# curs_kernel 3x 2024-04-20 ncurses 6.5 Library calls

    curs_kernel(3x)                  Library calls                 curs_kernel(3x)

## NAME

           def_prog_mode,   def_shell_mode,   reset_prog_mode,   reset_shell_mode,
           resetty, savetty, getsyx, setsyx, ripoffline, curs_set,  napms  -  low-
           level curses routines

## SYNOPSIS

           #include <curses.h>

           int def_prog_mode(void);
           int def_shell_mode(void);

           int reset_prog_mode(void);
           int reset_shell_mode(void);

           int resetty(void);
           int savetty(void);

           void getsyx(int y, int x);
           void setsyx(int y, int x);

           int ripoffline(int line, int (*init)(WINDOW *, int));
           int curs_set(int visibility);
           int napms(int ms);

## DESCRIPTION

           The   following  routines  give  low-level  access  to  various  curses
           capabilities.   These  routines  typically  are  used  inside   library
           routines.

### def_prog_mode, def_shell_mode

           The def_prog_mode and def_shell_mode routines save the current terminal
           modes as the "program" (in curses) or "shell" (not in curses) state for
           use by the reset_prog_mode and reset_shell_mode routines.  This is done
           automatically by initscr.  There is one such save area for each  screen
           context allocated by newterm.

### reset_prog_mode, reset_shell_mode

           The  reset_prog_mode and reset_shell_mode routines restore the terminal
           to "program" (in curses) or "shell" (out of curses) state.   These  are
           done  automatically by endwin(3x) and, after an endwin, by doupdate, so
           they normally are not called.

### resetty, savetty

           The resetty and savetty routines save and  restore  the  state  of  the
           terminal  modes.   savetty  saves  the  current  state  in a buffer and
           resetty restores the state to what it was at the last call to savetty.

### getsyx

           The getsyx routine returns  the  current  coordinates  of  the  virtual
           screen  cursor in y and x.  If leaveok is currently TRUE, then -1,-1 is
           returned.  If lines have been removed from the top of the screen, using
           ripoffline,  y  and x include these lines; therefore, y and x should be
           used only as arguments for setsyx.

           Few applications will use this feature, most use getyx instead.

### setsyx

           The setsyx routine sets the virtual screen cursor to y, x.  If y and  x
           are  both  -1, then leaveok is set.  The two routines getsyx and setsyx
           are designed to be used by a library routine, which manipulates  curses
           windows  but  does  not  want  to  change  the  current position of the
           program's cursor.   The  library  routine  would  call  getsyx  at  the
           beginning, do its manipulation of its own windows, do a wnoutrefresh on
           its windows, call setsyx, and then call doupdate.

           Few applications will use this feature, most use wmove instead.

### ripoffline

           ripoffline provides access to the same facility that slk_init(3x)  uses
           to  reduce  the  size  of the screen.  ripoffline must be called before
           initscr or newterm is called, to prepare these initial actions:

           o   If line is positive, a line is removed from the top of stdscr.

           o   if line is negative, a line is removed from the bottom.

           When the resulting initialization is done inside initscr,  the  routine
           init (supplied by the user) is called with two arguments:

           o   a window pointer to the one-line window that has been allocated and

           o   an integer with the number of columns in the window.

           Inside  this  initialization  routine,  the integer variables LINES and
           COLS (defined in <curses.h>) are not  guaranteed  to  be  accurate  and
           wrefresh  or  doupdate  must  not  be  called.  It is allowable to call
           wnoutrefresh during the initialization routine.

           ripoffline can be called up to five times  before  calling  initscr  or
           newterm.

### curs_set

           The  curs_set  routine  sets  the cursor state to invisible, normal, or
           very visible for visibility equal to 0, 1, or 2 respectively.   If  the
           terminal  supports  the visibility requested, the previous cursor state
           is returned; otherwise, ERR is returned.

### napms

           napms sleeps  for  ms  milliseconds.   If  ms  exceeds  30,000  (thirty
           seconds), it is capped at that value.

## RETURN VALUE

           Except for curs_set, these routines always return OK.

           curs_set  returns  the  previous  cursor state, or ERR if the requested
           visibility is not supported.

           X/Open defines no error conditions.  In this implementation

           def_prog_mode, def_shell_mode, reset_prog_mode, reset_shell_mode
                return an error if the terminal was not initialized, or if the I/O
                call to obtain the terminal settings fails.

           ripoffline
                returns an error if the maximum number of ripped-off lines exceeds
                the maximum (5).

## NOTES

           Note that getsyx is a macro, so & is not necessary before the variables
           y and x.

           Older  SVr4  man  pages  warn  that  the  return  value of curs_set "is
           currently incorrect".  This implementation gets it right, but it may be
           unwise to count on the correctness of the return value anywhere else.

           Both ncurses and SVr4 will call curs_set in endwin if curs_set has been
           called to make the cursor other than normal, i.e., either invisible  or
           very  visible.   There  is  no way for ncurses to determine the initial
           cursor state to restore that.

## PORTABILITY

           The virtual screen functions setsyx and getsyx  are  not  described  in
           X/Open Curses, Issue 4.  All other functions are as described in X/Open
           Curses.

           The SVr4 documentation describes setsyx and  getsyx  as  having  return
           type  int.   This  is misleading, as they are macros with no documented
           semantics for the return value.

           If interrupted, ncurses restarts napms.  That, and the limitation to 30
           seconds, are different from other implementations.

## SEE ALSO

           curses(3x),   curs_initscr(3x),   curs_outopts(3x),   curs_refresh(3x),
           curs_scr_dump(3x), curs_slk(3x), curs_variables(3x)

    ncurses 6.5                       2024-04-20                   curs_kernel(3x)