From a460a0264a949ae771d740aee29f9734a0f70f9a Mon Sep 17 00:00:00 2001
From: Trey Smith <trey.smith@nasa.gov>
Date: Wed, 17 Oct 2012 13:17:06 -0700
Subject: [PATCH] undo.js: check whether state changed before pushing onto undo
 stack

---
 geocamTiePoint/static/geocamTiePoint/js/undo.js | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/geocamTiePoint/static/geocamTiePoint/js/undo.js b/geocamTiePoint/static/geocamTiePoint/js/undo.js
index e91318f..84c8a8a 100644
--- a/geocamTiePoint/static/geocamTiePoint/js/undo.js
+++ b/geocamTiePoint/static/geocamTiePoint/js/undo.js
@@ -33,7 +33,19 @@ function setStateJson(stateJson) {
 }
 
 function pushState(stack) {
-    stack.push(getStateJson());
+    var json = getStateJson();
+
+    var isNew;
+    if (undoStackG.length < 1) {
+        isNew = true;
+    } else {
+        var prev = undoStackG[undoStackG.length - 1];
+        isNew = (prev != json);
+    }
+    if (isNew) {
+        stack.push(json);
+    }
+    return isNew;
 }
 
 function popState(stack) {
@@ -58,6 +70,5 @@ function actionPerformed() {
             undoStackG.push(redoStackG.pop());
         }
     }
-    pushState(undoStackG);
+    return pushState(undoStackG);
 }
-