Re: [csswg-drafts] [css-anchor-1] Need ability to say "don't render" when anchor is off-screen (#7758)

> This also fails to be a [valid anchor function](https://drafts.csswg.org/css-anchor-position/#anchor-valid), and thus is ignored.

> In https://github.com/w3c/csswg-drafts/issues/7758#issuecomment-1965540529, we're saying it should hide if any of its anchors are invalid/invisible (and the anchor function doesn't have a fallback).

Does "invalid" mean an anchor function is not a [valid anchor function](https://drafts.csswg.org/css-anchor-position/#anchor-valid)? If yes, should invalid anchor functions like
- `border-width: anchor(top)`
- `top: anchor(left)`
- `top: anchor(top)` without a default anchor

cause the anchored element with `anchors-visible` or `anchors-valid` to hide, instead of being ignored? If we ignore them, then in what conditions an anchored element with `anchors-valid` should hide?

> I'm not sure what this means. Could you elaborate?

I mean whether we should check the two conditions listed under "An absolutely-positioned element query el **needs scroll adjustment**" in [Taking Scroll Into Account](https://www.w3.org/TR/css-anchor-position-1/#scroll):
- query el has a [default anchor element](https://www.w3.org/TR/css-anchor-position-1/#default-anchor-element).
- At least one [anchor()](https://www.w3.org/TR/css-anchor-position-1/#funcdef-anchor) function on query el’s used ...

I'm asking because `anchors-visible` and `anchors-valid` seem to be meaningful only if the anchored element needs scroll adjustment.

If we check these functions, the anchored element with `anchors-visible` and `anchors-valid` will hide e.g. if there is not a default anchor.

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Received on Thursday, 4 April 2024 20:01:54 UTC