[vlc-devel] [PATCH] qt: Prefer XCB over Wayland

Rémi Denis-Courmont remi at remlab.net
Thu Jun 29 18:48:40 CEST 2017

Le torstaina 29. kesäkuuta 2017, 17.17.15 EEST Nicolas Chauvet a écrit :
> > I don't see any rationale why Xlib should have priority over Wayland.
> > Normally, if you have both, you want the later.
> FYI, I've applied this patch in Fedora as it allows Wayland users to
> use vlc under XWayland and circumvent the qt bugs under such
> environment.

That´s not answering the question why X11 should be prioritized over Wayland.

> > The referenced bug alleges Qt bugs in the version of Qt shipped by Fedora.
> > That's not a rationale in the context of this upstream VLC repository.
> Sure, but actually I still fail to understand why the bug is in the qt
> side ? As I have an older vlc snapshot working with the same qt 5.7.1
> that we have in Fedora. (anything later the qt platform detection
> fails).

If the bug means VLC Trac ticket 18383, then it is a limitation of the Qt API 
design. This patch is not fixing the bug. AFAICT, fixing that bug 
intrinsically involves first changing the public Qt API, and *then* adapting 
VLC accordingly.

> I've also checked that no qt patches would be relevant in the vlc
> contribs (only relevant for Windows) and we also have the private
> header  -DQPNI_HEADER=\<5.7.1/QtGui/qpa/qplatformnativeinterface.h\>.
> I understand it can be qt bug, but I fail to see how that's an evidence ?

No, I cannot because it is hard to prove a negative. But so far, I have not 
found any way to try to initialize a Qt GUI application instance, and fail 
safe (to not using Qt) if applicable. As far as I can tell, Qt always aborts 
the process.

> So can you elaborate ?

Not really. If you think that the Qt API is fine and the bug is entirely 
fixable in VLC, please provide a patch. But several developers have tried and 
failed already (including myself).


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