curs_outopts 3x

curs_outopts(3x)                                              curs_outopts(3x)


       clearok, idlok, idcok, immedok, leaveok, setscrreg, wsetscrreg,
       scrollok - 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 scrollok(WINDOW *win, bool bf);

       int setscrreg(int top, int bot);
       int wsetscrreg(WINDOW *win, int top, int bot);


       These routines set options that change the style of output within curs-
       es.   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 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 inser-
       tion  and deletion.  This option should be enabled only if the applica-
       tion needs insert/delete line, for example, for a screen editor.  It is
       disabled by default because insert/delete line tends to be visually an-
       noying when used in applications where it is not really needed.  If in-
       sert/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 con-
       siders  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., auto-
       matically cause a call to wrefresh.  However, it  may  degrade  perfor-
       mance  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  appli-
       cations  where  the  cursor  is not used, since it reduces the need for
       cursor motions.


       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 char-
       acter 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 ter-
       minal, it is also necessary to call idlok).


       The setscrreg and wsetscrreg routines allow the application  programmer
       to set a software scrolling region in a window.  The top and bot param-
       eters 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 op-
       tion 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 functions setscrreg and wsetscrreg return OK upon success  and  ERR
       upon  failure.  All other routines that return an integer always return

       X/Open Curses does not define any error conditions.

       In this implementation,

       o   those functions that have a window pointer will return an error  if
           the window pointer is null

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

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


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

       From the outset, ncurses used nl/nonl to control the conversion of new-
       lines to carriage return/line-feed on output as  well  as  input.   XSI
       Curses  documents only the use of these functions for input.  This dif-
       ference arose from converting the  pcurses  source  (which  used  ioctl
       calls  with  the sgttyb structure) to termios (i.e., the POSIX terminal
       interface).  In the former, both input and output were controlled via a
       single  option  CRMOD,  while the latter separates these features.  Be-
       cause that conversion interferes with output optimization, nl/nonl were
       amended after ncurses 6.2 to eliminate their effect on output.

       Some  historic  curses implementations had, as an undocumented feature,
       the ability to do the equivalent of clearok(..., 1)  by  saying  touch-
       win(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

       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 invisi-


       Note that clearok, leaveok,  scrollok,  idcok,  and  setscrreg  may  be

       The immedok routine is useful for windows that are used as terminal em-


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