[Development] iMX6 EGLGS 2D (QtWidgets) painting acceleration

[Uwe Rathmann]

On Thu, 30 Aug 2018 14:26:34 +0300, Denis Shienkov wrote:

> Yeah, seems that Qt5 && X11 && 'xcb' backend with the Qwt 6.2 and
> QwtPlotOpenGLCanvas does help a bit. The iMX6 CPU usage now is ~50%
> (instead of previous 100%).

I have been attending one of the Qt roadshows last year in Munich. One of 
the speakers asked the audience which Qt versions they are using:

I didn't have time to count them manually, but my rough estimation was 
that about 30% were still on Qt4. Assuming that almost all of them were 
Qt/Widgets users and there are others in the Qt5 groups I would guess 
that the majority was interested in Qt/Widget applications.

Considering, that Qt/Quick Controls 1 has been given up it is fair to say 
that today the only reasonable option, Qt has to offer for desktop 
applications, is: Qt/Widgets. So to me there is an obvious mismatch 
between where the users are and what Qt development is working on.

Concerning the future of Qt/Widgets I guess almost everyone wants to have 
hardware accelerated options - like what we had with Qt4/X11 or what 
could be done with OpenGL.

The most recent related feature I'm aware of was introducing QOpenGLWidget 
with Qt 5.4. But combining QOpenGLWidget with standard QWidgets is 
unstable - see https://bugreports.qt.io/browse/QTBUG-50916 ).

Furthermore nobody seems to be interested in working on the OpenGL paint 
engine. At least I have no explanation, why bugs like this one https://
bugreports.qt.io/browse/QTBUG-52672 are not being handled over years.
( actually this one is assigned to Gunnar, who is not even active anymore 
).

>From my experience with the QSkinny project I'm tempted to say that it 
would even be possible to implement the Qt/Widgets API on top of Qt/Quick 
core. Of course it wouldn't be exactly the same, but for standard desktop 
applications it should be possible to offer a migration path, that is not 
harder than what we had with Qt3 -> Qt4.

Uwe