clearok, idlok, idcok, immedok, leaveok,
setscrreg, wsetscrreg, scrollok - curses output
int clearok(WINDOW *win, bool
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 scrollok(WINDOW *win, bool bf);
int setscrreg(int top, int
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 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 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 immedok is called with TRUE as argument, any change in the
window image, such as the ones caused by waddch, wclrtobot, wscrl,
etc., automatically cause a call to wrefresh. However, it may degrade
performance considerably, due to repeated 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 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.
int wsetscrreg(WINDOW *win, int top, int
X/Open Curses 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
- wsetscrreg returns an error if the scrolling region limits extend
outside the window.
X/Open does not define any error conditions. This implementation
returns an error if the window pointer is null.
These functions are described in the XSI Curses standard, Issue 4.
From the outset, ncurses used nl/nonl to control the
conversion of newlines to carriage return/line-feed on output as well as
input. XSI Curses documents only the use of these functions for input. This
difference arose from converting the pcurses source (which used
ioctl calls with the sgttyb structure) to termios (i.e., the
POSIX terminal interface). In the former, both input and output were
controlled via a single option CRMOD, while the latter separates
these features. Because that conversion interferes with output optimization,
nl/nonl were amended after ncurses 6.2 to eliminate their
effect on output.
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
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
Note that clearok, leaveok, scrollok, idcok, and
setscrreg may be macros.
The immedok routine is useful for windows that are used as