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XGetDeviceFocus

NAME

XSetDeviceFocus, XGetDeviceFocus - control extension input device focus

SYNOPSIS

 #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 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.