[launcher] icons jagged edges during animation

This has been the case for a long time. I believe this regression was introduced when optimizations for low-end hardware were devised, possibly with revision 263.

The same issue for me running 10.10.
daker@daker-desktop:~$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 82845G/GL[Brookdale-G]/GE Chipset Integrated Graphics Device (rev 01)

Olivier is right. The issue does not appear using the x11 backend nor with the opengl backend.

The issue is raster specific and appears only when the radius of the background Rectangle is not 0.

BTW, you guys can easily switch engine by using the -graphicssystem switch on the command line.

e.g.

$ unity-2d-launcher -graphicssystem opengl

This is important for Natty. Need to figure out a way to dynamically determine the appropriate backend to use such that this problem doesn't occur on systems that support it.

The raster backend is the one we are going to use for the foreseeable future, especially for Natty.
The X11 backend is not as fast and not recommended by the Qt developers
The OpenGL backend will not work on all hardware/software configurations. I would like in the future to enable it when possible and for the detection use the code written by Loïc Molinari for Unity 3D.

I believe the cause of the issue has changed from:

"[..] appears only when the radius of the background Rectangle is not 0."

to:

We do not use any background Rectangle anymore but Images instead. I am afraid the fix will not be simple.

We need to investigate possible fixes that don't involve changing the backend.
Can an alternative animation be used that doesn't have this issue?
Are we sure that the color spec change we added for ARM banding is not causing this?

The issue was simply that during the launcher overhaul that landed at revision 388, the 'smooth' property of the Image, Rectangle and Text elements in LauncherItem were lost. Adding them where relevant fixes the issue.