curs_kernel 3x 2024-06-22 ncurses 6.5 Library calls

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


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


       #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 curs_set(int visibility);
       int mvcur(int oldrow, int oldcol, int newrow, int newcol);
       int napms(int ms);
       int ripoffline(int line, int (*init)(WINDOW *, int));


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

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 stores the coordinates of virtual screen (newscr)  cursor  in  y
       and x.  If newscr's leaveok(3x) output option is TRUE, getsyx stores -1
       in both y and x.  If lines have been removed from the top of the screen
       using  ripoffline, y includes these lines; therefore, y and x populated
       by getsyx should be used only as arguments for setsyx.

       Few applications use this feature; most call getyx(3x) instead.


       setsyx sets the virtual screen (newscr)  cursor  location  to  (y,  x).
       setsyx(-1, -1) is equivalent to leaveok(newscr, TRUE).

       getsyx  and  setsyx  are  designed  to  be  used  by  a  function  that
       manipulates curses windows but  seeks  to  avoid  changing  the  cursor
       position.  Such a function would first call getsyx, modify its windows'
       content,  call  wnoutrefresh(3x)  on  them,  call  setsyx,  then   call

       Few applications use this feature; most call wmove(3x) instead.


       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.


       mvcur provides low-level cursor motion.  It takes  effect  immediately,
       rather  than  at  the  next refresh.  Unlike the other low-level output
       functions, which either write to the  standard  output  stream  or  are
       passed  a  function  pointer  to  perform  output,  mvcur  uses  a file
       descriptor derived from the output stream parameter of newterm(3x).

       One application of mvcur  accompanies  the  temporary  use  of  another
       program  to  write  to  the  terminal  screen.  For example, first call
       refresh(3x) to ensure that the screen and the library's model of it  is
       up  to  date;  then call reset_shell_mode; write to the screen with the
       external application; call reset_prog_mode; and finally call mvcur(...,
       ...,  -1, -1) to move the terminal cursor to where curses thinks it is,
       since the library has no knowledge  of  how  the  external  application
       moved it.


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


       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


       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 ERR if the terminal was not initialized, or if the I/O call
            to obtain the terminal settings fails.

            returns  ERR if the maximum number of ripped-off lines exceeds the
            maximum (5).


       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.


       In ncurses, mvcur accepts -1 for either or both old coordinates.   This
       value  tells ncurses that the old location is unknown, and that it must
       use only absolute motion, as with the cursor_address (cup)  capability,
       rather  than  the  least  costly  combination  of absolute and relative


       Applications employing ncurses extensions should condition their use on
       the visibility of the NCURSES_VERSION preprocessor macro.

       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

       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.

       X/Open Curses notes:

              "After  use  of mvcur(), the model Curses maintains of the state
              of the  terminal  might  not  match  the  actual  state  of  the
              terminal.   An  application  should touch and refresh the window
              before resuming conventional use of Curses."

       Both ncurses and SVr4 curses implement  mvcur  using  the  SCREEN  data
       allocated  in  either initscr(3x) or newterm(3x).  X/Open Curses states
       that the old location must be given for mvcur to accommodate  terminals
       that lack absolute cursor positioning.

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


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

ncurses 6.5                       2024-06-22                   curs_kernel(3x)