[css-pseudo] Geometry methods for CSSPseudoElement

[danielsakhapov]

Not an issue, but rather a discussion about support for geometry methods (e.g. getBoundingClientRect()) for CSSPseudoElement?

One use case is an ability to getBoundingClientRect() for old and new view transitions and do something about it.

@bramus

[bramus]

I’d definitely be in favor of this, exactly for the use case you mention. This would also be useful for other (tree-abiding) pseudos such as the carousel ones.

In #11559 I listed the following:

• Add (only some?) of these extensions to Element from cssom-view also to CSSPseudoElement
• If not all, then at least these would be needed:

  partial interface CSSPseudoElement {
    DOMRectList getClientRects();
    [NewObject] DOMRect getBoundingClientRect();
  }

• For reference: The CSSPseudoElement is already defined to include the GeometryUtils mixin.