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curs_refresh(3X)					      curs_refresh(3X)

       doupdate,  redrawwin,  refresh, wnoutrefresh, wredrawln,	wrefresh - re-
       fresh 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
       merely manipulate data structures.  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 terminal is left at the location of the cur-
       sor 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-

       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	touch-
       win() before the	wnoutrefresh() call to	guarantee  an  entire-contents
       copy anywhere.

       curses(3X), curs_outopts(3X)



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