Drop support for Stretch and Buster

[heuer]

Trixie is just around the corner, there is no point in continuing to support such old distributions.

I will make a hard cut in the develop branch.

Until the develop branch has stabilized, the setup from the master branch can still be used, if it still works.

[PeterDHabermehl]

I absolutely agree, thanks.
There is one major issue, though. @harbaum reported that he was never able to fix the TouchStyle.py on-screen keyboard for (Py)Qt5.
Other than that there would be no issue to move on to Qt5. Or should we set up the TxPi with legacy Qt4? I don't think so.

[harbaum]

Qt5 has a completely different way of dealing with virtual keyboards which I never fully understood.

In theory we could probably ignore that altogether if we make sure that text input is always done via some custom widget. The only downside would IMHO be that existing app that use the original input widgets like qlineedit would not have touch support and would have to be slightly modified.

[harbaum]

Here's the part in question:

https://github.com/harbaum/TouchUI/blob/bc9dc4a56305857d9a18c4cee99bc52f2eb5803d/touchui/TouchStyle.py#L808-L810

This needs to get replaced somehow.

[heuer]

I'll see if you can still get Qt4 somewhere.

It might have to be compiled during installation, e.g. from here https://download.qt.io/archive/qt/4.8/4.8.7/qt-everywhere-opensource-src-4.8.7.tar.gz

I have to see what's less work. ;)

First of all, I'm interested in maintaining the status quo.

[heuer]

It might also be possible to use the Trinity project: https://wiki.trinitydesktop.org/Preliminary_Stable_Builds

The project still releases Qt4 for current Debian versions. But I don't know if it still runs under the Qt4 namespace or a fork of Qt4 under a different name. The packages have an additional "t" in the name, so it could be that the namespace is different: https://mirror.ppa.trinitydesktop.org/trinity/deb/trinity-sb/pool/main-r14/p/pytqt/

But this could easily be fixed.

[heuer]

Looking ahead, it would probably make more sense to adapt TouchUI. Qt5 reaches EOL in May (https://www.qt.io/blog/qt-5.15-extended-support-for-subscription-license-holders), and the upcoming version of Debian will likely be the last with rudimentary support for Qt5 (https://wiki.debian.org/PkgQtKde/TrixieReleasePlans).