Provided by: ncurses-doc_6.4+20230625-2_all bug

NAME

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

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

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(3X).

   clearok
       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.

   idlok
       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.

   idcok
       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.

   immedok
       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.

   leaveok
       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.

   scrollok
       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).

   setscrreg/wsetscrreg
       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.)

RETURN VALUE

       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

       •   wsetscrreg 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.

PORTABILITY

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

       From the outset, ncurses used nl/nonl to control the conversion of  newlines  to  carriage
       return/line-feed  on  output as well as input.  XSI Curses documents only the use of these
       functions for input.  This difference 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.   Because  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 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.

NOTES

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

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

SEE ALSO

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