curs_slk(3x) — Linux manual page


curs_slk(3X)                                                curs_slk(3X)

NAME         top

       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         top

       #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         top

       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.

       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.

       The slk_set routine (and the slk_wset routine for the wide-
       character library) has three parameters:

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

               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).

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

       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         top

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

       X/Open defines no error conditions.  In this implementation

               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

               returns an error if the terminal or the softkeys were not

               returns an error if the terminal or the softkeys were not
               initialized, or the color pair is outside the range

               returns an error if the terminal or the softkeys were not
               initialized, or the color pair is outside the range

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

               returns NULL on error.

               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

HISTORY         top

       SVr3 introduced these functions:

       SVr4 added these functions:

       X/Open Curses added these:

EXTENSIONS         top

       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         top

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

PORTABILITY         top

       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 symbols.  Reading the source code (i.e.,

       •   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

           Finally, if there is no fln capability, slk_start returns

       •   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

       •   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         top

       curses(3X), curs_attr(3X), curs_initscr(3X), curs_refresh(3X),

COLOPHON         top

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