From c938c0afbfbd0e5ba8853feb212a976f605f51f0 Mon Sep 17 00:00:00 2001
From: Luna Wei <luwe@fb.com>
Date: Mon, 9 Mar 2020 18:25:18 -0700
Subject: [PATCH] Adjust Layout Animation with pending deletion set

Summary:
Changelog: [Internal]
This solves the problem of viewToAdd indices being invalid if the deletes are asynchronous within the scope of one `manageChildren` call.

Since deletions are performed first, we keep a set of tags being deleted.
During view insertion, we iterate through and filter those tags out of our count.

Reviewed By: JoshuaGross

Differential Revision: D20324643

fbshipit-source-id: 150230428fcd65b8c43cc1f2331e9ce02d31fff9
---
 .../uimanager/NativeViewHierarchyManager.java | 24 ++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java
index 93ccf116e3e..55208453fc7 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/NativeViewHierarchyManager.java
@@ -35,6 +35,8 @@ import com.facebook.react.uimanager.layoutanimation.LayoutAnimationListener;
 import com.facebook.systrace.Systrace;
 import com.facebook.systrace.SystraceMessage;
 import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
 import javax.annotation.concurrent.NotThreadSafe;
 
 /**
@@ -363,6 +365,7 @@ public class NativeViewHierarchyManager {
       @Nullable int[] tagsToDelete) {
     UiThreadUtil.assertOnUiThread();
 
+    final Set<Integer> pendingDeletionTags = new HashSet<>();
     mLayoutAnimator.cancelAnimationsForViewTag(tag);
 
     final ViewGroup viewToManage = (ViewGroup) mTagsToViews.get(tag);
@@ -446,6 +449,7 @@ public class NativeViewHierarchyManager {
         }
 
         if (mLayoutAnimationEnabled && mLayoutAnimator.shouldAnimateLayout(viewToDestroy)) {
+          pendingDeletionTags.add(tagToDelete);
           mLayoutAnimator.deleteView(
               tag,
               viewToDestroy,
@@ -458,6 +462,7 @@ public class NativeViewHierarchyManager {
 
                   viewManager.removeView(viewToManage, viewToDestroy);
                   dropView(viewToDestroy);
+                  pendingDeletionTags.remove(viewToDestroy.getId());
                 }
               });
         } else {
@@ -478,7 +483,24 @@ public class NativeViewHierarchyManager {
                   + constructManageChildrenErrorMessage(
                       viewToManage, viewManager, indicesToRemove, viewsToAdd, tagsToDelete));
         }
-        viewManager.addView(viewToManage, viewToAdd, viewAtIndex.mIndex);
+
+        int normalizedIndex = viewAtIndex.mIndex;
+        if (!pendingDeletionTags.isEmpty()) {
+          normalizedIndex = 0;
+          int counter = 0;
+          while (normalizedIndex < viewToManage.getChildCount()) {
+            if (counter == viewAtIndex.mIndex) {
+              break;
+            }
+            View v = viewToManage.getChildAt(normalizedIndex);
+            if (!pendingDeletionTags.contains(v.getId())) {
+              counter++;
+            }
+            normalizedIndex++;
+          }
+        }
+
+        viewManager.addView(viewToManage, viewToAdd, normalizedIndex);
       }
     }
   }