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curs_refresh 3x 2025-01-18 ncurses 6.5 Library calls

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


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(3x) 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:

       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.)


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

       In this implementation

          wnoutrefresh
               returns  ERR if the window pointer is null, or if the window is
               really a pad.

          wredrawln
               return ERR if the associated call to touchln returns ERR.


NOTES

       refresh and redrawwin may be implemented as macros.


PORTABILITY

       X/Open Curses Issue 4 describes these functions.  It specifies no error
       conditions for them.

       SVr4 describes a successful return value  only  as  "an  integer  value
       other than ERR".

       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), curs_variables(3x)

ncurses 6.5                       2025-01-18                  curs_refresh(3x)