[csswg-drafts] [css-color-5] How exactly does the hue adjuster in color-adjust() work? (#6180)

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

== [css-color-5] How exactly does the hue adjuster in color-adjust() work? ==
In ['color-adjust()`](https://drafts.csswg.org/css-color-5/#coloradjust), the spaces with hue have a hue-adjuster that looks like (grammar folded together):

`hue [shorter | longer | increasing | decreasing | specified ]? <percentage>?`

This seems odd in at least two ways.

1. Adjusting a hue by percentage seems like it's a domain error. Hue is a circular range; it doesn't have a *meaningful* zero to adjust toward or away from. In HSL, `blue hue 50%` changes the hue from 240deg to 120deg, but `green hue 50%` adjusts it from 120deg to 60deg; I don't think there's a meaningful sense in which green is "half" of blue, or yellow is "half" of green.

2. The shorter/longer/etc keyword seems to not do anything? That keyword is for choosing between several behaviors of interpolating between two hues; that doesn't appear to be relevant here. The spec just refers to the definition of the keywords, but doesn't explain what they actually do, or have an example of it.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/6180 using your GitHub account


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Received on Tuesday, 6 April 2021 14:38:45 UTC