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var DrawTools = new function () {
  /**
   * Get cross-browser animation callback.
   */
  this.requestAnimFrame = window.requestAnimationFrame
    || window.webkitRequestAnimationFrame
    || window.mozRequestAnimationFrame
    || window.oRequestAnimationFrame
    || window.msRequestAnimationFrame
    || function (callback) {
    return setTimeout(callback, 1E3 / 60);
  };

  /**
   * Covert color encoding.
   */
  this.hexToRGB = function (a) {
    var b, c, e;
    b = /^#?([a-f0-9]{2})([a-f0-9]{2})([a-f0-9]{2})$/i.exec(a).slice(1);
    e = [];
    for (a = c = 0; 2 >= c; a = ++c) e.push(parseInt(b[a], 16));
    return e
  };

  /**
   * Generate random from interval.
   */
  this.randrange = function (from, to) {
    return from + Math.random() * (to - from);
  };

  /**
   * Return brighten version of color.
   */
  this.brightenRGB = function (a, b, c, e) {
    return [Math.floor(Math.min(255, a + 255 * e)), Math.floor(Math.min(255, b + 255 * e)), Math.floor(Math.min(255, c + 255 * e))];
  };

  /**
   * Converts an RGB color value to HSL. Conversion formula
   * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
   * Assumes r, g, and b are contained in the set [0, 255] and
   * returns h, s, and l in the set [0, 1].
   *
   * @param   Number  r       The red color value
   * @param   Number  g       The green color value
   * @param   Number  b       The blue color value
   * @return  Array           The HSL representation
   */
  this.rgbToHsl = function (r, g, b) {
    r /= 255, g /= 255, b /= 255;

    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, l = (max + min) / 2;

    if (max == min) {
      h = s = 0; // achromatic
    } else {
      var d = max - min;
      s = l > 0.5 ? d / (2 - max - min) : d / (max + min);

      switch (max) {
        case r:
          h = (g - b) / d + (g < b ? 6 : 0);
          break;
        case g:
          h = (b - r) / d + 2;
          break;
        case b:
          h = (r - g) / d + 4;
          break;
      }

      h /= 6;
    }

    return [ h, s, l ];
  }

  /**
   * Converts an HSL color value to RGB. Conversion formula
   * adapted from http://en.wikipedia.org/wiki/HSL_color_space.
   * Assumes h, s, and l are contained in the set [0, 1] and
   * returns r, g, and b in the set [0, 255].
   *
   * @param   Number  h       The hue
   * @param   Number  s       The saturation
   * @param   Number  l       The lightness
   * @return  Array           The RGB representation
   */
  this.hslToRgb = function (h, s, l) {
    var r, g, b;

    if (s == 0) {
      r = g = b = l; // achromatic
    } else {
      function hue2rgb(p, q, t) {
        if (t < 0) t += 1;
        if (t > 1) t -= 1;
        if (t < 1 / 6) return p + (q - p) * 6 * t;
        if (t < 1 / 2) return q;
        if (t < 2 / 3) return p + (q - p) * (2 / 3 - t) * 6;
        return p;
      }

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

      r = hue2rgb(p, q, h + 1 / 3);
      g = hue2rgb(p, q, h);
      b = hue2rgb(p, q, h - 1 / 3);
    }

    return [ r * 255, g * 255, b * 255 ];
  }

  /**
   * Converts an RGB color value to HSV. Conversion formula
   * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
   * Assumes r, g, and b are contained in the set [0, 255] and
   * returns h, s, and v in the set [0, 1].
   *
   * @param   Number  r       The red color value
   * @param   Number  g       The green color value
   * @param   Number  b       The blue color value
   * @return  Array           The HSV representation
   */
  this.rgbToHsv = function (r, g, b) {
    r /= 255, g /= 255, b /= 255;

    var max = Math.max(r, g, b), min = Math.min(r, g, b);
    var h, s, v = max;

    var d = max - min;
    s = max == 0 ? 0 : d / max;

    if (max == min) {
      h = 0; // achromatic
    } else {
      switch (max) {
        case r:
          h = (g - b) / d + (g < b ? 6 : 0);
          break;
        case g:
          h = (b - r) / d + 2;
          break;
        case b:
          h = (r - g) / d + 4;
          break;
      }

      h /= 6;
    }

    return [ h, s, v ];
  }

  /**
   * Converts an HSV color value to RGB. Conversion formula
   * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
   * Assumes h, s, and v are contained in the set [0, 1] and
   * returns r, g, and b in the set [0, 255].
   *
   * @param   Number  h       The hue
   * @param   Number  s       The saturation
   * @param   Number  v       The value
   * @return  Array           The RGB representation
   */
  this.hsvToRgb = function (h, s, v) {
    var r, g, b;

    var i = Math.floor(h * 6);
    var f = h * 6 - i;
    var p = v * (1 - s);
    var q = v * (1 - f * s);
    var t = v * (1 - (1 - f) * s);

    switch (i % 6) {
      case 0:
        r = v, g = t, b = p;
        break;
      case 1:
        r = q, g = v, b = p;
        break;
      case 2:
        r = p, g = v, b = t;
        break;
      case 3:
        r = p, g = q, b = v;
        break;
      case 4:
        r = t, g = p, b = v;
        break;
      case 5:
        r = v, g = p, b = q;
        break;
    }

    return [ r * 255, g * 255, b * 255 ];
  }
}();