From 990c149544e2fa5d7c38e83e3eb4fed23854adae Mon Sep 17 00:00:00 2001
From: Ben Lin <linben@google.com>
Date: Tue, 27 Sep 2022 15:29:39 -0700
Subject: [PATCH] Bring other Desktop apps to front when opening a new one.

This enables the launcher to bring all desktop apps to the front when
launching a new app. This is only enabled when Desktop Mode feature flag
is enabled and Shell transition is enabled.

Bug: None
Test: Manual, launch new apps from launcher
Change-Id: I5ae3941c7d27db3180ea6725a37868416b6649fb
---
 .../desktopmode/DesktopModeController.java    | 48 +++++++++++++++++--
 .../wm/shell/transition/Transitions.java      | 16 +++++++
 2 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopModeController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopModeController.java
index 99739c457aa67..dc7ed15dbe3a1 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopModeController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopModeController.java
@@ -19,6 +19,7 @@ package com.android.wm.shell.desktopmode;
 import static android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM;
 import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.view.WindowManager.TRANSIT_CHANGE;
+import static android.view.WindowManager.TRANSIT_OPEN;
 
 import static com.android.wm.shell.common.ExecutorUtils.executeRemoteCallWithTaskPermission;
 import static com.android.wm.shell.protolog.ShellProtoLogGroup.WM_SHELL_DESKTOP_MODE;
@@ -29,13 +30,18 @@ import android.content.Context;
 import android.database.ContentObserver;
 import android.net.Uri;
 import android.os.Handler;
+import android.os.IBinder;
 import android.os.UserHandle;
 import android.provider.Settings;
 import android.util.ArraySet;
+import android.view.SurfaceControl;
 import android.window.DisplayAreaInfo;
+import android.window.TransitionInfo;
+import android.window.TransitionRequestInfo;
 import android.window.WindowContainerTransaction;
 
 import androidx.annotation.BinderThread;
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
 import com.android.internal.annotations.VisibleForTesting;
@@ -55,7 +61,8 @@ import java.util.Comparator;
 /**
  * Handles windowing changes when desktop mode system setting changes
  */
-public class DesktopModeController implements RemoteCallable<DesktopModeController> {
+public class DesktopModeController implements RemoteCallable<DesktopModeController>,
+        Transitions.TransitionHandler {
 
     private final Context mContext;
     private final ShellTaskOrganizer mShellTaskOrganizer;
@@ -89,6 +96,7 @@ public class DesktopModeController implements RemoteCallable<DesktopModeControll
         if (DesktopModeStatus.isActive(mContext)) {
             updateDesktopModeActive(true);
         }
+        mTransitions.addHandler(this);
     }
 
     @Override
@@ -157,7 +165,7 @@ public class DesktopModeController implements RemoteCallable<DesktopModeControll
     /**
      * Show apps on desktop
      */
-    public void showDesktopApps() {
+    WindowContainerTransaction showDesktopApps() {
         ArraySet<Integer> activeTasks = mDesktopModeTaskRepository.getActiveTasks();
         ProtoLog.d(WM_SHELL_DESKTOP_MODE, "bringDesktopAppsToFront: tasks=%s", activeTasks.size());
         ArrayList<RunningTaskInfo> taskInfos = new ArrayList<>();
@@ -173,7 +181,12 @@ public class DesktopModeController implements RemoteCallable<DesktopModeControll
         for (RunningTaskInfo task : taskInfos) {
             wct.reorder(task.token, true);
         }
-        mShellTaskOrganizer.applyTransaction(wct);
+
+        if (!Transitions.ENABLE_SHELL_TRANSITIONS) {
+            mShellTaskOrganizer.applyTransaction(wct);
+        }
+
+        return wct;
     }
 
     /**
@@ -195,6 +208,35 @@ public class DesktopModeController implements RemoteCallable<DesktopModeControll
                 .configuration.windowConfiguration.getWindowingMode();
     }
 
+    @Override
+    public boolean startAnimation(@NonNull IBinder transition, @NonNull TransitionInfo info,
+            @NonNull SurfaceControl.Transaction startTransaction,
+            @NonNull SurfaceControl.Transaction finishTransaction,
+            @NonNull Transitions.TransitionFinishCallback finishCallback) {
+        // This handler should never be the sole handler, so should not animate anything.
+        return false;
+    }
+
+    @Nullable
+    @Override
+    public WindowContainerTransaction handleRequest(@NonNull IBinder transition,
+            @NonNull TransitionRequestInfo request) {
+
+        // Only do anything if we are in desktop mode and opening a task/app
+        if (!DesktopModeStatus.isActive(mContext) || request.getType() != TRANSIT_OPEN) {
+            return null;
+        }
+
+        WindowContainerTransaction wct = mTransitions.dispatchRequest(transition, request, this);
+        if (wct == null) {
+            wct = new WindowContainerTransaction();
+        }
+        wct.merge(showDesktopApps(), true /* transfer */);
+        wct.reorder(request.getTriggerTask().token, true /* onTop */);
+
+        return wct;
+    }
+
     /**
      * A {@link ContentObserver} for listening to changes to {@link Settings.System#DESKTOP_MODE}
      */
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 29d25bc39223a..1e93a16fe1320 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
@@ -542,6 +542,22 @@ public class Transitions implements RemoteCallable<Transitions> {
                 "This shouldn't happen, maybe the default handler is broken.");
     }
 
+    /**
+     * Gives every handler (in order) a chance to handle request until one consumes the transition.
+     * @return the WindowContainerTransaction given by the handler which consumed the transition.
+     */
+    public WindowContainerTransaction dispatchRequest(@NonNull IBinder transition,
+            @NonNull TransitionRequestInfo request, @Nullable TransitionHandler skip) {
+        for (int i = mHandlers.size() - 1; i >= 0; --i) {
+            if (mHandlers.get(i) == skip) continue;
+            WindowContainerTransaction wct = mHandlers.get(i).handleRequest(transition, request);
+            if (wct != null) {
+                return wct;
+            }
+        }
+        return null;
+    }
+
     /** Special version of finish just for dealing with no-op/invalid transitions. */
     private void onAbort(IBinder transition) {
         onFinish(transition, null /* wct */, null /* wctCB */, true /* abort */);