XGRABDEVICE

Section: \ \& (3)
Updated: 03/09/2013
Index Return to Main Contents

---

 

NAME

XGrabDevice, XUngrabDevice - grab/release the specified extension device  

SYNOPSIS

#include <X11/extensions/XInput.h>

int XGrabDevice( Display *display,
                 XDevice* device,
                 Window grab_window,
                 Bool owner_events,
                 int event_count,
                 XEventClass *event_list,
                 int this_device_mode,
                 int other_devices_mode,
                 Time time);

int XUngrabDevice( Display *display,
                   XDevice *device,
                   Time time);

display
       Specifies the connection to the X server.

device
       Specifies the device to be grabbed or released.

grab_window
       Specifies the id of a window to be associated with the
       device.

owner_events
       Specifies a Boolean value that indicates whether
       theevents from the deviceare to be reported as usual or
       reported with respect to the grab windowif selected by
       the event list.

event_count
       Specifies the number of elements in the event_list
       array.

event_list
       Specifies a pointer to a list of event classes that
       indicates which eventsthe client wishes to receive.
       These event classes must have beenobtained specifying
       the device being grabbed.

this_device_mode
       Specifies further processing of events from this
       device.You can pass GrabModeSyncor GrabModeAsync.

other_devices_mode
       Specifies further processing of events from other
       devices.You can pass GrabModeSyncor GrabModeAsync.

time
       Specifies the time.You can pass either a timestamp or
       CurrentTime.

 

DESCRIPTION

The XGrabDevice request actively grabs control of the device
and generates DeviceFocusIn and DeviceFocusOut events. Further
device events are reported only to the grabbing
client.XGrabDevice overrides any active device grab by this
client. event_list is a pointer to a list of event classes.
This list indicates which events the client wishes to receive
while the grab is active. If owner_events is False, all
generated device events are reported with respect to
grab_window if selected. If owner_events is True and if a
generated device event would normally be reported to this
client, it is reported normally; otherwise, the event is
reported with respect to the grab_window, and is only reported
if specified in the event_list.

If the this_device_mode argument is GrabModeAsync, device event
processing continues as usual. If the device is currently
frozen by this client, then processing of device events is
resumed. If the this_device_mode argument is GrabModeSync, the
state of the device (as seen by client applications) appears to
freeze, and the X server generates no further device events
until the grabbing client issues a releasing XAllowDeviceEvents
call or until the device grab is released. Actual device
changes are not lost while the device is frozen; they are
simply queued in the server for later processing.

If other_devices_mode is GrabModeAsync, processing of events
from other devices is unaffected by activation of the grab. If
other_devices_mode is GrabModeSync, the state of all devices
except the grabbed device (as seen by client applications)
appears to freeze, and the X server generates no further events
from those devices until the grabbing client issues a releasing
XAllowDeviceEvents call or until the device grab is released.
Actual events are not lost while the devices are frozen; they
are simply queued in the server for later processing.

If the device is actively grabbed by some other client,
XGrabDevice fails and returns AlreadyGrabbed. If grab_window is
not viewable, it fails and returns GrabNotViewable. If the
device is frozen by an active grab of another client, it fails
and returns GrabFrozen. If the specified time is earlier than
the last-device-grab time or later than the current X server
time, it fails and returns GrabInvalidTime. Otherwise, the
last-device-grab time is set to the specified time (
CurrentTime is replaced by the current X server time).

If a grabbed device is closed by a client while an active grab
by that client is in effect, the active grab is released. If
the device is frozen only by an active grab of the requesting
client, it is thawed.

XGrabDevice can generate BadClass, BadDevice, BadValue, and
BadWindow errors.

The XUngrabDevice request releases the device and any queued
events if this client has it actively grabbed from either
XGrabDevice or XGrabDeviceKey. If other devices are frozen by
the grab, XUngrabDevice thaws them.XUngrabDevice does not
release the device and any queued events if the specified time
is earlier than the last-device-grab time or is later than the
current X server time. It also generates DeviceFocusIn and
DeviceFocusOut events. The X server automatically performs an
UngrabDevice request if the event window for an active device
grab becomes not viewable.

XUngrabDevice can generate a BadDevice error.

 

DIAGNOSTICS

BadDevice
       An invalid device was specified. The specified device
       does not exist or has not been opened by this client via
       XOpenInputDevice. This error may also occur if the
       specified device is the X keyboard or X pointer device.

BadValue
       Some numeric value falls outside the range of values
       accepted by the request. Unless a specific range is
       specified for an argument, the full range defined by the
       argument's type is accepted. Any argument defined as a
       set of alternatives can generate this error.

BadWindow
       A value for a Window argument does not name a defined
       Window.

 

SEE ALSO

XAllowDeviceEvents(3), XGrabDeviceButton(3), XGrabDeviceKey(3)

---

 

Index

NAME

SYNOPSIS

DESCRIPTION

DIAGNOSTICS

SEE ALSO