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XkbKeyHasActions(3) XKB FUNCTIONS XkbKeyHasActions(3)
NAME
XkbKeyHasActions - Determines if the key corresponding to keycode has any actions associ-
ated with it
SYNOPSIS
int XkbKeyHasActions (XkbDescPtr xkb, KeyCode keycode);
ARGUMENTS
- xkb Xkb description of interest
- keycode
keycode of interest
DESCRIPTION
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 syms field
of the client map, the entire list of key actions for the keyboard mapping is held in the
acts array of the server map. The total size of acts is specified by size_acts, and the
number of entries is specified by num_acts.
The key_acts array, indexed by keycode, describes the actions associated with a key. The
key_acts array has min_key_code unused entries at the start to allow direct indexing using
a keycode. If a key_acts entry is zero, it means the key does not have any actions associ-
ated with it. If an entry is not zero, the entry represents an index into the acts field
of the server map, much as the offset field of a KeySymMapRec structure is an index into
the syms field of the client map.
The reason the acts field is a linear list of XkbActions is to reduce the memory consump-
tion 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 concate-
nates each array together in the 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.
XkbKeyHasActions returns True if the key corresponding to keycode has any actions associ-
ated with it; otherwise, it returns False.
RETURN VALUES
True The XkbKeyHasActions function will return True if the key corresponding to
keycode has any actions associated with it.
False The XkbKeyHasActions function will return False if the key corresponding to
keycode does not have any actions associated with it.
STRUCTURES
The KeySymMapRec structure is defined as follows:
#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;
X Version 11 libX11 1.6.7 XkbKeyHasActions(3)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
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