Add blurred background

[lenemter]

Closes https://github.com/elementary/greeter/pull/358 Closes https://github.com/elementary/greeter/pull/623

Background code was copied from Gala

[vjr]

I tried this branch and it works well for me, so thumbs up from my side. Hopefully this is reviewed/merged :-)

[vjr]

I tried this branch and it works well for me, so thumbs up from my side. Hopefully this is reviewed/merged :-)

Scratch that! This PR seems to break/interfere with the "fade in" PR #697 recently merged. I was looking at a problem on my machine (with AMD RX580 GPU on OS 7.1 daily) with the fade-in being all noise/garbled but only the wallpaper/background, the other elements (ui_group) fade-in properly. I have not yet tested with OS8 ISO.

[lenemter]

@vjr Oops, I'll fix the fade-in animation as soon as I can

[danirabbit]

@vjr since we reverted the fade in for now, does this still break for you?

[vjr]

@danirabbit yes the blank screen issue is still present.

I just now tested on an updated os8 install showing greeter version 7.0.0 r1550 pkg96 daily ubuntu8.1

Same issue after building and installing this branch so I don't think it was the fade-in PR so hopefully it will return in some form because it's cool.

My bad if I misguided y'all with my recent comments about the fadein causing artefacts which was occurring only on my older PC with an AMD RX 580 GPU.

[vjr]

Okay I just tested this branch with one change to move the Gtk.init call a few lines lower in src/Application.vala like was done in the fade in PR and it fixes the blank screen issue.

[lenemter]

@danirabbit I fixed panel contrast here. I'll prepare a branch for syncing the transparency setting later