https://invisible-island.net/ncurses/man/
curs_outopts(3x) Library calls curs_outopts(3x)
clearok, idcok, idlok, immedok, leaveok, scrollok, setscrreg,
wsetscrreg - set curses output options
#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);
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.
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.
(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.
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.
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. However, doing so may degrade
performance considerably when many such calls occur. 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.
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 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 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 functions setscrreg and wsetscrreg return OK upon success and ERR
upon failure. All other routines that return an integer always return
OK.
In this implementation,
o those functions that have a window pointer will return ERR if the
window pointer is null
o wsetscrreg returns ERR if the scrolling region limits extend
outside the window boundaries.
clearok, leaveok, scrollok, idcok, and setscrreg may be implemented as
macros.
The immedok routine is useful for windows that are used as terminal
emulators.
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, but
the code neglects it. Use curs_set(3x) to make the cursor invisible.
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).
curses(3x), curs_addch(3x), curs_clear(3x), curs_initscr(3x),
curs_refresh(3x), curs_scroll(3x), curs_variables(3x)
ncurses 6.5 2025-03-08 curs_outopts(3x)