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curs_refresh(3X)                                                                            curs_refresh(3X)



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

SYNOPSIS
       #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);

DESCRIPTION
       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 op-timizations. optimizations.
       timizations.  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 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 virtu-al virtual
       al 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 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 global variable curscr, the screen is im-mediately immediately
       mediately 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 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 routine redrawwin() touches the entire window.

RETURN VALUE
       Routines that return an integer return ERR upon failure, and OK (SVr4 only specifies "an integer val-ue value
       ue other than ERR") upon successful completion.

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

              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.

NOTES
       Note that refresh and redrawwin may be macros.

PORTABILITY
       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  guar-antee guarantee
       antee an entire-contents copy anywhere.

SEE ALSO
       curses(3X), curs_outopts(3X)



                                                                                            curs_refresh(3X)