[css4-images] element() and compositing layers

This question is more-or-less directed toward the Moz implementors of
-moz-element().

I presume that you have a similar hardware compositing model to us at
WebKit, where some elements establish compositing layers, but not all
of them - each node in the compositing tree may contain multiple
descendants of the node-establisher.

What do you do when a -moz-element() references one of these elements
that aren't the root of a compositing-tree layer?  I can see a few
options:

1. Split apart the layer so that the referenced element establishes a
layer.  (This seems to require either making it a stacking context, or
doing some more advanced trickery.)
2. Do a paint with the existing layer, but do an ancestry check on
each element, skipping painting of those that aren't descendants of
the referenced layer.
3. Draw element() images with a different path than what's used for
normal page rendering.
4. Something else?

~TJ

Received on Friday, 27 July 2012 23:14:02 UTC