NAME
XGrabPointer, XUngrabPointer, XChangeActivePointerGrab - grab the pointer
SYNTAX
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);
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 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 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(3), XGrabButton(3), XGrabKey(3), XGrabKeyboard(3)
Xlib - C Language X Interface