.\"	$NetBSD: curses_refresh.3,v 1.13 2017/01/05 09:46:32 wiz Exp $
.\"
.\" Copyright (c) 2002
.\"	Brett Lymn (blymn@NetBSD.org, brett_lymn@yahoo.com.au)
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.Dd January 2, 2017
.Dt CURSES_REFRESH 3
.Os
.Sh NAME
.Nm curses_refresh ,
.Nm refresh ,
.Nm wrefresh ,
.Nm wnoutrefresh ,
.Nm doupdate ,
.Nm immedok ,
.Nm flushok ,
.Nm leaveok ,
.Nm is_leaveok
.Nd curses terminal update routines
.Sh LIBRARY
.Lb libcurses
.Sh SYNOPSIS
.In curses.h
.Ft int
.Fn refresh "void"
.Ft int
.Fn wrefresh "WINDOW *win"
.Ft int
.Fn wnoutrefresh "WINDOW *win"
.Ft int
.Fn doupdate "void"
.Ft int
.Fn immedok "WINDOW *win" "boolf flag"
.Ft int
.Fn flushok "WINDOW *win" "boolf flag"
.Ft int
.Fn leaveok "WINDOW *win" "boolf flag"
.Ft bool
.Fn is_leaveok "const WINDOW *win"
.Sh DESCRIPTION
These functions update the terminal with the contents of
.Dv stdscr
or of the specified window(s).
.Pp
The
.Fn refresh
function causes curses to propagate changes made to
.Dv stdscr
to the terminal display.
Any changes made to subwindows of
.Dv stdscr
are also propagated.
.Pp
The
.Fn wrefresh
function is the same as the
.Fn refresh
function, excepting that changes are propagated to the terminal from the
window specified by
.Fa win .
.Pp
The
.Fn wnoutrefresh
function performs the internal processing required by curses to determine
what changes need to be made to synchronise the internal screen buffer
and the terminal but does not modify the terminal display.
.Pp
The
.Fn doupdate
function updates the terminal display to match the internal curses
representation of the display.
.Pp
The
.Fn wnoutrefresh
and
.Fn doupdate
functions can be used together to speed up terminal redraws by
deferring the actual terminal updates until after a batch of updates
to multiple windows has been done.
.Pp
The
.Fn refresh
function is equivalent to
.Fn wnoutrefresh stdscr
followed by
.Fn doupdate .
.Pp
The
.Fn immedok
function determines whether the screen is refreshed whenever the window is
changed.
The initial state is
.Dv FALSE .
.Pp
The
.Fn flushok
function is used to determine whether or not the screen's output file
descriptor will be flushed on refresh.
Setting
.Fa flag
to
.Dv TRUE
will cause the output to be flushed.
.Pp
The
.Fn leaveok
function determines whether refresh operations may leave the screen cursor
in an arbitrary position on the screen.
Setting
.Fa flag
to
.Dv FALSE
ensures that the screen cursor is positioned at the current cursor
position after a refresh operation has taken place.
The
.Fn is_leaveok
function returns the setting.
.Sh RETURN VALUES
Functions returning pointers will return
.Dv NULL
if an error is detected.
The functions that return an int will return one of the following
values:
.Pp
.Bl -tag -width ERR -compact
.It Er OK
The function completed successfully.
.It Er ERR
An error occurred in the function.
.El
.Sh SEE ALSO
.Xr curses_pad 3 ,
.Xr curses_touch 3 ,
.Xr getch 3
.Sh NOTES
Calling
.Fn wrefresh
on a new, unchanged window has no effect.
.Sh STANDARDS
The
.Nx
Curses library complies with the X/Open Curses specification, part of the
Single Unix Specification.
.Sh HISTORY
The Curses package appeared in
.Bx 4.0 .
The
.Fn is_leaveok
function is a
.Em ncurses
extension to the Curses library and was added in
.Nx 8.0 .