diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/src/svg/chord.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/svg/chord.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,99 @@
+d3.svg.chord = function() {
+  var source = d3_svg_chordSource,
+      target = d3_svg_chordTarget,
+      radius = d3_svg_chordRadius,
+      startAngle = d3_svg_arcStartAngle,
+      endAngle = d3_svg_arcEndAngle;
+
+  // TODO Allow control point to be customized.
+
+  function chord(d, i) {
+    var s = subgroup(this, source, d, i),
+        t = subgroup(this, target, d, i);
+    return "M" + s.p0
+      + arc(s.r, s.p1) + (equals(s, t)
+      ? curve(s.r, s.p1, s.r, s.p0)
+      : curve(s.r, s.p1, t.r, t.p0)
+      + arc(t.r, t.p1)
+      + curve(t.r, t.p1, s.r, s.p0))
+      + "Z";
+  }
+
+  function subgroup(self, f, d, i) {
+    var subgroup = f.call(self, d, i),
+        r = radius.call(self, subgroup, i),
+        a0 = startAngle.call(self, subgroup, i) + d3_svg_arcOffset,
+        a1 = endAngle.call(self, subgroup, i) + d3_svg_arcOffset;
+    return {
+      r: r,
+      a0: a0,
+      a1: a1,
+      p0: [r * Math.cos(a0), r * Math.sin(a0)],
+      p1: [r * Math.cos(a1), r * Math.sin(a1)]
+    };
+  }
+
+  function equals(a, b) {
+    return a.a0 == b.a0 && a.a1 == b.a1;
+  }
+
+  function arc(r, p) {
+    return "A" + r + "," + r + " 0 0,1 " + p;
+  }
+
+  function curve(r0, p0, r1, p1) {
+    return "Q 0,0 " + p1;
+  }
+
+  chord.radius = function(v) {
+    if (!arguments.length) return radius;
+    radius = d3.functor(v);
+    return chord;
+  };
+
+  chord.source = function(v) {
+    if (!arguments.length) return source;
+    source = d3.functor(v);
+    return chord;
+  };
+
+  chord.target = function(v) {
+    if (!arguments.length) return target;
+    target = d3.functor(v);
+    return chord;
+  };
+
+  chord.startAngle = function(v) {
+    if (!arguments.length) return startAngle;
+    startAngle = d3.functor(v);
+    return chord;
+  };
+
+  chord.endAngle = function(v) {
+    if (!arguments.length) return endAngle;
+    endAngle = d3.functor(v);
+    return chord;
+  };
+
+  return chord;
+};
+
+function d3_svg_chordSource(d) {
+  return d.source;
+}
+
+function d3_svg_chordTarget(d) {
+  return d.target;
+}
+
+function d3_svg_chordRadius(d) {
+  return d.radius;
+}
+
+function d3_svg_chordStartAngle(d) {
+  return d.startAngle;
+}
+
+function d3_svg_chordEndAngle(d) {
+  return d.endAngle;
+}