XGetDeviceControl, XChangeDeviceControl - query and change input device controls
SYNTAX
XDeviceControl *XGetDeviceControl(Display *display, XDevice
*device, int *controlType);
int XChangeDeviceControl(Display *display, XDevice
*device, int controlType, XDeviceControl *control);
ARGUMENTS
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.
