From e173bbe3bb2e339bfdaa15168d87898b20ec12a5 Mon Sep 17 00:00:00 2001
From: Samuel Susla <samuelsusla@fb.com>
Date: Tue, 18 May 2021 10:01:04 -0700
Subject: [PATCH] Fix on demand mounting in RTL

Summary:
Changelog: [internal]

When calculating on demand views, RTL layout needs to be considered.

Reviewed By: JoshuaGross

Differential Revision: D28510293

fbshipit-source-id: 5e7b08fcc5c55fa1a978024a9bfedda705ce1702
---
 .../ComponentViews/ScrollView/RCTScrollViewComponentView.mm  | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm b/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
index 48816f4c3cf..9ba3054513b 100644
--- a/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
+++ b/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
@@ -622,10 +622,11 @@ static void RCTSendPaperScrollEvent_DEPRECATED(UIScrollView *scrollView, NSInteg
     return;
   }
 
-  CGRect visibleFrame = CGRect{_scrollView.contentOffset, _scrollView.bounds.size};
+  CGRect visibleFrame = [_scrollView convertRect:_scrollView.bounds toView:_containerView];
   visibleFrame = CGRectInset(visibleFrame, -kClippingLeeway, -kClippingLeeway);
 
-  CGFloat scale = 1.0 / _scrollView.zoomScale;
+  // `zoomScale` is negative in RTL. Absolute value is needed.
+  CGFloat scale = 1.0 / std::abs(_scrollView.zoomScale);
   visibleFrame.origin.x *= scale;
   visibleFrame.origin.y *= scale;
   visibleFrame.size.width *= scale;