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You are here: manpages

xcb_grab_keyboard

Section: XCB Requests (3)
Updated: libxcb 1.12
Index Return to Main Contents

NAME

xcb_grab_keyboard - Grab the keyboard

SYNOPSIS

#include <xcb/xproto.h>

Request function

: xcb_grab_keyboard_cookie_t xcb_grab_keyboard(xcb_connection_t *conn, uint8_t owner_events, xcb_window_t grab_window, xcb_timestamp_t time, uint8_t pointer_mode, uint8_t keyboard_mode);

Reply datastructure


typedef struct xcb_grab_keyboard_reply_t {
    uint8_t  response_type;
    uint8_t  status;
    uint16_t sequence;
    uint32_t length;
} xcb_grab_keyboard_reply_t;

Reply function

: xcb_grab_keyboard_reply_t *xcb_grab_keyboard_reply(xcb_connection_t *conn, xcb_grab_keyboard_cookie_t cookie, xcb_generic_error_t **e);

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.

time

Timestamp to avoid race conditions when running X over the network.

The special value XCB_CURRENT_TIME will be replaced with the current server time.

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.

REPLY FIELDS

response_type

The type of this reply, in this case XCB_GRAB_KEYBOARD. This field is also present in the xcb_generic_reply_t and can be used to tell replies apart from each other.

sequence

The sequence number of the last request processed by the X11 server.

length

The length of the reply, in words (a word is 4 bytes).

status

One of the following values:

XCB_GRAB_STATUS_SUCCESS: TODO: NOT YET DOCUMENTED.
XCB_GRAB_STATUS_ALREADY_GRABBED: TODO: NOT YET DOCUMENTED.
XCB_GRAB_STATUS_INVALID_TIME: TODO: NOT YET DOCUMENTED.
XCB_GRAB_STATUS_NOT_VIEWABLE: TODO: NOT YET DOCUMENTED.
XCB_GRAB_STATUS_FROZEN: TODO: NOT YET DOCUMENTED.

: TODO: NOT YET DOCUMENTED.

DESCRIPTION

Actively grabs control of the keyboard and generates FocusIn and FocusOut events. Further key events are reported only to the grabbing client.

Any active keyboard grab by this client is overridden. If the keyboard is actively grabbed by some other client, AlreadyGrabbed is returned. If grab_window is not viewable, GrabNotViewable is returned. If the keyboard is frozen by an active grab of another client, GrabFrozen is returned. If the specified time is earlier than the last-keyboard-grab time or later than the current X server time, GrabInvalidTime is returned. Otherwise, the last-keyboard-grab time is set to the specified time.

RETURN VALUE

Returns an xcb_grab_keyboard_cookie_t. Errors have to be handled when calling the reply function xcb_grab_keyboard_reply.

If you want to handle errors in the event loop instead, use xcb_grab_keyboard_unchecked. See xcb-requests(3) for details.

ERRORS

xcb_value_error_t: TODO: reasons?
xcb_window_error_t: The specified window does not exist.

EXAMPLE


/*
 * Grabs the keyboard actively
 *
 */
void my_example(xcb_connection_t *conn, xcb_screen_t *screen) {
    xcb_grab_keyboard_cookie_t cookie;
    xcb_grab_keyboard_reply_t *reply;

    cookie = xcb_grab_keyboard(
        conn,
        true,                /* report events */
        screen->root,        /* grab the root window */
        XCB_CURRENT_TIME,
        XCB_GRAB_MODE_ASYNC, /* process events as normal, do not require sync */
        XCB_GRAB_MODE_ASYNC
    );

    if ((reply = xcb_grab_keyboard_reply(conn, cookie, NULL))) {
        if (reply->status == XCB_GRAB_STATUS_SUCCESS)
            printf("successfully grabbed the keyboard\n");

        free(reply);
    }
}