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Miscellaneous Library Functions curs_refresh(3X)

NAME

doupdate, redrawwin, refresh, wnoutrefresh, wredrawln,

wrefresh - refresh curses windows and lines

SYNOPSIS

#include

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

The refresh and wrefresh routines (or wnoutrefresh and doup-

date) 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 terminal 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 en-

abled, the physical cursor of the terminal is left at the location of the cursor for that window.

The wnoutrefresh and doupdate routines allow multiple up-

dates with more efficiency than wrefresh alone. In addition

to all the window structures, curses keeps two data struc-

tures 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 pro-

grammer 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 win-

dow, 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 global variable curscr, the screen is im-

mediately 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 vir-

tual screen. This affects programs that use overlapping

windows; it means that if two windows overlap, you can re-

SunOS 5.10 Last change: 1

Miscellaneous Library Functions curs_refresh(3X)

fresh 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 any-

thing is written over them. It touches the indicated lines

(marking them changed). The routine redrawwin() touches the

entire window. RETURN VALUE 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 imple-

mentation 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 The XSI Curses standard, Issue 4 describes these functions.

Whether wnoutrefresh() copies to the virtual screen the en-

tire contents of a window or just its changed portions has

never been well-documented in historic curses versions (in-

cluding 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)

SunOS 5.10 Last change: 2




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