XSetDeviceFocus(3X11) X Version 11 (Release 6.1)
XSetDeviceFocus --
control extension input device focus
Synopsis
XSetDeviceFocus(display, device, focus, revert_to, time)
Display *display;
Display *device;
Window focus;
int revert_to;
Time time;
XGetDeviceFocus(display, device, focus_return, revert_to_return, time_return)
Display *display;
Display *device;
Window *focus_return;
int *revert_to_return;
int *time_return;
Arguments
- display
-
Specifies the connection to the X server.
- device
-
Specifies the device whose focus is to be queried or changed.
- focus
-
Specifies the window,
PointerRoot,
FollowKeyboard,
or
None.
- focus_return
-
Returns the focus window,
PointerRoot,
FollowKeyboard,
or
None.
- revert_to
-
Specifies where the input focus reverts to if the window becomes not
viewable.
You can pass
RevertToParent,
RevertToPointerRoot,
RevertToFollowKeyboard,
or
RevertToNone.
- revert_to_return
-
Returns the current focus state
RevertToParent,
RevertToPointerRoot,
RevertToFollowKeyboard,
or
RevertToNone.
- time_return
-
Returns the last_focus_time for the device.
- time
-
Specifies the time.
You can pass either a timestamp or
CurrentTime.
Description
The XSetDeviceFocus
request changes the focus of the specified device and its last-focus-change
time.
It has no effect if the specified time is earlier than the current
last-focus-change time or is later than the current X server time.
Otherwise, the last-focus-change time is set to the specified time
CurrentTime
is replaced by the current X server time).
XSetDeviceFocus
causes the X server to generate
DeviceFocusIn
and
DeviceFocusOut
events.
Depending on the focus argument,
the following occurs:
-
If focus is None ,
all device events are discarded until a new focus window is set,
and the revert_to argument is ignored.
-
If focus is a window, it becomes the device's focus window.
If a generated device event would normally be reported to this window
or one of its inferiors, the event is reported as usual.
Otherwise, the event is reported relative to the focus window.
-
If focus is PointerRoot,
the focus window is dynamically taken to be the root window of whatever screen
the pointer is on at each event from the specified device.
In this case, the revert_to argument is ignored.
-
If focus is FollowKeyboard,
the focus window is dynamically taken to be the window to which the X keyboard
focus is set at each input event.
The specified focus window must be viewable at the time
XSetDeviceFocus
is called,
or a
BadMatch
error results.
If the focus window later becomes not viewable,
the X server
evaluates the revert_to argument to determine the new focus window as follows:
-
If revert_to is RevertToParent,
the focus reverts to the parent (or the closest viewable ancestor),
and the new revert_to value is taken to be
RevertToNone.
-
If revert_to is RevertToPointerRoot,
RevertToFollowKeyboard,
or
RevertToNone,
the focus reverts to
PointerRoot,
FollowKeyboard,
or
None,
respectively.
When the focus reverts,
the X server generates
DeviceFocusIn
and
DeviceFocusOut
events, but the last-focus-change time is not affected.
Input extension devices are not required to support the ability to be focused.
Attempting to set the focus of a device that does not support this request
will result in a BadMatch error. Whether or not given device can
support this request can be determined by the information returned by
XOpenDevice.
For those devices that
support focus, XOpenDevice will return an
XInputClassInfo structure with the input_class
field
equal to the constant FocusClass (defined in the file XI.h).
XSetDeviceFocus
can generate
BadDevice,
BadMatch,
BadValue,
and
BadWindow
errors.
The
XGetDeviceFocus
request returns the focus window and the current focus state.
Not all input extension devices can be focused. Attempting to query the
focus state of a device that can't be focused results in a BadMatch
error. A device that can be focused returns information for input Class
Focus when an XOpenDevice request is made.
XGetDeviceFocus can generate BadDevice,
and BadMatch errors.
Diagnostics
- BadDevice
-
An invalid device was specified. The specified device does not exist or has
not been opened by this client via XOpenInputDevice. This error may
also occur if the specified device is the X keyboard or X pointer device.
- 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.
- BadMatch
-
This error may occur if an XGetDeviceFocus or XSetDeviceFocus
request was made specifying a device that the server implementation does not
allow to be focused.
References
Xlib - C Language X Interface
UnixWare 7 BL14 Release -- October 1997
© 1997 The Santa Cruz Operation, Inc. All rights reserved.