Ubuntu Manpage: clearok, idlok, idcok, immedok, leaveok, setscrreg, wsetscrreg, scrollok, nl, nonl

Provided by: ncurses-doc_5.9+20140118-1ubuntu1_all

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 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).

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

       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 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.

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

              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.

       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