From 3c2f615fb79094457abd5615800e1e3e95018c98 Mon Sep 17 00:00:00 2001
From: Luca Zuccarini <acul@google.com>
Date: Mon, 18 Nov 2024 15:06:46 +0000
Subject: Animation takeovers in Predictive Back.

Bug: 323863002
Flag: com.android.systemui.shared.return_animation_framework_library
Flag: com.android.systemui.shared.return_animation_framework_long_lived
Test: atest BackAnimationControllerTest

Change-Id: Ide64132bc2856c88893e50d148fa4850b5575114
---
 .../window/IBackAnimationHandoffHandler.aidl       | 40 +++++++++
 .../android/window/IOnBackInvokedCallback.aidl     |  6 ++
 .../android/window/ImeOnBackInvokedDispatcher.java |  5 ++
 .../window/WindowOnBackInvokedDispatcher.java      |  5 ++
 .../wm/shell/back/BackAnimationController.java     | 99 ++++++++++++++++++++--
 .../wm/shell/back/BackAnimationControllerTest.java | 53 ++++++++++++
 .../server/wm/BackNavigationControllerTests.java   |  5 ++
 7 files changed, 208 insertions(+), 5 deletions(-)
 create mode 100644 core/java/android/window/IBackAnimationHandoffHandler.aidl

diff --git a/core/java/android/window/IBackAnimationHandoffHandler.aidl b/core/java/android/window/IBackAnimationHandoffHandler.aidl
new file mode 100644
index 000000000000..577948dd0abc
--- /dev/null
+++ b/core/java/android/window/IBackAnimationHandoffHandler.aidl
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2024 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 android.window;
+
+import android.os.Bundle;
+import android.view.RemoteAnimationTarget;
+import android.window.BackMotionEvent;
+import android.window.WindowAnimationState;
+
+
+/**
+ * Interface that allows an {@link OnBackInvokedCallback} object to hand off an animation to another
+ * handler.
+ *
+ * @hide
+ */
+oneway interface IBackAnimationHandoffHandler {
+    /**
+     * Triggers a handoff of the animation of the given targets and their associated states.
+     * Important: since this is a one-way method, the caller must first make sure that the animation
+     * can indeed be taken over.
+     */
+    oneway void handOffAnimation(in RemoteAnimationTarget[] targets,
+                    in WindowAnimationState[] states);
+}
diff --git a/core/java/android/window/IOnBackInvokedCallback.aidl b/core/java/android/window/IOnBackInvokedCallback.aidl
index e07d4a9fc61b..81ad4b7bd19e 100644
--- a/core/java/android/window/IOnBackInvokedCallback.aidl
+++ b/core/java/android/window/IOnBackInvokedCallback.aidl
@@ -18,6 +18,7 @@
 package android.window;
 
 import android.window.BackMotionEvent;
+import android.window.IBackAnimationHandoffHandler;
 
 /**
  * Interface that wraps a {@link OnBackInvokedCallback} object, to be stored in window manager
@@ -61,4 +62,9 @@ oneway interface IOnBackInvokedCallback {
      * Sets whether the back gesture is past the trigger threshold.
      */
     void setTriggerBack(in boolean triggerBack);
+
+   /**
+    * Sets a {@link IBackAnimationHandoffHandler} that can be used to hand off the back animation.
+    */
+    void setHandoffHandler(in IBackAnimationHandoffHandler handoffHandler);
 }
diff --git a/core/java/android/window/ImeOnBackInvokedDispatcher.java b/core/java/android/window/ImeOnBackInvokedDispatcher.java
index c67b9cac250b..d478108d928a 100644
--- a/core/java/android/window/ImeOnBackInvokedDispatcher.java
+++ b/core/java/android/window/ImeOnBackInvokedDispatcher.java
@@ -392,6 +392,11 @@ public class ImeOnBackInvokedDispatcher implements OnBackInvokedDispatcher, Parc
             // no-op
         }
 
+        @Override
+        public void setHandoffHandler(IBackAnimationHandoffHandler handoffHandler) {
+            // no-op
+        }
+
         private void maybeRunOnAnimationCallback(Consumer<OnBackAnimationCallback> block) {
             if (mCallback instanceof OnBackAnimationCallback) {
                 mHandler.post(() -> block.accept((OnBackAnimationCallback) mCallback));
diff --git a/core/java/android/window/WindowOnBackInvokedDispatcher.java b/core/java/android/window/WindowOnBackInvokedDispatcher.java
index 0ea4bb41d3a4..20e3f6b93bd0 100644
--- a/core/java/android/window/WindowOnBackInvokedDispatcher.java
+++ b/core/java/android/window/WindowOnBackInvokedDispatcher.java
@@ -545,6 +545,11 @@ public class WindowOnBackInvokedDispatcher implements OnBackInvokedDispatcher {
             });
         }
 
+        @Override
+        public void setHandoffHandler(IBackAnimationHandoffHandler handoffHandler) {
+            // no-op
+        }
+
         @Override
         public void onBackProgressed(BackMotionEvent backEvent) {
             // This is only called in some special cases such as when activity embedding is active
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/back/BackAnimationController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/back/BackAnimationController.java
index ce7a97703f44..e9cfd9bc2209 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/back/BackAnimationController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/back/BackAnimationController.java
@@ -37,6 +37,7 @@ import static com.android.wm.shell.shared.ShellSharedConstants.KEY_EXTRA_SHELL_B
 import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.annotation.SuppressLint;
+import android.app.ActivityManager;
 import android.app.ActivityTaskManager;
 import android.app.IActivityTaskManager;
 import android.app.TaskInfo;
@@ -73,10 +74,12 @@ import android.window.BackMotionEvent;
 import android.window.BackNavigationInfo;
 import android.window.BackTouchTracker;
 import android.window.IBackAnimationFinishedCallback;
+import android.window.IBackAnimationHandoffHandler;
 import android.window.IBackAnimationRunner;
 import android.window.IOnBackInvokedCallback;
 import android.window.TransitionInfo;
 import android.window.TransitionRequestInfo;
+import android.window.WindowAnimationState;
 import android.window.WindowContainerToken;
 import android.window.WindowContainerTransaction;
 
@@ -84,6 +87,8 @@ import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.protolog.ProtoLog;
 import com.android.internal.util.LatencyTracker;
 import com.android.internal.view.AppearanceRegion;
+import com.android.systemui.animation.TransitionAnimator;
+import com.android.window.flags.Flags;
 import com.android.wm.shell.R;
 import com.android.wm.shell.common.ExternalInterfaceBinder;
 import com.android.wm.shell.common.RemoteCallable;
@@ -227,6 +232,15 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
     private Runnable mPilferPointerCallback;
     private BackAnimation.TopUiRequest mRequestTopUiCallback;
 
+    private final IBackAnimationHandoffHandler mHandoffHandler =
+            new IBackAnimationHandoffHandler.Stub() {
+                @Override
+                public void handOffAnimation(
+                        RemoteAnimationTarget[] targets, WindowAnimationState[] states) {
+                    mBackTransitionHandler.handOffAnimation(targets, states);
+                }
+            };
+
     public BackAnimationController(
             @NonNull ShellInit shellInit,
             @NonNull ShellController shellController,
@@ -282,7 +296,7 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
         mShellCommandHandler = shellCommandHandler;
         mWindowManager = context.getSystemService(WindowManager.class);
         mTransitions = transitions;
-        mBackTransitionHandler = new BackTransitionHandler();
+        mBackTransitionHandler = new BackTransitionHandler(mTransitions);
         mTransitions.addHandler(mBackTransitionHandler);
         mHandler = handler;
         mTransitions.registerObserver(mBackTransitionObserver);
@@ -715,6 +729,9 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
         }
         try {
             callback.onBackStarted(backEvent);
+            if (mBackTransitionHandler.canHandOffAnimation()) {
+                callback.setHandoffHandler(mHandoffHandler);
+            }
             mOnBackStartDispatched = true;
         } catch (RemoteException e) {
             Log.e(TAG, "dispatchOnBackStarted error: ", e);
@@ -1192,6 +1209,7 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
     }
 
     class BackTransitionHandler implements Transitions.TransitionHandler {
+        private final Transitions mTransitions;
 
         Runnable mOnAnimationFinishCallback;
         boolean mCloseTransitionRequested;
@@ -1203,6 +1221,12 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
         // animation is canceled, start a close prepare transition to finish the whole transition.
         IBinder mClosePrepareTransition;
         TransitionInfo mOpenTransitionInfo;
+        Transitions.TransitionHandler mTakeoverHandler;
+
+        BackTransitionHandler(Transitions transitions) {
+            mTransitions = transitions;
+        }
+
         void onAnimationFinished() {
             if (!mCloseTransitionRequested && mPrepareOpenTransition != null) {
                 createClosePrepareTransition();
@@ -1214,18 +1238,23 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
         }
 
         private void applyFinishOpenTransition() {
-            mOpenTransitionInfo = null;
-            mPrepareOpenTransition = null;
             if (mFinishOpenTransaction != null) {
                 final SurfaceControl.Transaction t = mFinishOpenTransaction;
-                mFinishOpenTransaction = null;
                 t.apply();
             }
             if (mFinishOpenTransitionCallback != null) {
                 final Transitions.TransitionFinishCallback callback = mFinishOpenTransitionCallback;
-                mFinishOpenTransitionCallback = null;
                 callback.onTransitionFinished(null);
             }
+            cleanUpInternalState();
+        }
+
+        private void cleanUpInternalState() {
+            mOpenTransitionInfo = null;
+            mPrepareOpenTransition = null;
+            mFinishOpenTransaction = null;
+            mFinishOpenTransitionCallback = null;
+            mTakeoverHandler = null;
         }
 
         private void applyAndFinish(@NonNull SurfaceControl.Transaction st,
@@ -1237,6 +1266,7 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
             finishCallback.onTransitionFinished(null);
             mCloseTransitionRequested = false;
         }
+
         @Override
         public boolean startAnimation(@NonNull IBinder transition,
                 @NonNull TransitionInfo info,
@@ -1246,6 +1276,9 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
             final boolean isPrepareTransition =
                     info.getType() == WindowManager.TRANSIT_PREPARE_BACK_NAVIGATION;
             if (isPrepareTransition) {
+                if (checkTakeoverFlags()) {
+                    mTakeoverHandler = mTransitions.getHandlerForTakeover(transition, info);
+                }
                 kickStartAnimation();
             }
             // Both mShellExecutor and Transitions#mMainExecutor are ShellMainThread, so we don't
@@ -1288,6 +1321,57 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
             return handleCloseTransition(info, st, ft, finishCallback);
         }
 
+        private boolean canHandOffAnimation() {
+            if (!checkTakeoverFlags()) {
+                return false;
+            }
+
+            return mTakeoverHandler != null;
+        }
+
+        private void handOffAnimation(
+                RemoteAnimationTarget[] targets, WindowAnimationState[] states) {
+            if (!checkTakeoverFlags()) {
+                ProtoLog.e(WM_SHELL_BACK_PREVIEW,
+                        "Trying to hand off the animation, but the required flags are disabled.");
+                return;
+            } else if (mTakeoverHandler == null) {
+                ProtoLog.e(WM_SHELL_BACK_PREVIEW,
+                        "Missing takeover handler when trying to hand off animation.");
+                return;
+            } else if (targets.length != states.length) {
+                ProtoLog.e(WM_SHELL_BACK_PREVIEW,
+                        "Targets passed for takeover don't match the window states.");
+                return;
+            }
+
+            // The states passed to this method are paired with the targets, but they need to be
+            // paired with the changes inside the TransitionInfo. So for each change we find its
+            // matching target, and leave the state for any change missing a matching target blank.
+            WindowAnimationState[] updatedStates =
+                    new WindowAnimationState[mOpenTransitionInfo.getChanges().size()];
+            for (int i = 0; i < mOpenTransitionInfo.getChanges().size(); i++) {
+                ActivityManager.RunningTaskInfo taskInfo =
+                        mOpenTransitionInfo.getChanges().get(i).getTaskInfo();
+                if (taskInfo == null) {
+                    continue;
+                }
+
+                for (int j = 0; j < targets.length; j++) {
+                    if (taskInfo.taskId == targets[j].taskId) {
+                        updatedStates[i] = states[j];
+                        break;
+                    }
+                }
+            }
+
+            mTakeoverHandler.takeOverAnimation(
+                    mPrepareOpenTransition, mOpenTransitionInfo, new SurfaceControl.Transaction(),
+                    mFinishOpenTransitionCallback, updatedStates);
+
+            cleanUpInternalState();
+        }
+
         @Override
         public void onTransitionConsumed(@NonNull IBinder transition, boolean aborted,
                 @Nullable SurfaceControl.Transaction finishTransaction) {
@@ -1673,6 +1757,11 @@ public class BackAnimationController implements RemoteCallable<BackAnimationCont
             }
             return null;
         }
+
+        private static boolean checkTakeoverFlags() {
+            return TransitionAnimator.Companion.longLivedReturnAnimationsEnabled()
+                    && Flags.unifyBackNavigationTransition();
+        }
     }
 
     private static boolean isNotGestureBackTransition(@NonNull TransitionInfo info) {
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/BackAnimationControllerTest.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/BackAnimationControllerTest.java
index 13a8518ae8ed..c3e396524da1 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/BackAnimationControllerTest.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/back/BackAnimationControllerTest.java
@@ -57,6 +57,8 @@ import android.os.Handler;
 import android.os.IBinder;
 import android.os.RemoteCallback;
 import android.os.RemoteException;
+import android.platform.test.annotations.EnableFlags;
+import android.platform.test.flag.junit.SetFlagsRule;
 import android.provider.Settings;
 import android.testing.AndroidTestingRunner;
 import android.testing.TestableContentResolver;
@@ -91,6 +93,7 @@ import com.android.wm.shell.sysui.ShellInit;
 import com.android.wm.shell.transition.Transitions;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
@@ -140,6 +143,8 @@ public class BackAnimationControllerTest extends ShellTestCase {
     private RootTaskDisplayAreaOrganizer mRootTaskDisplayAreaOrganizer;
     @Mock
     private Handler mHandler;
+    @Mock
+    private Transitions.TransitionHandler mTakeoverHandler;
 
     private BackAnimationController mController;
     private TestableContentResolver mContentResolver;
@@ -152,6 +157,9 @@ public class BackAnimationControllerTest extends ShellTestCase {
 
     private BackAnimationController.BackTransitionHandler mBackTransitionHandler;
 
+    @Rule
+    public SetFlagsRule mSetflagsRule = new SetFlagsRule();
+
     @Before
     public void setUp() throws Exception {
         MockitoAnnotations.initMocks(this);
@@ -605,6 +613,51 @@ public class BackAnimationControllerTest extends ShellTestCase {
         verify(mAnimatorCallback, never()).onBackInvoked();
     }
 
+    @EnableFlags({com.android.systemui.shared.Flags.FLAG_RETURN_ANIMATION_FRAMEWORK_LIBRARY,
+            com.android.systemui.shared.Flags.FLAG_RETURN_ANIMATION_FRAMEWORK_LONG_LIVED,
+            com.android.window.flags.Flags.FLAG_UNIFY_BACK_NAVIGATION_TRANSITION})
+    @Test
+    public void appCallback_receivesTakeoverHandler_whenAvailable() throws RemoteException {
+        registerAnimation(BackNavigationInfo.TYPE_CROSS_TASK);
+        mBackTransitionHandler.mTakeoverHandler = mTakeoverHandler;
+
+        final int type = BackNavigationInfo.TYPE_CALLBACK;
+        final ResultListener result = new ResultListener();
+        createNavigationInfo(new BackNavigationInfo.Builder()
+                .setType(type)
+                .setOnBackInvokedCallback(mAppCallback)
+                .setOnBackNavigationDone(new RemoteCallback(result))
+                .setTouchableRegion(mTouchableRegion)
+                .setAppProgressAllowed(true));
+
+        triggerBackGesture();
+        mShellExecutor.flushAll();
+        releaseBackGesture();
+        mShellExecutor.flushAll();
+
+        verify(mAppCallback).setHandoffHandler(any());
+    }
+
+    @Test
+    public void appCallback_doesNotReceiveTakeoverHandler_whenUnavailable() throws RemoteException {
+        registerAnimation(BackNavigationInfo.TYPE_CROSS_TASK);
+
+        final int type = BackNavigationInfo.TYPE_CALLBACK;
+        final ResultListener result = new ResultListener();
+        createNavigationInfo(new BackNavigationInfo.Builder()
+                .setType(type)
+                .setOnBackInvokedCallback(mAppCallback)
+                .setOnBackNavigationDone(new RemoteCallback(result))
+                .setTouchableRegion(mTouchableRegion)
+                .setAppProgressAllowed(true));
+        triggerBackGesture();
+        mShellExecutor.flushAll();
+        releaseBackGesture();
+        mShellExecutor.flushAll();
+
+        verify(mAppCallback, never()).setHandoffHandler(any());
+    }
+
     @Test
     public void skipsCancelWithoutStart() throws RemoteException {
         final int type = BackNavigationInfo.TYPE_CALLBACK;
diff --git a/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java b/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java
index d6be9159694b..40da9ea2d718 100644
--- a/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/BackNavigationControllerTests.java
@@ -66,6 +66,7 @@ import android.view.WindowManager;
 import android.window.BackAnimationAdapter;
 import android.window.BackMotionEvent;
 import android.window.BackNavigationInfo;
+import android.window.IBackAnimationHandoffHandler;
 import android.window.IOnBackInvokedCallback;
 import android.window.OnBackInvokedCallback;
 import android.window.OnBackInvokedCallbackInfo;
@@ -780,6 +781,10 @@ public class BackNavigationControllerTests extends WindowTestsBase {
             @Override
             public void setTriggerBack(boolean triggerBack) {
             }
+
+            @Override
+            public void setHandoffHandler(IBackAnimationHandoffHandler unused) {
+            }
         };
     }
 
-- 
cgit v1.2.3-59-g8ed1b