From c5c65ccdfd6c421424a3153afcf3ae64d5e73198 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Fri, 7 Dec 2012 12:29:17 -0500
Subject: [PATCH] Include difference in history change events

---
 js/id/graph/history.js     | 26 ++++++++++++++++++--------
 test/spec/graph/history.js |  8 ++++----
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/js/id/graph/history.js b/js/id/graph/history.js
index 683b0af16..21c1d9326 100644
--- a/js/id/graph/history.js
+++ b/js/id/graph/history.js
@@ -19,10 +19,8 @@ iD.History = function() {
         return {graph: graph, annotation: annotation};
     }
 
-    function maybeChange() {
-        if (stack[index].annotation) {
-            dispatch.change();
-        }
+    function change(previous) {
+        dispatch.change(history.graph().difference(previous));
     }
 
     var history = {
@@ -37,32 +35,44 @@ iD.History = function() {
         },
 
         perform: function () {
+            var previous = stack[index].graph;
+
             stack = stack.slice(0, index + 1);
             stack.push(perform(arguments));
             index++;
-            dispatch.change();
+
+            change(previous);
         },
 
         replace: function () {
+            var previous = stack[index].graph;
+
             // assert(index == stack.length - 1)
             stack[index] = perform(arguments);
-            dispatch.change();
+
+            change(previous);
         },
 
         undo: function () {
+            var previous = stack[index].graph;
+
             while (index > 0) {
                 index--;
                 if (stack[index].annotation) break;
             }
-            dispatch.change();
+
+            change(previous);
         },
 
         redo: function () {
+            var previous = stack[index].graph;
+
             while (index < stack.length - 1) {
                 index++;
                 if (stack[index].annotation) break;
             }
-            dispatch.change();
+
+            change(previous);
         },
 
         undoAnnotation: function () {
diff --git a/test/spec/graph/history.js b/test/spec/graph/history.js
index be7237292..15fe10964 100644
--- a/test/spec/graph/history.js
+++ b/test/spec/graph/history.js
@@ -28,7 +28,7 @@ describe("iD.History", function () {
         it("emits a change event", function () {
             history.on('change', spy);
             history.perform(action);
-            expect(spy).to.have.been.called;
+            expect(spy).to.have.been.calledWith([]);
         });
 
         it("performs multiple actions", function () {
@@ -57,7 +57,7 @@ describe("iD.History", function () {
         it("emits a change event", function () {
             history.on('change', spy);
             history.replace(action);
-            expect(spy).to.have.been.called;
+            expect(spy).to.have.been.calledWith([]);
         });
 
         it("performs multiple actions", function () {
@@ -87,7 +87,7 @@ describe("iD.History", function () {
             history.perform(action);
             history.on('change', spy);
             history.undo();
-            expect(spy).to.have.been.called;
+            expect(spy).to.have.been.calledWith([]);
         });
     });
 
@@ -97,7 +97,7 @@ describe("iD.History", function () {
             history.undo();
             history.on('change', spy);
             history.redo();
-            expect(spy).to.have.been.called;
+            expect(spy).to.have.been.calledWith([]);
         });
     });