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.\" Copyright (c) 1999, Oracle and/or its affiliates.
.\"
.\" Permission is hereby granted, free of charge, to any person obtaining a
.\" copy of this software and associated documentation files (the "Software"),
.\" to deal in the Software without restriction, including without limitation
.\" the rights to use, copy, modify, merge, publish, distribute, sublicense,
.\" and/or sell copies of the Software, and to permit persons to whom the
.\" Software is furnished to do so, subject to the following conditions:
.\"
.\" The above copyright notice and this permission notice (including the next
.\" paragraph) shall be included in all copies or substantial portions of the
.\" Software.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
.\" IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
.\" FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
.\" THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
.\" LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
.\" FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
.\" DEALINGS IN THE SOFTWARE.
.\"
.TH XkbKeyActionEntry __libmansuffix__ __xorgversion__ "XKB FUNCTIONS"
.SH NAME
XkbKeyActionEntry \- Returns a pointer to the key action corresponding to
group grp and shift level lvl from the two-dimensional table of key actions
associated with the key corresponding to
keycode
.SH SYNOPSIS
.HP
.B XkbAction * XkbKeyActionEntry
.BI "(\^XkbDescPtr " "xkb" "\^,"
.BI "KeyCode " "keycode" "\^,"
.BI "int " "shift" "\^,"
.BI "int " "grp" "\^);"
.if n .ti +5n
.if t .ti +.5i
.SH ARGUMENTS
.TP
.I xkb
Xkb description of interest
.TP
.I keycode
keycode of interest
.TP
.I shift
shift level within group
.TP
.I grp
group index for group of interest
.SH DESCRIPTION
.LP
A key action defines the effect key presses and releases have on the internal
state of the server. For example,
the expected key action associated with pressing the Shift key is to set the
Shift modifier. There is zero or one
key action associated with each keysym bound to each key.
Just as the entire list of key symbols for the keyboard mapping is held in the
.I syms
field of the client map, the entire list of key actions for the keyboard mapping
is held in the
.I acts
array of the server map. The total size of
.I acts
is specified by
.I size_acts,
and the number of entries is specified by
.I num_acts.
The
.I key_acts
array, indexed by keycode, describes the actions associated with a key. The
.I key_acts
array has
.I min_key_code
unused entries at the start to allow direct indexing using a keycode. If a
.I key_acts
entry is zero, it means the key does not have any actions associated with it. If
an entry is not zero, the entry
represents an index into the
.I acts
field of the server map, much as the
.I offset
field of a KeySymMapRec structure is an index into the
.I syms
field of the client map.
The reason the
.I acts
field is a linear list of XkbActions is to reduce the memory consumption
associated with a keymap. Because Xkb
allows individual keys to have multiple shift levels and a different number of
groups per key, a single
two-dimensional array of KeySyms would potentially be very large and sparse.
Instead, Xkb provides a small
two-dimensional array of XkbActions for each key. To store all of these
individual arrays, Xkb concatenates each
array together in the
.I acts
field of the server map.
The key action structures consist only of fields of type char or unsigned char.
This is done to optimize data
transfer when the server sends bytes over the wire. If the fields are anything
but bytes, the server has to sift
through all of the actions and swap any nonbyte fields. Because they consist of
nothing but bytes, it can just
copy them out.
.I XkbKeyActionEntry
returns the key action corresponding to group
.I grp
and shift level
.I lvl
from the two-dimensional table of key actions associated with the key
corresponding to
.I keycode.
.SH STRUCTURES
.LP
The KeySymMapRec structure is defined as follows:
.nf
#define XkbNumKbdGroups 4
#define XkbMaxKbdGroup (XkbNumKbdGroups-1)
typedef struct { /\&* map to keysyms for a single keycode */
unsigned char kt_index[XkbNumKbdGroups]; /\&* key type index for each group */
unsigned char group_info; /\&* # of groups and out of range group handling */
unsigned char width; /\&* max # of shift levels for key */
unsigned short offset; /\&* index to keysym table in syms array */
} XkbSymMapRec, *XkbSymMapPtr;
.fi
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