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curs_slk 3x 2024-05-25 ncurses 6.5 Library calls

curs_slk(3x)                     Library calls                    curs_slk(3x)




NAME

       slk_init,  slk_set,  slk_wset, slk_refresh, slk_noutrefresh, slk_label,
       slk_clear,    slk_restore,    slk_touch,    slk_attron,    slk_attrset,
       slk_attroff,   slk_attr_on,   slk_attr_set,   slk_attr_off,   slk_attr,
       slk_color, extended_slk_color - curses soft label key routines


SYNOPSIS

       #include <curses.h>

       int slk_init(int fmt);

       int slk_set(int labnum, const char *label, int align);
       int slk_wset(int labnum, const wchar_t *label, int align);

       char *slk_label(int labnum);

       int slk_refresh(void);
       int slk_noutrefresh(void);
       int slk_clear(void);
       int slk_restore(void);
       int slk_touch(void);

       int slk_attron(const chtype attrs);
       int slk_attroff(const chtype attrs);
       int slk_attrset(const chtype attrs);
       int slk_attr_on(attr_t attrs, void *opts);
       int slk_attr_off(const attr_t attrs, void *opts);
       int slk_attr_set(const attr_t attrs, short pair, void*opts);
       /* extension */
       attr_t slk_attr(void);

       int slk_color(short pair);
       /* extension */
       int extended_slk_color(int pair);


DESCRIPTION

       These functions manipulate the  soft  function  key  labels  that  some
       hardware  terminals support.  For those terminals that do not have soft
       labels, curses takes over the  bottom  line  of  stdscr,  reducing  its
       vertical  size  and the value of LINES by one.  By default, curses uses
       eight labels of up to eight characters each.

       ncurses furthermore supports a mode comprising twelve labels of  up  to
       five  characters  each,  following a convention associated with the IBM
       PC/AT keyboard.  ncurses simulates this mode by taking over up  to  two
       lines  at the bottom of the screen; it does not try to use any hardware
       support for this mode.


Initialization

       slk_init  must  be  called  before  initscr  or  newterm.   If  initscr
       eventually uses a line from stdscr to emulate the soft labels, then fmt
       determines how the labels are arranged on the screen.

       0  indicates a 3-2-3 arrangement of the labels.

       1  indicates a 4-4 arrangement

       2  indicates the PC-like 4-4-4 mode.

       3  is again the PC-like 4-4-4 mode, but in addition an  index  line  is
          generated,  helping  the  user  to  associate  each  label  with its
          numbered function key.  LINES and the vertical size  of  stdscr  are
          further reduced.


Labels

       Populate  the  labels  with  normal strings (slk_set) or wide-character
       strings (slk_wset).  Each function takes three parameters.

       labnum  is the label number, from 1 to 8 (12 if fmt in slk_init is 2 or
               3);

       label   is  be the string to put on the label, up to eight (five if fmt
               in slk_init is 2 or 3) characters in length.  A empty string or
               a null pointer sets up a blank label.

       align   is  0,  1,  or 2, aligning label to the left, center, or right,
               respectively, within the 8 (5) character cells housing it.

       slk_label obtains the string assigned to label number labnum, with  any
       leading and trailing blanks stripped.


Screen Updates

       slk_refresh  and  slk_noutrefresh  affect  the  soft key label lines as
       wrefresh and wnoutrefresh do the curses window.

       The slk_clear routine clears the soft labels from the screen.

       The slk_restore routine restores the soft labels to the screen after  a
       slk_clear has been performed.

       The  slk_touch routine forces all the soft labels to be output the next
       time a slk_noutrefresh is performed.


Video Attributes

       The  slk_attron,  slk_attrset,  slk_attroff,  and   slk_attr   routines
       correspond  to  attron,  attrset,  attroff, and attr_get, respectively.
       They have an effect only if soft labels are  simulated  on  the  bottom
       line  of  the  screen.   The  default  highlight for soft key labels is
       A_STANDOUT (as in System V curses, which does not document this fact).


Colors

       The slk_color routine corresponds to color_set.  It has an effect  only
       if soft labels are simulated on the bottom line of the screen.

       Because  slk_color  accepts  only short (signed 16-bit integer) values,
       this implementation provides extended_slk_color, which accepts  an  int
       value of at least 32 bits.


RETURN VALUE

       Routines  that  return  an integer return ERR upon failure and OK (SVr4
       specifies only "an integer  value  other  than  ERR")  upon  successful
       completion.

       X/Open Curses defines no error conditions.

       In this implementation

          slk_attr
               returns the attribute used for the soft keys.

          slk_attroff,  slk_attron,  slk_clear,  slk_noutrefresh, slk_refresh,
          slk_touch
               return  ERR  if  the  terminal  or  the   softkeys   were   not
               initialized.

          slk_attrset
               returns   ERR   if  the  terminal  or  the  softkeys  were  not
               initialized.

          slk_attr_set
               returns  ERR  if  the  terminal  or  the  softkeys   were   not
               initialized,   or   the   color   pair  is  outside  the  range
               0..COLOR_PAIRS-1.

          slk_color
               returns  ERR  if  the  terminal  or  the  softkeys   were   not
               initialized,   or   the   color   pair  is  outside  the  range
               0..COLOR_PAIRS-1.

          slk_init
               returns ERR if the format parameter is outside the range 0..3.

          slk_label
               returns NULL on error.

          slk_set
               returns  ERR  if  the  terminal  or  the  softkeys   were   not
               initialized,  or  the  labnum parameter is outside the range of
               label counts, or if the format parameter is outside  the  range
               0..2, or if memory for the labels cannot be allocated.


NOTES

       Most  applications  would  use  slk_noutrefresh  because  a wrefresh is
       likely to follow soon.


EXTENSIONS

       X/Open Curses documents the opts argument as reserved for  future  use,
       saying  that  it must be null.  This implementation uses that parameter
       in ABI 6 for the functions which have a color pair parameter to support
       extended color pairs.

       For  functions  which  modify the color, e.g., slk_attr_set, if opts is
       set it is treated as a pointer to int, and used to set the  color  pair
       instead of the short pair parameter.


PORTABILITY

       X/Open Curses, Issue 4 describes these functions, with some differences
       from SVr4 curses:

       o   X/Open  added  functions  like  the   SVr4   attribute-manipulation
           functions  slk_attron,  slk_attroff, and slk_attrset, but which use
           attr_t parameters (rather than chtype), along with a reserved  opts
           parameter.

           Two  of  these  new  functions  (unlike the SVr4 functions) have no
           provision for color: slk_attr_on and slk_attr_off.

           The third function (slk_attr_set) has a color pair parameter.

       o   It added const qualifiers to parameters (unnecessarily), and

       o   It added slk_color.

       Although slk_start is declared in the curses header file,  it  was  not
       documented by SVr4 other than its presence in a list of libtermlib.so.1
       symbols.  Reading the source code (i.e., Illumos):

       o   slk_start has two parameters:

           o   ng (number of groups) and

           o   gp (group pointer).

       o   Soft-key groups are an array of ng integers.

       o   In SVr4, slk_init calls slk_start passing a null for gp.  For  this
           case,  slk_start  uses  the  number  of  groups ng (3 for the 3-2-3
           layout, 2 for the 4-4 layout) which slk_init provided.

           If ng is  neither  2  or  3,  slk_start  checks  the  terminfo  fln
           (label_format)  capability,  interpreting that as a comma-separated
           list of numbers, e.g., "3,2,3" for the 3-2-3 layout.

           Finally, if there is no fln capability, slk_start returns ERR.

       o   If slk_start is given a non-null gp, it copies the ng  elements  of
           the group of soft-keys, up to 16.

           If there are more than 16 elements, slk_start returns ERR.

       o   The  format  codes  2  and  3 for slk_init were added by ncurses in
           1996.  PDCurses 2.4 added this feature in 2001.

       The function slk_attr was added by ncurses in 1996.

       X/Open Curses does not specify a limit for the  number  of  colors  and
       color pairs which a terminal can support.  However, in its use of short
       for the parameters, it carries over SVr4's  implementation  detail  for
       the compiled terminfo database, which uses signed 16-bit numbers.  This
       implementation provides extended versions of those functions which  use
       int  parameters,  allowing  applications to use larger color- and pair-
       numbers.


HISTORY

       SVr3 introduced these functions:
         slk_clear
         slk_init
         slk_label
         slk_noutrefresh
         slk_refresh
         slk_restore
         slk_set
         slk_touch

       SVr4 added these functions:
         slk_attroff
         slk_attron
         slk_attrset
         slk_start

       X/Open Curses added these:
         slk_attr_off
         slk_attr_on
         slk_attr_set
         slk_color
         slk_wset


SEE ALSO

       curses(3x),    curs_attr(3x),    curs_initscr(3x),    curs_refresh(3x),
       curs_variables(3x)



ncurses 6.5                       2024-05-25                      curs_slk(3x)