curs_outopts(3X) Library calls curs_outopts(3X)
NAME
clearok, idcok, idlok, immedok, leaveok, scrollok, setscrreg, wsetscrreg
- set curses output options
SYNOPSIS
#include <curses.h>
int clearok(WINDOW * win, bool bf);
void idcok(WINDOW * win, bool bf);
int idlok(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 functions configure properties of curses windows that affect their
manner of output. Boolean-valued properties are initially FALSE except
where noted. endwin(3X) resets any terminal modes corresponding to these
properties; an application need not restore their initial values.
clearok
Setting win's clearok property to TRUE causes the next wrefresh call on
it to clear the terminal screen and redraw it entirely. This property is
useful to restore the contents of the screen (perhaps because another
process has written to the terminal), or in some cases to achieve a more
pleasing visual effect. If win is curscr (see curs_variables(3X)), the
next wrefresh call on any window causes the terminal screen to clear and
redraw as above. wrefresh resets this property to FALSE.
idcok
(This property defaults TRUE.) Setting win's idcok property to FALSE
prevents curses from using the insert/delete character capabilities of
terminal types possessing them according to the terminfo database.
idlok
Setting win's idlok property to TRUE causes curses to consider using the
insert/delete line capabilities of terminal types possessing them
according to the terminfo database. Enable this option if the
application explicitly requires these operations, as a full-screen text
editor might; otherwise the results may be visually annoying to the user.
immedok
If immedok is called with TRUE as second argument, changes to the window
image, such as those caused by waddch, wclrtobot, or wscrl, automatically
cause a call to wrefresh. Setting a window's immedok property may
degrade performance considerably if writes are frequent. Calling immedok
with FALSE as second argument restores the default behavior, deferring
screen updates until a refresh is needed or explicitly directed by the
application.
leaveok
Normally, curses leaves the hardware cursor at the library's cursor
location of the window being refreshed. The leaveok option allows the
cursor to be left wherever the update happens to leave it. It is useful
for applications that do not employ a visible cursor, since it reduces
the need for cursor motions.
scrollok
The scrollok option controls what happens when a window's cursor moves
off the edge of the window or scrolling region, as a result of either (1)
writing a newline anywhere on its bottom line, or (2) writing a character
that advances the cursor to the last position on its bottom line. If
disabled (bf is FALSE), curses leaves the cursor on the bottom line of
the window. If enabled (bf is TRUE), curses scrolls the window up one
line. (To get the physical scrolling effect on the terminal, the
application must also enable idlok).
setscrreg, wsetscrreg
The wsetscrreg and setscrreg functions allow the application to set a
software scrolling region in the specified window or stdscr,
respectively. The top and bot parameters are the line numbers of the top
and bottom margin of the scrolling region. 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. (This process has
nothing to do with the scrolling region capability of the terminal, as
found in the DEC 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.
In ncurses, these functions fail if
o the curses screen has not been initialized,
o (for functions taking a WINDOW pointer argument) win is a null
pointer, or
o (for setscrreg and wsetscrreg) the function is passed arguments
describing a scrolling region with limits that extend outside the
window boundaries.
NOTES
clearok, leaveok, scrollok, idcok, and setscrreg may be implemented as
macros.
Unlike the other functions described by this page, setscrreg does not
accept a pointer-to-WINDOW parameter, but operates on stdscr. Use
wsetscrreg to configure the scrolling region of a selected window.
Historically, applications used idcok(FALSE) to accommodate the "magic
cookie" feature of some terminal types; see subsection "Highlighting,
Underlining, and Visible Bells" of terminfo(5). When updating a line,
the presence of character cells with magic cookies in them made the
curses library's computations of characters to be rewritten inaccurate.
A better solution is to indicate the magic_cookie_glitch (xmc) capability
in the terminal's type description.
immedok is useful for windows that are used as terminal emulators.
PORTABILITY
X/Open Curses Issue 4 describes these functions. It specifies no error
conditions for them.
Some historic curses implementations, as an undocumented feature, did the
equivalent of "clearok(..., 1)" when touchwin(stdstr) or clear(stdstr)
were used. This trick does not work with ncurses.
Early System V curses implementations specified that with scrollok
enabled, any window modification triggering a scroll also forced a
physical refresh. X/Open Curses does not require this, and ncurses
avoids doing so to better optimize vertical motions upon a wrefresh.
X/Open Curses does not mention that the cursor should be made invisible
as a side effect of leaveok. SVr4 curses documentation notes this
behavior, but the code neglects to implement it. Use curs_set(3X) to
make the cursor invisible.
HISTORY
4BSD (1980) introduced clearok, leaveok, and scrollok.
SVr2 (1984) supplied idlok, setscrreg, and wsetscrreg.
SVr3.1 (1987) implemented idcok and immedok.
ncurses formerly treated nl and nonl as both input and output options,
but no longer; see curs_inopts(3X).
SEE ALSO
curses(3X), curs_addch(3X), curs_clear(3X), curs_initscr(3X),
curs_refresh(3X), curs_scroll(3X), curs_variables(3X)
ncurses 6.6 2025-11-11 curs_outopts(3X)