'\" t
.\" Title: xlistinputdevices
.\" Author: [FIXME: author] [see http://www.docbook.org/tdg5/en/html/author]
.\" Generator: DocBook XSL Stylesheets vsnapshot
.\" Date: 05/04/2023
.\" Manual: \ \&
.\" Source: \ \&
.\" Language: English
.\"
.TH "XLISTINPUTDEVICES" "3" "05/04/2023" "\ \&" "\ \&"
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.SH "NAME"
XListInputDevices, XFreeDeviceList \- list available input devices
.SH "SYNOPSIS"
.sp
.nf
#include
.fi
.sp
.nf
XDeviceInfo *XListInputDevices( Display *display,
int *ndevices_return);
.fi
.sp
.nf
int XFreeDeviceList( XDeviceInfo *list);
.fi
.sp
.nf
display
Specifies the connection to the X server\&.
.fi
.sp
.nf
ndevices_return
Specifies a pointer to a variable where the number of
available devices can be returned\&.
.fi
.sp
.nf
list
Specifies the list of devices to free\&. The
XFreeDeviceList function frees the list of available
extension input devices\&.
.fi
.SH "DESCRIPTION"
.sp
.if n \{\
.RS 4
.\}
.nf
The XListInputDevices request lists the available input
devices\&. This list includes the core keyboard and any physical
input device currently accessible through the X server, and any
input devices that are not currently accessible through the X
server but could be accessed if requested\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
A master pointer is a virtual pointer device that does not
represent a physical device\&. It is visually represented through
a cursor\&. A master keyboard is a virtual keyboard device that
does not represent a physical device\&. It is virtually
represented through a keyboard focus\&. A master pointer and a
master keyboard are always paired (i\&.e\&. if shift is pressed on
the master keyboard, a pointer click would be a shift\-click)\&.
Multiple master pointer/keyboard pairs can exist\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
X servers supporting the X Input Extension version 2,
XListInputDevices only returns the first master pointer, the
first master keyboard and all slave devices\&. Additional master
devices are not listed\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
Physical devices (so\-called slave devices) are attached to
either a master pointer or a master keyboard, depending on
their capabilities\&. If a slave device generates an event, the
event is also generated by the respective master device\&.
Multiple slave devices can be attached to a single master
device\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
Some server implementations may make all physical input devices
available at the time the server is initialized\&. Others may
wait until requested by a client to access an input device\&. In
the latter case, it is possible that an input device will be
listed as available at one time but not at another\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
For each input device available to the server, the
XListInputDevices request returns an XDeviceInfo structure\&.
That structure contains a pointer to a list of structures, each
of which contains information about one class of input
supported by the device\&. The XDeviceInfo structure is defined
as follows:
typedef struct _XDeviceInfo {
XID id;
Atom type;
char *name;
int num_classes;
int use;
XAnyClassPtr inputclassinfo;
} XDeviceInfo;
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The id is a number in the range 0\-128 that uniquely identifies
the device\&. It is assigned to the device when it is initialized
by the server\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The type field is of type Atom and indicates the nature of the
device\&. The type will correspond to one of the following strings
(defined in the header file XI\&.h):
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
XI_MOUSE XI_TABLET XI_KEYBOARD XI_TOUCHSCREEN XI_TOUCHPAD
XI_BUTTONBOX XI_BARCODE XI_TRACKBALL XI_QUADRATURE XI_ID_MODULE
XI_ONE_KNOB XI_NINE_KNOB XI_KNOB_BOX XI_SPACEBALL XI_DATAGLOVE
XI_EYETRACKER XI_CURSORKEYS XI_FOOTMOUSE XI_JOYSTICK
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
These strings may be used in an XInternAtom request to return
an atom that can be compared with the type field of the
XDeviceInfo structure\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The name field contains a pointer to a null\-terminated string
that serves as identifier of the device\&. This identifier may be
user\-configured or automatically assigned by the server\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The num_classes field is a number in the range 0\-255 that
specifies the number of input classes supported by the device
for which information is returned by ListInputDevices\&. Some
input classes, such as class Focus and class Proximity do not
have any information to be returned by ListInputDevices\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
All devices provide an AttachClass\&. This class specifies the
master device a given slave device is attached to\&. For master
devices, the class specifies the respective paired master
device\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The use field specifies how the device is currently being used\&.
If the value is IsXKeyboard, the device is a master keyboard\&.
If the value is IsXPointer, the device is a master pointer\&. If
the value is IsXExtensionPointer, the device is a slave
pointer\&. If the value is IsXExtensionKeyboard, the device is a
slave keyboard\&. If the value is IsXExtensionDevice, the device
is available for use as an extension device\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The inputclassinfo field contains a pointer to the first
input\-class specific data\&. The first two fields are common to
all classes\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The class field is a number in the range 0\-255\&. It uniquely
identifies the class of input for which information is
returned\&. Currently defined classes are KeyClass, ButtonClass,
and ValuatorClass\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The length field is a number in the range 0\- 255\&. It specifies
the number of bytes of data that are contained in this input
class\&. The length includes the class and length fields\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The XKeyInfo structure describes the characteristics of the
keys on the device\&. It is defined as follows:
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
typedef struct _XKeyInfo {
XID class;
int length;
unsigned short min_keycode;
unsigned short max_keycode;
unsigned short num_keys;
} XKeyInfo;
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
min_keycode is of type KEYCODE\&. It specifies the minimum
keycode that the device will report\&. The minimum keycode will
not be smaller than 8\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
max_keycode is of type KEYCODE\&. It specifies the maximum
keycode that the device will report\&. The maximum keycode will
not be larger than 255\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
num_keys specifies the number of keys that the device has\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The XButtonInfo structure defines the characteristics of the
buttons on the device\&. It is defined as follows:
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
typedef struct _XButtonInfo {
XID class;
int length;
short num_buttons;
} XButtonInfo;
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
num_buttons specifies the number of buttons that the device
has\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The XValuatorInfo structure defines the characteristics of the
valuators on the device\&. It is defined as follows:
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
typedef struct _XValuatorInfo {
XID class;
int length;
unsigned char num_axes;
unsigned char mode;
unsigned long motion_buffer;
XAxisInfoPtr axes;
} XValuatorInfo;
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
num_axes contains the number of axes the device supports\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
mode is a constant that has one of the following values:
Absolute or Relative\&. Some devices allow the mode to be changed
dynamically via the SetDeviceMode request\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
motion_buffer_size is a cardinal number that specifies the
number of elements that can be contained in the motion history
buffer for the device\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The axes field contains a pointer to an XAxisInfo structure\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The XAxisInfo structure is defined as follows:
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
typedef struct _XAxisInfo {
int resolution;
int min_value;
int max_value;
} XAxisInfo;
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The resolution contains a number in counts/meter\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The min_val field contains a number that specifies the minimum
value the device reports for this axis\&. For devices whose mode
is Relative, the min_val field will contain 0\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The max_val field contains a number that specifies the maximum
value the device reports for this axis\&. For devices whose mode
is Relative, the max_val field will contain 0\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
The XAttachInfo structure is defined as follows:
typedef struct _XAttachInfo {
int attached;
} XAttachInfo;
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
If the device is a slave device, attached specifies the device
ID of the master device this device is attached to\&. If the
device is not attached to a master device, attached is
Floating\&. If the device is a master device, attached specifies
the device ID of the master device this device is paired with\&.
.fi
.if n \{\
.RE
.\}
.SH "RETURN VALUE"
.sp
.if n \{\
.RS 4
.\}
.nf
XListInputDevices returns a pointer to an array of XDeviceInfo
structs and sets ndevices_return to the number of elements in
that array\&. To free the XDeviceInfo array created by
XListInputDevices, use XFreeDeviceList\&.
.fi
.if n \{\
.RE
.\}
.sp
.if n \{\
.RS 4
.\}
.nf
On error, XListInputDevices returns NULL and ndevices_return is
left unmodified\&.
.fi
.if n \{\
.RE
.\}