Fix quadtree find with accessors

d3.js

@@ -5638,7 +5638,7 @@
     (function find(node, x1, y1, x2, y2) {
       if (x1 > x3 || y1 > y3 || x2 < x0 || y2 < y0) return;
       if (point = node.point) {
-        var point, dx = x - point[0], dy = y - point[1], distance2 = dx * dx + dy * dy;
+        var point, dx = x - node.x, dy = y - node.y, distance2 = dx * dx + dy * dy;
         if (distance2 < minDistance2) {
           var distance = Math.sqrt(minDistance2 = distance2);
           x0 = x - distance, y0 = y - distance;

src/geom/quadtree.js

@@ -210,8 +210,8 @@ function d3_geom_quadtreeFind(root, x, y, x0, y0, x3, y3) {
     // visit this point
     if (point = node.point) {
       var point,
-          dx = x - point[0],
-          dy = y - point[1],
+          dx = x - node.x,
+          dy = y - node.y,
           distance2 = dx * dx + dy * dy;
       if (distance2 < minDistance2) {
         var distance = Math.sqrt(minDistance2 = distance2);

test/geom/quadtree-test.js

@@ -47,6 +47,14 @@ suite.addBatch({
         assert.deepEqual(q.find([7.5, 7.5]), [7, 7]);
         assert.deepEqual(q.find([.1, 15.9]), [0, 16]);
         assert.deepEqual(q.find([15.9, 15.9]), [16, 16]);
+      },
+      "can find with accessors": function(q) {
+        q.x(function(d) { return d.x; });
+        q.y(function(d) { return d.y; });
+
+        var point = {x: 0, y: 0, arbitrary: 1};
+        q = q([point]);
+        assert.deepEqual(q.find([0, 0]), point);
       }
     },
     "the quadtree applied directly": {