nonl(3x) — Linux manual page


curs_outopts(3X)                                            curs_outopts(3X)

NAME         top

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

SYNOPSIS         top

       #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         top

       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

       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 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 key.

RETURN VALUE         top

       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.

PORTABILITY         top

       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.

NOTES         top

       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

SEE ALSO         top

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

COLOPHON         top

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