[WLR Scene] Add blur

[ErikReider]

Depends on #30

Todo:

• Figure out the best way for the compositor to know when to rerender the optimized blur
• tinywl example for optimized blur

[ErikReider]

An optimized blur example in tinywl wouldn't really make it that tiny and simple anymore, so skipping that :)

[WillPower3309]

An optimized blur example in tinywl wouldn't really make it that tiny and simple anymore, so skipping that :)

Understandable, but do you mind running me through what's required on the comp side for getting this to work in scene? I'm following it along but a summary may be helpful

My thinking here is that one of the main goals of scene is for compositors to easily leverage our effects in very few LOC

[ErikReider]

do you mind running me through what's required on the comp side for getting this to work in scene?

So the optimized blur is a new scene node that should be inserted between regular scene trees, which would be between bottom and workspace in sways use-case. The comp is responsible for resizing the node to the desired size, which in most use-cases would be the monitor's size and coordinates.

The comp is also responsible for redrawing the optimized blur by marking it as “dirty”. Sway currently redraws the blur when any background or bottom layer surface commits.

So actually implementing it in a fully fledged comp doesn't require that many LOC, but adding an example in TinyWL would require adding extra non-blur related code (the extra layers and a good way of showing off the optimized blur)