[dash] background is not transparent when using Qt with OpenGLES

[Ricardo Salveti]

Currently when using Unity-2D with Qt using the OpenGLES backend, the dash transparency is broken, like described by the following screenshot:
http://people.canonical.com/~rsalveti/unity-2d/unity-2d-cache_dash_background-opengl.png

This bug was already happening before, but the fix for bug 806122 seems that made it worse, like you can see by comparing both screenshots:
1 - http://people.canonical.com/~rsalveti/unity-2d/unity-2d-trunk-opengl.png
2 - http://people.canonical.com/~rsalveti/unity-2d/unity-2d-cache_dash_background-opengl.png

[Ricardo Salveti (rsalveti)]

The device used to reproduce this issue is a pandaboard, using Ubuntu Natty release.

[Ricardo Salveti (rsalveti)]

Using Unity-2d trunk, rev 626.

[Ricardo Salveti (rsalveti)]

Posting Florian's comment about the issue:
Looking at the screenshots, I don't think this patch makes the situation worse: the dash is not transparent in either case. Before the patch its background is plain white, after the patch its background is plain black. I would merge it for the performance improvement and try to fix the transparency issue separately.
I don't have a working device on which I can try various possible fixes with an OpenGL/ES driver. Could you try one thing and see if the transparency works better?

in libunity-2d-private/src/unity2ddeclarativeview.cpp line 61, change:

            setAttribute(Qt::WA_OpaquePaintEvent, true);

into:
            setAttribute(Qt::WA_OpaquePaintEvent, false);

If that does not help, try to add the following line just after:

            glWidget->setAutoFillBackground(true);

[Ricardo Salveti (rsalveti)]

Issue still happening even after doing both changes.

[Lucazade (lucazade)]

may I ask how to enable the opengl backend? I've seen the new option in dconf but doesn't seem to do nothing.
should I install any other packages or anyway to check if opengl backend is really working? thanks

[Alberto Mardegan (mardy)]

@lucazade: that dconf option should work properly, but it's only effective from the next execution of the applications. In other words, you should restart your session in order to see a difference.

[Lucazade (lucazade)]

@thanks Alberto for the info, hope i'm not OT in this bugreport..
I've tried to restart session and to enable this opengl option on a couple of different machines but I can't see any difference in term of speed, also launcher and dash are not trasparent if I don't enable metacity compositor.
I believed opengl accel should give both speed boost and trasparency like a compositor, am I wrong? if necessary I can open a separate bug.