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.\"     Title: xopendevice
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.77.1 <http://docbook.sf.net/>
.\"      Date: 03/09/2013
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "XOPENDEVICE" "3" "03/09/2013" "\ \&" "\ \&"
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.SH "NAME"
XOpenDevice, XCloseDevice \- open or close an extension input device
.SH "SYNOPSIS"
.sp
.nf
#include <X11/extensions/XInput\&.h>
.fi
.sp
.nf
XDevice *XOpenDevice( Display *display,
                      XID device_id);
.fi
.sp
.nf
XCloseDevice( Display *display,
              XDevice *device);
.fi
.sp
.nf
display
       Specifies the connection to the X server\&.
.fi
.sp
.nf
device_id
       Specifies the id of the device to be opened
.fi
.sp
.nf
device
       Specifies the device to be closed
.fi
.SH "DESCRIPTION"
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.nf
The XOpenDevice request makes an input device accessible to a
client through input extension protocol requests\&. If
successful, it returns a pointer to an XDevice structure\&.
.fi
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.RE
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.sp
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.nf
The XCloseDevice request makes an input device inaccessible to
a client through input extension protocol requests\&. Before
terminating, and client that has opened input devices through
the input extension should close them via CloseDevice\&.
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.RE
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.nf
When a client makes an XCloseDevice request, any active grabs
that the client has on the device are released\&. Any event
selections that the client has are deleted, as well as any
passive grabs\&. If the requesting client is the last client
accessing the device, the server may disable all access by X to
the device\&.
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.nf
XOpenDevice and XCloseDevice can generate a BadDevice error\&.
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Structures
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The XDevice structure returned by XOpenDevice contains:
             typedef struct {
             XID device_id;
             int num_classes;
             XInputClassInfo *classes;
             } XDevice;
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The classes field is a pointer to an array of XInputClassInfo
structures\&. Each element of this array contains an event type
base for a class of input supported by the specified device\&.
The num_classes field indicates the number of elements in the
classes array\&.
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The XInputClassInfo structure contains:
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typedef struct {
    unsigned char input_class;
    unsigned char event_type_base;
} XInputClassInfo;
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The input_class field identifies one class of input supported
by the device\&. Defined types include KeyClass, ButtonClass,
ValuatorClass, ProximityClass, FeedbackClass, FocusClass, and
OtherClass\&. The event_type_base identifies the event type of
the first event in that class\&.
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The information contained in the XInputClassInfo structure is
used by macros to obtain the event classes that clients use in
making XSelectExtensionEvent requests\&. Currently defined macros
include DeviceKeyPress, DeviceKeyRelease, DeviceButtonPress,
DeviceButtonRelese, DeviceMotionNotify, DeviceFocusIn,
DeviceFocusOut, ProximityIn, ProximityOut, DeviceStateNotify,
DeviceMappingNotify, ChangeDeviceNotify,
DevicePointerMotionHint, DeviceButton1Motion,
DeviceButton2Motion, DeviceButton3Motion, DeviceButton4Motion,
DeviceButton5Motion, DeviceButtonMotion, DeviceOwnerGrabButton,
DeviceButtonPressGrab, and NoExtensionEvent\&.
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To obtain the proper event class for a particular device, one
of the above macros is invoked using the XDevice structure for
that device\&. For example,
             DeviceKeyPress (*device, type, eventclass);
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returns the DeviceKeyPress event type and the eventclass for
DeviceKeyPress events from the specified device\&.
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This eventclass can then be used in an XSelectExtensionEvent
request to ask the server to send DeviceKeyPress events from
this device\&. When a selected event is received via XNextEvent,
the type can be used for comparison with the type in the event\&.
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.SH "DIAGNOSTICS"
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BadDevice
       An invalid device was specified\&. The specified device
       does not exist, or is the X keyboard or X pointer\&. This
       error may also occur if some other client has caused the
       specified device to become the X keyboard or X pointer
       device via the XChangeKeyboardDevice or
       XChangePointerDevice requests\&.
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