Ubuntu Manpage: clearok, idcok, idlok, immedok, leaveok, scrollok, setscrreg, wsetscrreg

name
synopsis
description
return value
notes
portability
history
see also

Provided by: ncurses-doc_6.5+20250216-1_all

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 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.

idlok
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.

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 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.

leaveok
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.

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 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.)

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 emulators.

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  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.

       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 invisible.

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).