From b8a2a026a59175f175580e35c13ec3abbca895a8 Mon Sep 17 00:00:00 2001
From: Winson Chung <winsonc@google.com>
Date: Mon, 15 Aug 2022 23:44:42 +0000
Subject: [PATCH] Defer adding surface changed callback until view root is
 valid

- It appears there are cases where the view root is not valid (in
  which case schedule() returns false and we don't wait to handle
  the callback) which causes an NPE, but in these cases we don't
  need to add the surface changed callback at all.

Bug: 202776119
Bug: 242347940
Bug: 242897135
Test: Launch an app with sharesheet, swipe up and verify that
      screenshot callbacks

Change-Id: Icc3afc604bd925c5d49c693b7de51755f5a8bd42
---
 quickstep/src/com/android/quickstep/ViewUtils.java | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/quickstep/src/com/android/quickstep/ViewUtils.java b/quickstep/src/com/android/quickstep/ViewUtils.java
index 1bb95b97f9..b1320674e6 100644
--- a/quickstep/src/com/android/quickstep/ViewUtils.java
+++ b/quickstep/src/com/android/quickstep/ViewUtils.java
@@ -53,13 +53,13 @@ public class ViewUtils {
         final Runnable mFinishCallback;
         final BooleanSupplier mCancelled;
         final Handler mHandler;
+        boolean mSurfaceCallbackRegistered = false;
         boolean mFinished;
 
         int mDeferFrameCount = 1;
 
         FrameHandler(View view, Runnable finishCallback, BooleanSupplier cancelled) {
             mViewRoot = view.getViewRootImpl();
-            mViewRoot.addSurfaceChangedCallback(this);
             mFinishCallback = finishCallback;
             mCancelled = cancelled;
             mHandler = new Handler();
@@ -103,6 +103,10 @@ public class ViewUtils {
 
         private boolean schedule() {
             if (mViewRoot != null && mViewRoot.getView() != null) {
+                if (!mSurfaceCallbackRegistered) {
+                    mSurfaceCallbackRegistered = true;
+                    mViewRoot.addSurfaceChangedCallback(this);
+                }
                 mViewRoot.registerRtFrameCallback(this);
                 mViewRoot.getView().invalidate();
                 return true;
@@ -119,7 +123,10 @@ public class ViewUtils {
             if (mFinishCallback != null) {
                 mFinishCallback.run();
             }
-            mViewRoot.removeSurfaceChangedCallback(this);
+            if (mViewRoot != null) {
+                mViewRoot.removeSurfaceChangedCallback(this);
+                mSurfaceCallbackRegistered = false;
+            }
         }
     }
 }