These requests are provided to manipulate those input devices
that support device control. A BadMatch error will be generated
if the requested device does not support any device controls.

Valid device control types that can be used with these requests
include the following:

DEVICE_RESOLUTION: Queries or changes the resolution of
valuators on input devices.

The XGetDeviceControl request returns a pointer to an
XDeviceControl structure.

XGetDeviceControl can generate a BadDevice or BadMatch error.

The XChangeDeviceControl request modifies the values of one
control on the specified device. The control is identified by
the id field of the XDeviceControl structure that is passed
with the request.

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

Each control is described by a structure specific to that control.
These structures are defined in the file XInput.h.

XDeviceControl is a generic structure that contains two fields
that are at the beginning of each class of control:

typedef struct {


    XID class;


    int length;
} XDeviceControl;

The XDeviceResolutionState structure defines the information
that is returned for device resolution for devices with
valuators.

typedef struct {


    XID control;


    int length;


    int num_valuators;


    int* resolutions;


    int* min_resolutions;


    int* max_resolutions;
} XDeviceResolutionState;

The XDeviceResolutionControl structure defines the attributes
that can be controlled for keyboard Devices.

typedef struct {


    XID control;


    int length;


    int first_valuator;


    int num_valuators;


    int* resolutions;
} XDeviceResolutionControl;

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 XGetDeviceControl request was


       made specifying a device that has no controls or an


       XChangeDeviceControl request was made with an


       XDeviceControl structure that contains an invalid Device


       type. It may also occur if an invalid combination of


       mask bits is specified ( DvKey but no DvAutoRepeatMode


       for keyboard Devices), or if an invalid KeySym is


       specified for a string Device.

BadValue


       Some numeric value falls outside the range of values


       accepted by the XChangeDeviceControl 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.