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curs_outopts(3X) curs_outopts(3X)
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 use-
ful 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 in-
sert/delete line feature of terminals so equipped. Calling idlok with FALSE as second ar-
gument 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 annoying when used in ap-
plications 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 in-
sert/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 re-
freshed. 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 ca-
pability, 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 bot-
tom 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 nec-
essary to call idlok).
The nl and nonl routines control whether the underlying display device translates the re-
turn 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, re-
sulting 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 transla-
tions; 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 re-
quire 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
curses(3X), curs_addch(3X), curs_clear(3X), curs_initscr(3X), curs_scroll(3X), curs_re-
fresh(3X), curs_variables(3X).
curs_outopts(3X)
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Under GNU General Public License
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