869129 - Need backgroundPosition OMTA fastpath

Status: NEW

(Core :: Layout, defect)

Description

[Benoit Girard (:BenWa)]

CSS animation + backgroundPosition let css animation perform gif/sprite sheet effects. Currently backgroundPosition causes invalidation and is generally very expensively. Jeff says we have hit this in B2G and I hit it this weekend designing a DOM game using sprite sheets:

https://github.com/bgirard/ToJAM2013/commit/c504a5fb9f864ec37443b67a2868ef0f3c20e891

STR:
1) Open game.html
2) Use WASD to move, go near the edge of the level to see spinning pyramids.

Because they use backgroundPosition to animate the sprite sheets the performance is very poor.

If we created a backgroundPosition OMTA fast path for these we could support these use case very efficiently.

Comment 1

[David Zbarsky (:dzbarsky)]

I can probably look at this in a few days.