Re: [RP] Re: ncurses issues

[John Meacham]

Also be sure to start screen with the '-U' option if you are in a
unicode locale and have a unicode enabled terminal. (mostly the case
nowadays). to find out if that is the case, check if $LANG ends with
UTF-8. not all versions of screen can autodetect this and it can cause
terminal corruption when using non ascii drawing characters.
        John

On Mon, Jul 14, 2003 at 07:50:21PM +0200, Nikolai :: lone-star :: Weibull wrote:
> On Thu, Jul 10 2003, Nikolai :: lone-star :: Weibull wrote something 
> resembling:
> > Hi.  Has anyone ever experienced screen display corruption when running
> > ncurses based applications using line-drawing characters?  An example
> > that (sometimes) produces this behavior is:
> >     xterm -> screen -> raggle/giFTcurs
> > and after switching from it to another (full-sized) window and back the
> > display will be all corrupted, with almost all characters replaced with
> > really-low-ascii characters (i.e. the characters 0 through 12) (like the
> > hearts, clubs, spades, and diamonds card characters).
> >
> > hope my problem is somewhat clear, and a solution is at hand,
> >     nikolai
> >
> gotta love replies to self ;-):
> anyway, i've been investigating and have found a solution.
> 
> The Problem:
>       It seems that screen stores the output of (n)curses applications
>       incorrectly in the scrollback buffer/window buffer/or whatever
>       you prefer to call it.  It stores the 'enter alternate character
>       set'/'exit alternate character set' escape sequences used by
>       (n)curses to draw the line characters incorrectly.  The
>       sequences (for screen) are ^N and ^O (alternate character set use
>       is enabled by the \E(B\E)0) sequence) in the terminfo database.
>       And this is what applications use.  The scrollback buffer,
>       however, stores the enter/exit sequences as \E(0 and \E(B.  This
>       is, at least, what is stored in the paste buffer when the
>       scrollback buffer is copied (^A g SPACE G $ >) and written to a
>       file (^A : writebuf curses-corruption.output).  When moving
>       between windows the display needs to be updated, and thus the
>       contents of the scrollback buffer is written to the terminal,
>       which gets the incorrect enter/exit sequences which, as many
>       have noticed, totally mess up your display.  I assume this is
>       the problem at least, since sending the escape sequences 'by
>       hand' (printf '\e(0' or printf '\e(B' at a shell prompt) to the
>       terminal has the same effect.
> 
> The Solution:
>       Simply remove the 'enacs', 'rmacs', 'smacs' entries from the
>       screen terminfo definition and recompile it with 'tic'.  This,
>       of course, will only work if your font supports line drawing
>       characters without a character set switch.
> 
> hope this helps,
>       nikolai
> 
> P.S.
> To the ratpoison people: A similar question was asked on your list; hope
> this answer helps.
> D.S.
> 
> --
> ::: name: Nikolai Weibull    :: aliases: pcp / lone-star       :::
> ::: born: Chicago, IL USA    :: loc atm: Gothenburg, Sweden    :::
> ::: page: www.pcppopper.org  :: fun atm: gf,lps,ruby,php,war3  :::
> main(){printf(&linux["\021%six\012\0"],(linux)["have"]+"fun"-97);}
> 
> 
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John Meacham - California Institute of Technology, Alum. - address@hidden
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