SYNTAX

       XDeviceInfo *XListInputDevices(Display *display, int *ndevices_return);

       int XFreeDeviceList(XDeviceInfo *list);

ARGUMENTS

       display     Specifies the connection to the X server.

       ndevices_return
                   Specifies a pointer to  a  variable  where  the  number  of
                   available devices can be returned.

       list        Specifies the list of devices to free.  The XFreeDeviceList
                   function  frees  the  list  of  available  extension  input
                   devices.

DESCRIPTION

       The  XListInputDevices  request  lists  the  available  extension input
       devices.  This list includes the X pointer and X  keyboard,  any  other
       input  devices  that are currently accessible through the X server, and
       any input devices that are  not  currently  accessible  through  the  X
       server but could be accessed if requested.

       Some server implementations may make all input devices available at the
       time the server is initialized.  Others may wait until requested  by  a
       client  to  access an input device.  In the latter case, it is possible
       that an input device will be listed as available at one time but not at
       another.

       For  each  input  device available to the server, the XListInputDevices
       request returns an XDeviceInfo structure.  That  structure  contains  a
       pointer  to  a  list  of structures, each of which contains information
       about one class of input supported by the device.

       The XDeviceInfo structure is defined as follows:

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

       The id is a number in the range  0-128  that  uniquely  identifies  the
       device.   It  is  assigned  to the device when it is initialized by the
       server.

       The type field is of type Atom and indicates the nature of the  device.

       number of input classes supported by the device for  which  information
       is  returned  by  ListInputDevices.   Some input classes, such as class
       Focus and class Proximity do not have any information to be returned by
       ListInputDevices.

       The use field specifies how the device is currently being used.  If the
       value is IsXKeyboard, the device is currently being used as the X  key-
       board.   If the value is IsXPointer, the device is currently being used
       as the X pointer.  If the value is IsXExtensionDevice,  the  device  is
       available for use as an extension device.

       The  inputclassinfo  field  contains a pointer to the first input-class
       specific data.  The first two fields are common to all classes.

       The class field is a number in the range 0-255.  It uniquely identifies
       the  class  of  input  for  which  information  is returned.  Currently
       defined classes are KeyClass, ButtonClass, and ValuatorClass.

       The length field is a number in the range 0-  255.   It  specifies  the
       number  of  bytes  of data that are contained in this input class.  The
       length includes the class and length fields.

       The XKeyInfo structure describes the characteristics of the keys on the
       device.  It is defined as follows:

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

       min_keycode  is of type KEYCODE.  It specifies the minimum keycode that
       the device will report.  The minimum keycode will not be  smaller  than
       8.

       max_keycode  is of type KEYCODE.  It specifies the maximum keycode that
       the device will report.  The maximum keycode will not  be  larger  than
       255.

       num_keys specifies the number of keys that the device has.

       The XButtonInfo structure defines the characteristics of the buttons on
       the device.  It is defined as follows:

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


       mode  is  a  constant that has one of the following values: Absolute or
       Relative.  Some devices allow the mode to be  changed  dynamically  via
       the SetDeviceMode request.

       motion_buffer_size  is  a  cardinal number that specifies the number of
       elements that can be contained in the motion  history  buffer  for  the
       device.

       The axes field contains a pointer to an XAxisInfo structure.

       The XAxisInfo structure is defined as follows:

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

       The resolution contains a number in counts/meter.

       The  min_val  field  contains a number that specifies the minimum value
       the device reports for this axis.  For devices whose mode is  Relative,
       the min_val field will contain 0.

       The  max_val  field  contains a number that specifies the maximum value
       the device reports for this axis.  For devices whose mode is  Relative,
       the max_val field will contain 0.

       To  free  the  XDeviceInfo  array  created  by  XListInputDevices,  use
       XFreeDeviceList.

DIAGNOSTICS

       none.

SEE ALSO

       Programming with Xlib



X Version 11                      Release 6.6          XListInputDevices(3X11)