NAME

       doupdate,  redrawwin,  refresh,  wnoutrefresh,  wredrawln,  wrefresh  -  refresh  curses windows or lines
       thereupon

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

   refresh, wrefresh
       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  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(3NCURSES)  has  been
       enabled, the physical cursor of the terminal is left at the location of the cursor for that window.

   wnoutrefresh, doupdate
       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 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 physical screen (i.e., 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 modified only when it is explicitly changed.   (But  see  the  section  on
       PORTABILITY below for a warning about exploiting this behavior.)

   wredrawln, redrawwin
       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

       These  routines  return  the integer ERR upon failure and OK (SVr4 specifies only “an integer value 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  guarantee  an  entire-contents
       copy anywhere.

SEE ALSO

       ncurses(3NCURSES), outopts(3NCURSES) curses_variables(3NCURSES)

ncurses 6.4                                        2024-01-05                                  refresh(3NCURSES)