Provided by: ncurses-doc_6.1-1ubuntu1_all bug


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


       #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);


       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(3X).

       If clearok is called with TRUE as argument, the next call to  wrefresh  with  this  window
       will  clear  the  screen  completely  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

       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  editor.   It  is
       disabled  by default because insert/delete line tends to be visually annoying when used in
       applications where it is not really needed.  If insert/delete line cannot 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 character 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 insertion 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 wrefresh.
       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 cursor is not used, since it reduces
       the need for cursor motions.

       The setscrreg and wsetscrreg routines allow the application programmer to set  a  software
       scrolling  region in a window.  The top and bot parameters 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).

   nl, nonl
       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 better use of the line-feed capability,
       resulting in faster cursor motion.  Also, curses will then be able to  detect  the  return


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

       X/Open Curses does not define any error conditions.

       In this implementation, those functions that have a window pointer will return an error if
       the window pointer is null.

                   returns an error if the cursor position is about to wrap.

                   returns an error if the scrolling region limits extend outside the window.

       X/Open  does not define any error conditions.  This implementation returns an error if the
       window pointer is null.


       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 controlled 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 will not alter.

       Some historic curses implementations had, as an undocumented feature, the  ability  to  do
       the  equivalent of clearok(..., 1) by saying touchwin(stdscr) or clear(stdscr).  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.


       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.


       ncurses(3NCURSES), addch(3NCURSES), clear(3NCURSES), initscr(3NCURSES), scroll(3NCURSES),
       refresh(3NCURSES), curses_variables(3NCURSES).