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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 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.

       XkbKeyActionsPtr returns a pointer to the two-dimensional array of key
       actions associated with the key corresponding to keycode.  Use
       XkbKeyActionsPtr 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 1.8.2               XkbKeyActionsPtr(3)

xorg-libX11 1.8.2 - Generated Fri Nov 18 05:39:14 CST 2022
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