color-hash/lib/colors.ts

Generate color based on the given string (using HSL color space and SHA256).

/**
 * Convert RGB Array to HEX
 *
 * @param {Array} RGBArray - [R, G, B]
 * @returns {String} 6 digits hex starting with #
 */
 const RGB2HEX = function(RGBArray: number[]) {
    var hex = '#';
    RGBArray.forEach(function(value) {
        if (value < 16) {
            hex += 0;
        }
        hex += value.toString(16);
    });
    return hex;
};

/**
 * Convert HSL to RGB
 *
 * @see {@link http://zh.wikipedia.org/wiki/HSL和HSV色彩空间} for further information.
 * @param {Number} H Hue ∈ [0, 360)
 * @param {Number} S Saturation ∈ [0, 1]
 * @param {Number} L Lightness ∈ [0, 1]
 * @returns {Array} R, G, B ∈ [0, 255]
 */
const HSL2RGB = function(H: number, S: number, L: number) {
    H /= 360;

    var q = L < 0.5 ? L * (1 + S) : L + S - L * S;
    var p = 2 * L - q;

    return [H + 1/3, H, H - 1/3].map(function(color) {
        if(color < 0) {
            color++;
        }
        if(color > 1) {
            color--;
        }
        if(color < 1/6) {
            color = p + (q - p) * 6 * color;
        } else if(color < 0.5) {
            color = q;
        } else if(color < 2/3) {
            color = p + (q - p) * 6 * (2/3 - color);
        } else {
            color = p;
        }
        return Math.round(color * 255);
    });
};

export {RGB2HEX, HSL2RGB};