From 048a9ab10c0ae7ab85679eca39a24f0dc5640dfd Mon Sep 17 00:00:00 2001
From: Steffen Matthischke <steffen.matthischke@lovoo.com>
Date: Fri, 14 Jul 2017 20:54:46 -0700
Subject: [PATCH] RCTScrollEvent: get all required values injected rather than
 accessing the scroll view

Summary:
This PR fixes #15006 by removing all UI API calls from RCTScrollEvent.

`-[RCTScrollEvent arguments]` can now be called from a background thread.
The Main Thread Checker of Xcode 9 will not any longer produce runtime issues when calling this method.

1. create a React Native (version: this PR) project with a scroll view
2. open it in Xcode 9
3. launch it
4. scroll the scroll view
5. observe the runtime issues in Xcode. There should not contain "UI API called from background thread"-issues.

I verified my changes on this branch: https://github.com/HeEAaD/Demo-ReactNative-UI-not-on-main-thread/tree/fix

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Closes https://github.com/facebook/react-native/pull/15008

Differential Revision: D5424734

Pulled By: shergin

fbshipit-source-id: 56beec2d7603ea6782d55622567509f3758a4517
---
 React/Views/RCTScrollView.m | 58 ++++++++++++++++++++++++++-----------
 1 file changed, 41 insertions(+), 17 deletions(-)

diff --git a/React/Views/RCTScrollView.m b/React/Views/RCTScrollView.m
index 0035da12872..9c4be9d6ff5 100644
--- a/React/Views/RCTScrollView.m
+++ b/React/Views/RCTScrollView.m
@@ -27,7 +27,11 @@
 
 - (instancetype)initWithEventName:(NSString *)eventName
                          reactTag:(NSNumber *)reactTag
-                       scrollView:(UIScrollView *)scrollView
+          scrollViewContentOffset:(CGPoint)scrollViewContentOffset
+           scrollViewContentInset:(UIEdgeInsets)scrollViewContentInset
+            scrollViewContentSize:(CGSize)scrollViewContentSize
+                  scrollViewFrame:(CGRect)scrollViewFrame
+              scrollViewZoomScale:(CGFloat)scrollViewZoomScale
                          userData:(NSDictionary *)userData
                     coalescingKey:(uint16_t)coalescingKey NS_DESIGNATED_INITIALIZER;
 
@@ -35,7 +39,11 @@
 
 @implementation RCTScrollEvent
 {
-  UIScrollView *_scrollView;
+  CGPoint _scrollViewContentOffset;
+  UIEdgeInsets _scrollViewContentInset;
+  CGSize _scrollViewContentSize;
+  CGRect _scrollViewFrame;
+  CGFloat _scrollViewZoomScale;
   NSDictionary *_userData;
   uint16_t _coalescingKey;
 }
@@ -45,7 +53,11 @@
 
 - (instancetype)initWithEventName:(NSString *)eventName
                          reactTag:(NSNumber *)reactTag
-                       scrollView:(UIScrollView *)scrollView
+          scrollViewContentOffset:(CGPoint)scrollViewContentOffset
+           scrollViewContentInset:(UIEdgeInsets)scrollViewContentInset
+            scrollViewContentSize:(CGSize)scrollViewContentSize
+                  scrollViewFrame:(CGRect)scrollViewFrame
+              scrollViewZoomScale:(CGFloat)scrollViewZoomScale
                          userData:(NSDictionary *)userData
                     coalescingKey:(uint16_t)coalescingKey
 {
@@ -54,7 +66,11 @@
   if ((self = [super init])) {
     _eventName = [eventName copy];
     _viewTag = reactTag;
-    _scrollView = scrollView;
+    _scrollViewContentOffset = scrollViewContentOffset;
+    _scrollViewContentInset = scrollViewContentInset;
+    _scrollViewContentSize = scrollViewContentSize;
+    _scrollViewFrame = scrollViewFrame;
+    _scrollViewZoomScale = scrollViewZoomScale;
     _userData = userData;
     _coalescingKey = coalescingKey;
   }
@@ -72,24 +88,24 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 {
   NSDictionary *body = @{
     @"contentOffset": @{
-      @"x": @(_scrollView.contentOffset.x),
-      @"y": @(_scrollView.contentOffset.y)
+      @"x": @(_scrollViewContentOffset.x),
+      @"y": @(_scrollViewContentOffset.y)
     },
     @"contentInset": @{
-      @"top": @(_scrollView.contentInset.top),
-      @"left": @(_scrollView.contentInset.left),
-      @"bottom": @(_scrollView.contentInset.bottom),
-      @"right": @(_scrollView.contentInset.right)
+      @"top": @(_scrollViewContentInset.top),
+      @"left": @(_scrollViewContentInset.left),
+      @"bottom": @(_scrollViewContentInset.bottom),
+      @"right": @(_scrollViewContentInset.right)
     },
     @"contentSize": @{
-      @"width": @(_scrollView.contentSize.width),
-      @"height": @(_scrollView.contentSize.height)
+      @"width": @(_scrollViewContentSize.width),
+      @"height": @(_scrollViewContentSize.height)
     },
     @"layoutMeasurement": @{
-      @"width": @(_scrollView.frame.size.width),
-      @"height": @(_scrollView.frame.size.height)
+      @"width": @(_scrollViewFrame.size.width),
+      @"height": @(_scrollViewFrame.size.height)
     },
-    @"zoomScale": @(_scrollView.zoomScale ?: 1),
+    @"zoomScale": @(_scrollViewZoomScale ?: 1),
   };
 
   if (_userData) {
@@ -893,7 +909,11 @@ RCT_SET_AND_PRESERVE_OFFSET(setScrollIndicatorInsets, scrollIndicatorInsets, UIE
   }
   RCTScrollEvent *scrollEvent = [[RCTScrollEvent alloc] initWithEventName:eventName
                                                                  reactTag:self.reactTag
-                                                               scrollView:scrollView
+                                                  scrollViewContentOffset:scrollView.contentOffset
+                                                   scrollViewContentInset:scrollView.contentInset
+                                                    scrollViewContentSize:scrollView.contentSize
+                                                          scrollViewFrame:scrollView.frame
+                                                      scrollViewZoomScale:scrollView.zoomScale
                                                                  userData:userData
                                                             coalescingKey:_coalescingKey];
   [_eventDispatcher sendEvent:scrollEvent];
@@ -909,7 +929,11 @@ RCT_SET_AND_PRESERVE_OFFSET(setScrollIndicatorInsets, scrollIndicatorInsets, UIE
   NSString *eventName = NSStringFromSelector(@selector(onScroll));
   RCTScrollEvent *fakeScrollEvent = [[RCTScrollEvent alloc] initWithEventName:eventName
                                                                      reactTag:reactTag
-                                                                   scrollView:nil
+                                                      scrollViewContentOffset:CGPointZero
+                                                       scrollViewContentInset:UIEdgeInsetsZero
+                                                        scrollViewContentSize:CGSizeZero
+                                                              scrollViewFrame:CGRectZero
+                                                          scrollViewZoomScale:0
                                                                      userData:nil
                                                                 coalescingKey:0];
   [self sendEvent:fakeScrollEvent];