XGETFEEDBACKCONTROL(3) |  | XGETFEEDBACKCONTROL(3)

# NAME

XGetFeedbackControl, XChangeFeedbackControl - query and change input device feedbacks

# SYNOPSIS

    #include <X11/extensions/XInput.h>

    XFeedbackState *XGetFeedbackControl( Display *display,

                                         XDevice *device,

                                         int *num_feedbacks);

    int XChangeFeedbackControl( Display *display,

                                XDevice *device,

                                Mask mask,

                                XFeedbackControl *control);

    display

           Specifies the connection to the X server.

    device

           Specifies the device whose feedbacks are to be queried

           or modified.

    num_feedbacks

           Specifies an address into which the number of feedbacks

           supported by the device is to be returned.

    mask

           Specifies a mask specific to each type of feedback that

           describes how the feedback is to be modified.

    control

           Specifies the address of an XFeedbackControl structure

           that contains the new values for the feedback.

# DESCRIPTION

    These requests are provided to manipulate those input devices
    that support feedbacks. A BadMatch error will be generated if
    the requested device does not support feedbacks. Whether or not
    a given device supports feedbacks can be determined by
    examining the information returned by the XOpenDevice request.
    For those devices that support feedbacks, XOpenDevice will
    return an XInputClassInfo structure with the input_class field
    equal to the constant FeedbackClass (defined in the file XI.h).

    The XGetFeedbackControl request returns a pointer to a list of
    XFeedbackState structures. Each item in this list describes one
    of the feedbacks supported by the device. The items are
    variable length, so each contains its length to allow traversal
    to the next item in the list.

    The feedback classes that are currently defined are:
    KbdFeedbackClass, PtrFeedbackClass, StringFeedbackClass,
    IntegerFeedbackClass, LedFeedbackClass, and BellFeedbackClass.
    These constants are defined in the file XI.h. An input device
    may support zero or more classes of feedback, and may support
    multiple feedbacks of the same class. Each feedback contains a
    class identifier and an id that is unique within that class for
    that input device. The id is used to identify the feedback when
    making an XChangeFeedbackControl request.

    XGetFeedbackControl can generate a BadDevice or BadMatch error.

    The XChangeFeedbackControl request modifies the values of one
    feedback on the specified device. The feedback is identified by
    the id field of the XFeedbackControl structure that is passed
    with the request. The fields of the feedback that are to be
    modified are identified by the bits of the mask that is passed
    with the request.

    XChangeFeedbackControl can generate a BadDevice, BadMatch, or
    BadValue error.

## Structures

    Each class of feedback is described by a structure specific to
    that class. These structures are defined in the file XInput.h.
    XFeedbackState and XFeedbackControl are generic structures that
    contain three fields that are at the beginning of each class of
    feedback:

    typedef struct {

        XID class;

        int length;

        XID id;
    } XFeedbackState, XFeedbackControl;

    The XKbdFeedbackState structure defines the attributes that are
    returned for feedbacks equivalent to those on the X keyboard.

    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;

    The XPtrFeedbackState structure defines the attributes that are
    returned for feedbacks equivalent to those on the the X
    pointer.

    typedef struct {

        XID class;

        int length;

        XID id;

        int accelNum;

        int accelDenom;

        int threshold;
    } XPtrFeedbackState;

    The XIntegerFeedbackState structure defines attributes that are
    returned for integer feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int resolution;

        int minVal;

        int maxVal;
    } XIntegerFeedbackState;

    The XStringFeedbackState structure defines the attributes that
    are returned for string feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int max_symbols;

        int num_syms_supported;

        KeySym *syms_supported;
    } XStringFeedbackState;

    The XBellFeedbackState structure defines the attributes that
    are returned for bell feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int percent;

        int pitch;

        int duration;
    } XBellFeedbackState;

    The XLedFeedbackState structure defines the attributes that are
    returned for LED feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int led_values;
    } XLedFeedbackState;

    The XPrtFeedbackControl structure defines the attributes that
    can be controlled for pointer feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int accelNum;

        int accelDenom;

        int threshold;
    } XPtrFeedbackControl;

    The XKbdFeedbackControl structure defines the attributes that
    can be controlled for keyboard feedbacks.

    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;

    The XStringFeedbackControl structure defines the attributes
    that can be controlled for string feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int num_keysyms;

        KeySym  *syms_to_display;
    } XStringFeedbackControl;

    The XIntegerFeedbackControl structure defines the attributes
    that can be controlled for integer feedbacks.

    typedef struct {

        XID class;

        int length;

        XID id;

        int int_to_display;
    } XIntegerFeedbackControl;

    The XBellFeedbackControl structure defines the attributes that
    can be controlled for bell feedbacks.

    typedef struct {

        XID     class;

        int     length;

        XID     id;

        int     percent;

        int     pitch;

        int     duration;
    } XBellFeedbackControl;

    The XLedFeedbackControl structure defines the attributes that
    can be controlled for LED feedbacks.

    typedef struct {

        XID     class;

        int     length;

        XID     id;

        int     led_mask;

        int     led_values;
    } XLedFeedbackControl;

# DIAGNOSTICS

    BadDevice

           An invalid device was specified. The specified device

           does not exist or has not been opened by this client via

           XOpenInputDevice. 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 XChangePointerDevice requests.

    BadMatch

           This error may occur if an XGetFeedbackControl request

           was made specifying a device that has no feedbacks, or

           an XChangeFeedbackControl request was made with an

           XFeedbackControl structure that contains an invalid

           feedback type. It may also occur if an invalid

           combination of mask bits is specified ( DvKey but no

           DvAutoRepeatMode for keyboard feedbacks), or if an

           invalid KeySym is specified for a string feedback.

    BadValue

           Some numeric value falls outside the range of values

           accepted by the XChangeFeedbackControl request. Unless a

           specific range is specified for an argument, the full

           range defined by the argument's type is accepted. Any

           argument defined as a set of alternatives can generate

           this error.

05/18/2026 |