From baed197a7d1140b423e7e728b5b48b2b01069534 Mon Sep 17 00:00:00 2001
From: Andy Street <andrews@fb.com>
Date: Thu, 16 Apr 2015 14:50:00 -0700
Subject: [PATCH] [react_native] JS files from D1998038:     [react_native]
 Calculate density independent screen size in JS to prevent loss of precision

---
 Libraries/Utilities/Dimensions.js | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Libraries/Utilities/Dimensions.js b/Libraries/Utilities/Dimensions.js
index 80d564a2b..c7302c7c5 100644
--- a/Libraries/Utilities/Dimensions.js
+++ b/Libraries/Utilities/Dimensions.js
@@ -17,6 +17,26 @@ var invariant = require('invariant');
 
 var dimensions = NativeModules.UIManager.Dimensions;
 
+// We calculate the window dimensions in JS so that we don't encounter loss of
+// precision in transferring the dimensions (which could be non-integers) over
+// the bridge.
+if (dimensions.windowPhysicalPixels) {
+  // parse/stringify => Clone hack
+  dimensions = JSON.parse(JSON.stringify(dimensions));
+
+  var windowPhysicalPixels = dimensions.windowPhysicalPixels;
+  dimensions.window = {
+    width: windowPhysicalPixels.width / windowPhysicalPixels.scale,
+    height: windowPhysicalPixels.height / windowPhysicalPixels.scale,
+    scale: windowPhysicalPixels.scale,
+  };
+  // TODO(andrews): Remove modalFullscreenView
+  dimensions.modalFullscreenView = dimensions.window;
+
+  // delete so no callers rely on this existing
+  delete dimensions.windowPhysicalPixels;
+}
+
 class Dimensions {
   /**
    * This should only be called from native code.