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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON |
curs_refresh(3X) curs_refresh(3X)
doupdate, redrawwin, refresh, wnoutrefresh, wredrawln, wrefresh -
refresh curses windows and lines
#include <curses.h>
int refresh(void);
int wrefresh(WINDOW *win);
int wnoutrefresh(WINDOW *win);
int doupdate(void);
int redrawwin(WINDOW *win);
int wredrawln(WINDOW *win, int beg_line, int num_lines);
refresh/wrefresh
The refresh and wrefresh routines (or wnoutrefresh and doupdate) must
be called to get actual output to the terminal, as other routines
merely manipulate data structures. The routine wrefresh copies the
named window to the physical terminal screen, taking into account
what is already there to do optimizations. The refresh routine is
the same, using stdscr as the default window. Unless leaveok has
been enabled, the physical cursor of the terminal is left at the
location of the cursor for that window.
wnoutrefresh/doupdate
The wnoutrefresh and doupdate routines allow multiple updates with
more efficiency than wrefresh alone. In addition to all the window
structures, curses keeps two data structures representing the
terminal screen: a physical screen, describing what is actually on
the screen, and a virtual screen, describing what the programmer
wants to have on the screen.
The routine wrefresh works by first calling wnoutrefresh, which
copies the named window to the virtual screen, and then calling
doupdate, which compares the virtual screen to the physical screen
and does the actual update. If the programmer wishes to output
several windows at once, a series of calls to wrefresh results in
alternating calls to wnoutrefresh and doupdate, causing several
bursts of output to the screen. By first calling wnoutrefresh for
each window, it is then possible to call doupdate once, resulting in
only one burst of output, with fewer total characters transmitted and
less CPU time used. If the win argument to wrefresh is the global
variable curscr, the screen is immediately cleared and repainted from
scratch.
The phrase "copies the named window to the virtual screen" above is
ambiguous. What actually happens is that all touched (changed) lines
in the window are copied to the virtual screen. This affects
programs that use overlapping windows; it means that if two windows
overlap, you can refresh them in either order and the overlap region
will be modified only when it is explicitly changed. (But see the
section on PORTABILITY below for a warning about exploiting this
behavior.)
wredrawln/redrawwin
The wredrawln routine indicates to curses that some screen lines are
corrupted and should be thrown away before anything is written over
them. It touches the indicated lines (marking them changed). The
routine redrawwin touches the entire window.
Routines that return an integer return ERR upon failure, and OK (SVr4
only specifies "an integer value other than ERR") upon successful
completion.
X/Open does not define any error conditions. In this implementation
wnoutrefresh
returns an error if the window pointer is null, or if the
window is really a pad.
wredrawln
returns an error if the associated call to touchln returns an
error.
Note that refresh and redrawwin may be macros.
The XSI Curses standard, Issue 4 describes these functions.
Whether wnoutrefresh copies to the virtual screen the entire contents
of a window or just its changed portions has never been well-
documented in historic curses versions (including SVr4). It might be
unwise to rely on either behavior in programs that might have to be
linked with other curses implementations. Instead, you can do an
explicit touchwin before the wnoutrefresh call to guarantee an
entire-contents copy anywhere.
curses(3X), curs_outopts(3X) curs_variables(3X).
This page is part of the ncurses (new curses) project. Information
about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2017-07-05. If you
discover any rendering problems in this HTML version of the page, or
you believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
curs_refresh(3X)