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XListInputDevices

NAME

XListInputDevices, XFreeDeviceList - list available input devices

SYNOPSIS

 #include <X11/extensions/XInput.h>
 

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

 int XFreeDeviceList( XDeviceInfo *list);
 

 display
        Specifies the connection to the X server.
 

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

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

DESCRIPTION

 The XListInputDevices request lists the available input
 devices. This list includes the core keyboard and any physical
 input device 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.
 

 A master pointer is a virtual pointer device that does not
 represent a physical device. It is visually represented through
 a cursor. A master keyboard is a virtual keyboard device that
 does not represent a physical device. It is virtually
 representd through a keyboard focus. A master pointer and a
 master keyboard are always paired (i.e. if shift is pressed on
 the master keyboard, a pointer click would be a shift-click).
 Multiple master pointer/keyboard pairs can exist.
 

 X servers supporting the X Input Extension version 2,
 XListInputDevices only returns the first master pointer, the
 first master keyboard and all slave devices. Additional master
 devices are not listed.
 

 Physical devices (so-called slave devices) are attached to
 either a master pointer or a master keyboard, depending on
 their capabilities. If a slave device generates an event, the
 event is also generated by the respective master device.
 Multiple slave devices can be attached to a single master
 device.
 

 Some server implementations may make all physical 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. The type will correspond to one of the following strings
 (defined in the header file XI.h):
 

 XI_MOUSE XI_TABLET XI_KEYBOARD XI_TOUCHSCREEN XI_TOUCHPAD
 XI_BUTTONBOX XI_BARCODE XI_TRACKBALL XI_QUADRATURE XI_ID_MODULE
 XI_ONE_KNOB XI_NINE_KNOB XI_KNOB_BOX XI_SPACEBALL XI_DATAGLOVE
 XI_EYETRACKER XI_CURSORKEYS XI_FOOTMOUSE XI_JOYSTICK
 

 These strings may be used in an XInternAtom request to return
 an atom that can be compared with the type field of the
 XDeviceInfo structure.
 

 The name field contains a pointer to a null-terminated string
 that serves as identifier of the device. This identifier may be
 user-configured or automatically assigned by the server.
 

 The num_classes field is a number in the range 0-255 that
 specifies the 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.
 

 All devices provide an AttachClass. This class specifies the
 master device a given slave device is attached to. For master
 devices, the class specifies the respective paired master
 device.
 

 The use field specifies how the device is currently being used.
 If the value is IsXKeyboard, the device is a master keyboard.
 If the value is IsXPointer, the device is a master pointer. If
 the value is IsXExtensionPointer, the device is a slave
 pointer. If the value is IsXExtensionKeyboard, the device is a
 slave keyboard. 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;
 

 num_buttons specifies the number of buttons that the device
 has.
 

 The XValuatorInfo structure defines the characteristics of the
 valuators on the device. It is defined as follows:
 

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

 num_axes contains the number of axes the device supports.
 

 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.
 

 The XAttachInfo structure is defined as follows:
              typedef struct _XAttachInfo {
              int     attached;
              } XAttachInfo;
 

 If the device is a slave device, attached specifies the device
 ID of the master device this device is attached to. If the
 device is not attached to a master device, attached is
 Floating. If the device is a master device, attached specifies
 the device ID of the master device this device is paired with.
 

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