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.
+ 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 physicalscreen, taking into account 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.
-
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
+ efficiency than wrefresh alone. In addition to all the window
+ structures, curses keeps two data structures representing the terminal
+ screen:
+
+ o a physicalscreen, describing what is actually on the screen, and
+
+ o a virtualscreen, describing what the programmer wants to have on
+ the screen.
+
+ The routine wrefresh works by
+
+ o first calling wnoutrefresh, which copies the named window to the
+ virtualscreen, and
+
+ o then calling doupdate, which compares the virtualscreen to the
+ physicalscreen 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 physicalscreen (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 modi-
- fied only when it is explicitly changed. (But see the section on
+ 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 anything is written over
- them. It touches the indicated lines (marking them changed). The rou-
- tine redrawwin touches the entire window.
+ 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 com-
- pletion.
+ These routines return the integer ERR upon failure and OK (SVr4
+ specifies only "an integer value other than ERR") upon successful
+ completion.
- X/Open does not define any error conditions. In this implementation
+ X/Open Curses does not specify 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.
+ returns ERR 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.
+ return ERR if the associated call to touchln returns ERR.
- The XSI Curses standard, Issue 4 describes these functions.
+ X/Open Curses, 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 any-
- where.
+ before the wnoutrefresh call to guarantee an entire-contents copy
+ anywhere.