Add split screen unfold animation

Creates controllers in the Shell that manipulate
SurfaceControl leashes of the current active
split screen surfaces based on the current
unfold transition progress.

Bug: 193795566
Test: manual
Change-Id: Ib80807c632444b2939e9b075fb24fd40cc14648a

15 files changed, 573 insertions, 91 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/fullscreen/FullscreenUnfoldController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/fullscreen/FullscreenUnfoldController.java
index 08ab85cab97b..fc1b704e95ad 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/fullscreen/FullscreenUnfoldController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/fullscreen/FullscreenUnfoldController.java
@@ -16,9 +16,6 @@
 
 package com.android.wm.shell.fullscreen;
 
-import static android.graphics.Color.blue;
-import static android.graphics.Color.green;
-import static android.graphics.Color.red;
 import static android.util.MathUtils.lerp;
 import static android.view.Display.DEFAULT_DISPLAY;
 
@@ -36,12 +33,11 @@ import android.view.InsetsState;
 import android.view.SurfaceControl;
 
 import com.android.internal.policy.ScreenDecorationsUtils;
-import com.android.wm.shell.R;
-import com.android.wm.shell.RootTaskDisplayAreaOrganizer;
 import com.android.wm.shell.common.DisplayInsetsController;
 import com.android.wm.shell.common.DisplayInsetsController.OnInsetsChangedListener;
 import com.android.wm.shell.unfold.ShellUnfoldProgressProvider;
 import com.android.wm.shell.unfold.ShellUnfoldProgressProvider.UnfoldListener;
+import com.android.wm.shell.unfold.UnfoldBackgroundController;
 
 import java.util.concurrent.Executor;
 
@@ -59,21 +55,17 @@ public final class FullscreenUnfoldController implements UnfoldListener,
     private static final float VERTICAL_START_MARGIN = 0.03f;
     private static final float END_SCALE = 1f;
     private static final float START_SCALE = END_SCALE - VERTICAL_START_MARGIN * 2;
-    private static final int BACKGROUND_LAYER_Z_INDEX = -1;
 
-    private final Context mContext;
     private final Executor mExecutor;
     private final ShellUnfoldProgressProvider mProgressProvider;
-    private final RootTaskDisplayAreaOrganizer mRootTaskDisplayAreaOrganizer;
     private final DisplayInsetsController mDisplayInsetsController;
 
     private final SparseArray<AnimationContext> mAnimationContextByTaskId = new SparseArray<>();
+    private final UnfoldBackgroundController mBackgroundController;
 
-    private SurfaceControl mBackgroundLayer;
     private InsetsSource mTaskbarInsetsSource;
 
     private final float mWindowCornerRadiusPx;
-    private final float[] mBackgroundColor;
     private final float mExpandedTaskBarHeight;
 
     private final SurfaceControl.Transaction mTransaction = new SurfaceControl.Transaction();
@@ -81,19 +73,17 @@ public final class FullscreenUnfoldController implements UnfoldListener,
     public FullscreenUnfoldController(
             @NonNull Context context,
             @NonNull Executor executor,
+            @NonNull UnfoldBackgroundController backgroundController,
             @NonNull ShellUnfoldProgressProvider progressProvider,
-            @NonNull RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
             @NonNull DisplayInsetsController displayInsetsController
     ) {
-        mContext = context;
         mExecutor = executor;
-        mRootTaskDisplayAreaOrganizer = rootTaskDisplayAreaOrganizer;
         mProgressProvider = progressProvider;
         mDisplayInsetsController = displayInsetsController;
         mWindowCornerRadiusPx = ScreenDecorationsUtils.getWindowCornerRadius(context);
         mExpandedTaskBarHeight = context.getResources().getDimensionPixelSize(
                 com.android.internal.R.dimen.taskbar_frame_height);
-        mBackgroundColor = getBackgroundColor();
+        mBackgroundController = backgroundController;
     }
 
     /**
@@ -108,7 +98,7 @@ public final class FullscreenUnfoldController implements UnfoldListener,
     public void onStateChangeProgress(float progress) {
         if (mAnimationContextByTaskId.size() == 0) return;
 
-        ensureBackground();
+        mBackgroundController.ensureBackground(mTransaction);
 
         for (int i = mAnimationContextByTaskId.size() - 1; i >= 0; i--) {
             final AnimationContext context = mAnimationContextByTaskId.valueAt(i);
@@ -135,7 +125,7 @@ public final class FullscreenUnfoldController implements UnfoldListener,
             resetSurface(context);
         }
 
-        removeBackground();
+        mBackgroundController.removeBackground(mTransaction);
         mTransaction.apply();
     }
 
@@ -178,7 +168,7 @@ public final class FullscreenUnfoldController implements UnfoldListener,
         }
 
         if (mAnimationContextByTaskId.size() == 0) {
-            removeBackground();
+            mBackgroundController.removeBackground(mTransaction);
         }
 
         mTransaction.apply();
@@ -194,39 +184,6 @@ public final class FullscreenUnfoldController implements UnfoldListener,
                         (float) context.mTaskInfo.positionInParent.y);
     }
 
-    private void ensureBackground() {
-        if (mBackgroundLayer != null) return;
-
-        SurfaceControl.Builder colorLayerBuilder = new SurfaceControl.Builder()
-                .setName("app-unfold-background")
-                .setCallsite("AppUnfoldTransitionController")
-                .setColorLayer();
-        mRootTaskDisplayAreaOrganizer.attachToDisplayArea(DEFAULT_DISPLAY, colorLayerBuilder);
-        mBackgroundLayer = colorLayerBuilder.build();
-
-        mTransaction
-                .setColor(mBackgroundLayer, mBackgroundColor)
-                .show(mBackgroundLayer)
-                .setLayer(mBackgroundLayer, BACKGROUND_LAYER_Z_INDEX);
-    }
-
-    private void removeBackground() {
-        if (mBackgroundLayer == null) return;
-        if (mBackgroundLayer.isValid()) {
-            mTransaction.remove(mBackgroundLayer);
-        }
-        mBackgroundLayer = null;
-    }
-
-    private float[] getBackgroundColor() {
-        int colorInt = mContext.getResources().getColor(R.color.unfold_transition_background);
-        return new float[]{
-                (float) red(colorInt) / 255.0F,
-                (float) green(colorInt) / 255.0F,
-                (float) blue(colorInt) / 255.0F
-        };
-    }
-
     private class AnimationContext {
         final SurfaceControl mLeash;
         final Rect mStartCropRect = new Rect();
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java
index d0998eb57633..7f82ebde77af 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/MainStage.java
@@ -18,6 +18,7 @@ package com.android.wm.shell.splitscreen;
 
 import static android.app.WindowConfiguration.WINDOWING_MODE_MULTI_WINDOW;
 
+import android.annotation.Nullable;
 import android.graphics.Rect;
 import android.view.SurfaceSession;
 import android.window.WindowContainerToken;
@@ -38,8 +39,10 @@ class MainStage extends StageTaskListener {
 
     MainStage(ShellTaskOrganizer taskOrganizer, int displayId,
             StageListenerCallbacks callbacks, SyncTransactionQueue syncQueue,
-            SurfaceSession surfaceSession) {
-        super(taskOrganizer, displayId, callbacks, syncQueue, surfaceSession);
+            SurfaceSession surfaceSession,
+            @Nullable StageTaskUnfoldController stageTaskUnfoldController) {
+        super(taskOrganizer, displayId, callbacks, syncQueue, surfaceSession,
+                stageTaskUnfoldController);
     }
 
     boolean isActive() {
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java
index 0e7ccd3515c4..dc8fb9fbd7a3 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SideStage.java
@@ -46,8 +46,10 @@ class SideStage extends StageTaskListener implements
 
     SideStage(Context context, ShellTaskOrganizer taskOrganizer, int displayId,
             StageListenerCallbacks callbacks, SyncTransactionQueue syncQueue,
-            SurfaceSession surfaceSession) {
-        super(taskOrganizer, displayId, callbacks, syncQueue, surfaceSession);
+            SurfaceSession surfaceSession,
+            @Nullable StageTaskUnfoldController stageTaskUnfoldController) {
+        super(taskOrganizer, displayId, callbacks, syncQueue, surfaceSession,
+                stageTaskUnfoldController);
         mContext = context;
     }
 
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java
index ac68b3b8a6a9..0d5271924375 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java
@@ -68,8 +68,11 @@ import com.android.wm.shell.transition.Transitions;
 
 import java.io.PrintWriter;
 import java.util.Arrays;
+import java.util.Optional;
 import java.util.concurrent.Executor;
 
+import javax.inject.Provider;
+
 /**
  * Class manages split-screen multitasking mode and implements the main interface
  * {@link SplitScreen}.
@@ -91,6 +94,7 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
     private final Transitions mTransitions;
     private final TransactionPool mTransactionPool;
     private final SplitscreenEventLogger mLogger;
+    private final Provider<Optional<StageTaskUnfoldController>> mUnfoldControllerProvider;
 
     private StageCoordinator mStageCoordinator;
 
@@ -99,7 +103,8 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
             RootTaskDisplayAreaOrganizer rootTDAOrganizer,
             ShellExecutor mainExecutor, DisplayImeController displayImeController,
             DisplayInsetsController displayInsetsController,
-            Transitions transitions, TransactionPool transactionPool) {
+            Transitions transitions, TransactionPool transactionPool,
+            Provider<Optional<StageTaskUnfoldController>> unfoldControllerProvider) {
         mTaskOrganizer = shellTaskOrganizer;
         mSyncQueue = syncQueue;
         mContext = context;
@@ -109,6 +114,7 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
         mDisplayInsetsController = displayInsetsController;
         mTransitions = transitions;
         mTransactionPool = transactionPool;
+        mUnfoldControllerProvider = unfoldControllerProvider;
         mLogger = new SplitscreenEventLogger();
     }
 
@@ -131,7 +137,8 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
             // TODO: Multi-display
             mStageCoordinator = new StageCoordinator(mContext, DEFAULT_DISPLAY, mSyncQueue,
                     mRootTDAOrganizer, mTaskOrganizer, mDisplayImeController,
-                    mDisplayInsetsController, mTransitions, mTransactionPool, mLogger);
+                    mDisplayInsetsController, mTransitions, mTransactionPool, mLogger,
+                    mUnfoldControllerProvider);
         }
     }
 
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 d7a6cfff6c6f..c3e9d54ce29f 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
@@ -95,6 +95,9 @@ import com.android.wm.shell.transition.Transitions;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
+
+import javax.inject.Provider;
 
 /**
  * Coordinates the staging (visibility, sizing, ...) of the split-screen {@link MainStage} and
@@ -121,8 +124,10 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
 
     private final MainStage mMainStage;
     private final StageListenerImpl mMainStageListener = new StageListenerImpl();
+    private final StageTaskUnfoldController mMainUnfoldController;
     private final SideStage mSideStage;
     private final StageListenerImpl mSideStageListener = new StageListenerImpl();
+    private final StageTaskUnfoldController mSideUnfoldController;
     @SplitPosition
     private int mSideStagePosition = SPLIT_POSITION_BOTTOM_OR_RIGHT;
 
@@ -179,26 +184,32 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             RootTaskDisplayAreaOrganizer rootTDAOrganizer, ShellTaskOrganizer taskOrganizer,
             DisplayImeController displayImeController,
             DisplayInsetsController displayInsetsController, Transitions transitions,
-            TransactionPool transactionPool, SplitscreenEventLogger logger) {
+            TransactionPool transactionPool, SplitscreenEventLogger logger,
+            Provider<Optional<StageTaskUnfoldController>> unfoldControllerProvider) {
         mContext = context;
         mDisplayId = displayId;
         mSyncQueue = syncQueue;
         mRootTDAOrganizer = rootTDAOrganizer;
         mTaskOrganizer = taskOrganizer;
         mLogger = logger;
+        mMainUnfoldController = unfoldControllerProvider.get().orElse(null);
+        mSideUnfoldController = unfoldControllerProvider.get().orElse(null);
+
         mMainStage = new MainStage(
                 mTaskOrganizer,
                 mDisplayId,
                 mMainStageListener,
                 mSyncQueue,
-                mSurfaceSession);
+                mSurfaceSession,
+                mMainUnfoldController);
         mSideStage = new SideStage(
                 mContext,
                 mTaskOrganizer,
                 mDisplayId,
                 mSideStageListener,
                 mSyncQueue,
-                mSurfaceSession);
+                mSurfaceSession,
+                mSideUnfoldController);
         mDisplayImeController = displayImeController;
         mDisplayInsetsController = displayInsetsController;
         mDisplayInsetsController.addInsetsChangedListener(mDisplayId, mSideStage);
@@ -218,7 +229,8 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             MainStage mainStage, SideStage sideStage, DisplayImeController displayImeController,
             DisplayInsetsController displayInsetsController, SplitLayout splitLayout,
             Transitions transitions, TransactionPool transactionPool,
-            SplitscreenEventLogger logger) {
+            SplitscreenEventLogger logger,
+            Provider<Optional<StageTaskUnfoldController>> unfoldControllerProvider) {
         mContext = context;
         mDisplayId = displayId;
         mSyncQueue = syncQueue;
@@ -232,6 +244,8 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         mSplitLayout = splitLayout;
         mSplitTransitions = new SplitScreenTransitions(transactionPool, transitions,
                 mOnTransitionAnimationComplete);
+        mMainUnfoldController = unfoldControllerProvider.get().orElse(null);
+        mSideUnfoldController = unfoldControllerProvider.get().orElse(null);
         mLogger = logger;
         transitions.addHandler(this);
     }
@@ -460,6 +474,7 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                 onLayoutChanged(mSplitLayout);
             } else {
                 updateWindowBounds(mSplitLayout, wct);
+                updateUnfoldBounds();
             }
         }
     }
@@ -603,6 +618,11 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             final SplitScreen.SplitScreenListener l = mListeners.get(i);
             l.onSplitVisibilityChanged(mDividerVisible);
         }
+
+        if (mMainUnfoldController != null && mSideUnfoldController != null) {
+            mMainUnfoldController.onSplitVisibilityChanged(mDividerVisible);
+            mSideUnfoldController.onSplitVisibilityChanged(mDividerVisible);
+        }
     }
 
     private void onStageRootTaskAppeared(StageListenerImpl stageListener) {
@@ -641,6 +661,7 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         mDividerVisible = visible;
         if (visible) {
             mSplitLayout.init();
+            updateUnfoldBounds();
         } else {
             mSplitLayout.release();
         }
@@ -784,12 +805,20 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
     public void onLayoutChanged(SplitLayout layout) {
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         updateWindowBounds(layout, wct);
+        updateUnfoldBounds();
         mSyncQueue.queue(wct);
         mSyncQueue.runInSync(t -> updateSurfaceBounds(layout, t));
         mSideStage.setOutlineVisibility(true);
         mLogger.logResize(mSplitLayout.getDividerPositionAsFraction());
     }
 
+    private void updateUnfoldBounds() {
+        if (mMainUnfoldController != null && mSideUnfoldController != null) {
+            mMainUnfoldController.onLayoutChanged(getMainStageBounds());
+            mSideUnfoldController.onLayoutChanged(getSideStageBounds());
+        }
+    }
+
     /**
      * Populates `wct` with operations that match the split windows to the current layout.
      * To match relevant surfaces, make sure to call updateSurfaceBounds after `wct` is applied
@@ -846,6 +875,11 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
                     mDisplayAreaInfo.configuration, this, mParentContainerCallbacks,
                     mDisplayImeController, mTaskOrganizer);
             mDisplayInsetsController.addInsetsChangedListener(mDisplayId, mSplitLayout);
+
+            if (mMainUnfoldController != null && mSideUnfoldController != null) {
+                mMainUnfoldController.init();
+                mSideUnfoldController.init();
+            }
         }
     }
 
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 4140332f50a3..84d570f4be44 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
@@ -24,6 +24,7 @@ import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
 import static com.android.wm.shell.transition.Transitions.ENABLE_SHELL_TRANSITIONS;
 
 import android.annotation.CallSuper;
+import android.annotation.Nullable;
 import android.app.ActivityManager;
 import android.graphics.Point;
 import android.graphics.Rect;
@@ -80,12 +81,16 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
     protected SparseArray<ActivityManager.RunningTaskInfo> mChildrenTaskInfo = new SparseArray<>();
     private final SparseArray<SurfaceControl> mChildrenLeashes = new SparseArray<>();
 
+    private final StageTaskUnfoldController mStageTaskUnfoldController;
+
     StageTaskListener(ShellTaskOrganizer taskOrganizer, int displayId,
             StageListenerCallbacks callbacks, SyncTransactionQueue syncQueue,
-            SurfaceSession surfaceSession) {
+            SurfaceSession surfaceSession,
+            @Nullable StageTaskUnfoldController stageTaskUnfoldController) {
         mCallbacks = callbacks;
         mSyncQueue = syncQueue;
         mSurfaceSession = surfaceSession;
+        mStageTaskUnfoldController = stageTaskUnfoldController;
         taskOrganizer.createRootTask(displayId, WINDOWING_MODE_MULTI_WINDOW, this);
     }
 
@@ -158,6 +163,10 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
             throw new IllegalArgumentException(this + "\n Unknown task: " + taskInfo
                     + "\n mRootTaskInfo: " + mRootTaskInfo);
         }
+
+        if (mStageTaskUnfoldController != null) {
+            mStageTaskUnfoldController.onTaskAppeared(taskInfo, leash);
+        }
     }
 
     @Override
@@ -210,6 +219,10 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
             throw new IllegalArgumentException(this + "\n Unknown task: " + taskInfo
                     + "\n mRootTaskInfo: " + mRootTaskInfo);
         }
+
+        if (mStageTaskUnfoldController != null) {
+            mStageTaskUnfoldController.onTaskVanished(taskInfo);
+        }
     }
 
     @Override
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskUnfoldController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskUnfoldController.java
new file mode 100644
index 000000000000..e904f6a9e22c
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskUnfoldController.java
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2021 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.splitscreen;
+
+import static android.view.Display.DEFAULT_DISPLAY;
+
+import android.animation.RectEvaluator;
+import android.animation.TypeEvaluator;
+import android.annotation.NonNull;
+import android.app.ActivityManager;
+import android.content.Context;
+import android.graphics.Rect;
+import android.util.SparseArray;
+import android.view.InsetsSource;
+import android.view.InsetsState;
+import android.view.SurfaceControl;
+
+import com.android.internal.policy.ScreenDecorationsUtils;
+import com.android.wm.shell.common.DisplayInsetsController;
+import com.android.wm.shell.common.DisplayInsetsController.OnInsetsChangedListener;
+import com.android.wm.shell.common.TransactionPool;
+import com.android.wm.shell.unfold.ShellUnfoldProgressProvider;
+import com.android.wm.shell.unfold.ShellUnfoldProgressProvider.UnfoldListener;
+import com.android.wm.shell.unfold.UnfoldBackgroundController;
+
+import java.util.concurrent.Executor;
+
+/**
+ * Controls transformations of the split screen task surfaces in response
+ * to the unfolding/folding action on foldable devices
+ */
+public class StageTaskUnfoldController implements UnfoldListener, OnInsetsChangedListener {
+
+    private static final TypeEvaluator<Rect> RECT_EVALUATOR = new RectEvaluator(new Rect());
+    private static final float CROPPING_START_MARGIN_FRACTION = 0.05f;
+
+    private final SparseArray<AnimationContext> mAnimationContextByTaskId = new SparseArray<>();
+    private final ShellUnfoldProgressProvider mUnfoldProgressProvider;
+    private final DisplayInsetsController mDisplayInsetsController;
+    private final UnfoldBackgroundController mBackgroundController;
+    private final Executor mExecutor;
+    private final int mExpandedTaskBarHeight;
+    private final float mWindowCornerRadiusPx;
+    private final Rect mStageBounds = new Rect();
+    private final TransactionPool mTransactionPool;
+
+    private InsetsSource mTaskbarInsetsSource;
+    private boolean mBothStagesVisible;
+
+    public StageTaskUnfoldController(@NonNull Context context,
+            @NonNull TransactionPool transactionPool,
+            @NonNull ShellUnfoldProgressProvider unfoldProgressProvider,
+            @NonNull DisplayInsetsController displayInsetsController,
+            @NonNull UnfoldBackgroundController backgroundController,
+            @NonNull Executor executor) {
+        mUnfoldProgressProvider = unfoldProgressProvider;
+        mTransactionPool = transactionPool;
+        mExecutor = executor;
+        mBackgroundController = backgroundController;
+        mDisplayInsetsController = displayInsetsController;
+        mWindowCornerRadiusPx = ScreenDecorationsUtils.getWindowCornerRadius(context);
+        mExpandedTaskBarHeight = context.getResources().getDimensionPixelSize(
+                com.android.internal.R.dimen.taskbar_frame_height);
+    }
+
+    /**
+     * Initializes the controller, starts listening for the external events
+     */
+    public void init() {
+        mUnfoldProgressProvider.addListener(mExecutor, this);
+        mDisplayInsetsController.addInsetsChangedListener(DEFAULT_DISPLAY, this);
+    }
+
+    @Override
+    public void insetsChanged(InsetsState insetsState) {
+        mTaskbarInsetsSource = insetsState.getSource(InsetsState.ITYPE_EXTRA_NAVIGATION_BAR);
+        for (int i = mAnimationContextByTaskId.size() - 1; i >= 0; i--) {
+            AnimationContext context = mAnimationContextByTaskId.valueAt(i);
+            context.update();
+        }
+    }
+
+    /**
+     * Called when split screen task appeared
+     * @param taskInfo info for the appeared task
+     * @param leash surface leash for the appeared task
+     */
+    public void onTaskAppeared(ActivityManager.RunningTaskInfo taskInfo, SurfaceControl leash) {
+        AnimationContext context = new AnimationContext(leash);
+        mAnimationContextByTaskId.put(taskInfo.taskId, context);
+    }
+
+    /**
+     * Called when a split screen task vanished
+     * @param taskInfo info for the vanished task
+     */
+    public void onTaskVanished(ActivityManager.RunningTaskInfo taskInfo) {
+        AnimationContext context = mAnimationContextByTaskId.get(taskInfo.taskId);
+        if (context != null) {
+            final SurfaceControl.Transaction transaction = mTransactionPool.acquire();
+            resetSurface(transaction, context);
+            transaction.apply();
+            mTransactionPool.release(transaction);
+        }
+        mAnimationContextByTaskId.remove(taskInfo.taskId);
+    }
+
+    @Override
+    public void onStateChangeProgress(float progress) {
+        if (mAnimationContextByTaskId.size() == 0 || !mBothStagesVisible) return;
+
+        final SurfaceControl.Transaction transaction = mTransactionPool.acquire();
+        mBackgroundController.ensureBackground(transaction);
+
+        for (int i = mAnimationContextByTaskId.size() - 1; i >= 0; i--) {
+            AnimationContext context = mAnimationContextByTaskId.valueAt(i);
+
+            context.mCurrentCropRect.set(RECT_EVALUATOR
+                    .evaluate(progress, context.mStartCropRect, context.mEndCropRect));
+
+            transaction.setWindowCrop(context.mLeash, context.mCurrentCropRect)
+                    .setCornerRadius(context.mLeash, mWindowCornerRadiusPx);
+        }
+
+        transaction.apply();
+
+        mTransactionPool.release(transaction);
+    }
+
+    @Override
+    public void onStateChangeFinished() {
+        resetTransformations();
+    }
+
+    /**
+     * Called when split screen visibility changes
+     * @param bothStagesVisible true if both stages of the split screen are visible
+     */
+    public void onSplitVisibilityChanged(boolean bothStagesVisible) {
+        mBothStagesVisible = bothStagesVisible;
+        if (!bothStagesVisible) {
+            resetTransformations();
+        }
+    }
+
+    /**
+     * Called when split screen stage bounds changed
+     * @param bounds new bounds for this stage
+     */
+    public void onLayoutChanged(Rect bounds) {
+        mStageBounds.set(bounds);
+
+        for (int i = mAnimationContextByTaskId.size() - 1; i >= 0; i--) {
+            final AnimationContext context = mAnimationContextByTaskId.valueAt(i);
+            context.update();
+        }
+    }
+
+    private void resetTransformations() {
+        final SurfaceControl.Transaction transaction = mTransactionPool.acquire();
+
+        for (int i = mAnimationContextByTaskId.size() - 1; i >= 0; i--) {
+            final AnimationContext context = mAnimationContextByTaskId.valueAt(i);
+            resetSurface(transaction, context);
+        }
+        mBackgroundController.removeBackground(transaction);
+        transaction.apply();
+
+        mTransactionPool.release(transaction);
+    }
+
+    private void resetSurface(SurfaceControl.Transaction transaction, AnimationContext context) {
+        transaction
+                .setWindowCrop(context.mLeash, null)
+                .setCornerRadius(context.mLeash, 0.0F);
+    }
+
+    private class AnimationContext {
+        final SurfaceControl mLeash;
+        final Rect mStartCropRect = new Rect();
+        final Rect mEndCropRect = new Rect();
+        final Rect mCurrentCropRect = new Rect();
+
+        private AnimationContext(SurfaceControl leash) {
+            this.mLeash = leash;
+            update();
+        }
+
+        private void update() {
+            mStartCropRect.set(mStageBounds);
+
+            if (mTaskbarInsetsSource != null) {
+                // Only insets the cropping window with taskbar when taskbar is expanded
+                if (mTaskbarInsetsSource.getFrame().height() >= mExpandedTaskBarHeight) {
+                    mStartCropRect.inset(mTaskbarInsetsSource
+                            .calculateVisibleInsets(mStartCropRect));
+                }
+            }
+
+            // Offset to surface coordinates as layout bounds are in screen coordinates
+            mStartCropRect.offsetTo(0, 0);
+
+            mEndCropRect.set(mStartCropRect);
+
+            int maxSize = Math.max(mEndCropRect.width(), mEndCropRect.height());
+            int margin = (int) (maxSize * CROPPING_START_MARGIN_FRACTION);
+            mStartCropRect.inset(margin, margin, margin, margin);
+        }
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/unfold/UnfoldBackgroundController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/unfold/UnfoldBackgroundController.java
new file mode 100644
index 000000000000..9faf454261d3
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/unfold/UnfoldBackgroundController.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2021 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.unfold;
+
+import static android.graphics.Color.blue;
+import static android.graphics.Color.green;
+import static android.graphics.Color.red;
+import static android.view.Display.DEFAULT_DISPLAY;
+
+import android.annotation.NonNull;
+import android.content.Context;
+import android.view.SurfaceControl;
+
+import com.android.wm.shell.R;
+import com.android.wm.shell.RootTaskDisplayAreaOrganizer;
+
+/**
+ * Controls background color layer for the unfold animations
+ */
+public class UnfoldBackgroundController {
+
+    private static final int BACKGROUND_LAYER_Z_INDEX = -1;
+
+    private final RootTaskDisplayAreaOrganizer mRootTaskDisplayAreaOrganizer;
+    private final float[] mBackgroundColor;
+    private SurfaceControl mBackgroundLayer;
+
+    public UnfoldBackgroundController(
+            @NonNull Context context,
+            @NonNull RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer) {
+        mRootTaskDisplayAreaOrganizer = rootTaskDisplayAreaOrganizer;
+        mBackgroundColor = getBackgroundColor(context);
+    }
+
+    /**
+     * Ensures that unfold animation background color layer is present,
+     * @param transaction where we should add the background if it is not added
+     */
+    public void ensureBackground(@NonNull SurfaceControl.Transaction transaction) {
+        if (mBackgroundLayer != null) return;
+
+        SurfaceControl.Builder colorLayerBuilder = new SurfaceControl.Builder()
+                .setName("app-unfold-background")
+                .setCallsite("AppUnfoldTransitionController")
+                .setColorLayer();
+        mRootTaskDisplayAreaOrganizer.attachToDisplayArea(DEFAULT_DISPLAY, colorLayerBuilder);
+        mBackgroundLayer = colorLayerBuilder.build();
+
+        transaction
+                .setColor(mBackgroundLayer, mBackgroundColor)
+                .show(mBackgroundLayer)
+                .setLayer(mBackgroundLayer, BACKGROUND_LAYER_Z_INDEX);
+    }
+
+    /**
+     * Ensures that the background is not visible
+     * @param transaction as part of which the removal will happen if needed
+     */
+    public void removeBackground(@NonNull SurfaceControl.Transaction transaction) {
+        if (mBackgroundLayer == null) return;
+        if (mBackgroundLayer.isValid()) {
+            transaction.remove(mBackgroundLayer);
+        }
+        mBackgroundLayer = null;
+    }
+
+    private float[] getBackgroundColor(Context context) {
+        int colorInt = context.getResources().getColor(R.color.unfold_transition_background);
+        return new float[]{
+                (float) red(colorInt) / 255.0F,
+                (float) green(colorInt) / 255.0F,
+                (float) blue(colorInt) / 255.0F
+        };
+    }
+}
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/MainStageTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/MainStageTests.java
index 1bb5fd1e49e7..12b547a765be 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/MainStageTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/MainStageTests.java
@@ -56,7 +56,7 @@ public class MainStageTests {
         MockitoAnnotations.initMocks(this);
         mRootTaskInfo = new TestRunningTaskInfoBuilder().build();
         mMainStage = new MainStage(mTaskOrganizer, DEFAULT_DISPLAY, mCallbacks, mSyncQueue,
-                mSurfaceSession);
+                mSurfaceSession, null);
         mMainStage.onTaskAppeared(mRootTaskInfo, mRootLeash);
     }
 
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SideStageTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SideStageTests.java
index 3a2516ec9366..838aa811bb87 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SideStageTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SideStageTests.java
@@ -64,7 +64,7 @@ public class SideStageTests extends ShellTestCase {
         MockitoAnnotations.initMocks(this);
         mRootTask = new TestRunningTaskInfoBuilder().build();
         mSideStage = new SideStage(mContext, mTaskOrganizer, DEFAULT_DISPLAY, mCallbacks,
-                mSyncQueue, mSurfaceSession);
+                mSyncQueue, mSurfaceSession, null);
         mSideStage.onTaskAppeared(mRootTask, mRootLeash);
     }
 
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTestUtils.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTestUtils.java
index 736566e5b4d3..f90af239db01 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTestUtils.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTestUtils.java
@@ -18,7 +18,6 @@ package com.android.wm.shell.splitscreen;
 
 import static android.view.Display.DEFAULT_DISPLAY;
 import static android.window.DisplayAreaOrganizer.FEATURE_DEFAULT_TASK_CONTAINER;
-
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 
@@ -39,6 +38,10 @@ import com.android.wm.shell.common.TransactionPool;
 import com.android.wm.shell.common.split.SplitLayout;
 import com.android.wm.shell.transition.Transitions;
 
+import java.util.Optional;
+
+import javax.inject.Provider;
+
 public class SplitTestUtils {
 
     static SplitLayout createMockSplitLayout() {
@@ -68,10 +71,11 @@ public class SplitTestUtils {
                 MainStage mainStage, SideStage sideStage, DisplayImeController imeController,
                 DisplayInsetsController insetsController, SplitLayout splitLayout,
                 Transitions transitions, TransactionPool transactionPool,
-                SplitscreenEventLogger logger) {
+                SplitscreenEventLogger logger,
+                Provider<Optional<StageTaskUnfoldController>> unfoldController) {
             super(context, displayId, syncQueue, rootTDAOrganizer, taskOrganizer, mainStage,
                     sideStage, imeController, insetsController, splitLayout, transitions,
-                    transactionPool, logger);
+                    transactionPool, logger, unfoldController);
 
             // Prepare default TaskDisplayArea for testing.
             mDisplayAreaInfo = new DisplayAreaInfo(
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTransitionTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTransitionTests.java
index 8dce454eb078..be103863a0f2 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTransitionTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/SplitTransitionTests.java
@@ -74,6 +74,8 @@ import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 import org.mockito.stubbing.Answer;
 
+import java.util.Optional;
+
 /** Tests for {@link StageCoordinator} */
 @SmallTest
 @RunWith(AndroidJUnit4.class)
@@ -106,16 +108,16 @@ public class SplitTransitionTests extends ShellTestCase {
         doReturn(mock(SurfaceControl.Transaction.class)).when(mTransactionPool).acquire();
         mSplitLayout = SplitTestUtils.createMockSplitLayout();
         mMainStage = new MainStage(mTaskOrganizer, DEFAULT_DISPLAY, mock(
-                StageTaskListener.StageListenerCallbacks.class), mSyncQueue, mSurfaceSession);
+                StageTaskListener.StageListenerCallbacks.class), mSyncQueue, mSurfaceSession, null);
         mMainStage.onTaskAppeared(new TestRunningTaskInfoBuilder().build(), createMockSurface());
         mSideStage = new SideStage(mContext, mTaskOrganizer, DEFAULT_DISPLAY, mock(
-                StageTaskListener.StageListenerCallbacks.class), mSyncQueue, mSurfaceSession);
+                StageTaskListener.StageListenerCallbacks.class), mSyncQueue, mSurfaceSession, null);
         mSideStage.onTaskAppeared(new TestRunningTaskInfoBuilder().build(), createMockSurface());
         mStageCoordinator = new SplitTestUtils.TestStageCoordinator(mContext, DEFAULT_DISPLAY,
                 mSyncQueue, mRootTDAOrganizer, mTaskOrganizer, mMainStage, mSideStage,
                 mDisplayImeController, mDisplayInsetsController, mSplitLayout, mTransitions,
                 mTransactionPool,
-                mLogger);
+                mLogger, Optional::empty);
         mSplitScreenTransitions = mStageCoordinator.getSplitTransitions();
         doAnswer((Answer<IBinder>) invocation -> mock(IBinder.class))
                 .when(mTransitions).startTransition(anyInt(), any(), any());
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java
index d930d4ca5dd4..a39d331ca884 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java
@@ -18,18 +18,20 @@ package com.android.wm.shell.splitscreen;
 
 import static android.app.ActivityTaskManager.INVALID_TASK_ID;
 import static android.view.Display.DEFAULT_DISPLAY;
-
 import static com.android.internal.util.FrameworkStatsLog.SPLITSCREEN_UICHANGED__EXIT_REASON__RETURN_HOME;
 import static com.android.wm.shell.common.split.SplitLayout.SPLIT_POSITION_BOTTOM_OR_RIGHT;
-
+import static com.android.wm.shell.common.split.SplitLayout.SPLIT_POSITION_TOP_OR_LEFT;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import android.app.ActivityManager;
 import android.graphics.Rect;
+import android.window.DisplayAreaInfo;
 import android.window.WindowContainerTransaction;
 
 import androidx.test.ext.junit.runners.AndroidJUnit4;
@@ -43,6 +45,7 @@ import com.android.wm.shell.common.DisplayImeController;
 import com.android.wm.shell.common.DisplayInsetsController;
 import com.android.wm.shell.common.SyncTransactionQueue;
 import com.android.wm.shell.common.TransactionPool;
+import com.android.wm.shell.common.split.SplitLayout;
 import com.android.wm.shell.transition.Transitions;
 
 import org.junit.Before;
@@ -51,29 +54,55 @@ import org.junit.runner.RunWith;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
-/** Tests for {@link StageCoordinator} */
+import java.util.Optional;
+
+import javax.inject.Provider;
+
+/**
+ * Tests for {@link StageCoordinator}
+ */
 @SmallTest
 @RunWith(AndroidJUnit4.class)
 public class StageCoordinatorTests extends ShellTestCase {
-    @Mock private ShellTaskOrganizer mTaskOrganizer;
-    @Mock private SyncTransactionQueue mSyncQueue;
-    @Mock private RootTaskDisplayAreaOrganizer mRootTDAOrganizer;
-    @Mock private MainStage mMainStage;
-    @Mock private SideStage mSideStage;
-    @Mock private DisplayImeController mDisplayImeController;
-    @Mock private DisplayInsetsController mDisplayInsetsController;
-    @Mock private Transitions mTransitions;
-    @Mock private TransactionPool mTransactionPool;
-    @Mock private SplitscreenEventLogger mLogger;
+    @Mock
+    private ShellTaskOrganizer mTaskOrganizer;
+    @Mock
+    private SyncTransactionQueue mSyncQueue;
+    @Mock
+    private RootTaskDisplayAreaOrganizer mRootTDAOrganizer;
+    @Mock
+    private MainStage mMainStage;
+    @Mock
+    private SideStage mSideStage;
+    @Mock
+    private StageTaskUnfoldController mMainUnfoldController;
+    @Mock
+    private StageTaskUnfoldController mSideUnfoldController;
+    @Mock
+    private SplitLayout mSplitLayout;
+    @Mock
+    private DisplayImeController mDisplayImeController;
+    @Mock
+    private DisplayInsetsController mDisplayInsetsController;
+    @Mock
+    private Transitions mTransitions;
+    @Mock
+    private TransactionPool mTransactionPool;
+    @Mock
+    private SplitscreenEventLogger mLogger;
+
+    private final Rect mBounds1 = new Rect(10, 20, 30, 40);
+    private final Rect mBounds2 = new Rect(5, 10, 15, 20);
+
     private StageCoordinator mStageCoordinator;
 
     @Before
     public void setup() {
         MockitoAnnotations.initMocks(this);
-        mStageCoordinator = new SplitTestUtils.TestStageCoordinator(mContext, DEFAULT_DISPLAY,
-                mSyncQueue, mRootTDAOrganizer, mTaskOrganizer, mMainStage, mSideStage,
-                mDisplayImeController, mDisplayInsetsController, null /* splitLayout */,
-                mTransitions, mTransactionPool, mLogger);
+        mStageCoordinator = createStageCoordinator(/* splitLayout */ null);
+
+        when(mSplitLayout.getBounds1()).thenReturn(mBounds1);
+        when(mSplitLayout.getBounds2()).thenReturn(mBounds2);
     }
 
     @Test
@@ -88,6 +117,38 @@ public class StageCoordinatorTests extends ShellTestCase {
     }
 
     @Test
+    public void testDisplayAreaAppeared_initializesUnfoldControllers() {
+        mStageCoordinator.onDisplayAreaAppeared(mock(DisplayAreaInfo.class));
+
+        verify(mMainUnfoldController).init();
+        verify(mSideUnfoldController).init();
+    }
+
+    @Test
+    public void testLayoutChanged_topLeftSplitPosition_updatesUnfoldStageBounds() {
+        mStageCoordinator = createStageCoordinator(mSplitLayout);
+        mStageCoordinator.setSideStagePosition(SPLIT_POSITION_TOP_OR_LEFT, null);
+        clearInvocations(mMainUnfoldController, mSideUnfoldController);
+
+        mStageCoordinator.onLayoutChanged(mSplitLayout);
+
+        verify(mMainUnfoldController).onLayoutChanged(mBounds2);
+        verify(mSideUnfoldController).onLayoutChanged(mBounds1);
+    }
+
+    @Test
+    public void testLayoutChanged_bottomRightSplitPosition_updatesUnfoldStageBounds() {
+        mStageCoordinator = createStageCoordinator(mSplitLayout);
+        mStageCoordinator.setSideStagePosition(SPLIT_POSITION_BOTTOM_OR_RIGHT, null);
+        clearInvocations(mMainUnfoldController, mSideUnfoldController);
+
+        mStageCoordinator.onLayoutChanged(mSplitLayout);
+
+        verify(mMainUnfoldController).onLayoutChanged(mBounds1);
+        verify(mSideUnfoldController).onLayoutChanged(mBounds2);
+    }
+
+    @Test
     public void testRemoveFromSideStage() {
         final ActivityManager.RunningTaskInfo task = new TestRunningTaskInfoBuilder().build();
 
@@ -131,4 +192,27 @@ public class StageCoordinatorTests extends ShellTestCase {
         verify(mSideStage).removeAllTasks(any(WindowContainerTransaction.class), eq(true));
         verify(mMainStage).deactivate(any(WindowContainerTransaction.class), eq(false));
     }
+
+    private StageCoordinator createStageCoordinator(SplitLayout splitLayout) {
+        return new SplitTestUtils.TestStageCoordinator(mContext, DEFAULT_DISPLAY,
+                mSyncQueue, mRootTDAOrganizer, mTaskOrganizer, mMainStage, mSideStage,
+                mDisplayImeController, mDisplayInsetsController, splitLayout,
+                mTransitions, mTransactionPool, mLogger, new UnfoldControllerProvider());
+    }
+
+    private class UnfoldControllerProvider implements
+            Provider<Optional<StageTaskUnfoldController>> {
+
+        private boolean isMain = true;
+
+        @Override
+        public Optional<StageTaskUnfoldController> get() {
+            if (isMain) {
+                isMain = false;
+                return Optional.of(mMainUnfoldController);
+            } else {
+                return Optional.of(mSideUnfoldController);
+            }
+        }
+    }
 }
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageTaskListenerTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageTaskListenerTests.java
index 0916dd1f71bd..a5746a49da2b 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageTaskListenerTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageTaskListenerTests.java
@@ -23,6 +23,7 @@ import static com.google.common.truth.Truth.assertThat;
 
 import static org.junit.Assume.assumeFalse;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 
@@ -60,6 +61,7 @@ public final class StageTaskListenerTests {
     @Mock private ShellTaskOrganizer mTaskOrganizer;
     @Mock private StageTaskListener.StageListenerCallbacks mCallbacks;
     @Mock private SyncTransactionQueue mSyncQueue;
+    @Mock private StageTaskUnfoldController mStageTaskUnfoldController;
     @Captor private ArgumentCaptor<SyncTransactionQueue.TransactionRunnable> mRunnableCaptor;
     private SurfaceSession mSurfaceSession = new SurfaceSession();
     private SurfaceControl mSurfaceControl;
@@ -74,7 +76,8 @@ public final class StageTaskListenerTests {
                 DEFAULT_DISPLAY,
                 mCallbacks,
                 mSyncQueue,
-                mSurfaceSession);
+                mSurfaceSession,
+                mStageTaskUnfoldController);
         mRootTask = new TestRunningTaskInfoBuilder().build();
         mRootTask.parentTaskId = INVALID_TASK_ID;
         mSurfaceControl = new SurfaceControl.Builder(mSurfaceSession).setName("test").build();
@@ -111,6 +114,28 @@ public final class StageTaskListenerTests {
         verify(mCallbacks).onStatusChanged(eq(mRootTask.isVisible), eq(true));
     }
 
+    @Test
+    public void testTaskAppeared_notifiesUnfoldListener() {
+        final ActivityManager.RunningTaskInfo task =
+                new TestRunningTaskInfoBuilder().setParentTaskId(mRootTask.taskId).build();
+
+        mStageTaskListener.onTaskAppeared(task, mSurfaceControl);
+
+        verify(mStageTaskUnfoldController).onTaskAppeared(eq(task), eq(mSurfaceControl));
+    }
+
+    @Test
+    public void testTaskVanished_notifiesUnfoldListener() {
+        final ActivityManager.RunningTaskInfo task =
+                new TestRunningTaskInfoBuilder().setParentTaskId(mRootTask.taskId).build();
+        mStageTaskListener.onTaskAppeared(task, mSurfaceControl);
+        clearInvocations(mStageTaskUnfoldController);
+
+        mStageTaskListener.onTaskVanished(task);
+
+        verify(mStageTaskUnfoldController).onTaskVanished(eq(task));
+    }
+
     @Test(expected = IllegalArgumentException.class)
     public void testUnknownTaskVanished() {
         final ActivityManager.RunningTaskInfo task = new TestRunningTaskInfoBuilder().build();
diff --git a/packages/SystemUI/src/com/android/systemui/wmshell/WMShellBaseModule.java b/packages/SystemUI/src/com/android/systemui/wmshell/WMShellBaseModule.java
index ff263109d555..514a9035a9ef 100644
--- a/packages/SystemUI/src/com/android/systemui/wmshell/WMShellBaseModule.java
+++ b/packages/SystemUI/src/com/android/systemui/wmshell/WMShellBaseModule.java
@@ -73,6 +73,7 @@ import com.android.wm.shell.pip.phone.PipTouchHandler;
 import com.android.wm.shell.sizecompatui.SizeCompatUIController;
 import com.android.wm.shell.splitscreen.SplitScreen;
 import com.android.wm.shell.splitscreen.SplitScreenController;
+import com.android.wm.shell.splitscreen.StageTaskUnfoldController;
 import com.android.wm.shell.startingsurface.StartingSurface;
 import com.android.wm.shell.startingsurface.StartingWindowController;
 import com.android.wm.shell.startingsurface.StartingWindowTypeAlgorithm;
@@ -81,10 +82,14 @@ import com.android.wm.shell.tasksurfacehelper.TaskSurfaceHelperController;
 import com.android.wm.shell.transition.ShellTransitions;
 import com.android.wm.shell.transition.Transitions;
 import com.android.wm.shell.unfold.ShellUnfoldProgressProvider;
+import com.android.wm.shell.unfold.UnfoldBackgroundController;
 
 import java.util.Optional;
 
+import javax.inject.Provider;
+
 import dagger.BindsOptionalOf;
+import dagger.Lazy;
 import dagger.Module;
 import dagger.Provides;
 
@@ -234,16 +239,48 @@ public abstract class WMShellBaseModule {
     static Optional<FullscreenUnfoldController> provideFullscreenUnfoldController(
             Context context,
             Optional<ShellUnfoldProgressProvider> progressProvider,
-            RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
+            Lazy<UnfoldBackgroundController> unfoldBackgroundController,
             DisplayInsetsController displayInsetsController,
             @ShellMainThread ShellExecutor mainExecutor
     ) {
         return progressProvider.map(shellUnfoldTransitionProgressProvider ->
                 new FullscreenUnfoldController(context, mainExecutor,
-                        shellUnfoldTransitionProgressProvider, rootTaskDisplayAreaOrganizer,
+                        unfoldBackgroundController.get(), shellUnfoldTransitionProgressProvider,
                         displayInsetsController));
     }
 
+    @Provides
+    static Optional<StageTaskUnfoldController> provideStageTaskUnfoldController(
+            Optional<ShellUnfoldProgressProvider> progressProvider,
+            Context context,
+            TransactionPool transactionPool,
+            Lazy<UnfoldBackgroundController> unfoldBackgroundController,
+            DisplayInsetsController displayInsetsController,
+            @ShellMainThread ShellExecutor mainExecutor
+    ) {
+        return progressProvider.map(shellUnfoldTransitionProgressProvider ->
+                new StageTaskUnfoldController(
+                        context,
+                        transactionPool,
+                        shellUnfoldTransitionProgressProvider,
+                        displayInsetsController,
+                        unfoldBackgroundController.get(),
+                        mainExecutor
+                ));
+    }
+
+    @WMSingleton
+    @Provides
+    static UnfoldBackgroundController provideUnfoldBackgroundController(
+            RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
+            Context context
+    ) {
+        return new UnfoldBackgroundController(
+                context,
+                rootTaskDisplayAreaOrganizer
+        );
+    }
+
     //
     // Freeform (optional feature)
     //
@@ -401,12 +438,13 @@ public abstract class WMShellBaseModule {
             @ShellMainThread ShellExecutor mainExecutor,
             DisplayImeController displayImeController,
             DisplayInsetsController displayInsetsController, Transitions transitions,
-            TransactionPool transactionPool) {
+            TransactionPool transactionPool,
+            Provider<Optional<StageTaskUnfoldController>> stageTaskUnfoldControllerProvider) {
         if (ActivityTaskManager.supportsSplitScreenMultiWindow(context)) {
             return Optional.of(new SplitScreenController(shellTaskOrganizer, syncQueue, context,
                     rootTaskDisplayAreaOrganizer, mainExecutor, displayImeController,
                     displayInsetsController, transitions,
-                    transactionPool));
+                    transactionPool, stageTaskUnfoldControllerProvider));
         } else {
             return Optional.empty();
         }