XIQUERYDEVICE(3)														  XIQUERYDEVICE(3)

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, XIScrollClass,
	       XITouchClass

	   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;
	   } XIValuatorClassInfo;

	   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.

	   typedef struct
	   {
	       int	   type;
	       int	   sourceid;
	       int	   number;
	       int	   scroll_type;
	       double	   increment;
	       int	   flags;
	   } XIScrollClassInfo;

	   This class describes scrolling capability on a valuator. For
	   each XIScrollClassInfo, an XIValuatorClassInfo with the same
	   number is present on the device.

	   The number field specifies the valuator number on the physical
	   device that this scroll information applies to. See the
	   respective XIValuatorClassInfo for detailed information on this
	   valuator.

	   The scroll_type field specifies the type of scrolling, either
	   XIScrollTypeVertical or XIScrollTypeHorizontal.

	   The increment specifies the value change considered one unit of
	   scrolling down.

	   The flags field specifies flags that apply to this scrolling
	   information:

	   If XIScrollFlagNoEmulation is set, the server will not
	   emulate legacy button events for valuator changes on this
	   valuator.

	   If XIScrollFlagPreferred is set, this axis is the
	   preferred axis for this scroll type and will be used for
	   the emulation of XI_Motion events when the driver submits
	   legacy scroll button events.

	   typedef struct
	   {
	       int	   type;
	       int	   sourceid;
	       int	   mode;
	       int	   num_touches;
	   } XITouchClassInfo;

	   A device may have zero or one XITouchClassInfo, denoting
	   multi-touch capability on the device. A device with a XITouchClassInfo
	   may send TouchBegin, TouchUpdate, TouchEnd and TouchOwnership events.

	   The mode field is either XIDirectTouch for direct-input touch devices
	   such as touchscreens or XIDependentTouch for indirect input devices such
	   as touchpads. For XIDirectTouch devices, touch events are sent to window
	   at the position the touch occured. For XIDependentTouch devices, touch
	   events are sent to the window at the position of the device's sprite.

	   The num_touches field defines the maximum number of simultaneous touches
	   the device supports. A num_touches of 0 means the maximum number of
	   simultaneous touches is undefined or unspecified. This field should be
	   used as a guide only, devices will lie about their capabilities.

	   A device with an XITouchClassInfo may still send pointer events. The
	   valuators must be defined with the respective XIValuatorClass
	   classes. A valuator may send both pointer and touch-events.

	   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.

								    05/15/2013							  XIQUERYDEVICE(3)