From 61da183c59b6b1e3a9e521c0793be2a87f9c536e Mon Sep 17 00:00:00 2001
From: Howard Yeh <howard@metacircus.com>
Date: Tue, 26 Apr 2016 21:49:26 -0700
Subject: [PATCH] Android shouldn't dispatch onLayout if frame didn't change

---
 .../react/uimanager/ReactShadowNode.java      | 25 +++++++++++++++----
 .../react/uimanager/UIImplementation.java     |  4 +--
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java
index df8ad675d294..b3089d1e0ed1 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/ReactShadowNode.java
@@ -191,7 +191,7 @@ public void onAfterUpdateTransaction() {
   public void onCollectExtraUpdates(UIViewOperationQueue uiViewOperationQueue) {
   }
 
-  /* package */ void dispatchUpdates(
+  /* package */ boolean dispatchUpdates(
       float absoluteX,
       float absoluteY,
       UIViewOperationQueue uiViewOperationQueue,
@@ -201,12 +201,27 @@ public void onCollectExtraUpdates(UIViewOperationQueue uiViewOperationQueue) {
     }
 
     if (hasNewLayout()) {
-      mAbsoluteLeft = Math.round(absoluteX + getLayoutX());
-      mAbsoluteTop = Math.round(absoluteY + getLayoutY());
-      mAbsoluteRight = Math.round(absoluteX + getLayoutX() + getLayoutWidth());
-      mAbsoluteBottom = Math.round(absoluteY + getLayoutY() + getLayoutHeight());
+      float newLeft = Math.round(absoluteX + getLayoutX());
+      float newTop = Math.round(absoluteY + getLayoutY());
+      float newRight = Math.round(absoluteX + getLayoutX() + getLayoutWidth());
+      float newBottom = Math.round(absoluteY + getLayoutY() + getLayoutHeight());
+
+      if (newLeft == mAbsoluteLeft &&
+          newRight == mAbsoluteRight &&
+          newTop == mAbsoluteTop &&
+          newBottom == mAbsoluteBottom) {
+        return false;
+      }
+
+      mAbsoluteLeft = newLeft;
+      mAbsoluteTop = newTop;
+      mAbsoluteRight = newRight;
+      mAbsoluteBottom = newBottom;
 
       nativeViewHierarchyOptimizer.handleUpdateLayout(this);
+      return true;
+    } else {
+      return false;
     }
   }
 
diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java
index 20df2a161eb4..a8335a924a9d 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIImplementation.java
@@ -755,14 +755,14 @@ protected void applyUpdatesRecursive(
 
     int tag = cssNode.getReactTag();
     if (!mShadowNodeRegistry.isRootNode(tag)) {
-      cssNode.dispatchUpdates(
+      boolean frameDidChange = cssNode.dispatchUpdates(
           absoluteX,
           absoluteY,
           mOperationsQueue,
           mNativeViewHierarchyOptimizer);
 
       // notify JS about layout event if requested
-      if (cssNode.shouldNotifyOnLayout()) {
+      if (frameDidChange && cssNode.shouldNotifyOnLayout()) {
         eventDispatcher.dispatchEvent(
             OnLayoutEvent.obtain(
                 tag,