manpagez: man pages & more
man refresh(3)
Home | html | info | man
curs_refresh(3)                 Library calls                curs_refresh(3)


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 (SVr4
       specifies only "an integer value other than ERR") upon successful
       completion.

       X/Open Curses does not specify 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

       Note that refresh and redrawwin may be macros.


PORTABILITY

       X/Open Curses, 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

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

ncurses 6.5                       2024-04-20                  curs_refresh(3)

ncurses 6.5 - Generated Wed May 1 12:53:35 CDT 2024
© manpagez.com 2000-2024
Individual documents may contain additional copyright information.