XkbKeyActionsPtr man page on Raspbian

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XkbKeyActionsPtr(3)		 XKB FUNCTIONS		   XkbKeyActionsPtr(3)

NAME
       XkbKeyActionsPtr	 -   Returns a pointer to the two-dimensional array of
       key actions associated with the key corresponding to keycode

SYNOPSIS
       XkbKeyActionPtr XkbKeyActionsPtr (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  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.

       XkbKeyActionsPtr returns a pointer to the two-dimensional array of  key
       actions	associated with the key corresponding to keycode.  Use XkbKey‐
       ActionsPtr only if the key actually has some  actions  associated  with
       it,  that is, XkbKeyNumActions (xkb, keycode) returns something greater
       than zero.

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
       XkbKeyNumActions(3)

X Version 11			 libX11 1.3.3		   XkbKeyActionsPtr(3)
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