[RP] Re: ncurses issues

[Nikolai :: lone-star :: Weibull]

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);}