curs_refresh 3x 2023-10-07 ncurses 6.4 Library calls

curs_refresh(3x)                 Library calls                curs_refresh(3x)


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


       #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);



       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(3x) 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

       o   a physical screen, describing what is actually on the screen, and

       o   a virtual screen, describing what the programmer wants to  have  on
           the screen.

       The routine wrefresh works by

       o   first  calling  wnoutrefresh,  which copies the named window to the
           virtual screen, and

       o   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.)


       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.


       Routines  that  return an integer return ERR upon failure, and OK (SVr4
       only specifies "an integer  value  other  than  ERR")  upon  successful

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

               returns  an  error  if  the  window  pointer is null, or if the
               window is really a pad.

               returns an error if the associated call to touchln  returns  an


       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 touchwin
       before the wnoutrefresh  call  to  guarantee  an  entire-contents  copy


       curses(3x), curs_outopts(3x) curs_variables(3x)

ncurses 6.4                       2023-10-07                  curs_refresh(3x)