[Development] Removing the global static QObject from QPixmapCache

[Konstantin Ritt]

Recreating QGuiApplication is not a common case, ever.
Plus no one said the QPixmap cache would be shared across QGuiApplication
instances. I don't think that was the intention. In fact that could be used
to access some data of another "run" meant to be destroyed/erased/forgotten.

Using QThreadStorage or at least qAddPostRoutine() sounds like a correct
solution.


Regards,
Konstantin


вс, 30 мая 2021 г. в 14:04, Giuseppe D'Angelo via Development <
development at qt-project.org>:

> Hi,
>
> On 30/05/2021 07:28, Sze Howe Koh wrote:
> >
> > So, I propose replacing QGlobalStatic<QPMCache> with
> > QPointer<QPMCache> as a simple self-cleaning singleton, and replacing
> > access to the global variable with QPMCache::instance():
>
> I'd tend to agree with idea, but not with the specific solution. You may
> want
>
> 1) to keep the cache alive across multiple QGA::exec() invocations,
> 2) to destroy it only when QGA gets destroyed,
> 3) to recreate it if QGA itself gets recreated.
>
> A very simple solution is to make the cache a member of QGA(P), create
> it lazily if needed (like Q_G_S does; but I've got the funny feeling
> that the pixmap cache is used in 100% Qt apps, so maybe that's not even
> needed), and kill it in ~QGA.
>
> > I believe this approach should also take care of the ancient QTBUG-21807
> [5]
>
> This has already been fixed, actually, in 5.0:
>
> >
> https://github.com/qt/qtbase/commit/6615dc1370300188f2979fb2c6b8eaa6049d5824
>
>
> Thanks,
> --
> Giuseppe D'Angelo | giuseppe.dangelo at kdab.com | Senior Software Engineer
> KDAB (France) S.A.S., a KDAB Group company
> Tel. France +33 (0)4 90 84 08 53, http://www.kdab.com
> KDAB - The Qt, C++ and OpenGL Experts
>
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