Add overline style and remove keyword, hsl, hsv, hwb and ansi color spaces

[Richienb]

Update ansi-styles package

• Add overline style
• Remove keyword, hsl, hsv, hwb and ansi color spaces

#431

Fixes #360

[Richienb]

Because we no longer downsample ansi is no longer active, level 1 is now effectively the same in function as level 2.

[Qix-]

Just curious, why aren't we downsampling anymore? That seems like a functional regression, given that there are still loads of terminals that only support the older 16 color palette.

[Richienb]

@sindresorhus first suggested to remove it: #300 (comment)

Then you in a seperate conversation, approved removal of ansi: #300 (comment)

[Qix-]

I don't see in there why we need to remove this functionality. I would say we should inline that from color-convert (you're free to copy over the ansi256.ansi16 function from conversions.js directly - not that the license would have prevented you anyway). Just mention it came from color-convert in a comment.

The concern about upscaling (#370) was valid, but downscaling is absolutely necessary to keep compatibility with people who do not have 256 support.

As for the comments about "removing" that - no, those say to remove color-convert and thus the majority of the conversion models, save for hex and rgb. I strongly believe we need to keep ansi256 as well, and be able to downsample to 16-colors if necessary.

cc @sindresorhus

• If chalk is at level 1 and I give it an .rgb(), it should downsample.
• If chalk is at level 2 and I give it an .rgb(), it should downsample.
• If chalk is at level 1 and I give it an .ansi256(), it should downsample.
• If chalk is at level 2 and I give it an .ansi256(), it should pass through.

If we remove downsampling, we're going to irreparably break a LOT of people.

[Richienb]

you're free to copy over the ansi256.ansi16 function from conversions.js directly - not that the license would have prevented you anyway

That function doesn't exist

[Qix-]

Right, you have to merge them - this is untested but should be close enough. Just needs a bit of polish for the Chalk conventions.

function ansi256To16(args) {
	if (args < 8) return 30 + args;
	if (args < 16) return 90 + (args - 8);

	let r, g, b;

	// Handle greyscale
	if (args >= 232) {
		const c = (args - 232) * 10 + 8;
		r = g = b = c / 255;
	} else {
		args -= 16;

		let rem;
		r = Math.floor(args / 36) / 5;
		g = Math.floor((rem = args % 36) / 6) / 5;
		b = (rem % 6) / 5;
	}

        const value = Math.max(r, g, b) * 2;

	if (value === 0) {
		return 30;
	}

	let ansi = 30
		+ ((Math.round(b) << 2)
		| (Math.round(g) << 1)
		| Math.round(r));

	if (value === 2) {
		ansi += 60;
	}

	return ansi;
}

Then just make a bunch of test cases as such:

// Just as an example.
const colorConvert = require('color-convert');
const assert = require('assert').strict.ok;
const {ansi256To16} = require('..');

// Start at 16 since color-convert hasn't been updated to
// correctly return the first 16 colors of ansi-256.
for (let i = 16; i < 256; i++) {
	assert(
		colorConvert.ansi256.ansi16(i) === ansi256To16(i)
	);
}

[Richienb]

Support for ansi has been added back in.

[Qix-]

I don't see anything glaringly wrong with the code; I'll let Sindre have the final look.

[sindresorhus]

I'm confused. I understand preserving the downsampling, but shouldn't we still remove the explicit .ansi() method?

[Richienb]

IMO, there is no impact of leaving the function there so we might as well leave it for people wanting to use the ansi color space. However, I agree that its utility is quite rare but this argument could also be held for ansi256 since it is also a step down from rgb.

[Qix-]

People wanting to use the ansi color space should just use .red(), .blueBright(), etc as it's a 1:1 mapping. People doing programmatic generation of colors for whatever reason are going to be using 256 or truecolor - not 16 - as there is no logical rhyme or reason to the code (I always remember them as "traffic light, dark blue, pink, light blue, white" - completely arbitrary).

I agree with sindre here - no need for .ansi(). Chalk is a utility library, after all - you're always able to write escapes yourself with trivial syntax.

See also: https://en.wikipedia.org/wiki/You_aren%27t_gonna_need_it

[Richienb]

Removed

[Qix-]

LGTM

[sindresorhus]

Nice work, @Richienb 👍

[Qix-]

Yes indeed :) Thanks @Richienb, super appreciated.