From 8f209acb3f7338448b0b7a26224fc4b2cfb722db Mon Sep 17 00:00:00 2001
From: Fabrizio Cucci <fabriziocucci@meta.com>
Date: Wed, 5 Mar 2025 11:47:52 -0800
Subject: [PATCH] Fix out of sync state in ScrollView after animation

Summary:
It seems that if we update the scroll state when the state wrapper is null we can get into an out of sync state.

I've replicated the issue in HelpCenter and confirmed with a video this seems to be the case (i.e. when gazing on some cards, their corresponding frame is incorrect)

https://www.internalfb.com/intern/px/p/6xWgl

NOTE: I have accidentally stumbled upon this fix but I could really use a review from someone who has more context around the `ReactScrollViewHelper` because this change might have bigger implications I'm not aware of!

    Changelog:
    [Android][Fixed] - Fix occasional syncronization issue in ScrollView when rendering dynamic content with content offset

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Reviewed By: javache

Differential Revision: D70484547

fbshipit-source-id: c314b958eeed4dd96755539f5bbfb8f03e17a525
---
 .../com/facebook/react/views/scroll/ReactScrollViewHelper.kt | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewHelper.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewHelper.kt
index df3d8e98b30..5b3f661c634 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewHelper.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollViewHelper.kt
@@ -315,6 +315,11 @@ public object ReactScrollViewHelper {
     if (ViewUtil.getUIManagerType(scrollView.id) == UIManagerType.DEFAULT) {
       return
     }
+    // NOTE: if the state wrapper is null, we shouldn't even update
+    // the scroll state because there is a chance of going out of sync!
+    if (scrollView.stateWrapper == null) {
+      return
+    }
     val scrollState = scrollView.reactScrollViewScrollState
     // Dedupe events to reduce JNI traffic
     if (scrollState.lastStateUpdateScroll.equals(scrollX, scrollY)) {