# 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 ter-
           minal, as other routines  merely  manipulate  data  struc-
           tures.   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 ter-
           minal is left at the location of the cursor for that  win-
           dow.

           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 physi-
           cal 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 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 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 overlap-
           ping 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 any-
           thing 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 value other than
           ERR") upon successful completion.

## NOTES

           Note that refresh and redrawwin may be macros.

## PORTABILITY

           The XSI Curses standard, Issue  4  describes  these  func-
           tions.

           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 anywhere.

## SEE ALSO

           curses(3x), curs_outopts(3x)