From 4d40a4f962f032c25c8a446f0512b213a39c12e0 Mon Sep 17 00:00:00 2001
From: Grant Berridge <grantyb@gmail.com>
Date: Thu, 17 Oct 2013 15:24:24 +1300
Subject: [PATCH] Fix ngShow and ngHide so that the directives don't animate
 in/out their classes every time the watch expression is evaluated.  They now
 only change when the watch expression's boolean value actually changes.

This is to address issue #4401
---
 src/ng/directive/ngShowHide.js | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/ng/directive/ngShowHide.js b/src/ng/directive/ngShowHide.js
index cdfa060421ca..bd1f7a6ffdbb 100644
--- a/src/ng/directive/ngShowHide.js
+++ b/src/ng/directive/ngShowHide.js
@@ -145,8 +145,12 @@
  */
 var ngShowDirective = ['$animate', function($animate) {
   return function(scope, element, attr) {
-    scope.$watch(attr.ngShow, function ngShowWatchAction(value){
-      $animate[toBoolean(value) ? 'removeClass' : 'addClass'](element, 'ng-hide');
+    var watchHasNeverFired = true;
+    scope.$watch(attr.ngShow, function ngShowWatchAction(value, oldValue){
+      if (watchHasNeverFired || (toBoolean(value) !== toBoolean(oldValue))) {
+        watchHasNeverFired = false;
+        $animate[toBoolean(value) ? 'removeClass' : 'addClass'](element, 'ng-hide');
+      }
     });
   };
 }];
@@ -297,8 +301,11 @@ var ngShowDirective = ['$animate', function($animate) {
  */
 var ngHideDirective = ['$animate', function($animate) {
   return function(scope, element, attr) {
-    scope.$watch(attr.ngHide, function ngHideWatchAction(value){
-      $animate[toBoolean(value) ? 'addClass' : 'removeClass'](element, 'ng-hide');
+    var watchHasNeverFired = true;
+    scope.$watch(attr.ngHide, function ngHideWatchAction(value, oldValue){
+      if (watchHasNeverFired || (toBoolean(value) !== toBoolean(oldValue))) {
+        $animate[toBoolean(value) ? 'addClass' : 'removeClass'](element, 'ng-hide');
+      }
     });
   };
 }];