1curs_refresh(3X) curs_refresh(3X)
2
6 doupdate, redrawwin, refresh, wnoutrefresh, wredrawln, wrefresh -
7 refresh curses windows and lines
8
10 #include <curses.h>
11 int refresh(void);
13 int wrefresh(WINDOW *win);
14 int wnoutrefresh(WINDOW *win);
15 int doupdate(void);
16 int redrawwin(WINDOW *win);
17 int wredrawln(WINDOW *win, int beg_line, int num_lines);
18
20 The refresh and wrefresh routines (or wnoutrefresh and doupdate) must
21 be called to get actual output to the terminal, as other routines mere‐
22 ly manipulate data structures. The routine wrefresh copies the named
23 window to the physical terminal screen, taking into account what is al‐
24 ready there to do optimizations. The refresh routine is the same, us‐
25 ing stdscr as the default window. Unless leaveok has been enabled, the
26 physical cursor of the terminal is left at the location of the cursor
27 for that window.
28 The wnoutrefresh and doupdate routines allow multiple updates with more
30 efficiency than wrefresh alone. In addition to all the window struc‐
31 tures, curses keeps two data structures representing the terminal
32 screen: a physical screen, describing what is actually on the screen,
33 and a virtual screen, describing what the programmer wants to have on
34 the screen.
35 The routine wrefresh works by first calling wnoutrefresh, which copies
37 the named window to the virtual screen, and then calling doupdate,
38 which compares the virtual screen to the physical screen and does the
39 actual update. If the programmer wishes to output several windows at
40 once, a series of calls to wrefresh results in alternating calls to
41 wnoutrefresh and doupdate, causing several bursts of output to the
42 screen. By first calling wnoutrefresh for each window, it is then pos‐
43 sible to call doupdate once, resulting in only one burst of output,
44 with fewer total characters transmitted and less CPU time used. If the
45 win argument to wrefresh is the global variable curscr, the screen is
46 immediately cleared and repainted from scratch.
47 The phrase "copies the named window to the virtual screen" above is am‐
49 biguous. What actually happens is that all touched (changed) lines in
50 the window are copied to the virtual screen. This affects programs
51 that use overlapping windows; it means that if two windows overlap, you
52 can refresh them in either order and the overlap region will be modi‐
53 fied only when it is explicitly changed. (But see the section on
54 PORTABILITY below for a warning about exploiting this behavior.)
55 The wredrawln routine indicates to curses that some screen lines are
57 corrupted and should be thrown away before anything is written over
58 them. It touches the indicated lines (marking them changed). The rou‐
59 tine redrawwin() touches the entire window.
60
62 Routines that return an integer return ERR upon failure, and OK (SVr4
63 only specifies "an integer value other than ERR") upon successful com‐
64 pletion.
65 X/Open does not define any error conditions. In this implementation
67 wnoutrefresh
69 returns an error if the window pointer is null, or if the
70 window is really a pad.
71 wredrawln
73 returns an error if the associated call to touchln returns
74 an error.
75
77 Note that refresh and redrawwin may be macros.
78
80 The XSI Curses standard, Issue 4 describes these functions.
81 Whether wnoutrefresh() copies to the virtual screen the entire contents
83 of a window or just its changed portions has never been well-documented
84 in historic curses versions (including SVr4). It might be unwise to
85 rely on either behavior in programs that might have to be linked with
86 other curses implementations. Instead, you can do an explicit touch‐
87 win() before the wnoutrefresh() call to guarantee an entire-contents
88 copy anywhere.
89
91 curses(3X), curs_outopts(3X) curs_variables(3X).
92 curs_refresh(3X)