color.js

function colorLuminance(hex, lum) {
  // validate hex string
  hex = String(hex).replace(/[^0-9a-f]/gi, '');
  if (hex.length < 6) {
    hex = hex[0] + hex[0] + hex[1] + hex[1] + hex[2] + hex[2];
  }
  lum = lum || 0;

  // convert to decimal and change luminosity
  var rgb = '#', c, i;
  for (i = 0; i < 3; i++) {
    c = parseInt(hex.substr(i * 2, 2), 16);
    c = Math.round(Math.min(Math.max(0, c + (c * lum)), 255)).toString(16);
    rgb += (`00${c}`).substr(c.length);
  }

  return rgb;
}

export function hexToRgb(hex) {
  let result;
  if (hex.match(/^#.{3}$/)) {
    result = /^#?([a-f\d])([a-f\d])([a-f\d])$/i.exec(hex);
    result[1] += result[1];
    result[2] += result[2];
    result[3] += result[3];
  } else {
    result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  }
  return result ? {
    r: parseInt(result[1], 16),
    g: parseInt(result[2], 16),
    b: parseInt(result[3], 16)
  } : null;
}

export function transparentize(color, amount) {
  const c = hexToRgb(color);
  return `rgba(${c.r}, ${c.g}, ${c.b}, ${Math.round((1 - amount) * 1000) / 1000})`;
}

export function darkenColor(color, percent) {
  return colorLuminance(color, -percent);
}

export function ligthenColor(color) {
  return color;
}

export function convertColor(color) {
  var colors = {
    'aliceblue':'#f0f8ff','antiquewhite':'#faebd7','aqua':'#00ffff','aquamarine':'#7fffd4','azure':'#f0ffff',
    'beige':'#f5f5dc','bisque':'#ffe4c4','black':'#000000','blanchedalmond':'#ffebcd','blue':'#0000ff','blueviolet':'#8a2be2','brown':'#a52a2a','burlywood':'#deb887',
    'cadetblue':'#5f9ea0','chartreuse':'#7fff00','chocolate':'#d2691e','coral':'#ff7f50','cornflowerblue':'#6495ed','cornsilk':'#fff8dc','crimson':'#dc143c','cyan':'#00ffff',
    'darkblue':'#00008b','darkcyan':'#008b8b','darkgoldenrod':'#b8860b','darkgray':'#a9a9a9','darkgreen':'#006400','darkkhaki':'#bdb76b','darkmagenta':'#8b008b','darkolivegreen':'#556b2f',
    'darkorange':'#ff8c00','darkorchid':'#9932cc','darkred':'#8b0000','darksalmon':'#e9967a','darkseagreen':'#8fbc8f','darkslateblue':'#483d8b','darkslategray':'#2f4f4f','darkturquoise':'#00ced1',
    'darkviolet':'#9400d3','deeppink':'#ff1493','deepskyblue':'#00bfff','dimgray':'#696969','dodgerblue':'#1e90ff',
    'firebrick':'#b22222','floralwhite':'#fffaf0','forestgreen':'#228b22','fuchsia':'#ff00ff',
    'gainsboro':'#dcdcdc','ghostwhite':'#f8f8ff','gold':'#ffd700','goldenrod':'#daa520','gray':'#808080','green':'#008000','greenyellow':'#adff2f',
    'honeydew':'#f0fff0','hotpink':'#ff69b4',
    'indianred ':'#cd5c5c','indigo':'#4b0082','ivory':'#fffff0','khaki':'#f0e68c',
    'lavender':'#e6e6fa','lavenderblush':'#fff0f5','lawngreen':'#7cfc00','lemonchiffon':'#fffacd','lightblue':'#add8e6','lightcoral':'#f08080','lightcyan':'#e0ffff','lightgoldenrodyellow':'#fafad2',
    'lightgrey':'#d3d3d3','lightgreen':'#90ee90','lightpink':'#ffb6c1','lightsalmon':'#ffa07a','lightseagreen':'#20b2aa','lightskyblue':'#87cefa','lightslategray':'#778899','lightsteelblue':'#b0c4de',
    'lightyellow':'#ffffe0','lime':'#00ff00','limegreen':'#32cd32','linen':'#faf0e6',
    'magenta':'#ff00ff','maroon':'#800000','mediumaquamarine':'#66cdaa','mediumblue':'#0000cd','mediumorchid':'#ba55d3','mediumpurple':'#9370d8','mediumseagreen':'#3cb371','mediumslateblue':'#7b68ee',
    'mediumspringgreen':'#00fa9a','mediumturquoise':'#48d1cc','mediumvioletred':'#c71585','midnightblue':'#191970','mintcream':'#f5fffa','mistyrose':'#ffe4e1','moccasin':'#ffe4b5',
    'navajowhite':'#ffdead','navy':'#000080',
    'oldlace':'#fdf5e6','olive':'#808000','olivedrab':'#6b8e23','orange':'#ffa500','orangered':'#ff4500','orchid':'#da70d6',
    'palegoldenrod':'#eee8aa','palegreen':'#98fb98','paleturquoise':'#afeeee','palevioletred':'#d87093','papayawhip':'#ffefd5','peachpuff':'#ffdab9','peru':'#cd853f','pink':'#ffc0cb','plum':'#dda0dd','powderblue':'#b0e0e6','purple':'#800080',
    'red':'#ff0000','rosybrown':'#bc8f8f','royalblue':'#4169e1',
    'saddlebrown':'#8b4513','salmon':'#fa8072','sandybrown':'#f4a460','seagreen':'#2e8b57','seashell':'#fff5ee','sienna':'#a0522d','silver':'#c0c0c0','skyblue':'#87ceeb','slateblue':'#6a5acd','slategray':'#708090','snow':'#fffafa','springgreen':'#00ff7f','steelblue':'#4682b4',
    'tan':'#d2b48c','teal':'#008080','thistle':'#d8bfd8','tomato':'#ff6347','turquoise':'#40e0d0',
    'violet':'#ee82ee',
    'wheat':'#f5deb3','white':'#ffffff','whitesmoke':'#f5f5f5',
    'yellow':'#ffff00','yellowgreen':'#9acd32'
  };

  if (typeof color === 'string' && typeof colors[color.toLowerCase()] != 'undefined') {
    return colors[color.toLowerCase()];
  }
  return color;
}

export function isDarkColor(color) {
  const c = convertColor(color).substring(1);      // strip #
  const rgb = parseInt(c, 16);   // convert rrggbb to decimal
  const r = (rgb >> 16) & 0xff;  // extract red
  const g = (rgb >> 8) & 0xff;  // extract green
  const b = (rgb >> 0) & 0xff;  // extract blue

  const luma = 0.2126 * r + 0.7152 * g + 0.0722 * b; // per ITU-R BT.709

  return luma < 40;
}