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XkbKeyNumActions(3)              XKB FUNCTIONS             XkbKeyNumActions(3)

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

       int XkbKeyNumActions macro ( xkb, keycode )
             XkbDescPtr xkb;
             KeyCode keycode;

       - xkb  Xkb description of interest

       - keycode
              keycode of interest

       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  associ-
       ated  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 poten-
       tially 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.

       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 1.1.5              XkbKeyNumActions(3)