# curs_outopts 3x

## NAME

           clearok,   idlok,   idcok,  immedok,  leaveok,  setscrreg,
           wsetscrreg, scrollok, nl, nonl - curses output options

## SYNOPSIS

           #include <curses.h>

           int clearok(WINDOW *win, bool bf);
           int idlok(WINDOW *win, bool bf);
           void idcok(WINDOW *win, bool bf);
           void immedok(WINDOW *win, bool bf);
           int leaveok(WINDOW *win, bool bf);
           int setscrreg(int top, int bot);
           int wsetscrreg(WINDOW *win, int top, int bot);
           int scrollok(WINDOW *win, bool bf);
           int nl(void);
           int nonl(void);

## DESCRIPTION

           These routines set options that change the style of output
           within  curses.   All  options are initially FALSE, unless
           otherwise stated.  It  is  not  necessary  to  turn  these
           options off before calling endwin.

           If  clearok is called with TRUE as argument, the next call
           to wrefresh with this window will clear  the  screen  com-
           pletely  and  redraw the entire screen from scratch.  This
           is useful when the contents of the screen  are  uncertain,
           or  in  some  cases for a more pleasing visual effect.  If
           the win argument to clearok is the global variable curscr,
           the  next  call  to  wrefresh  with  any window causes the
           screen to be cleared and repainted from scratch.

           If idlok is called with TRUE as  second  argument,  curses
           considers using the hardware insert/delete line feature of
           terminals so equipped.  Calling idlok with FALSE as second
           argument  disables  use  of  line  insertion and deletion.
           This option should be  enabled  only  if  the  application
           needs  insert/delete  line, for example, for a screen edi-
           tor.  It is disabled by default because insert/delete line
           tends  to  be  visually annoying when used in applications
           where it isn't really needed.  If insert/delete line  can-
           not  be  used,  curses redraws the changed portions of all
           lines.

           If idcok is called with FALSE as second  argument,  curses
           no longer considers using the hardware insert/delete char-
           acter feature of terminals so equipped.  Use of  character
           insert/delete  is  enabled by default.  Calling idcok with
           TRUE as second argument re-enables use of character inser-
           tion and deletion.

           If  immedok is called with TRUE as argument, any change in
           the window image, such  as  the  ones  caused  by  waddch,
           wclrtobot, wscrl, etc., automatically cause a call to wre-
           fresh.  However, it may degrade performance  considerably,
           due  to  repeated  calls  to  wrefresh.  It is disabled by
           default.

           Normally, the hardware cursor is left at the  location  of
           the  window  cursor  being  refreshed.  The leaveok option
           allows the cursor to be left wherever the  update  happens
           to leave it.  It is useful for applications where the cur-
           sor is not used, since it  reduces  the  need  for  cursor
           motions.

           The  setscrreg  and wsetscrreg routines allow the applica-
           tion programmer to set a software scrolling  region  in  a
           window.   top  and bot are the line numbers of the top and
           bottom margin of the scrolling region.  (Line 0 is the top
           line  of  the  window.)   If  this option and scrollok are
           enabled, an attempt to move off  the  bottom  margin  line
           causes  all  lines  in  the scrolling region to scroll one
           line in the direction of the first line.  Only the text of
           the window is scrolled.  (Note that this has nothing to do
           with the use of a physical scrolling region capability  in
           the terminal, like that in the VT100.  If idlok is enabled
           and  the  terminal  has  either  a  scrolling  region   or
           insert/delete  line capability, they will probably be used
           by the output routines.)

           The scrollok option controls what happens when the  cursor
           of  a  window  is  moved  off  the  edge  of the window or
           scrolling region, either as a result of a  newline  action
           on  the  bottom  line, or typing the last character of the
           last line.  If disabled, (bf is FALSE), the cursor is left
           on  the bottom line.  If enabled, (bf is TRUE), the window
           is scrolled up one line (Note that  to  get  the  physical
           scrolling  effect on the terminal, it is also necessary to
           call idlok).

           The nl and nonl routines control  whether  the  underlying
           display  device  translates the return key into newline on
           input, and whether it translates newline into  return  and
           line-feed  on output (in either case, the call addch('\n')
           does the equivalent of return and line feed on the virtual
           screen).   Initially, these translations do occur.  If you
           disable them using nonl, curses will be able to make  bet-
           ter  use  of the line-feed capability, resulting in faster
           cursor motion.  Also, curses will then be able  to  detect
           the return key.

## RETURN VALUE

           The functions setscrreg and wsetscrreg return OK upon suc-
           cess and ERR upon failure.  All other routines that return
           an integer always return OK.

## PORTABILITY

           These  functions are described in the XSI Curses standard,
           Issue 4.

           The XSI Curses standard is ambiguous on  the  question  of
           whether  raw()  should  disable the CRLF translations con-
           trolled by nl() and nonl().  BSD curses did turn off these
           translations;  AT&T  curses (at least as late as SVr1) did
           not.  We choose to do so, on the theory that a  programmer
           requesting  raw  input wants a clean (ideally 8-bit clean)
           connection that the operating system does not mess with.

           Some historic curses implementations had,  as  an  undocu-
           mented  feature,  the  ability  to  do  the  equivalent of
           clearok(..., 1) by saying touchwin(stdscr)  or  clear(std-
           scr).  This will not work under ncurses.

           Earlier  System  V  curses  implementations specified that
           with scrollok enabled, any window modification  triggering
           a  scroll also forced a physical refresh.  XSI Curses does
           not require this, and ncurses avoids doing it  to  perform
           better vertical-motion optimization at wrefresh time.

           The  XSI  Curses standard does not mention that the cursor
           should be made invisible  as  a  side-effect  of  leaveok.
           SVr4  curses  documentation  does  this, but the code does
           not.  Use curs_set to make the cursor invisible.

## NOTES

           Note that clearok, leaveok, scrollok, idcok, nl, nonl  and
           setscrreg may be macros.

           The immedok routine is useful for windows that are used as
           terminal emulators.

## SEE ALSO

           curses(3x),        curs_addch(3x),         curs_clear(3x),
           curs_initscr(3x), curs_scroll(3x), curs_refresh(3x)