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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);

       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  screen,  taking into account what is already
       there to	do optimizations.  The refresh routine is the same, using std-
       scr as the default window.  Unless leaveok has been enabled, the	physi-
       cal 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

       o   a physical screen, describing what is actually on the screen, and

       o   a virtual screen, 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
	   virtual screen, and

       o   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 doup-
       date  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 glob-
       al  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-

       X/Open does not define any error	conditions.  In	this implementation

	       returns	an error if the	window pointer is null,	or if the win-
	       dow is really a pad.

	       returns an error	if the associated call to touchln  returns  an

       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 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-

       curses(3X), curs_outopts(3X) curs_variables(3X).



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