XGrabPointer(3X11) XLIB FUNCTIONS XGrabPointer(3X11)NAME
XGrabPointer, XUngrabPointer, XChangeActivePointerGrab-
grab the pointer
SYNTAX
int XGrabPointer(display, grab_window, owner_events,
event_mask, pointer_mode,
keyboard_mode, confine_to, cursor, time)
Display *display;
Window grab_window;
Bool owner_events;
unsigned int event_mask;
int pointer_mode, keyboard_mode;
Window confine_to;
Cursor cursor;
Time time;
XUngrabPointer(display, time)
Display *display;
Time time;
XChangeActivePointerGrab(display, event_mask, cursor,
time)
Display *display;
unsigned int event_mask;
Cursor cursor;
Time time;
ARGUMENTS
confine_to
Specifies the window to confine the pointer in
or None.
cursor Specifies the cursor that is to be displayed
during the grab or None.
display Specifies the connection to the X server.
event_mask
Specifies which pointer events are reported to
the client. The mask is the bitwise inclusive
OR of the valid pointer event mask bits.
grab_window
Specifies the grab window.
keyboard_mode
Specifies further processing of keyboard events.
You can pass GrabModeSync or GrabModeAsync.
owner_events
Specifies a Boolean value that indicates whether
the pointer events are to be reported as usual
or reported with respect to the grab window if
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selected by the event mask.
pointer_mode
Specifies further processing of pointer events.
You can pass GrabModeSync or GrabModeAsync.
time Specifies the time. You can pass either a
timestamp or CurrentTime.
DESCRIPTION
The XGrabPointer function actively grabs control of the
pointer and returns GrabSuccess if the grab was success-
ful. Further pointer events are reported only to the
grabbing client. XGrabPointer overrides any active
pointer grab by this client. If owner_events is False,
all generated pointer events are reported with respect to
grab_window and are reported only if selected by
event_mask. If owner_events is True and if a generated
pointer event would normally be reported to this client,
it is reported as usual. Otherwise, the event is reported
with respect to the grab_window and is reported only if
selected by event_mask. For either value of owner_events,
unreported events are discarded.
If the pointer_mode is GrabModeAsync, pointer event pro-
cessing continues as usual. If the pointer is currently
frozen by this client, the processing of events for the
pointer is resumed. If the pointer_mode is GrabModeSync,
the state of the pointer, as seen by client applications,
appears to freeze, and the X server generates no further
pointer events until the grabbing client calls XAllow-
Events or until the pointer grab is released. Actual
pointer changes are not lost while the pointer is frozen;
they are simply queued in the server for later processing.
If the keyboard_mode is GrabModeAsync, keyboard event pro-
cessing is unaffected by activation of the grab. If the
keyboard_mode is GrabModeSync, the state of the keyboard,
as seen by client applications, appears to freeze, and the
X server generates no further keyboard events until the
grabbing client calls XAllowEvents or until the pointer
grab is released. Actual keyboard changes are not lost
while the pointer is frozen; they are simply queued in the
server for later processing.
If a cursor is specified, it is displayed regardless of
what window the pointer is in. If None is specified, the
normal cursor for that window is displayed when the
pointer is in grab_window or one of its subwindows; other-
wise, the cursor for grab_window is displayed.
If a confine_to window is specified, the pointer is
restricted to stay contained in that window. The con-
fine_to window need have no relationship to the
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grab_window. If the pointer is not initially in the con-
fine_to window, it is warped automatically to the closest
edge just before the grab activates and enter/leave events
are generated as usual. If the confine_to window is sub-
sequently reconfigured, the pointer is warped automati-
cally, as necessary, to keep it contained in the window.
The time argument allows you to avoid certain circum-
stances that come up if applications take a long time to
respond or if there are long network delays. Consider a
situation where you have two applications, both of which
normally grab the pointer when clicked on. If both appli-
cations specify the timestamp from the event, the second
application may wake up faster and successfully grab the
pointer before the first application. The first applica-
tion then will get an indication that the other applica-
tion grabbed the pointer before its request was processed.
XGrabPointer generates EnterNotify and LeaveNotify events.
Either if grab_window or confine_to window is not viewable
or if the confine_to window lies completely outside the
boundaries of the root window, XGrabPointer fails and
returns GrabNotViewable. If the pointer is actively
grabbed by some other client, it fails and returns
AlreadyGrabbed. If the pointer is frozen by an active
grab of another client, it fails and returns GrabFrozen.
If the specified time is earlier than the last-pointer-
grab time or later than the current X server time, it
fails and returns GrabInvalidTime. Otherwise, the last-
pointer-grab time is set to the specified time (Current-
Time is replaced by the current X server time).
XGrabPointer can generate BadCursor, BadValue, and BadWin-
dow errors.
The XUngrabPointer function releases the pointer and any
queued events if this client has actively grabbed the
pointer from XGrabPointer, XGrabButton, or from a normal
button press. XUngrabPointer does not release the pointer
if the specified time is earlier than the last-pointer-
grab time or is later than the current X server time. It
also generates EnterNotify and LeaveNotify events. The X
server performs an UngrabPointer request automatically if
the event window or confine_to window for an active
pointer grab becomes not viewable or if window reconfigu-
ration causes the confine_to window to lie completely out-
side the boundaries of the root window.
The XChangeActivePointerGrab function changes the speci-
fied dynamic parameters if the pointer is actively grabbed
by the client and if the specified time is no earlier than
the last-pointer-grab time and no later than the current X
server time. This function has no effect on the passive
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parameters of a XGrabButton. The interpretation of
event_mask and cursor is the same as described in
XGrabPointer.
XChangeActivePointerGrab can generate a BadCursor and Bad-
Value error.
DIAGNOSTICS
BadCursor A value for a Cursor argument does not name a
defined Cursor.
BadValue Some numeric value falls outside the range of
values accepted by the request. Unless a spe-
cific 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 ALSOXAllowEvents(3X11), XGrabButton(3X11), XGrabKey(3X11),
XGrabKeyboard(3X11)
Xlib - C Language X Interface
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