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30 * @Id: curs_refresh.3x,v 1.10 2001/11/03 18:57:12 tom Exp @
34 <TITLE>curs_refresh 3x</TITLE>
35 <link rev=made href="mailto:bug-ncurses@gnu.org">
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39 <H1>curs_refresh 3x</H1>
42 <!-- Manpage converted by man2html 3.0.1 -->
46 <STRONG>doupdate</STRONG>, <STRONG>redrawwin</STRONG>, <STRONG>refresh</STRONG>, <STRONG>wnoutrefresh</STRONG>, <STRONG>wredrawln</STRONG>,
47 <STRONG>wrefresh</STRONG> - refresh <STRONG>curses</STRONG> windows and lines
51 <H2>SYNOPSIS</H2><PRE>
52 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
54 <STRONG>int</STRONG> <STRONG>refresh(void);</STRONG>
55 <STRONG>int</STRONG> <STRONG>wrefresh(WINDOW</STRONG> <STRONG>*win);</STRONG>
56 <STRONG>int</STRONG> <STRONG>wnoutrefresh(WINDOW</STRONG> <STRONG>*win);</STRONG>
57 <STRONG>int</STRONG> <STRONG>doupdate(void);</STRONG>
58 <STRONG>int</STRONG> <STRONG>redrawwin(WINDOW</STRONG> <STRONG>*win);</STRONG>
59 <STRONG>int</STRONG> <STRONG>wredrawln(WINDOW</STRONG> <STRONG>*win,</STRONG> <STRONG>int</STRONG> <STRONG>beg_line,</STRONG> <STRONG>int</STRONG> <STRONG>num_lines);</STRONG>
63 <H2>DESCRIPTION</H2><PRE>
64 The <STRONG>refresh</STRONG> and <STRONG>wrefresh</STRONG> routines (or <STRONG>wnoutrefresh</STRONG> and
65 <STRONG>doupdate</STRONG>) must be called to get actual output to the ter-
66 minal, as other routines merely manipulate data struc-
67 tures. The routine <STRONG>wrefresh</STRONG> copies the named window to
68 the physical terminal screen, taking into account what is
69 already there to do optimizations. The <STRONG>refresh</STRONG> routine is
70 the same, using <STRONG>stdscr</STRONG> as the default window. Unless
71 <STRONG>leaveok</STRONG> has been enabled, the physical cursor of the ter-
72 minal is left at the location of the cursor for that win-
75 The <STRONG>wnoutrefresh</STRONG> and <STRONG>doupdate</STRONG> routines allow multiple
76 updates with more efficiency than <STRONG>wrefresh</STRONG> alone. In
77 addition to all the window structures, <STRONG>curses</STRONG> keeps two
78 data structures representing the terminal screen: a physi-
79 cal screen, describing what is actually on the screen, and
80 a virtual screen, describing what the programmer wants to
83 The routine <STRONG>wrefresh</STRONG> works by first calling <STRONG>wnoutrefresh</STRONG>,
84 which copies the named window to the virtual screen, and
85 then calling <STRONG>doupdate</STRONG>, which compares the virtual screen
86 to the physical screen and does the actual update. If the
87 programmer wishes to output several windows at once, a
88 series of calls to <STRONG>wrefresh</STRONG> results in alternating calls
89 to <STRONG>wnoutrefresh</STRONG> and <STRONG>doupdate</STRONG>, causing several bursts of
90 output to the screen. By first calling <STRONG>wnoutrefresh</STRONG> for
91 each window, it is then possible to call <STRONG>doupdate</STRONG> once,
92 resulting in only one burst of output, with fewer total
93 characters transmitted and less CPU time used. If the <EM>win</EM>
94 argument to <STRONG>wrefresh</STRONG> is the global variable <STRONG>curscr</STRONG>, the
95 screen is immediately cleared and repainted from scratch.
97 The phrase "copies the named window to the virtual screen"
98 above is ambiguous. What actually happens is that all
99 <EM>touched</EM> (changed) lines in the window are copied to the
100 virtual screen. This affects programs that use overlap-
101 ping windows; it means that if two windows overlap, you
102 can refresh them in either order and the overlap region
103 will be modified only when it is explicitly changed. (But
104 see the section on <STRONG>PORTABILITY</STRONG> below for a warning about
105 exploiting this behavior.)
107 The <STRONG>wredrawln</STRONG> routine indicates to <STRONG>curses</STRONG> that some screen
108 lines are corrupted and should be thrown away before any-
109 thing is written over them. It touches the indicated
110 lines (marking them changed). The routine <STRONG>redrawwin</STRONG>()
111 touches the entire window.
115 <H2>RETURN VALUE</H2><PRE>
116 Routines that return an integer return <STRONG>ERR</STRONG> upon failure,
117 and <STRONG>OK</STRONG> (SVr4 only specifies "an integer value other than
118 <STRONG>ERR</STRONG>") upon successful completion.
123 Note that <STRONG>refresh</STRONG> and <STRONG>redrawwin</STRONG> may be macros.
127 <H2>PORTABILITY</H2><PRE>
128 The XSI Curses standard, Issue 4 describes these func-
131 Whether <STRONG>wnoutrefresh()</STRONG> copies to the virtual screen the
132 entire contents of a window or just its changed portions
133 has never been well-documented in historic curses versions
134 (including SVr4). It might be unwise to rely on either
135 behavior in programs that might have to be linked with
136 other curses implementations. Instead, you can do an
137 explicit <STRONG>touchwin()</STRONG> before the <STRONG>wnoutrefresh()</STRONG> call to
138 guarantee an entire-contents copy anywhere.
142 <H2>SEE ALSO</H2><PRE>
143 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>
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