Re: [csswg-drafts] [css-transitions] Transition to height (or width) "auto" (#626)

> the resolved current value should suddenly change from 100px to 125px

Ok, this initially sounded confusing, as it's not immediately apparent to me why this should be desired behaviour, but I guess you are saying that because there is currently a jump if content is added to a container, therefore there should also be a jump if content is added during the transition.
Note: this isn't the current behaviour with explicit transitions; https://software.hixie.ch/utilities/js/live-dom-viewer/  but I accept the behaviour needs to be defined for when the value which was initially computed for `auto` changes during transition.  You've likely been arguing that this is the crux of the point all along?

There are two solutions I can see:
 A) after finishing the transition, recalculate what `auto` should be; the jump may happen then (if extra content has been added and the height computed for `auto` is now larger)
 B) if contents change during transition then recalculate `auto`, and replace the value fed into that ` calc(a*(1-t) + b*t)` function (note I still don't think that you need to add spec-level support for `auto` within `calc`) .. the correct jump should happen then.

I imagine this is not the type of thing that you'd want left undefined?
If so have I think B) is the desired behaviour (I think most here wouldn't care whether it's A or B).
B) may well be easier if `auto` was `calc`able, but from reading about the problematic edge cases that you mentioned, I'm not fully convinced whether support for something like `height: calc(auto + 5px); align-self: stretch` would ever be desirable; if you can't easily explain it then should it be supported?

Have I convinced you that B) is doable without having to support `auto` in `calc` and that it's desirable to push that through well before any more general case support for `auto` within `calc`?


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Received on Monday, 28 February 2022 15:17:42 UTC