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Table of Contents
XGrabPointer, XUngrabPointer,
XChangeActivePointerGrab - grab the pointer
- int XGrabPointer(Display
*display, Window grab_window,
- Bool owner_events, unsigned int event_mask,
int pointer_mode, int keyboard_mode, Window confine_to, Cursor cursor,
Time time);
- int XUngrabPointer(Display *display, Time time);
- int XChangeActivePointerGrab(Display
*display, unsigned int
- event_mask, Cursor cursor, Time time);
- 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 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.
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 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 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 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.
- 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.
XAllowEvents(3X11)
,
XGrabButton(3X11)
, XGrabKey(3X11)
, XGrabKeyboard(3X11)
Xlib - C Language X Interface
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