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curs_refresh(3X)					      curs_refresh(3X)

       refresh,	 wrefresh,  wnoutrefresh,  doupdate,  redrawwin,  wredrawln  -
       refresh curses windows and lines

       #include <ncurses.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 in order 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 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
       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
       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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