Re: ncurses screen corruption and terminals
On Sunday 12 June 2016 17:13:19 Henrique de Moraes Holschuh wrote:
> On Sun, 12 Jun 2016, Gene Heskett wrote:
> > On Sunday 12 June 2016 00:09:54 Joe Pfeiffer wrote:
> > > cbannister@slingshot.co.nz writes:
> > > > On Sat, Jun 11, 2016 at 10:04:27PM -0500, David Wright wrote:
> > > > It seems obvious to me, he's talking about screen corruption.
> > > > Gene, Is this when you close it down?
> > >
> > > He might be, except I've never seen screen corruption when running
> > > aptitude.
> >
> > And I have never not seen it. On several different mother boards,
> > and probably 2x the video cards. If there is a difference, I've not
> > a clue.
>
> Screen corruption on ncurses (or, for that matter, slang) applications
> are almost always related to your terminal, and how good its terminal
> emulation (you know, the _critical_, raison-d'être function of a
> terminal program) actually is. And how high-quality, up-to-date its
> terminfo data is (which is just as important as a non-buggy terminal
> emulation engine in practice).
>
> ncurses or slang applications, such as "aptitude", will use the
> terminfo database to come up with the bitstreams it has to send to the
> terminal to paint the screen. The terminal emulation engine has to
> process these properly. If the app is buggy, or the terminal
> emulation engine and terminfo bitstream don't match exactly right
> (i.e. either is buggy, or there are any incompatibilities between
> them), the result is not going to be correct.
>
> Getting all this to work properly is still is a problem in 2016. If I
> take the words of the xterm and ncurses upstream maintainer at face
> value -- which I am inclined to do, because he really knows what he is
> talking about although it is certainly possible he might have outdated
> information -- none of KDE, GNOME, or Debian is doing it right (I
> don't have the time to learn enough about the really low-level details
> to verify or act on this information ATM).
>
> I can attest that Debian jessie's Konsole doesn't work quite right in
> every situation with the "TERM=xterm" and Debian's terminfo, for
> example.
>
>
> If you want to peek at the mess, read this:
> http://invisible-island.net/ncurses/ncurses.faq.html#which_terminfo
>
> and this:
> http://invisible-island.net/xterm/
>
> this is enlightening:
> http://invisible-island.net/xterm/xterm.faq.html
>
> and so is this:
> https://bugs.kde.org/show_bug.cgi?id=145977
>
>
> Not to pick on KDE's Konsole terminal emulator, either: Gnome's is not
> supposed to be any better from the information in the pages above.
>
> Fixing it is not easy, either, due to the way terminal emulator +
> terminfo (which is *local* to the remote system when using a remote
> terminal) works. Including what happens when the remote system does
> NOT have a terminal entry for, e.g. TERM=xterm-debian-fix01 :-)
>
> As for "mc", apparently it is a special beast in its own right and it
> is part of the problem: supposedly, it has so many workarounds for
> broken terminals and terminfo that said workarounds get in the way of
> fixing things properly.
I don't doubt that for a millisecond, mc has been around for north of 30
years I believe, actually dateing back to dos-2.0 days or before. Its
one of those cases where if one fix was removed, the sound of oxen being
gored could be heard from every diehard oldtimer still sucking air
regularly. And I would likely be as loud as anyone as I am "one of
those oldtimers". But I didn't come to linux from the dos world, I came
up from os9 on the trs-80 color computer, to amigados (from 1.3 to 3.9),
so I was a bit late throwing a leg into the linux boat. Every one of
those was multitasking, and os9, now nitros9, was multiuser from the
gitgo. So my mind is not contaminated with a very big load of winders
experience, I don't even allow it on the premises unless its somebody
else's and they've cranked an arm a couple turns to convince me I should
look at their toy.
My biggest problem today is a poor short term memory. That I am told by
reputable medics is to be expected, considering the number of calendars
pulled off the nail in the kitchen & replaced with fresh ones. :(
Cheers Henrique, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>
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