2020-10-07 01:57:37 +02:00
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---
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title: "Request for Comments: HWB Functions"
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author: Natalie Weizenbaum
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date: 2020-10-06 16:00 PST
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---
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The CSS working group has been up to all sorts of exciting stuff recently in the
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[Color Level 4] spec, and the Sass team is starting to think about how to
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integrate those cool new features into Sass's color model. We need more time to
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hammer out exactly the right designs for complex features like the Lab color
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space, but that doesn't mean we can't add a few new color goodies.
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[Color Level 4]: https://www.w3.org/TR/css-color-4/
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Today we're announcing a proposal for one such feature: built-in Sass functions
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for [HWB] colors! Once this proposal (drafted by Sass core team member [Miriam
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Suzanne]) is accepted and implemented, you'll be able to write colors in HWB
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syntax and adjust their whiteness and blackness the same way you can adjust a
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color's saturation and lightness today.
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[HWB]: https://www.w3.org/TR/css-color-4/#the-hwb-notation
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[Miriam Suzanne]: https://www.miriamsuzanne.com/
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## The Functions
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Here are the new and improved functions this proposal adds:
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### `color.hwb()`
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The `color.hwb()` function defines a color using its hue, whiteness, and
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blackness. Like the existing `rgb()` and `hsl()` functions, It can either use
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the space-separated syntax defined in [the spec][HWB] (`hwb(270 20% 40%)`) or
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the more Sass-y comma-separated syntax (`hwb(270, 20%, 40%)`). Because HWB
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colors use the same sRGB colorspace as all other Sass color values, colors
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created this way are fully compatible with all existing Sass color functions and
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will be emitted as their RGB equivalents for maximum browser compatibility.
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Note that *unlike* `rgb()` and `hsl()`, the proposal doesn't add this function
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to the global scope yet. This is because Sass has a policy of never adding
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support for new CSS syntax before at least one browser implements it. Specs have
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a tendency to change until they're locked in by browsers, and if Sass ends up
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supporting something different than the browsers themselves that's bad news!
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### `color.whiteness()` and `color.blackness()`
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These functions work like the `color.saturation()` and `color.lightness()`
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functions do for HSL colors. They even work for colors that weren't created with
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`color.hwb()`, so you can use them to check how pale or dark any color is.
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Because HWB colors have the same notion of "hue" as HSL colors, the existing
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`color.hue()` function already works perfectly!
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### `color.scale()`, `color.adjust()`, and `color.change()`
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All three color modification functions now support `$whiteness` and `$blackness`
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arguments. If you want a color (again no matter how it was created) to be 20%
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whiter, just pass it to `color.scale($color, $whiteness: 20%)` and there you go!
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## Let us know what you think!
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If you’re interested in learning more about this proposal, [read it in full] on
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GitHub. It’s open for comments and revisions for the next month, so if you’d
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like to see something change please [file an issue] and we can discuss it!
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2021-07-24 01:28:41 +02:00
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[read it in full]: https://github.com/sass/sass/tree/main/proposal/color-4-hwb.md
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2020-10-07 01:57:37 +02:00
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[file an issue]: https://github.com/sass/sass/issues/new
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