redrawwin(3x) — Linux manual page


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

       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 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, 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

       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

       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

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

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