From 2a47e6a6ed4d5fdc812e9c1ce3f60b5ff226f31c Mon Sep 17 00:00:00 2001
From: Tony Huang <tonyychuang@google.com>
Date: Mon, 20 Mar 2023 18:47:21 +0800
Subject: [PATCH] Improve exit transition for task close case

We got task vanished callback after its transition animation
finished, and it lead to cause animation not smooth due to the
delay.

When task go to close, we will get a task info changed callback
first and the top activity is null in this callback task info.
We could use it to remove children task info early to reduce
the delay to dismiss split.

Fix: 263320869
Test: manual
Test: pass existing tests
Change-Id: I48486e46e539fe4647fc82a82b530d4637e3a544
---
 .../wm/shell/common/split/SplitLayout.java       |  4 ++++
 .../wm/shell/splitscreen/StageTaskListener.java  | 16 ++++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitLayout.java b/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitLayout.java
index ffc56b6f6106d..b4acd60461829 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitLayout.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/common/split/SplitLayout.java
@@ -727,6 +727,10 @@ public final class SplitLayout implements DisplayInsetsController.OnInsetsChange
         getRefBounds2(mTempRect);
         t.setPosition(leash2, mTempRect.left, mTempRect.top)
                 .setWindowCrop(leash2, mTempRect.width(), mTempRect.height());
+        // Make right or bottom side surface always higher than left or top side to avoid weird
+        // animation when dismiss split. e.g. App surface fling above on decor surface.
+        t.setLayer(leash1, 1);
+        t.setLayer(leash2, 2);
 
         if (mImePositionProcessor.adjustSurfaceLayoutForIme(
                 t, dividerLeash, leash1, leash2, dimLayer1, dimLayer2)) {
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
index a841b7f96d3c5..d6f4d6daaa830 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
@@ -220,12 +220,20 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
                 mCallbacks.onNoLongerSupportMultiWindow();
                 return;
             }
-            mChildrenTaskInfo.put(taskInfo.taskId, taskInfo);
+            if (taskInfo.topActivity == null && mChildrenTaskInfo.contains(taskInfo.taskId)
+                    && mChildrenTaskInfo.get(taskInfo.taskId).topActivity != null) {
+                // If top activity become null, it means the task is about to vanish, we use this
+                // signal to remove it from children list earlier for smooth dismiss transition.
+                mChildrenTaskInfo.remove(taskInfo.taskId);
+                mChildrenLeashes.remove(taskInfo.taskId);
+            } else {
+                mChildrenTaskInfo.put(taskInfo.taskId, taskInfo);
+            }
             mCallbacks.onChildTaskStatusChanged(taskInfo.taskId, true /* present */,
                     taskInfo.isVisible);
-            if (!ENABLE_SHELL_TRANSITIONS) {
-                updateChildTaskSurface(
-                        taskInfo, mChildrenLeashes.get(taskInfo.taskId), false /* firstAppeared */);
+            if (!ENABLE_SHELL_TRANSITIONS && mChildrenLeashes.contains(taskInfo.taskId)) {
+                updateChildTaskSurface(taskInfo, mChildrenLeashes.get(taskInfo.taskId),
+                        false /* firstAppeared */);
             }
         } else {
             throw new IllegalArgumentException(this + "\n Unknown task: " + taskInfo