js-utl/src/modules/color.js

A collection of JS utility functions to be used across several applications or libraries.

/*
 * Copyright (c) 2022 Anton Bagdatyev (Tonix)
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

import { hashString } from "./hash";

/**
 * Color-related utility functions.
 */

/**
 * Gets a color's luminance.
 *
 * @param {number} color Color int value (RGB).
 * @return {number} An int greater than 160 if the color is considered dark and less than or
 *                  equal to 160 if the color is considered light.
 */
export function getLuminance(color) {
  const c = parseInt(color, 16);
  const r = (c & 0xff0000) >> 16;
  const g = (c & 0x00ff00) >> 8;
  const b = c & 0x0000ff;
  return 0.299 * r + 0.587 * g + 0.114 * b;
}

/**
 * Converts an integer to an RGB hex (hexadecimal) string.
 *
 * @param {number} i An integer.
 * @return {string} An RGB hex string (uppercase).
 */
export function intToRGBHexString(i) {
  const c = (i & 0x00ffffff).toString(16).toUpperCase();
  return "00000".substring(0, 6 - c.length) + c;
}

/**
 * Converts a string to an RGB hex (hexadecimal) string representing a color.
 *
 * @param {string} str The string.
 * @return {string} The color as an RGB hex string (uppercase).
 */
export const colorFromString = str => {
  const hash = hashString(str);
  return intToRGBHexString(hash);
};