Bug#798160: Bogus touch events and coords

[Manuel A. Fernandez Montecelo]

Hello Michael,

2015-09-06 11:34 GMT+01:00 Michael Heinemann <reported at heine.so>:
> Package: libsdl1.2debian
> Version: 1.2.15-10
>
> I'm using pygame to build a touch interface on my raspberry pi. When using
> wheezy touch events comming from TSLIB are working fine.
> example:
> [...]
> So I get many more events from SDL and wrong positions.
>
> When I build libsdl 1.2.15 from source I get the expected behaviour. Also
> when installing the wheezy package on jessie the coords are correct.
>
> Problem is also described here:
> https://forums.adafruit.com/viewtopic.php?f=47&t=76169&p=404358

The most important change between the release of libsdl1.2 between
Wheezy and Jessie is this (the rest is mostly administrativia):

  [ Hector Oron ]
  * d/control: remove libts-dev build depends. (Closes: #751766)

This was disabled because the package itself was removed from Debian, see:

  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=751768

So maybe you are getting random coordinates or pygame picks the data
from other source, I don't know.  In any case, if this is indeed
what's causing the problem, there is not much that we can do about it
short of adopting it and reintroducing it to Debian, given that the
other package was dropped.

According to one of the messages in that URL asking for the removal of
tslib from Debian, somebody wanted to step up and maintain it, but
then found out that tslib was superseeded by evdev and dead upstream,
so reintroducing after more than a year out and not in Jessie, doesn't
look like a good idea.


Now, about why it works when you compile from source... Do you have
libts-dev installed (either from Debian or locally in your system)
when compiling yourself from source?  In that case, the reason why it
works when you compile it locally it is probably because it picks up
that library from the system and compiles support for it, whereas the
Debian package from Debian dropped it at compile time and doesn't use
the library even if installed locally.


Another thing is that libsdl1.2 reached end-of-life now.  Apart from
the general message from SDL upstream saying that 1.2 is out and they
will only pay attention to v2, a few days ago all of the bug reports
that we had submitted upstream for the 1.2 branch were closed; they
don't plan to make any updates to it, not even for serious bugs.

So it would be a good idea to migrate projects to use libsdl2, the
support for libsdl1.2 will get no better than it is now and will
gradually degrade.


Cheers.
-- 
Manuel A. Fernandez Montecelo <manuel.montezelo at gmail.com>