xref: /xsrc/external/mit/libXi/dist/specs/library.xml

<chapter><title>Input Extension</title>
<sect1 id='Overview'>
<title>Overview</title>
<!-- .XS -->
<!-- (SN Input Extension Overview -->
<!-- .XE -->
<para>
<!-- .LP -->
This document describes an extension to
the X11 server.  The purpose of this extension is to support the use
of additional input devices beyond the pointer and keyboard devices
defined by the core X protocol.  This first section gives an overview
of the input extension.  The following sections correspond to 
chapters 9, 10, and 11, ``Window and Session Manager Functions'',
``Events'', and ``Event Handling Functions'' of the
``Xlib - C Language Interface'' manual
and describe how to use the input device extension.
</para>
<sect2 id="Design_Approach">
<title>Design Approach</title>
<!-- .XS -->
<!-- (SN Design Approach -->
<!-- .XE -->
<para>
<!-- .LP -->
The design approach of the extension is to define functions
and events analogous to the core functions and events.
This allows extension input devices and events to be individually
distinguishable from each other and from the core input devices and events.
These functions and events make use of a device identifier and support the
reporting of <emphasis remap='I'>n</emphasis>-dimensional motion data as well as other data that
is not currently reportable via the core input events.
</para>
</sect2>
<sect2 id="Core_Input_Devices">
<title>Core Input Devices</title>
<!-- .XS -->
<!-- (SN Core Input Devices -->
<!-- .XE -->
<para>
<!-- .LP -->
The X server core protocol supports two input devices:  a pointer and a
keyboard.  The pointer device has two major functions. 
First, it may be used to generate motion information
that client programs can detect. Second, it may also be used to indicate the
current location and focus of the X keyboard.  To accomplish this, the server 
echoes a cursor at the current position of the X pointer.  Unless the X
keyboard has been explicitly focused, this cursor also shows the current
location and focus of the X keyboard.
</para>
<para>
<!-- .LP -->
The X keyboard is used to generate input that client programs can detect.
</para>
<para>
<!-- .LP -->
The X keyboard and X pointer are referred to in this document as 
the <emphasis remap='I'>core devices</emphasis>, and the input
events they generate 
<function>( KeyPress ,</function>
<function>KeyRelease ,</function>
<function>ButtonPress ,</function>
<function>ButtonRelease ,</function>
and
<function>MotionNotify )</function>
are known as the <emphasis remap='I'>core input events</emphasis>.  All other
input devices are referred to as <emphasis remap='I'>extension input devices</emphasis>, and the 
input events they generate are referred to as <emphasis remap='I'>extension input events</emphasis>.
<!-- .NT -->
This input extension does not change the behavior or functionality of the
core input devices, core events, or core protocol requests, with the
exception of the core grab requests.  These requests may affect the
synchronization of events from extension devices.  See the explanation
in the section titled ``Event Synchronization and Core Grabs.''
<!-- .NE -->
</para>
<para>
<!-- .LP -->
Selection of the physical devices to be initially used by the server as the 
core devices is left implementation dependent.  Functions are defined that
allow client programs to change which physical devices are used as the
core devices.
</para>
</sect2>
<sect2 id="Extension_Input_Devices">
<title>Extension Input Devices</title>
<!-- .XS -->
<!-- (SN Extension Input Devices -->
<!-- .XE -->
<para>
<!-- .LP -->
The input extension controls access to input devices other than the X keyboard
and X pointer.  It allows client programs to select input from these devices 
independently
from each other and independently from the core devices.  Input events from
these devices are of extension types 
<function>( DeviceKeyPress ,</function>
<function>DeviceKeyRelease ,</function>
<function>DeviceButtonPress ,</function>
<function>DeviceButtonRelease ,</function>
<function>DeviceMotionNotify ,</function>
and so on) and contain
a device identifier so that events of the same type coming from different
input devices can be distinguished.
</para>
<para>
<!-- .LP -->
Extension input events are not limited in size by the size of the server
32-byte wire events.  Extension input events
may be constructed by the server sending as many
wire-sized events as necessary to return the information required for
that event.
The library event reformatting routines
are responsible for combining these into one or more client XEvents.
</para>
<para>
<!-- .LP -->
Any input device that generates key, button, or motion data may be used as
an extension input device.
Extension input devices may have zero or more keys, zero or more buttons,
and may report zero or more axes of motion.  Motion may be reported 
as relative movements from a previous position or as an absolute
position.  All valuators reporting motion information for a given
extension input device must report the same kind of motion information
(absolute or relative).
</para>
<para>
<!-- .LP -->
This extension is designed to accommodate new types of input devices that
may be added in the future.  The protocol requests that refer to
specific characteristics of input devices organize that information
by <emphasis remap='I'>input device classes</emphasis>.  Server implementors may add new
classes of input devices without changing the protocol requests.
</para>
<para>
<!-- .LP -->
All extension input
devices are treated like the core X keyboard in determining their location
and focus.  The server does not track the location of these devices on an
individual basis and, therefore,
does not echo a cursor to indicate their current location.
Instead, their location is determined by the location of the core X pointer.
Like the core X keyboard, some may be explicitly focused. If they are
not explicitly focused,  their focus
is determined by the location of the core X pointer.
</para>
<sect3 id="Input_Device_Classes">
<title>Input Device Classes</title>
<!-- .XS -->
<!-- (SN Input Device Classes -->
<!-- .XE -->
<para>
<!-- .LP -->
Some of the input extension requests divide input devices into classes
based on their functionality.  This is intended to allow new classes of input
devices to be defined at a later time without changing the semantics of 
these functions.  The following input device classes are currently
defined:
<variablelist>
  <varlistentry>
    <term>KEY</term>
    <listitem>
      <para>
The device reports key events.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>BUTTON</term>
    <listitem>
      <para>
The device reports button events.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>VALUATOR</term>
    <listitem>
      <para>
The device reports valuator data in motion events.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>PROXIMITY</term>
    <listitem>
      <para>
The device reports proximity events.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>FOCUS</term>
    <listitem>
      <para>
The device can be focused.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>FEEDBACK</term>
    <listitem>
      <para>
The device supports feedbacks.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
Additional classes may be added in the future.
Functions that support multiple input classes, such as the 
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
function that lists all available input devices,
organize the data they return by input class.  Client programs that
use these functions should not access data unless it matches a 
class defined at the time those clients were compiled.  In this way,
new classes can be added without forcing existing clients that use
these functions to be recompiled.
</para>
</sect3>
</sect2>
<sect2 id="Using_Extension_Input_Devices">
<title>Using Extension Input Devices</title>
<!-- .XS -->
<!-- (SN Using Extension Input Devices -->
<!-- .XE -->
<para>
<!-- .LP -->
A client that wishes to access an input device does so through the library
functions defined in the following sections.  A typical sequence of requests
that a client would make is as follows:
</para>
<itemizedlist>
  <listitem>
    <para>
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
- lists all of the available input devices.  From the 
information returned by this request, determine whether the desired input
device is attached to the server.  For a description of the 
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request, see the section entitled ``Listing Available Devices.''
    </para>
  </listitem>
  <listitem>
    <para>
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
- requests that the server open the device for access by this client.
This request returns an 
<function>XDevice</function>
structure that is used
by most other input extension requests to identify the specified device.
For a description of the 
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
request, see the section entitled ``Enabling and Disabling Extension Devices.''
    </para>
  </listitem>
  <listitem>
    <para>
Determine the event types and event classes needed to select the desired
input extension events, and identify them when they are received.
This is done via macros whose name corresponds to the desired event, for
example,
<function>DeviceKeyPress .</function>
For a description of these macros,
see the section entitled ``Selecting Extension Device Events.''
    </para>
  </listitem>
  <listitem>
    <para>
<xref linkend='XSelectExtensionEvent' xrefstyle='select: title'/>
- selects the desired events from the server.
For a description of the 
<function>XSelextExtensionEvent</function>
request, see the section entitled ``Selecting Extension Device Events.''
    </para>
  </listitem>
  <listitem>
    <para>
<olink targetdoc='libX11' targetptr='XNextEvent'><function>XNextEvent</function></olink>
- receives the next available event.  This is the core
<olink targetdoc='libX11' targetptr='XNextEvent'><function>XNextEvent</function></olink>
function provided by the standard X library.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
Other requests are defined to grab and focus extension devices, to
change their key, button, or modifier mappings, to control the
propagation of input extension events, to get motion history from an
extension device, and to send input extension events to another client.
These functions are described in the following sections.
</para>
</sect2>
</sect1>
<sect1 id="Library_Extension_Requests">
<title>Library Extension Requests</title>
<!-- .XS -->
<!-- (SN Library Extension Requests -->
<!-- .XE -->
<para>
<!-- .LP -->
Extension input devices are accessed by client programs through the 
use of new protocol requests.
The following requests are provided as extensions to Xlib.  Constants
and structures referenced by these functions may be found in the 
files <function>&lt;X11/extensions/XI.h&gt;</function> and <function>&lt;X11/extensions/XInput.h&gt;</function>,
which are attached to this document as 
Appendix A.<!-- xref -->
</para>
<para>
<!-- .LP -->
The library will return <function>NoSuchExtension</function> if an extension request
is made to a server that does not support the input extension.
</para>
<para>
<!-- .LP -->
Input extension requests cannot be used to access the X keyboard and
X pointer devices.
</para>
<sect2 id="Window_Manager_Functions">
<title>Window Manager Functions</title>
<!-- .XS -->
<!-- (SN Window Manager Functions -->
<!-- .XE -->
<para>
<!-- .LP -->
This section discusses the following X Input Extension Window Manager topics:
</para>
<itemizedlist>
  <listitem>
    <para>
Changing the core devices
    </para>
  </listitem>
  <listitem>
    <para>
Event synchronization and core grabs
    </para>
  </listitem>
  <listitem>
    <para>
Extension active grabs
    </para>
  </listitem>
  <listitem>
    <para>
Passively grabbing a key
    </para>
  </listitem>
  <listitem>
    <para>
Passively grabbing a button
    </para>
  </listitem>
  <listitem>
    <para>
Thawing a device
    </para>
  </listitem>
  <listitem>
    <para>
Controlling device focus
    </para>
  </listitem>
  <listitem>
    <para>
Controlling device feedback
    </para>
  </listitem>
  <listitem>
    <para>
Ringing a bell on an input device
    </para>
  </listitem>
  <listitem>
    <para>
Controlling device encoding
    </para>
  </listitem>
  <listitem>
    <para>
Controlling button mapping
    </para>
  </listitem>
  <listitem>
    <para>
Obtaining the state of a device
    </para>
  </listitem>
</itemizedlist>
<sect3 id="Changing_the_Core_Devices">
<title>Changing the Core Devices</title>
<!-- .XS -->
<!-- (SN Changing the Core Devices -->
<!-- .XE -->

<para>
<!-- .LP -->
These functions are provided to change which physical device is used
as the X pointer or X keyboard.
</para>
<!-- .NT -->
<note><para>
Using these functions may change the characteristics of the core devices.
The new pointer device may have a different number of buttons from the 
old one, or the new keyboard device may have a different number of
keys or report a different range of keycodes.  Client programs may be
running that depend on those characteristics.  For example, a client
program could allocate an array based on the number of buttons on the
pointer device and then use the button numbers received in button events
as indices into that array.  Changing the core devices could cause
such client programs to behave improperly or to terminate abnormally
if they ignore the 
<function>ChangeDeviceNotify</function>
event generated by these requests.
</para></note>
<!-- .NE -->

<para>
<!-- .LP -->
These functions change the X keyboard or X pointer device and generate an
<function>XChangeDeviceNotify</function>
event and a
<function>MappingNotify</function>
event.  
The specified device becomes the
new X keyboard or X pointer device.  The location of the core device
does not change as a result of this request.
</para>
<para>
<!-- .LP -->
These requests fail and return 
<function>AlreadyGrabbed</function>
if either the specified
device or the core device it would replace are grabbed by some other client.
They fail and return 
<function>GrabFrozen</function>
if either device is frozen by the active grab of another client.
</para>
<para>
<!-- .LP -->
These requests fail with a
<function>BadDevice</function>
error if the specified device is invalid, has not previously been opened via
<function>XOpenDevice ,</function>
or is
not supported as a core device by the server implementation.
</para>
<para>
<!-- .LP -->
Once the device has successfully replaced one of the core devices, it
is treated as a core device until it is in turn replaced by another
<function>ChangeDevice</function>
request or until the server terminates.  The termination
of the client that changed the device will not cause it to change back.
Attempts to use the
<xref linkend='XCloseDevice' xrefstyle='select: title'/>
request to close the new core device will fail with a
<function>BadDevice</function>
error.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To change which physical device is used as the X keyboard, use the 
<xref linkend='XChangeKeyboardDevice' xrefstyle='select: title'/>
function.
The specified device must support input class 
<function>Keys</function>
(as reported in the
<function>ListInputDevices</function>
request) or the request will fail with a 
<function>BadMatch</function>
error.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XChangeKeyboardDevice'>
<funcprototype>
  <funcdef>int <function> XChangeKeyboardDevice</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
If no error occurs, 
<xref linkend='XChangeKeyboardDevice' xrefstyle='select: title'/>
returns 
<function>Success .</function>
A 
<function>ChangeDeviceNotify</function>
event with the request field set to 
<function>NewKeyboard</function>
is sent to all clients selecting that event.
A 
<function>MappingNotify</function>
event with the request field set to
<function>MappingKeyboard</function>
is sent to all clients.
The requested device becomes the X keyboard, and the old keyboard becomes 
available as an extension input device.
The focus state of the new keyboard is the same as
the focus state of the old X keyboard.
</para>
<para>
<!-- .LP -->
<xref linkend='XChangeKeyboardDevice' xrefstyle='select: title'/>
can generate
<function>AlreadyGrabbed ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
and 
<function>GrabFrozen</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To change which physical device is used as the X pointer,
use the
<xref linkend='XChangePointerDevice' xrefstyle='select: title'/>
function.
The specified device must support input class 
<function>Valuators</function>
(as reported in the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request) and report at least two axes of motion,
or the request will fail with a 
<function>BadMatch</function>
error.
If the specified device reports more than two axes, the two specified in
the xaxis and yaxis arguments will be used.  Data from other
valuators on the device will be ignored.
</para>
<para>
<!-- .LP -->
If the specified device reports absolute positional information, and the 
server implementation does not allow such a device to be used as the 
X pointer, the request will fail with a 
<function>BadDevice</function>
error.
<!-- .sM -->
<funcsynopsis id='XChangePointerDevice'>
<funcprototype>
  <funcdef>int <function> XChangePointerDevice</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> xaxis</parameter></paramdef>
  <paramdef>int<parameter> yaxis</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>xaxis</emphasis>
    </term>
    <listitem>
      <para>
Specifies the zero-based index of the axis to be used as the x-axis of the 
pointer device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>yaxis</emphasis>
    </term>
    <listitem>
      <para>
Specifies the zero-based index of the axis to be used as the y-axis of the 
pointer device.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
If no error occurs, 
<xref linkend='XChangePointerDevice' xrefstyle='select: title'/>
returns 
<function>Success .</function>
A 
<function>ChangeDeviceNotify</function>
event with the request field set to 
<function>NewPointer</function>
is sent to all clients selecting that event.
A
<function>MappingNotify</function>
event with the request field set to
<function>MappingPointer</function>
is sent to all clients.
The requested device becomes the X pointer, and the old pointer becomes 
available as an extension input device.
</para>
<para>
<!-- .LP -->
<xref linkend='XChangePointerDevice' xrefstyle='select: title'/>
can generate
<function>AlreadyGrabbed ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
and 
<function>GrabFrozen</function>
errors.
</para>
</sect3>
<sect3 id="Event_Synchronization_and_Core_Grabs">
<title>Event Synchronization and Core Grabs</title>
<!-- .XS -->
<!-- (SN Event Synchronization and Core Grabs -->
<!-- .XE -->
<para>
<!-- .LP -->
Implementation of the input extension requires an extension of the
meaning of event synchronization for the core grab requests.  This is
necessary in order to allow window managers to freeze all input devices
with a single request.
</para>
<para>
<!-- .LP -->
The core grab requests require a pointer_mode and keyboard_mode
argument.  The meaning of these modes is changed by the input extension.
For the
<olink targetdoc='libX11' targetptr='XGrabPointer'><function>XGrabPointer</function></olink>
and 
<olink targetdoc='libX11' targetptr='XGrabButton'><function>XGrabButton</function></olink>
requests, pointer_mode controls synchronization of the pointer device, 
and keyboard_mode controls the synchronization of all other input devices.  
For the 
<olink targetdoc='libX11' targetptr='XGrabKeyboard'><function>XGrabKeyboard</function></olink>
and
<olink targetdoc='libX11' targetptr='XGrabKey'><function>XGrabKey</function></olink>
requests, pointer_mode controls the synchronization
of all input devices, except the X keyboard, while keyboard_mode controls
the synchronization of the keyboard.  When using one of the core grab
requests, the synchronization of extension devices
is controlled by the mode specified for the device not being grabbed.
</para>
</sect3>
<sect3 id="Extension_Active_Grabs">
<title>Extension Active Grabs</title>
<!-- .XS -->
<!-- (SN Extension Active Grabs -->
<!-- .XE -->
<para>
<!-- .LP -->
Active grabs of
extension devices are supported via the 
<xref linkend='XGrabDevice' xrefstyle='select: title'/>
function in the same way that core devices are grabbed using the core 
<olink targetdoc='libX11' targetptr='XGrabKeyboard'><function>XGrabKeyboard</function></olink>
function, except that an extension input device
is passed as a function parameter.  
The 
<xref linkend='XUngrabDevice' xrefstyle='select: title'/>
function allows a previous active grab for an extension device to be released.
</para>
<para>
<!-- .LP -->
Passive grabs of buttons and keys on extension devices are supported
via the 
<xref linkend='XGrabDeviceButton' xrefstyle='select: title'/>
and 
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
functions.
These passive grabs are released via the
<xref linkend='XUngrabDeviceKey' xrefstyle='select: title'/>
and
<xref linkend='XUngrabDeviceButton' xrefstyle='select: title'/>
functions.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To grab an extension device, use the
<xref linkend='XGrabDevice' xrefstyle='select: title'/>
function.
The device must have previously been opened using the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function.
<!-- .sM -->
<funcsynopsis id='XGrabDevice'>
<funcprototype>
  <funcdef>int <function> XGrabDevice</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>Window<parameter> grab_window</parameter></paramdef>
  <paramdef>Bool<parameter> owner_events</parameter></paramdef>
  <paramdef>int<parameter> event_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> *event_list</parameter></paramdef>
  <paramdef>int<parameter> this_device_mode</parameter></paramdef>
  <paramdef>int<parameter> other_device_mode</parameter></paramdef>
  <paramdef>Time<parameter> time</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      "<emphasis remap='I'>display</emphasis>"
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>grab_window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of a window associated with the device specified above.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>owner_events</emphasis>
    </term>
    <listitem>
      <para>
Specifies a boolean value of either 
<function>True</function>
or 
<function>False .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of elements in the event_list array.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_list</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to a list of event classes that indicate which events
the client wishes to receive.  
These event classes must have been obtained
using the device being grabbed.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>this_device_mode</emphasis>
    </term>
    <listitem>
      <para>
Controls further processing of events from this device.  You can pass one
of these constants: 
<function>GrabModeSync</function>
or 
<function>GrabModeAsync .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>other_device_mode</emphasis>
    </term>
    <listitem>
      <para>
Controls further processing of events from all other devices.  You can pass one
of these constants:
<function>GrabModeSync</function>
or 
<function>GrabModeAsync .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>time</emphasis>
    </term>
    <listitem>
      <para>
Specifies the time.  This may be either a timestamp expressed in
milliseconds or
<function>CurrentTime .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGrabDevice' xrefstyle='select: title'/>
actively grabs an extension input device and generates 
<function>DeviceFocusIn</function>
and 
<function>DeviceFocusOut</function>
events.
Further input events from this device are reported only to the grabbing client.
This function overrides any previous active grab by this client for this device.
</para>
<para>
<!-- .LP -->
The event_list parameter is a pointer to a list of event classes.  This list
indicates which events the client wishes to receive while the grab is active.
If owner_events is 
<function>False ,</function>
input events from this device are reported with respect to 
grab_window and are reported only if specified in event_list.
If owner_events is
<function>True ,</function>
then if a generated event would normally be reported to this client,
it is reported normally.
Otherwise, the event is reported with respect to the grab_window and is only
reported if specified in event_list.
</para>
<para>
<!-- .LP -->
The this_device_mode argument controls the further processing 
of events from this device, and the other_device_mode argument controls
the further processing of input events from all other devices.
</para>
<itemizedlist>
  <listitem>
    <para>
If the this_device_mode argument is 
<function>GrabModeAsync ,</function>
device event processing continues
normally; if the device is currently frozen by this client, then
processing of device events is resumed.
If the this_device_mode  argument is
<function>GrabModeSync ,</function>
the state of the grabbed device
(as seen by client applications) appears to freeze,
and no further device events are generated by the server until the
grabbing client issues a releasing 
<xref linkend='XAllowDeviceEvents' xrefstyle='select: title'/>
call or until the device grab is released.
Actual device input events are not lost while the device is frozen; they are
simply queued for later processing.
    </para>
  </listitem>
  <listitem>
    <para>
If the other_device_mode is 
<function>GrabModeAsync ,</function>
event processing from other input devices is unaffected
by activation of the grab.  
If other_device_mode is 
<function>GrabModeSync ,</function>
the state of all devices except the grabbed device
(as seen by client applications) appears to freeze, and no further
events are generated by the server until the grabbing client issues a
releasing 
<olink targetdoc='libX11' targetptr='XAllowEvents'><function>XAllowEvents</function></olink>
or 
<xref linkend='XAllowDeviceEvents' xrefstyle='select: title'/>
call or until the device grab is released.
Actual events are not lost
while the other devices are frozen; they are simply queued for later
processing.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
<xref linkend='XGrabDevice' xrefstyle='select: title'/>
fails on the following conditions:
</para>
<itemizedlist>
  <listitem>
    <para>
If the device is actively grabbed by some other client, it returns
<function>AlreadyGrabbed .</function>
    </para>
  </listitem>
  <listitem>
    <para>
If grab_window is not viewable, it returns
<function>GrabNotViewable .</function>
    </para>
  </listitem>
  <listitem>
    <para>
If the specified time is earlier
than the last-grab-time for the specified device
or later than the current X server time, it returns
<function>GrabInvalidTime .</function>
Otherwise,
the last-grab-time for the specified device is set
to the specified time and 
<function>CurrentTime</function>
is replaced by the current X server time.
    </para>
  </listitem>
  <listitem>
    <para>
If the device is frozen by an active grab of another client, it returns
<function>GrabFrozen .</function>
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
If a grabbed device is closed by a client while an active grab by that 
client is in effect, that active grab will be released. 
Any passive grabs established by that client will be released.
If the device is frozen only by an active grab
of the requesting client, it is thawed.
</para>
<para>
<!-- .LP -->
<xref linkend='XGrabDevice' xrefstyle='select: title'/>
can generate
<function>BadClass ,</function>
<function>BadDevice ,</function>
<function>BadValue ,</function>
and
<function>BadWindow</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To release a grab of an extension device, use the
<xref linkend='XUngrabDevice' xrefstyle='select: title'/>
function.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XUngrabDevice'>
<funcprototype>
  <funcdef>int <function> XUngrabDevice</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>Time<parameter> time</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>time</emphasis>
    </term>
    <listitem>
      <para>
Specifies the time.  This may be either a timestamp expressed in
milliseconds, or 
<function>CurrentTime .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XUngrabDevice' xrefstyle='select: title'/>
allows a client to release an extension input device and any
queued events if this client has it grabbed from either
<xref linkend='XGrabDevice' xrefstyle='select: title'/>
or
<function>XGrabDeviceKey .</function>
If any other devices are frozen by the grab,
<xref linkend='XUngrabDevice' xrefstyle='select: title'/>
thaws them. 
This function does not release the device and any
queued events if the specified time is earlier than the last-device-grab
time or is later than the current X server time.  It also generates 
<function>DeviceFocusIn</function>
and 
<function>DeviceFocusOut</function>
events.  The X server automatically performs an
<xref linkend='XUngrabDevice' xrefstyle='select: title'/>
if the event window for an active device grab becomes not viewable
or if the client terminates without releasing the grab.
</para>
<para>
<!-- .LP -->
<xref linkend='XUngrabDevice' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
errors.
</para>
</sect3>
<sect3 id="Passively_Grabbing_a_Key">
<title>Passively Grabbing a Key</title>
<!-- .XS -->
<!-- (SN Passively Grabbing a Key -->
<!-- .XE -->
<para>
<!-- .LP -->
To passively grab a single key on an extension device, use
<function>XGrabDeviceKey .</function>
That device must have previously been opened using the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function, or the request will fail with a
<function>BadDevice</function>
error.  
If the specified device does not support input class
<function>Keys ,</function>
the request will fail with a
<function>BadMatch</function>
error.
<!-- .sM -->
<funcsynopsis id='XGrabDeviceKey'>
<funcprototype>
  <funcdef>int <function> XGrabDeviceKey</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> keycode</parameter></paramdef>
  <paramdef>unsignedint<parameter> modifiers</parameter></paramdef>
  <paramdef>XDevice<parameter> *modifier_device</parameter></paramdef>
  <paramdef>Window<parameter> grab_window</parameter></paramdef>
  <paramdef>Bool<parameter> owner_events</parameter></paramdef>
  <paramdef>int<parameter> event_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> *event_list</parameter></paramdef>
  <paramdef>int<parameter> this_device_mode</parameter></paramdef>
  <paramdef>int<parameter> other_device_mode</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>keycode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the keycode of the key that is to be grabbed.  You can pass
either the keycode or 
<function>AnyKey .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifiers</emphasis>
    </term>
    <listitem>
      <para>
Specifies the set of keymasks.  This mask is the bitwise inclusive OR
of these keymask bits:  
<function>ShiftMask ,</function>
<function>LockMask ,</function>
<function>ControlMask ,</function>
<function>Mod1Mask ,</function>
<function>Mod2Mask ,</function>
<function>Mod3Mask ,</function>
<function>Mod4Mask ,</function>
and
<function>Mod5Mask .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      
    </term>
    <listitem>
      <para>
You can also pass 
<function>AnyModifier ,</function>
which is equivalent to issuing the grab key request 
for all possible modifier combinations (including the combination
of no modifiers).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifier_device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose modifiers are to be used.  If NULL is 
specified, the core X keyboard is used as the modifier_device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>grab_window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of a window associated with the device specified above.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>owner_events</emphasis>
    </term>
    <listitem>
      <para>
Specifies a boolean value of either
<function>True</function>
or
<function>False .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of elements in the event_list array.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_list</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to a list of event classes that indicate which events
the client wishes to receive.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>this_device_mode</emphasis>
    </term>
    <listitem>
      <para>
Controls further processing of events from this device.
You can pass one of these constants:
<function>GrabModeSync</function>
or
<function>GrabModeAsync .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>other_device_mode</emphasis>
    </term>
    <listitem>
      <para>
Controls further processing of events from all other devices.
You can pass one of these constants: 
<function>GrabModeSync</function>
or
<function>GrabModeAsync .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
is analogous to the core 
<olink targetdoc='libX11' targetptr='XGrabKey'><function>XGrabKey</function></olink>
function.  It creates an
explicit passive grab for a key on an extension device.
The 
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
function establishes a passive grab on a device.
Consequently, in the future, 
</para>
<itemizedlist>
  <listitem>
    <para>
IF the device is not grabbed and the specified key, 
which itself can be a modifier key, is logically pressed
when the specified modifier keys logically are down on the specified
modifier device (and no other keys are down),
    </para>
  </listitem>
  <listitem>
    <para>
AND no other modifier keys logically are down,
    </para>
  </listitem>
  <listitem>
    <para>
AND EITHER the grab window is an ancestor of (or is) the focus window
or the grab window is a descendent of the focus window and contains the pointer,
    </para>
  </listitem>
  <listitem>
    <para>
AND a passive grab on the same device and key combination does not exist on any
ancestor of the grab window,
    </para>
  </listitem>
  <listitem>
    <para>
THEN the device is actively grabbed, as for
<function>XGrabDevice ,</function>
the last-device-grab time is set to the time at which the key was pressed
(as transmitted in the 
<function>DeviceKeyPress</function>
event), and the 
<function>DeviceKeyPress</function>
event is reported.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
The interpretation of the remaining arguments is as for
<function>XGrabDevice .</function>
The active grab is terminated automatically when the logical state of the
device has the specified key released
(independent of the logical state of the modifier keys).
</para>
<para>
<!-- .LP -->
Note that the logical state of a device (as seen by means of the X protocol)
may lag the physical state if device event processing is frozen.
</para>
<para>
<!-- .LP -->
A modifier of 
<function>AnyModifier</function>
is equivalent to issuing the request for all
possible modifier combinations (including the combination of no modifiers).  
It is not required that all modifiers specified have
currently assigned keycodes.
A key of 
<function>AnyKey</function>
is equivalent to issuing
the request for all possible keycodes.  Otherwise, the key must be in
the range specified by min_keycode and max_keycode in the 
information returned by the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
function.
If it is not within that range, 
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
generates a
<function>BadValue</function>
error.
</para>
<para>
<!-- .LP -->
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
generates a
<function>BadAccess</function>
error if some other client has issued a 
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
with the same device and key combination on the same window.
When using
<function>AnyModifier</function>
or
<function>AnyKey ,</function>
the request fails completely and the X server generates a
<function>BadAccess</function>
error, and no grabs are established if there is a conflicting grab
for any combination.
</para>
<para>
<!-- .LP -->
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
returns
<function>Success</function>
upon successful completion of the request.
</para>
<para>
<!-- .LP -->
<xref linkend='XGrabDeviceKey' xrefstyle='select: title'/>
can generate
<function>BadAccess ,</function>
<function>BadClass ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
<function>BadValue ,</function>
and
<function>BadWindow</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To release a passive grab of a single key on an extension device, use
<function>XUngrabDeviceKey .</function>
<!-- .sM -->
<funcsynopsis id='XUngrabDeviceKey'>
<funcprototype>
  <funcdef>int <function> XUngrabDeviceKey</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> keycode</parameter></paramdef>
  <paramdef>unsignedint<parameter> modifiers</parameter></paramdef>
  <paramdef>XDevice<parameter> *modifier_device</parameter></paramdef>
  <paramdef>Window<parameter> ungrab_window</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>keycode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the keycode of the key that is to be ungrabbed.  You can pass
either the keycode or
<function>AnyKey .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifiers</emphasis>
    </term>
    <listitem>
      <para>
Specifies the set of keymasks.  This mask is the bitwise inclusive OR
of these keymask bits:
<function>ShiftMask ,</function>
<function>LockMask ,</function>
<function>ControlMask , </function>
<function>Mod1Mask ,</function>
<function>Mod2Mask ,</function>
<function>Mod3Mask ,</function>
<function>Mod4Mask ,</function>
and
<function>Mod5Mask .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      
    </term>
    <listitem>
      <para>
You can also pass
<function>AnyModifier ,</function>
which is equivalent to issuing the ungrab key 
request for all possible modifier combinations (including the combination
of no modifiers).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifier_device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose modifiers are to be used.  If NULL is 
specified, the core X keyboard is used as the modifier_device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>ungrab_window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of a window associated with the device specified above.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XUngrabDeviceKey' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XUngrabKey'><function>XUngrabKey</function></olink>
function.  It releases an explicit passive grab for a key 
on an extension input device.
</para>
<para>
<!-- .LP -->
<xref linkend='XUngrabDeviceKey' xrefstyle='select: title'/>
can generate
<function>BadAlloc ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
<function>BadValue ,</function>
and 
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Passively_Grabbing_a_Button">
<title>Passively Grabbing a Button</title>
<!-- .XS -->
<!-- (SN Passively Grabbing a Button -->
<!-- .XE -->
<para>
<!-- .LP -->
To establish a passive grab for a single button on an extension device, use
<function>XGrabDeviceButton .</function>
The specified device must have previously been opened using the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function, or the request will fail with a 
<function>BadDevice</function>
error.  If the specified device does not support input class
<function>Buttons ,</function>
the request will fail with a 
<function>BadMatch</function>
error.
<!-- .sM -->
<funcsynopsis id='XGrabDeviceButton'>
<funcprototype>
  <funcdef>int <function> XGrabDeviceButton</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>unsignedint<parameter> button</parameter></paramdef>
  <paramdef>unsignedint<parameter> modifiers</parameter></paramdef>
  <paramdef>XDevice*modifier_device<parameter> </parameter></paramdef>
  <paramdef>Window<parameter> grab_window</parameter></paramdef>
  <paramdef>Bool<parameter> owner_events</parameter></paramdef>
  <paramdef>int<parameter> event_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> *event_list</parameter></paramdef>
  <paramdef>int<parameter> this_device_mode</parameter></paramdef>
  <paramdef>int<parameter> other_device_mode</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>button</emphasis>
    </term>
    <listitem>
      <para>
Specifies the code of the button that is to be grabbed.  You can pass
either the button or
<function>AnyButton .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifiers</emphasis>
    </term>
    <listitem>
      <para>
Specifies the set of keymasks.  This mask is the bitwise inclusive OR
of these keymask bits:
<function>ShiftMask ,</function>
<function>LockMask ,</function>
<function>ControlMask , </function>
<function>Mod1Mask ,</function>
<function>Mod2Mask ,</function>
<function>Mod3Mask ,</function>
<function>Mod4Mask ,</function>
and
<function>Mod5Mask .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      
    </term>
    <listitem>
      <para>
You can also pass 
<function>AnyModifier ,</function>
which is equivalent to issuing the grab request 
for all possible modifier combinations (including the combination
of no modifiers).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifier_device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose modifiers are to be used.  If NULL is 
specified, the core X keyboard is used as the modifier_device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>grab_window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of a window associated with the device specified above.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>owner_events</emphasis>
    </term>
    <listitem>
      <para>
Specifies a boolean value of either
<function>True</function>
or
<function>False .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of elements in the event_list array.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_list</emphasis>
    </term>
    <listitem>
      <para>
Specifies a list of event classes that indicates which device events are to be 
reported to the client.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>this_device_mode</emphasis>
    </term>
    <listitem>
      <para>
Controls further processing of events from this device.  You can pass one
of these constants:
<function>GrabModeSync</function>
or
<function>GrabModeAsync .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>other_device_mode</emphasis>
    </term>
    <listitem>
      <para>
Controls further processing of events from all other devices.  You can pass one
of these constants:
<function>GrabModeSync</function>
or
<function>GrabModeAsync .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGrabDeviceButton' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XGrabButton'><function>XGrabButton</function></olink>
function.  
It creates an explicit passive grab for a button on an extension input device.
Because the server does not track extension devices,
no cursor is specified with this request.
For the same reason, there is no confine_to parameter.
The device must have previously been opened using the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function.
</para>
<para>
<!-- .LP -->
The
<xref linkend='XGrabDeviceButton' xrefstyle='select: title'/>
function establishes a passive grab on a device.
Consequently, in the future, 
</para>
<itemizedlist>
  <listitem>
    <para>
IF the device is not grabbed and the specified button is logically pressed
when the specified modifier keys logically are down 
(and no other buttons or modifier keys are down),
    </para>
  </listitem>
  <listitem>
    <para>
AND EITHER the grab window is an ancestor of (or is) the focus window
OR the grab window is a descendent of the focus window and contains the pointer,
    </para>
  </listitem>
  <listitem>
    <para>
AND a passive grab on the same device and button/key combination does not 
exist on any ancestor of the grab window,
    </para>
  </listitem>
  <listitem>
    <para>
THEN the device is actively grabbed, as for
<function>XGrabDevice ,</function>
the last-grab time is set to the time at which the button was pressed
(as transmitted in the
<function>DeviceButtonPress</function>
event), and the 
<function>DeviceButtonPress</function>
event is reported.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
The interpretation of the remaining arguments is as for 
<function>XGrabDevice .</function>
The active grab is terminated automatically when logical state of the
device has all buttons released (independent of the logical state of 
the modifier keys).
</para>
<para>
<!-- .LP -->
Note that the logical state of a device (as seen by means of the X protocol)
may lag the physical state if device event processing is frozen.
</para>
<para>
<!-- .LP -->
A modifier of
<function>AnyModifier</function>
is equivalent to issuing the request for all
possible modifier combinations (including the combination of no
modifiers).  
It is not required that all modifiers specified have
currently assigned keycodes.
A button of
<function>AnyButton</function>
is equivalent to issuing
the request for all possible buttons.
Otherwise, it is not required that the 
specified button be assigned to a physical button.
</para>
<para>
<!-- .LP -->
<xref linkend='XGrabDeviceButton' xrefstyle='select: title'/>
generates a
<function>BadAccess</function>
error if some other client has issued a 
<xref linkend='XGrabDeviceButton' xrefstyle='select: title'/>
with the same device and button combination on the same window.  
When using
<function>AnyModifier</function>
or
<function>AnyButton ,</function>
the request fails completely and the X server generates a
<function>BadAccess</function>
error and no grabs are
established if there is a conflicting grab for any combination.
</para>
<para>
<!-- .LP -->
<xref linkend='XGrabDeviceButton' xrefstyle='select: title'/>
can generate
<function>BadAccess , </function>
<function>BadClass ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
<function>BadValue ,</function>
and
<function>BadWindow</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To release a passive grab of a button on an extension device, use 
<function>XUngrabDeviceButton .</function>
<!-- .sM -->
<funcsynopsis id='XUngrabDeviceButton'>
<funcprototype>
  <funcdef>int <function> XUngrabDeviceButton</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>unsignedint<parameter> button</parameter></paramdef>
  <paramdef>unsignedint<parameter> modifiers</parameter></paramdef>
  <paramdef>XDevice<parameter> *modifier_device</parameter></paramdef>
  <paramdef>Window<parameter> ungrab_window</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>button</emphasis>
    </term>
    <listitem>
      <para>
Specifies the code of the button that is to be ungrabbed.  You can pass
either a button or
<function>AnyButton .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifiers</emphasis>
    </term>
    <listitem>
      <para>
Specifies the set of keymasks.  This mask is the bitwise inclusive OR
of these keymask bits:
<function>ShiftMask ,</function>
<function>LockMask ,</function>
<function>ControlMask , </function>
<function>Mod1Mask ,</function>
<function>Mod2Mask ,</function>
<function>Mod3Mask ,</function>
<function>Mod4Mask ,</function>
and
<function>Mod5Mask .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      
    </term>
    <listitem>
      <para>
You can also pass
<function>AnyModifier ,</function>
which is equivalent to issuing the ungrab key 
request for all possible modifier combinations (including the combination
of no modifiers).
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modifier_device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose modifiers are to be used.  If NULL is 
specified, the core X keyboard is used as the modifier_device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>ungrab_window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of a window associated with the device specified above.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XUngrabDeviceButton' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XUngrabButton'><function>XUngrabButton</function></olink>
function.  It releases an explicit passive grab for a button
on an extension device.
That device must have previously been opened using the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function, or a
<function>BadDevice</function>
error will result.
</para>
<para>
<!-- .LP -->
A modifier of
<function>AnyModifier</function>
is equivalent to issuing the request for all
possible modifier combinations (including the combination of no
modifiers).  
</para>
<para>
<!-- .LP -->
<xref linkend='XUngrabDeviceButton' xrefstyle='select: title'/>
can generate
<function>BadAlloc , </function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
<function>BadValue ,</function>
and
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Thawing_a_Device">
<title>Thawing a Device</title>
<!-- .XS -->
<!-- (SN Thawing a Device -->
<!-- .XE -->
<para>
<!-- .LP -->
To allow further events to be processed when a device has been frozen, use
<function>XAllowDeviceEvents .</function>
<!-- .sM -->
<funcsynopsis id='XAllowDeviceEvents'>
<funcprototype>
  <funcdef>int <function> XAllowDeviceEvents</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> event_mode</parameter></paramdef>
  <paramdef>Time<parameter> time</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_mode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the event mode.  You can pass one of these constants:
<function>AsyncThisDevice ,</function>
<function>SyncThisDevice ,</function>
<function>AsyncOtherDevices ,</function>
<function>ReplayThisDevice ,</function>
<function>AsyncAll ,</function>
or
<function>SyncAll .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>time</emphasis>
    </term>
    <listitem>
      <para>
Specifies the time.  This may be either a timestamp expressed in
milliseconds, or
<function>CurrentTime .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XAllowDeviceEvents' xrefstyle='select: title'/>
releases some queued events if the client has caused a device to freeze.
It has no effect if the specified time is earlier than the last-grab 
time of the most recent active grab for the client and device, 
or if the specified time is later than the current X server time.
The following describes the processing that occurs depending on what constant
you pass to the event_mode argument:
</para>
<itemizedlist>
  <listitem>
    <para>
<function>AsyncThisDevice</function>
    </para>
  </listitem>
  <listitem>
    <para>
If the specified device is frozen by the client, event processing for that 
continues as usual.  If the device is frozen multiple times by the client on 
behalf of multiple separate grabs, 
<function>AsyncThisDevice</function>
thaws for all.
<function>AsyncThisDevice</function>
has no effect if the specified device is not frozen by the 
client, but the device need not be grabbed by the client.
    </para>
  </listitem>
  <listitem>
    <para>
<function>SyncThisDevice</function>
    </para>
  </listitem>
  <listitem>
    <para>
If the specified device is frozen and actively grabbed by the client,
event processing for that device continues normally until the next 
key or button event is reported to the client.
At this time, 
the specified device again appears to freeze.
However, if the reported event causes the grab to be released,
the specified device does not freeze.
<function>SyncThisDevice</function>
has no effect if the specified device is not frozen by the client
or is not grabbed by the client.
    </para>
  </listitem>
  <listitem>
    <para>
<function>ReplayThisDevice</function>
    </para>
  </listitem>
  <listitem>
    <para>
If the specified device is actively grabbed by the client
and is frozen as the result of an event having been sent to the client
(either from the activation of a 
<function>GrabDeviceButton</function>
or from a previous
<function>AllowDeviceEvents</function>
with mode 
<function>SyncThisDevice , </function>
but not from a
<function>Grab ),</function>
the grab is released and that event is completely reprocessed.
This time, however, the request ignores any passive grabs at or above 
(toward the root) the grab-window of the grab just released.
The request has no effect if the specified device is not grabbed by the client
or if it is not frozen as the result of an event.
    </para>
  </listitem>
  <listitem>
    <para>
<function>AsyncOtherDevices</function>
    </para>
  </listitem>
  <listitem>
    <para>
If the remaining devices are frozen by the client,
event processing for them continues as usual.
If the other devices are frozen multiple times  by the client on behalf of 
multiple separate grabs,
<function>AsyncOtherDevices</function>
``thaws'' for all.
<function>AsyncOtherDevices</function>
has no effect if the devices are not frozen by the client,
but those devices need not be grabbed by the client.
    </para>
  </listitem>
  <listitem>
    <para>
<function>SyncAll</function>
    </para>
  </listitem>
  <listitem>
    <para>
If all devices are frozen by the client,
event processing (for all devices) continues normally until the next
button or key event is reported
to the client for a grabbed device,
at which time the devices again appear to
freeze.  However, if the reported event causes the grab to be released,
then the devices do not freeze (but if any device is still
grabbed, then a subsequent event for it will still cause all devices
to freeze).  
<function>SyncAll</function>
has no effect unless all devices are frozen by the client.
If any device is frozen twice
by the client on behalf of two separate grabs, 
<function>SyncAll</function>
"thaws" for both (but a subsequent freeze for 
<function>SyncAll</function>
will freeze each device only once).
    </para>
  </listitem>
  <listitem>
    <para>
<function>AsyncAll</function>
    </para>
  </listitem>
  <listitem>
    <para>
If all devices are frozen by the
client, event processing (for all devices) continues normally.
If any device is frozen multiple times by the client on behalf of multiple
separate grabs, 
<function>AsyncAll</function>
``thaws ''for all.
If any device is frozen twice by the client on behalf of two separate grabs,
<function>AsyncAll</function>
``thaws'' for both.
<function>AsyncAll</function>
has no effect unless all devices are frozen by the client.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
<function>AsyncThisDevice ,</function>
<function>SyncThisDevice ,</function>
and
<function>ReplayThisDevice </function>
have no effect on the processing of events from the remaining devices.
<function>AsyncOtherDevices</function>
has no effect on the processing of events from the specified device.
When the event_mode is
<function>SyncAll</function>
or
<function>AsyncAll ,</function>
the device parameter is ignored.
</para>
<para>
<!-- .LP -->
It is possible for several grabs of different devices (by the same 
or different clients) to be active simultaneously.
If a device is frozen on behalf of any grab,
no event processing is performed for the device.
It is possible for a single device to be frozen because of several grabs.
In this case,
the freeze must be released on behalf of each grab before events can 
again be processed.
</para>
<para>
<!-- .LP -->
<xref linkend='XAllowDeviceEvents' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and 
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Controlling_Device_Focus">
<title>Controlling Device Focus</title>
<!-- .XS -->
<!-- (SN Controlling Device Focus -->
<!-- .XE -->
<para>
<!-- .LP -->
The current focus window for an extension input device can be 
determined using the
<xref linkend='XGetDeviceFocus' xrefstyle='select: title'/>
function.
Extension devices are focused using the
<xref linkend='XSetDeviceFocus' xrefstyle='select: title'/>
function in the same way that the keyboard is focused using the core
<olink targetdoc='libX11' targetptr='XSetInputFocus'><function>XSetInputFocus</function></olink>
function, except that a device ID is passed as
a function parameter.  One additional focus state,
<function>FollowKeyboard ,</function>
is provided for extension devices.
</para>
<para>
<!-- .LP -->
To get the current focus state, revert state,
and focus time of an extension device, use
<function>XGetDeviceFocus .</function>
<!-- .sM -->
<funcsynopsis id='XGetDeviceFocus'>
<funcprototype>
  <funcdef>int <function> XGetDeviceFocus</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>Window<parameter> *focus_return</parameter></paramdef>
  <paramdef>int<parameter> *revert_to_return</parameter></paramdef>
  <paramdef>Time<parameter> *focus_time_return</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>focus_return</emphasis>
    </term>
    <listitem>
      <para>
Specifies the address of a variable into which the server can return the ID of
the window that contains the device focus or one of the constants
<function>None ,</function>
<function>PointerRoot ,</function>
or
<function>FollowKeyboard .  </function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>revert_to_return</emphasis>
    </term>
    <listitem>
      <para>
Specifies the address of a variable into which the server can
return the current revert_to status for the device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>focus_time_return</emphasis>
    </term>
    <listitem>
      <para>
Specifies the address of a variable into which the server can
return the focus time last set for the device.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceFocus' xrefstyle='select: title'/>
returns the focus state, the revert-to state,
and the last-focus-time for an extension input device.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceFocus' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and
<function>BadMatch</function>
errors.
<!-- .sp  -->
</para>
<para>
<!-- .LP -->
To set the focus of an extension device, use
<function>XSetDeviceFocus .</function>
<!-- .sM -->
<funcsynopsis id='XSetDeviceFocus'>
<funcprototype>
  <funcdef>int <function> XSetDeviceFocus</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>Window<parameter> focus</parameter></paramdef>
  <paramdef>int<parameter> revert_to</parameter></paramdef>
  <paramdef>Time<parameter> time</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>focus</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of the window to which the device's focus should be set.
This may be a window ID, or
<function>PointerRoot ,</function>
<function>FollowKeyboard ,</function>
or
<function>None .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>revert_to</emphasis>
    </term>
    <listitem>
      <para>
Specifies to which window the focus of the device should revert
if the focus window becomes not viewable.  One of the following
constants may be passed:
<function>RevertToParent ,</function>
<function>RevertToPointerRoot ,</function>
<function>RevertToNone ,</function>
or
<function>RevertToFollowKeyboard .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>time</emphasis>
    </term>
    <listitem>
      <para>
Specifies the time.  You can pass either a timestamp, expressed in
milliseconds, or
<function>CurrentTime .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSetDeviceFocus' xrefstyle='select: title'/>
changes the focus for an extension input device and the 
last-focus-change-time.  It has no effect if the specified 
time is earlier than the 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.
This function causes the X server to generate
<function>DeviceFocusIn</function>
and 
<function>DeviceFocusOut</function>
events.
</para>
<para>
<!-- .LP -->
The action taken by the server when this function is requested depends
on the value of the focus argument:
</para>
<itemizedlist>
  <listitem>
    <para>
If the focus argument is
<function>None ,</function>
all input events from this device will be discarded until a new focus window
is set.  In this case, the revert_to argument is ignored.
    </para>
  </listitem>
  <listitem>
    <para>
If the focus argument is a window ID, it becomes the focus
window of the device.  If an input event from the device would normally
be reported to this window or to one of its inferiors, the event is 
reported normally.  Otherwise, the event is reported relative to the focus 
window.
    </para>
  </listitem>
  <listitem>
    <para>
If the focus argument is
<function>PointerRoot ,</function>
the focus window is dynamically taken to be the root window 
of whatever screen the pointer is on at each input event.
In this case, the revert_to argument is ignored.
    </para>
  </listitem>
  <listitem>
    <para>
If the focus argument is
<function>FollowKeyboard ,   </function>
the focus window is dynamically taken to be the same as the focus
of the X keyboard at each input event.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
The specified focus window must be viewable at the time
<xref linkend='XSetDeviceFocus' xrefstyle='select: title'/>
is called.  Otherwise, it generates a
<function>BadMatch</function>
error.
If the focus window later becomes not viewable,
the X server evaluates the revert_to argument
to determine the new focus window.
</para>
<itemizedlist>
  <listitem>
    <para>
If the revert_to argument is
<function>RevertToParent ,</function>
the focus reverts to the parent (or the closest viewable ancestor),
and the new revert_to value is taken to be
<function>RevertToNone .  </function>
    </para>
  </listitem>
  <listitem>
    <para>
If the revert_to argument is
<function>RevertToPointerRoot ,</function>
<function>RevertToFollowKeyboard ,</function>
or
<function>RevertToNone ,</function>
the focus reverts to that value.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
When the focus reverts,
the X server generates
<function>DeviceFocusIn</function>
and
<function>DeviceFocusOut</function>
events, but the last-focus-change time is not affected.
</para>
<para>
<!-- .LP -->
<xref linkend='XSetDeviceFocus' xrefstyle='select: title'/>
can generate
<function>BadDevice ,</function>
<function>BadMatch , </function>
<function>BadValue ,</function>
and
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Controlling_Device_Feedback">
<title>Controlling Device Feedback</title>
<!-- .XS -->
<!-- (SN Controlling Device Feedback -->
<!-- .XE -->
<para>
<!-- .LP -->
To determine the current feedback settings of an extension input device, use
<function>XGetFeedbackControl .</function>
<!-- .sM -->
<funcsynopsis id='XGetFeedbackControl'>
<funcprototype>
  <funcdef>XFeedbackState * <function> XGetFeedbackControl</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> *num_feedbacks_return</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_feedbacks_return</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of feedbacks supported by the device.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetFeedbackControl' xrefstyle='select: title'/>
returns a list of
<function>FeedbackState</function>
structures that describe the feedbacks supported by the specified device.
There is an
<function>XFeedbackState</function>
structure for each class of feedback.  These are of 
variable length, but the first three members are common to all.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
} XFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The common members are as follows:
</para>
<itemizedlist>
  <listitem>
    <para>
The class member identifies the class of feedback.
It may be compared to constants defined in the file
<function>&lt; X11/extensions/XI.h &gt;.</function>
Currently defined feedback constants include:
<function>KbdFeedbackClass , </function>
<function>PtrFeedbackClass ,</function>
<function>StringFeedbackClass ,</function>
<function>IntegerFeedbackClass , </function>
<function>LedFeedbackClass ,</function>
and
<function>BellFeedbackClass .</function>
    </para>
  </listitem>
  <listitem>
    <para>
The length member specifies the length of the
<function>FeedbackState</function>
structure and can be used by clients to traverse the list.
    </para>
  </listitem>
  <listitem>
    <para>
The id member uniquely identifies a feedback for a given device and class.
This allows a device to support more than one feedback of the same class.
Other feedbacks of other classes or devices may have the same ID.
<!-- .sp -->
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
Those feedbacks equivalent to those
supported by the core keyboard are reported in class
<function>KbdFeedback</function>
using the
<function>XKbdFeedbackState</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int click;
     int percent;
     int pitch;
     int duration;
     int led_mask;
     int global_auto_repeat;
     char auto_repeats[32];
} XKbdFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The additional members of the
<function>XKbdFeedbackState</function>
structure report the current state of the feedback:
</para>
<itemizedlist>
  <listitem>
    <para>
The click member specifies the key-click volume and has a value in the range
0 (off) to 100 (loud).
    </para>
  </listitem>
  <listitem>
    <para>
The percent member specifies the bell volume and has a value in the range
0 (off) to 100 (loud).
    </para>
  </listitem>
  <listitem>
    <para>
The pitch member specifies the bell pitch in Hz. The range of the value is 
implementation-dependent.
    </para>
  </listitem>
  <listitem>
    <para>
The duration member specifies the duration in milliseconds of the bell.
    </para>
  </listitem>
  <listitem>
    <para>
The led_mask member is a bit mask that describes the current state of up to 
32 LEDs.  A value of 1 in a bit indicates that the corresponding LED is on.
    </para>
  </listitem>
  <listitem>
    <para>
The global_auto_repeat member has a value of
<function>AutoRepeatModeOn</function>
or
<function>AutoRepeatModeOff .</function>
    </para>
  </listitem>
  <listitem>
    <para>
The auto_repeats member is a bit vector.  Each bit set to 1 indicates
that auto-repeat is enabled for the corresponding key.  The vector is
represented as 32 bytes.  Byte N (from 0) contains the bits for keys
8N to 8N + 7, with the least significant bit in the byte representing
key 8N.
<!-- .sp -->
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
Those feedbacks equivalent to those
supported by the core pointer are reported in class
<function>PtrFeedback</function>
using the
<function>XPtrFeedbackState</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int accelNum;
     int accelDenom;
     int threshold;
} XPtrFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The additional members of the
<function>XPtrFeedbackState</function>
structure report the current state of the feedback:
</para>
<itemizedlist>
  <listitem>
    <para>
The accelNum member returns the numerator for the acceleration multiplier.
    </para>
  </listitem>
  <listitem>
    <para>
The accelDenom member returns the denominator for the acceleration multiplier.
    </para>
  </listitem>
  <listitem>
    <para>
The accelDenom member returns the threshold for the acceleration.
<!-- .sp -->
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
Integer feedbacks are those capable of displaying integer numbers
and reported via the
<function>XIntegerFeedbackState</function>
structure.
The minimum and maximum values that they can display are reported.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int resolution;
     int minVal;
     int maxVal;
} XIntegerFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The additional members of the
<function>XIntegerFeedbackState</function>
structure report the capabilities of the feedback:
</para>
<itemizedlist>
  <listitem>
    <para>
The resolution member specifies the number of digits that the feedback
can display.
    </para>
  </listitem>
  <listitem>
    <para>
The minVal member specifies the minimum value that the feedback can display.
    </para>
  </listitem>
  <listitem>
    <para>
The maxVal specifies the maximum value that the feedback can display.
<!-- .sp -->
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
String feedbacks are those that can display character information
and are reported via the
<function>XStringFeedbackState</function>
structure.
Clients set these feedbacks by passing a list of 
<function>KeySyms</function>
to be displayed.
The 
<xref linkend='XGetFeedbackControl' xrefstyle='select: title'/>
function returns the
set of key symbols that the feedback can display, as well as the 
maximum number of symbols that can be displayed.
The
<function>XStringFeedbackState</function>
structure is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int max_symbols;
     int  num_syms_supported;
     KeySym *syms_supported;
} XStringFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The additional members of the
<function>XStringFeedbackState</function>
structure report the capabilities of the feedback:
</para>
<itemizedlist>
  <listitem>
    <para>
The max_symbols member specifies the maximum number of symbols
that can be displayed.
    </para>
  </listitem>
  <listitem>
    <para>
The syms_supported member is a pointer to the list of supported symbols.
    </para>
  </listitem>
  <listitem>
    <para>
The num_syms_supported member specifies the length of the list of supported symbols.
<!-- .sp -->
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
Bell feedbacks are those that can generate a sound
and are reported via the
<function>XBellFeedbackState</function>
structure.
Some implementations may support a bell as part of a
<function>KbdFeedback</function>
feedback.  Class
<function>BellFeedback</function>
is provided for implementations that do not choose to do
so and for devices that support multiple feedbacks that can produce sound.
The meaning of the members is the same as that of the corresponding fields in
the 
<function>XKbdFeedbackState</function>
structure.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int percent;
     int pitch;
     int duration;
} XBellFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Led feedbacks are those that can generate a light and are reported via the
<function>XLedFeedbackState</function>
structure.
Up to 32 lights per feedback are supported.  
Each bit in led_mask
corresponds to one supported light, and the corresponding bit in led_values
indicates whether that light is currently on (1) or off (0).
Some implementations may support leds as part of a
<function>KbdFeedback</function>
feedback.
Class 
<function>LedFeedback</function>
is provided for implementations that do not choose to do
so and for devices that support multiple led feedbacks.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     Mask led_values;
     Mask led_mask;
} XLedFeedbackState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetFeedbackControl' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and
<function>BadMatch</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To free the information returned by the
<xref linkend='XGetFeedbackControl' xrefstyle='select: title'/>
function, use 
<function>XFreeFeedbackList .</function>
<!-- .sM -->
<funcsynopsis id='XFreeFeedbackList'>
<funcprototype>
  <funcdef>void <function> XFreeFeedbackList</function></funcdef>
  <paramdef>XFeedbackState<parameter> *list</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>list</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pointer to the 
<function>XFeedbackState</function>
structure returned by
a previous call to
<function>XGetFeedbackControl .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XFreeFeedbackList' xrefstyle='select: title'/>
frees the list of feedback control information.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To change the settings of a feedback on an extension device, use
<function>XChangeFeedbackControl .</function>
This function modifies the current control values of the specified feedback
using information passed in the appropriate
<function>XFeedbackControl</function>
structure for the feedback.
Which values are modified depends on the valuemask passed.
<!-- .sM -->
<funcsynopsis id='XChangeFeedbackControl'>
<funcprototype>
  <funcdef>int <function> XChangeFeedbackControl</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>unsignedlong<parameter> valuemask</parameter></paramdef>
  <paramdef>XFeedbackControl<parameter> *value</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>valuemask</emphasis>
    </term>
    <listitem>
      <para>
Specifies one value for each bit in the mask (least to most significant
bit).  The values are associated with the feedbacks for the specified
device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>value</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the
<function>XFeedbackControl</function>
structure.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XChangeFeedbackControl' xrefstyle='select: title'/>
controls the device characteristics described by the
<function>XFeedbackControl</function>
structure. 
There is an
<function>XFeedbackControl</function>
structure for each class of feedback.  
These are of variable length, but the first 
three members are common to all and are as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
} XFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Feedback class 
<function>KbdFeedback</function>
controls feedbacks equivalent to those provided by the core keyboard using the
<function>KbdFeedbackControl</function>
structure, which is defined as follows:.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int click;
     int percent;
     int pitch;
     int duration;
     int led_mask;
     int led_value;
     int key;
     int auto_repeat_mode;
} XKbdFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
This class controls the device characteristics described by the
<function>XKbdFeedbackControl</function>
structure.  These include the key_click_percent,
global_auto_repeat, and individual key auto-repeat.  Valid modes
are
<function>AutoRepeatModeOn ,</function>
<function>AutoRepeatModeOff ,</function>
and
<function>AutoRepeatModeDefault .</function>
</para>
<para>
<!-- .LP -->
Valid masks are as follows:
<!-- .sM -->
</para>

<literallayout class="monospaced">

#define   DvKeyClickPercent           (1>&lt;&lt;0)
#define   DvPercent                   (1>&lt;&lt;0)
#define   DvPitch                     (1>&lt;&lt;0)
#define   DvDuration                  (1>&lt;&lt;0)
#define   DvLed                       (1>&lt;&lt;0)
#define   DvLedMode                   (1>&lt;&lt;0)
#define   DvKey                       (1>&lt;&lt;0)
#define   DvAutoRepeatMode            (1>&lt;&lt;0)
</literallayout>

<para>
<!-- .LP -->
Feedback class
<function>PtrFeedback</function>
controls feedbacks equivalent to those provided by the core pointer using the
<function>PtrFeedbackControl</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int accelNum;
     int accelDenom;
     int threshold;
} XPtrFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Which values are modified depends on the valuemask passed.
</para>
<para>
<!-- .LP -->
Valid masks are as follows:
<!-- .sM -->
</para>

<literallayout class="monospaced">
#define    DvAccelnum        (1L&lt;&lt;0)
#define    DvAccelDenom      (1L&lt;&lt;1)
#define    DvThreshold       (1L&lt;&lt;2)
</literallayout>


<para>
<!-- .LP -->
<!-- .eM -->
The acceleration, expressed as a fraction, is a multiplier for movement. 
For example,
specifying 3/1 means that the device moves three times as fast as normal.
The fraction may be rounded arbitrarily by the X server.  
Acceleration takes effect only if the device moves more than threshold pixels at
once and applies only to the amount beyond the value in the threshold argument.
Setting a value to -1 restores the default.
The values of the accelNumerator and threshold fields must be nonzero for
the pointer values to be set.
Otherwise, the parameters will be unchanged.
Negative values generate a
<function>BadValue</function>
error, as does a zero value
for the accelDenominator field.
</para>
<para>
<!-- .LP -->
This request fails with a
<function>BadMatch</function>
error if the specified device is not currently reporting relative motion.
If a device that is capable of reporting both relative and absolute motion
has its mode changed from
<function>Relative</function>
to
<function>Absolute</function>
by an
<xref linkend='XSetDeviceMode' xrefstyle='select: title'/>
request, valuator control values
will be ignored by the server while the device is in that mode.
</para>
<para>
<!-- .LP -->
Feedback class
<function>IntegerFeedback</function>
controls integer feedbacks displayed on input devices and are
reported via the
<function>IntegerFeedbackControl</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int int_to_display;
} XIntegerFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Valid masks are as follows:
<!-- .sM -->
</para>

<literallayout class="monospaced">

#define   DvInteger           (1L&lt;&lt;0)
</literallayout>

<para>
<!-- .LP -->
<!-- .eM -->
Feedback class
<function>StringFeedback</function>
controls string feedbacks displayed on input devices
and reported via the
<function>StringFeedbackControl</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int num_keysyms;
     KeySym *syms_to_display;
} XStringFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Valid masks are as follows:
<!-- .sM -->
</para>
<literallayout class="monospaced">

#define   DvString           (1L&lt;&lt;0)
</literallayout>

<para>
<!-- .LP -->
<!-- .eM -->
Feedback class
<function>BellFeedback</function>
controls a bell on an input device and is reported via the
<function>BellFeedbackControl</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int percent;
     int pitch;
     int duration;
} XBellFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Valid masks are as follows:
<!-- .sM -->
</para>


<literallayout class="monospaced">

#define   DvPercent                   (1L&lt;&lt;1)
#define   DvPitch                     (1L&lt;&lt;2)
#define   DvDuration                  (1L&lt;&lt;3)
</literallayout>

<para>
<!-- .LP -->
<!-- .eM -->
Feedback class
<function>LedFeedback</function>
controls lights on an input device and are reported via the
<function>LedFeedbackControl</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID class;
     int length;
     XID id;
     int led_mask;
     int led_values;
} XLedFeedbackControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
Valid masks are as follows:
<!-- .sM -->
</para>

<literallayout class="monospaced">

#define   DvLed                       (1L&lt;&lt;4)
#define   DvLedMode                   (1L&lt;&lt;5)
</literallayout>

<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XChangeFeedbackControl' xrefstyle='select: title'/>
can generate
<function>BadDevice ,</function>
<function>BadFeedBack ,</function>
<function>BadMatch ,</function>
and
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Ringing_a_Bell_on_an_Input_Device">
<title>Ringing a Bell on an Input Device</title>
<!-- .XS -->
<!-- (SN Ringing a Bell on an Input Device -->
<!-- .XE -->
<para>
<!-- .LP -->
To ring a bell on an extension input device, use
<function>XDeviceBell .</function>
<!-- .sM -->
<funcsynopsis id='XDeviceBell'>
<funcprototype>
  <funcdef>int <function> XDeviceBell</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>XIDfeedbackclass,<parameter> feedbackid</parameter></paramdef>
  <paramdef>int<parameter> percent</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>feedbackclass</emphasis>
    </term>
    <listitem>
      <para>
Specifies the feedbackclass.  Valid values are
<function>KbdFeedbackClass</function>
and
<function>BellFeedbackClass .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>feedbackid</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of the feedback that has the bell.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>percent</emphasis>
    </term>
    <listitem>
      <para>
Specifies the volume in the range -100 (quiet) to 100 percent (loud).
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XDeviceBell' xrefstyle='select: title'/>
is analogous to the core 
<olink targetdoc='libX11' targetptr='XBell'><function>XBell</function></olink>
function.  It rings the specified bell on the specified input device feedback,
using the specified volume.
The specified volume is relative to the base volume for the feedback.
If the value for the percent argument is not in the range -100 to 100
inclusive, a
<function>BadValue</function>
error results.
The volume at which the bell rings when the percent argument is nonnegative is:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
       base - [(base * percent) / 100] + percent
</literallayout>
</para>
<para>
<!-- .LP -->
The volume at which the bell rings
when the percent argument is negative is:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
       base + [(base * percent) / 100]
</literallayout>
</para>
<para>
<!-- .LP -->
To change the base volume of the bell, use
<function>XChangeFeedbackControl .</function>
</para>
<para>
<!-- .LP -->
<xref linkend='XDeviceBell' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Controlling_Device_Encoding">
<title>Controlling Device Encoding</title>
<!-- .XS -->
<!-- (SN Controlling Device Encoding -->
<!-- .XE -->
<para>
<!-- .LP -->
To get the key mapping of an extension device that supports input class 
<function>Keys ,</function>
use 
<function>XGetDeviceKeyMapping .</function>
<!-- .sM -->
<funcsynopsis id='XGetDeviceKeyMapping'>
<funcprototype>
  <funcdef>KeySym * <function> XGetDeviceKeyMapping</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>KeyCode<parameter> first_keycode_wanted</parameter></paramdef>
  <paramdef>int<parameter> keycode_count</parameter></paramdef>
  <paramdef>int<parameter> *keysyms_per_keycode_return</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>first_keycode_wanted</emphasis>
    </term>
    <listitem>
      <para>
Specifies the first keycode that is to be returned.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>keycode_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of keycodes that are to be returned.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>keysyms_per_keycode_return</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of keysyms per keycode.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceKeyMapping' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XGetKeyboardMapping'><function>XGetKeyboardMapping</function></olink>
function.  
It returns the symbols for the specified number of keycodes for the 
specified extension device.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceKeyMapping' xrefstyle='select: title'/>
returns the symbols for the 
specified number of keycodes for the 
specified extension device, starting with the specified keycode.
The first_keycode_wanted must be greater than or equal to
min-keycode as returned 
by the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request (else a 
<function>BadValue</function>
error results). The following value:
<literallayout class="monospaced">
first_keycode_wanted + keycode_count - 1
</literallayout>
</para>
<para>
<!-- .LP -->
must be less than or equal to max-keycode as returned 
by the 
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request (else a 
<function>BadValue</function>
error results).
</para>
<para>
<!-- .LP -->
The number of elements in the keysyms list is as follows:
<literallayout class="monospaced">
keycode_count * keysyms_per_keycode_return
</literallayout>
And KEYSYM number N (counting from zero) for keycode K has an index
(counting from zero), in keysyms, of the following:
<literallayout class="monospaced">
(K - first_keycode_wanted) * keysyms_per_keycode_return + N
</literallayout>
</para>
<para>
<!-- .LP -->
The keysyms_per_keycode_return value is chosen arbitrarily by the server
to be large enough to report all requested symbols.
A special KEYSYM value of
<function>NoSymbol</function>
is used to fill in unused elements for individual keycodes.
</para>
<para>
<!-- .LP -->
To free the data returned by this function, use
<olink targetdoc='libX11' targetptr='XFree'><function>XFree</function></olink>.
</para>
<para>
<!-- .LP -->
If the specified device has not first been opened by this client via
<function>XOpenDevice ,</function>
this request will fail with a
<function>BadDevice</function>
error.
If that device does not support input class
<function>Keys ,</function>
this request will fail with a 
<function>BadMatch</function>
error.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceKeyMapping' xrefstyle='select: title'/>
can generate
<function>BadDevice ,</function>
<function>BadMatch ,</function>
and
<function>BadValue</function>
errors.
<!-- .sp  -->
</para>
<para>
<!-- .LP -->
To change the keyboard mapping of an extension device that supports input class 
<function>Keys ,</function>
use 
<function>XChangeDeviceKeyMapping .</function>
<!-- .sM -->
<funcsynopsis id='XChangeDeviceKeyMapping'>
<funcprototype>
  <funcdef>int <function> XChangeDeviceKeyMapping</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> first_keycode</parameter></paramdef>
  <paramdef>int<parameter> keysyms_per_keycode</parameter></paramdef>
  <paramdef>KeySym<parameter> *keysyms</parameter></paramdef>
  <paramdef>int<parameter> num_codes</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>first_keycode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the first keycode that is to be changed.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>keysyms_per_keycode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the keysyms that are to be used.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>keysyms</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to an array of keysyms.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_codes</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of keycodes that are to be changed.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XChangeDeviceKeyMapping' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XChangeKeyboardMapping'><function>XChangeKeyboardMapping</function></olink>
function.  
It defines the symbols for the specified number of keycodes for the 
specified extension keyboard device.
</para>
<para>
<!-- .LP -->
If the specified device has not first been opened by this client via
<function>XOpenDevice ,</function>
this request will fail with a
<function>BadDevice</function>
error.
If the specified device does not support input class
<function>Keys ,</function>
this request will fail with a
<function>BadMatch</function>
error.
</para>
<para>
<!-- .LP -->
The number of elements in the keysyms list must be a multiple of
keysyms_per_keycode.  Otherwise,
<xref linkend='XChangeDeviceKeyMapping' xrefstyle='select: title'/>
generates a
<function>BadLength</function>
error.
The specified first_keycode must be greater than or equal to
the min_keycode value returned by the
<function>ListInputDevices</function>
request, or this request will fail with a
<function>BadValue</function>
error.  In addition, if the following expression is not less than
the max_keycode value returned by the
<function>ListInputDevices</function>
request, the request will fail with a
<function>BadValue</function>
error:
<literallayout class="monospaced">
       first_keycode + (num_codes / keysyms_per_keycode) - 1
</literallayout>
</para>
<para>
<!-- .LP -->
<xref linkend='XChangeDeviceKeyMapping' xrefstyle='select: title'/>
can generate
<function>BadAlloc ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
and
<function>BadValue</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To obtain the keycodes that are used as modifiers on an 
extension device that supports input class
<function>Keys ,</function>
use
<function>XGetDeviceModifierMapping .</function>
<!-- .sM -->
<funcsynopsis id='XGetDeviceModifierMapping'>
<funcprototype>
  <funcdef>XModifierKeymap * <function> XGetDeviceModifierMapping</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceModifierMapping' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XGetModifierMapping'><function>XGetModifierMapping</function></olink>
function.  
The
<xref linkend='XGetDeviceModifierMapping' xrefstyle='select: title'/>
function returns a newly created
<function>XModifierKeymap</function>
structure that contains the keys being used as
modifiers for the specified device.
The structure should be freed after use with
<function>XFreeModifierMapping .</function>
If only zero values appear in the set for any modifier,
that modifier is disabled.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceModifierMapping' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and
<function>BadMatch</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To set which keycodes are to be used as modifiers for an extension device, use
<function>XSetDeviceModifierMapping .</function>
<!-- .sM -->
<funcsynopsis id='XSetDeviceModifierMapping'>
<funcprototype>
  <funcdef>int <function> XSetDeviceModifierMapping</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>XModifierKeymap<parameter> *modmap</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>modmap</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the
<function>XModifierKeymap</function>
structure.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSetDeviceModifierMapping' xrefstyle='select: title'/>
is analogous to the core
<olink targetdoc='libX11' targetptr='XSetModifierMapping'><function>XSetModifierMapping</function></olink>
function.  
The 
<xref linkend='XSetDeviceModifierMapping' xrefstyle='select: title'/>
function specifies the keycodes of the keys, if any, 
that are to be used as modifiers.  A zero value means
that no key should be used.  No two arguments can have the same nonzero
keycode value.  Otherwise,
<xref linkend='XSetDeviceModifierMapping' xrefstyle='select: title'/>
generates a
<function>BadValue</function>
error.
There are eight modifiers, and the modifiermap member of the 
<function>XModifierKeymap</function>
structure contains eight sets of max_keypermod 
keycodes, one for each modifier in the order 
<function>Shift ,</function>
<function>Lock ,</function>
<function>Control ,</function>
<function>Mod1 ,</function>
<function>Mod2 ,</function>
<function>Mod3 ,</function>
<function>Mod4 ,</function>
and
<function>Mod5 .</function>
Only nonzero keycodes have meaning in each set, and zero keycodes
are ignored.
In addition, all of the nonzero keycodes must be in the range specified by 
min_keycode and max_keycode reported by the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
function.
Otherwise,
<olink targetdoc='libX11' targetptr='XSetModifierMapping'><function>XSetModifierMapping</function></olink>
generates a
<function>BadValue</function>
error.
No keycode may appear twice in the entire map. 
Otherwise, it generates a
<function>BadValue</function>
error.
</para>
<para>
<!-- .LP -->
A X server can impose restrictions on how modifiers can be changed, 
for example,
if certain keys do not generate up transitions in hardware or if multiple
modifier keys are not supported.  
If some such restriction is violated, 
the status reply is
<function>MappingFailed ,</function>
and none of the modifiers are changed.
If the new keycodes specified for a modifier differ from those
currently defined and any (current or new) keys for that modifier are
in the logically down state, 
the status reply is
<function>MappingBusy , </function>
and none of the modifiers are changed.
<olink targetdoc='libX11' targetptr='XSetModifierMapping'><function>XSetModifierMapping</function></olink>
generates a
<function>DeviceMappingNotify</function>
event on a
<function>MappingSuccess</function>
status.
</para>
<para>
<!-- .LP -->
<xref linkend='XSetDeviceModifierMapping' xrefstyle='select: title'/>
can generate
<function>BadAlloc ,</function>
<function>BadDevice ,</function>
<function>BadMatch ,</function>
and
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Controlling_Button_Mapping">
<title>Controlling Button Mapping</title>
<!-- .XS -->
<!-- (SN Controlling Button Mapping -->
<!-- .XE -->
<para>
<!-- .LP -->
To set the mapping of the buttons on an extension device, use
<function>XSetDeviceButtonMapping .</function>
<!-- .sM -->
<funcsynopsis id='XSetDeviceButtonMapping'>
<funcprototype>
  <funcdef>int <function> XSetDeviceButtonMapping</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>unsignedchar<parameter> map[]</parameter></paramdef>
  <paramdef>int<parameter> nmap</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>map</emphasis>
    </term>
    <listitem>
      <para>
Specifies the mapping list.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>nmap</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of items in the mapping list.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSetDeviceButtonMapping' xrefstyle='select: title'/>
sets the mapping of the buttons on an extension device.
If it succeeds, the X server generates a
<function>DeviceMappingNotify</function>
event, and
<xref linkend='XSetDeviceButtonMapping' xrefstyle='select: title'/>
returns
<function>MappingSuccess .</function>
Elements of the list are indexed starting from one.
The length of the list must be the same as
<xref linkend='XGetDeviceButtonMapping' xrefstyle='select: title'/>
would return, or a 
<function>BadValue</function>
error results.
The index is a button number, and the element of the list
defines the effective number.
A zero element disables a button, and elements are not restricted in
value by the number of physical buttons.
However, no two elements can have the same nonzero value, or a
<function>BadValue</function>
error results.
If any of the buttons to be altered are logically in the down state,
<xref linkend='XSetDeviceButtonMapping' xrefstyle='select: title'/>
returns
<function>MappingBusy ,</function>
and the mapping is not changed.
</para>
<para>
<!-- .LP -->
<xref linkend='XSetDeviceButtonMapping' xrefstyle='select: title'/>
can generate
<function>BadDevice ,</function>
<function>BadMatch ,</function>
and
<function>BadValue</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To get the button mapping, use
<function>XGetDeviceButtonMapping .</function>
<!-- .sM -->
<funcsynopsis id='XGetDeviceButtonMapping'>
<funcprototype>
  <funcdef>int <function> XGetDeviceButtonMapping</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>unsignedchar<parameter> map_return[]</parameter></paramdef>
  <paramdef>int<parameter> nmap</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>map_return</emphasis>
    </term>
    <listitem>
      <para>
Specifies the mapping list.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>nmap</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of items in the mapping list.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceButtonMapping' xrefstyle='select: title'/>
returns the current mapping of the specified extension device.
Elements of the list are indexed starting from one.
<xref linkend='XGetDeviceButtonMapping' xrefstyle='select: title'/>
returns the number of physical buttons actually on the pointer.
The nominal mapping for the buttons is the identity mapping: map[i]=i.
The nmap argument specifies the length of the array where the button
mapping is returned, and only the first nmap elements are returned 
in map_return.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceButtonMapping' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and
<function>BadMatch</function>
errors.
</para>
</sect3>
<sect3 id="Obtaining_the_State_of_a_Device">
<title>Obtaining the State of a Device</title>
<!-- .XS -->
<!-- (SN Obtaining the State of a Device -->
<!-- .XE -->
<para>
<!-- .LP -->
To obtain information that describes the state of the keys, buttons, and 
valuators of an extension device, use
<function>XQueryDeviceState .</function>
<!-- .sM -->
<funcsynopsis id='XQueryDeviceState'>
<funcprototype>
  <funcdef>XDeviceState * <function> XQueryDeviceState</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XQueryDeviceState' xrefstyle='select: title'/>
returns a pointer to an
<function>XDeviceState</function>
structure, which points to a list of
structures that describe the state of the keys, buttons, and valuators 
on the device:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID device_id;
     int num_classes;
     XInputClass *data;
} XDeviceState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The structures are of variable length, but the first 
two members are common to all and are as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     unsigned char class;
     unsigned char length;
} XInputClass;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The class member contains a class identifier.  This identifier can be
compared with constants defined in the file 
<function>&lt; X11/extensions/XI.h &gt;.</function>
Currently defined constants are:
<function>KeyClass ,</function>
<function>ButtonClass ,</function>
and
<function>ValuatorClass .</function>
</para>
<para>
<!-- .LP -->
The length member contains the length of the structure and can be used
by clients to traverse the list.
</para>
<para>
<!-- .LP -->
The 
<function>XValuatorState</function>
structure describes the current state of the valuators
on the device.
The num_valuators member contains the number of valuators
on the device.
The mode member is a mask whose bits report the data mode
and other state information for the device.
The following bits are currently defined:
<literallayout class="monospaced">
<!-- .TA .5i 1.5i 2.5i -->
<!-- .ta .5i 1.5i 2.5i -->
     DeviceMode     1 &lt;&lt; 0     Relative = 0, Absolute = 1
     ProximityState     1 &lt;&lt; 1     InProximity = 0, OutOfProximity = 1
</literallayout>
The valuators member contains a pointer to an array of integers that
describe the current value of the valuators.
If the mode is 
<function>Relative ,</function>
these values are undefined.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     unsigned char class;
     unsigned char length;
     unsigned char num_valuators;
     unsigned char mode;
     int *valuators;
} XValuatorState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The
<function>XKeyState</function>
structure describes the current state of the keys
on the device.  Byte N (from 0) contains the
bits for key 8N to 8N + 7 with the least significant bit in the
byte representing key 8N.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     unsigned char class;
     unsigned char length;
     short num_keys;
     char keys[32];
} XKeyState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The
<function>XButtonState</function>
structure describes the current state of the buttons
on the device.  Byte N (from 0) contains the bits for button 8N to 8N + 7
with the least significant bit in the
byte representing button 8N.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     unsigned char class;
     unsigned char length;
     short num_buttons;
     char buttons[32];
} XButtonState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XQueryDeviceState' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To free the data returned by this function, use
<function>XFreeDeviceState .</function>
<!-- .sM -->
<funcsynopsis id='XFreeDeviceState'>
<funcprototype>
  <funcdef>void <function> XFreeDeviceState</function></funcdef>
  <paramdef>XDeviceState<parameter> *state</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>state</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pointer to the
<function>XDeviceState</function>
data returned by a previous call to
<function>XQueryDeviceState .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XFreeDeviceState' xrefstyle='select: title'/>
frees the device state data.
</para>
</sect3>
</sect2>
<sect2 id="Events">
<title>Events</title>
<!-- .XS -->
<!-- (SN Events -->
<!-- .XE -->
<para>
<!-- .LP -->
The input extension creates input events analogous to the core input events.
These extension input events are generated by manipulating one of the
extension input devices.
The remainder of this section discusses the following X Input Extension
event topics:
</para>
<itemizedlist>
  <listitem>
    <para>
Event types
    </para>
  </listitem>
  <listitem>
    <para>
Event classes
    </para>
  </listitem>
  <listitem>
    <para>
Event structures
    </para>
  </listitem>
</itemizedlist>
<sect3 id="Event_Types">
<title>Event Types</title>
<!-- .XS -->
<!-- (SN Event Types -->
<!-- .XE -->
<para>
<!-- .LP -->
Event types are integer numbers that a client can use to determine what
kind of event it has received.  The client compares the type field of 
the event structure with known event types to make this determination.
</para>
<para>
<!-- .LP -->
The core input event types are constants and are defined in the header file
<function>&lt; X11/X.h &gt;.</function>
Extension event types are not constants.  Instead, they
are dynamically allocated by the extension's request to the X server
when the extension is initialized.  Because of this, extension event
types must be obtained by the client from the server.
</para>
<para>
<!-- .LP -->
The client program determines the event type for an extension event by using
the information returned by the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
request.
This type can then be used for comparison with the type field
of events received by the client.
</para>
<para>
<!-- .LP -->
Extension events propagate up the window hierarchy in the same manner
as core events.  If a window is not interested in an extension event, 
it usually propagates to the closest ancestor that is interested,
unless the dont_propagate list prohibits it.
Grabs of extension devices may alter the set of windows that receive a particular
extension event.
</para>
<para>
<!-- .LP -->
The following table lists the event category and its associated event
type or types.
</para>

<informaltable>
  <tgroup cols='2' align='center'>
  <colspec colname='c1'/>
  <colspec colname='c2'/>
  <thead>
    <row>
      <entry>Event Category</entry>
      <entry>Event Type</entry>
    </row>
  </thead>
  <tbody>
    <row>
      <entry>Device key</entry>
      <entry><function>DeviceKeyPress</function></entry>
    </row>
    <row>
      <entry></entry>
      <entry><function>DeviceKeyRelease</function></entry>
    </row>
    <row>
      <entry>Device motion</entry>
      <entry><function>DeviceButtonPress</function></entry>
    </row>
    <row>
      <entry></entry>
      <entry><function>DeviceButtonRelease</function></entry>
    </row>
    <row>
      <entry></entry>
      <entry><function>DeviceMotionNotify</function></entry>
    </row>
    <row>
      <entry>Device input focus</entry>
      <entry><function>DeviceFocusIn</function></entry>
    </row>
    <row>
      <entry></entry>
      <entry><function>DeviceFocusOut</function></entry>
    </row>
    <row>
      <entry>Device state notification</entry>
      <entry><function>DeviceStateNotify</function></entry>
    </row>
    <row>
      <entry>Device proximity</entry>
      <entry><function>ProximityIn</function></entry>
    </row>
    <row>
      <entry></entry>
      <entry><function>ProximityOut</function></entry>
    </row>
    <row>
      <entry>Device mapping</entry>
      <entry><function>DeviceMappingNotify</function></entry>
    </row>
    <row>
      <entry>Device change</entry>
      <entry><function>ChangeDeviceNotify</function></entry>
    </row>
  </tbody>
  </tgroup>
</informaltable>

</sect3>
<sect3 id="Event_Classes">
<title>Event Classes</title>
<!-- .XS -->
<!-- (SN Event Classes -->
<!-- .XE -->
<para>
<!-- .LP -->
Event classes are integer numbers that are used in the same way as the
core event masks.  They are used by a client program to indicate to the
server which events that client program wishes to receive.
</para>
<para>
<!-- .LP -->
The core input event masks are constants and are defined in the header file
<function>&lt; X11/X.h &gt;.</function>
Extension event classes are not constants.  Instead, they are dynamically
allocated by the extension's request to the X server
when the extension is initialized.  Because of this, extension event
classes must be obtained by the client from the server.
</para>
<para>
<!-- .LP -->
The event class for an extension event and device is obtained from
information returned by the 
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function. 
This class can then be used in an
<xref linkend='XSelectExtensionEvent' xrefstyle='select: title'/>
request to ask that events of that type from that device be sent to
the client program.
</para>
<para>
<!-- .LP -->
For
<function>DeviceButtonPress</function>
events, the client may specify whether
or not an implicit passive grab should be done when the button is
pressed.  If the client wants to guarantee that it will receive a
<function>DeviceButtonRelease</function>
event for each
<function>DeviceButtonPress</function>
event it receives, it should specify the
<function>DeviceButtonPressGrab</function>
class in addition to the
<function>DeviceButtonPress</function>
class.
This restricts the client in that only one client at a time
may request
<function>DeviceButtonPress</function>
events from the same device and
window if any client specifies this class.
</para>
<para>
<!-- .LP -->
If any client has specified the
<function>DeviceButtonPressGrab</function>
class, any requests by any other client that specify the same device
and window and specify either
<function>DeviceButtonPress</function>
or
<function>DeviceButtonPressGrab</function>
will cause an
<function>Access</function>
error to be generated.
</para>
<para>
<!-- .LP -->
If only the
<function>DeviceButtonPress</function>
class is specified, no implicit passive grab will be done when a button
is pressed on the device.
Multiple clients may use this class to specify the same device and
window combination.
</para>
<para>
<!-- .LP -->
The client may also select
<function>DeviceMotion</function>
events only when a button is down.
It does this by specifying the event classes 
<function>DeviceButton1Motion</function>
through
<function>DeviceButton5Motion .  </function>
An input device will support only
as many button motion classes as it has buttons.
</para>
</sect3>
<sect3 id="Event_Structures">
<title>Event Structures</title>
<!-- .XS -->
<!-- (SN Event Structures -->
<!-- .XE -->
<para>
<!-- .LP -->
Each extension event type has a corresponding structure declared in
<function>&lt; X11/extensions/XInput.h &gt;.</function>
All event structures have the following common members:
<variablelist>
  <varlistentry>
    <term>
      type
    </term>
    <listitem>
      <para>
Set to the event type number that uniquely identifies it.  For example,
when the X server reports a
<function>DeviceKeyPress</function>
event to a client application, it sends an
<function>XDeviceKeyPressEvent</function>
structure.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      serial
    </term>
    <listitem>
      <para>
Set from the serial number reported in the protocol but expanded from the
16-bit least significant bits to a full 32-bit value.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      send_event
    </term>
    <listitem>
      <para>
Set to 
<function>True</function>
if the event came from an
<olink targetdoc='libX11' targetptr='XSendEvent'><function>XSendEvent</function></olink>
request.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      display
    </term>
    <listitem>
      <para>
Set to a pointer to a structure that defines the display 
on which the event was read.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
Extension event structures report the current position of the X pointer.
In addition, if the device reports motion data and is reporting absolute data,
the current value of any valuators the device contains is also reported.
</para>
<sect4 id="Device_Key_Events">
<title>Device Key Events</title>
<!-- .XS -->
<!-- (SN Device Key Events -->
<!-- .XE -->
<para>
<!-- .LP -->
Key events from extension devices contain all the information that is
contained in a key event from the X keyboard.  In addition, they contain
a device ID and report the current value of any valuators on the device,
if that device is reporting absolute data.
If data for more than six valuators is being reported, more than one
key event will be sent.
The axes_count member contains the number of axes that are being
reported.  The server sends as many of these events as are
needed to report the device data.  Each event contains the total number
of axes reported in the axes_count member and the first axis reported
in the current event in the first_axis member.
If the device supports input class
<function>Valuators , </function>
but is not reporting absolute mode data,
the axes_count member  contains zero (0).
</para>
<para>
<!-- .LP -->
The location reported in 
the x, y and x_root, y_root members is the location of the core X pointer.
</para>
<para>
<!-- .LP -->
The
<function>XDeviceKeyEvent</function>
structure is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     int type;                      /* of event */
     unsigned long serial;          /* # of last request processed */
     Bool send_event;               /* true if from SendEvent request */
     Display *display;              /* Display the event was read from */
     Window window;                 /* "event" window reported relative to */
     XID deviceid;
     Window root;                   /* root window event occurred on */
     Window subwindow;              /* child window */
     Time time;                     /* milliseconds */
     int x, y;                      /* x, y coordinates in event window */
     int x_root;                    /* coordinates relative to root */
     int y_root;                    /* coordinates relative to root */
     unsigned int state;            /* key or button mask */
     unsigned int keycode;          /* detail */
     Bool same_screen;              /* same screen flag */
     unsigned int device_state;     /* device key or button mask */
     unsigned char axes_count;
     unsigned char first_axis;
     int axis_data[6];
} XDeviceKeyEvent;

typedef XDeviceKeyEvent XDeviceKeyPressedEvent;
typedef XDeviceKeyEvent XDeviceKeyReleasedEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="Device_Button_Events">
<title>Device Button Events</title>
<!-- .XS -->
<!-- (SN Device Button Events -->
<!-- .XE -->
<para>
<!-- .LP -->
Button events from extension devices contain all the information that is
contained in a button event from the X pointer.  In addition, they contain
a device ID and report the current value of any valuators on the device
if that device is reporting absolute data.
If data for more than six valuators is being reported, more than one
button event may be sent.
The axes_count member contains the number of axes that are being
reported.  The server sends as many of these events as are
needed to report the device data.  Each event contains the total number
of axes reported in the axes_count member and the first axis reported
in the current event in the first_axis member.
If the device supports input class
<function>Valuators , </function>
but is not reporting absolute mode data,
the axes_count member contains zero (0).
</para>
<para>
<!-- .LP -->
The location reported in 
the x, y and x_root, y_root members is the location of the core X pointer.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     int type;                      /* of event */
     unsigned long serial;          /* # of last request processed by server */
     Bool send_event;               /* true if from a SendEvent request */
     Display *display;              /* Display the event was read from */
     Window window;                 /* "event" window reported relative to */
     XID deviceid;
     Window root;                   /* root window that the event occurred on */
     Window subwindow;              /* child window */
     Time time;                     /* milliseconds */
     int x, y;                      /* x, y coordinates in event window */
     int x_root;                    /* coordinates relative to root */
     int y_root;                    /* coordinates relative to root */
     unsigned int state;            /* key or button mask */
     unsigned int button;           /* detail */
     Bool same_screen;              /* same screen flag */
     unsigned int device_state;     /* device key or button mask */
     unsigned char axes_count;
     unsigned char first_axis;
     int axis_data[6];
} XDeviceButtonEvent;

typedef XDeviceButtonEvent XDeviceButtonPressedEvent;
typedef XDeviceButtonEvent XDeviceButtonReleasedEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="Device_Motion_Events">
<title>Device Motion Events</title>
<!-- .XS -->
<!-- (SN Device Motion Events -->
<!-- .XE -->
<para>
<!-- .LP -->
Motion events from extension devices contain all the information that is
contained in a motion event from the X pointer.  In addition, they contain
a device ID and report the current value of any valuators on the device.
</para>
<para>
<!-- .LP -->
The location reported in 
the x, y and x_root, y_root members is the location of the core X pointer, 
and so is 2-dimensional.
</para>
<para>
<!-- .LP -->
Extension motion devices may report motion data for a variable number of 
axes.  
The axes_count member contains the number of axes that are being
reported.  The server sends as many of these events as are
needed to report the device data.  Each event contains the total number
of axes reported in the axes_count member and the first axis reported
in the current event in the first_axis member.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     int type;                          /* of event */
     unsigned long serial;              /* # of last request processed by server */
     Bool send_event;                   /* true if from a SendEvent request */
     Display *display;                  /* Display the event was read from */
     Window window;                     /* "event" window reported relative to */
     XID deviceid;
     Window root;                       /* root window that the event occurred on */
     Window subwindow;                  /* child window */
     Time time;                         /* milliseconds */
     int x, y;                          /* x, y coordinates in event window */
     int x_root;                        /* coordinates relative to root */
     int y_root;                        /* coordinates relative to root */
     unsigned int state;                /* key or button mask */
     char is_hint;                      /* detail */
     Bool same_screen;                  /* same screen flag */
     unsigned int device_state;         /* device key or button mask */
     unsigned char axes_count;
     unsigned char first_axis;
     int axis_data[6];
} XDeviceMotionEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="Device_Focus_Events">
<title>Device Focus Events</title>
<!-- .XS -->
<!-- (SN Device Focus Events -->
<!-- .XE -->
<para>
<!-- .LP -->
These events are equivalent to the core focus events.
They contain the same information, with the addition
of a device ID to identify which device has had a focus change,
and a timestamp.
</para>
<para>
<!-- .LP -->
<function>DeviceFocusIn</function>
and
<function>DeviceFocusOut</function>
events are generated for
focus changes of extension devices in the same manner as core focus
events are generated.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 2.5i -->
<!-- .ta .5i 2.5i -->
typedef struct {
     int type;                      /* of event */
     unsigned long serial;          /* # of last request processed by server */
     Bool send_event;               /* true if this came from a SendEvent request */
     Display *display;              /* Display the event was read from */
     Window window;                 /* "event" window it is reported relative to */
     XID deviceid;
     int mode;                      /* NotifyNormal, NotifyGrab, NotifyUngrab */
     int detail;
                                    /*
                                     * NotifyAncestor, NotifyVirtual, NotifyInferior, 
                                     * NotifyNonLinear,NotifyNonLinearVirtual, NotifyPointer,
                                     * NotifyPointerRoot, NotifyDetailNone 
                                     */
     Time time;
} XDeviceFocusChangeEvent;

typedef XDeviceFocusChangeEvent XDeviceFocusInEvent;
typedef XDeviceFocusChangeEvent XDeviceFocusOutEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="Device_StateNotify_Event">
<title>Device StateNotify Event</title>
<!-- .XS -->
<!-- (SN Device StateNotify Event -->
<!-- .XE -->
<para>
<!-- .LP -->
This event is analogous to the core keymap event but
reports the current state of the device for each
input class that it supports.
It is generated after every
<function>DeviceFocusIn</function>
event and
<function>EnterNotify</function>
event and is delivered to clients who have selected
<function>XDeviceStateNotify</function>
events.
</para>
<para>
<!-- .LP -->
If the device supports input class
<function>Valuators ,</function>
the mode member in the
<function>XValuatorStatus</function>
structure is a bitmask that reports the device mode,
proximity state, and other state information.
The following bits are currently defined:
<literallayout class="monospaced">
<!-- .TA .5i 1.5i -->
<!-- .ta .5i 1.5i -->
     0x01     Relative = 0, Absolute = 1
     0x02     InProximity = 0, OutOfProximity = 1
</literallayout>
</para>
<para>
<!-- .LP -->
If the device supports more valuators than can be reported in a single
<function>XEvent ,</function>
multiple
<function>XDeviceStateNotify</function>
events will be generated.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     unsigned char class;
     unsigned char length;
} XInputClass;

typedef struct {
     int type;
     unsigned long serial;     /* # of last request processed by server */
     Bool send_event;          /* true if this came from a SendEvent request */
     Display *display;         /* Display the event was read from */
     Window window;
     XID deviceid;
     Time time;
     int num_classes;
     char data[64];
} XDeviceStateNotifyEvent;     

typedef struct {
     unsigned char class;
     unsigned char length;
     unsigned char num_valuators;
     unsigned char mode;
     int valuators[6];
} XValuatorStatus;

typedef struct {
     unsigned char class;
     unsigned char length;
     short num_keys;
     char keys[32];
} XKeyStatus;

typedef struct {
     unsigned char class;
     unsigned char length;
     short num_buttons;
     char buttons[32];
} XButtonStatus;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="Device_Mapping_Event">
<title>Device Mapping Event</title>
<!-- .XS -->
<!-- (SN Device Mapping Event -->
<!-- .XE -->
<para>
<!-- .LP -->
This event is equivalent to the core
<function>MappingNotify</function>
event.
It notifies client programs when the mapping of keys,
modifiers, or buttons on an extension device has changed.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     int type;
     unsigned long serial;     
     Bool send_event;
     Display *display;
     Window window;
     XID deviceid;
     Time time;
     int request;
     int first_keycode;
     int count;
} XDeviceMappingEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="ChangeDeviceNotify_Event">
<title>ChangeDeviceNotify Event</title>
<!-- .XS -->
<!-- (SN ChangeDeviceNotify Event -->
<!-- .XE -->
<para>
<!-- .LP -->
This event has no equivalent in the core protocol.  It notifies client
programs when one of the core devices has been changed.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     int type;
     unsigned long serial;
     Bool send_event;
     Display *display;
     Window window;
     XID deviceid;
     Time time;
     int request;
} XChangeDeviceNotifyEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
<sect4 id="Proximity_Events">
<title>Proximity Events</title>
<!-- .XS -->
<!-- (SN Proximity Events -->
<!-- .XE -->
<para>
<!-- .LP -->
These events have no equivalent in the core protocol.  Some input
devices such as graphics tablets or touchscreens may send these
events to indicate that a stylus has moved into or out of contact
with a positional sensing surface.
</para>
<para>
<!-- .LP -->
The event contains the current value of any valuators on the device
if that device is reporting absolute data.
If data for more than six valuators is being reported, more than one
proximity event may be sent.
The axes_count member contains the number of axes that are being
reported.  The server sends as many of these events as are
needed to report the device data.  Each event contains the total number
of axes reported in the axes_count member and the first axis reported
in the current event in the first_axis member.
If the device supports input class
<function>Valuators , </function>
but is not reporting absolute mode data,
the axes_count member contains zero (0).
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i 3i -->
<!-- .ta .5i 3i -->
typedef struct {
     int type;                 /* ProximityIn or ProximityOut */        
     unsigned long serial;     /* # of last request processed by server */
     Bool send_event;          /* true if this came from a SendEvent request */
     Display *display;         /* Display the event was read from */
     Window window;      
     XID deviceid;
     Window root;            
     Window subwindow;      
     Time time;            
     int x, y;            
     int x_root, y_root;  
     unsigned int state;           
     Bool same_screen;     
     unsigned int device_state;   /* device key or button mask */
     unsigned char axes_count;
     unsigned char first_axis;
     int axis_data[6];
} XProximityNotifyEvent;

typedef XProximityNotifyEvent XProximityInEvent;
typedef XProximityNotifyEvent XProximityOutEvent;
</literallayout>
<!-- .eM -->
</para>
</sect4>
</sect3>
</sect2>
<sect2 id="Event_Handling_Functions">
<title>Event Handling Functions</title>
<!-- .XS -->
<!-- (SN Event Handling Functions -->
<!-- .XE -->
<para>
<!-- .LP -->
This section discusses the X Input Extension
event handling functions that allow you to:
</para>
<itemizedlist>
  <listitem>
    <para>
Determine the extension version
    </para>
  </listitem>
  <listitem>
    <para>
List the available devices
    </para>
  </listitem>
  <listitem>
    <para>
Enable and disable extension devices
    </para>
  </listitem>
  <listitem>
    <para>
Change the mode of a device
    </para>
  </listitem>
  <listitem>
    <para>
Initialize valuators on an input device
    </para>
  </listitem>
  <listitem>
    <para>
Get input device controls
    </para>
  </listitem>
  <listitem>
    <para>
Change input device controls
    </para>
  </listitem>
  <listitem>
    <para>
Select extension device events
    </para>
  </listitem>
  <listitem>
    <para>
Determine selected device events
    </para>
  </listitem>
  <listitem>
    <para>
Control event propagation
    </para>
  </listitem>
  <listitem>
    <para>
Send an event
    </para>
  </listitem>
  <listitem>
    <para>
Get motion history
    </para>
  </listitem>
</itemizedlist>
<sect3 id="Determining_the_Extension_Version">
<title>Determining the Extension Version</title>
<!-- .XS -->
<!-- (SN Determining the Extension Version -->
<!-- .XE -->
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XGetExtensionVersion'>
<funcprototype>
  <funcdef>XExtensionVersion * <function> XGetExtensionVersion</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>char<parameter> *name</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>name</emphasis>
    </term>
    <listitem>
      <para>
Specifies the name of the desired extension.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetExtensionVersion' xrefstyle='select: title'/>
allows a client to determine whether a server supports
the desired version of the input extension.
</para>
<para>
<!-- .LP -->
The 
<function>XExtensionVersion</function>
structure returns information about the version of the extension
supported by the server and is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     Bool present;   
     short major_version;
     short minor_version;
} XExtensionVersion;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The major and minor versions can be compared with constants defined in
the header file 
<function>&lt; X11/extensions/XI.h &gt;.</function>
Each version is a superset of the previous versions.
</para>
<para>
<!-- .LP -->
You should use 
<olink targetdoc='libX11' targetptr='XFree'><function>XFree</function></olink>.
to free the data returned by this function.
</para>
</sect3>
<sect3 id="Listing_Available_Devices">
<title>Listing Available Devices</title>
<!-- .XS -->
<!-- (SN Listing Available Devices -->
<!-- .XE -->
<para>
<!-- .LP -->
A client program that wishes to access a specific device
must first determine whether that device is connected to the X server.  This
is done through the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
function, which will return a list of all devices that can be opened
by the X server.  The client program can use one
of the names defined in the
<function>&lt; X11/extensions/XI.h &gt;</function>
header file in an
<olink targetdoc='libX11' targetptr='XInternAtom'><function>XInternAtom</function></olink>
request to determine the device type of the desired device.  This type 
can then be compared with the device types returned by the 
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request.
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XListInputDevices'>
<funcprototype>
  <funcdef>XDeviceInfo * <function> XListInputDevices</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>int<parameter> *ndevices</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>ndevices</emphasis>
    </term>
    <listitem>
      <para>
Specifies the address of a variable into which the server
can return the number of input devices available to the X server.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
allows a client to determine which devices 
are available for X input and information about those devices.
An array of
<function>XDeviceInfo</function>
structures is returned, with one element in the array for each device.
The number of devices is returned in the ndevices argument.
</para>
<para>
<!-- .LP -->
The X pointer device and X keyboard device are reported, as well as
all available extension input devices.  The use member of the 
<function>XDeviceInfo</function>
structure specifies the current use of the device.
If the value of this member is 
<function>IsXPointer ,</function>
the device is the X pointer device.  If the value is
<function>IsXKeyboard ,</function>
the device is the X keyboard device.  If the value is
<function>IsXExtensionDevice ,</function>
the device is available for use as an extension input device.
</para>
<para>
<!-- .LP -->
Each
<function>XDeviceInfo</function>
entry contains a pointer to a list of structures 
that describe the characteristics of each class
of input supported by that device.  The num_classes member
contains the number of entries in that list.
</para>
<para>
<!-- .LP -->
If the device supports input class
<function>Valuators ,</function>
one of the structures pointed to by the
<function>XDeviceInfo</function>
structure will be an
<function>XValuatorInfo</function>
structure.  The axes member of that structure
contains the address of an array of
<function>XAxisInfo</function>
structures.
There is one element in this array for each axis of motion
reported by the device.  The number of elements in this 
array is contained in the num_axes element of the 
<function>XValuatorInfo</function>
structure.
The size of the motion buffer for the device is
reported in the motion_buffer member of the
<function>XValuatorInfo</function>
structure.
</para>
<para>
<!-- .LP -->
The
<function>XDeviceInfo</function>
structure is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct _XDeviceInfo {
     XID id;        
     Atom type;
     char *name;
     int num_classes;
     int use;
     XAnyClassPtr inputclassinfo;
} XDeviceInfo;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The structures pointed to by the
<function>XDeviceInfo</function>
structure are defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct _XKeyInfo {
     XID class;
     int length;
     unsigned short min_keycode;
     unsigned short max_keycode;
     unsigned short num_keys;
} XKeyInfo;

typedef struct _XButtonInfo {
     XID class;
     int length;
     short num_buttons;
} XButtonInfo;

typedef struct _XValuatorInfo {
     XID class;
     int length;
     unsigned char num_axes;
     unsigned char mode;
     unsigned long motion_buffer;
     XAxisInfoPtr axes;
} XValuatorInfo;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The
<function>XAxisInfo</function>
structure pointed to by the
<function>XValuatorInfo</function>
structure is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct _XAxisInfo {
     int resolution;
     int min_value;
     int max_value;
} XAxisInfo;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The following atom names are defined in the 
<function>&lt; X11/extensions/XI.h &gt;</function>
header file.
<literallayout class="monospaced">
<!-- .TA 2i -->
<!-- .ta 2i -->
MOUSE     QUADRATURE
TABLET     SPACEBALL
KEYBOARD     DATAGLOVE
TOUCHSCREEN     EYETRACKER
TOUCHPAD     CURSORKEYS
BUTTONBOX     FOOTMOUSE
BARCODE     ID_MODULE
KNOB_BOX     ONE_KNOB
TRACKBALL     NINE_KNOB\s+1
</literallayout>
</para>
<para>
<!-- .LP -->
These names can be used in an
<olink targetdoc='libX11' targetptr='XInternAtom'><function>XInternAtom</function></olink>
request to return an atom that can be used for comparison
with the type member of the 
<function>XDeviceInfo</function>
structure.
</para>
<para>
<!-- .LP -->
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
returns NULL if there are no input devices to list.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To free the data returned by 
<function>XListInputDevices ,</function>
use
<function>XFreeDeviceList .</function>
<!-- .sp -->
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XFreeDeviceList'>
<funcprototype>
  <funcdef>void <function> XFreeDeviceList</function></funcdef>
  <paramdef>XDeviceInfo<parameter> *list</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>list</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pointer to the
<function>XDeviceInfo</function>
array returned by a previous call to
<function>XListInputDevices .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XFreeDeviceList' xrefstyle='select: title'/>
frees the list of input device information.
</para>
</sect3>
<sect3 id="Enabling_and_Disabling_Extension_Devices">
<title>Enabling and Disabling Extension Devices</title>
<!-- .XS -->
<!-- (SN Enabling and Disabling Extension Devices -->
<!-- .XE -->
<para>
<!-- .LP -->
Each client program that wishes to access an extension device must request
that the server open that device by calling the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
function.
<!-- .sM -->
<funcsynopsis id='XOpenDevice'>
<funcprototype>
  <funcdef>XDevice * <function> XOpenDevice</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XID<parameter> device_id</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device_id</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID that uniquely identifies the device to be opened.
This ID is obtained from the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
opens the device for the requesting client and, on success, returns an
<function>XDevice</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID device_id;
     int num_classes;
     XInputClassInfo *classes;
} XDevice;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The
<function>XDevice</function>
structure contains a pointer to an array of
<function>XInputClassInfo</function>
structures.  Each element in that array
contains information about events of a particular input class supported
by the input device.
</para>
<para>
<!-- .LP -->
The
<function>XInputClassInfo</function>
structure is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     unsigned char input_class;
     unsigned char event_type_base;
} XInputClassInfo;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
A client program can determine the event
type and event class for a given event by using macros defined by the 
input extension.  The name of the macro corresponds to the desired event,
and the macro is passed the structure that describes the device from which
input is desired, for example:
</para>
<para>
<!-- .LP -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
     DeviceKeyPress(XDevice *device, event_type, event_class)
</literallayout>
</para>
<para>
<!-- .LP -->
The macro will fill in the values of the event class to be used in an
<xref linkend='XSelectExtensionEvent' xrefstyle='select: title'/>
request to select the event and the event type to be used in comparing
with the event types of events received via
<olink targetdoc='libX11' targetptr='XNextEvent'><function>XNextEvent</function></olink>.
</para>
<para>
<!-- .LP -->
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
Before terminating, the client program should request that the server close
the device by calling the
<xref linkend='XCloseDevice' xrefstyle='select: title'/>
function.
<!-- .sM -->
<funcsynopsis id='XCloseDevice'>
<funcprototype>
  <funcdef>int <function> XCloseDevice</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device to be closed.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XCloseDevice' xrefstyle='select: title'/>
closes the device for the requesting client and frees the associated
<function>XDevice</function>
structure.
</para>
<para>
<!-- .LP -->
A client may open the same extension device more than once.  Requests
after the first successful one return an additional
<function>XDevice</function>
structure
with the same information as the first, but otherwise have no effect.
A single
<xref linkend='XCloseDevice' xrefstyle='select: title'/>
request will terminate that client's access to the device.
</para>
<para>
<!-- .LP -->
Closing a device releases any active or passive grabs the requesting client
has established.  If the device is frozen only by an active grab of the
requesting client, any queued events are released.
</para>
<para>
<!-- .LP -->
If a client program terminates without closing a device, the server will
automatically close that device on behalf of the client.  This does not
affect any other clients that may be accessing that device.
</para>
<para>
<!-- .LP -->
<xref linkend='XCloseDevice' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
errors.
</para>
</sect3>
<sect3 id="Changing_the_Mode_of_a_Device">
<title>Changing the Mode of a Device</title>
<!-- .XS -->
<!-- (SN Changing the Mode of a Device -->
<!-- .XE -->
<para>
<!-- .LP -->
Some devices are capable of reporting either relative or absolute motion
data. 
To change the mode of a device from relative to absolute, use
<function>XSetDeviceMode .</function>
<!-- .sM -->
<funcsynopsis id='XSetDeviceMode'>
<funcprototype>
  <funcdef>int <function> XSetDeviceMode</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> mode</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose mode should be changed.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>mode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the mode.  You can pass
<function>Absolute</function>
or
<function>Relative .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSetDeviceMode' xrefstyle='select: title'/>
allows a client to request the server to change the mode of a 
device that is capable of reporting either absolute positional data or relative
motion data.  If the device is invalid or if the client has not previously 
requested that the server open the device via an
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
request, this request will fail with a
<function>BadDevice</function>
error.
If the device does not support input class
<function>Valuators</function>
or if it is not capable of reporting the specified mode,
the request will fail with a 
<function>BadMatch</function>
error.
</para>
<para>
<!-- .LP -->
This request will fail and return
<function>DeviceBusy</function>
if another client has already opened the device and requested a different mode.
</para>
<para>
<!-- .LP -->
<xref linkend='XSetDeviceMode' xrefstyle='select: title'/>
can generate
<function>BadDevice ,</function>
<function>BadMatch ,</function>
<function>BadMode ,</function>
and
<function>DeviceBusy</function>
errors.
</para>
</sect3>
<sect3 id="Initializing_Valuators_on_an_Input_Device">
<title>Initializing Valuators on an Input Device</title>
<!-- .XS -->
<!-- (SN Initializing Valuators on an Input Device -->
<!-- .XE -->
<para>
<!-- .LP -->
Some devices that report absolute positional data can be initialized to a 
starting value.  Devices that are capable of reporting relative motion or
absolute positional data may require that their valuators be initialized 
to a starting value after the mode of the device is changed to
<function>Absolute .</function>
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To initialize the valuators on such a device, use 
<function>XSetDeviceValuators .</function>
<!-- .sM -->
<funcsynopsis id='XSetDeviceValuators'>
<funcprototype>
  <funcdef>Status <function> XSetDeviceValuators</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int*valuators,first_valuator,<parameter> num_valuators</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose valuators should be initialized.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>valuators</emphasis>
    </term>
    <listitem>
      <para>
Specifies the values to which each valuator should be set.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>first_valuator</emphasis>
    </term>
    <listitem>
      <para>
Specifies the first valuator to be set.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>num_valuators</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of valuators to be set.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSetDeviceValuators' xrefstyle='select: title'/>
initializes the specified valuators on the specified extension
input device.  Valuators are numbered beginning with zero.  Only the valuators
in the range specified by first_valuator and num_valuators are set.  
A
<function>BadValue</function>
error results if the number of valuators supported by the device 
is less than the following expression:
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
     first_valuator + num_valuators
</literallayout>
</para>
<para>
<!-- .LP -->
If the request succeeds,
<function>Success</function>
is returned.  If the specified device is grabbed by some other client,
the request will fail and a status of
<function>AlreadyGrabbed</function>
will be returned.
</para>
<para>
<!-- .LP -->
<xref linkend='XSetDeviceValuators' xrefstyle='select: title'/>
can generate
<function>BadDevice ,</function>
<function>BadLength ,</function>
<function>BadMatch ,</function>
and 
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Getting_Input_Device_Controls">
<title>Getting Input Device Controls</title>
<!-- .XS -->
<!-- (SN Getting Input Device Controls -->
<!-- .XE -->
<para>
<!-- .LP -->
Some input devices support various configuration controls
that can be queried or changed by clients.  The set of supported
controls will vary from one input device to another.  Requests
to manipulate these controls will fail if either the target
X server or the target input device does not support the 
requested device control.
</para>
<para>
<!-- .LP -->
Each device control has a unique identifier.  Information
passed with each device control varies in length and is mapped
by data structures unique to that device control.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To query a device control, use
<function>XGetDeviceControl .</function>
<!-- .sM -->
<funcsynopsis id='XGetDeviceControl'>
<funcprototype>
  <funcdef>XDeviceControl * <function> XGetDeviceControl</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> control</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose configuration control status is to be returned.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>control</emphasis>
    </term>
    <listitem>
      <para>
Identifies the specific device control to be queried.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceControl' xrefstyle='select: title'/>
returns the current state of the specified device control.
If the target X server does not support that device control, a
<function>BadValue</function>
error is returned.
If the specified device does not support that device control, a
<function>BadMatch</function>
error
is returned.
</para>
<para>
<!-- .LP -->
If the request is successful, a pointer to a generic 
<function>XDeviceState</function>
structure is returned.  The information returned varies according
to the specified control and is mapped by a structure appropriate
for that control.
The first two members are common to all device controls
and are defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID control;
     int length;
} XDeviceState;
\fP
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The control may be compared to constants defined in the file
<function>&lt; X11/extensions/XI.h &gt;.</function>
Currently defined device controls include DEVICE_RESOLUTION.
</para>
<para>
<!-- .LP -->
The information returned for the DEVICE_RESOLUTION control is
defined in the 
<function>XDeviceResolutionState</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID control;
     int length;
     int num_valuators;
     int *resolutions;
     int *min_resolutions;
     int *max_resolutions;
} XDeviceResolutionState;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
This device control returns a list of valuators and the range of 
valid resolutions allowed for each.  Valuators are numbered 
beginning with zero (0).  Resolutions for all valuators on the device are 
returned.  For each valuator i on the device, resolutions[i] returns 
the current setting of the resolution, min_resolutions[i] returns 
the minimum valid setting, and max_resolutions[i] returns the 
maximum valid setting.
</para>
<para>
<!-- .LP -->
When this control is specified,
<xref linkend='XGetDeviceControl' xrefstyle='select: title'/>
fails with a
<function>BadMatch</function>
error if the specified device has no valuators.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceControl' xrefstyle='select: title'/>
can generate
<function>BadMatch</function>
and
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Changing_Input_Device_Controls">
<title>Changing Input Device Controls</title>
<!-- .XS -->
<!-- (SN Changing Input Device Controls -->
<!-- .XE -->
<para>
<!-- .LP -->
Some input devices support various configuration controls
that can be changed by clients.  Typically, this would be
done to initialize the device to a known state or configuration.
The set of supported controls will vary from one input device 
to another.  Requests to manipulate these controls will fail if 
either the target X server or the target input device does not 
support the requested device control.  Setting the device control 
will also fail if the target input device is grabbed by another 
client or is open by another client and has been set to a conflicting
state.
</para>
<para>
<!-- .LP -->
Each device control has a unique identifier.  Information
passed with each device control varies in length and is mapped
by data structures unique to that device control.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To change a device control, use
<function>XChangeDeviceControl .</function>
<!-- .sM -->
<funcsynopsis id='XChangeDeviceControl'>
<funcprototype>
  <funcdef>Status <function> XChangeDeviceControl</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>int<parameter> control</parameter></paramdef>
  <paramdef>XDeviceControl<parameter> *value</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose configuration control status is to be modified.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>control</emphasis>
    </term>
    <listitem>
      <para>
Identifies the specific device control to be changed.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>value</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to an
<function>XDeviceControl</function>
structure that describes which control is to be changed
and how it is to be changed.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XChangeDeviceControl' xrefstyle='select: title'/>
changes the current state of the specified device control.
If the target X server does not support that device control, a
<function>BadValue</function>
error is returned.
If the specified device does not support that device control, a
<function>BadMatch</function>
error is returned.
If another client has the target device grabbed, a status of
<function>AlreadyGrabbed</function>
is returned.
If another client has the device open and has set it to a 
conflicting state, a status of
<function>DeviceBusy</function>
is returned.
If the request fails for any reason, the device control will not
be changed.
</para>
<para>
<!-- .LP -->
If the request is successful, the device control will be changed
and a status of
<function>Success</function>
is returned.
The information passed varies according to the specified control
and is mapped by a structure appropriate for that control.
The first two members are common to all device controls:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID control;
     int length;
} XDeviceControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The control may be set using constants defined in the 
<function>&lt; X11/extensions/XI.h &gt;</function>
header file.
Currently defined device controls include DEVICE_RESOLUTION.
</para>
<para>
<!-- .LP -->
The information that can be changed by the DEVICE_RESOLUTION 
control is defined in the 
<function>XDeviceResolutionControl</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     XID control;
     int length;
     int first_valuator;
     int num_valuators;
     int *resolutions;
} XDeviceResolutionControl;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
This device control changes the resolution of the specified 
valuators on the specified extension input device.  Valuators 
are numbered beginning with zero.  Only the valuators in the range 
specified by first_valuator and num_valuators are set.  A value 
of -1 in the resolutions list indicates that the resolution for 
this valuator is not to be changed.  The num_valuators member
specifies the number of valuators in the resolutions list.
</para>
<para>
<!-- .LP -->
When this control is specified,
<xref linkend='XChangeDeviceControl' xrefstyle='select: title'/>
fails with a
<function>BadMatch</function>
error if the specified device has no valuators.
If a resolution is specified that is not within the range of valid values 
(as returned by
<function>XGetDeviceControl ),</function>
<xref linkend='XChangeDeviceControl' xrefstyle='select: title'/>
fails with a
<function>BadValue</function>
error.
A
<function>BadValue</function>
error results if the number of valuators supported by the device 
is less than the following expression:
</para>
<para>
<!-- .LP    -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
     first_valuator + num_valuators, 
</literallayout>
</para>
<para>
<!-- .LP   -->
<xref linkend='XChangeDeviceControl' xrefstyle='select: title'/>
can generate
<function>BadMatch</function>
and
<function>BadValue</function>
errors.
</para>
</sect3>
<sect3 id="Selecting_Extension_Device_Events">
<title>Selecting Extension Device Events</title>
<!-- .XS -->
<!-- (SN Selecting Extension Device Events -->
<!-- .XE -->
<para>
<!-- .LP -->
To select device input events, use
<function>XSelectExtensionEvent .</function>
The parameters passed are a pointer to 
a list of classes that define the desired event types and devices, a count
of the number of elements in the list, and the ID of the window from which 
events are desired.
<!-- .sM -->
<funcsynopsis id='XSelectExtensionEvent'>
<funcprototype>
  <funcdef>int <function> XSelectExtensionEvent</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>Window<parameter> window</parameter></paramdef>
  <paramdef>XEventClass<parameter> *event_list</parameter></paramdef>
  <paramdef>int<parameter> event_count</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of the window from which the client wishes to receive events.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_list</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to an array of event classes
that specify which events are desired.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of elements in the event_list.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSelectExtensionEvent' xrefstyle='select: title'/>
requests the server to send events that match the events and
devices described by the event list and that come from the requested 
window.  
The elements of the
<function>XEventClass</function>
array are the event_class values
obtained by invoking a macro with the pointer to an
<function>XDevice</function>
structure returned by the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
request.
For example, the
<function>DeviceKeyPress</function>
macro would return the
<function>XEventClass</function>
for
<function>DeviceKeyPress</function>
events from the specified device if it were invoked in the following form:
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
     DeviceKeyPress (XDevice *device, event_type, event_class)
</literallayout>
</para>
<para>
<!-- .LP -->
Macros are defined for the following event classes: 
<literallayout class="monospaced">
<function>DeviceKeyPress</function>
<function>DeviceKeyRelease</function>
<function>DeviceButtonPress</function>
<function>DeviceButtonRelease</function>
<function>DeviceMotionNotify</function>
<function>DeviceFocusIn</function>
<function>DeviceFocusOut</function>
<function>ProximityIn</function>
<function>ProximityOut</function>
<function>DeviceStateNotify</function>
<function>DeviceMappingNotify</function>
<function>ChangeDeviceNotify</function>
<function>DevicePointerMotionHint</function>
<function>DeviceButton1Motion </function>
<function>DeviceButton2Motion</function>
<function>DeviceButton3Motion, </function>
<function>DeviceButton4Motion</function>
<function>DeviceButton5Motion</function>
<function>DeviceButtonMotion,</function>
<function>DeviceOwnerGrabButton</function>
<function>DeviceButtonPressGrab</function>
</literallayout>
</para>
<para>
<!-- .LP -->
To get the next available event from within a client program, use the core
<olink targetdoc='libX11' targetptr='XNextEvent'><function>XNextEvent</function></olink>
function.  This returns the next event whether it
came from a core device or an extension device.
</para>
<para>
<!-- .LP -->
Succeeding
<xref linkend='XSelectExtensionEvent' xrefstyle='select: title'/>
requests using event classes
for the same device as was specified on a previous request will replace
the previous set of selected events from that device with the new set.
</para>
<para>
<!-- .LP -->
<xref linkend='XSelectExtensionEvent' xrefstyle='select: title'/>
can generate
<function>BadAccess , </function>
<function>BadClass ,</function>
<function>BadLength ,</function>
and
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Determining_Selected_Device_Events">
<title>Determining Selected Device Events</title>
<!-- .XS -->
<!-- (SN Determining Selected Device Events -->
<!-- .XE -->
<para>
<!-- .LP -->
To determine which extension events are currently selected from a given
window, use
<function>XGetSelectedExtensionEvents .</function>
<!-- .sM -->
<funcsynopsis id='XGetSelectedExtensionEvents'>
<funcprototype>
  <funcdef>int <function> XGetSelectedExtensionEvents</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>Window<parameter> window</parameter></paramdef>
  <paramdef>int<parameter> *this_client_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> **this_client</parameter></paramdef>
  <paramdef>int<parameter> *all_clients_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> **all_clients</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the ID of the window from which the client wishes to receive events.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>this_client_count</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of elements in the this_client list.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>this_client</emphasis>
    </term>
    <listitem>
      <para>
Returns a list of
<function>XEventClasses</function>
that specify which events are
selected by this client.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>all_clients_count</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of elements in the all_clients list.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>all_clients</emphasis>
    </term>
    <listitem>
      <para>
Returns a list of
<function>XEventClasses</function>
that specify which events are
selected by all clients.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetSelectedExtensionEvents' xrefstyle='select: title'/>
returns pointers to two event class arrays.  
One lists the extension events selected by this client from
the specified window.  The other lists the extension events selected by
all clients from the specified window.  This information is analogous
to that returned in your_event_mask and all_event_masks of the
<function>XWindowAttributes</function>
structure when an 
<olink targetdoc='libX11' targetptr='XGetWindowAttributes'><function>XGetWindowAttributes</function></olink>
request is made.
To free the two arrays returned by this function, use
<olink targetdoc='libX11' targetptr='XFree'><function>XFree</function></olink>.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetSelectedExtensionEvents' xrefstyle='select: title'/>
can generate
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Controlling_Event_Propagation">
<title>Controlling Event Propagation</title>
<!-- .XS -->
<!-- (SN Controlling Event Propagation -->
<!-- .XE -->
<para>
<!-- .LP -->
Extension events propagate up the window hierarchy in the same manner
as core events.  If a window is not interested in an extension event, 
it usually propagates to the closest ancestor that is interested,
unless the dont_propagate list prohibits it.
Grabs of extension devices may alter the set of windows that receive a 
particular extension event.
</para>
<para>
<!-- .LP -->
Client programs may control event propagation through the use
of the following two functions:
<xref linkend='XChangeDeviceDontPropagateList' xrefstyle='select: title'/>
and
<function>XGetDeviceDontPropagateList .  </function>
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XChangeDeviceDontPropagateList'>
<funcprototype>
  <funcdef>int <function> XChangeDeviceDontPropagateList</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>Window<parameter> window</parameter></paramdef>
  <paramdef>int<parameter> event_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> *events</parameter></paramdef>
  <paramdef>int<parameter> mode</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired window.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of elements in the events list.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>events</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the list of XEventClasses.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>mode</emphasis>
    </term>
    <listitem>
      <para>
Specifies the mode.  You can pass
<function>AddToList</function>
or
<function>DeleteFromList .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XChangeDeviceDontPropagateList' xrefstyle='select: title'/>
adds an event to or deletes an event from the do_not_propagate list 
of extension events for the specified window.
There is one list per window, and the list remains for the life of the window.
The list is not altered if a client that changed the list terminates.
</para>
<para>
<!-- .LP -->
Suppression of event propagation is not allowed for all events.  If a
specified
<function>XEventClass</function>
is invalid because suppression of that event is not allowed, a
<function>BadClass</function>
error results.
</para>
<para>
<!-- .LP -->
<xref linkend='XChangeDeviceDontPropagateList' xrefstyle='select: title'/>
can generate
<function>BadClass ,</function>
<function>BadMode ,</function>
and
<function>BadWindow</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XGetDeviceDontPropagateList'>
<funcprototype>
  <funcdef>XEventClass * <function> XGetDeviceDontPropagateList</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>Window<parameter> window</parameter></paramdef>
  <paramdef>int<parameter> *event_count</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired window.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of elements in the array returned by this function.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceDontPropagateList' xrefstyle='select: title'/>
allows a client to determine the do_not_propagate list of extension events
for the specified window.
It returns an array of
<function>XEventClass ,</function>
each
<function>XEventClass</function>
representing a device/event type pair.
To free the data returned by this function, use
<olink targetdoc='libX11' targetptr='XFree'><function>XFree</function></olink>.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceDontPropagateList' xrefstyle='select: title'/>
can generate
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Sending_an_Event">
<title>Sending an Event</title>
<!-- .XS -->
<!-- (SN Sending an Event -->
<!-- .XE -->
<para>
<!-- .LP -->
To send an extension event to another client, use
<function>XSendExtensionEvent .</function>
<!-- .sM -->
<funcsynopsis id='XSendExtensionEvent'>
<funcprototype>
  <funcdef>int <function> XSendExtensionEvent</function></funcdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>Window<parameter> window</parameter></paramdef>
  <paramdef>Bool<parameter> propagate</parameter></paramdef>
  <paramdef>int<parameter> event_count</parameter></paramdef>
  <paramdef>XEventClass<parameter> *event_list</parameter></paramdef>
  <paramdef>XEvent<parameter> *event</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the device whose ID is recorded in the event.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>window</emphasis>
    </term>
    <listitem>
      <para>
Specifies the destination window ID.  You can pass a window ID,
<function>PointerWindow</function>
or
<function>InputFocus .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>propagate</emphasis>
    </term>
    <listitem>
      <para>
Specifies a boolean value that is either
<function>True</function>
or 
<function>False .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_count</emphasis>
    </term>
    <listitem>
      <para>
Specifies the number of elements in the event_list array.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event_list</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to an array of
<function>XEventClass .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>event</emphasis>
    </term>
    <listitem>
      <para>
Specifies a pointer to the event that is to be sent.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XSendExtensionEvent' xrefstyle='select: title'/>
identifies the destination window, determines which clients should receive
the specified event, and ignores any active grabs.
It requires a list of
<function>XEventClass</function>
to be specified.
These are obtained by opening an input device with the
<xref linkend='XOpenDevice' xrefstyle='select: title'/>
request.
</para>
<para>
<!-- .LP -->
<xref linkend='XSendExtensionEvent' xrefstyle='select: title'/>
uses the window argument to identify the destination window as follows:
</para>
<itemizedlist>
  <listitem>
    <para>
If you pass
<function>PointerWindow ,</function>
the destination window is the window that contains the pointer.
    </para>
  </listitem>
  <listitem>
    <para>
If you pass
<function>InputFocus</function>
and if the focus window contains the pointer,
the destination window is the window that contains the pointer.
If the focus window does not contain the pointer,
the destination window is the focus window.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
To determine which clients should receive the specified events, 
<xref linkend='XSendExtensionEvent' xrefstyle='select: title'/>
uses the propagate argument as follows:
</para>
<itemizedlist>
  <listitem>
    <para>
If propagate is
<function>False ,</function>
the event is sent to every client selecting
from the destination window
any of the events specified in the event_list array.
    </para>
  </listitem>
  <listitem>
    <para>
If propagate is
<function>True </function>
and no clients have selected from the destination window
any of the events specified in the event_list array, the destination is 
replaced with the closest ancestor of destination for which some client
has selected one of the specified events and for which no intervening
window has that event in its do_not_propagate mask.
If no such window exists,
or if the window is an ancestor of the focus window, and 
<function>InputFocus</function>
was originally specified as the destination,
the event is not sent to any clients.  Otherwise, the event is reported to every
client selecting on the final destination any of the events specified
in event_list.
    </para>
  </listitem>
</itemizedlist>
<para>
<!-- .LP -->
The event in the
<function>XEvent</function>
structure must be one of the events defined
by the input extension, so that the X server can correctly byte swap the
contents as necessary.  The contents of the event are otherwise unaltered
and unchecked by the X server except to force send_event to
<function>True</function>
in the forwarded event and to set the sequence number in the event correctly.
</para>
<para>
<!-- .LP -->
<xref linkend='XSendExtensionEvent' xrefstyle='select: title'/>
returns zero if the conversion-to-wire protocol failed;
otherwise, it returns nonzero.
</para>
<para>
<!-- .LP -->
<xref linkend='XSendExtensionEvent' xrefstyle='select: title'/>
can generate
<function>BadClass ,</function>
<function>BadDevice ,</function>
<function>BadValue ,</function>
and
<function>BadWindow</function>
errors.
</para>
</sect3>
<sect3 id="Getting_Motion_History">
<title>Getting Motion History</title>
<!-- .XS -->
<!-- (SN Getting Motion History -->
<!-- .XE -->
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XGetDeviceMotionEvents'>
<funcprototype>
  <funcdef>XDeviceTimeCoord * <function> XGetDeviceMotionEvents</function></funcdef>
  <paramdef><parameter> axis_count_return)</parameter></paramdef>
  <paramdef>Display<parameter> *display</parameter></paramdef>
  <paramdef>XDevice<parameter> *device</parameter></paramdef>
  <paramdef>Timestart,<parameter> stop</parameter></paramdef>
  <paramdef>int<parameter> *nevents_return</parameter></paramdef>
  <paramdef>int<parameter> *mode_return</parameter></paramdef>
  <paramdef>int<parameter> *axis_count_return</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>display</emphasis>
    </term>
    <listitem>
      <para>
Specifies the connection to the X server.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>device</emphasis>
    </term>
    <listitem>
      <para>
Specifies the desired device.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>start</emphasis>
    </term>
    <listitem>
      <para>
Specifies the start time.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>stop</emphasis>
    </term>
    <listitem>
      <para>
Specifies the stop time.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>nevents_return</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of positions in the motion buffer returned
for this request.
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>mode_return</emphasis>
    </term>
    <listitem>
      <para>
Returns the mode of the nevents information.
The mode will be one of the following:
<function>Absolute</function>
or
<function>Relative .</function>
      </para>
    </listitem>
  </varlistentry>
  <varlistentry>
    <term>
      <emphasis remap='I'>axis_count_return</emphasis>
    </term>
    <listitem>
      <para>
Returns the number of axes reported in each of the positions returned.
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XGetDeviceMotionEvents' xrefstyle='select: title'/>
returns all positions in the device's motion history buffer
that fall between the specified start and stop times inclusive.
If the start time is in the future or is later than the stop time,
no positions are returned.
</para>
<para>
<!-- .LP -->
The return type for this function is an
<function>XDeviceTimeCoord</function>
structure, which is defined as follows:
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<literallayout class="monospaced">
<!-- .TA .5i -->
<!-- .ta .5i -->
typedef struct {
     Time time;
     unsigned int *data;
} XDeviceTimeCoord;
</literallayout>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
The data member is a pointer to an array of data items.
Each item is of type int, and there is one data item
per axis of motion reported by the device.
The number of axes reported by the device is returned in the axis_count variable.
</para>
<para>
<!-- .LP -->
The value of the data items depends on the mode of the device. 
The mode is returned in the mode variable.  If the 
mode is
<function>Absolute ,</function>
the data items are the raw values generated by the device.
These may be scaled by the client program using the
maximum values that the device can generate for each axis of motion
that it reports.  The maximum value for each axis is reported in
the max_val member of the
<function>XAxisInfo</function>
structure, which is part of the information returned by the
<xref linkend='XListInputDevices' xrefstyle='select: title'/>
request.
</para>
<para>
<!-- .LP -->
If the mode is
<function>Relative ,</function>
the data items are the relative values generated by the device.
The client program must choose an initial
position for the device and maintain a current position by 
accumulating these relative values.
</para>
<para>
<!-- .LP -->
Consecutive calls to
<xref linkend='XGetDeviceMotionEvents' xrefstyle='select: title'/>
can return data of different modes, that is, if
some client program has changed the mode of the device via an
<xref linkend='XSetDeviceMode' xrefstyle='select: title'/>
request.
</para>
<para>
<!-- .LP -->
<xref linkend='XGetDeviceMotionEvents' xrefstyle='select: title'/>
can generate
<function>BadDevice</function>
and
<function>BadMatch</function>
errors.
<!-- .sp -->
</para>
<para>
<!-- .LP -->
To free the data returned by
<function>XGetDeviceMotionEvents ,</function>
use
<function>XFreeDeviceMotionEvents .</function>
</para>
<para>
<!-- .LP -->
<!-- .sM -->
<funcsynopsis id='XFreeDeviceMotionEvents'>
<funcprototype>
  <funcdef>void <function> XFreeDeviceMotionEvents</function></funcdef>
  <paramdef>XDeviceTimeCoord<parameter> *events</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<!-- .FN -->
<variablelist>
  <varlistentry>
    <term>
      <emphasis remap='I'>events</emphasis>
    </term>
    <listitem>
      <para>
Specifies the pointer to the
<function>XDeviceTimeCoord</function>
array returned by a previous call to
<function>XGetDeviceMotionEvents .</function>
    </para>
  </listitem>
  </varlistentry>
</variablelist>
</para>
<para>
<!-- .LP -->
<!-- .eM -->
<xref linkend='XFreeDeviceMotionEvents' xrefstyle='select: title'/>
frees the specified array of motion information.
<!-- .\" -->
<!-- .\" -->
<!-- .\"  Appendicies -->
<!-- .\" -->
<!-- .\" -->
<!-- .bp -->
<!-- .ds Ch ~ -->
<!-- .sp 1 -->
<!-- .ce 3 -->
<function>Appendix A</function>
<!-- .XS -->
<!-- (SN Appendix A -->
<!-- .XE -->
</para>
<para>
<!-- .LP -->
The following information is contained in the <function>&lt;X11/extensions/XInput.h&gt;</function>
and <function>&lt;X11/extensions/XI.h&gt;</function> header files:
<literallayout class="monospaced">
<!-- .cs CW 20 -->

<!-- .ps 8 -->
/* Definitions used by the library and client */

#ifndef _XINPUT_H_
#define _XINPUT_H_

#ifndef _XLIB_H_
#include &lt;X11/Xlib.h&gt;
#endif

#ifndef _XI_H_
#include "XI.h"
#endif

#define _deviceKeyPress          0
#define _deviceKeyRelease     1

#define _deviceButtonPress     0
#define _deviceButtonRelease     1

#define _deviceMotionNotify     0

#define _deviceFocusIn          0
#define _deviceFocusOut          1

#define _proximityIn          0
#define _proximityOut          1

#define _deviceStateNotify     0
#define _deviceMappingNotify     1
#define _changeDeviceNotify     2

#define FindTypeAndClass(d, type, class, classid, offset) \
    { int i; XInputClassInfo *ip; \
    type = 0; class = 0; \
    for (i=0, ip= ((XDevice *) d)-&gt;classes; \
      i&lt; ((XDevice *) d)-&gt;num_classes; \
      i++, ip++) \
     if (ip-&gt;input_class == classid) \
         {type =  ip-&gt;event_type_base + offset; \
          class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | type;}}

#define DeviceKeyPress(d, type, class) \
    FindTypeAndClass(d, type, class, KeyClass, _deviceKeyPress)

#define DeviceKeyRelease(d, type, class) \
    FindTypeAndClass(d, type, class, KeyClass, _deviceKeyRelease)

#define DeviceButtonPress(d, type, class) \
    FindTypeAndClass(d, type, class, ButtonClass, _deviceButtonPress)

#define DeviceButtonRelease(d, type, class) \
    FindTypeAndClass(d, type, class, ButtonClass, _deviceButtonRelease)

#define DeviceMotionNotify(d, type, class) \
    FindTypeAndClass(d, type, class, ValuatorClass, _deviceMotionNotify)

#define DeviceFocusIn(d, type, class) \
    FindTypeAndClass(d, type, class, FocusClass, _deviceFocusIn)

#define DeviceFocusOut(d, type, class) \
    FindTypeAndClass(d, type, class, FocusClass, _deviceFocusOut)

#define ProximityIn(d, type, class) \
    FindTypeAndClass(d, type, class, ProximityClass, _proximityIn)

#define ProximityOut(d, type, class) \
    FindTypeAndClass(d, type, class, ProximityClass, _proximityOut)

#define DeviceStateNotify(d, type, class) \
    FindTypeAndClass(d, type, class, OtherClass, _deviceStateNotify)

#define DeviceMappingNotify(d, type, class) \
    FindTypeAndClass(d, type, class, OtherClass, _deviceMappingNotify)

#define ChangeDeviceNotify(d, type, class) \
    FindTypeAndClass(d, type, class, OtherClass, _changeDeviceNotify)

#define DevicePointerMotionHint(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _devicePointerMotionHint;}

#define DeviceButton1Motion(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButton1Motion;}

#define DeviceButton2Motion(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButton2Motion;}

#define DeviceButton3Motion(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButton3Motion;}

#define DeviceButton4Motion(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButton4Motion;}

#define DeviceButton5Motion(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButton5Motion;}

#define DeviceButtonMotion(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButtonMotion;}

#define DeviceOwnerGrabButton(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceOwnerGrabButton;}

#define DeviceButtonPressGrab(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _deviceButtonGrab;}

#define NoExtensionEvent(d, type, class) \
    { class =  ((XDevice *) d)-&gt;device_id &lt;&lt; 8 | _noExtensionEvent;}

#define BadDevice(dpy, error) _xibaddevice(dpy, &amp;error)

#define BadClass(dpy, error) _xibadclass(dpy, &amp;error)

#define BadEvent(dpy, error) _xibadevent(dpy, &amp;error)

#define BadMode(dpy, error) _xibadmode(dpy, &amp;error)

#define DeviceBusy(dpy, error) _xidevicebusy(dpy, &amp;error)

/***************************************************************
 *
 * DeviceKey events.  These events are sent by input devices that
 * support input class Keys.
 * The location of the X pointer is reported in the coordinate
 * fields of the x,y and x_root,y_root fields.
 *
 */

typedef struct 
    {
    int            type;         /* of event */
    unsigned long  serial;       /* # of last request processed */
    Bool           send_event;   /* true if from SendEvent request */
    Display        *display;     /* Display the event was read from */
    Window         window;       /* "event" window reported relative to */
    XID            deviceid;
    Window         root;         /* root window event occurred on */
    Window         subwindow;    /* child window */
    Time           time;         /* milliseconds */
    int            x, y;         /* x, y coordinates in event window */
    int            x_root;       /* coordinates relative to root */
    int            y_root;       /* coordinates relative to root */
    unsigned int   state;        /* key or button mask */
    unsigned int   keycode;      /* detail */
    Bool           same_screen;  /* same screen flag */
    unsigned int   device_state; /* device key or button mask */
    unsigned char  axes_count;
    unsigned char  first_axis;
    int            axis_data[6];
    } XDeviceKeyEvent;

typedef XDeviceKeyEvent XDeviceKeyPressedEvent;
typedef XDeviceKeyEvent XDeviceKeyReleasedEvent;

/*******************************************************************
 *
 * DeviceButton events.  These events are sent by extension devices
 * that support input class Buttons.
 *
 */

typedef struct {
    int           type;         /* of event */
    unsigned long serial;       /* # of last request processed by server */
    Bool          send_event;   /* true if from a SendEvent request */
    Display       *display;     /* Display the event was read from */
    Window        window;       /* "event" window reported relative to */
    XID           deviceid;
    Window        root;         /* root window that the event occurred on */
    Window        subwindow;    /* child window */
    Time          time;         /* milliseconds */
    int           x, y;         /* x, y coordinates in event window */
    int           x_root;       /* coordinates relative to root */
    int           y_root;       /* coordinates relative to root */
    unsigned int  state;        /* key or button mask */
    unsigned int  button;       /* detail */
    Bool          same_screen;  /* same screen flag */
    unsigned int  device_state; /* device key or button mask */
    unsigned char axes_count;
    unsigned char first_axis;
    int           axis_data[6];
    } XDeviceButtonEvent;

typedef XDeviceButtonEvent XDeviceButtonPressedEvent;
typedef XDeviceButtonEvent XDeviceButtonReleasedEvent;

/*******************************************************************
 *
 * DeviceMotionNotify event.  These events are sent by extension devices
 * that support input class Valuators.
 *
 */

typedef struct 
    {
    int           type;        /* of event */
    unsigned long serial;      /* # of last request processed by server */
    Bool          send_event;  /* true if from a SendEvent request */
    Display       *display;    /* Display the event was read from */
    Window        window;      /* "event" window reported relative to */
    XID           deviceid;
    Window        root;        /* root window that the event occurred on */
    Window        subwindow;   /* child window */
    Time          time;        /* milliseconds */
    int           x, y;        /* x, y coordinates in event window */
    int           x_root;      /* coordinates relative to root */
    int           y_root;      /* coordinates relative to root */
    unsigned int  state;       /* key or button mask */
    char          is_hint;     /* detail */
    Bool          same_screen; /* same screen flag */
    unsigned int  device_state; /* device key or button mask */
    unsigned char axes_count;
    unsigned char first_axis;
    int           axis_data[6];
    } XDeviceMotionEvent;

/*******************************************************************
 *
 * DeviceFocusChange events.  These events are sent when the focus
 * of an extension device that can be focused is changed.
 *
 */

typedef struct 
    {
    int           type;       /* of event */
    unsigned long serial;     /* # of last request processed by server */
    Bool          send_event; /* true if from a SendEvent request */
    Display       *display;   /* Display the event was read from */
    Window        window;     /* "event" window reported relative to */
    XID           deviceid;
    int           mode;       /* NotifyNormal, NotifyGrab, NotifyUngrab */
    int           detail;
     /*
      * NotifyAncestor, NotifyVirtual, NotifyInferior, 
      * NotifyNonLinear,NotifyNonLinearVirtual, NotifyPointer,
      * NotifyPointerRoot, NotifyDetailNone 
      */
    Time                time;
    } XDeviceFocusChangeEvent;

typedef XDeviceFocusChangeEvent XDeviceFocusInEvent;
typedef XDeviceFocusChangeEvent XDeviceFocusOutEvent;

/*******************************************************************
 *
 * ProximityNotify events.  These events are sent by those absolute
 * positioning devices that are capable of generating proximity information.
 *
 */

typedef struct 
    {
    int             type;      /* ProximityIn or ProximityOut */        
    unsigned long   serial;    /* # of last request processed by server */
    Bool            send_event; /* true if this came from a SendEvent request */
    Display         *display;  /* Display the event was read from */
    Window          window;      
    XID                 deviceid;
    Window          root;            
    Window          subwindow;      
    Time            time;            
    int             x, y;            
    int             x_root, y_root;  
    unsigned int    state;           
    Bool            same_screen;     
    unsigned int    device_state; /* device key or button mask */
    unsigned char   axes_count;
    unsigned char   first_axis;
    int             axis_data[6];
    } XProximityNotifyEvent;
typedef XProximityNotifyEvent XProximityInEvent;
typedef XProximityNotifyEvent XProximityOutEvent;

/*******************************************************************
 *
 * DeviceStateNotify events are generated on EnterWindow and FocusIn 
 * for those clients who have selected DeviceState.
 *
 */

typedef struct
    {
    unsigned char     class;
    unsigned char     length;
    } XInputClass;

typedef struct {
    int           type;
    unsigned long serial;       /* # of last request processed by server */
    Bool          send_event;   /* true if this came from a SendEvent request */
    Display       *display;     /* Display the event was read from */
    Window        window;
    XID           deviceid;
    Time          time;
    int           num_classes;
    char       data[64];
} XDeviceStateNotifyEvent;     

typedef struct {
    unsigned char     class;
    unsigned char     length;
    unsigned char     num_valuators;
    unsigned char     mode;
    int                  valuators[6];
} XValuatorStatus;

typedef struct {
    unsigned char     class;
    unsigned char     length;
    short          num_keys;
    char             keys[32];
} XKeyStatus;

typedef struct {
    unsigned char     class;
    unsigned char     length;
    short          num_buttons;
    char             buttons[32];
} XButtonStatus;

/*******************************************************************
 *
 * DeviceMappingNotify event.  This event is sent when the key mapping,
 * modifier mapping, or button mapping of an extension device is changed.
 *
 */

typedef struct {
    int           type;
    unsigned long serial;       /* # of last request processed by server */
    Bool          send_event;   /* true if this came from a SendEvent request */
    Display       *display;     /* Display the event was read from */
    Window        window;       /* unused */
    XID           deviceid;
    Time          time;
    int           request;      /* one of MappingModifier, MappingKeyboard,
                                    MappingPointer */
    int           first_keycode;/* first keycode */
    int           count;        /* defines range of change w. first_keycode*/
} XDeviceMappingEvent;

/*******************************************************************
 *
 * ChangeDeviceNotify event.  This event is sent when an 
 * XChangeKeyboard or XChangePointer request is made.
 *
 */

typedef struct {
    int           type;
    unsigned long serial;       /* # of last request processed by server */
    Bool          send_event;   /* true if this came from a SendEvent request */
    Display       *display;     /* Display the event was read from */
    Window        window;       /* unused */
    XID           deviceid;
    Time          time;
    int           request;      /* NewPointer or NewKeyboard */
} XChangeDeviceNotifyEvent;

/*******************************************************************
 *
 * Control structures for input devices that support input class
 * Feedback.  These are used by the XGetFeedbackControl and 
 * XChangeFeedbackControl functions.
 *
 */

typedef struct {
     XID            class;
     int            length;
     XID            id;
} XFeedbackState;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     click;
    int     percent;
    int     pitch;
    int     duration;
    int     led_mask;
    int     global_auto_repeat;
    char    auto_repeats[32];
} XKbdFeedbackState;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     accelNum;
    int     accelDenom;
    int     threshold;
} XPtrFeedbackState;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     resolution;
    int     minVal;
    int     maxVal;
} XIntegerFeedbackState;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     max_symbols;
    int     num_syms_supported;
    KeySym  *syms_supported;
} XStringFeedbackState;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     percent;
    int     pitch;
    int     duration;
} XBellFeedbackState;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     led_values;
    int     led_mask;
} XLedFeedbackState;

typedef struct {
     XID            class;
     int            length;
     XID         id;
} XFeedbackControl;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     accelNum;
    int     accelDenom;
    int     threshold;
} XPtrFeedbackControl;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     click;
    int     percent;
    int     pitch;
    int     duration;
    int     led_mask;
    int     led_value;
    int     key;
    int     auto_repeat_mode;
} XKbdFeedbackControl;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     num_keysyms;
    KeySym  *syms_to_display;
} XStringFeedbackControl;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     int_to_display;
} XIntegerFeedbackControl;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     percent;
    int     pitch;
    int     duration;
} XBellFeedbackControl;

typedef struct {
    XID     class;
    int     length;
    XID     id;
    int     led_mask;
    int     led_values;
} XLedFeedbackControl;

/*******************************************************************
 *
 * Device control structures.
 *
 */

typedef struct {
     XID            control;
     int            length;
} XDeviceControl;

typedef struct {
     XID            control;
     int            length;
     int            first_valuator;
     int            num_valuators;
     int            *resolutions;
} XDeviceResolutionControl;

typedef struct {
     XID            control;
     int            length;
     int            num_valuators;
     int            *resolutions;
     int            *min_resolutions;
     int            *max_resolutions;
} XDeviceResolutionState;

/*******************************************************************
 *
 * An array of XDeviceList structures is returned by the 
 * XListInputDevices function.  Each entry contains information
 * about one input device.  Among that information is an array of 
 * pointers to structures that describe the characteristics of 
 * the input device.
 *
 */

typedef struct _XAnyClassinfo *XAnyClassPtr;

typedef struct _XAnyClassinfo {
    XID      class;
    int      length;
    } XAnyClassInfo;

typedef struct _XDeviceInfo *XDeviceInfoPtr;

typedef struct _XDeviceInfo
    {
    XID                 id;        
    Atom                type;
    char                *name;
    int                 num_classes;
    int                 use;
    XAnyClassPtr      inputclassinfo;
    } XDeviceInfo;

typedef struct _XKeyInfo *XKeyInfoPtr;

typedef struct _XKeyInfo
    {
    XID               class;
    int               length;
    unsigned short      min_keycode;
    unsigned short      max_keycode;
    unsigned short      num_keys;
    } XKeyInfo;

typedef struct _XButtonInfo *XButtonInfoPtr;

typedef struct _XButtonInfo {
    XID          class;
    int          length;
    short      num_buttons;
    } XButtonInfo;

typedef struct _XAxisInfo *XAxisInfoPtr;

typedef struct _XAxisInfo {
    int      resolution;
    int      min_value;
    int      max_value;
    } XAxisInfo;

typedef struct _XValuatorInfo *XValuatorInfoPtr;

typedef struct     _XValuatorInfo
    {
    XID               class;
    int               length;
    unsigned char       num_axes;
    unsigned char       mode;
    unsigned long       motion_buffer;
    XAxisInfoPtr        axes;
    } XValuatorInfo;


/*******************************************************************
 *
 * An XDevice structure is returned by the XOpenDevice function.  
 * It contains an array of pointers to XInputClassInfo structures.
 * Each contains information about a class of input supported by the
 * device, including a pointer to an array of data for each type of event
 * the device reports.
 *
 */


typedef struct {
        unsigned char   input_class;
        unsigned char   event_type_base;
} XInputClassInfo;

typedef struct {
        XID                    device_id;
        int                    num_classes;
        XInputClassInfo        *classes;
} XDevice;


/*******************************************************************
 *
 * The following structure is used to return information for the 
 * XGetSelectedExtensionEvents function.
 *
 */

typedef struct {
        XEventClass     event_type;
        XID             device;
} XEventList;

/*******************************************************************
 *
 * The following structure is used to return motion history data from 
 * an input device that supports the input class Valuators.
 * This information is returned by the XGetDeviceMotionEvents function.
 *
 */

typedef struct {
        Time   time;
        int    *data;
} XDeviceTimeCoord;


/*******************************************************************
 *
 * Device state structure.
 * This is returned by the XQueryDeviceState request.
 *
 */

typedef struct {
        XID          device_id;
        int          num_classes;
        XInputClass     *data;
} XDeviceState;

/*******************************************************************
 *
 * Note that the mode field is a bitfield that reports the Proximity
 * status of the device as well as the mode.  The mode field should
 * be OR'd with the mask DeviceMode and compared with the values
 * Absolute and Relative to determine the mode, and should be OR'd
 * with the mask ProximityState and compared with the values InProximity
 * and OutOfProximity to determine the proximity state.
 *
 */

typedef struct {
    unsigned char     class;
    unsigned char     length;
    unsigned char     num_valuators;
    unsigned char     mode;
    int                  *valuators;
} XValuatorState;

typedef struct {
    unsigned char     class;
    unsigned char     length;
    short          num_keys;
    char             keys[32];
} XKeyState;

typedef struct {
    unsigned char     class;
    unsigned char     length;
    short          num_buttons;
    char             buttons[32];
} XButtonState;

/*******************************************************************
 *
 * Function definitions.
 *
 */

_XFUNCPROTOBEGIN

extern int     XChangeKeyboardDevice(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */
#endif
);

extern int     XChangePointerDevice(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int               /* xaxis */,
    int               /* yaxis */
#endif
);

extern int     XGrabDevice(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    Window          /* grab_window */,
    Bool          /* ownerEvents */,
    int               /* event count */,
    XEventClass*     /* event_list */,
    int               /* this_device_mode */,
    int               /* other_devices_mode */,
    Time          /* time */
#endif
);

extern int     XUngrabDevice(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    Time           /* time */
#endif
);

extern int     XGrabDeviceKey(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned int     /* key */,
    unsigned int     /* modifiers */,
    XDevice*          /* modifier_device */,
    Window          /* grab_window */,
    Bool          /* owner_events */,
    unsigned int     /* event_count */,
    XEventClass*     /* event_list */,
    int               /* this_device_mode */,
    int               /* other_devices_mode */
#endif
);

extern int     XUngrabDeviceKey(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned int     /* key */,
    unsigned int     /* modifiers */,
    XDevice*          /* modifier_dev */,
    Window          /* grab_window */
#endif
);

extern int     XGrabDeviceButton(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned int     /* button */,
    unsigned int     /* modifiers */,
    XDevice*          /* modifier_device */,
    Window          /* grab_window */,
    Bool          /* owner_events */,
    unsigned int     /* event_count */,
    XEventClass*     /* event_list */,
    int               /* this_device_mode */,
    int               /* other_devices_mode */
#endif
);

extern int     XUngrabDeviceButton(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned int     /* button */,
    unsigned int     /* modifiers */,
    XDevice*          /* modifier_dev */,
    Window          /* grab_window */
#endif
);

extern int     XAllowDeviceEvents(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int               /* event_mode */,
    Time          /* time */
#endif
);

extern int     XGetDeviceFocus(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    Window*          /* focus */,
    int*          /* revert_to */,
    Time*          /* time */
#endif
);

extern int     XSetDeviceFocus(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    Window          /* focus */,
    int               /* revert_to */,
    Time          /* time */
#endif
);

extern XFeedbackState     *XGetFeedbackControl(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int*          /* num_feedbacks */
#endif
);

extern int     XFreeFeedbackList(
#if NeedFunctionPrototypes
    XFeedbackState*     /* list */
#endif
);

extern int     XChangeFeedbackControl(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned long     /* mask */,
    XFeedbackControl*     /* f */
#endif
);

extern int     XDeviceBell(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    XID               /* feedbackclass */,
    XID               /* feedbackid */,
    int               /* percent */
#endif
);

extern KeySym     *XGetDeviceKeyMapping(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
#if NeedWidePrototypes
    unsigned int     /* first */,
#else
    KeyCode          /* first */,
#endif
    int               /* keycount */,
    int*          /* syms_per_code */
#endif
);

extern int     XChangeDeviceKeyMapping(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int               /* first */,
    int               /* syms_per_code */,
    KeySym*          /* keysyms */,
    int               /* count */
#endif
);

extern XModifierKeymap     *XGetDeviceModifierMapping(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */
#endif
);

extern int     XSetDeviceModifierMapping(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    XModifierKeymap*     /* modmap */
#endif
);

extern int     XSetDeviceButtonMapping(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned char*     /* map[] */,
    int               /* nmap */
#endif
);

extern int     XGetDeviceButtonMapping(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    unsigned char*     /* map[] */,
    unsigned int     /* nmap */
#endif
);

extern XDeviceState     *XQueryDeviceState(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */
#endif
);

extern int     XFreeDeviceState(
#if NeedFunctionPrototypes
    XDeviceState*     /* list */
#endif
);

extern XExtensionVersion *XGetExtensionVersion(
#if NeedFunctionPrototypes
    Display*          /* display */,
    _Xconst char*     /* name */
#endif
);

extern XDeviceInfo     *XListInputDevices(
#if NeedFunctionPrototypes
    Display*          /* display */,
    int*          /* ndevices */
#endif
);

extern int     XFreeDeviceList(
#if NeedFunctionPrototypes
    XDeviceInfo*     /* list */
#endif
);

extern XDevice     *XOpenDevice(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XID               /* id */
#endif
);

extern int     XCloseDevice(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */
#endif
);

extern int     XSetDeviceMode(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int               /* mode */
#endif
);

extern int     XSetDeviceValuators(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int*          /* valuators */,
    int               /* first_valuator */,
    int               /* num_valuators */
#endif
);

extern XDeviceControl     *XGetDeviceControl(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int               /* control */
#endif
);

extern int     XChangeDeviceControl(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    int               /* control */,
    XDeviceControl*     /* d */
#endif
);

extern int     XSelectExtensionEvent(
#if NeedFunctionPrototypes
    Display*          /* display */,
    Window          /* w */,
    XEventClass*     /* event_list */,
    int               /* count */
#endif
);

extern int     XGetSelectedExtensionEvents(
#if NeedFunctionPrototypes
    Display*          /* display */,
    Window          /* w */,
    int*          /* this_client_count */,
    XEventClass**     /* this_client_list */,
    int*          /* all_clients_count */,
    XEventClass**     /* all_clients_list */
#endif
);

extern int     XChangeDeviceDontPropagateList(
#if NeedFunctionPrototypes
    Display*          /* display */,
    Window          /* window */,
    int               /* count */,
    XEventClass*     /* events */,
    int               /* mode */
#endif
);

extern XEventClass     *XGetDeviceDontPropagateList(
#if NeedFunctionPrototypes
    Display*          /* display */,
    Window          /* window */,
    int*          /* count */
#endif
);

extern Status     XSendExtensionEvent(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    Window          /* dest */,
    Bool          /* prop */,
    int               /* count */,
    XEventClass*     /* list */,
    XEvent*          /* event */
#endif
);

extern XDeviceTimeCoord     *XGetDeviceMotionEvents(
#if NeedFunctionPrototypes
    Display*          /* display */,
    XDevice*          /* device */,
    Time          /* start */,
    Time          /* stop */,
    int*          /* nEvents */,
    int*          /* mode */,
    int*          /* axis_count */
#endif
);

extern int     XFreeDeviceMotionEvents(
#if NeedFunctionPrototypes
    XDeviceTimeCoord*     /* events */
#endif
);

extern int     XFreeDeviceControl(
#if NeedFunctionPrototypes
    XDeviceControl*     /* control */
#endif
);

_XFUNCPROTOEND

#endif /* _XINPUT_H_ */

/* Definitions used by the server, library and client */

#ifndef _XI_H_

#define _XI_H_

#define sz_xGetExtensionVersionReq          8
#define sz_xGetExtensionVersionReply          32
#define sz_xListInputDevicesReq               4
#define sz_xListInputDevicesReply          32
#define sz_xOpenDeviceReq               8
#define sz_xOpenDeviceReply               32
#define sz_xCloseDeviceReq               8
#define sz_xSetDeviceModeReq               8
#define sz_xSetDeviceModeReply               32
#define sz_xSelectExtensionEventReq          12
#define sz_xGetSelectedExtensionEventsReq     8
#define sz_xGetSelectedExtensionEventsReply     32
#define sz_xChangeDeviceDontPropagateListReq     12
#define sz_xGetDeviceDontPropagateListReq     8
#define sz_xGetDeviceDontPropagateListReply     32
#define sz_xGetDeviceMotionEventsReq          16
#define sz_xGetDeviceMotionEventsReply          32
#define sz_xChangeKeyboardDeviceReq          8
#define sz_xChangeKeyboardDeviceReply          32
#define sz_xChangePointerDeviceReq          8
#define sz_xChangePointerDeviceReply          32
#define sz_xGrabDeviceReq               20
#define sz_xGrabDeviceReply               32
#define sz_xUngrabDeviceReq               12
#define sz_xGrabDeviceKeyReq               20
#define sz_xGrabDeviceKeyReply               32
#define sz_xUngrabDeviceKeyReq               16
#define sz_xGrabDeviceButtonReq               20
#define sz_xGrabDeviceButtonReply          32
#define sz_xUngrabDeviceButtonReq          16
#define sz_xAllowDeviceEventsReq          12
#define sz_xGetDeviceFocusReq               8
#define sz_xGetDeviceFocusReply               32
#define sz_xSetDeviceFocusReq               16
#define sz_xGetFeedbackControlReq          8
#define sz_xGetFeedbackControlReply          32
#define sz_xChangeFeedbackControlReq          12
#define sz_xGetDeviceKeyMappingReq          8
#define sz_xGetDeviceKeyMappingReply          32
#define sz_xChangeDeviceKeyMappingReq          8
#define sz_xGetDeviceModifierMappingReq          8
#define sz_xSetDeviceModifierMappingReq          8
#define sz_xSetDeviceModifierMappingReply     32
#define sz_xGetDeviceButtonMappingReq          8
#define sz_xGetDeviceButtonMappingReply          32
#define sz_xSetDeviceButtonMappingReq          8
#define sz_xSetDeviceButtonMappingReply          32
#define sz_xQueryDeviceStateReq               8
#define sz_xQueryDeviceStateReply          32
#define sz_xSendExtensionEventReq          16
#define sz_xDeviceBellReq               8
#define sz_xSetDeviceValuatorsReq          8
#define sz_xSetDeviceValuatorsReply          32
#define sz_xGetDeviceControlReq               8
#define sz_xGetDeviceControlReply          32
#define sz_xChangeDeviceControlReq          8
#define sz_xChangeDeviceControlReply          32

#define INAME                "XInputExtension"

#define XI_KEYBOARD     "KEYBOARD"
#define XI_MOUSE     "MOUSE"
#define XI_TABLET     "TABLET"
#define XI_TOUCHSCREEN     "TOUCHSCREEN"
#define XI_TOUCHPAD     "TOUCHPAD"
#define XI_BARCODE     "BARCODE"
#define XI_BUTTONBOX     "BUTTONBOX"
#define XI_KNOB_BOX     "KNOB_BOX"
#define XI_ONE_KNOB     "ONE_KNOB"
#define XI_NINE_KNOB     "NINE_KNOB"
#define XI_TRACKBALL     "TRACKBALL"
#define XI_QUADRATURE     "QUADRATURE"
#define XI_ID_MODULE     "ID_MODULE"
#define XI_SPACEBALL     "SPACEBALL"
#define XI_DATAGLOVE     "DATAGLOVE"
#define XI_EYETRACKER     "EYETRACKER"
#define XI_CURSORKEYS     "CURSORKEYS"
#define XI_FOOTMOUSE     "FOOTMOUSE"

#define Dont_Check               0
#define XInput_Initial_Release          1
#define XInput_Add_XDeviceBell          2
#define XInput_Add_XSetDeviceValuators     3
#define XInput_Add_XChangeDeviceControl     4

#define XI_Absent          0
#define XI_Present          1

#define XI_Initial_Release_Major          1
#define XI_Initial_Release_Minor          0

#define XI_Add_XDeviceBell_Major          1
#define XI_Add_XDeviceBell_Minor          1

#define XI_Add_XSetDeviceValuators_Major     1
#define XI_Add_XSetDeviceValuators_Minor     2

#define XI_Add_XChangeDeviceControl_Major     1
#define XI_Add_XChangeDeviceControl_Minor     3

#define DEVICE_RESOLUTION     1

#define NoSuchExtension          1

#define COUNT               0
#define CREATE               1

#define NewPointer          0
#define NewKeyboard          1

#define XPOINTER          0
#define XKEYBOARD          1

#define UseXKeyboard          0xFF

#define IsXPointer          0
#define IsXKeyboard          1
#define IsXExtensionDevice     2

#define AsyncThisDevice          0
#define SyncThisDevice          1
#define ReplayThisDevice     2
#define AsyncOtherDevices     3
#define AsyncAll          4
#define SyncAll               5

#define FollowKeyboard           3
#define RevertToFollowKeyboard      3

#define DvAccelNum              (1L &lt;&lt; 0)
#define DvAccelDenom            (1L &lt;&lt; 1)
#define DvThreshold             (1L &lt;&lt; 2)

#define DvKeyClickPercent     (1L&lt;&lt;0)
#define DvPercent          (1L&lt;&lt;1)
#define DvPitch               (1L&lt;&lt;2)
#define DvDuration          (1L&lt;&lt;3)
#define DvLed               (1L&lt;&lt;4)
#define DvLedMode          (1L&lt;&lt;5)
#define DvKey               (1L&lt;&lt;6)
#define DvAutoRepeatMode     (1L&lt;&lt;7)

#define DvString                (1L &lt;&lt; 0)

#define DvInteger               (1L &lt;&lt; 0)

#define DeviceMode              (1L &lt;&lt; 0)
#define Relative                0
#define Absolute                1

#define ProximityState          (1L &lt;&lt; 1)
#define InProximity             (0L &lt;&lt; 1)
#define OutOfProximity          (1L &lt;&lt; 1)

#define AddToList               0
#define DeleteFromList          1

#define KeyClass            0
#define ButtonClass            1
#define ValuatorClass            2
#define FeedbackClass            3
#define ProximityClass       4
#define FocusClass            5
#define OtherClass            6

#define KbdFeedbackClass       0
#define PtrFeedbackClass       1
#define StringFeedbackClass       2
#define IntegerFeedbackClass       3
#define LedFeedbackClass       4
#define BellFeedbackClass       5

#define _devicePointerMotionHint 0
#define _deviceButton1Motion      1
#define _deviceButton2Motion      2
#define _deviceButton3Motion      3
#define _deviceButton4Motion      4
#define _deviceButton5Motion      5
#define _deviceButtonMotion      6
#define _deviceButtonGrab      7
#define _deviceOwnerGrabButton      8
#define _noExtensionEvent      9

#define XI_BadDevice     0
#define XI_BadEvent     1
#define XI_BadMode     2
#define XI_DeviceBusy     3
#define XI_BadClass     4

typedef     unsigned long     XEventClass;

/*******************************************************************
 *
 * Extension version structure.
 *
 */

typedef struct {
        int        present;
        short     major_version;
        short     minor_version;
} XExtensionVersion;

#endif /* _XI_H_ */

</literallayout>
<!-- .\" print Table of Contents -->
<!-- .if o .bp \" blank page to make count even -->
<!-- .bp 1 -->
<!-- .af PN i -->
<!-- .PX -->


</para>
</sect3>
</sect2>
</sect1>
</chapter>