Merge lp:~fboucault/unity-2d/dont_set_colorspec into lp:unity-2d/3.0

[Florian Boucault]

[launcher & panel] Do not call QApplication::setColorSpec that is leading to visual artifacts appearing sometimes.

[Florian Boucault (fboucault)]

Warning: this might not be finished work.

1) We need to see how many people are affected by the bug https://bugs.launchpad.net/unity-2d/+bug/734143
2) We need to find a proper fix for the color banding that the code removed by this MR was supposed to fix (ref: https://bugs.launchpad.net/unity-2d/+bug/674484)

[Florian Boucault (fboucault)]

> Warning: this might not be finished work.
>
> 1) We need to see how many people are affected by the bug
> https://bugs.launchpad.net/unity-2d/+bug/734143

Apparently I am not the only one with these issues.

> 2) We need to find a proper fix for the color banding that the code removed by
> this MR was supposed to fix (ref: https://bugs.launchpad.net/unity-
> 2d/+bug/674484)

Bug is now reopened.

Let's merge that as soon as possible.

[Olivier Tilloy (osomon)]

Disclaimer: I’m running Maverick natively on a Macbook 5.1 with an NVIDIA GeForce 9400M, and I have never observed the issue this merge request is meant to address.

> > Warning: this might not be finished work.
> >
> > 1) We need to see how many people are affected by the bug
> > https://bugs.launchpad.net/unity-2d/+bug/734143
>
> Apparently I am not the only one with these issues.

Do we have more data on who is affected, and how badly? Is it 'only' a bug in the NVIDIA driver, or does it affect other hardware configurations? Such information should be gathered in the bug report.

> > 2) We need to find a proper fix for the color banding that the code removed
> by
> > this MR was supposed to fix (ref: https://bugs.launchpad.net/unity-
> > 2d/+bug/674484)
>
> Bug is now reopened.
>
> Let's merge that as soon as possible.

I may be missing the broader picture, but reading the documentation (http://doc.qt.nokia.com/qapplication.html#setColorSpec), I don’t understand how setting the colour specification to ManyColor could possibly trigger direct rendering issues. This is obviously a bug lower down the stack. Do we have a reference to a similar known issue? Any hope of a fix that doesn’t involve hacks on our side?

Ultimately, it looks to me like a trade-off between getting the colours right on some ARM platforms, or avoiding this black-boxes bug. Do we really want to favour the latter? If so I guess your fix is correct and can be merged (see my disclaimer though).

[Florian Boucault (fboucault)]

Thank you Olivier.

I'll take responsibility for that trade-off.

https://bugs.launchpad.net/unity-2d/+bug/674484 is reopened to deal with the color banding.

=== modified file 'launcher/app/launcher.cpp'
--- launcher/app/launcher.cpp	2011-03-07 14:52:11 +0000
+++ launcher/app/launcher.cpp	2011-03-13 04:12:18 +0000
@@ -55,13 +55,13 @@
 
     /* Forcing graphics system to 'raster' instead of the default 'native'
        which on X11 is 'XRender'.
-       'XRender' defaults to using a TrueColor visual. We mimick that behaviour
-       with 'raster' by calling QApplication::setColorSpec.
+       'XRender' defaults to using a TrueColor visual. We do _not_ mimick that
+       behaviour with 'raster' by calling QApplication::setColorSpec because
+       of a bug where black rectangular artifacts were appearing randomly:
 
-       Reference: https://bugs.launchpad.net/upicek/+bug/674484
+       https://bugs.launchpad.net/unity-2d/+bug/734143
     */
     QApplication::setGraphicsSystem("raster");
-    QApplication::setColorSpec(QApplication::ManyColor);
     Unity2dApplication application(argc, argv);
 
     GnomeSessionClient client(INSTALL_PREFIX "/share/applications/unity-2d-launcher.desktop");

=== modified file 'panel/app/main.cpp'
--- panel/app/main.cpp	2011-03-07 14:52:11 +0000
+++ panel/app/main.cpp	2011-03-13 04:12:18 +0000
@@ -93,13 +93,13 @@
 
     /* Forcing graphics system to 'raster' instead of the default 'native'
        which on X11 is 'XRender'.
-       'XRender' defaults to using a TrueColor visual. We mimick that behaviour
-       with 'raster' by calling QApplication::setColorSpec.
+       'XRender' defaults to using a TrueColor visual. We do _not_ mimick that
+       behaviour with 'raster' by calling QApplication::setColorSpec because
+       of a bug where black rectangular artifacts were appearing randomly:
 
-       Reference: https://bugs.launchpad.net/upicek/+bug/674484
+       https://bugs.launchpad.net/unity-2d/+bug/734143
     */
     QApplication::setGraphicsSystem("raster");
-    QApplication::setColorSpec(QApplication::ManyColor);
     Unity2dApplication app(argc, argv);
     QApplication::setStyle(new Unity2dStyle);