--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/svg/diagonal.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,38 @@
+d3.svg.diagonal = function() {
+  var source = d3_svg_chordSource,
+      target = d3_svg_chordTarget,
+      projection = d3_svg_diagonalProjection;
+
+  function diagonal(d, i) {
+    var p0 = source.call(this, d, i),
+        p3 = target.call(this, d, i),
+        m = (p0.y + p3.y) / 2,
+        p = [p0, {x: p0.x, y: m}, {x: p3.x, y: m}, p3];
+    p = p.map(projection);
+    return "M" + p[0] + "C" + p[1] + " " + p[2] + " " + p[3];
+  }
+
+  diagonal.source = function(x) {
+    if (!arguments.length) return source;
+    source = d3.functor(x);
+    return diagonal;
+  };
+
+  diagonal.target = function(x) {
+    if (!arguments.length) return target;
+    target = d3.functor(x);
+    return diagonal;
+  };
+
+  diagonal.projection = function(x) {
+    if (!arguments.length) return projection;
+    projection = x;
+    return diagonal;
+  };
+
+  return diagonal;
+};
+
+function d3_svg_diagonalProjection(d) {
+  return [d.x, d.y];
+}