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[css-contain] content-visibility and SVG #9466
Description
From my current interpretation content-visibility does not apply to most SVG elements since content-visibility applies to
"elements for which [size containment] can apply" (https://drafts.csswg.org/css-contain/#content-visibility)
and (size) contain has a special rule about applying to svg:
"In addition, in the case of [SVG2], the contain property only applies to svg elements that have an associated CSS layout box."
(https://drafts.csswg.org/css-contain/#contain-applies)
So, would that be just outer <svg> and <foreignObject> elements?
I am willing to write some WPT tests for this since I don't think this is actually tested on SVG elements at this time.
Activity
rwlbuis commentedon Oct 16, 2023
I added a test on an SVG element that has no associated CSS layout box (<g>):
web-platform-tests/wpt#42552
rwlbuis commentedon Oct 16, 2023
@vmpstr what is your interpretation? Also feel free to add more people :)
vmpstr commentedon Oct 16, 2023
This interpretation makes sense to me. Size containment is important for the optimization that c-v makes, so if it doesn't apply, then c-v should also not apply.
To confirm: the spec would not need to change, since it effectively states this, right?
rwlbuis commentedon Oct 18, 2023
Well, one thing I could not find in the specifications is which SVG elements have an associated CSS layout box. Because I kind of know from the implementation to me it sort of is clear, not sure for others.
I realised we do not really test the root <svg>, so I created web-platform-tests/wpt#42594.