XkbKeyAction(3) 						   XKB FUNCTIONS						   XkbKeyAction(3)

NAME

       XkbKeyAction -  Returns the key action

SYNOPSIS

       XkbAction XkbKeyAction (XkbDescPtr xkb, KeyCode keycode, int idx);

ARGUMENTS

       - xkb  Xkb description of interest

       - keycode
	      keycode of interest

       - idx  index for group and shift level

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 associated 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 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 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.

       XkbKeyAction  returns  the  key	action indexed by idx in the two-dimensional array of key actions associated with the key corresponding to
       keycode.idx may be computed from the group and shift level of interest as follows:

	   idx = group_index * key_width + shift_level

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 1.6.0 						   XkbKeyAction(3)