Fix extent and difference rendering for multi polygons

js/id/graph/relation.js

@@ -2,8 +2,14 @@ iD.Relation = iD.Entity.extend({
     type: "relation",
     members: [],
 
-    extent: function() {
-        return [[NaN, NaN], [NaN, NaN]];
+    extent: function(resolver) {
+        return resolver.transient(this, 'extent', function() {
+            var extent = iD.geo.Extent();
+            for (var i = 0, l = this.members.length; i < l; i++) {
+                extent = extent.extend(resolver.entity(this.members[i].id).extent(resolver));
+            }
+            return extent;
+        });
     },
 
     geometry: function() {

js/id/renderer/map.js

@@ -69,8 +69,7 @@ iD.Map = function() {
             all = graph.intersects(extent);
             filter = d3.functor(true);
         } else {
-            var only = {},
-                filterOnly = {};
+            var only = {};
             for (var j = 0; j < difference.length; j++) {
                 var id = difference[j],
                     entity = graph.fetch(id);
@@ -86,6 +85,13 @@ iD.Map = function() {
                                 only[parents[k].id] = graph.fetch(parents[k].id);
                             }
                         }
+                        parents = graph.parentRelations(only[id]);
+                        for (k = 0; k < parents.length; k++) {
+                            // Don't re-fetch parents
+                            if (only[parents[k].id] === undefined) {
+                                only[parents[k].id] = parents[k].id;
+                            }
+                        }
                     }
                 }
             }

test/spec/graph/relation.js

@@ -36,7 +36,14 @@ describe('iD.Relation', function () {
     });
 
     describe("#extent", function () {
-        it("returns the minimal extent containing the extents of all members");
+        it("returns the minimal extent containing the extents of all members", function () {
+            var a = iD.Node({loc: [0, 0]}),
+                b = iD.Node({loc: [5, 10]}),
+                r = iD.Relation({members: [{id: a.id}, {id: b.id}]}),
+                graph = iD.Graph([a, b, r]);
+
+            expect(r.extent(graph)).to.eql([[0, 0], [5, 10]])
+        });
     });
 
     describe("#multipolygon", function () {