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

Adding here what I replied to @keithjgrant via Twitter:

In order to interpolate to/from an `auto` or other keyword value, you 
need to have a way of describing the intermediary state.  For lengths,
 intermediary states can usually be described via a `calc()` function.
  10% of the transition from 50px to 20em is `calc(0.9*50px + 
0.1*20em)`. So the most generic approach to supporting transitions 
with keywords would be to allow the keywords to be used in `calc()`, 
with a real-time substitution of the current computed value that the 
keyword would create.

Sure, there are edge cases where the performance would inevitably be 
horrible (e.g., if you are transitioning to/from `auto` at the same 
time you are also changing things that would cause the current 
computed value of `auto` to change), but that shouldn't be reason to 
prevent its use in more sensible cases.


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Received on Thursday, 20 October 2016 18:05:20 UTC