XGETDEVICECONTROL

Section: \ \& (3)
Updated: 06/19/2019
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NAME

XGetDeviceControl, XChangeDeviceControl - query and change input device controls

SYNOPSIS

#include <X11/extensions/XInput.h>

XDeviceControl *XGetDeviceControl( Display *display,
                                   XDevice *device,
                                   int *controlType);

int XChangeDeviceControl( Display *display,
                          XDevice *device,
                          int controlType,
                          XDeviceControl *control);

display
       Specifies the connection to the X server.

device
       Specifies the device whose control is to be interrogated
       or modified.

controlType
       Specifies the type of control to be interrogated or
       changed.

control
       Specifies the address of an XDeviceControl structure
       that contains the new values for the Device.

DESCRIPTION

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.

STRUCTURES

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;

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 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.