XIQUERYDEVICE
XIQUERYDEVICE
NAMESYNOPSIS
DESCRIPTION
DIAGNOSTICS
NAME
XIQueryDevice, XIFreeDeviceInfo − get information about devices.
SYNOPSIS
#include <X11/extensions/XInput2.h>
XIDeviceInfo*
XIQueryDevice( 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.
DESCRIPTION
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.
DIAGNOSTICS
BadDevice
An invalid device was specified. The device does not
exist or is not a pointer device.
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