- refresh curses
windows and lines
int wrefresh(WINDOW *win);
int wnoutrefresh(WINDOW *win);
int redrawwin(WINDOW *win);
int wredrawln(WINDOW *win, int beg_line, int num_lines);
routines (or wnoutrefresh
) must be called to get actual output to the terminal, as other
routines merely manipulate data structures. The routine wrefresh
the named window to the physical terminal screen, taking into account what is
already there to do optimizations. The refresh
routine is the same,
as the default window. Unless leaveok
enabled, the physical cursor of the terminal is left at the location of the
cursor for that window.
routines allow multiple updates with
more efficiency than wrefresh
alone. In addition to all the window
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
copies the named window to the virtual screen, and then calling
, 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
, 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
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.)
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
() touches the entire window.
Routines that return an integer return ERR
upon failure, and OK
(SVr4 only specifies "an integer value other than ERR
X/Open does not define any error conditions. In this implementation
- returns an error if the window pointer is null, or if the window is really
- returns an error if the associated call to touchln returns an
Note that refresh
may be macros.
The XSI Curses standard, Issue 4 describes these functions.
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()
call to guarantee an entire-contents copy anywhere.