1XLISTINPUTDEVICES(3) XLISTINPUTDEVICES(3)
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6 XListInputDevices, XFreeDeviceList - list available input devices
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9 #include <X11/extensions/XInput.h>
10 XDeviceInfo *XListInputDevices( Display *display,
12 int *ndevices_return);
13 int XFreeDeviceList( XDeviceInfo *list);
15 display
17 Specifies the connection to the X server.
18 ndevices_return
20 Specifies a pointer to a variable where the number of
21 available devices can be returned.
22 list
24 Specifies the list of devices to free. The
25 XFreeDeviceList function frees the list of available
26 extension input devices.
27
29 The XListInputDevices request lists the available input
30 devices. This list includes the core keyboard and any physical
31 input device currently accessible through the X server, and any
32 input devices that are not currently accessible through the X
33 server but could be accessed if requested.
34 A master pointer is a virtual pointer device that does not
36 represent a physical device. It is visually represented through
37 a cursor. A master keyboard is a virtual keyboard device that
38 does not represent a physical device. It is virtually
39 represented through a keyboard focus. A master pointer and a
40 master keyboard are always paired (i.e. if shift is pressed on
41 the master keyboard, a pointer click would be a shift-click).
42 Multiple master pointer/keyboard pairs can exist.
43 X servers supporting the X Input Extension version 2,
45 XListInputDevices only returns the first master pointer, the
46 first master keyboard and all slave devices. Additional master
47 devices are not listed.
48 Physical devices (so-called slave devices) are attached to
50 either a master pointer or a master keyboard, depending on
51 their capabilities. If a slave device generates an event, the
52 event is also generated by the respective master device.
53 Multiple slave devices can be attached to a single master
54 device.
55 Some server implementations may make all physical input devices
57 available at the time the server is initialized. Others may
58 wait until requested by a client to access an input device. In
59 the latter case, it is possible that an input device will be
60 listed as available at one time but not at another.
61 For each input device available to the server, the
63 XListInputDevices request returns an XDeviceInfo structure.
64 That structure contains a pointer to a list of structures, each
65 of which contains information about one class of input
66 supported by the device. The XDeviceInfo structure is defined
67 as follows:
68 typedef struct _XDeviceInfo {
69 XID id;
70 Atom type;
71 char *name;
72 int num_classes;
73 int use;
74 XAnyClassPtr inputclassinfo;
75 } XDeviceInfo;
76 The id is a number in the range 0-128 that uniquely identifies
78 the device. It is assigned to the device when it is initialized
79 by the server.
80 The type field is of type Atom and indicates the nature of the
82 device. The type will correspond to one of the following strings
83 (defined in the header file XI.h):
84 XI_MOUSE XI_TABLET XI_KEYBOARD XI_TOUCHSCREEN XI_TOUCHPAD
86 XI_BUTTONBOX XI_BARCODE XI_TRACKBALL XI_QUADRATURE XI_ID_MODULE
87 XI_ONE_KNOB XI_NINE_KNOB XI_KNOB_BOX XI_SPACEBALL XI_DATAGLOVE
88 XI_EYETRACKER XI_CURSORKEYS XI_FOOTMOUSE XI_JOYSTICK
89 These strings may be used in an XInternAtom request to return
91 an atom that can be compared with the type field of the
92 XDeviceInfo structure.
93 The name field contains a pointer to a null-terminated string
95 that serves as identifier of the device. This identifier may be
96 user-configured or automatically assigned by the server.
97 The num_classes field is a number in the range 0-255 that
99 specifies the number of input classes supported by the device
100 for which information is returned by ListInputDevices. Some
101 input classes, such as class Focus and class Proximity do not
102 have any information to be returned by ListInputDevices.
103 All devices provide an AttachClass. This class specifies the
105 master device a given slave device is attached to. For master
106 devices, the class specifies the respective paired master
107 device.
108 The use field specifies how the device is currently being used.
110 If the value is IsXKeyboard, the device is a master keyboard.
111 If the value is IsXPointer, the device is a master pointer. If
112 the value is IsXExtensionPointer, the device is a slave
113 pointer. If the value is IsXExtensionKeyboard, the device is a
114 slave keyboard. If the value is IsXExtensionDevice, the device
115 is available for use as an extension device.
116 The inputclassinfo field contains a pointer to the first
118 input-class specific data. The first two fields are common to
119 all classes.
120 The class field is a number in the range 0-255. It uniquely
122 identifies the class of input for which information is
123 returned. Currently defined classes are KeyClass, ButtonClass,
124 and ValuatorClass.
125 The length field is a number in the range 0- 255. It specifies
127 the number of bytes of data that are contained in this input
128 class. The length includes the class and length fields.
129 The XKeyInfo structure describes the characteristics of the
131 keys on the device. It is defined as follows:
132 typedef struct _XKeyInfo {
134 XID class;
135 int length;
136 unsigned short min_keycode;
137 unsigned short max_keycode;
138 unsigned short num_keys;
139 } XKeyInfo;
140 min_keycode is of type KEYCODE. It specifies the minimum
142 keycode that the device will report. The minimum keycode will
143 not be smaller than 8.
144 max_keycode is of type KEYCODE. It specifies the maximum
146 keycode that the device will report. The maximum keycode will
147 not be larger than 255.
148 num_keys specifies the number of keys that the device has.
150 The XButtonInfo structure defines the characteristics of the
152 buttons on the device. It is defined as follows:
153 typedef struct _XButtonInfo {
155 XID class;
156 int length;
157 short num_buttons;
158 } XButtonInfo;
159 num_buttons specifies the number of buttons that the device
161 has.
162 The XValuatorInfo structure defines the characteristics of the
164 valuators on the device. It is defined as follows:
165 typedef struct _XValuatorInfo {
167 XID class;
168 int length;
169 unsigned char num_axes;
170 unsigned char mode;
171 unsigned long motion_buffer;
172 XAxisInfoPtr axes;
173 } XValuatorInfo;
174 num_axes contains the number of axes the device supports.
176 mode is a constant that has one of the following values:
178 Absolute or Relative. Some devices allow the mode to be changed
179 dynamically via the SetDeviceMode request.
180 motion_buffer_size is a cardinal number that specifies the
182 number of elements that can be contained in the motion history
183 buffer for the device.
184 The axes field contains a pointer to an XAxisInfo structure.
186 The XAxisInfo structure is defined as follows:
188 typedef struct _XAxisInfo {
190 int resolution;
191 int min_value;
192 int max_value;
193 } XAxisInfo;
194 The resolution contains a number in counts/meter.
196 The min_val field contains a number that specifies the minimum
198 value the device reports for this axis. For devices whose mode
199 is Relative, the min_val field will contain 0.
200 The max_val field contains a number that specifies the maximum
202 value the device reports for this axis. For devices whose mode
203 is Relative, the max_val field will contain 0.
204 The XAttachInfo structure is defined as follows:
206 typedef struct _XAttachInfo {
207 int attached;
208 } XAttachInfo;
209 If the device is a slave device, attached specifies the device
211 ID of the master device this device is attached to. If the
212 device is not attached to a master device, attached is
213 Floating. If the device is a master device, attached specifies
214 the device ID of the master device this device is paired with.
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217 XListInputDevices returns a pointer to an array of XDeviceInfo
218 structs and sets ndevices_return to the number of elements in
219 that array. To free the XDeviceInfo array created by
220 XListInputDevices, use XFreeDeviceList.
221 On error, XListInputDevices returns NULL and ndevices_return is
223 left unmodified.
224 09/15/2021 XLISTINPUTDEVICES(3)