The refresh and wrefresh routines (or wnoutrefresh and
doupdate) must be called to get actual output to the ter-
minal, as other routines merely manipulate data struc-
@@ -76,59 +77,70 @@
minal is left at the location of the cursor for that win-
dow.
- 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 physi-
- cal screen, describing what is actually on the screen, and
- a virtual screen, describing what the programmer wants to
+ The wnoutrefresh and doupdate routines allow multiple up-
+ dates with more efficiency than wrefresh alone. In addi-
+ tion 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.
+ 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 out-
+ put to the screen. By first calling wnoutrefresh for each
+ window, it is then possible to call doupdate once, result-
+ ing in only one burst of output, with fewer total charac-
+ ters transmitted and less CPU time used. If the win argu-
+ ment 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 overlap-
- ping windows; it means that if two windows overlap, you
- can refresh them in either order and the overlap region
+ 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 overlap-
+ ping 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
+ see the section on PORTABILITY below for a warning about
exploiting this behavior.)
The wredrawln routine indicates to curses that some screen
- lines are corrupted and should be thrown away before any-
- thing is written over them. It touches the indicated
- lines (marking them changed). The routine redrawwin()
+ lines are corrupted and should be thrown away before any-
+ thing is written over them. It touches the indicated
+ lines (marking them changed). The routine redrawwin()
touches the entire window.
-
RETURN VALUE
- Routines that return an integer return ERR upon failure,
- and OK (SVr4 only specifies "an integer value other than
+
+ 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 im-
+ plementation
+
+ 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.
+
The XSI Curses standard, Issue 4 describes these func-
tions.
@@ -137,23 +149,29 @@
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.
+ other curses implementations. Instead, you can do an ex-
+ plicit touchwin() before the wnoutrefresh() call to guar-
+ antee an entire-contents copy anywhere.