Add d3.geom.lengthSink.

mbostock · mbostock · commit ee4c7db07d60 · 2014-09-26T14:15:31.000-07:00
diff --git a/d3.js b/d3.js
@@ -4732,6 +4732,51 @@
       }
     };
   };
+  d3.geom.lengthSink = function() {
+    var x00, y00, x0, y0, sum = 0;
+    var sink = {
+      point: d3_noop,
+      lineStart: lineStart,
+      lineEnd: lineEnd,
+      polygonStart: polygonStart,
+      polygonEnd: polygonEnd,
+      value: value
+    };
+    function pointLineStart(x, y) {
+      x00 = x0 = x;
+      y00 = y0 = y;
+      sink.point = pointLine;
+    }
+    function pointLine(x, y) {
+      var dx = x - x0, dy = y - y0;
+      x0 = x;
+      y0 = y;
+      sum += Math.sqrt(dx * dx + dy * dy);
+    }
+    function lineStart() {
+      sink.point = pointLineStart;
+    }
+    function lineEnd() {
+      x00 = y00 = x0 = y0 = undefined;
+      sink.point = d3_noop;
+    }
+    function lineEndPolygon() {
+      pointLine(x00, y00);
+      lineEnd();
+    }
+    function polygonStart() {
+      sink.lineEnd = lineEndPolygon;
+    }
+    function polygonEnd() {
+      sink.lineEnd = lineEnd;
+    }
+    function value() {
+      var value = sum;
+      sum = 0;
+      return value;
+    }
+    return sink;
+  };
   d3.geom.matrix = function(a, b, c, d, e, f, sink) {
     return {
       polygonStart: function() {
diff --git a/d3.min.js b/d3.min.js
diff --git a/src/geom/index.js b/src/geom/index.js
@@ -9,5 +9,6 @@ import "json-source";
 import "context-sink";
 import "path-sink";
 import "bounds-sink";
+import "length-sink";
 import "matrix";
 import "clip-extent";
diff --git a/src/geom/length-sink.js b/src/geom/length-sink.js
@@ -0,0 +1,63 @@
+import "../core/noop";
+import "geom";
+
+d3.geom.lengthSink = function() {
+  var x00,
+      y00,
+      x0,
+      y0,
+      sum = 0;
+
+  var sink = {
+    point: d3_noop,
+    lineStart: lineStart,
+    lineEnd: lineEnd,
+    polygonStart: polygonStart,
+    polygonEnd: polygonEnd,
+    value: value
+  };
+
+  function pointLineStart(x, y) {
+    x00 = x0 = x;
+    y00 = y0 = y;
+    sink.point = pointLine;
+  }
+
+  function pointLine(x, y) {
+    var dx = x - x0,
+        dy = y - y0;
+    x0 = x;
+    y0 = y;
+    sum += Math.sqrt(dx * dx + dy * dy);
+  }
+
+  function lineStart() {
+    sink.point = pointLineStart;
+  }
+
+  function lineEnd() {
+    x00 = y00 = x0 = y0 = undefined;
+    sink.point = d3_noop;
+  }
+
+  function lineEndPolygon() {
+    pointLine(x00, y00);
+    lineEnd();
+  }
+
+  function polygonStart() {
+    sink.lineEnd = lineEndPolygon;
+  }
+
+  function polygonEnd() {
+    sink.lineEnd = lineEnd;
+  }
+
+  function value() {
+    var value = sum;
+    sum = 0;
+    return value;
+  }
+
+  return sink;
+};
