From 73f0b2af197ed925ea76efd0b2f009843189ba19 Mon Sep 17 00:00:00 2001
From: Mark Renouf <mrenouf@google.com>
Date: Fri, 5 May 2023 12:32:06 -0400
Subject: [PATCH] scroll capture: Recover gracefully when anchor view is lost

When manipulating a RecyclerView, the position of a visible child
view is used as a feedback signal for scroll tracking. If the view
remains detached after scrolling, view operations fail and crash
the application.

Detect this condition and return an empty result. If the RecyclerView
moved during this request, the remaining tiles will be offset by the
same amount. This will manifest as a missing section of content.

Logging has been added to identify and track this bug.

Test: manual repro w/test app; see bug
Bug: 239050369
Change-Id: I5a0a62aaad10ffa7838d7902fd9c5f4f84b52ce6
---
 .../android/internal/view/RecyclerViewCaptureHelper.java   | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/core/java/com/android/internal/view/RecyclerViewCaptureHelper.java b/core/java/com/android/internal/view/RecyclerViewCaptureHelper.java
index 8192ffd102308..f4e9e3064f3d1 100644
--- a/core/java/com/android/internal/view/RecyclerViewCaptureHelper.java
+++ b/core/java/com/android/internal/view/RecyclerViewCaptureHelper.java
@@ -105,6 +105,13 @@ public class RecyclerViewCaptureHelper implements ScrollCaptureViewHelper<ViewGr
         }
 
         if (recyclerView.requestChildRectangleOnScreen(anchor, input, true)) {
+            if (anchor.getParent() == null) {
+                // BUG(b/239050369): Check if the tracked anchor view is still attached.
+                Log.w(TAG, "Bug: anchor view " + anchor + " is detached after scrolling");
+                resultConsumer.accept(result); // empty result
+                return;
+            }
+
             int scrolled = prevAnchorTop - anchor.getTop(); // inverse of movement
             mScrollDelta += scrolled; // view.top-- is equivalent to parent.scrollY++
             result.scrollDelta = mScrollDelta;