[csswg-drafts] [css-transforms-1] Should will-change: transform be treated as transform for background-attachment:fixed? (#6951)

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

== [css-transforms-1] Should will-change: transform be treated as transform for background-attachment:fixed? ==
The [current spec](https://www.w3.org/TR/css-transforms-1/#transform-rendering) says:

> Fixed backgrounds on the root element are affected by any transform specified for that element. For all other elements that are effected by a transform (i.e. have a transform applied to them, or to any of their ancestor elements), a value of fixed for the background-attachment property is treated as if it had a value of scroll. The computed value of background-attachment is not affected.

It doesn't mention will-change:transform. However, if we don't treat will-change:transform as transform, future change of transform from initial to non-identity will cause jump of the background.

Current browser behaviors about treating will-change:transform as transform for background-attachment-fixed:
- Firefox: Yes
- Chrome: No, but it will be Yes after https://chromium-review.googlesource.com/c/chromium/src/+/3385337 is landed.
- Safari: No


Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6951 using your GitHub account


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Received on Friday, 14 January 2022 05:18:36 UTC