curs_outopts 3x
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 com-
pletely 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 edi-
tor. It is disabled by default because insert/delete line
tends to be visually annoying when used in applications
where it isn't really needed. If insert/delete line can-
not 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 char-
acter 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 inser-
tion 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 wre-
fresh. 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 cur-
sor is not used, since it reduces the need for cursor
motions.
The setscrreg and wsetscrreg routines allow the applica-
tion programmer to set a software scrolling region in a
window. top and bot 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 bet-
ter 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 suc-
cess and ERR upon failure. All other routines that return
an integer always return OK.
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 con-
trolled 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 does not mess with.
Some historic curses implementations had, as an undocu-
mented feature, the ability to do the equivalent of
clearok(..., 1) by saying touchwin(stdscr) or clear(std-
scr). 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, nl, nonl and
setscrreg may be macros.
The immedok routine is useful for windows that are used as
terminal emulators.
SEE ALSO
curses(3x), curs_addch(3x), curs_clear(3x),
curs_initscr(3x), curs_scroll(3x), curs_refresh(3x)
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