Add IHomeTransitionListener to shell.

This allows launcher to listen in on any transitions that include the home
activity.

Bug: 279514548
Bug: 284474103
Test: Enable ENABLE_HOME_TRANSITION_LISTENER in launcher dev options
      App launch => Hotseat -> Taskbar -> Stash
      Launch translucent activity => No animation
      Go home from app => Taskbaer -> Hotseat

Change-Id: I574b8164bd61475ba05bbb86aef358f364227e66

4 files changed, 170 insertions, 2 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/HomeTransitionObserver.java b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/HomeTransitionObserver.java
new file mode 100644
index 000000000000..f561aa5568be
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/HomeTransitionObserver.java
@@ -0,0 +1,119 @@
+/*
+ * 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.transition;
+
+import static android.app.WindowConfiguration.ACTIVITY_TYPE_HOME;
+
+import static com.android.wm.shell.transition.Transitions.TransitionObserver;
+
+import android.annotation.NonNull;
+import android.app.ActivityManager;
+import android.content.Context;
+import android.os.IBinder;
+import android.view.SurfaceControl;
+import android.window.TransitionInfo;
+
+import com.android.wm.shell.common.RemoteCallable;
+import com.android.wm.shell.common.ShellExecutor;
+import com.android.wm.shell.common.SingleInstanceRemoteListener;
+import com.android.wm.shell.util.TransitionUtil;
+
+/**
+ * The {@link TransitionObserver} that observes for transitions involving the home
+ * activity. It reports transitions to the caller via {@link IHomeTransitionListener}.
+ */
+public class HomeTransitionObserver implements TransitionObserver,
+        RemoteCallable<HomeTransitionObserver> {
+    private final SingleInstanceRemoteListener<HomeTransitionObserver, IHomeTransitionListener>
+            mListener;
+
+    private @NonNull final Context mContext;
+    private @NonNull final ShellExecutor mMainExecutor;
+    private @NonNull final Transitions mTransitions;
+
+    public HomeTransitionObserver(@NonNull Context context,
+            @NonNull ShellExecutor mainExecutor,
+            @NonNull Transitions transitions) {
+        mContext = context;
+        mMainExecutor = mainExecutor;
+        mTransitions = transitions;
+
+        mListener = new SingleInstanceRemoteListener<>(this,
+                c -> mTransitions.registerObserver(this),
+                c -> mTransitions.unregisterObserver(this));
+
+    }
+
+    @Override
+    public void onTransitionReady(@NonNull IBinder transition,
+            @NonNull TransitionInfo info,
+            @NonNull SurfaceControl.Transaction startTransaction,
+            @NonNull SurfaceControl.Transaction finishTransaction) {
+        for (TransitionInfo.Change change : info.getChanges()) {
+            final ActivityManager.RunningTaskInfo taskInfo = change.getTaskInfo();
+            if (taskInfo == null || taskInfo.taskId == -1) {
+                continue;
+            }
+
+            final int mode = change.getMode();
+            if (taskInfo.getActivityType() == ACTIVITY_TYPE_HOME
+                    && TransitionUtil.isOpenOrCloseMode(mode)) {
+                mListener.call(l -> l.onHomeVisibilityChanged(TransitionUtil.isOpeningType(mode)));
+            }
+        }
+    }
+
+    @Override
+    public void onTransitionStarting(@NonNull IBinder transition) {}
+
+    @Override
+    public void onTransitionMerged(@NonNull IBinder merged,
+            @NonNull IBinder playing) {}
+
+    @Override
+    public void onTransitionFinished(@NonNull IBinder transition,
+            boolean aborted) {}
+
+    /**
+     * Sets the home transition listener that receives any transitions resulting in a change of
+     *
+     */
+    public void setHomeTransitionListener(IHomeTransitionListener listener) {
+        if (listener != null) {
+            mListener.register(listener);
+        } else {
+            mListener.unregister();
+        }
+    }
+
+    @Override
+    public Context getContext() {
+        return mContext;
+    }
+
+    @Override
+    public ShellExecutor getRemoteCallExecutor() {
+        return mMainExecutor;
+    }
+
+    /**
+     * Invalidates this controller, preventing future calls to send updates.
+     */
+    public void invalidate() {
+        mTransitions.unregisterObserver(this);
+    }
+}
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IHomeTransitionListener.aidl b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IHomeTransitionListener.aidl
new file mode 100644
index 000000000000..18716c68da27
--- /dev/null
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IHomeTransitionListener.aidl
@@ -0,0 +1,32 @@
+/*
+ * 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.transition;
+
+import android.window.RemoteTransition;
+import android.window.TransitionFilter;
+
+/**
+ *  Listener interface that Launcher attaches to SystemUI to get home activity transition callbacks.
+ */
+interface IHomeTransitionListener {
+
+    /**
+     * Called when a transition changes the visibility of the home activity.
+     */
+    void onHomeVisibilityChanged(in boolean isVisible);
+}
+
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IShellTransitions.aidl b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IShellTransitions.aidl
index cc4d268a0000..644a6a5114a7 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IShellTransitions.aidl
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/IShellTransitions.aidl
@@ -19,6 +19,8 @@ package com.android.wm.shell.transition;
 import android.window.RemoteTransition;
 import android.window.TransitionFilter;
 
+import com.android.wm.shell.transition.IHomeTransitionListener;
+
 /**
  * Interface that is exposed to remote callers to manipulate the transitions feature.
  */
@@ -39,4 +41,7 @@ interface IShellTransitions {
      * Retrieves the apply-token used by transactions in Shell
      */
     IBinder getShellApplyToken() = 3;
+
+    /** Set listener that will receive callbacks about transitions involving home activity */
+    oneway void setHomeTransitionListener(in IHomeTransitionListener listener) = 4;
 }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java
index 576bba96044c..baa9acaafa4b 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java
@@ -356,7 +356,7 @@ public class Transitions implements RemoteCallable<Transitions>,
     }
 
     private ExternalInterfaceBinder createExternalInterface() {
-        return new IShellTransitionsImpl(this);
+        return new IShellTransitionsImpl(mContext, getMainExecutor(), this);
     }
 
     @Override
@@ -1400,9 +1400,12 @@ public class Transitions implements RemoteCallable<Transitions>,
     private static class IShellTransitionsImpl extends IShellTransitions.Stub
             implements ExternalInterfaceBinder {
         private Transitions mTransitions;
+        private final HomeTransitionObserver mHomeTransitionObserver;
 
-        IShellTransitionsImpl(Transitions transitions) {
+        IShellTransitionsImpl(Context context, ShellExecutor executor, Transitions transitions) {
             mTransitions = transitions;
+            mHomeTransitionObserver = new HomeTransitionObserver(context, executor,
+                    mTransitions);
         }
 
         /**
@@ -1410,6 +1413,7 @@ public class Transitions implements RemoteCallable<Transitions>,
          */
         @Override
         public void invalidate() {
+            mHomeTransitionObserver.invalidate();
             mTransitions = null;
         }
 
@@ -1434,6 +1438,14 @@ public class Transitions implements RemoteCallable<Transitions>,
         public IBinder getShellApplyToken() {
             return SurfaceControl.Transaction.getDefaultApplyToken();
         }
+
+        @Override
+        public void setHomeTransitionListener(IHomeTransitionListener listener) {
+            executeRemoteCallWithTaskPermission(mTransitions, "setHomeTransitionListener",
+                    (transitions) -> {
+                        mHomeTransitionObserver.setHomeTransitionListener(listener);
+                    });
+        }
     }
 
     private class SettingsObserver extends ContentObserver {