XGrabPointer(3X11) X Version 11 (Release 4) 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
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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
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 successful.
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
processing continues as usual. If the pointer is currently
frozen by this client, the processing of events for the
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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 XAllowEvents
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
processing 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; otherwise, 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 confine_to
window need have no relationship to the grab_window. If the
pointer is not initially in the confine_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 subsequently
reconfigured, the pointer is warped automatically, as
necessary, to keep it contained in the window.
The time argument allows you to avoid certain circumstances
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 applications specify
the timestamp from the event, the second application may
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wake up faster and successfully grab the pointer before the
first application. The first application then will get an
indication that the other application 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 (CurrentTime is replaced by the
current X server time).
XGrabPointer can generate BadCursor, BadValue, and BadWindow
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 reconfiguration causes the
confine_to window to lie completely outside the boundaries
of the root window.
The XChangeActivePointerGrab function changes the specified
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
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server time. This function has no effect on the passive
parameters of a XGrabButton. The interpretation of
event_mask and cursor is the same as described in
XGrabPointer.
XChangeActivePointerGrab can generate a BadCursor and
BadValue 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 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
XAllowEvents(3X11), XGrabButton(3X11), XGrabKey(3X11),
XGrabKeyboard(3X11)
Xlib - C Language X Interface
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