XSETDEVICEFOCUS(3) libXi XSETDEVICEFOCUS(3)NAME
XSetDeviceFocus, XGetDeviceFocus - control extension input device focus
SYNTAX
#include <X11/extensions/XInput.h>
XSetDeviceFocus(Display *display, XDevice *device, Window focus,
int revert_to, Time time);
XGetDeviceFocus(Display *display, XDevice *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
notviewable.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 iscalled, 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 requestwill result in a BadMatch error. Whether or not given device can support thisrequest can be determined by the information returned by XOpenDevice. Forthose devices that support focus, XOpenDevice will return an XInputClassInfo
structure with the input_class field equal to the constant FocusClass (definedin the file XI.h).XSetDeviceFocus can generate BadDevice, BadMatch, BadValue, and BadWindow
errors.The XGetDeviceFocus request returns the focus window and the current focusstate.Not all input extension devices can be focused. Attempting to query the focusstate of a device that can't be focused results in a BadMatch error. A devicethat can be focused returns information for input Class Focus when anXOpenDevice 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.
03/04/2009 XSETDEVICEFOCUS(3)