NAME

       XkbKeyNumActions - Computes the number of actions associated with the key corresponding to
       keycode

SYNOPSIS

       int XkbKeyNumActions (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
       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.

       XkbKeyNumActions  computes  the number of actions associated with the key corresponding to
       keycode.  This should be the same value as the result of XkbKeyNumSyms.

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;

SEE ALSO

       XkbKeyNumSyms(3)