unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (Debian-5.0)
Page:
Section:
Apropos / Subsearch:
optional field

XkbKeyAction(3)                  XKB FUNCTIONS                 XkbKeyAction(3)



NAME
       XkbKeyAction -  Returns the key action

SYNOPSIS
       XkbAction XkbKeyAction ( xkb, keycode, idx )
             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 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.

       XkbKeyAction  returns  the  key action indexed by idx in the two-dimen-
       sional 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 1.1.5                  XkbKeyAction(3)