'\" t
.\"     Title: xiselectevents
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: 09/15/2021
.\"    Manual: \ \&
.\"    Source: \ \&
.\"  Language: English
.\"
.TH "XISELECTEVENTS" "libmansuffix" "09/15/2021" "\ \&" "\ \&"
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.SH "NAME"
XISelectEvents, XIGetSelectedEvents \- select for or get selected XI2 events on the window\&.
.SH "SYNOPSIS"
.sp
.nf
#include <X11/extensions/XInput2\&.h>
.fi
.sp
.nf
Status XISelectEvents( Display *display,
                       Window win,
                       XIEventMask *masks,
                       int num_masks);
.fi
.sp
.nf
display
       Specifies the connection to the X server\&.
.fi
.sp
.nf
masks
       Device event mask\&.
.fi
.sp
.nf
num_masks
       Number of masks in masks\&.
.fi
.sp
.nf
win
       Specifies the window\&.
.fi
.sp
.nf
XIEventMask *XIGetSelectedEvents( Display *display,
                                  Window win,
                                  int *num_masks_return);
.fi
.sp
.nf
display
       Specifies the connection to the X server\&.
.fi
.sp
.nf
num_masks_return
       Number of masks in the return value\&.
.fi
.sp
.nf
win
       Specifies the window\&.
.fi
.SH "DESCRIPTION"
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.if n \{\
.RS 4
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.nf
XI2 events must be selected using XISelectEvents\&.
.fi
.if n \{\
.RE
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.RS 4
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.nf
XISelectEvents sets the event mask for this client on win\&.
Further events are only reported to this client if the event
type matches the selected event mask\&. The masks overrides the
previously selected event mask for the given device\&.
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.RE
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.RS 4
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.nf
If deviceid is a valid device, the event mask is selected only
for this device\&. If deviceid is XIAllDevices or
XIAllMasterDevices, the event mask is selected for all devices
or all master devices, respectively\&. The effective event mask
is the bit\-wise OR of the XIAllDevices, XIAllMasterDevices and
the respective device\*(Aqs event mask\&.
.fi
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.RE
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.nf
typedef struct {
    int deviceid;
    int mask_len;
    unsigned char* mask;
} XIEventMask;
.fi
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.RE
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.nf
The mask_len specifies the length of mask in bytes\&. mask is a
binary mask in the form of (1 << event type)\&. deviceid must be
either a device or XIAllDevices or XIAllMasterDevices\&. A client
may submit several masks with the same deviceid in one request
but only the last mask will be effective\&.
.fi
.if n \{\
.RE
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.RS 4
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.nf
XISelectEvents can generate a BadValue, a BadDevice, and a
BadWindow error\&.
.fi
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.RE
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.RS 4
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.nf
XIGetSelectedEvents returns the events selected by this client on the given
window\&. If no events were selected on this window, XIGetSelectedEvents
returns NULL and num_masks_return is set to 0\&. If an internal error occurs,
XIGetSelectedEvents returns NULL and num_masks_return is set to \-1\&.
Otherwise, XIGetSelectedEvent returns the selected event masks for all
devices including the masks for XIAllDevices and XIAllMasterDevices
.fi
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.RE
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The caller must free the returned data using XFree()\&.
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.SH "DIAGNOSTICS"
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BadValue
       A value is outside of the permitted range\&.
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.RE
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.RS 4
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.nf
BadWindow
       A value for a Window argument does not name a defined
       window\&.
.fi
.if n \{\
.RE
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.sp
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.RS 4
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.nf
BadDevice
       An invalid device was specified\&. The device does not
       exist\&.
.fi
.if n \{\
.RE
.\}