curs_slk 3x 2023-11-25 ncurses 6.4 Library calls

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


       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


       #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);


       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

          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

               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 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.


       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

               returns the attribute used for the soft keys.

          slk_attroff,  slk_attron,  slk_clear,  slk_noutrefresh, slk_refresh,
               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

               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 allocated.


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


       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.


       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
           parameters  (rather  than  chtype),  along  with  a  reserved  opts

           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
       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 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-


       SVr3 introduced these functions:

       SVr4 added these functions:

       X/Open curses added these:


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

ncurses 6.4                       2023-11-25                      curs_slk(3x)