Edit File: convertRgbToCubehelix.js
/* Convert a RGB color to the Cubehelix HSL color space. This computation is not present in Green's paper: https://arxiv.org/pdf/1108.5083.pdf ...but can be derived from the inverse, HSL to RGB conversion. It matches the math in Mike Bostock's D3 implementation: https://github.com/d3/d3-color/blob/master/src/cubehelix.js */ import { radToDeg, M } from './constants.js'; let DE = M[3] * M[4]; let BE = M[1] * M[4]; let BCAD = M[1] * M[2] - M[0] * M[3]; const convertRgbToCubehelix = ({ r, g, b, alpha }) => { let l = (BCAD * b + r * DE - g * BE) / (BCAD + DE - BE); let x = b - l; let y = (M[4] * (g - l) - M[2] * x) / M[3]; let res = { mode: 'cubehelix', l: l, s: l === 0 || l === 1 ? undefined : Math.sqrt(x * x + y * y) / (M[4] * l * (1 - l)) }; if (res.s) res.h = Math.atan2(y, x) * radToDeg - 120; if (alpha !== undefined) res.alpha = alpha; return res; }; export default convertRgbToCubehelix;
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