From a7fb35663c6868409790b2ccc2fb643c0bffe899 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Mon, 13 Oct 2014 16:46:32 -0700
Subject: [PATCH] Optimize Way#area

---
 js/id/core/way.js     | 10 +++++-----
 test/spec/core/way.js | 16 ++++++++++++++++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/js/id/core/way.js b/js/id/core/way.js
index 608cf7abf..44893ea87 100644
--- a/js/id/core/way.js
+++ b/js/id/core/way.js
@@ -218,20 +218,20 @@ _.extend(iD.Way.prototype, {
         return resolver.transient(this, 'area', function() {
             var nodes = resolver.childNodes(this);
 
-            if (!this.isClosed() && nodes.length) {
-                nodes = nodes.concat([nodes[0]]);
-            }
-
             var json = {
                 type: 'Polygon',
                 coordinates: [_.pluck(nodes, 'loc')]
             };
 
+            if (!this.isClosed() && nodes.length) {
+                json.coordinates[0].push(nodes[0].loc);
+            }
+
             var area = d3.geo.area(json);
 
             // Heuristic for detecting counterclockwise winding order. Assumes
             // that OpenStreetMap polygons are not hemisphere-spanning.
-            if (d3.geo.area(json) > 2 * Math.PI) {
+            if (area > 2 * Math.PI) {
                 json.coordinates[0] = json.coordinates[0].reverse();
                 area = d3.geo.area(json);
             }
diff --git a/test/spec/core/way.js b/test/spec/core/way.js
index 799b6a224..a551db1ce 100644
--- a/test/spec/core/way.js
+++ b/test/spec/core/way.js
@@ -469,6 +469,22 @@ describe('iD.Way', function() {
             expect(s).to.be.lt(l);
         });
 
+        it("treats unclosed areas as if they were closed", function () {
+            var graph = iD.Graph([
+                iD.Node({id: 'a', loc: [-0.0002,  0.0001]}),
+                iD.Node({id: 'b', loc: [ 0.0002,  0.0001]}),
+                iD.Node({id: 'c', loc: [ 0.0002, -0.0001]}),
+                iD.Node({id: 'd', loc: [-0.0002, -0.0001]}),
+                iD.Way({id: 's', tags: {area: 'yes'}, nodes: ['a', 'b', 'c', 'd', 'a']}),
+                iD.Way({id: 'l', tags: {area: 'yes'}, nodes: ['a', 'b', 'c', 'd']})
+            ]);
+
+            var s = graph.entity('s').area(graph),
+                l = graph.entity('l').area(graph);
+
+            expect(s).to.equal(l);
+        });
+
         it("returns 0 for degenerate areas", function () {
             var graph = iD.Graph([
                 iD.Node({id: 'a', loc: [-0.0002,  0.0001]}),