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man pages section 3: Curses Library Functions

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Updated: Thursday, June 13, 2019
 
 

wredrawln(3CURSES)

Name

curs_refresh, refresh, wrefresh, wnoutrefresh, doupdate, redrawwin, wredrawln - refresh curses windows and lines

Synopsis

cc [ flag ... ] file ... –lcurses [ library ... ]
#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

The refresh() and wrefresh() routines (or wnoutrefresh() and doupdate()) must be called to get any output on 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 in order to do optimizations. The refresh() routine is the same, using stdscr as the default window. Unless leaveok() 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, 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 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 global variable curscr, the screen is immediately cleared and repainted from scratch.

The redrawwin() routine indicates to curses that some screen lines are corrupted and should be thrown away before anything is written over them. These routines could be used for programs such as editors, which want a command to redraw some part of the screen or the entire screen. The routine redrawln() is preferred over redrawwin() where a noisy communication line exists and redrawing the entire window could be subject to even more communication noise. Just redrawing several lines offers the possibility that they would show up unblemished.

Return Values

All routines return the integer ERR upon failure and an integer value other than ERR upon successful completion.

Attributes

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
MT-Level
Unsafe

See Also

curs_outopts(3CURSES), curses(3CURSES), attributes(7)

Notes

The header <curses.h> automatically includes the headers <stdio.h> and <unctrl.h>.

Note that refresh() and redrawwin() may be macros.