Render window decoration in WM shell

There are still several things missing in this CL:

1. Still need to wire up freeform resizing. This is done in a separate
   CL.
2. Check if a11y works as intended.
3. Wire up fullscreen and window decorations for freeform displays.
4. Immersive mode work.

Bug: 165794880
Bug: 165794636
Test: Caption shows up.
Change-Id: I7c0e1d55d6c9d03332a58d31ade88aef06a84048

20 files changed, 954 insertions, 76 deletions

diff --git a/libs/WindowManager/Shell/res/color/decor_button_dark_color.xml b/libs/WindowManager/Shell/res/color/decor_button_dark_color.xml
new file mode 100644
index 000000000000..bf325bd84c00
--- /dev/null
+++ b/libs/WindowManager/Shell/res/color/decor_button_dark_color.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<selector xmlns:android="http://schemas.android.com/apk/res/android"
+          xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item app:state_task_focused="true" android:color="#FF000000" />
+    <item android:color="#33000000" />
+</selector>
diff --git a/libs/WindowManager/Shell/res/color/decor_button_light_color.xml b/libs/WindowManager/Shell/res/color/decor_button_light_color.xml
new file mode 100644
index 000000000000..2e48bca7786a
--- /dev/null
+++ b/libs/WindowManager/Shell/res/color/decor_button_light_color.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<selector xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto">
+    <item app:state_task_focused="true" android:color="#FFFFFFFF" />
+    <item android:color="#33FFFFFF" />
+</selector>
\ No newline at end of file
diff --git a/libs/WindowManager/Shell/res/color/decor_caption_title_color.xml b/libs/WindowManager/Shell/res/color/decor_caption_title_color.xml
new file mode 100644
index 000000000000..1ecc13e4da38
--- /dev/null
+++ b/libs/WindowManager/Shell/res/color/decor_caption_title_color.xml
@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<selector xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto">
+     <!-- Fading the to 85% blackness -->
+    <item app:state_task_focused="true" android:color="#D8D8D8" />
+    <!-- Fading the to 95% blackness -->
+    <item android:color="#F2F2F2" />
+</selector>
diff --git a/libs/WindowManager/Shell/res/drawable/decor_caption_title.xml b/libs/WindowManager/Shell/res/drawable/decor_caption_title.xml
new file mode 100644
index 000000000000..8207365a737d
--- /dev/null
+++ b/libs/WindowManager/Shell/res/drawable/decor_caption_title.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<shape android:shape="rectangle"
+       android:tintMode="multiply"
+       android:tint="@color/decor_caption_title_color"
+       xmlns:android="http://schemas.android.com/apk/res/android">
+    <solid android:color="?android:attr/colorPrimary" />
+</shape>
diff --git a/libs/WindowManager/Shell/res/drawable/decor_close_button_dark.xml b/libs/WindowManager/Shell/res/drawable/decor_close_button_dark.xml
new file mode 100644
index 000000000000..f2f1a1d55dee
--- /dev/null
+++ b/libs/WindowManager/Shell/res/drawable/decor_close_button_dark.xml
@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="32.0dp"
+        android:height="32.0dp"
+        android:viewportWidth="32.0"
+        android:viewportHeight="32.0"
+        android:tint="@color/decor_button_dark_color"
+        >
+    <group android:scaleX="0.5"
+            android:scaleY="0.5"
+            android:translateX="8.0"
+            android:translateY="8.0" >
+        <path
+            android:fillColor="@android:color/white"
+            android:pathData="M6.9,4.0l-2.9,2.9 9.1,9.1 -9.1,9.200001 2.9,2.799999 9.1,-9.1 9.1,9.1 2.9,-2.799999 -9.1,-9.200001 9.1,-9.1 -2.9,-2.9 -9.1,9.2z"/>
+    </group>
+</vector>
diff --git a/libs/WindowManager/Shell/res/drawable/decor_maximize_button_dark.xml b/libs/WindowManager/Shell/res/drawable/decor_maximize_button_dark.xml
new file mode 100644
index 000000000000..ab4e29ac97e5
--- /dev/null
+++ b/libs/WindowManager/Shell/res/drawable/decor_maximize_button_dark.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="32.0dp"
+        android:height="32.0dp"
+        android:viewportWidth="32.0"
+        android:viewportHeight="32.0"
+        android:tint="@color/decor_button_dark_color">
+    <group android:scaleX="0.5"
+            android:scaleY="0.5"
+            android:translateX="8.0"
+            android:translateY="8.0" >
+        <path
+            android:fillColor="@android:color/white"
+            android:pathData="M2.0,4.0l0.0,16.0l28.0,0.0L30.0,4.0L2.0,4.0zM26.0,16.0L6.0,16.0L6.0,8.0l20.0,0.0L26.0,16.0z"/>
+        <path
+            android:fillColor="@android:color/white"
+            android:pathData="M2.0,24.0l28.0,0.0l0.0,4.0l-28.0,0.0z"/>
+    </group>
+</vector>
+
+
diff --git a/libs/WindowManager/Shell/res/layout/caption_window_decoration.xml b/libs/WindowManager/Shell/res/layout/caption_window_decoration.xml
new file mode 100644
index 000000000000..a112f1933dd1
--- /dev/null
+++ b/libs/WindowManager/Shell/res/layout/caption_window_decoration.xml
@@ -0,0 +1,45 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2022 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<com.android.wm.shell.windowdecor.WindowDecorLinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/caption"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:gravity="end"
+    android:background="@drawable/decor_caption_title">
+    <Button
+        android:id="@+id/maximize_window"
+        android:layout_width="32dp"
+        android:layout_height="32dp"
+        android:layout_margin="5dp"
+        android:padding="4dp"
+        android:layout_gravity="center_vertical|end"
+        android:contentDescription="@string/maximize_button_text"
+        android:background="@drawable/decor_maximize_button_dark"
+        android:duplicateParentState="true"/>
+    <Button
+        android:id="@+id/close_window"
+        android:layout_width="32dp"
+        android:layout_height="32dp"
+        android:layout_margin="5dp"
+        android:padding="4dp"
+        android:layout_gravity="center_vertical|end"
+        android:contentDescription="@string/close_button_text"
+        android:background="@drawable/decor_close_button_dark"
+        android:duplicateParentState="true"/>
+</com.android.wm.shell.windowdecor.WindowDecorLinearLayout>
+
diff --git a/libs/WindowManager/Shell/res/values/attrs.xml b/libs/WindowManager/Shell/res/values/attrs.xml
index 4aaeef8afcb0..2aad4c1c1805 100644
--- a/libs/WindowManager/Shell/res/values/attrs.xml
+++ b/libs/WindowManager/Shell/res/values/attrs.xml
@@ -19,4 +19,8 @@
         <attr name="icon" format="reference" />
         <attr name="text" format="string" />
     </declare-styleable>
+
+    <declare-styleable name="MessageState">
+        <attr name="state_task_focused" format="boolean"/>
+    </declare-styleable>
 </resources>
diff --git a/libs/WindowManager/Shell/res/values/strings.xml b/libs/WindowManager/Shell/res/values/strings.xml
index a24311fb1f21..b2f09895d7d8 100644
--- a/libs/WindowManager/Shell/res/values/strings.xml
+++ b/libs/WindowManager/Shell/res/values/strings.xml
@@ -186,4 +186,12 @@
     <!-- Button text for dismissing the letterbox education dialog. [CHAR LIMIT=20] -->
     <string name="letterbox_education_got_it">Got it</string>
 
+    <!-- Accessibility description of the letterbox education toast expand to dialog button. [CHAR LIMIT=NONE] -->
+    <string name="letterbox_education_expand_button_description">Expand for more information.</string>
+
+    <!-- Freeform window caption strings -->
+    <!-- Accessibility text for the maximize window button [CHAR LIMIT=NONE] -->
+    <string name="maximize_button_text">Maximize</string>
+    <!-- Accessibility text for the close window button [CHAR LIMIT=NONE] -->
+    <string name="close_button_text">Close</string>
 </resources>
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/ShellInitImpl.java b/libs/WindowManager/Shell/src/com/android/wm/shell/ShellInitImpl.java
index f6a3e7fb54d9..bebafb9dd39a 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/ShellInitImpl.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/ShellInitImpl.java
@@ -57,7 +57,7 @@ public class ShellInitImpl {
     private final FullscreenTaskListener mFullscreenTaskListener;
     private final Optional<FullscreenUnfoldController> mFullscreenUnfoldController;
     private final Optional<UnfoldTransitionHandler> mUnfoldTransitionHandler;
-    private final Optional<FreeformTaskListener> mFreeformTaskListenerOptional;
+    private final Optional<FreeformTaskListener<?>> mFreeformTaskListenerOptional;
     private final ShellExecutor mMainExecutor;
     private final Transitions mTransitions;
     private final StartingWindowController mStartingWindow;
@@ -78,7 +78,7 @@ public class ShellInitImpl {
             FullscreenTaskListener fullscreenTaskListener,
             Optional<FullscreenUnfoldController> fullscreenUnfoldTransitionController,
             Optional<UnfoldTransitionHandler> unfoldTransitionHandler,
-            Optional<FreeformTaskListener> freeformTaskListenerOptional,
+            Optional<FreeformTaskListener<?>> freeformTaskListenerOptional,
             Optional<RecentTasksController> recentTasks,
             Transitions transitions,
             StartingWindowController startingWindow,
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellBaseModule.java b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellBaseModule.java
index 1d10bbe37438..12bff8d4a360 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellBaseModule.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellBaseModule.java
@@ -347,12 +347,12 @@ public abstract class WMShellBaseModule {
     // Workaround for dynamic overriding with a default implementation, see {@link DynamicOverride}
     @BindsOptionalOf
     @DynamicOverride
-    abstract FreeformTaskListener optionalFreeformTaskListener();
+    abstract FreeformTaskListener<?> optionalFreeformTaskListener();
 
     @WMSingleton
     @Provides
-    static Optional<FreeformTaskListener> provideFreeformTaskListener(
-            @DynamicOverride Optional<FreeformTaskListener> freeformTaskListener,
+    static Optional<FreeformTaskListener<?>> provideFreeformTaskListener(
+            @DynamicOverride Optional<FreeformTaskListener<?>> freeformTaskListener,
             Context context) {
         if (FreeformTaskListener.isFreeformEnabled(context)) {
             return freeformTaskListener;
@@ -642,7 +642,7 @@ public abstract class WMShellBaseModule {
             FullscreenTaskListener fullscreenTaskListener,
             Optional<FullscreenUnfoldController> appUnfoldTransitionController,
             Optional<UnfoldTransitionHandler> unfoldTransitionHandler,
-            Optional<FreeformTaskListener> freeformTaskListener,
+            Optional<FreeformTaskListener<?>> freeformTaskListener,
             Optional<RecentTasksController> recentTasksOptional,
             Transitions transitions,
             StartingWindowController startingWindow,
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
index 47c9214bcae9..a4d1ce18f32b 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java
@@ -74,6 +74,8 @@ import com.android.wm.shell.unfold.ShellUnfoldProgressProvider;
 import com.android.wm.shell.unfold.UnfoldBackgroundController;
 import com.android.wm.shell.unfold.UnfoldTransitionHandler;
 import com.android.wm.shell.unfold.animation.FullscreenUnfoldTaskAnimator;
+import com.android.wm.shell.windowdecor.CaptionWindowDecorViewModel;
+import com.android.wm.shell.windowdecor.WindowDecorViewModel;
 
 import java.util.Optional;
 
@@ -128,15 +130,34 @@ public class WMShellModule {
     }
 
     //
+    // Window decoration
+    //
+
+    @WMSingleton
+    @Provides
+    static WindowDecorViewModel<?> provideWindowDecorViewModel(
+            Context context,
+            ShellTaskOrganizer taskOrganizer,
+            DisplayController displayController,
+            SyncTransactionQueue syncQueue) {
+        return new CaptionWindowDecorViewModel(
+                        context,
+                        taskOrganizer,
+                        displayController,
+                        syncQueue);
+    }
+
+    //
     // Freeform
     //
 
     @WMSingleton
     @Provides
     @DynamicOverride
-    static FreeformTaskListener provideFreeformTaskListener(
+    static FreeformTaskListener<?> provideFreeformTaskListener(
+            WindowDecorViewModel<?> windowDecorViewModel,
             SyncTransactionQueue syncQueue) {
-        return new FreeformTaskListener(syncQueue);
+        return new FreeformTaskListener<>(windowDecorViewModel, syncQueue);
     }
 
     //
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/freeform/FreeformTaskListener.java b/libs/WindowManager/Shell/src/com/android/wm/shell/freeform/FreeformTaskListener.java
index fef9be36a35f..fb26cb64f0e7 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/freeform/FreeformTaskListener.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/freeform/FreeformTaskListener.java
@@ -21,8 +21,6 @@ import static android.provider.Settings.Global.DEVELOPMENT_ENABLE_FREEFORM_WINDO
 
 import android.app.ActivityManager.RunningTaskInfo;
 import android.content.Context;
-import android.graphics.Point;
-import android.graphics.Rect;
 import android.provider.Settings;
 import android.util.Slog;
 import android.util.SparseArray;
@@ -32,26 +30,35 @@ import com.android.internal.protolog.common.ProtoLog;
 import com.android.wm.shell.ShellTaskOrganizer;
 import com.android.wm.shell.common.SyncTransactionQueue;
 import com.android.wm.shell.protolog.ShellProtoLogGroup;
+import com.android.wm.shell.windowdecor.WindowDecorViewModel;
 
 import java.io.PrintWriter;
 
 /**
  * {@link ShellTaskOrganizer.TaskListener} for {@link
  * ShellTaskOrganizer#TASK_LISTENER_TYPE_FREEFORM}.
+ *
+ * @param <T> the type of window decoration instance
  */
-public class FreeformTaskListener implements ShellTaskOrganizer.TaskListener {
+public class FreeformTaskListener<T extends AutoCloseable>
+        implements ShellTaskOrganizer.TaskListener {
     private static final String TAG = "FreeformTaskListener";
 
+    private final WindowDecorViewModel<T> mWindowDecorationViewModel;
     private final SyncTransactionQueue mSyncQueue;
 
-    private final SparseArray<State> mTasks = new SparseArray<>();
+    private final SparseArray<State<T>> mTasks = new SparseArray<>();
 
-    private static class State {
+    private static class State<T extends AutoCloseable> {
         RunningTaskInfo mTaskInfo;
         SurfaceControl mLeash;
+        T mWindowDecoration;
     }
 
-    public FreeformTaskListener(SyncTransactionQueue syncQueue) {
+    public FreeformTaskListener(
+            WindowDecorViewModel<T> windowDecorationViewModel,
+            SyncTransactionQueue syncQueue) {
+        mWindowDecorationViewModel = windowDecorationViewModel;
         mSyncQueue = syncQueue;
     }
 
@@ -62,23 +69,17 @@ public class FreeformTaskListener implements ShellTaskOrganizer.TaskListener {
         }
         ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TASK_ORG, "Freeform Task Appeared: #%d",
                 taskInfo.taskId);
-        final State state = new State();
+        final State<T> state = new State<>();
         state.mTaskInfo = taskInfo;
         state.mLeash = leash;
+        state.mWindowDecoration =
+                mWindowDecorationViewModel.createWindowDecoration(taskInfo, leash);
         mTasks.put(taskInfo.taskId, state);
-
-        final Rect taskBounds = taskInfo.configuration.windowConfiguration.getBounds();
-        mSyncQueue.runInSync(t -> {
-            Point taskPosition = taskInfo.positionInParent;
-            t.setPosition(leash, taskPosition.x, taskPosition.y)
-                    .setWindowCrop(leash, taskBounds.width(), taskBounds.height())
-                    .show(leash);
-        });
     }
 
     @Override
     public void onTaskVanished(RunningTaskInfo taskInfo) {
-        State state = mTasks.get(taskInfo.taskId);
+        State<T> state = mTasks.get(taskInfo.taskId);
         if (state == null) {
             Slog.e(TAG, "Task already vanished: #" + taskInfo.taskId);
             return;
@@ -86,11 +87,17 @@ public class FreeformTaskListener implements ShellTaskOrganizer.TaskListener {
         ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TASK_ORG, "Freeform Task Vanished: #%d",
                 taskInfo.taskId);
         mTasks.remove(taskInfo.taskId);
+
+        try {
+            state.mWindowDecoration.close();
+        } catch (Exception e) {
+            Slog.e(TAG, "Failed to release window decoration.", e);
+        }
     }
 
     @Override
     public void onTaskInfoChanged(RunningTaskInfo taskInfo) {
-        State state = mTasks.get(taskInfo.taskId);
+        State<T> state = mTasks.get(taskInfo.taskId);
         if (state == null) {
             throw new RuntimeException(
                     "Task info changed before appearing: #" + taskInfo.taskId);
@@ -98,15 +105,9 @@ public class FreeformTaskListener implements ShellTaskOrganizer.TaskListener {
         ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TASK_ORG, "Freeform Task Info Changed: #%d",
                 taskInfo.taskId);
         state.mTaskInfo = taskInfo;
-
-        final Rect taskBounds = taskInfo.configuration.windowConfiguration.getBounds();
-        final SurfaceControl leash = state.mLeash;
-        mSyncQueue.runInSync(t -> {
-            Point taskPosition = taskInfo.positionInParent;
-            t.setPosition(leash, taskPosition.x, taskPosition.y)
-                    .setWindowCrop(leash, taskBounds.width(), taskBounds.height())
-                    .show(leash);
-        });
+        mWindowDecorationViewModel.onTaskInfoChanged(state.mTaskInfo, state.mWindowDecoration);
+        ProtoLog.v(ShellProtoLogGroup.WM_SHELL_TASK_ORG, "Freeform Task Info Changed: #%d",
+                taskInfo.taskId);
     }
 
     @Override
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
new file mode 100644
index 000000000000..d678f031698e
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor;
+
+import static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
+import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
+import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
+
+import android.app.ActivityManager;
+import android.app.ActivityManager.RunningTaskInfo;
+import android.app.ActivityTaskManager;
+import android.content.Context;
+import android.view.MotionEvent;
+import android.view.SurfaceControl;
+import android.view.View;
+import android.window.WindowContainerToken;
+import android.window.WindowContainerTransaction;
+
+import com.android.wm.shell.R;
+import com.android.wm.shell.ShellTaskOrganizer;
+import com.android.wm.shell.common.DisplayController;
+import com.android.wm.shell.common.SyncTransactionQueue;
+
+/**
+ * View model for the window decoration with a caption and shadows. Works with
+ * {@link CaptionWindowDecoration}.
+ */
+public class CaptionWindowDecorViewModel implements WindowDecorViewModel<CaptionWindowDecoration> {
+    private final ActivityTaskManager mActivityTaskManager;
+    private final ShellTaskOrganizer mTaskOrganizer;
+    private final Context mContext;
+    private final DisplayController mDisplayController;
+    private final SyncTransactionQueue mSyncQueue;
+
+    public CaptionWindowDecorViewModel(
+            Context context,
+            ShellTaskOrganizer taskOrganizer,
+            DisplayController displayController,
+            SyncTransactionQueue syncQueue) {
+        mContext = context;
+        mActivityTaskManager = mContext.getSystemService(ActivityTaskManager.class);
+        mTaskOrganizer = taskOrganizer;
+        mDisplayController = displayController;
+        mSyncQueue = syncQueue;
+    }
+
+    @Override
+    public CaptionWindowDecoration createWindowDecoration(
+            ActivityManager.RunningTaskInfo taskInfo, SurfaceControl taskSurface) {
+        final CaptionWindowDecoration windowDecoration = new CaptionWindowDecoration(
+                mContext,
+                mDisplayController,
+                mTaskOrganizer,
+                taskInfo,
+                taskSurface,
+                mSyncQueue);
+        CaptionTouchEventListener touchEventListener = new CaptionTouchEventListener(taskInfo);
+        windowDecoration.setCaptionListeners(touchEventListener, touchEventListener);
+        onTaskInfoChanged(taskInfo, windowDecoration);
+        return windowDecoration;
+    }
+
+    @Override
+    public void onTaskInfoChanged(RunningTaskInfo taskInfo, CaptionWindowDecoration decoration) {
+        decoration.relayout(taskInfo);
+
+        int statusBarColor = taskInfo.taskDescription.getStatusBarColor();
+        decoration.setCaptionColor(statusBarColor);
+    }
+
+    private class CaptionTouchEventListener implements
+            View.OnClickListener, View.OnTouchListener {
+
+        private final int mTaskId;
+        private final WindowContainerToken mTaskToken;
+
+        private CaptionTouchEventListener(RunningTaskInfo taskInfo) {
+            mTaskId = taskInfo.taskId;
+            mTaskToken = taskInfo.token;
+        }
+
+        @Override
+        public void onClick(View v) {
+            int id = v.getId();
+            if (id == R.id.close_window) {
+                mActivityTaskManager.removeTask(mTaskId);
+            } else if (id == R.id.maximize_window) {
+                WindowContainerTransaction wct = new WindowContainerTransaction();
+                RunningTaskInfo taskInfo = mTaskOrganizer.getRunningTaskInfo(mTaskId);
+                int targetWindowingMode = taskInfo.getWindowingMode() != WINDOWING_MODE_FULLSCREEN
+                        ? WINDOWING_MODE_FULLSCREEN : WINDOWING_MODE_FREEFORM;
+                int displayWindowingMode =
+                        taskInfo.configuration.windowConfiguration.getDisplayWindowingMode();
+                wct.setWindowingMode(mTaskToken,
+                        targetWindowingMode == displayWindowingMode
+                            ? WINDOWING_MODE_UNDEFINED : targetWindowingMode);
+                if (targetWindowingMode == WINDOWING_MODE_FULLSCREEN) {
+                    wct.setBounds(mTaskToken, null);
+                }
+                mSyncQueue.queue(wct);
+            }
+        }
+
+        @Override
+        public boolean onTouch(View v, MotionEvent e) {
+            if (v.getId() != R.id.caption) {
+                return false;
+            }
+            if (e.getAction() != MotionEvent.ACTION_DOWN) {
+                return false;
+            }
+            RunningTaskInfo taskInfo = mTaskOrganizer.getRunningTaskInfo(mTaskId);
+            if (taskInfo.isFocused) {
+                return false;
+            }
+            WindowContainerTransaction wct = new WindowContainerTransaction();
+            wct.reorder(mTaskToken, true /* onTop */);
+            mSyncQueue.queue(wct);
+            return true;
+        }
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
new file mode 100644
index 000000000000..569be23b9f52
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecoration.java
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor;
+
+import android.app.ActivityManager;
+import android.content.Context;
+import android.content.res.ColorStateList;
+import android.graphics.Color;
+import android.graphics.Rect;
+import android.graphics.drawable.GradientDrawable;
+import android.graphics.drawable.VectorDrawable;
+import android.view.SurfaceControl;
+import android.view.View;
+import android.window.WindowContainerTransaction;
+
+import com.android.wm.shell.R;
+import com.android.wm.shell.ShellTaskOrganizer;
+import com.android.wm.shell.common.DisplayController;
+import com.android.wm.shell.common.SyncTransactionQueue;
+
+/**
+ * Defines visuals and behaviors of a window decoration of a caption bar and shadows. It works with
+ * {@link CaptionWindowDecorViewModel}. The caption bar contains maximize and close buttons.
+ *
+ * {@link CaptionWindowDecorViewModel} can change the color of the caption bar based on the foremost
+ * app's request through {@link #setCaptionColor(int)}, in which it changes the foreground color of
+ * caption buttons according to the luminance of the background.
+ *
+ * The shadow's thickness is 20dp when the window is in focus and 5dp when the window isn't.
+ */
+public class CaptionWindowDecoration extends WindowDecoration<WindowDecorLinearLayout> {
+    // The thickness of shadows of a window that has focus in DIP.
+    private static final int DECOR_SHADOW_FOCUSED_THICKNESS_IN_DIP = 20;
+    // The thickness of shadows of a window that doesn't have focus in DIP.
+    private static final int DECOR_SHADOW_UNFOCUSED_THICKNESS_IN_DIP = 5;
+
+    private static final int DECOR_CAPTION_HEIGHT_IN_DIP = 42;
+    private static final Rect EMPTY_OUTSET = new Rect();
+
+    private final SyncTransactionQueue mSyncQueue;
+
+    private View.OnClickListener mOnCaptionButtonClickListener;
+    private View.OnTouchListener mOnCaptionTouchListener;
+
+    private final WindowDecoration.RelayoutResult<WindowDecorLinearLayout> mResult =
+            new WindowDecoration.RelayoutResult<>();
+
+    CaptionWindowDecoration(
+            Context context,
+            DisplayController displayController,
+            ShellTaskOrganizer taskOrganizer,
+            ActivityManager.RunningTaskInfo taskInfo,
+            SurfaceControl taskSurface,
+            SyncTransactionQueue syncQueue) {
+        super(context, displayController, taskOrganizer, taskInfo, taskSurface);
+
+        mSyncQueue = syncQueue;
+    }
+
+    void setCaptionListeners(
+            View.OnClickListener onCaptionButtonClickListener,
+            View.OnTouchListener onCaptionTouchListener) {
+        mOnCaptionButtonClickListener = onCaptionButtonClickListener;
+        mOnCaptionTouchListener = onCaptionTouchListener;
+    }
+
+    void relayout(ActivityManager.RunningTaskInfo taskInfo) {
+        final int shadowRadiusDp = taskInfo.isFocused
+                ? DECOR_SHADOW_FOCUSED_THICKNESS_IN_DIP : DECOR_SHADOW_UNFOCUSED_THICKNESS_IN_DIP;
+
+        WindowDecorLinearLayout oldRootView = mResult.mRootView;
+        final SurfaceControl.Transaction t = new SurfaceControl.Transaction();
+        final WindowContainerTransaction wct = new WindowContainerTransaction();
+        relayout(taskInfo, R.layout.caption_window_decoration, oldRootView,
+                DECOR_CAPTION_HEIGHT_IN_DIP, EMPTY_OUTSET, shadowRadiusDp, t, wct, mResult);
+        taskInfo = null; // Clear it just in case we use it accidentally
+
+        mSyncQueue.runInSync(transaction -> {
+            transaction.merge(t);
+            t.close();
+
+            mTaskOrganizer.applyTransaction(wct);
+        });
+
+        if (mResult.mRootView == null) {
+            return;
+        }
+        if (oldRootView != mResult.mRootView) {
+            setupRootView();
+        }
+    }
+
+    /**
+     * Sets up listeners when a new root view is created.
+     */
+    private void setupRootView() {
+        View caption = mResult.mRootView.findViewById(R.id.caption);
+
+        caption.setOnTouchListener(mOnCaptionTouchListener);
+        View maximize = caption.findViewById(R.id.maximize_window);
+        maximize.setOnClickListener(mOnCaptionButtonClickListener);
+        View close = caption.findViewById(R.id.close_window);
+        close.setOnClickListener(mOnCaptionButtonClickListener);
+    }
+
+    void setCaptionColor(int captionColor) {
+        if (mResult.mRootView == null) {
+            return;
+        }
+
+        View caption = mResult.mRootView.findViewById(R.id.caption);
+        GradientDrawable captionDrawable = (GradientDrawable) caption.getBackground();
+        captionDrawable.setColor(captionColor);
+
+        int buttonTintColorRes =
+                Color.valueOf(captionColor).luminance() < 0.5
+                        ? R.color.decor_button_light_color
+                        : R.color.decor_button_dark_color;
+        ColorStateList buttonTintColor =
+                caption.getResources().getColorStateList(buttonTintColorRes, null /* theme */);
+        View maximize = caption.findViewById(R.id.maximize_window);
+        VectorDrawable maximizeBackground = (VectorDrawable) maximize.getBackground();
+        maximizeBackground.setTintList(buttonTintColor);
+
+        View close = caption.findViewById(R.id.close_window);
+        VectorDrawable closeBackground = (VectorDrawable) close.getBackground();
+        closeBackground.setTintList(buttonTintColor);
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskFocusStateConsumer.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskFocusStateConsumer.java
new file mode 100644
index 000000000000..1c61802bbd5c
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/TaskFocusStateConsumer.java
@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor;
+
+interface TaskFocusStateConsumer {
+    void setTaskFocusState(boolean focused);
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorLinearLayout.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorLinearLayout.java
new file mode 100644
index 000000000000..6d8001a2f92b
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorLinearLayout.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.widget.LinearLayout;
+
+import androidx.annotation.Nullable;
+
+import com.android.wm.shell.R;
+
+/**
+ * A {@link LinearLayout} that takes an additional task focused drawable state. The new state is
+ * used to select the correct background color for views in the window decoration.
+ */
+public class WindowDecorLinearLayout extends LinearLayout implements TaskFocusStateConsumer {
+    private static final int[] TASK_FOCUSED_STATE = { R.attr.state_task_focused };
+
+    private boolean mIsTaskFocused;
+
+    public WindowDecorLinearLayout(Context context) {
+        super(context);
+    }
+
+    public WindowDecorLinearLayout(Context context,
+            @Nullable AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public WindowDecorLinearLayout(Context context, @Nullable AttributeSet attrs,
+            int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+    }
+
+    public WindowDecorLinearLayout(Context context, AttributeSet attrs, int defStyleAttr,
+            int defStyleRes) {
+        super(context, attrs, defStyleAttr, defStyleRes);
+    }
+
+    @Override
+    public void setTaskFocusState(boolean focused) {
+        mIsTaskFocused = focused;
+
+        refreshDrawableState();
+    }
+
+    @Override
+    protected int[] onCreateDrawableState(int extraSpace) {
+        if (!mIsTaskFocused) {
+            return super.onCreateDrawableState(extraSpace);
+        }
+
+        final int[] states = super.onCreateDrawableState(extraSpace + 1);
+        mergeDrawableStates(states, TASK_FOCUSED_STATE);
+        return states;
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorViewModel.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorViewModel.java
new file mode 100644
index 000000000000..6f9ceff722ac
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorViewModel.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor;
+
+import android.app.ActivityManager;
+import android.view.SurfaceControl;
+
+/**
+ * The interface used by some {@link com.android.wm.shell.ShellTaskOrganizer.TaskListener} to help
+ * customize {@link WindowDecoration}. Its implementations are responsible to interpret user's
+ * interactions with UI widgets in window decorations and send corresponding requests to system
+ * servers.
+ *
+ * @param <T> The actual decoration type
+ */
+public interface WindowDecorViewModel<T extends AutoCloseable> {
+
+    /**
+     * Creates a window decoration for the given task.
+     *
+     * @param taskInfo the initial task info of the task
+     * @param taskSurface the surface of the task
+     * @return the window decoration object
+     */
+    T createWindowDecoration(ActivityManager.RunningTaskInfo taskInfo, SurfaceControl taskSurface);
+
+    /**
+     * Notifies a task info update on the given task, with the window decoration created previously
+     * for this task by {@link #createWindowDecoration}.
+     *
+     * @param taskInfo the new task info of the task
+     * @param windowDecoration the window decoration created for the task
+     */
+    void onTaskInfoChanged(ActivityManager.RunningTaskInfo taskInfo, T windowDecoration);
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
new file mode 100644
index 000000000000..00ecdf481343
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecoration.java
@@ -0,0 +1,265 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.wm.shell.windowdecor;
+
+import android.app.ActivityManager.RunningTaskInfo;
+import android.content.Context;
+import android.content.res.Configuration;
+import android.graphics.Color;
+import android.graphics.PixelFormat;
+import android.graphics.Point;
+import android.graphics.Rect;
+import android.util.DisplayMetrics;
+import android.view.Display;
+import android.view.InsetsState;
+import android.view.LayoutInflater;
+import android.view.SurfaceControl;
+import android.view.SurfaceControlViewHost;
+import android.view.View;
+import android.view.WindowManager;
+import android.view.WindowlessWindowManager;
+import android.window.WindowContainerTransaction;
+
+import com.android.wm.shell.ShellTaskOrganizer;
+import com.android.wm.shell.common.DisplayController;
+
+/**
+ * Manages a container surface and a windowless window to show window decoration. Responsible to
+ * update window decoration window state and layout parameters on task info changes and so that
+ * window decoration is in correct state and bounds.
+ *
+ * The container surface is a child of the task display area in the same display, so that window
+ * decorations can be drawn out of the task bounds and receive input events from out of the task
+ * bounds to support drag resizing.
+ *
+ * The windowless window that hosts window decoration is positioned in front of all activities, to
+ * allow the foreground activity to draw its own background behind window decorations, such as
+ * the window captions.
+ *
+ * @param <T> The type of the root view
+ */
+public class WindowDecoration<T extends View & TaskFocusStateConsumer> implements AutoCloseable {
+    private static final int[] CAPTION_INSETS_TYPES = { InsetsState.ITYPE_CAPTION_BAR };
+
+    /**
+     * System-wide context. Only used to create context with overridden configurations.
+     */
+    final Context mContext;
+    final DisplayController mDisplayController;
+    final ShellTaskOrganizer mTaskOrganizer;
+
+    RunningTaskInfo mTaskInfo;
+    final SurfaceControl mTaskSurface;
+
+    Display mDisplay;
+    Context mDecorWindowContext;
+    SurfaceControl mDecorationContainerSurface;
+    SurfaceControl mTaskBackgroundSurface;
+
+    private CaptionWindowManager mCaptionWindowManager;
+    private SurfaceControlViewHost mViewHost;
+
+    private final Rect mCaptionInsetsRect = new Rect();
+    private final Rect mTaskSurfaceCrop = new Rect();
+    private final float[] mTmpColor = new float[3];
+
+    WindowDecoration(
+            Context context,
+            DisplayController displayController,
+            ShellTaskOrganizer taskOrganizer,
+            RunningTaskInfo taskInfo,
+            SurfaceControl taskSurface) {
+        mContext = context;
+        mDisplayController = displayController;
+        mTaskOrganizer = taskOrganizer;
+        mTaskInfo = taskInfo;
+        mTaskSurface = taskSurface;
+
+        mDisplay = mDisplayController.getDisplay(mTaskInfo.displayId);
+        mDecorWindowContext = mContext.createConfigurationContext(mTaskInfo.getConfiguration());
+
+        // Put caption under task surface because ViewRootImpl sets the destination frame of
+        // windowless window layers and BLASTBufferQueue#update() doesn't support offset.
+        mCaptionWindowManager =
+                new CaptionWindowManager(mTaskInfo.getConfiguration(), mTaskSurface);
+    }
+
+    void relayout(RunningTaskInfo taskInfo, int layoutResId, T rootView, float captionHeightDp,
+            Rect outsetsDp, float shadowRadiusDp, SurfaceControl.Transaction t,
+            WindowContainerTransaction wct, RelayoutResult<T> outResult) {
+        outResult.reset();
+
+        final Configuration oldTaskConfig = mTaskInfo.getConfiguration();
+        if (taskInfo != null) {
+            mTaskInfo = taskInfo;
+        }
+
+        if (!mTaskInfo.isVisible) {
+            close();
+            t.hide(mTaskSurface);
+            return;
+        }
+
+        if (rootView == null && layoutResId == 0) {
+            throw new IllegalArgumentException("layoutResId and rootView can't both be invalid.");
+        }
+
+        outResult.mRootView = rootView;
+        rootView = null; // Clear it just in case we use it accidentally
+        final Configuration taskConfig = mTaskInfo.getConfiguration();
+        if (oldTaskConfig.densityDpi != taskConfig.densityDpi
+                || mDisplay.getDisplayId() != mTaskInfo.displayId) {
+            close();
+
+            mDisplay = mDisplayController.getDisplay(mTaskInfo.displayId);
+            mDecorWindowContext = mContext.createConfigurationContext(taskConfig);
+            if (layoutResId != 0) {
+                outResult.mRootView =
+                        (T) LayoutInflater.from(mDecorWindowContext).inflate(layoutResId, null);
+            }
+        }
+
+        if (outResult.mRootView == null) {
+            outResult.mRootView =
+                    (T) LayoutInflater.from(mDecorWindowContext).inflate(layoutResId, null);
+        }
+
+        // DecorationContainerSurface
+        if (mDecorationContainerSurface == null) {
+            final SurfaceControl.Builder builder = new SurfaceControl.Builder();
+            mDecorationContainerSurface = builder
+                    .setName("Decor container of Task=" + mTaskInfo.taskId)
+                    .setContainerLayer()
+                    .setParent(mTaskSurface)
+                    .build();
+
+            t.setTrustedOverlay(mDecorationContainerSurface, true);
+        }
+
+        final Rect taskBounds = taskConfig.windowConfiguration.getBounds();
+        outResult.mDensity = taskConfig.densityDpi * DisplayMetrics.DENSITY_DEFAULT_SCALE;
+        final int decorContainerOffsetX = -(int) (outsetsDp.left * outResult.mDensity);
+        final int decorContainerOffsetY = -(int) (outsetsDp.top * outResult.mDensity);
+        outResult.mWidth = taskBounds.width()
+                + (int) (outsetsDp.right * outResult.mDensity)
+                - decorContainerOffsetX;
+        outResult.mHeight = taskBounds.height()
+                + (int) (outsetsDp.bottom * outResult.mDensity)
+                - decorContainerOffsetY;
+        t.setPosition(mDecorationContainerSurface, decorContainerOffsetX, decorContainerOffsetY)
+                .setWindowCrop(mDecorationContainerSurface, outResult.mWidth, outResult.mHeight)
+                .setLayer(mDecorationContainerSurface, mTaskInfo.numActivities + 1)
+                .show(mDecorationContainerSurface);
+
+        // TaskBackgroundSurface
+        if (mTaskBackgroundSurface == null) {
+            final SurfaceControl.Builder builder = new SurfaceControl.Builder();
+            mTaskBackgroundSurface = builder
+                    .setName("Background of Task=" + mTaskInfo.taskId)
+                    .setEffectLayer()
+                    .setParent(mTaskSurface)
+                    .build();
+        }
+
+        float shadowRadius = outResult.mDensity * shadowRadiusDp;
+        int backgroundColorInt = mTaskInfo.taskDescription.getBackgroundColor();
+        mTmpColor[0] = Color.red(backgroundColorInt);
+        mTmpColor[1] = Color.green(backgroundColorInt);
+        mTmpColor[2] = Color.blue(backgroundColorInt);
+        t.setCrop(mTaskBackgroundSurface, taskBounds)
+                .setShadowRadius(mTaskBackgroundSurface, shadowRadius)
+                .setColor(mTaskBackgroundSurface, mTmpColor);
+
+        // Caption view
+        mCaptionWindowManager.setConfiguration(taskConfig);
+        final int captionHeight = (int) Math.ceil(captionHeightDp * outResult.mDensity);
+        final WindowManager.LayoutParams lp =
+                new WindowManager.LayoutParams(taskBounds.width(), captionHeight,
+                        WindowManager.LayoutParams.TYPE_APPLICATION,
+                        WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE, PixelFormat.TRANSPARENT);
+        lp.setTitle("Caption of Task=" + mTaskInfo.taskId);
+        lp.setTrustedOverlay();
+        if (mViewHost == null) {
+            mViewHost = new SurfaceControlViewHost(mDecorWindowContext, mDisplay,
+                    mCaptionWindowManager, true);
+            mViewHost.setView(outResult.mRootView, lp);
+        } else {
+            mViewHost.relayout(lp);
+        }
+
+        outResult.mRootView.setTaskFocusState(mTaskInfo.isFocused);
+
+        // Caption insets
+        mCaptionInsetsRect.set(taskBounds);
+        mCaptionInsetsRect.bottom = mCaptionInsetsRect.top + captionHeight;
+        wct.addRectInsetsProvider(mTaskInfo.token, mCaptionInsetsRect, CAPTION_INSETS_TYPES);
+
+        // Task surface itself
+        Point taskPosition = mTaskInfo.positionInParent;
+        mTaskSurfaceCrop.set(
+                decorContainerOffsetX,
+                decorContainerOffsetY,
+                outResult.mWidth + decorContainerOffsetX,
+                outResult.mHeight + decorContainerOffsetY);
+        t.setPosition(mTaskSurface, taskPosition.x, taskPosition.y)
+                .setCrop(mTaskSurface, mTaskSurfaceCrop)
+                .show(mTaskSurface);
+    }
+
+    @Override
+    public void close() {
+        if (mViewHost != null) {
+            mViewHost.release();
+            mViewHost = null;
+        }
+
+        if (mDecorationContainerSurface != null) {
+            mDecorationContainerSurface.release();
+            mDecorationContainerSurface = null;
+        }
+
+        if (mTaskBackgroundSurface != null) {
+            mTaskBackgroundSurface.release();
+            mTaskBackgroundSurface = null;
+        }
+    }
+
+    static class RelayoutResult<T extends View & TaskFocusStateConsumer> {
+        int mWidth;
+        int mHeight;
+        float mDensity;
+        T mRootView;
+
+        void reset() {
+            mWidth = 0;
+            mHeight = 0;
+            mDensity = 0;
+            mRootView = null;
+        }
+    }
+
+    private static class CaptionWindowManager extends WindowlessWindowManager {
+        CaptionWindowManager(Configuration config, SurfaceControl rootSurface) {
+            super(config, rootSurface, null /* hostInputToken */);
+        }
+
+        @Override
+        public void setConfiguration(Configuration configuration) {
+            super.setConfiguration(configuration);
+        }
+    }
+}
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index 7c1488b71bf5..fc1b89348c25 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -69,8 +69,6 @@ import static android.view.WindowManager.TRANSIT_TO_BACK;
 import static android.view.WindowManager.TRANSIT_TO_FRONT;
 import static android.window.DisplayAreaOrganizer.FEATURE_UNDEFINED;
 
-import static com.android.internal.policy.DecorView.DECOR_SHADOW_FOCUSED_HEIGHT_IN_DIP;
-import static com.android.internal.policy.DecorView.DECOR_SHADOW_UNFOCUSED_HEIGHT_IN_DIP;
 import static com.android.internal.protolog.ProtoLogGroup.WM_DEBUG_ADD_REMOVE;
 import static com.android.internal.protolog.ProtoLogGroup.WM_DEBUG_BACK_PREVIEW;
 import static com.android.internal.protolog.ProtoLogGroup.WM_DEBUG_LOCKTASK;
@@ -131,7 +129,6 @@ import static com.android.server.wm.WindowContainerChildProto.TASK;
 import static com.android.server.wm.WindowManagerDebugConfig.DEBUG_ROOT_TASK;
 import static com.android.server.wm.WindowManagerDebugConfig.DEBUG_TASK_MOVEMENT;
 import static com.android.server.wm.WindowManagerDebugConfig.TAG_WM;
-import static com.android.server.wm.WindowManagerService.dipToPixel;
 
 import static java.lang.Integer.MAX_VALUE;
 
@@ -3277,7 +3274,6 @@ class Task extends TaskFragment {
         }
 
         final SurfaceControl.Transaction t = getSyncTransaction();
-        updateShadowsRadius(isFocused(), t);
 
         if (mDimmer.updateDims(t, mTmpDimBoundsRect)) {
             scheduleAnimation();
@@ -4249,48 +4245,10 @@ class Task extends TaskFragment {
     }
 
     /**
-     * @return the desired shadow radius in pixels for the current task.
-     */
-    private float getShadowRadius(boolean taskIsFocused) {
-        int elevation = 0;
-
-        // Get elevation for a specific windowing mode.
-        if (inFreeformWindowingMode()) {
-            elevation = taskIsFocused
-                    ? DECOR_SHADOW_FOCUSED_HEIGHT_IN_DIP : DECOR_SHADOW_UNFOCUSED_HEIGHT_IN_DIP;
-        } else {
-            // For all other windowing modes, do not draw a shadow.
-            return 0;
-        }
-
-        // If the task has no visible children, do not draw a shadow.
-        if (!hasVisibleChildren()) {
-            return 0;
-        }
-
-        return dipToPixel(elevation, getDisplayContent().getDisplayMetrics());
-    }
-
-    /**
-     * Update the length of the shadow if needed based on windowing mode and task focus state.
-     */
-    private void updateShadowsRadius(boolean taskIsFocused,
-            SurfaceControl.Transaction pendingTransaction) {
-        if (!isRootTask()) return;
-
-        final float newShadowRadius = getShadowRadius(taskIsFocused);
-        if (mShadowRadius != newShadowRadius) {
-            mShadowRadius = newShadowRadius;
-            pendingTransaction.setShadowRadius(getSurfaceControl(), mShadowRadius);
-        }
-    }
-
-    /**
      * Called on the task when it gained or lost focus.
      * @param hasFocus
      */
     void onAppFocusChanged(boolean hasFocus) {
-        updateShadowsRadius(hasFocus, getSyncTransaction());
         dispatchTaskInfoChangedIfNeeded(false /* force */);
     }