# curs_slk 3x

    curs_slk(3x)                                                      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 routines

## SYNOPSIS

           #include <curses.h>

           int slk_init(int fmt);

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

           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

           The slk* functions manipulate the set of soft function-key labels  that
           exist on many terminals.  For those terminals that do not have soft la-
           bels, curses takes over the bottom line of stdscr, reducing the size of
           stdscr  and the variable LINES.  curses standardizes on eight labels of
           up to eight characters each.  In addition to this, the  ncurses  imple-
           mentation  supports  a  mode where it simulates 12 labels of up to five
           characters each.  This is useful for PC-like enduser devices.   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

           The slk_init routine must  be  called  before  initscr  or  newterm  is
           called.   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 identify the key numbers easily.

### Labels

           The slk_set routine (and the slk_wset routine  for  the  wide-character
           library) has 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 null string or
                   a null pointer sets up a blank label.

              fmt  is either 0, 1, or 2, indicating whether the  label  is  to  be
                   left-justified,  centered,  or  right-justified,  respectively,
                   within the label.

           The slk_label routine returns the current label for label  number  lab-
           num, with leading and trailing blanks stripped.

### Screen updates

           The slk_refresh and slk_noutrefresh routines correspond to the wrefresh
           and wnoutrefresh routines.

           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  corre-
           spond  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 keys 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  inte-
           ger value, e.g., 32-bits.

## RETURN VALUE

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

           X/Open 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 ini-
                   tialized.

              slk_attrset
                   returns an error if the terminal or the softkeys were not  ini-
                   tialized.

              slk_attr_set
                   returns  an error if the terminal or the softkeys were not ini-
                   tialized, or the  color  pair  is  outside  the  range  0..COL-
                   OR_PAIRS-1.

              slk_color
                   returns  an error if the terminal or the softkeys were not ini-
                   tialized, or the  color  pair  is  outside  the  range  0..COL-
                   OR_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  ini-
                   tialized, 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.

## 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

## 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.

## NOTES

           Most applications would use slk_noutrefresh because a wrefresh is like-
           ly to follow soon.

## PORTABILITY

           The  XSI  Curses  standard,  Issue 4, described the soft-key functions,
           with some differences from SVr4 curses:

           o   It added functions like the SVr4  attribute-manipulation  functions
               slk_attron,  slk_attroff, slk_attrset, but which use attr_t parame-
               ters (rather than chtype), along with a reserved opts parameter.

               Two of these new functions (unlike the SVr4 functions) have no pro-
               vision 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  lay-
               out, 2 for the 4-4 layout) which slk_init provided.

               If  ng  is  neither  2 or 3, slk_start checks the terminfo fln (la-
               bel_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 an error.

           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.

## SEE ALSO

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

                                                                      curs_slk(3x)