equivalent to issuing the request for all possible KeyCodes. Otherwise, the specified keycode must be in the range specified by min_keycode and max_keycode in the connection setup, or a BadValue error results.

If some other client has issued a XGrabKey with the same key combination on the same window, a BadAccess error results. When using AnyModifier or AnyKey, the request fails completely, and a BadAccess error results (no grabs are established) if there is a conflicting grab for any combination.

Return Value

Returns an xcb_void_cookie_t. Errors (if any) have to be handled in the event loop.

If you want to handle errors directly with xcb_request_check instead, use xcb_grab_key_checked. See xcb-requests(3) for details.

Errors

xcb_access_error_t
Another client has already issued a GrabKey with the same button/key combination on the same window.
xcb_value_error_t
TODO: reasons?
xcb_window_error_t
The specified window does not exist.

See Also

xcb-requests(3), xcb_grab_keyboard(3)

Author

Generated from xproto.xml. Contact xcb@lists.freedesktop.org for corrections and improvements.

Referenced By

xcb_key_press_event_t(3), xcb_motion_notify_event_t(3), xcb_ungrab_key(3).

xcb_grab_key_checked(3) is an alias of xcb_grab_key(3).

libxcb 1.12 X Version 11 XCB Requests