From 21c3931b697c29ad5509226866960f987d918be0 Mon Sep 17 00:00:00 2001
From: Nicolas Gallagher <nicolasgallagher@gmail.com>
Date: Tue, 1 Jan 2019 12:21:29 -0800
Subject: [PATCH] [fix] use getBoundingClientRect to measure layout

Fix #1037
Fix #1151
---
 .../src/exports/UIManager/index.js            | 20 +++++++-----------
 .../modules/getBoundingClientRect/index.js    | 21 +++++++++++++++++++
 .../src/modules/normalizeNativeEvent/index.js | 19 ++++++-----------
 3 files changed, 35 insertions(+), 25 deletions(-)
 create mode 100644 packages/react-native-web/src/modules/getBoundingClientRect/index.js

diff --git a/packages/react-native-web/src/exports/UIManager/index.js b/packages/react-native-web/src/exports/UIManager/index.js
index 20b1fca56..7bfb605bd 100644
--- a/packages/react-native-web/src/exports/UIManager/index.js
+++ b/packages/react-native-web/src/exports/UIManager/index.js
@@ -7,28 +7,24 @@
  * @noflow
  */
 
+import getBoundingClientRect from '../../modules/getBoundingClientRect';
 import setValueForStyles from '../../vendor/react-dom/setValueForStyles';
 
 const getRect = node => {
-  const height = node.offsetHeight;
+  // Unlike the DOM's getBoundingClientRect, React Native layout measurements
+  // for "height" and "width" ignore scale transforms.
+  // https://developer.mozilla.org/en-US/docs/Web/API/CSS_Object_Model/Determining_the_dimensions_of_elements
+  const { x, y, top, left } = getBoundingClientRect(node);
   const width = node.offsetWidth;
-  let left = node.offsetLeft;
-  let top = node.offsetTop;
-  node = node.offsetParent;
-
-  while (node && node.nodeType === 1 /* Node.ELEMENT_NODE */) {
-    left += node.offsetLeft - node.scrollLeft;
-    top += node.offsetTop - node.scrollTop;
-    node = node.offsetParent;
-  }
-  return { height, left, top, width };
+  const height = node.offsetHeight;
+  return { x, y, width, height, top, left };
 };
 
 const measureLayout = (node, relativeToNativeNode, callback) => {
   const relativeNode = relativeToNativeNode || (node && node.parentNode);
   if (node && relativeNode) {
     setTimeout(() => {
-      const relativeRect = getRect(relativeNode);
+      const relativeRect = getBoundingClientRect(relativeNode);
       const { height, left, top, width } = getRect(node);
       const x = left - relativeRect.left;
       const y = top - relativeRect.top;
diff --git a/packages/react-native-web/src/modules/getBoundingClientRect/index.js b/packages/react-native-web/src/modules/getBoundingClientRect/index.js
new file mode 100644
index 000000000..d81aa7610
--- /dev/null
+++ b/packages/react-native-web/src/modules/getBoundingClientRect/index.js
@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) 2015-present, Nicolas Gallagher.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ */
+
+/* global HTMLElement */
+
+const getBoundingClientRect = (node: HTMLElement) => {
+  if (node) {
+    const isElement = node.nodeType === 1; /* Node.ELEMENT_NODE */
+    if (isElement && typeof node.getBoundingClientRect === 'function') {
+      return node.getBoundingClientRect();
+    }
+  }
+};
+
+export default getBoundingClientRect;
diff --git a/packages/react-native-web/src/modules/normalizeNativeEvent/index.js b/packages/react-native-web/src/modules/normalizeNativeEvent/index.js
index 126dd0992..f6368d296 100644
--- a/packages/react-native-web/src/modules/normalizeNativeEvent/index.js
+++ b/packages/react-native-web/src/modules/normalizeNativeEvent/index.js
@@ -7,18 +7,11 @@
  * @flow
  */
 
+import getBoundingClientRect from '../getBoundingClientRect';
+
 const emptyArray = [];
 const emptyFunction = () => {};
 
-const getRect = node => {
-  if (node) {
-    const isElement = node.nodeType === 1 /* Node.ELEMENT_NODE */;
-    if (isElement && typeof node.getBoundingClientRect === 'function') {
-      return node.getBoundingClientRect();
-    }
-  }
-};
-
 // Mobile Safari re-uses touch objects, so we copy the properties we want and normalize the identifier
 const normalizeTouches = touches => {
   if (!touches) {
@@ -35,13 +28,13 @@ const normalizeTouches = touches => {
       clientY: touch.clientY,
       force: touch.force,
       get locationX() {
-        rect = rect || getRect(touch.target);
+        rect = rect || getBoundingClientRect(touch.target);
         if (rect) {
           return touch.pageX - rect.left;
         }
       },
       get locationY() {
-        rect = rect || getRect(touch.target);
+        rect = rect || getBoundingClientRect(touch.target);
         if (rect) {
           return touch.pageY - rect.top;
         }
@@ -121,13 +114,13 @@ function normalizeMouseEvent(nativeEvent) {
       force: nativeEvent.force,
       identifier: 0,
       get locationX() {
-        rect = rect || getRect(nativeEvent.target);
+        rect = rect || getBoundingClientRect(nativeEvent.target);
         if (rect) {
           return nativeEvent.pageX - rect.left;
         }
       },
       get locationY() {
-        rect = rect || getRect(nativeEvent.target);
+        rect = rect || getBoundingClientRect(nativeEvent.target);
         if (rect) {
           return nativeEvent.pageY - rect.top;
         }