Merge "Use boundsChangeTransaction to improve split-screen enter/exit" into rvc-dev

core/java/android/view/WindowlessWindowManager.java

@@ -209,7 +209,11 @@ public class WindowlessWindowManager implements IWindowSession {
 
     /** @hide */
     protected SurfaceControl getSurfaceControl(View rootView) {
-        final State s = mStateForWindow.get(rootView.getViewRootImpl().mWindow.asBinder());
+        final ViewRootImpl root = rootView.getViewRootImpl();
+        if (root == null) {
+            return null;
+        }
+        final State s = mStateForWindow.get(root.mWindow.asBinder());
         if (s == null) {
             return null;
         }

core/java/android/window/WindowContainerTransaction.java

@@ -264,6 +264,29 @@ public final class WindowContainerTransaction implements Parcelable {
         return this;
     }
 
+    /**
+     * Merges another WCT into this one.
+     * @param transfer When true, this will transfer everything from other potentially leaving
+     *                 other in an unusable state. When false, other is left alone, but
+     *                 SurfaceFlinger Transactions will not be merged.
+     * @hide
+     */
+    public void merge(WindowContainerTransaction other, boolean transfer) {
+        for (int i = 0, n = other.mChanges.size(); i < n; ++i) {
+            final IBinder key = other.mChanges.keyAt(i);
+            Change existing = mChanges.get(key);
+            if (existing == null) {
+                existing = new Change();
+                mChanges.put(key, existing);
+            }
+            existing.merge(other.mChanges.valueAt(i), transfer);
+        }
+        for (int i = 0, n = other.mHierarchyOps.size(); i < n; ++i) {
+            mHierarchyOps.add(transfer ? other.mHierarchyOps.get(i)
+                    : new HierarchyOp(other.mHierarchyOps.get(i)));
+        }
+    }
+
     /** @hide */
     public Map<IBinder, Change> getChanges() {
         return mChanges;
@@ -359,6 +382,41 @@ public final class WindowContainerTransaction implements Parcelable {
             mActivityWindowingMode = in.readInt();
         }
 
+        /**
+         * @param transfer When true, this will transfer other into this leaving other in an
+         *                 undefined state. Use this if you don't intend to use other. When false,
+         *                 SurfaceFlinger Transactions will not merge.
+         */
+        public void merge(Change other, boolean transfer) {
+            mConfiguration.setTo(other.mConfiguration, other.mConfigSetMask, other.mWindowSetMask);
+            mConfigSetMask |= other.mConfigSetMask;
+            mWindowSetMask |= other.mWindowSetMask;
+            if ((other.mChangeMask & CHANGE_FOCUSABLE) != 0) {
+                mFocusable = other.mFocusable;
+            }
+            if (transfer && (other.mChangeMask & CHANGE_BOUNDS_TRANSACTION) != 0) {
+                mBoundsChangeTransaction = other.mBoundsChangeTransaction;
+                other.mBoundsChangeTransaction = null;
+            }
+            if ((other.mChangeMask & CHANGE_PIP_CALLBACK) != 0) {
+                mPinnedBounds = transfer ? other.mPinnedBounds : new Rect(other.mPinnedBounds);
+            }
+            if ((other.mChangeMask & CHANGE_HIDDEN) != 0) {
+                mHidden = other.mHidden;
+            }
+            mChangeMask |= other.mChangeMask;
+            if (other.mActivityWindowingMode >= 0) {
+                mActivityWindowingMode = other.mActivityWindowingMode;
+            }
+            if (other.mWindowingMode >= 0) {
+                mWindowingMode = other.mWindowingMode;
+            }
+            if (other.mBoundsChangeSurfaceBounds != null) {
+                mBoundsChangeSurfaceBounds = transfer ? other.mBoundsChangeSurfaceBounds
+                        : new Rect(other.mBoundsChangeSurfaceBounds);
+            }
+        }
+
         public int getWindowingMode() {
             return mWindowingMode;
         }
@@ -522,6 +580,12 @@ public final class WindowContainerTransaction implements Parcelable {
             mToTop = toTop;
         }
 
+        public HierarchyOp(@NonNull HierarchyOp copy) {
+            mContainer = copy.mContainer;
+            mReparent = copy.mReparent;
+            mToTop = copy.mToTop;
+        }
+
         protected HierarchyOp(Parcel in) {
             mContainer = in.readStrongBinder();
             mReparent = in.readStrongBinder();

packages/SystemUI/src/com/android/systemui/stackdivider/Divider.java

@@ -99,16 +99,19 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
     private Handler mHandler;
     private KeyguardStateController mKeyguardStateController;
 
+    private WindowManagerProxy mWindowManagerProxy;
+
     private final ArrayList<WeakReference<Consumer<Boolean>>> mDockedStackExistsListeners =
             new ArrayList<>();
 
     private SplitScreenTaskOrganizer mSplits = new SplitScreenTaskOrganizer(this);
 
     private DisplayChangeController.OnDisplayChangingListener mRotationController =
-            (display, fromRotation, toRotation, t) -> {
-                if (!mSplits.isSplitScreenSupported()) {
+            (display, fromRotation, toRotation, wct) -> {
+                if (!mSplits.isSplitScreenSupported() || mWindowManagerProxy == null) {
                     return;
                 }
+                WindowContainerTransaction t = new WindowContainerTransaction();
                 DisplayLayout displayLayout =
                         new DisplayLayout(mDisplayController.getDisplayLayout(display));
                 SplitDisplayLayout sdl = new SplitDisplayLayout(mContext, displayLayout, mSplits);
@@ -127,6 +130,17 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
                 if (isSplitActive()) {
                     WindowManagerProxy.applyHomeTasksMinimized(sdl, mSplits.mSecondary.token, t);
                 }
+                if (mWindowManagerProxy.queueSyncTransactionIfWaiting(t)) {
+                    // Because sync transactions are serialized, its possible for an "older"
+                    // bounds-change to get applied after a screen rotation. In that case, we
+                    // want to actually defer on that rather than apply immediately. Of course,
+                    // this means that the bounds may not change until after the rotation so
+                    // the user might see some artifacts. This should be rare.
+                    Slog.w(TAG, "Screen rotated while other operations were pending, this may"
+                            + " result in some graphical artifacts.");
+                } else {
+                    wct.merge(t, true /* transfer */);
+                }
             };
 
     private final DividerImeController mImePositionProcessor;
@@ -159,6 +173,7 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
         mRecentsOptionalLazy = recentsOptionalLazy;
         mForcedResizableController = new ForcedResizableInfoActivityController(context, this);
         mTransactionPool = transactionPool;
+        mWindowManagerProxy = new WindowManagerProxy(mTransactionPool, mHandler);
         mImePositionProcessor = new DividerImeController(mSplits, mTransactionPool, mHandler);
     }
 
@@ -278,9 +293,9 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
                 LayoutInflater.from(dctx).inflate(R.layout.docked_stack_divider, null);
         DisplayLayout displayLayout = mDisplayController.getDisplayLayout(mContext.getDisplayId());
         mView.injectDependencies(mWindowManager, mDividerState, this, mSplits, mSplitLayout,
-                mImePositionProcessor);
+                mImePositionProcessor, mWindowManagerProxy);
         mView.setVisibility(mVisible ? View.VISIBLE : View.INVISIBLE);
-        mView.setMinimizedDockStack(mMinimized, mHomeStackResizable);
+        mView.setMinimizedDockStack(mMinimized, mHomeStackResizable, null /* transaction */);
         final int size = dctx.getResources().getDimensionPixelSize(
                 com.android.internal.R.dimen.docked_stack_divider_thickness);
         final boolean landscape = configuration.orientation == ORIENTATION_LANDSCAPE;
@@ -303,7 +318,7 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
         addDivider(configuration);
 
         if (mMinimized) {
-            mView.setMinimizedDockStack(true, mHomeStackResizable);
+            mView.setMinimizedDockStack(true, mHomeStackResizable, null /* transaction */);
             updateTouchable();
         }
         mView.setHidden(isDividerHidden);
@@ -327,11 +342,13 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
             if (visible) {
                 mView.enterSplitMode(mHomeStackResizable);
                 // Update state because animations won't finish.
-                mView.setMinimizedDockStack(mMinimized, mHomeStackResizable);
+                mWindowManagerProxy.runInSync(
+                        t -> mView.setMinimizedDockStack(mMinimized, mHomeStackResizable, t));
+
             } else {
                 mView.exitSplitMode();
-                // un-minimize so that next entry triggers minimize anim.
-                mView.setMinimizedDockStack(false /* minimized */, mHomeStackResizable);
+                mWindowManagerProxy.runInSync(
+                        t -> mView.setMinimizedDockStack(false, mHomeStackResizable, t));
             }
             // Notify existence listeners
             synchronized (mDockedStackExistsListeners) {
@@ -344,12 +361,6 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
         }
     }
 
-    void onSplitDismissed() {
-        updateVisibility(false /* visible */);
-        mMinimized = false;
-        removeDivider();
-    }
-
     /** Switch to minimized state if appropriate */
     public void setMinimized(final boolean minimized) {
         if (DEBUG) Slog.d(TAG, "posting ext setMinimized " + minimized + " vis:" + mVisible);
@@ -405,7 +416,7 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
             }
         }
         updateTouchable();
-        WindowOrganizer.applyTransaction(wct);
+        mWindowManagerProxy.applySyncTransaction(wct);
     }
 
     void setAdjustedForIme(boolean adjustedForIme) {
@@ -501,7 +512,14 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
         update(mDisplayController.getDisplayContext(
                 mContext.getDisplayId()).getResources().getConfiguration());
         // Set resizable directly here because applyEnterSplit already resizes home stack.
-        mHomeStackResizable = WindowManagerProxy.applyEnterSplit(mSplits, mSplitLayout);
+        mHomeStackResizable = mWindowManagerProxy.applyEnterSplit(mSplits, mSplitLayout);
+    }
+
+    void startDismissSplit() {
+        mWindowManagerProxy.applyDismissSplit(mSplits, mSplitLayout, true /* dismissOrMaximize */);
+        updateVisibility(false /* visible */);
+        mMinimized = false;
+        removeDivider();
     }
 
     void ensureMinimizedSplit() {
@@ -530,6 +548,10 @@ public class Divider extends SystemUI implements DividerView.DividerCallbacks,
         return mSplitLayout;
     }
 
+    WindowManagerProxy getWmProxy() {
+        return mWindowManagerProxy;
+    }
+
     /** @return the container token for the secondary split root task. */
     public WindowContainerToken getSecondaryRoot() {
         if (mSplits == null || mSplits.mSecondary == null) {

packages/SystemUI/src/com/android/systemui/stackdivider/DividerImeController.java

@@ -29,7 +29,6 @@ import android.view.SurfaceControl;
 import android.window.TaskOrganizer;
 import android.window.WindowContainerToken;
 import android.window.WindowContainerTransaction;
-import android.window.WindowOrganizer;
 
 import androidx.annotation.Nullable;
 
@@ -213,7 +212,7 @@ class DividerImeController implements DisplayImeController.ImePositionProcessor
                     SCREEN_WIDTH_DP_UNDEFINED, SCREEN_HEIGHT_DP_UNDEFINED);
         }
 
-        WindowOrganizer.applyTransaction(wct);
+        mSplits.mDivider.getWmProxy().applySyncTransaction(wct);
 
         // Update all the adjusted-for-ime states
         if (!mPaused) {

packages/SystemUI/src/com/android/systemui/stackdivider/DividerView.java

@@ -46,6 +46,7 @@ import android.view.VelocityTracker;
 import android.view.View;
 import android.view.View.OnTouchListener;
 import android.view.ViewConfiguration;
+import android.view.ViewRootImpl;
 import android.view.ViewTreeObserver.InternalInsetsInfo;
 import android.view.ViewTreeObserver.OnComputeInternalInsetsListener;
 import android.view.WindowManager;
@@ -138,7 +139,7 @@ public class DividerView extends FrameLayout implements OnTouchListener,
     private final Rect mOtherInsetRect = new Rect();
     private final Rect mLastResizeRect = new Rect();
     private final Rect mTmpRect = new Rect();
-    private final WindowManagerProxy mWindowManagerProxy = WindowManagerProxy.getInstance();
+    private WindowManagerProxy mWindowManagerProxy;
     private DividerWindowManager mWindowManager;
     private VelocityTracker mVelocityTracker;
     private FlingAnimationUtils mFlingAnimationUtils;
@@ -360,13 +361,14 @@ public class DividerView extends FrameLayout implements OnTouchListener,
 
     public void injectDependencies(DividerWindowManager windowManager, DividerState dividerState,
             DividerCallbacks callback, SplitScreenTaskOrganizer tiles, SplitDisplayLayout sdl,
-            DividerImeController imeController) {
+            DividerImeController imeController, WindowManagerProxy wmProxy) {
         mWindowManager = windowManager;
         mState = dividerState;
         mCallback = callback;
         mTiles = tiles;
         mSplitLayout = sdl;
         mImeController = imeController;
+        mWindowManagerProxy = wmProxy;
 
         if (mState.mRatioPositionBeforeMinimized == 0) {
             // Set the middle target as the initial state
@@ -376,10 +378,6 @@ public class DividerView extends FrameLayout implements OnTouchListener,
         }
     }
 
-    public WindowManagerProxy getWindowManagerProxy() {
-        return mWindowManagerProxy;
-    }
-
     public Rect getNonMinimizedSplitScreenSecondaryBounds() {
         mOtherTaskRect.set(mSplitLayout.mSecondary);
         return mOtherTaskRect;
@@ -519,7 +517,8 @@ public class DividerView extends FrameLayout implements OnTouchListener,
                 if (mMoving && mDockSide != WindowManager.DOCKED_INVALID) {
                     SnapTarget snapTarget = getSnapAlgorithm().calculateSnapTarget(
                             mStartPosition, 0 /* velocity */, false /* hardDismiss */);
-                    resizeStackSurfaces(calculatePosition(x, y), mStartPosition, snapTarget);
+                    resizeStackSurfaces(calculatePosition(x, y), mStartPosition, snapTarget,
+                            null /* transaction */);
                 }
                 break;
             case MotionEvent.ACTION_UP:
@@ -608,7 +607,7 @@ public class DividerView extends FrameLayout implements OnTouchListener,
                 taskPositionSameAtEnd && animation.getAnimatedFraction() == 1f
                         ? TASK_POSITION_SAME
                         : snapTarget.taskPosition,
-                snapTarget));
+                snapTarget, null /* transaction */));
         Consumer<Boolean> endAction = cancelled -> {
             if (DEBUG) Slog.d(TAG, "End Fling " + cancelled + " min:" + mIsInMinimizeInteraction);
             final boolean wasMinimizeInteraction = mIsInMinimizeInteraction;
@@ -716,7 +715,7 @@ public class DividerView extends FrameLayout implements OnTouchListener,
             dismissOrMaximize = mDockSide == WindowManager.DOCKED_RIGHT
                     || mDockSide == WindowManager.DOCKED_BOTTOM;
         }
-        mWindowManagerProxy.dismissOrMaximizeDocked(mTiles, dismissOrMaximize);
+        mWindowManagerProxy.dismissOrMaximizeDocked(mTiles, mSplitLayout, dismissOrMaximize);
         Transaction t = mTiles.getTransaction();
         setResizeDimLayer(t, true /* primary */, 0f);
         setResizeDimLayer(t, false /* primary */, 0f);
@@ -806,7 +805,8 @@ public class DividerView extends FrameLayout implements OnTouchListener,
         mWindowManager.setTouchRegion(touchRegion);
     }
 
-    public void setMinimizedDockStack(boolean minimized, boolean isHomeStackResizable) {
+    void setMinimizedDockStack(boolean minimized, boolean isHomeStackResizable,
+            Transaction t) {
         mHomeStackResizable = isHomeStackResizable;
         updateDockSide();
         if (!minimized) {
@@ -840,9 +840,10 @@ public class DividerView extends FrameLayout implements OnTouchListener,
                     // Relayout to recalculate the divider shadow when minimizing
                     requestLayout();
                     mIsInMinimizeInteraction = true;
-                    resizeStackSurfaces(mSplitLayout.getMinimizedSnapAlgorithm().getMiddleTarget());
+                    resizeStackSurfaces(
+                            mSplitLayout.getMinimizedSnapAlgorithm().getMiddleTarget(), t);
                 } else {
-                    resizeStackSurfaces(mSnapTargetBeforeMinimized);
+                    resizeStackSurfaces(mSnapTargetBeforeMinimized, t);
                     mIsInMinimizeInteraction = false;
                 }
             }
@@ -873,10 +874,11 @@ public class DividerView extends FrameLayout implements OnTouchListener,
      * assigned to it.
      */
     private SurfaceControl getWindowSurfaceControl() {
-        if (getViewRootImpl() == null) {
+        final ViewRootImpl root = getViewRootImpl();
+        if (root == null) {
             return null;
         }
-        SurfaceControl out = getViewRootImpl().getSurfaceControl();
+        SurfaceControl out = root.getSurfaceControl();
         if (out != null && out.isValid()) {
             return out;
         }
@@ -885,15 +887,13 @@ public class DividerView extends FrameLayout implements OnTouchListener,
 
     void exitSplitMode() {
         // Reset tile bounds
-        post(() -> {
-            final SurfaceControl sc = getWindowSurfaceControl();
-            if (sc == null) {
-                return;
-            }
-            Transaction t = mTiles.getTransaction();
-            t.hide(sc).apply();
-            mTiles.releaseTransaction(t);
-        });
+        final SurfaceControl sc = getWindowSurfaceControl();
+        if (sc == null) {
+            return;
+        }
+        Transaction t = mTiles.getTransaction();
+        t.hide(sc).apply();
+        mTiles.releaseTransaction(t);
         int midPos = mSplitLayout.getSnapAlgorithm().getMiddleTarget().position;
         WindowManagerProxy.applyResizeSplits(midPos, mSplitLayout);
     }
@@ -1049,8 +1049,8 @@ public class DividerView extends FrameLayout implements OnTouchListener,
                 mDividerSize);
     }
 
-    private void resizeStackSurfaces(SnapTarget taskSnapTarget) {
-        resizeStackSurfaces(taskSnapTarget.position, taskSnapTarget.position, taskSnapTarget);
+    private void resizeStackSurfaces(SnapTarget taskSnapTarget, Transaction t) {
+        resizeStackSurfaces(taskSnapTarget.position, taskSnapTarget.position, taskSnapTarget, t);
     }
 
     void resizeSplitSurfaces(Transaction t, Rect dockedRect, Rect otherRect) {
@@ -1105,7 +1105,8 @@ public class DividerView extends FrameLayout implements OnTouchListener,
         }
     }
 
-    void resizeStackSurfaces(int position, int taskPosition, SnapTarget taskSnapTarget) {
+    void resizeStackSurfaces(int position, int taskPosition, SnapTarget taskSnapTarget,
+            Transaction transaction) {
         if (mRemoved) {
             // This divider view has been removed so shouldn't have any additional influence.
             return;
@@ -1123,7 +1124,8 @@ public class DividerView extends FrameLayout implements OnTouchListener,
             mBackground.invalidate();
         }
 
-        Transaction t = mTiles.getTransaction();
+        final boolean ownTransaction = transaction == null;
+        final Transaction t = ownTransaction ? mTiles.getTransaction() : transaction;
         mLastResizeRect.set(mDockedRect);
         if (mHomeStackResizable && mIsInMinimizeInteraction) {
             calculateBoundsForPosition(mSnapTargetBeforeMinimized.position, mDockSide,
@@ -1138,8 +1140,10 @@ public class DividerView extends FrameLayout implements OnTouchListener,
             }
             resizeSplitSurfaces(t, mDockedRect, mDockedTaskRect, mOtherRect,
                     mOtherTaskRect);
-            t.apply();
-            mTiles.releaseTransaction(t);
+            if (ownTransaction) {
+                t.apply();
+                mTiles.releaseTransaction(t);
+            }
             return;
         }
 
@@ -1201,8 +1205,10 @@ public class DividerView extends FrameLayout implements OnTouchListener,
         SnapTarget closestDismissTarget = getSnapAlgorithm().getClosestDismissTarget(position);
         float dimFraction = getDimFraction(position, closestDismissTarget);
         setResizeDimLayer(t, isDismissTargetPrimary(closestDismissTarget), dimFraction);
-        t.apply();
-        mTiles.releaseTransaction(t);
+        if (ownTransaction) {
+            t.apply();
+            mTiles.releaseTransaction(t);
+        }
     }
 
     private void applyExitAnimationParallax(Rect taskRect, int position) {
@@ -1383,7 +1389,8 @@ public class DividerView extends FrameLayout implements OnTouchListener,
 
         resizeStackSurfaces(calculatePositionForInsetBounds(),
                 mSplitLayout.getSnapAlgorithm().getMiddleTarget().position,
-                mSplitLayout.getSnapAlgorithm().getMiddleTarget());
+                mSplitLayout.getSnapAlgorithm().getMiddleTarget(),
+                null /* transaction */);
     }
 
     void onRecentsDrawn() {

packages/SystemUI/src/com/android/systemui/stackdivider/SplitScreenTaskOrganizer.java

@@ -200,8 +200,7 @@ class SplitScreenTaskOrganizer extends TaskOrganizer {
                     Log.d(TAG, "    was in split, so this means leave it "
                             + mPrimary.topActivityType + "  " + mSecondary.topActivityType);
                 }
-                WindowManagerProxy.applyDismissSplit(this, true /* dismissOrMaximize */);
-                mDivider.onSplitDismissed();
+                mDivider.startDismissSplit();
             } else if (!primaryIsEmpty && primaryWasEmpty && secondaryWasEmpty) {
                 // Wasn't in split-mode (both were empty), but now that the primary split is
                 // populated, we should fully enter split by moving everything else into secondary.

packages/SystemUI/src/com/android/systemui/stackdivider/SyncTransactionQueue.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright (C) 2020 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.systemui.stackdivider;
+
+import android.os.Handler;
+import android.util.Slog;
+import android.view.SurfaceControl;
+import android.window.WindowContainerTransaction;
+import android.window.WindowContainerTransactionCallback;
+import android.window.WindowOrganizer;
+
+import androidx.annotation.NonNull;
+
+import com.android.systemui.TransactionPool;
+
+import java.util.ArrayList;
+
+/**
+ * Helper for serializing sync-transactions and corresponding callbacks.
+ */
+class SyncTransactionQueue {
+    private static final boolean DEBUG = Divider.DEBUG;
+    private static final String TAG = "SyncTransactionQueue";
+
+    // Just a little longer than the sync-engine timeout of 5s
+    private static final int REPLY_TIMEOUT = 5300;
+
+    private final TransactionPool mTransactionPool;
+    private final Handler mHandler;
+
+    // Sync Transactions currently don't support nesting or interleaving properly, so
+    // queue up transactions to run them serially.
+    private final ArrayList<SyncCallback> mQueue = new ArrayList<>();
+
+    private SyncCallback mInFlight = null;
+    private final ArrayList<TransactionRunnable> mRunnables = new ArrayList<>();
+
+    private final Runnable mOnReplyTimeout = () -> {
+        synchronized (mQueue) {
+            if (mInFlight != null && mQueue.contains(mInFlight)) {
+                Slog.w(TAG, "Sync Transaction timed-out: " + mInFlight.mWCT);
+                mInFlight.onTransactionReady(mInFlight.mId, new SurfaceControl.Transaction());
+            }
+        }
+    };
+
+    SyncTransactionQueue(TransactionPool pool, Handler handler) {
+        mTransactionPool = pool;
+        mHandler = handler;
+    }
+
+    /**
+     * Queues a sync transaction to be sent serially to WM.
+     */
+    void queue(WindowContainerTransaction wct) {
+        SyncCallback cb = new SyncCallback(wct);
+        synchronized (mQueue) {
+            if (DEBUG) Slog.d(TAG, "Queueing up " + wct);
+            mQueue.add(cb);
+            if (mQueue.size() == 1) {
+                cb.send();
+            }
+        }
+    }
+
+    /**
+     * Queues a sync transaction only if there are already sync transaction(s) queued or in flight.
+     * Otherwise just returns without queueing.
+     * @return {@code true} if queued, {@code false} if not.
+     */
+    boolean queueIfWaiting(WindowContainerTransaction wct) {
+        synchronized (mQueue) {
+            if (mQueue.isEmpty()) {
+                if (DEBUG) Slog.d(TAG, "Nothing in queue, so skip queueing up " + wct);
+                return false;
+            }
+            if (DEBUG) Slog.d(TAG, "Queue is non-empty, so queueing up " + wct);
+            SyncCallback cb = new SyncCallback(wct);
+            mQueue.add(cb);
+            if (mQueue.size() == 1) {
+                cb.send();
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Runs a runnable in sync with sync transactions (ie. when the current in-flight transaction
+     * returns. If there are no transactions in-flight, runnable executes immediately.
+     */
+    void runInSync(TransactionRunnable runnable) {
+        synchronized (mQueue) {
+            if (DEBUG) Slog.d(TAG, "Run in sync. mInFlight=" + mInFlight);
+            if (mInFlight != null) {
+                mRunnables.add(runnable);
+                return;
+            }
+        }
+        SurfaceControl.Transaction t = mTransactionPool.acquire();
+        runnable.runWithTransaction(t);
+        t.apply();
+        mTransactionPool.release(t);
+    }
+
+    // Synchronized on mQueue
+    private void onTransactionReceived(@NonNull SurfaceControl.Transaction t) {
+        if (DEBUG) Slog.d(TAG, "  Running " + mRunnables.size() + " sync runnables");
+        for (int i = 0, n = mRunnables.size(); i < n; ++i) {
+            mRunnables.get(i).runWithTransaction(t);
+        }
+        mRunnables.clear();
+        t.apply();
+        t.close();
+    }
+
+    interface TransactionRunnable {
+        void runWithTransaction(SurfaceControl.Transaction t);
+    }
+
+    private class SyncCallback extends WindowContainerTransactionCallback {
+        int mId = -1;
+        final WindowContainerTransaction mWCT;
+
+        SyncCallback(WindowContainerTransaction wct) {
+            mWCT = wct;
+        }
+
+        // Must be sychronized on mQueue
+        void send() {
+            if (mInFlight != null) {
+                throw new IllegalStateException("Sync Transactions must be serialized. In Flight: "
+                        + mInFlight.mId + " - " + mInFlight.mWCT);
+            }
+            mInFlight = this;
+            if (DEBUG) Slog.d(TAG, "Sending sync transaction: " + mWCT);
+            mId = new WindowOrganizer().applySyncTransaction(mWCT, this);
+            if (DEBUG) Slog.d(TAG, " Sent sync transaction. Got id=" + mId);
+            mHandler.postDelayed(mOnReplyTimeout, REPLY_TIMEOUT);
+        }
+
+        @Override
+        public void onTransactionReady(int id,
+                @androidx.annotation.NonNull SurfaceControl.Transaction t) {
+            mHandler.post(() -> {
+                synchronized (mQueue) {
+                    if (mId != id) {
+                        Slog.e(TAG, "Got an unexpected onTransactionReady. Expected "
+                                + mId + " but got " + id);
+                        return;
+                    }
+                    mInFlight = null;
+                    mHandler.removeCallbacks(mOnReplyTimeout);
+                    if (DEBUG) Slog.d(TAG, "onTransactionReady id=" + mId);
+                    mQueue.remove(this);
+                    onTransactionReceived(t);
+                    if (!mQueue.isEmpty()) {
+                        mQueue.get(0).send();
+                    }
+                }
+            });
+        }
+    }
+}

packages/SystemUI/src/com/android/systemui/stackdivider/WindowManagerProxy.java

@@ -25,9 +25,11 @@ import android.annotation.NonNull;
 import android.app.ActivityManager;
 import android.app.ActivityTaskManager;
 import android.graphics.Rect;
+import android.os.Handler;
 import android.os.RemoteException;
 import android.util.Log;
 import android.view.Display;
+import android.view.SurfaceControl;
 import android.view.WindowManagerGlobal;
 import android.window.TaskOrganizer;
 import android.window.WindowContainerToken;
@@ -35,6 +37,7 @@ import android.window.WindowContainerTransaction;
 import android.window.WindowOrganizer;
 
 import com.android.internal.annotations.GuardedBy;
+import com.android.systemui.TransactionPool;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -49,8 +52,6 @@ public class WindowManagerProxy {
     private static final String TAG = "WindowManagerProxy";
     private static final int[] HOME_AND_RECENTS = {ACTIVITY_TYPE_HOME, ACTIVITY_TYPE_RECENTS};
 
-    private static final WindowManagerProxy sInstance = new WindowManagerProxy();
-
     @GuardedBy("mDockedRect")
     private final Rect mDockedRect = new Rect();
 
@@ -61,6 +62,8 @@ public class WindowManagerProxy {
 
     private final ExecutorService mExecutor = Executors.newSingleThreadExecutor();
 
+    private final SyncTransactionQueue mSyncTransactionQueue;
+
     private final Runnable mSetTouchableRegionRunnable = new Runnable() {
         @Override
         public void run() {
@@ -76,16 +79,13 @@ public class WindowManagerProxy {
         }
     };
 
-    private WindowManagerProxy() {
+    WindowManagerProxy(TransactionPool transactionPool, Handler handler) {
+        mSyncTransactionQueue = new SyncTransactionQueue(transactionPool, handler);
     }
 
-    public static WindowManagerProxy getInstance() {
-        return sInstance;
-    }
-
-    void dismissOrMaximizeDocked(
-            final SplitScreenTaskOrganizer tiles, final boolean dismissOrMaximize) {
-        mExecutor.execute(() -> applyDismissSplit(tiles, dismissOrMaximize));
+    void dismissOrMaximizeDocked(final SplitScreenTaskOrganizer tiles, SplitDisplayLayout layout,
+            final boolean dismissOrMaximize) {
+        mExecutor.execute(() -> applyDismissSplit(tiles, layout, dismissOrMaximize));
     }
 
     public void setResizing(final boolean resizing) {
@@ -163,7 +163,7 @@ public class WindowManagerProxy {
      *
      * @return whether the home stack is resizable
      */
-    static boolean applyEnterSplit(SplitScreenTaskOrganizer tiles, SplitDisplayLayout layout) {
+    boolean applyEnterSplit(SplitScreenTaskOrganizer tiles, SplitDisplayLayout layout) {
         // Set launchtile first so that any stack created after
         // getAllStackInfos and before reparent (even if unlikely) are placed
         // correctly.
@@ -174,6 +174,8 @@ public class WindowManagerProxy {
         if (rootTasks.isEmpty()) {
             return false;
         }
+        ActivityManager.RunningTaskInfo topHomeTask = null;
+        boolean homeIsTop = false;
         for (int i = rootTasks.size() - 1; i >= 0; --i) {
             final ActivityManager.RunningTaskInfo rootTask = rootTasks.get(i);
             // Only move resizeable task to split secondary. WM will just ignore this anyways...
@@ -183,16 +185,25 @@ public class WindowManagerProxy {
                     != WINDOWING_MODE_FULLSCREEN) {
                 continue;
             }
+            // Since this iterates from bottom to top, update topHomeTask for every fullscreen task
+            // so it will be left with the status of the top one.
+            topHomeTask = isHomeOrRecentTask(rootTask) ? rootTask : null;
             wct.reparent(rootTask.token, tiles.mSecondary.token, true /* onTop */);
         }
         // Move the secondary split-forward.
         wct.reorder(tiles.mSecondary.token, true /* onTop */);
         boolean isHomeResizable = applyHomeTasksMinimized(layout, null /* parent */, wct);
-        WindowOrganizer.applyTransaction(wct);
+        if (isHomeResizable && topHomeTask != null) {
+            // Translate/update-crop of secondary out-of-band with sync transaction -- Until BALST
+            // is enabled, this temporarily syncs the home surface position with offset until
+            // sync transaction finishes.
+            wct.setBoundsChangeTransaction(topHomeTask.token, tiles.mHomeBounds);
+        }
+        applySyncTransaction(wct);
         return isHomeResizable;
     }
 
-    private static boolean isHomeOrRecentTask(ActivityManager.RunningTaskInfo ti) {
+    static boolean isHomeOrRecentTask(ActivityManager.RunningTaskInfo ti) {
         final int atype = ti.configuration.windowConfiguration.getActivityType();
         return atype == ACTIVITY_TYPE_HOME || atype == ACTIVITY_TYPE_RECENTS;
     }
@@ -203,7 +214,8 @@ public class WindowManagerProxy {
      *                          split (thus resulting in the top of the secondary split becoming
      *                          fullscreen. {@code false} resolves the other way.
      */
-    static void applyDismissSplit(SplitScreenTaskOrganizer tiles, boolean dismissOrMaximize) {
+    void applyDismissSplit(SplitScreenTaskOrganizer tiles, SplitDisplayLayout layout,
+            boolean dismissOrMaximize) {
         // Set launch root first so that any task created after getChildContainers and
         // before reparent (pretty unlikely) are put into fullscreen.
         TaskOrganizer.setLaunchRoot(Display.DEFAULT_DISPLAY, null);
@@ -229,6 +241,7 @@ public class WindowManagerProxy {
                 wct.reparent(primaryChildren.get(i).token, null /* parent */,
                         true /* onTop */);
             }
+            boolean homeOnTop = false;
             // Don't need to worry about home tasks because they are already in the "proper"
             // order within the secondary split.
             for (int i = secondaryChildren.size() - 1; i >= 0; --i) {
@@ -236,8 +249,31 @@ public class WindowManagerProxy {
                 wct.reparent(ti.token, null /* parent */, true /* onTop */);
                 if (isHomeOrRecentTask(ti)) {
                     wct.setBounds(ti.token, null);
+                    if (i == 0) {
+                        homeOnTop = true;
+                    }
                 }
             }
+            if (homeOnTop) {
+                // Translate/update-crop of secondary out-of-band with sync transaction -- instead
+                // play this in sync with new home-app frame because until BALST is enabled this
+                // shows up on screen before the syncTransaction returns.
+                // We only have access to the secondary root surface, though, so in order to
+                // position things properly, we have to take into account the existing negative
+                // offset/crop of the minimized-home task.
+                final boolean landscape = layout.mDisplayLayout.isLandscape();
+                final int posX = landscape ? layout.mSecondary.left - tiles.mHomeBounds.left
+                        : layout.mSecondary.left;
+                final int posY = landscape ? layout.mSecondary.top
+                        : layout.mSecondary.top - tiles.mHomeBounds.top;
+                final SurfaceControl.Transaction sft = new SurfaceControl.Transaction();
+                sft.setPosition(tiles.mSecondarySurface, posX, posY);
+                final Rect crop = new Rect(0, 0, layout.mDisplayLayout.width(),
+                        layout.mDisplayLayout.height());
+                crop.offset(-posX, -posY);
+                sft.setWindowCrop(tiles.mSecondarySurface, crop);
+                wct.setBoundsChangeTransaction(tiles.mSecondary.token, sft);
+            }
         } else {
             // Maximize, so move non-home secondary split first
             for (int i = secondaryChildren.size() - 1; i >= 0; --i) {
@@ -267,6 +303,29 @@ public class WindowManagerProxy {
         }
         // Reset focusable to true
         wct.setFocusable(tiles.mPrimary.token, true /* focusable */);
-        WindowOrganizer.applyTransaction(wct);
+        applySyncTransaction(wct);
+    }
+
+    /**
+     * Utility to apply a sync transaction serially with other sync transactions.
+     *
+     * @see SyncTransactionQueue#queue
+     */
+    void applySyncTransaction(WindowContainerTransaction wct) {
+        mSyncTransactionQueue.queue(wct);
+    }
+
+    /**
+     * @see SyncTransactionQueue#queueIfWaiting
+     */
+    boolean queueSyncTransactionIfWaiting(WindowContainerTransaction wct) {
+        return mSyncTransactionQueue.queueIfWaiting(wct);
+    }
+
+    /**
+     * @see SyncTransactionQueue#runInSync
+     */
+    void runInSync(SyncTransactionQueue.TransactionRunnable runnable) {
+        mSyncTransactionQueue.runInSync(runnable);
     }
 }

services/core/java/com/android/server/wm/WindowState.java

@@ -21,6 +21,7 @@ import static android.app.AppOpsManager.MODE_ALLOWED;
 import static android.app.AppOpsManager.MODE_DEFAULT;
 import static android.app.AppOpsManager.OP_NONE;
 import static android.app.WindowConfiguration.ACTIVITY_TYPE_DREAM;
+import static android.app.WindowConfiguration.ACTIVITY_TYPE_HOME;
 import static android.app.WindowConfiguration.isSplitScreenWindowingMode;
 import static android.content.res.Configuration.ORIENTATION_LANDSCAPE;
 import static android.os.PowerManager.DRAW_WAKE_LOCK;
@@ -3757,6 +3758,12 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
         if (!inSplitScreenWindowingMode() && !inFreeformWindowingMode()) {
             return false;
         }
+        // TODO(157912944): formalize drag-resizing so that exceptions aren't hardcoded like this
+        if (task.getActivityType() == ACTIVITY_TYPE_HOME) {
+            // The current sys-ui implementations never live-resize home, so to prevent WSA from
+            // creating/destroying surfaces (which messes up sync-transactions), skip HOME tasks.
+            return false;
+        }
         if (mAttrs.width != MATCH_PARENT || mAttrs.height != MATCH_PARENT) {
             // Floating windows never enter drag resize mode.
             return false;