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

It's not impossible, the behaviour just needs to be written down in order for this to progress into the spec.

@Loirooriol is pointing out that allowing `auto` to be passed to calc enabes the final (used) value to be calculated at layout time, so if that was supported the `auto` would be recalculated at each discreet transition step (thing requestAnimationFrame I guess?)

In the absence of such a proposal (which is elegant and general, but I don't think anyone is clamouring or has worked out the edge cases), and also because the 'virtual layout' calculations could potentially be costly, would it be possible from a spec point of view to defer the implementation details to the browser:

 - browsers iniitally calculate a 'virtual' used value for `auto` at the start of the transition given current conditions
 - browsers _must_ recalculate `auto` at the end of the transition to ensure that the used value has not changed since the start of the transition
 - browser _may_ recalculate a used value for `auto` at each step of the transition for a smoother transition in the presence of other changes

Is there precedence for this style of specification?

Should we write up the various approaches in separate issues?  @Loirooriol a stub of each of the competing possibilities that are in your head would be very helpful!

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Received on Tuesday, 1 March 2022 15:17:06 UTC