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Re: lib/41223: libcurses: curs_set and move do not cause refresh on getch
The following reply was made to PR lib/41223; it has been noted by GNATS.
From: Jed Davis <jld%panix.com@localhost>
Subject: Re: lib/41223: libcurses: curs_set and move do not cause refresh
Date: Thu, 7 May 2009 22:18:39 -0400
On Tue, Apr 21, 2009 at 12:45:02PM +0000, Brett Lymn wrote:
> I do not think this is the correct thing to do. It is unacceptable to
> force a refresh of the window for every character as this may mean, in
> some very dumb terminal cases, a redraw of the screen.
Oh; I'd assumed that libcurses would be able to avoid unnecessary
redrawing even on dumber terminals.
I'd also assumed that most getch()es would require a refresh anyway, but
now that I've done a bit of testing with an instrumented libcurses I see
that this isn't necessarily so.
> A peek at the Open Solaris curses code shows they perform a fflush on
> the output file descriptor after the tput - I think that would be a
> better solution.
The other thing that OpenSolaris curses does is for wmove to set a bit
in the per-WINDOW flags field, which causes a refresh on the next getch.
In the application where I noticed this issue, just making curs_set do
the fflush and not also taking care of the wmove causes the cursor to be
visible and in the wrong place.
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