From 8959d0b1398e4dcc94762ae717293c241fb3c064 Mon Sep 17 00:00:00 2001
From: Jerry Chang <chenghsiuchang@google.com>
Date: Mon, 20 Dec 2021 11:09:56 +0000
Subject: [PATCH] Fix back to split pair from overview with shell-transition
 hang.

Prevent it throws index out of bounds exception when entering split pair
from overview panel. And make sure to update split screen state properly
when enter split transition got merged to other transition.

Fix: 210852531
Bug: 206487881
Test: Trigger split screen, swipe up to overview, verified it won't hang
      when select split pair from overview panel.
Change-Id: Ifc5c224b7185224b811e6e2e7fa5d798c99bc6b1
---
 .../shell/splitscreen/StageCoordinator.java   | 21 +++++++++++++++++++
 .../shared/system/RemoteTransitionCompat.java |  6 +-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
index 2385ec90ab232..c87f0bcb469c8 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
@@ -1207,6 +1207,27 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         return out;
     }
 
+    @Override
+    public void onTransitionMerged(@NonNull IBinder transition) {
+        // Once the pending enter transition got merged, make sure to bring divider bar visible and
+        // clear the pending transition from cache to prevent mess-up the following state.
+        if (transition == mSplitTransitions.mPendingEnter) {
+            mSplitLayout.init();
+            setDividerVisibility(true, null /* transaction */);
+            setSplitsVisible(true);
+            mShouldUpdateRecents = true;
+            updateRecentTasksSplitPair();
+
+            if (!mLogger.hasStartedSession()) {
+                mLogger.logEnter(mSplitLayout.getDividerPositionAsFraction(),
+                        getMainStagePosition(), mMainStage.getTopChildTaskUid(),
+                        getSideStagePosition(), mSideStage.getTopChildTaskUid(),
+                        mSplitLayout.isLandscape());
+            }
+            mSplitTransitions.mPendingEnter = null;
+        }
+    }
+
     @Override
     public boolean startAnimation(@NonNull IBinder transition,
             @NonNull TransitionInfo info,
diff --git a/packages/SystemUI/shared/src/com/android/systemui/shared/system/RemoteTransitionCompat.java b/packages/SystemUI/shared/src/com/android/systemui/shared/system/RemoteTransitionCompat.java
index 3cd090e3e0144..2d5080eaaa221 100644
--- a/packages/SystemUI/shared/src/com/android/systemui/shared/system/RemoteTransitionCompat.java
+++ b/packages/SystemUI/shared/src/com/android/systemui/shared/system/RemoteTransitionCompat.java
@@ -246,10 +246,6 @@ public class RemoteTransitionCompat implements Parcelable {
                 if (mPausingTasks.contains(openingTasks.get(i).getContainer())) {
                     ++pauseMatches;
                 }
-                if (openingTasks.get(i).getContainer().equals(mPausingTasks.get(i))) {
-                    // In this case, we are "returning" to an already running app, so just consume
-                    // the merge and do nothing.
-                }
             }
             if (pauseMatches > 0) {
                 if (pauseMatches != mPausingTasks.size()) {
@@ -275,9 +271,9 @@ public class RemoteTransitionCompat implements Parcelable {
                 t.reparent(target.leash.mSurfaceControl, mInfo.getRootLeash());
                 t.setLayer(target.leash.mSurfaceControl, layer);
                 t.hide(target.leash.mSurfaceControl);
-                t.apply();
                 targets[i] = target;
             }
+            t.apply();
             recents.onTasksAppeared(targets);
             return true;
         }