Clarify how connections have graphs, don't build big arrays in memory

index.html

@@ -63,9 +63,7 @@
         Imagery <a href="http://opengeodata.org/microsoft-imagery-details">&copy; 2012</a> Bing, GeoEye, Getmapping, Intermap, Microsoft.</p>
     </div>
 <script>
-    var connection = new iD.Connection("http://www.overpass-api.de/api/xapi?");
-    var graph = new iD.Graph();
-    connection.graph(graph);
+    var connection = new iD.Connection(new iD.Graph());
 
     var m = d3.select('#map');
     // Initialise map

js/iD/Connection.js

@@ -1,10 +1,9 @@
-iD.Connection = function() {
+iD.Connection = function(graph) {
     // summary:	The data store, including methods to fetch data from (and, eventually, save data to)
     // an OSM API server.
     var nextNode = -1,
         nextWay = -1,
         nextRelation = -1,
-        graph = {},
         apiURL = 'http://www.openstreetmap.org/api/0.6/';
 
     var connection = {};
@@ -99,12 +98,7 @@ iD.Connection = function() {
         };
     }
 
-    connection.graph = function(x) {
-        if (!arguments.length) return graph;
-        graph = x;
-        return connection;
-    };
-
+    connection.graph = graph;
     connection.all = all;
     connection.loadFromAPI = loadFromAPI;
     connection.loadFromURL = loadFromURL;

js/iD/renderer/Map.js

@@ -18,8 +18,14 @@ iD.Map = function(obj) {
     var inspector = iD.Inspector();
 
     var linegen = d3.svg.line()
-        .x(function(d) { return projection(d)[0]; })
-        .y(function(d) { return projection(d)[1]; });
+        .x(function(d) {
+            var node = connection.graph.index[d];
+            return projection([node.lon, node.lat])[0];
+        })
+        .y(function(d) {
+            var node = connection.graph.index[d];
+            return projection([node.lon, node.lat])[1];
+        });
 
     var zoombehavior = d3.behavior.zoom()
         .translate(projection.translate())
@@ -112,10 +118,7 @@ iD.Map = function(obj) {
     }
 
     function nodeline(d) {
-        return linegen(d.children.map(function(n) {
-            var node = connection.graph().index[n];
-            return [node.lon, node.lat];
-        }));
+        return linegen(d.children);
     }
 
     // This is an unfortunate hack that should be improved.