niram/dist/helpers/rgbToHsl.js

A javascript library to convert between various css colour formats.

import { normaliseDegree } from './normalisers.js';
export function rgbToHsl(red, green, blue, alphaFraction = 1) {
    const red_ = red / 255;
    const green_ = green / 255;
    const blue_ = blue / 255;
    const C_max = Math.max(red_, green_, blue_);
    const C_min = Math.min(red_, green_, blue_);
    const C_diff = C_max - C_min;
    const levelFraction = (C_max + C_min) / 2;
    const satFraction = C_diff / (1 - Math.abs(2 * levelFraction - 1));
    const hueDegree = normaliseDegree(getHueDegreeFromRgbFraction(red_, green_, blue_, C_max, C_diff));
    return {
        hueDegree,
        satPercent: satFraction * 100,
        levelPercent: levelFraction * 100,
        alphaFraction,
    };
}
function getHueDegreeFromRgbFraction(red_, green_, blue_, C_max, C_diff) {
    if (C_diff == 0) {
        return 0;
    }
    else if (C_max == red_) {
        return 60 * (((green_ - blue_) / C_diff) % 6);
    }
    else if (C_max == green_) {
        return 60 * ((blue_ - red_) / C_diff + 2);
    }
    else if (C_max == blue_) {
        return 60 * ((red_ - green_) / C_diff + 4);
    }
    return 0;
}