- 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-
- tures. 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 ter-
- minal is left at the location of the cursor for that win-
- dow.
-
- 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 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
- will be modified only when it is explicitly changed. (But
- 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()
- 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
- 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 refresh and wrefresh routines (or wnoutrefresh and doupdate) must
+ be called to get actual output to the terminal, as other routines mere-
+ ly manipulate data structures. The routine wrefresh copies the named
+ window to the physical terminal screen, taking into account what is al-
+ ready there to do optimizations. The refresh routine is the same, us-
+ ing 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.
+
+
+
+ The wnoutrefresh and doupdate routines allow multiple updates with more
+ efficiency than wrefresh alone. In addition to all the window struc-
+ tures, 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 pos-
+ sible 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 am-
+ biguous. 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 modi-
+ fied only when it is explicitly changed. (But 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 anything is written over
+ them. It touches the indicated lines (marking them changed). The rou-
+ tine 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 com-
+ pletion.
+
+ X/Open does not define any error conditions. In this implementation
+
+ wnoutrefresh
+ returns an error if the window pointer is null, or if the win-
+ dow 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 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 ex-
- plicit touchwin() before the wnoutrefresh() call to guar-
- antee an entire-contents copy anywhere.
+ 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 any-
+ where.
-