1 d3.hsl = function(h, s, l) {

     2   return arguments.length === 1

     3       ? (h instanceof d3_Hsl ? d3_hsl(h.h, h.s, h.l)

     4       : d3_rgb_parse("" + h, d3_rgb_hsl, d3_hsl))

     5       : d3_hsl(+h, +s, +l);

     6 };

     7 

     8 function d3_hsl(h, s, l) {

     9   return new d3_Hsl(h, s, l);

    10 }

    11 

    12 function d3_Hsl(h, s, l) {

    13   this.h = h;

    14   this.s = s;

    15   this.l = l;

    16 }

    17 

    18 d3_Hsl.prototype.brighter = function(k) {

    19   k = Math.pow(0.7, arguments.length ? k : 1);

    20   return d3_hsl(this.h, this.s, this.l / k);

    21 };

    22 

    23 d3_Hsl.prototype.darker = function(k) {

    24   k = Math.pow(0.7, arguments.length ? k : 1);

    25   return d3_hsl(this.h, this.s, k * this.l);

    26 };

    27 

    28 d3_Hsl.prototype.rgb = function() {

    29   return d3_hsl_rgb(this.h, this.s, this.l);

    30 };

    31 

    32 d3_Hsl.prototype.toString = function() {

    33   return this.rgb().toString();

    34 };

    35 

    36 function d3_hsl_rgb(h, s, l) {

    37   var m1,

    38       m2;

    39 

    40   /* Some simple corrections for h, s and l. */

    41   h = h % 360; if (h < 0) h += 360;

    42   s = s < 0 ? 0 : s > 1 ? 1 : s;

    43   l = l < 0 ? 0 : l > 1 ? 1 : l;

    44 

    45   /* From FvD 13.37, CSS Color Module Level 3 */

    46   m2 = l <= .5 ? l * (1 + s) : l + s - l * s;

    47   m1 = 2 * l - m2;

    48 

    49   function v(h) {

    50     if (h > 360) h -= 360;

    51     else if (h < 0) h += 360;

    52     if (h < 60) return m1 + (m2 - m1) * h / 60;

    53     if (h < 180) return m2;

    54     if (h < 240) return m1 + (m2 - m1) * (240 - h) / 60;

    55     return m1;

    56   }

    57 

    58   function vv(h) {

    59     return Math.round(v(h) * 255);

    60   }

    61 

    62   return d3_rgb(vv(h + 120), vv(h), vv(h - 120));

    63 }