NAME¶
clearok,
idlok,
idcok,
immedok,
leaveok,
setscrreg,
wsetscrreg,
scrollok,
nl,
nonl -
curses output options
SYNOPSIS¶
#include <curses.h>
int clearok(WINDOW *win, bool bf);
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 setscrreg(int top, int bot);
int wsetscrreg(WINDOW *win, int top, int bot);
int scrollok(WINDOW *win, bool bf);
int nl(void);
int nonl(void);
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.
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
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
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
nl and
nonl routines control whether the underlying display
device translates the return key into newline on input, and whether it
translates newline into return and line-feed on output (in either case, the
call
addch('\n') does the equivalent of return and line feed on the
virtual screen). Initially, these translations do occur. If you disable them
using
nonl,
curses will be able to make better use of the
line-feed capability, resulting in faster cursor motion. Also,
curses
will then be able to detect the return key.
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.
X/Open 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.
- wclrtoeol
- returns an error if the cursor position is about to wrap.
- 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.
PORTABILITY¶
These functions are described in the XSI Curses standard, Issue 4.
The XSI Curses standard is ambiguous on the question of whether
raw()
should disable the CRLF translations controlled by
nl() and
nonl(). BSD curses did turn off these translations; AT&T curses (at
least as late as SVr1) did not. We choose to do so, on the theory that a
programmer requesting raw input wants a clean (ideally 8-bit clean) connection
that the operating system will not alter.
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 under
ncurses.
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 invisible.
NOTES¶
Note that
clearok,
leaveok,
scrollok,
idcok,
nl,
nonl and
setscrreg may be macros.
The
immedok routine is useful for windows that are used as terminal
emulators.
SEE ALSO¶
ncurses(3NCURSES),
addch(3NCURSES),
clear(3NCURSES),
initscr(3NCURSES),
scroll(3NCURSES),
refresh(3NCURSES),
curses_variables(3NCURSES).