Some infomation about recent Qt5 mouse handling work.

[Jan-Marek Glogowski]

Hi Xuetian,

> I'm just coming from a phoronix post about qt5 work on libreoffice. IOha

> noticed that 
> https://cgit.freedesktop.org/libreoffice/core/commit/?id=1426437be0530a8ba5749c7e76c5ce0e9053af2f 
> mentioned that there're still some issues on touchpad, so I'd just like to
> provides some info about qt5's wheel event since I had fixed a bunch of
> similar issue in KDE some time ago.
> 
> This is because qt5  generates high resolution touchpad event.  The correct
> implementation can be  done by either making use of pixelDelta to do high
> resolution scroll, or using  angleDelta(or delta in qwidget) to trigger a
> "tick" every 120 unit of angle delta. More information can be  found at 
> http://doc.qt.io/qt-5/qml-qtquick-wheelevent.html#angleDelta-prop (it's for
> qml but the information about delta also applies to qwidget).
> 
> An example of "120 per tick" implementation in KDE code base can be found
> at: 
> https://lxr.kde.org/source/frameworks/plasma-framework/src/scriptengines/qml/plasmoid/containmentinterface.cpp#1097
> 
> I guess for this  Qt5 work is still WIP probably doesn't worth a bug report,
> so I'd just ping some one  here.

Thanks for the info. It'll definitely be handy at some time.

I found https://doc.qt.io/qt-5/qwheelevent.html#angleDelta, which even
has a little example and which I kind of copied. The larger problem is
to understand, what the LO VCL event expects.

And you're right; since we still get the basic stuff running, it doesn't
make any sense to open bug reports. I hope something really usable will
be ready for 6.0. Still end of January 2018 seems a short ETA to finish
everything, not even considering any special KF5 handling.

> Regards,

Jan-Marek