[csswg-drafts] [scroll-animations] Computational dependence in start/end (#5185)

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

== [scroll-animations] Computational dependence in start/end ==
The `start` and `end` descriptors (and JS equivalents) accept `<length-percentage>`. This means they accept e.g. `1em` as a value, which depends on the computed value of `font-size`. What is then supposed to happen if e.g. `font-size` is undergoing a transition? Do the `start` and `end` points move dynamically? For consistency with [G-β](https://github.com/w3c/csswg-drafts/issues/5125), then I think yes. Can we then create a cycle if we scroll-link a `font-size` animation? :slightly_smiling_face:

For our own sanity, we should consider imposing a requirement that `start` and `end` must be [computationally independent](https://drafts.css-houdini.org/css-properties-values-api-1/#computationally-independent), though I'm not sure if that loses us some important use-cases. We could add a note in the spec which says it might change in the future.

cc @majido, and also cc @birtles, who I'm sure is thrilled that I'm filing almost the same issue _again_ (#5125).


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/5185 using your GitHub account

Received on Monday, 8 June 2020 10:24:54 UTC