#include <X11/extensions/XInput2.h>
XIDeviceInfo* XIQueryPointer( Display *display,
int deviceid,
int *ndevices_return);
XIFreeDeviceInfo( XIDeviceInfo *info);
deviceid
Specifies the device to query or XIAllDevices or
XIAllMasterDevices.
display
Specifies the connection to the X server.
ndevices_return
Returns the number of devices returned.
info
A list of device XIDeviceInfo structs to be freed.
The XIQueryDevice returns information about one or more input devices. If the deviceid specifies a device, ndevices_return is 1 and the returned information describes only the requested device. If deviceid is XIAllDevices or XIAllMasterDevices, ndevices_return is the number of devices or master devices, respectively, and the returned information represents all devices or all master devices, respectively.
To free the XIDeviceInfo array returned by XIQueryDevice, use XIFreeDeviceInfo.
For each input device requested, the XIQueryDevice returns an XIDeviceInfo structure. Each structure contains information about the capabilities of one input device available to the server.
typedef struct
{
int deviceid;
char *name;
int use;
int attachment;
Bool enabled;
int num_classes;
XIAnyClassInfo **classes;
} XIDeviceInfo;
The deviceid is the numeric unique id of the device. A deviceid is unique for the life-time of a device but a server may re-use the id once a device has been removed.
The name points to a null-terminated string specifying the identifier of the device.
The use and attachment fields specify the type of the device and the current attachment or pairing. - If use is XIMasterPointer, the device is a master pointer and attachment specifies the deviceid of the paired master keyboard. - If use is XIMasterKeyboard, the device is a master keyboard, and the attachment field specifies the paired master pointer. - If use is XISlavePointer, the device is a slave device and currently attached to the master pointer specified in attachement. - If use is XISlaveKeyboard, the device is a slave device an currently attached to the master keyboard specified in attachment. - If use is XIFloatingSlave, the device is a slave device currently not attached to any master device. The value of the attachment field for floating slave devices is undefined.
The enabled field specifies if the device is currently enabled and can send events. Disabled devices will not send events.
The num_classes field specifies the number of input classes pointed to by classes. The first two fields of all input classes are identical.
typedef struct
{
int type;
int sourceid;
} XIAnyClassInfo;
The type field specifies the type of the input class.
Currently, the following types are defined:
XIKeyClass, XIButtonClass, XIValuatorClass
In the future, additional types may be added. Clients are required to ignore unknown input classes.
The sourceid is the deviceid this class originated from. For master devices, the sourceid is typically the id of the slave device currently sending events. For slave devices, the sourceid is typically the device's id.
A device may have zero or one XIButtonClass, denoting the device's capability to send button events.
typedef struct {
int mask_len;
unsigned char *mask;
} XIButtonState;
typedef struct
{
int type;
int sourceid;
int num_buttons;
Atom *labels;
XIButtonState state;
} XIButtonClassInfo;
The num_buttons field specifies the number of buttons available on this device. A device that has an XIButtonClass must have at least one button.
labels is a list of num_buttons Atoms specifying the button labels for this device. If the label is not None, then the label specifies the type of button in physical device order (i.e. as the buttons are numbered on the physical input device).
The state is the current button state as seen by clients (i.e. after button mapping is applied). The mask_len field specifies the length of mask in bytes. For each button on the device, the respective bit in mask is set if the button is currently logically down.
A device may have zero or one XIKeyClass, denoting the device's capability to send key events.
typedef struct
{
int type;
int sourceid;
int num_keycodes;
int *keycodes;
} XIKeyClassInfo;
The num_keycodes field specifies the number of keycodes available on this device. A device that has an XIKeyClass must have at least one keycode.
keycodes is a list of num_keycodes keycodes the device may send.
A device may have zero or more XIValuatorClass, denoting the device's capability to send coordinates.
typedef struct
{
int type;
int sourceid;
int number;
Atom label;
double min;
double max;
double value;
int resolution;
int mode;
} XIValuatorInfo;
The number field specifies the number of the axis on the physical device.
If the label field is not None, the value of label is an Atom describing the axis.
min and max are the minimum and maximum values allowed on this axis. If both are zero, no minumum or maximum values are set on this device. value is the current value of this axis.
The resolution field specifies the resolution of the device in units/m.
The mode specifies the mode of this axis. If the mode is XIModeAbsolute this axis sends absolute coordinates. If the mode is XIModeRelative, this device sends relative coordinates.
XIQueryDevice can generate a BadDevice error.
XIFreeDeviceInfo frees the information returned by XIQueryDevice.
BadDevice
An invalid device was specified. The device does not
exist or is not a pointer device.