[csswg-drafts] [scroll-animations-1] Syntax of animation-range is ambiguous (#8557)

ydaniv has just created a new issue for https://github.com/w3c/csswg-drafts:

== [scroll-animations-1] Syntax of animation-range is ambiguous ==
Since we resolved in #7575 to allow `<length-percentage>` to be used as offsets in `animation-range`, it's now possible to have a range of:
```css
.source {
  animation-timeline: view(self);
  animation-range: entry 0 contain 20%;
}
```
Which can now mean 2 things:

1. The animation's progress is at 100% when `.source` is at 20% of its `contain` range.
2. The animation's progress is at 100% when `.source` is at `contain 0%` + 20% of its parent's size (according to timeline's axis).

In order to be able to distinguish between the 2 cases we have the following **options**:

1. Make ranges functions, so that `contain 20%` becomes `contain(20%)`
2. Disallow `<percentage>` so that it only means 1. from the options above. But that seems suboptimal.
3. Adopt suggestions in #8054 to use the `offset()` and `range()` notations so that we get `offset(contain 20%)`

Anyhow, since we already have other ambiguity issues raised in #8054, I guess we could solve both by  adopting either option 1 or option 3.

cc @flackr @fantasai @bramus 

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/8557 using your GitHub account


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Received on Friday, 10 March 2023 20:44:29 UTC