[Qgis-user] QGIS Qt6 Wayland ongoing status

[chris hermansen]

Thanks very much for this detailed authoritative explanation, Nyall.  I
have a couple of specific comments below...

On Wed, Jan 17, 2024 at 10:29 PM Nyall Dawson <nyall.dawson at gmail.com>
wrote:

>
>
> On Thu, 18 Jan 2024 at 13:56, chris hermansen via QGIS-User <
> qgis-user at lists.osgeo.org> wrote:
> >
> > Adam and list,
> >
> > On Wed, Jan 17, 2024 at 5:34 PM Adam Nielsen <a.nielsen at shikadi.net>
> wrote:
> >>
> >> > I have been trying to find a mostly definitive and mostly up-to-date
> >> > conversation about the status of QGIS, Qt6 and Wayland and I'm not
> having
> >> > any luck.
> >>
> >> What's the underlying need for this information?
>
> ... gather round folks, for a truly sorry tale! Here's the definitive(*)
> situation regarding QGIS and wayland.
>
> - Qt 5 based applications do NOT work well under any wayland environment.
> There's fundamental broken functionality, and its functionality which QGIS
> requires. A good example is trying to drag a toolbar or dock panel --
> you'll instantly "break" the application with non functional empty windows.
> - This particular issue HAS been fixed in very recent Qt versions. Read
> all about it here:
> https://blog.david-redondo.de/kde/wayland/qt/2023/08/08/xdg-toplevel-drag.html
> . BUT... this fix ONLY works if the desktop environment supports the fix.
> So you'll also need a very recent KDE release for this to work. Gnome, in
> typical Gnome fashion, have shown no interest in helping out other toolkits
> and implementing this new Wayland protocol and so Qt applications (even
> those built with Qt 6.6+) will still be broken. There's little hope on the
> horizon that Gnome will change their ways, so you'll also need to move to
> KDE and put Gnome in the past. 🤷
>

 It's disappointing to read this as there's clearly a disconnect between
what e.g. QGIS developers are experiencing and what Fedora, Gentoo and
maybe others are saying about Qt5 and Wayland.  For example, this on the
Gentoo Wiki here https://wiki.gentoo.org/wiki/Wayland

For Qt an additional package called dev-qt/qtwayland
> <https://packages.gentoo.org/packages/dev-qt/qtwayland> is required. In
> the Qt Wiki it says: "QtWayland is a Qt 5 module that wraps the
> functionality of Wayland. QtWayland is separated into a client and server
> side. The client side is the wayland platform plugin, and provides a way to
> run Qt applications as Wayland clients. The server side is the QtCompositor
> API, and allows users to write their own Wayland compositors."


And this on Fedora here
https://fedoraproject.org/wiki/Changes/Qt_Wayland_By_Default_On_Gnome

Qt Wayland plugin has been available for a long time, but it hasn't been in
> condition where it could be enabled by default. With Qt 5.12 the state of
> the Wayland plugin is much better and it's becoming more and more reliable.
> It now supports all the needed protocols and has been enabled by default
> for non-Gnome Wayland sessions. With Qt Wayland on Gnome Wayland session we
> need to support CSD, it's actually the only way how decorations are going
> to work in Qt apps right now. Qt Wayland implements basic decorations,
> which really doesn't match Gnome Adwaita theme, therefore there are new CSD
> being implemented as part of QGnomePlatform.

To make Qt applications run natively on Wayland we need to modify Qt 5,
> specifically *qt5-qtbase* module, where we allow the Wayland plugin to be
> used also for Gnome sessions. The new decorations from QGnomePlatform will
> be used automatically once they are fully implemented and updated in
> Fedora.

(the above dated 2019!!!)

> - So let's say you're running KDE, on a distro with a very recent Qt
> version. You'll still need a QGIS build based on Qt 6. That's a heavy work
> in progress at the moment. We're all ACTIVELY working toward that, but it's
> still some time away. You CAN build master versions and get a mostly
> working QGIS Qt6 build, so long as you don't require any Python support,
> that is!
> - Ok, now lets assume you're on KDE, have recent Qt 6 library, have built
> QGIS master with Qt6 support and don't need python/plugins. Yay! Will
> everything work on Wayland? Well, not quite!.. There's still going to be
> broken functionality (such as the color picker not working outside of the
> QGIS application). There's also STILL fundamental missing bits in Wayland
> itself, such as proper restoring of Window locations. Every time QGIS opens
> a new dialog it'll just be thrown on some random screen at some random
> location. There's still no real progress toward that being fixed. Read
> about the sorry state of it here:
> https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/247
>

An exceptionally informative pull request.  I was particularly struck by
this comment:

 Of course you could argue that all of these applications should be
> rewritten from the ground up, but especially in science this is not
> feasible - people will use X11 indefinitely rather than going to Wayland
> with a much degraded user experience.


Maybe it's just me, but I have to think that the lack of a placement
protocol (when X, Windows and OSX all support this) is a design mis-feature
in Wayland, rather than a decision taken to guide the architecture of
future desktop applications...


> So yeah, not a happy situation. At least on the QGIS side we're making
> progress toward Qt 6 compatibility, and that's all we can really do from
> our end.
>

Well as always, extreme thank-yous to all QGIS developers.  And again the
information you provide here is very valuable at least to me, so thanks
again for taking the time to write this!

>
> Nyall
>

[previous stuff deleted]


-- 
Chris Hermansen · clhermansen "at" gmail "dot" com

C'est ma façon de parler.
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