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

@danegraphics  The issue is that transitions interpolate computed values, and in `height`/ `width` a specified value of `auto` computes to `auto` which is not a `<length-percentage>`, and we know how to interpolate `<length-percentage>`s but not `auto`. So either we define how to interpolate `auto` with a `<length-percentage>`, or somehow add another way to transition that interpolates used values.

The computation cost will probably be there anyways no matter what we do, since changing `height` already implies layout at every step, yes. For a performant approach, transforms should be used instead, as explained in https://github.com/w3c/csswg-drafts/issues/626#issuecomment-841935150 and https://github.com/w3c/csswg-drafts/issues/626#issuecomment-842707084

In order to interpolate `auto`, the specs would need to define how a mix of `auto` and `<length-percentage>` behaves during intrinsic sizing and extrinsic sizing, clarify if things that check if the computed value is `auto` should check for exactly `auto` or also `auto` mixed with a `<length-percentage>`, etc.

@eoghanmurray Well, I guess it depends on what exactly you count. If you have cyclic percentages, the elements is laid out as `auto` during intrinsic sizing, and then as a definite percentage during extrinsic sizing. With a mix of `auto` and `<length-percentage>`, the details of what needs to be done will depend on how exactly it's defined.

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Received on Wednesday, 2 March 2022 13:08:26 UTC