[Qtwebengine] Build QtWebEngine on RaspBerry Pi

LongChair69 . longchair69 at gmail.com
Mon Dec 22 15:24:18 CET 2014


I have been trying to figure out how to get a decent performance on RPi,
but i'm coming i think to a dead end until i overlooked something.

my current app requires to use C++ and we would like to avoid any qml stuff
as it's causing some issue with embedding some external components outside
qt world.

As far as i have understood (correct me if i'm wrong) there are 3
possibilities :

- Use QWebView in c++ : this leads to very poor performance on the rpi as
it seems it will not use any hw accelerated backend.
- Use QWebView with qml : this gives good performance, but causes issues to
the other components we have to glue with.
- Use QWebEngine : that was looking like a great thing, but the restriction
of having the need for a QT embedded licence (where it was not the case up
to now) looks like a very bad turn for homebrew developpers. Most Raspberry
Pi applications are free and hombrew devs cannot afford Qt embedded version
for community development.

So did i miss something in my experimentations or am i coming to a dead end
?

How can i achieve both performance, keep c++ without having to get qt
embedded ?

Any thoughts / comments are welcome ! :)

2014-11-19 13:41 GMT+01:00 Florian Bruhin <me at the-compiler.org>:

> * LongChair69 . <longchair69 at gmail.com> [2014-11-19 13:31:08 +0100]:
> > Ok i gave it a shot with QtGraphicsWebview and the simple sample below :
> >
> > [...]
> >
> > the url used is a small site to test css transforms with / without
> > acceleration.
> > given the speed i'm hitting on this sample, it doesn't looks like it is
> > using any HW acceleration.
> >
> > Is there anything that i did wrong in the sample above, or any suggestion
> > that  would explain it's not hitting hw ?
>
> I've not tried QGraphicsWebView myself yet so I'm only guessing, but
> maybe you need to call setViewport on the QGraphicsView with a
> QGLWidget?
>
> From http://qt-project.org/doc/qt-5/qgraphicsview.html :
>
>     By default, QGraphicsView provides a regular QWidget for the
>     viewport widget. You can access this widget by calling viewport(),
>     or you can replace it by calling setViewport(). To render using
>     OpenGL, simply call setViewport(new QGLWidget). QGraphicsView
>     takes ownership of the viewport widget.
>
> The blog post I linked before ([1]) alsop suggests this:
>
>     - Setting the QGraphicsView’s viewportUpdateMode to
>       BoundingRectViewportUpdate
>
> Florian
>
> [1]
> http://blog.qt.digia.com/blog/2010/05/17/qtwebkit-now-accelerates-css-animations-3d-transforms/
>
> --
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