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XGetDeviceControl, XChangeDeviceControl - query and change
input device controls
- 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.
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.
Programming With Xlib
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