1 function d3_svg_area(projection) {

     2   var x0 = d3_svg_lineX,

     3       x1 = d3_svg_lineX,

     4       y0 = 0,

     5       y1 = d3_svg_lineY,

     6       interpolate,

     7       i0,

     8       i1,

     9       tension = .7;

    10 

    11   function area(d) {

    12     if (d.length < 1) return null;

    13     var points0 = d3_svg_linePoints(this, d, x0, y0),

    14         points1 = d3_svg_linePoints(this, d, x0 === x1 ? d3_svg_areaX(points0) : x1, y0 === y1 ? d3_svg_areaY(points0) : y1);

    15     return "M" + i0(projection(points1), tension)

    16          + "L" + i1(projection(points0.reverse()), tension)

    17          + "Z";

    18   }

    19 

    20   area.x = function(x) {

    21     if (!arguments.length) return x1;

    22     x0 = x1 = x;

    23     return area;

    24   };

    25 

    26   area.x0 = function(x) {

    27     if (!arguments.length) return x0;

    28     x0 = x;

    29     return area;

    30   };

    31 

    32   area.x1 = function(x) {

    33     if (!arguments.length) return x1;

    34     x1 = x;

    35     return area;

    36   };

    37 

    38   area.y = function(y) {

    39     if (!arguments.length) return y1;

    40     y0 = y1 = y;

    41     return area;

    42   };

    43 

    44   area.y0 = function(y) {

    45     if (!arguments.length) return y0;

    46     y0 = y;

    47     return area;

    48   };

    49 

    50   area.y1 = function(y) {

    51     if (!arguments.length) return y1;

    52     y1 = y;

    53     return area;

    54   };

    55 

    56   area.interpolate = function(x) {

    57     if (!arguments.length) return interpolate;

    58     i0 = d3_svg_lineInterpolators[interpolate = x];

    59     i1 = i0.reverse || i0;

    60     return area;

    61   };

    62 

    63   area.tension = function(x) {

    64     if (!arguments.length) return tension;

    65     tension = x;

    66     return area;

    67   };

    68 

    69   return area.interpolate("linear");

    70 }

    71 

    72 d3_svg_lineStepBefore.reverse = d3_svg_lineStepAfter;

    73 d3_svg_lineStepAfter.reverse = d3_svg_lineStepBefore;

    74 

    75 d3.svg.area = function() {

    76   return d3_svg_area(Object);

    77 };

    78 

    79 function d3_svg_areaX(points) {

    80   return function(d, i) {

    81     return points[i][0];

    82   };

    83 }

    84 

    85 function d3_svg_areaY(points) {

    86   return function(d, i) {

    87     return points[i][1];

    88   };

    89 }