NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PORTABILITY | SEE ALSO | COLOPHON

curs_refresh(3X)                                            curs_refresh(3X)

NAME         top

       doupdate, redrawwin, refresh, wnoutrefresh, wredrawln, wrefresh -
       refresh curses windows and lines

SYNOPSIS         top

       #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         top

   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 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.

   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 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         top

       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         top

       Note that refresh and redrawwin may be macros.

PORTABILITY         top

       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         top

       curses(3X), curs_outopts(3X) curs_variables(3X).

COLOPHON         top

       This page is part of the ncurses (new curses) project.  Information
       about the project can be found at 
       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have a
       bug report for this manual page, send it to
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                                                            curs_refresh(3X)