Incorrect thumbnail size and flicker in artist view

[Michi Henning]

Use the attached song collection for testing. Drop into the Music folder and wait for mediascanner to settle down. (Use top to see when indexing is complete.)

Now start the music app. (It takes a looong time to start.) Go to the artist view. Run

gsettings set com.canonical.Unity.Thumbnailer log-level 2
tail -f ~phablet/.cache/upstart/dbus.log

Scroll down slowly for about twenty screens. Wait until all the thumbnails have been retrieved. (No more activity in dbus.log indicates that the thumbnailer has finished responding to all the requests.)

Scroll back up to the top.

Now scroll down at various speeds. There is a strange flicker on many thumbnails. It looks like they are needlessly redrawn.
Also, the trace in dbus.log shows that the thumbnails that are being asked for are 512 in size, even though the actual display size looks more like 200.

I'm not sure whether that causes the flicker. It might be because the UI is forced to re-scale the thumbnails?

It would be far more efficient to ask for thumbnails at the size they are actually needed instead. For one, that would avoid the need to re-scale and save battery. But it also would make the cache far more effective. (A 512 thumbnail is about 5 (!) times larger than a 200 thumbnail.)

[Michi Henning (michihenning)]

BTW, this is with the latest (2.3.964) version of the music app.