curs_refresh(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(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 screen:

       •   a physical screen, describing what is actually on the screen,

       •   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 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.

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

               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 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

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