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 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(3x).
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 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 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 immedok is called with TRUE as second argument, any change in the
window image, such as the ones caused by waddch, wclrtobot, wscrl,
etc., automatically causes a call to wrefresh. However, it may degrade
performance considerably, due to repeated calls to wrefresh. Calling
immedok with FALSE as second argument restores the default behavior,
i.e., deferring screen updates until a refresh is needed.
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.
Note that clearok, leaveok, scrollok, idcok, and setscrreg may be
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(3x).
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.
ncurses formerly treated nl(3x) and nonl(3x) 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 2024-09-14 curs_outopts(3x)