outopts(3NCURSES) Library calls outopts(3NCURSES)
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 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(3NCURSES).
clearok
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.
idcok
If idcok is called with FALSE as second argument, curses no longer con-
siders 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.
idlok
If idlok is called with TRUE as second argument, curses considers using
the hardware insert/delete line feature of terminals so equipped. Call-
ing 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 dis-
abled by default because insert/delete line tends to be visually annoy-
ing when used in applications where it is not really needed. If in-
sert/delete line cannot be used, curses redraws the changed portions of
all lines.
immedok
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 per-
formance considerably, due to repeated calls to wrefresh. Calling imme-
dok with FALSE as second argument restores the default behavior, i.e.,
deferring screen updates until a refresh is needed.
leaveok
Normally, the hardware cursor is left at the location of the window cur-
sor 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 mo-
tions.
scrollok
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).
setscrreg, wsetscrreg
The setscrreg and wsetscrreg routines allow the application programmer
to set a software scrolling region in a window. The top and bot parame-
ters 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 di-
rection 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.)
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 this implementation,
• those functions that have a window pointer will return ERR if the
window pointer is null
• wsetscrreg returns ERR if the scrolling region limits extend outside
the window boundaries.
NOTES
clearok, leaveok, scrollok, idcok, and setscrreg may be implemented as
macros.
The immedok routine is useful for windows that are used as terminal emu-
lators.
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 en-
abled, any window modification triggering a scroll also forced a physi-
cal 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(3NCURSES) to make the cursor invisi-
ble.
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 inopts(3NCURSES).
SEE ALSO
ncurses(3NCURSES), addch(3NCURSES), clear(3NCURSES), initscr(3NCURSES),
refresh(3NCURSES), scroll(3NCURSES), curses_variables(3NCURSES)
ncurses 6.5 2025-02-01 outopts(3NCURSES)
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