@cquiroz/aladin-lite/lib/js/Color.js

AladinLite module

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

// Copyright 2013 - UDS/CNRS
// The Aladin Lite program is distributed under the terms
// of the GNU General Public License version 3.
//
// This file is part of Aladin Lite.
//
//    Aladin Lite is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, version 3 of the License.
//
//    Aladin Lite 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 General Public License for more details.
//
//    The GNU General Public License is available in COPYING file
//    along with Aladin Lite.
//

/******************************************************************************
 * Aladin Lite project
 *
 * File Color
 *
 * Author: Thomas Boch[CDS]
 *
 *****************************************************************************/
export default class Color {
  static getNextColor() {
    var c = Color.colors[Color.curIdx % Color.colors.length];
    Color.curIdx++;
    return c;
  }
  /** return most suited (ie readable) color for a label, given a background color
   * bkgdColor: color, given as a 'rgb(<r value>, <g value>, <v value>)' . This is returned by $(<element>).css('background-color')
   *
   * example call: Color.getLabelColorForBackground('rgb(3, 123, 42)')
   * adapted from http://stackoverflow.com/questions/1855884/determine-font-color-based-on-background-color
   */


  static getLabelColorForBackground(rgbBkgdColor) {
    var lightLabel = '#eee';
    var darkLabel = '#111';
    var rgb = rgbBkgdColor.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);

    if (rgb == null) {
      // we return the dark label color if we can't parse the color
      return darkLabel;
    }

    var r = parseInt(rgb[1]);
    var g = parseInt(rgb[2]);
    var b = parseInt(rgb[3]); // Counting the perceptive luminance - human eye favors green color...

    var a = 1 - (0.299 * r + 0.587 * g + 0.114 * b) / 255;

    if (a < 0.5) {
      return darkLabel; // bright color --> dark font
    } else {
      return lightLabel; // dark color --> light font
    }
  }

}

_defineProperty(Color, "curIdx", 0);

_defineProperty(Color, "colors", ['#ff0000', '#0000ff', '#99cc00', '#ffff00', '#000066', '#00ffff', '#9900cc', '#0099cc', '#cc9900', '#cc0099', '#00cc99', '#663333', '#ffcc9a', '#ff9acc', '#ccff33', '#660000', '#ffcc33', '#ff00ff', '#00ff00', '#ffffff']);