From 42c8dead621c80f25ef0980466e0ff7902af2913 Mon Sep 17 00:00:00 2001
From: Samuel Susla <samuelsusla@fb.com>
Date: Fri, 3 Jul 2020 11:13:12 -0700
Subject: [PATCH] Restore contentOffset from state if necesarry

Summary:
Changelog: [Internal]

When JS Inspector is activated, ScrollView is unmounted and then mounted again with same state.

 ScrollView's content offset was being set to 0 inside `[RCTScrollViewComponentView prepareForRecycle]` during unmount but when it is mounted again, we ignored value inside state.

Reviewed By: shergin

Differential Revision: D22333125

fbshipit-source-id: f232dc95b695605f4819f29d8e0bf14b2f3e9150
---
 .../ScrollView/RCTScrollViewComponentView.mm              | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm b/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
index 8bbbb5118bc..3671801f14b 100644
--- a/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
+++ b/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
@@ -201,8 +201,14 @@ void RCTSetEnableOnDemandViewMounting(BOOL value)
 {
   assert(std::dynamic_pointer_cast<ScrollViewShadowNode::ConcreteState const>(state));
   _state = std::static_pointer_cast<ScrollViewShadowNode::ConcreteState const>(state);
+  auto &data = _state->getData();
 
-  CGSize contentSize = RCTCGSizeFromSize(_state->getData().getContentSize());
+  auto contentOffset = RCTCGPointFromPoint(data.contentOffset);
+  if (!oldState && !CGPointEqualToPoint(contentOffset, CGPointZero)) {
+    _scrollView.contentOffset = contentOffset;
+  }
+
+  CGSize contentSize = RCTCGSizeFromSize(data.getContentSize());
 
   if (CGSizeEqualToSize(_contentSize, contentSize)) {
     return;