Intent to Prototype: mix-blend-mode: plus-lighter

[Vladimir Levin]

Contact emails

vmp...@chromium.org, khusha...@chromium.org, jakear...@chromium.org

Explainer

https://jakearchibald.com/2021/dom-cross-fade/

Specification

https://drafts.fxtf.org/compositing-2/#porterduffcompositingoperators_plus_lighter

Summary

This proposal adds a plus-lighter value to the mix-blend-mode property. Plus-lighter adds the source and destination colors multiplied by their respective alphas. This operation is useful when cross fading between two elements that may contain common pixels. In that case, plus-lighter ensures that the common pixels do not change in appearance as opacity changes from 0 to 1 on one element and from 1 to 0 on the other.

Blink component

Blink>CSS

Motivation

mix-blend-mode: plus-lighter allows two elements to cross fade by changing their opacities from 0 to 1 on one element and 1 to 0 on the other element, which keeping common pixels unmodified.

Initial public proposal

Search tags

plus-lighter

TAG review

N/A -- This is a small addition to an existing CSS property.

TAG review status

Not applicable

Risks

Interoperability and Compatibility

Gecko: No signal

WebKit: Shipped/Shipping (https://github.com/w3c/fxtf-drafts/issues/445#issuecomment-995022125)

Web developers: No signals

Other signals:

Ergonomics

This adds a new value to an existing CSS property. The ergonomics risk is minimal.

Activation

This adds a new value to an existing CSS property. The activation risk is minimal. This property is straight-forward to use.

Security

There are no security risks associated with this property.

Debuggability

This relies on existing debuggability of CSS mix-blend-mode.

Is this feature fully tested by web-platform-tests?

Yes

Requires code in //chrome?

False

Tracking bug

https://bugs.chromium.org/p/chromium/issues/detail?id=1275782

Estimated milestones

No milestones specified

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5677338286096384

This intent message was generated by Chrome Platform Status.

[Manuel Rego Casasnovas]

On 16/12/2021 21:44, Vladimir Levin wrote:
> Gecko: No signal

Have we asked for signals? https://bit.ly/blink-signals

> WebKit: Shipped/Shipping
> (https://github.com/w3c/fxtf-drafts/issues/445#issuecomment-995022125
> <https://github.com/w3c/fxtf-drafts/issues/445#issuecomment-995022125>)

The issue resolution also mentions plus-darker, but that's not mentioned
on this intent. Do we support it already or have plans around it?

Thanks,
Rego

[Vladimir Levin]

Hi Rego,

Thank you for your feedback.

I just filed https://github.com/mozilla/standards-positions/issues/607 as a request for a position from Mozilla.

We don't have any immediate plans to implement or support plus-darker, but I will file some bugs to explore how viable it is for us to support this in the future.

Thanks,

Vlad

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