XOpenDevice(3)

NAME

       XOpenDevice, XCloseDevice - open or close an extension input device

SYNTAX

       XDevice *XOpenDevice(Display *display, XID device_id);

       XCloseDevice(Display *display, XDevice *device);

ARGUMENTS

       display     Specifies the connection to the X server.

       device_id   Specifies the id of the device to be opened

       device      Specifies the device to be closed

DESCRIPTION

       The  XOpenDevice  request  makes an input device accessible to a client
       through input extension protocol requests.  If successful, it returns a
       pointer to an XDevice structure.

       The XCloseDevice request makes an input device inaccessible to a client
       through input extension protocol  requests.   Before  terminating,  and
       client that has opened input devices through the input extension should
       close them via CloseDevice.

       When a client makes an XCloseDevice request, any active grabs that  the
       client  has  on the device are released.  Any event selections that the
       client has are deleted, as well as any passive grabs.  If the  request-
       ing client is the last client accessing the device, the server may dis-
       able all access by X to the device.

       XOpenDevice and XCloseDevice can generate a BadDevice error.

STRUCTURES

       The XDevice structure returned by XOpenDevice contains:
       typedef struct {
            XID device_id;
            int num_classes;
            XInputClassInfo *classes;
       } XDevice;

       The classes field is a pointer to an array  of  XInputClassInfo  struc-
       tures.   Each  element  of this array contains an event type base for a
       class of input supported by  the  specified  device.   The  num_classes
       field indicates the number of elements in the classes array.

       The XInputClassInfo structure contains:

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

       The  input_class  field  identifies one class of input supported by the
       device.  Defined types include  KeyClass,  ButtonClass,  ValuatorClass,
       ProximityClass,   FeedbackClass,   FocusClass,   and  OtherClass.   The
       event_type_base identifies the event type of the first  event  in  that
       class.

       The  information  contained in the XInputClassInfo structure is used by
       macros to obtain the event classes that  clients  use  in  making  XSe-
       lectExtensionEvent   requests.    Currently   defined   macros  include
       DeviceKeyPress,  DeviceKeyRelease,  DeviceButtonPress,  DeviceButtonRe-
       lese,  DeviceMotionNotify,  DeviceFocusIn, DeviceFocusOut, ProximityIn,
       ProximityOut, DeviceStateNotify, DeviceMappiingNotify,  ChangeDeviceNo-
       tify,    DevicePointerMotionHint,    DeviceButton1Motion,    DeviceBut-
       ton2Motion,   DeviceButton3Motion,   DeviceButton4Motion,    DeviceBut-
       ton5Motion,  DeviceButtonMotion,  DeviceOwnerGrabButton,  DeviceButton-
       PressGrab, and NoExtensionEvent.

       To obtain the proper event class for a particular device,  one  of  the
       above  macros  is  invoked using the XDevice structure for that device.
       For example,

       DeviceKeyPress (*device, type, eventclass);

       returns the DeviceKeyPress event type and the eventclass for DeviceKey-
       Press events from the specified device.

       This eventclass can then be used in an XSelectExtensionEvent request to
       ask the server to send DeviceKeyPress events from this device.  When  a
       selected  event  is  received  via XNextEvent, the type can be used for
       comparison with the type in the event.

DIAGNOSTICS

       BadDevice   An invalid device was specified.  The specified device does
                   not  exist,  or is the X keyboard or X pointer.  This error
                   may also occur if some other client has caused  the  speci-
                   fied  device  to  become the X keyboard or X pointer device
                   via  the  XChangeKeyboardDevice   or   XChangePointerDevice
                   requests.

SEE ALSO

       Programming with Xlib

X Version 11                      libXi 1.0.2                XOpenDevice(3X11)