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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
	   attachment.
	 - 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, XIGestureClass.

	 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 minimum 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 occurred. 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.

	 typedef struct
	 {
	     int	 type;
	     int	 sourceid;
	     int	 num_touches;
	 } XIGestureClassInfo;

	 A device may have zero or one XIGestureClassInfo, denoting
	 touchpad gesture capability on the device. A device with a XIGestureClassInfo
	 may send GestureSwipeBegin, GestureSwipeUpdate, GestureSwipeEnd,
	 GesturePinchBegin, GesturePinchUpdate, GesturePinchEnd.

	 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.

	 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.

				   05/18/2026			XIQUERYDEVICE(3)

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