iobroker.shelly/lib/colorconv.js

Integrate your Shelly devices into ioBroker via MQTT or CoAP

/**
 * Converts an RGB color value to HSV. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
 * Assumes r, g, and b are contained in the set [0, 255] and
 * returns h, s, and v in the set [0, 1].
 *
 * @param r red color value
 * @param g green color value
 * @param b blue color value
 * @returns Array           The HSV representation
 */
function rgbToHsv(r, g, b) {
    r /= 255;
    g /= 255;
    b /= 255;

    const max = Math.max(r, g, b);
    const min = Math.min(r, g, b);
    let h;
    let s = max;
    const v = max;

    const d = max - min;
    s = !max ? 0 : d / max;

    if (max === min) {
        h = 0; // achromatic
    } else {
        switch (max) {
            case r:
                h = (g - b) / d + (g < b ? 6 : 0);
                break;
            case g:
                h = (b - r) / d + 2;
                break;
            case b:
                h = (r - g) / d + 4;
                break;
        }

        h /= 6;
    }

    // return [h, s, v];
    // return [h * 360, s * 100, v * 100];
    return [Math.round(h * 360), Math.round(s * 100), Math.round(v * 100)];
}

/**
 * Converts an HSV color value to RGB. Conversion formula
 * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
 * Assumes h, s, and v are contained in the set [0, 1] and
 * returns r, g, and b in the set [0, 255].
 *
 * @param h
 * @param s
 * @param v
 * @returns  Array           The RGB representation
 */
function hsvToRgb(h, s, v) {
    h = h / 360;
    s = s / 100;
    v = v / 100;

    let r, g, b;
    const i = Math.floor(h * 6);
    const f = h * 6 - i;
    const p = v * (1 - s);
    const q = v * (1 - f * s);
    const t = v * (1 - (1 - f) * s);

    switch (i % 6) {
        case 0:
            ((r = v), (g = t), (b = p));
            break;
        case 1:
            ((r = q), (g = v), (b = p));
            break;
        case 2:
            ((r = p), (g = v), (b = t));
            break;
        case 3:
            ((r = p), (g = q), (b = v));
            break;
        case 4:
            ((r = t), (g = p), (b = v));
            break;
        case 5:
            ((r = v), (g = p), (b = q));
            break;
    }

    // return [r * 255, g * 255, b * 255];
    return [Math.round(r * 255), Math.round(g * 255), Math.round(b * 255)];
}

module.exports = {
    rgbToHsv,
    hsvToRgb,
};