XGrabPointer(3X11) SDK X11 R4.11MU05 XGrabPointer(3X11)
NAME
XGrabPointer, XUngrabPointer, XChangeActivePointerGrab - grab the
pointer
SYNTAX
int XGrabPointer(display, grabwindow, ownerevents, eventmask,
pointermode,
keyboardmode, confineto, cursor, time)
Display *display;
Window grabwindow;
Bool ownerevents;
unsigned int eventmask;
int pointermode, keyboardmode;
Window confineto;
Cursor cursor;
Time time;
XUngrabPointer(display, time)
Display *display;
Time time;
XChangeActivePointerGrab(display, eventmask, cursor, time)
Display *display;
unsigned int eventmask;
Cursor cursor;
Time time;
ARGUMENTS
confineto
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.
eventmask
Specifies which pointer events are reported to the client.
The mask is the bitwise inclusive OR of the valid pointer
event mask bits.
grabwindow
Specifies the grab window.
keyboardmode
Specifies further processing of keyboard events. You can
pass GrabModeSync or GrabModeAsync.
ownerevents
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.
pointermode
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 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.
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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