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| .\" $Id: curs_refresh.3x,v 1.25 2022/02/12 20:05:11 tom Exp $ |
| .TH curs_refresh 3X "" |
| .ie \n(.g .ds `` \(lq |
| .el .ds `` `` |
| .ie \n(.g .ds '' \(rq |
| .el .ds '' '' |
| .de bP |
| .ie n .IP \(bu 4 |
| .el .IP \(bu 2 |
| .. |
| .na |
| .hy 0 |
| .SH NAME |
| \fBdoupdate\fP, |
| \fBredrawwin\fP, |
| \fBrefresh\fP, |
| \fBwnoutrefresh\fP, |
| \fBwredrawln\fP, |
| \fBwrefresh\fP \- refresh \fBcurses\fP windows and lines |
| .ad |
| .hy |
| .SH SYNOPSIS |
| \fB#include <curses.h>\fP |
| .sp |
| \fBint refresh(void);\fP |
| .br |
| \fBint wrefresh(WINDOW *\fIwin\fB);\fR |
| .br |
| \fBint wnoutrefresh(WINDOW *\fIwin\fB);\fR |
| .br |
| \fBint doupdate(void);\fP |
| .sp |
| \fBint redrawwin(WINDOW *\fIwin\fB);\fR |
| .br |
| \fBint wredrawln(WINDOW *\fIwin\fB, int \fIbeg_line\fB, int \fInum_lines\fB);\fR |
| .br |
| .SH DESCRIPTION |
| .SS refresh/wrefresh |
| The \fBrefresh\fP and \fBwrefresh\fP routines (or \fBwnoutrefresh\fP and |
| \fBdoupdate\fP) must be called to get actual output to the terminal, |
| as other routines merely manipulate data structures. |
| The routine \fBwrefresh\fP copies |
| the named window to the \fIphysical screen\fP, |
| taking into account what is already there to do optimizations. |
| The \fBrefresh\fP routine is the |
| same, using \fBstdscr\fP as the default window. |
| Unless \fBleaveok\fP has been |
| enabled, the physical cursor of the terminal is left at the location of the |
| cursor for that window. |
| .SS wnoutrefresh/doupdate |
| .PP |
| The \fBwnoutrefresh\fP and \fBdoupdate\fP routines allow multiple updates with |
| more efficiency than \fBwrefresh\fP alone. |
| In addition to all the window |
| structures, \fBcurses\fP keeps two data structures representing the terminal |
| screen: |
| .bP |
| a \fIphysical screen\fP, describing what is actually on the screen, and |
| .bP |
| a \fIvirtual screen\fP, describing what the programmer wants to have on the screen. |
| .PP |
| The routine \fBwrefresh\fP works by |
| .bP |
| first calling \fBwnoutrefresh\fP, |
| which copies the named window to the \fIvirtual screen\fP, and |
| .bP |
| then calling \fBdoupdate\fP, which compares |
| the \fIvirtual screen\fP to the \fIphysical screen\fP |
| and does the actual update. |
| .PP |
| If the programmer wishes to output several windows at once, a series |
| of calls to \fBwrefresh\fP results in alternating calls to \fBwnoutrefresh\fP |
| and \fBdoupdate\fP, causing several bursts of output to the screen. |
| By first |
| calling \fBwnoutrefresh\fP for each window, it is then possible to call |
| \fBdoupdate\fP once, resulting in only one burst of output, with fewer total |
| characters transmitted and less CPU time used. |
| .PP |
| If the \fIwin\fP argument to |
| \fBwrefresh\fP is the \fIphysical screen\fP |
| (i.e., the global variable \fBcurscr\fP), |
| the screen is immediately cleared and repainted from scratch. |
| .PP |
| The phrase \*(``copies the named window |
| to the virtual screen\*('' above is ambiguous. |
| What actually happens is that all \fItouched\fP (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 \fBPORTABILITY\fP below for a warning about |
| exploiting this behavior.) |
| .SS wredrawln/redrawwin |
| .PP |
| The \fBwredrawln\fP routine indicates to \fBcurses\fP 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 \fBredrawwin\fP touches the entire window. |
| .SH RETURN VALUE |
| Routines that return an integer return \fBERR\fP upon failure, and \fBOK\fP |
| (SVr4 only specifies "an integer value other than \fBERR\fP") upon successful |
| completion. |
| .PP |
| X/Open does not define any error conditions. |
| In this implementation |
| .RS 3 |
| .TP 5 |
| \fBwnoutrefresh\fP |
| returns an error |
| if the window pointer is null, or |
| if the window is really a pad. |
| .TP 5 |
| \fBwredrawln\fP |
| returns an error |
| if the associated call to \fBtouchln\fP returns an error. |
| .RE |
| .SH NOTES |
| Note that \fBrefresh\fP and \fBredrawwin\fP may be macros. |
| .SH PORTABILITY |
| The XSI Curses standard, Issue 4 describes these functions. |
| .PP |
| Whether \fBwnoutrefresh\fP 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 \fBtouchwin\fP before the |
| \fBwnoutrefresh\fP call to guarantee an entire-contents copy anywhere. |
| .SH SEE ALSO |
| \fBcurses\fP(3X), |
| \fBcurs_outopts\fP(3X) |
| \fBcurs_variables\fP(3X). |