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  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 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,  re‐
       sulting  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  re‐
       painted 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  rou‐
       tine 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.

       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).

                                                                                               refresh(3NCURSES)