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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON |
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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 screen, taking into ac‐
count what is already there to do optimizations. The refresh
routine is the same, using stdscr as the default window. Unless
leaveok(3X) 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 se‐
ries 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 physical screen (i.e., 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 writ‐
ten 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 suc‐
cessful completion.
X/Open does not define any error conditions. In this implementa‐
tion
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 re‐
turns 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 con‐
tents 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. Informa‐
tion 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
[email protected]. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨https://github.com/mirror/ncurses.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2023-03-12.) 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
[email protected]
curs_refresh(3X)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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