sonarqube/server/sonar-web/src/main/js/helpers/colors.ts

/*
 * SonarQube
 * Copyright (C) 2009-2018 SonarSource SA
 * mailto:info AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

/* eslint-disable no-bitwise, no-mixed-operators */
export function stringToColor(str: string) {
  let hash = 0;
  for (let i = 0; i < str.length; i++) {
    hash = str.charCodeAt(i) + ((hash << 5) - hash);
  }
  let color = '#';
  for (let i = 0; i < 3; i++) {
    const value = (hash >> (i * 8)) & 0xff;
    color += ('00' + value.toString(16)).substr(-2);
  }
  return color;
}

export function isDarkColor(color: string) {
  color = color.substr(1);
  if (color.length === 3) {
    // shortcut notation: #f90
    color = color[0] + color[0] + color[1] + color[1] + color[2] + color[2];
  }
  const rgb = parseInt(color.substr(1), 16);
  const r = (rgb >> 16) & 0xff;
  const g = (rgb >> 8) & 0xff;
  const b = (rgb >> 0) & 0xff;
  const luma = 0.2126 * r + 0.7152 * g + 0.0722 * b;
  return luma < 140;
}

export function getTextColor(background: string, dark = '#222', light = '#fff') {
  return isDarkColor(background) ? light : dark;
}