MirOS Manual: XCloseDevice(3), XOpenDevice(3)


XOpenDevice(3X11)          X FUNCTIONS          XOpenDevice(3X11)

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 suc-
     cessful, 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 CloseDev-
     ice.

     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 requesting client is the last
     client accessing the device, the server may disable 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 XInputClas-
     sInfo structures. Each element of this array contains an
     event type base for a class of input supported by the speci-
     fied device.  The num_classes field indicates the number of
     elements in the classes array.

XFree86                   Version 4.5.0                         1

XOpenDevice(3X11)          X FUNCTIONS          XOpenDevice(3X11)

     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 sup-
     ported by the device.  Defined types include KeyClass, But-
     tonClass, 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 XSelectExtensionEvent requests.  Currently
     defined macros include DeviceKeyPress, DeviceKeyRelease,
     DeviceButtonPress, DeviceButtonRelese, DeviceMotionNotify,
     DeviceFocusIn, DeviceFocusOut, ProximityIn, ProximityOut,
     DeviceStateNotify, DeviceMappiingNotify, ChangeDeviceNotify,
     DevicePointerMotionHint, DeviceButton1Motion,
     DeviceButton2Motion, DeviceButton3Motion,
     DeviceButton4Motion, DeviceButton5Motion, DeviceButtonMo-
     tion, DeviceOwnerGrabButton, DeviceButtonPressGrab, and
     NoExtensionEvent.

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

     DeviceKeyPress (*device, type, eventclass);

     returns the DeviceKeyPress event type and the eventclass for
     DeviceKeyPress 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 XNex-
     tEvent, 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 specified device to
                 become the X keyboard or X pointer device via
                 the XChangeKeyboardDevice or XChangePointerDev-
                 ice requests.

SEE ALSO

     Programming with Xlib

XFree86                   Version 4.5.0                         2

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