Ubuntu Manpage: slk_init, slk_set, slk_wset, slk_refresh, slk_noutrefresh, slk_label, slk

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 labels, 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
implementation 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 labnum, 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 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 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 integer 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 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.

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 likely to follow soon.

PORTABILITY

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

       •   It   added  functions  like  the  SVr4  attribute-manipulation  functions  slk_attron,
           slk_attroff, 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.