60 lines
1.3 KiB
JavaScript
60 lines
1.3 KiB
JavaScript
import normalizeHue from '../util/normalizeHue.js';
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// Based on: https://en.wikipedia.org/wiki/HSL_and_HSV#Converting_to_RGB
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export default function convertHsiToRgb({ h, s, i, alpha }) {
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h = normalizeHue(h);
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let f = Math.abs(((h / 60) % 2) - 1);
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let res;
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switch (Math.floor(h / 60)) {
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case 0:
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res = {
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r: i * (1 + s * (3 / (2 - f) - 1)),
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g: i * (1 + s * ((3 * (1 - f)) / (2 - f) - 1)),
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b: i * (1 - s)
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};
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break;
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case 1:
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res = {
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r: i * (1 + s * ((3 * (1 - f)) / (2 - f) - 1)),
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g: i * (1 + s * (3 / (2 - f) - 1)),
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b: i * (1 - s)
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};
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break;
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case 2:
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res = {
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r: i * (1 - s),
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g: i * (1 + s * (3 / (2 - f) - 1)),
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b: i * (1 + s * ((3 * (1 - f)) / (2 - f) - 1))
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};
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break;
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case 3:
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res = {
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r: i * (1 - s),
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g: i * (1 + s * ((3 * (1 - f)) / (2 - f) - 1)),
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b: i * (1 + s * (3 / (2 - f) - 1))
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};
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break;
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case 4:
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res = {
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r: i * (1 + s * ((3 * (1 - f)) / (2 - f) - 1)),
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g: i * (1 - s),
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b: i * (1 + s * (3 / (2 - f) - 1))
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};
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break;
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case 5:
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res = {
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r: i * (1 + s * (3 / (2 - f) - 1)),
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g: i * (1 - s),
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b: i * (1 + s * ((3 * (1 - f)) / (2 - f) - 1))
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};
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break;
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default:
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res = { r: i * (1 - s), g: i * (1 - s), b: i * (1 - s) };
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}
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res.mode = 'rgb';
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if (alpha !== undefined) res.alpha = alpha;
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return res;
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}
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