Provided by: ncurses-doc_6.4+20240113-1ubuntu2_all bug

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 an error if the terminal or the softkeys were not initialized.

          slk_attrset
               returns an error if the terminal or the softkeys were not initialized.

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

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

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

          slk_label
               returns NULL on error.

          slk_set
               returns an error 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:

       •   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.

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

       •   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):

       •   slk_start has two parameters:

           •   ng (number of groups) and

           •   gp (group pointer).

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

       •   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.

       •   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 an error.

       •   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

       ncurses(3NCURSES),       attr(3NCURSES),       initscr(3NCURSES),       refresh(3NCURSES),
       curses_variables(3NCURSES)