curs_outopts(3) UNIX Programmer's Manual curs_outopts(3)
clearok, idlok, idcok, immedok, leaveok, setscrreg,
wsetscrreg, scrollok, nl, nonl - 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 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);
These routines set options that change the style of output
within curses. All options are initially FALSE, unless oth-
erwise 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 con-
siders using the hardware insert/delete line feature of ter-
minals so equipped. Calling idlok with FALSE as second argu-
ment disables use of line insertion and deletion. This op-
tion 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 isn't
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.
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curs_outopts(3) UNIX Programmer's Manual curs_outopts(3)
If immedok is called with TRUE as argument, any change in
the window image, such as the ones caused by waddch, wclrto-
bot, wscrl, etc., automatically cause a call to wrefresh.
However, it may degrade performance considerably, due to re-
peated 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.
top and bot are the line numbers of the top and bottom mar-
gin of the scrolling region. (Line 0 is the top line of the
window.) If this option and scrollok are enabled, an at-
tempt 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 dis-
abled, (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 nl and nonl routines control whether the underlying
display device translates the return key into newline on in-
put, 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 dis-
able them using nonl, curses will be able to make better use
of the line-feed capability, resulting in faster cursor mo-
tion. Also, curses will then be able to detect the return
key.
The functions setscrreg and wsetscrreg return OK upon suc-
cess and ERR upon failure. All other routines that return an
integer always return OK.
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curs_outopts(3) UNIX Programmer's Manual curs_outopts(3)
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 implemen-
tation returns an error if the window pointer is null.
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 re-
questing raw input wants a clean (ideally 8-bit clean) con-
nection 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.
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.
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curs_outopts(3) UNIX Programmer's Manual curs_outopts(3)
curses(3), curs_addch(3), curs_clear(3), curs_initscr(3),
curs_scroll(3), curs_refresh(3)
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