Animation For Fullscreen -> Freeform Transition

When dragged below the status bar, the task transitions to 40% of its
original size. If the task is released below the status bar, it will
use shell transitions to animate from 40 to 60 percent.

Bug: 266973706
Test: Manual Testing
Change-Id: Ia3237db751192816dded46c8898a9b383703c993

libs/WindowManager/Shell/src/com/android/wm/shell/dagger/WMShellModule.java

@@ -54,6 +54,7 @@ import com.android.wm.shell.desktopmode.DesktopModeController;
 import com.android.wm.shell.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.desktopmode.DesktopModeTaskRepository;
 import com.android.wm.shell.desktopmode.DesktopTasksController;
+import com.android.wm.shell.desktopmode.EnterDesktopTaskTransitionHandler;
 import com.android.wm.shell.draganddrop.DragAndDropController;
 import com.android.wm.shell.freeform.FreeformComponents;
 import com.android.wm.shell.freeform.FreeformTaskListener;
@@ -676,12 +677,20 @@ public abstract class WMShellModule {
             SyncTransactionQueue syncQueue,
             RootTaskDisplayAreaOrganizer rootTaskDisplayAreaOrganizer,
             Transitions transitions,
+            EnterDesktopTaskTransitionHandler transitionHandler,
             @DynamicOverride DesktopModeTaskRepository desktopModeTaskRepository,
             @ShellMainThread ShellExecutor mainExecutor
     ) {
         return new DesktopTasksController(context, shellInit, shellController, displayController,
                 shellTaskOrganizer, syncQueue, rootTaskDisplayAreaOrganizer, transitions,
-                desktopModeTaskRepository, mainExecutor);
+                transitionHandler, desktopModeTaskRepository, mainExecutor);
+    }
+
+    @WMSingleton
+    @Provides
+    static EnterDesktopTaskTransitionHandler provideEnterDesktopModeTaskTransitionHandler(
+            Transitions transitions) {
+        return new EnterDesktopTaskTransitionHandler(transitions);
     }
 
     @WMSingleton

libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopTasksController.kt

@@ -25,6 +25,7 @@ import android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN
 import android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED
 import android.app.WindowConfiguration.WindowingMode
 import android.content.Context
+import android.graphics.Rect
 import android.os.IBinder
 import android.os.SystemProperties
 import android.view.SurfaceControl
@@ -67,6 +68,7 @@ class DesktopTasksController(
         private val syncQueue: SyncTransactionQueue,
         private val rootTaskDisplayAreaOrganizer: RootTaskDisplayAreaOrganizer,
         private val transitions: Transitions,
+        private val animationTransitionHandler: EnterDesktopTaskTransitionHandler,
         private val desktopModeTaskRepository: DesktopModeTaskRepository,
         @ShellMainThread private val mainExecutor: ShellExecutor
 ) : RemoteCallable<DesktopTasksController>, Transitions.TransitionHandler {
@@ -133,6 +135,44 @@ class DesktopTasksController(
         }
     }
 
+    /**
+     * Moves a single task to freeform and sets the taskBounds to the passed in bounds,
+     * startBounds
+     */
+    fun moveToFreeform(
+            taskInfo: RunningTaskInfo,
+            startBounds: Rect
+    ) {
+        val wct = WindowContainerTransaction()
+        moveHomeTaskToFront(wct)
+        addMoveToDesktopChanges(wct, taskInfo.getToken())
+        wct.setBounds(taskInfo.token, startBounds)
+
+        if (Transitions.ENABLE_SHELL_TRANSITIONS) {
+            animationTransitionHandler.startTransition(
+                    Transitions.TRANSIT_ENTER_FREEFORM, wct)
+        } else {
+            shellTaskOrganizer.applyTransaction(wct)
+        }
+    }
+
+    /** Brings apps to front and sets freeform task bounds */
+    fun moveToDesktopWithAnimation(
+            taskInfo: RunningTaskInfo,
+            freeformBounds: Rect
+    ) {
+        val wct = WindowContainerTransaction()
+        bringDesktopAppsToFront(wct)
+        addMoveToDesktopChanges(wct, taskInfo.getToken())
+        wct.setBounds(taskInfo.token, freeformBounds)
+
+        if (Transitions.ENABLE_SHELL_TRANSITIONS) {
+            animationTransitionHandler.startTransition(Transitions.TRANSIT_ENTER_DESKTOP_MODE, wct)
+        } else {
+            shellTaskOrganizer.applyTransaction(wct)
+        }
+    }
+
     /** Move a task with given `taskId` to fullscreen */
     fun moveToFullscreen(taskId: Int) {
         shellTaskOrganizer.getRunningTaskInfo(taskId)?.let { task -> moveToFullscreen(task) }

libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/EnterDesktopTaskTransitionHandler.java

@@ -0,0 +1,185 @@
+/*
+ * Copyright (C) 2023 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.desktopmode;
+
+import static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.ValueAnimator;
+import android.app.ActivityManager;
+import android.graphics.Rect;
+import android.os.IBinder;
+import android.view.SurfaceControl;
+import android.view.WindowManager;
+import android.window.TransitionInfo;
+import android.window.TransitionRequestInfo;
+import android.window.WindowContainerTransaction;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.android.wm.shell.transition.Transitions;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * The {@link Transitions.TransitionHandler} that handles transitions for desktop mode tasks
+ * entering and exiting freeform.
+ */
+public class EnterDesktopTaskTransitionHandler implements Transitions.TransitionHandler {
+
+    private final Transitions mTransitions;
+    private final Supplier<SurfaceControl.Transaction> mTransactionSupplier;
+
+    // The size of the screen during drag relative to the fullscreen size
+    public static final float DRAG_FREEFORM_SCALE = 0.4f;
+    // The size of the screen after drag relative to the fullscreen size
+    public static final float FINAL_FREEFORM_SCALE = 0.6f;
+    public static final int FREEFORM_ANIMATION_DURATION = 336;
+
+    private final List<IBinder> mPendingTransitionTokens = new ArrayList<>();
+
+    public EnterDesktopTaskTransitionHandler(
+            Transitions transitions) {
+        this(transitions, SurfaceControl.Transaction::new);
+    }
+
+    public EnterDesktopTaskTransitionHandler(
+            Transitions transitions,
+            Supplier<SurfaceControl.Transaction> supplier) {
+        mTransitions = transitions;
+        mTransactionSupplier = supplier;
+    }
+
+    /**
+     * Starts Transition of a given type
+     * @param type Transition type
+     * @param wct WindowContainerTransaction for transition
+     */
+    public void startTransition(@WindowManager.TransitionType int type,
+                @NonNull WindowContainerTransaction wct) {
+        final IBinder token = mTransitions.startTransition(type, wct, this);
+        mPendingTransitionTokens.add(token);
+    }
+
+    @Override
+    public boolean startAnimation(@NonNull IBinder transition, @NonNull TransitionInfo info,
+            @NonNull SurfaceControl.Transaction startT,
+            @NonNull SurfaceControl.Transaction finishT,
+            @NonNull Transitions.TransitionFinishCallback finishCallback) {
+        boolean transitionHandled = false;
+        for (TransitionInfo.Change change : info.getChanges()) {
+            if ((change.getFlags() & TransitionInfo.FLAG_IS_WALLPAPER) != 0) {
+                continue;
+            }
+
+            final ActivityManager.RunningTaskInfo taskInfo = change.getTaskInfo();
+            if (taskInfo == null || taskInfo.taskId == -1) {
+                continue;
+            }
+
+            if (change.getMode() == WindowManager.TRANSIT_CHANGE) {
+                transitionHandled |= startChangeTransition(
+                        transition, info.getType(), change, startT, finishCallback);
+            }
+        }
+
+        mPendingTransitionTokens.remove(transition);
+
+        return transitionHandled;
+    }
+
+    private boolean startChangeTransition(
+            @NonNull IBinder transition,
+            @WindowManager.TransitionType int type,
+            @NonNull TransitionInfo.Change change,
+            @NonNull SurfaceControl.Transaction startT,
+            @NonNull Transitions.TransitionFinishCallback finishCallback) {
+        if (!mPendingTransitionTokens.contains(transition)) {
+            return false;
+        }
+
+        final ActivityManager.RunningTaskInfo taskInfo = change.getTaskInfo();
+        if (type == Transitions.TRANSIT_ENTER_FREEFORM
+                && taskInfo.getWindowingMode() == WINDOWING_MODE_FREEFORM) {
+            // Transitioning to freeform but keeping fullscreen bounds, so the crop is set
+            // to null and we don't require an animation
+            final SurfaceControl sc = change.getLeash();
+            startT.setWindowCrop(sc, null);
+            startT.apply();
+            mTransitions.getMainExecutor().execute(
+                    () -> finishCallback.onTransitionFinished(null, null));
+            return true;
+        }
+
+        Rect endBounds = change.getEndAbsBounds();
+        if (type == Transitions.TRANSIT_ENTER_DESKTOP_MODE
+                && taskInfo.getWindowingMode() == WINDOWING_MODE_FREEFORM
+                && !endBounds.isEmpty()) {
+            // This Transition animates a task to freeform bounds after being dragged into freeform
+            // mode and brings the remaining freeform tasks to front
+            final SurfaceControl sc = change.getLeash();
+            startT.setWindowCrop(sc, endBounds.width(),
+                    endBounds.height());
+            startT.apply();
+
+            // We want to find the scale of the current bounds relative to the end bounds. The
+            // task is currently scaled to DRAG_FREEFORM_SCALE and the final bounds will be
+            // scaled to FINAL_FREEFORM_SCALE. So, it is scaled to
+            // DRAG_FREEFORM_SCALE / FINAL_FREEFORM_SCALE relative to the freeform bounds
+            final ValueAnimator animator =
+                    ValueAnimator.ofFloat(DRAG_FREEFORM_SCALE / FINAL_FREEFORM_SCALE, 1f);
+            animator.setDuration(FREEFORM_ANIMATION_DURATION);
+            final SurfaceControl.Transaction t = mTransactionSupplier.get();
+            animator.addUpdateListener(animation -> {
+                final float animationValue = (float) animation.getAnimatedValue();
+                t.setScale(sc, animationValue, animationValue);
+
+                final float animationWidth = endBounds.width() * animationValue;
+                final float animationHeight = endBounds.height() * animationValue;
+                final int animationX = endBounds.centerX() - (int) (animationWidth / 2);
+                final int animationY = endBounds.centerY() - (int) (animationHeight / 2);
+
+                t.setPosition(sc, animationX, animationY);
+                t.apply();
+            });
+
+            animator.addListener(new AnimatorListenerAdapter() {
+                @Override
+                public void onAnimationEnd(Animator animation) {
+                    mTransitions.getMainExecutor().execute(
+                            () -> finishCallback.onTransitionFinished(null, null));
+                }
+            });
+
+            animator.start();
+            return true;
+        }
+
+        return false;
+    }
+
+    @Nullable
+    @Override
+    public WindowContainerTransaction handleRequest(@NonNull IBinder transition,
+            @NonNull TransitionRequestInfo request) {
+        return null;
+    }
+}

libs/WindowManager/Shell/src/com/android/wm/shell/freeform/FreeformTaskTransitionObserver.java

@@ -112,6 +112,7 @@ public class FreeformTaskTransitionObserver implements Transitions.TransitionObs
                     onChangeTransitionReady(change, startT, finishT);
                     break;
             }
+            mWindowDecorViewModel.onTransitionReady(transition, info, change);
         }
         mTransitionToTaskInfo.put(transition, taskInfoList);
     }
@@ -168,6 +169,8 @@ public class FreeformTaskTransitionObserver implements Transitions.TransitionObs
         } else {
             mTransitionToTaskInfo.put(playing, infoOfMerged);
         }
+
+        mWindowDecorViewModel.onTransitionMerged(merged, playing);
     }
 
     @Override
@@ -175,7 +178,7 @@ public class FreeformTaskTransitionObserver implements Transitions.TransitionObs
         final List<ActivityManager.RunningTaskInfo> taskInfo =
                 mTransitionToTaskInfo.getOrDefault(transition, Collections.emptyList());
         mTransitionToTaskInfo.remove(transition);
-
+        mWindowDecorViewModel.onTransitionFinished(transition);
         for (int i = 0; i < taskInfo.size(); ++i) {
             mWindowDecorViewModel.destroyWindowDecoration(taskInfo.get(i));
         }

libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java

@@ -133,6 +133,12 @@ public class Transitions implements RemoteCallable<Transitions> {
     /** Transition type for maximize to freeform transition. */
     public static final int TRANSIT_RESTORE_FROM_MAXIMIZE = WindowManager.TRANSIT_FIRST_CUSTOM + 9;
 
+    /** Transition type to freeform in desktop mode. */
+    public static final int TRANSIT_ENTER_FREEFORM = WindowManager.TRANSIT_FIRST_CUSTOM + 10;
+
+    /** Transition type to freeform in desktop mode. */
+    public static final int TRANSIT_ENTER_DESKTOP_MODE = WindowManager.TRANSIT_FIRST_CUSTOM + 11;
+
     private final WindowOrganizer mOrganizer;
     private final Context mContext;
     private final ShellExecutor mMainExecutor;

libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/CaptionWindowDecorViewModel.java

@@ -23,11 +23,13 @@ import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import android.app.ActivityManager.RunningTaskInfo;
 import android.content.Context;
 import android.os.Handler;
+import android.os.IBinder;
 import android.util.SparseArray;
 import android.view.Choreographer;
 import android.view.MotionEvent;
 import android.view.SurfaceControl;
 import android.view.View;
+import android.window.TransitionInfo;
 import android.window.WindowContainerToken;
 import android.window.WindowContainerTransaction;
 
@@ -71,6 +73,16 @@ public class CaptionWindowDecorViewModel implements WindowDecorViewModel {
         }
     }
 
+    @Override
+    public void onTransitionReady(IBinder transition, TransitionInfo info,
+            TransitionInfo.Change change) {}
+
+    @Override
+    public void onTransitionMerged(IBinder merged, IBinder playing) {}
+
+    @Override
+    public void onTransitionFinished(IBinder transition) {}
+
     @Override
     public void setFreeformTaskTransitionStarter(FreeformTaskTransitionStarter transitionStarter) {
         mTaskOperations = new TaskOperations(transitionStarter, mContext, mSyncQueue);

libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModel.java

@@ -22,7 +22,11 @@ import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 
 import static com.android.wm.shell.common.split.SplitScreenConstants.SPLIT_POSITION_BOTTOM_OR_RIGHT;
 import static com.android.wm.shell.common.split.SplitScreenConstants.SPLIT_POSITION_TOP_OR_LEFT;
+import static com.android.wm.shell.desktopmode.EnterDesktopTaskTransitionHandler.DRAG_FREEFORM_SCALE;
+import static com.android.wm.shell.desktopmode.EnterDesktopTaskTransitionHandler.FINAL_FREEFORM_SCALE;
+import static com.android.wm.shell.desktopmode.EnterDesktopTaskTransitionHandler.FREEFORM_ANIMATION_DURATION;
 
+import android.animation.ValueAnimator;
 import android.app.ActivityManager;
 import android.app.ActivityManager.RunningTaskInfo;
 import android.app.ActivityTaskManager;
@@ -30,6 +34,7 @@ import android.content.Context;
 import android.graphics.Rect;
 import android.hardware.input.InputManager;
 import android.os.Handler;
+import android.os.IBinder;
 import android.os.Looper;
 import android.util.SparseArray;
 import android.view.Choreographer;
@@ -39,9 +44,13 @@ import android.view.InputEventReceiver;
 import android.view.InputMonitor;
 import android.view.MotionEvent;
 import android.view.SurfaceControl;
+import android.view.SurfaceControl.Transaction;
 import android.view.View;
+import android.view.WindowManager;
+import android.window.TransitionInfo;
 import android.window.WindowContainerToken;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.internal.annotations.VisibleForTesting;
@@ -54,8 +63,10 @@ import com.android.wm.shell.desktopmode.DesktopModeStatus;
 import com.android.wm.shell.desktopmode.DesktopTasksController;
 import com.android.wm.shell.freeform.FreeformTaskTransitionStarter;
 import com.android.wm.shell.splitscreen.SplitScreenController;
+import com.android.wm.shell.transition.Transitions;
 
 import java.util.Optional;
+import java.util.function.Supplier;
 
 /**
  * View model for the window decoration with a caption and shadows. Works with
@@ -83,9 +94,20 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
     private final DragStartListenerImpl mDragStartListener = new DragStartListenerImpl();
     private final InputMonitorFactory mInputMonitorFactory;
     private TaskOperations mTaskOperations;
+    private final Supplier<SurfaceControl.Transaction> mTransactionFactory;
 
     private Optional<SplitScreenController> mSplitScreenController;
 
+    private ValueAnimator mDragToDesktopValueAnimator;
+    private final Rect mDragToDesktopAnimationStartBounds = new Rect();
+    private boolean mDragToDesktopAnimationStarted;
+    private float mCaptionDragStartX;
+
+    // These values keep track of any transitions to freeform to stop relayout from running on
+    // changing task so that shellTransitions has a chance to animate the transition
+    private int mPauseRelayoutForTask = -1;
+    private IBinder mTransitionPausingRelayout;
+
     public DesktopModeWindowDecorViewModel(
             Context context,
             Handler mainHandler,
@@ -107,7 +129,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
                 desktopTasksController,
                 splitScreenController,
                 new DesktopModeWindowDecoration.Factory(),
-                new InputMonitorFactory());
+                new InputMonitorFactory(),
+                SurfaceControl.Transaction::new);
     }
 
     @VisibleForTesting
@@ -122,7 +145,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             Optional<DesktopTasksController> desktopTasksController,
             Optional<SplitScreenController> splitScreenController,
             DesktopModeWindowDecoration.Factory desktopModeWindowDecorFactory,
-            InputMonitorFactory inputMonitorFactory) {
+            InputMonitorFactory inputMonitorFactory,
+            Supplier<SurfaceControl.Transaction> transactionFactory) {
         mContext = context;
         mMainHandler = mainHandler;
         mMainChoreographer = mainChoreographer;
@@ -136,6 +160,7 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
 
         mDesktopModeWindowDecorFactory = desktopModeWindowDecorFactory;
         mInputMonitorFactory = inputMonitorFactory;
+        mTransactionFactory = transactionFactory;
     }
 
     @Override
@@ -154,6 +179,31 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
         return true;
     }
 
+    @Override
+    public void onTransitionReady(
+            @NonNull IBinder transition,
+            @NonNull TransitionInfo info,
+            @NonNull TransitionInfo.Change change) {
+        if (change.getMode() == WindowManager.TRANSIT_CHANGE
+                && info.getType() == Transitions.TRANSIT_ENTER_DESKTOP_MODE) {
+            mTransitionPausingRelayout = transition;
+        }
+    }
+
+    @Override
+    public void onTransitionMerged(@NonNull IBinder merged, @NonNull IBinder playing) {
+        if (mTransitionPausingRelayout.equals(merged)) {
+            mTransitionPausingRelayout = playing;
+        }
+    }
+
+    @Override
+    public void onTransitionFinished(@NonNull IBinder transition) {
+        if (transition.equals(mTransitionPausingRelayout)) {
+            mPauseRelayoutForTask = -1;
+        }
+    }
+
     @Override
     public void onTaskInfoChanged(RunningTaskInfo taskInfo) {
         final DesktopModeWindowDecoration decoration = mWindowDecorByTaskId.get(taskInfo.taskId);
@@ -165,7 +215,12 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             incrementEventReceiverTasks(taskInfo.displayId);
         }
 
-        decoration.relayout(taskInfo);
+        // TaskListener callbacks and shell transitions aren't synchronized, so starting a shell
+        // transition can trigger an onTaskInfoChanged call that updates the task's SurfaceControl
+        // and interferes with the transition animation that is playing at the same time.
+        if (taskInfo.taskId != mPauseRelayoutForTask) {
+            decoration.relayout(taskInfo);
+        }
     }
 
     @Override
@@ -295,7 +350,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
                 case MotionEvent.ACTION_DOWN: {
                     mDragPointerId = e.getPointerId(0);
                     mDragPositioningCallback.onDragPositioningStart(
-                            0 /* ctrlType */, e.getRawX(0), e.getRawY(0));
+                            0 /* ctrlType */, e.getRawX(0),
+                            e.getRawY(0));
                     mIsDragging = false;
                     return false;
                 }
@@ -403,7 +459,8 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
         final DesktopModeWindowDecoration relevantDecor = getRelevantWindowDecor(ev);
         if (DesktopModeStatus.isProto2Enabled()) {
             if (relevantDecor == null
-                    || relevantDecor.mTaskInfo.getWindowingMode() != WINDOWING_MODE_FREEFORM) {
+                    || relevantDecor.mTaskInfo.getWindowingMode() != WINDOWING_MODE_FREEFORM
+                    || mTransitionDragActive) {
                 handleCaptionThroughStatusBar(ev, relevantDecor);
             }
         }
@@ -444,8 +501,11 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             DesktopModeWindowDecoration relevantDecor) {
         switch (ev.getActionMasked()) {
             case MotionEvent.ACTION_DOWN: {
+                mCaptionDragStartX = ev.getX();
                 // Begin drag through status bar if applicable.
                 if (relevantDecor != null) {
+                    mDragToDesktopAnimationStartBounds.set(
+                            relevantDecor.mTaskInfo.configuration.windowConfiguration.getBounds());
                     boolean dragFromStatusBarAllowed = false;
                     if (DesktopModeStatus.isProto2Enabled()) {
                         // In proto2 any full screen task can be dragged to freeform
@@ -461,33 +521,105 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
             }
             case MotionEvent.ACTION_UP: {
                 if (relevantDecor == null) {
+                    mDragToDesktopAnimationStarted = false;
                     mTransitionDragActive = false;
                     return;
                 }
                 if (mTransitionDragActive) {
                     mTransitionDragActive = false;
-                    final int statusBarHeight = mDisplayController
-                            .getDisplayLayout(relevantDecor.mTaskInfo.displayId).stableInsets().top;
+                    final int statusBarHeight = getStatusBarHeight(
+                            relevantDecor.mTaskInfo.displayId);
                     if (ev.getY() > statusBarHeight) {
                         if (DesktopModeStatus.isProto2Enabled()) {
+                            mPauseRelayoutForTask = relevantDecor.mTaskInfo.taskId;
                             mDesktopTasksController.ifPresent(
-                                    c -> c.moveToDesktop(relevantDecor.mTaskInfo));
+                                    c -> c.moveToDesktopWithAnimation(relevantDecor.mTaskInfo,
+                                            getFreeformBounds(ev)));
                         } else if (DesktopModeStatus.isProto1Enabled()) {
                             mDesktopModeController.ifPresent(c -> c.setDesktopModeActive(true));
                         }
-
+                        mDragToDesktopAnimationStarted = false;
+                        return;
+                    } else if (mDragToDesktopAnimationStarted) {
+                        mDesktopTasksController.ifPresent(c ->
+                                c.moveToFullscreen(relevantDecor.mTaskInfo));
+                        mDragToDesktopAnimationStarted = false;
                         return;
                     }
                 }
                 relevantDecor.checkClickEvent(ev);
                 break;
             }
+
+            case MotionEvent.ACTION_MOVE: {
+                if (relevantDecor == null) {
+                    return;
+                }
+                if (mTransitionDragActive) {
+                    final int statusBarHeight = mDisplayController
+                            .getDisplayLayout(
+                                    relevantDecor.mTaskInfo.displayId).stableInsets().top;
+                    if (ev.getY() > statusBarHeight) {
+                        if (!mDragToDesktopAnimationStarted) {
+                            mDragToDesktopAnimationStarted = true;
+                            mDesktopTasksController.ifPresent(
+                                    c -> c.moveToFreeform(relevantDecor.mTaskInfo,
+                                            mDragToDesktopAnimationStartBounds));
+                            startAnimation(relevantDecor);
+                        }
+                    }
+                    if (mDragToDesktopAnimationStarted) {
+                        Transaction t = mTransactionFactory.get();
+                        float width = (float) mDragToDesktopValueAnimator.getAnimatedValue()
+                                * mDragToDesktopAnimationStartBounds.width();
+                        float x = ev.getX() - (width / 2);
+                        t.setPosition(relevantDecor.mTaskSurface, x, ev.getY());
+                        t.apply();
+                    }
+                }
+                break;
+            }
+
             case MotionEvent.ACTION_CANCEL: {
                 mTransitionDragActive = false;
+                mDragToDesktopAnimationStarted = false;
             }
         }
     }
 
+    private Rect getFreeformBounds(@NonNull MotionEvent ev) {
+        final Rect endBounds = new Rect();
+        final int finalWidth = (int) (FINAL_FREEFORM_SCALE
+                * mDragToDesktopAnimationStartBounds.width());
+        final int finalHeight = (int) (FINAL_FREEFORM_SCALE
+                * mDragToDesktopAnimationStartBounds.height());
+
+        endBounds.left = mDragToDesktopAnimationStartBounds.centerX() - finalWidth / 2
+                + (int) (ev.getX() - mCaptionDragStartX);
+        endBounds.right = endBounds.left + (int) (FINAL_FREEFORM_SCALE
+                * mDragToDesktopAnimationStartBounds.width());
+        endBounds.top = (int) (ev.getY()
+                - ((FINAL_FREEFORM_SCALE - DRAG_FREEFORM_SCALE)
+                * mDragToDesktopAnimationStartBounds.height() / 2));
+        endBounds.bottom = endBounds.top + finalHeight;
+
+        return endBounds;
+    }
+
+    private void startAnimation(@NonNull DesktopModeWindowDecoration focusedDecor) {
+        mDragToDesktopValueAnimator = ValueAnimator.ofFloat(1f, DRAG_FREEFORM_SCALE);
+        mDragToDesktopValueAnimator.setDuration(FREEFORM_ANIMATION_DURATION);
+        final Transaction t = mTransactionFactory.get();
+        mDragToDesktopValueAnimator.addUpdateListener(animation -> {
+            final float animatorValue = (float) animation.getAnimatedValue();
+            SurfaceControl sc = focusedDecor.mTaskSurface;
+            t.setScale(sc, animatorValue, animatorValue);
+            t.apply();
+        });
+
+        mDragToDesktopValueAnimator.start();
+    }
+
     @Nullable
     private DesktopModeWindowDecoration getRelevantWindowDecor(MotionEvent ev) {
         if (mSplitScreenController.isPresent()
@@ -534,6 +666,10 @@ public class DesktopModeWindowDecorViewModel implements WindowDecorViewModel {
         return focusedDecor;
     }
 
+    private int getStatusBarHeight(int displayId) {
+        return mDisplayController.getDisplayLayout(displayId).stableInsets().top;
+    }
+
     private void createInputChannel(int displayId) {
         final InputManager inputManager = mContext.getSystemService(InputManager.class);
         final InputMonitor inputMonitor =

libs/WindowManager/Shell/src/com/android/wm/shell/windowdecor/WindowDecorViewModel.java

@@ -17,7 +17,9 @@
 package com.android.wm.shell.windowdecor;
 
 import android.app.ActivityManager;
+import android.os.IBinder;
 import android.view.SurfaceControl;
+import android.window.TransitionInfo;
 
 import com.android.wm.shell.freeform.FreeformTaskTransitionStarter;
 
@@ -95,4 +97,34 @@ public interface WindowDecorViewModel {
      * @param taskInfo the info of the task
      */
     void destroyWindowDecoration(ActivityManager.RunningTaskInfo taskInfo);
+
+    /**
+     * Notifies that a shell transition is about to start. If the transition is of type
+     * TRANSIT_ENTER_DESKTOP, it will save that transition to unpause relayout for the transitioning
+     * task after the transition has ended.
+     *
+     * @param transition the ready transaction
+     * @param info of Transition to check if relayout needs to be paused for a task
+     * @param change a change in the given transition
+     */
+    default void onTransitionReady(IBinder transition, TransitionInfo info,
+            TransitionInfo.Change change) {}
+
+    /**
+     * Notifies that a shell transition is about to merge with another to give the window
+     * decoration a chance to prepare for this merge.
+     *
+     * @param merged the transaction being merged
+     * @param playing the transaction being merged into
+     */
+    default void onTransitionMerged(IBinder merged, IBinder playing) {}
+
+    /**
+     * Notifies that a shell transition is about to finish  to give the window decoration a chance
+     * to clean up.
+     *
+     * @param transaction
+     */
+    default void onTransitionFinished(IBinder transaction) {}
+
 }

libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/desktopmode/DesktopTasksControllerTest.kt

@@ -81,6 +81,7 @@ class DesktopTasksControllerTest : ShellTestCase() {
     @Mock lateinit var syncQueue: SyncTransactionQueue
     @Mock lateinit var rootTaskDisplayAreaOrganizer: RootTaskDisplayAreaOrganizer
     @Mock lateinit var transitions: Transitions
+    @Mock lateinit var transitionHandler: EnterDesktopTaskTransitionHandler
 
     lateinit var mockitoSession: StaticMockitoSession
     lateinit var controller: DesktopTasksController
@@ -116,6 +117,7 @@ class DesktopTasksControllerTest : ShellTestCase() {
             syncQueue,
             rootTaskDisplayAreaOrganizer,
             transitions,
+            transitionHandler,
             desktopModeTaskRepository,
             TestShellExecutor()
         )

libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/desktopmode/EnterDesktopTaskTransitionHandlerTest.java

@@ -0,0 +1,159 @@
+/*
+ * Copyright (C) 2023 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.desktopmode;
+
+import static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
+
+import static androidx.test.internal.runner.junit4.statement.UiThreadStatement.runOnUiThread;
+
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.doReturn;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+import android.annotation.NonNull;
+import android.app.ActivityManager;
+import android.app.WindowConfiguration;
+import android.graphics.Rect;
+import android.os.IBinder;
+import android.view.SurfaceControl;
+import android.view.WindowManager;
+import android.window.IWindowContainerToken;
+import android.window.TransitionInfo;
+import android.window.WindowContainerToken;
+import android.window.WindowContainerTransaction;
+
+import androidx.test.filters.SmallTest;
+
+import com.android.wm.shell.common.ShellExecutor;
+import com.android.wm.shell.transition.Transitions;
+
+import junit.framework.AssertionFailedError;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.function.Supplier;
+
+/** Tests of {@link com.android.wm.shell.desktopmode.EnterDesktopTaskTransitionHandler} */
+@SmallTest
+public class EnterDesktopTaskTransitionHandlerTest {
+
+    @Mock
+    private Transitions mTransitions;
+    @Mock
+    IBinder mToken;
+    @Mock
+    Supplier<SurfaceControl.Transaction> mTransactionFactory;
+    @Mock
+    SurfaceControl.Transaction mStartT;
+    @Mock
+    SurfaceControl.Transaction mFinishT;
+    @Mock
+    SurfaceControl.Transaction mAnimationT;
+    @Mock
+    Transitions.TransitionFinishCallback mTransitionFinishCallback;
+    @Mock
+    ShellExecutor mExecutor;
+    @Mock
+    SurfaceControl mSurfaceControl;
+
+    private EnterDesktopTaskTransitionHandler mEnterDesktopTaskTransitionHandler;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+
+        doReturn(mExecutor).when(mTransitions).getMainExecutor();
+        doReturn(mAnimationT).when(mTransactionFactory).get();
+
+        mEnterDesktopTaskTransitionHandler = new EnterDesktopTaskTransitionHandler(mTransitions,
+                mTransactionFactory);
+    }
+
+    @Test
+    public void testEnterFreeformAnimation() {
+        final int transitionType = Transitions.TRANSIT_ENTER_FREEFORM;
+        final int taskId = 1;
+        WindowContainerTransaction wct = new WindowContainerTransaction();
+        doReturn(mToken).when(mTransitions)
+                .startTransition(transitionType, wct, mEnterDesktopTaskTransitionHandler);
+        mEnterDesktopTaskTransitionHandler.startTransition(transitionType, wct);
+
+        TransitionInfo.Change change =
+                createChange(WindowManager.TRANSIT_CHANGE, taskId, WINDOWING_MODE_FREEFORM);
+        TransitionInfo info = createTransitionInfo(Transitions.TRANSIT_ENTER_FREEFORM, change);
+
+
+        assertTrue(mEnterDesktopTaskTransitionHandler
+                .startAnimation(mToken, info, mStartT, mFinishT, mTransitionFinishCallback));
+
+        verify(mStartT).setWindowCrop(mSurfaceControl, null);
+        verify(mStartT).apply();
+    }
+
+    @Test
+    public void testTransitEnterDesktopModeAnimation() throws Throwable {
+        final int transitionType = Transitions.TRANSIT_ENTER_DESKTOP_MODE;
+        final int taskId = 1;
+        WindowContainerTransaction wct = new WindowContainerTransaction();
+        doReturn(mToken).when(mTransitions)
+                .startTransition(transitionType, wct, mEnterDesktopTaskTransitionHandler);
+        mEnterDesktopTaskTransitionHandler.startTransition(transitionType, wct);
+
+        TransitionInfo.Change change =
+                createChange(WindowManager.TRANSIT_CHANGE, taskId, WINDOWING_MODE_FREEFORM);
+        change.setEndAbsBounds(new Rect(0, 0, 1, 1));
+        TransitionInfo info = createTransitionInfo(Transitions.TRANSIT_ENTER_DESKTOP_MODE, change);
+
+        runOnUiThread(() -> {
+            try {
+                assertTrue(mEnterDesktopTaskTransitionHandler
+                                .startAnimation(mToken, info, mStartT, mFinishT,
+                                        mTransitionFinishCallback));
+            } catch (Exception e) {
+                throw new AssertionFailedError(e.getMessage());
+            }
+        });
+
+        verify(mStartT).setWindowCrop(mSurfaceControl, change.getEndAbsBounds().width(),
+                change.getEndAbsBounds().height());
+        verify(mStartT).apply();
+    }
+
+    private TransitionInfo.Change createChange(@WindowManager.TransitionType int type, int taskId,
+            @WindowConfiguration.WindowingMode int windowingMode) {
+        final ActivityManager.RunningTaskInfo taskInfo = new ActivityManager.RunningTaskInfo();
+        taskInfo.taskId = taskId;
+        taskInfo.configuration.windowConfiguration.setWindowingMode(windowingMode);
+        final TransitionInfo.Change change = new TransitionInfo.Change(
+                new WindowContainerToken(mock(IWindowContainerToken.class)), mSurfaceControl);
+        change.setMode(type);
+        change.setTaskInfo(taskInfo);
+        return change;
+    }
+
+    private static TransitionInfo createTransitionInfo(
+            @WindowManager.TransitionType int type, @NonNull TransitionInfo.Change change) {
+        TransitionInfo info = new TransitionInfo(type, 0);
+        info.addChange(change);
+        return info;
+    }
+
+}

libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/windowdecor/DesktopModeWindowDecorViewModelTests.java

@@ -28,6 +28,7 @@ import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import android.app.ActivityManager;
+import android.app.WindowConfiguration;
 import android.hardware.display.DisplayManager;
 import android.hardware.display.VirtualDisplay;
 import android.hardware.input.InputManager;
@@ -60,6 +61,7 @@ import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Supplier;
 
 /** Tests of {@link DesktopModeWindowDecorViewModel} */
 @SmallTest
@@ -80,8 +82,9 @@ public class DesktopModeWindowDecorViewModelTests extends ShellTestCase {
     @Mock private DesktopTasksController mDesktopTasksController;
     @Mock private InputMonitor mInputMonitor;
     @Mock private InputManager mInputManager;
-
     @Mock private DesktopModeWindowDecorViewModel.InputMonitorFactory mMockInputMonitorFactory;
+    @Mock private Supplier<SurfaceControl.Transaction> mTransactionFactory;
+    @Mock private SurfaceControl.Transaction mTransaction;
     private final List<InputManager> mMockInputManagers = new ArrayList<>();
 
     private DesktopModeWindowDecorViewModel mDesktopModeWindowDecorViewModel;
@@ -102,12 +105,14 @@ public class DesktopModeWindowDecorViewModelTests extends ShellTestCase {
                 Optional.of(mDesktopTasksController),
                 Optional.of(mSplitScreenController),
                 mDesktopModeWindowDecorFactory,
-                mMockInputMonitorFactory
+                mMockInputMonitorFactory,
+                mTransactionFactory
             );
 
         doReturn(mDesktopModeWindowDecoration)
             .when(mDesktopModeWindowDecorFactory)
             .create(any(), any(), any(), any(), any(), any(), any(), any());
+        doReturn(mTransaction).when(mTransactionFactory).get();
 
         when(mMockInputMonitorFactory.create(any(), any())).thenReturn(mInputMonitor);
         // InputChannel cannot be mocked because it passes to InputEventReceiver.
@@ -250,7 +255,7 @@ public class DesktopModeWindowDecorViewModelTests extends ShellTestCase {
     }
 
     private static ActivityManager.RunningTaskInfo createTaskInfo(int taskId,
-            int displayId, int windowingMode) {
+            int displayId, @WindowConfiguration.WindowingMode int windowingMode) {
         ActivityManager.RunningTaskInfo taskInfo =
                  new TestRunningTaskInfoBuilder()
                 .setDisplayId(displayId)