Prep work for exposing split-screen APIs to Launcher

Bug: 179176511
Test: DragAndDropPolicyTest
Change-Id: Iff8e5df9df87779cf8a33430245fc5584928b33c

8 files changed, 340 insertions, 113 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/ShellCommandHandlerImpl.java b/libs/WindowManager/Shell/src/com/android/wm/shell/ShellCommandHandlerImpl.java
index 52648d915f2c..fe97e24fac41 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/ShellCommandHandlerImpl.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/ShellCommandHandlerImpl.java
@@ -16,7 +16,7 @@
 
 package com.android.wm.shell;
 
-import static com.android.wm.shell.splitscreen.SplitScreen.SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_BOTTOM_OR_RIGHT;
 
 import com.android.wm.shell.apppairs.AppPairs;
 import com.android.wm.shell.common.ShellExecutor;
@@ -155,7 +155,7 @@ public final class ShellCommandHandlerImpl {
         }
         final int taskId = new Integer(args[2]);
         final int sideStagePosition = args.length > 3
-                ? new Integer(args[3]) : SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
+                ? new Integer(args[3]) : STAGE_POSITION_BOTTOM_OR_RIGHT;
         mSplitScreenOptional.ifPresent(split -> split.moveToSideStage(taskId, sideStagePosition));
         return true;
     }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropPolicy.java b/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropPolicy.java
index 800150c0a93c..35dcdd5923a8 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropPolicy.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/draganddrop/DragAndDropPolicy.java
@@ -34,8 +34,11 @@ import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPL
 import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPLIT_LEFT;
 import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPLIT_RIGHT;
 import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPLIT_TOP;
-import static com.android.wm.shell.splitscreen.SplitScreen.SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
-import static com.android.wm.shell.splitscreen.SplitScreen.SIDE_STAGE_POSITION_TOP_OR_LEFT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_BOTTOM_OR_RIGHT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_TOP_OR_LEFT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_UNDEFINED;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_SIDE;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_UNDEFINED;
 
 import android.app.ActivityManager;
 import android.app.ActivityTaskManager;
@@ -84,8 +87,7 @@ public class DragAndDropPolicy {
     private DragSession mSession;
 
     public DragAndDropPolicy(Context context, SplitScreen splitScreen) {
-        this(context, ActivityTaskManager.getInstance(), splitScreen,
-                new DefaultStarter(context, splitScreen));
+        this(context, ActivityTaskManager.getInstance(), splitScreen, new DefaultStarter(context));
     }
 
     @VisibleForTesting
@@ -94,7 +96,7 @@ public class DragAndDropPolicy {
         mContext = context;
         mActivityTaskManager = activityTaskManager;
         mSplitScreen = splitScreen;
-        mStarter = starter;
+        mStarter = mSplitScreen != null ? mSplitScreen : starter;
     }
 
     /**
@@ -195,39 +197,23 @@ public class DragAndDropPolicy {
             return;
         }
 
-        final ClipDescription description = data.getDescription();
-        final boolean isTask = description.hasMimeType(MIMETYPE_APPLICATION_TASK);
-        final boolean isShortcut = description.hasMimeType(MIMETYPE_APPLICATION_SHORTCUT);
-        final Intent dragData = mSession.dragData;
         final boolean inSplitScreen = mSplitScreen != null && mSplitScreen.isSplitScreenVisible();
         final boolean leftOrTop = target.type == TYPE_SPLIT_TOP || target.type == TYPE_SPLIT_LEFT;
-        final Bundle opts = dragData.hasExtra(EXTRA_ACTIVITY_OPTIONS)
-                ? dragData.getBundleExtra(EXTRA_ACTIVITY_OPTIONS)
-                : new Bundle();
-
-        if (target.type == TYPE_FULLSCREEN) {
-            // Exit split stages if needed
-            mStarter.exitSplitScreen();
-        } else if (mSplitScreen != null) {
+
+        @SplitScreen.StageType int stage = STAGE_TYPE_UNDEFINED;
+        @SplitScreen.StagePosition int position = STAGE_POSITION_UNDEFINED;
+        if (target.type != TYPE_FULLSCREEN && mSplitScreen != null) {
             // Update launch options for the split side we are targeting.
-            final int position = leftOrTop
-                    ? SIDE_STAGE_POSITION_TOP_OR_LEFT : SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
+            position = leftOrTop ? STAGE_POSITION_TOP_OR_LEFT : STAGE_POSITION_BOTTOM_OR_RIGHT;
             if (!inSplitScreen) {
-                // Update the side stage position to match where we want to launch.
-                mSplitScreen.setSideStagePosition(position);
+                // Launch in the side stage if we are not in split-screen already.
+                stage = STAGE_TYPE_SIDE;
             }
-            mSplitScreen.updateActivityOptions(opts, position);
         }
 
-        if (isTask) {
-            mStarter.startTask(dragData.getIntExtra(EXTRA_TASK_ID, INVALID_TASK_ID), opts);
-        } else if (isShortcut) {
-            mStarter.startShortcut(dragData.getStringExtra(EXTRA_PACKAGE_NAME),
-                    dragData.getStringExtra(EXTRA_SHORTCUT_ID),
-                    opts, dragData.getParcelableExtra(EXTRA_USER));
-        } else {
-            mStarter.startIntent(dragData.getParcelableExtra(EXTRA_PENDING_INTENT), opts);
-        }
+        final ClipDescription description = data.getDescription();
+        final Intent dragData = mSession.dragData;
+        mStarter.startClipDescription(description, dragData, stage, position);
     }
 
     /**
@@ -247,7 +233,6 @@ public class DragAndDropPolicy {
         int runningTaskActType = ACTIVITY_TYPE_STANDARD;
         boolean runningTaskIsResizeable;
         boolean dragItemSupportsSplitscreen;
-        boolean isPhone;
 
         DragSession(Context context, ActivityTaskManager activityTaskManager,
                 DisplayLayout dispLayout, ClipData data) {
@@ -275,7 +260,6 @@ public class DragAndDropPolicy {
             final ActivityInfo info = mInitialDragData.getItemAt(0).getActivityInfo();
             dragItemSupportsSplitscreen = info == null
                     || ActivityInfo.isResizeableMode(info.resizeMode);
-            isPhone = mContext.getResources().getConfiguration().smallestScreenWidthDp < 600;
             dragData = mInitialDragData.getItemAt(0).getIntent();
         }
     }
@@ -284,11 +268,33 @@ public class DragAndDropPolicy {
      * Interface for actually committing the task launches.
      */
     @VisibleForTesting
-    interface Starter {
-        void startTask(int taskId, Bundle activityOptions);
-        void startShortcut(String packageName, String shortcutId, Bundle activityOptions,
-                UserHandle user);
-        void startIntent(PendingIntent intent, Bundle activityOptions);
+    public interface Starter {
+        default void startClipDescription(ClipDescription description, Intent intent,
+                @SplitScreen.StageType int stage, @SplitScreen.StagePosition int position) {
+            final boolean isTask = description.hasMimeType(MIMETYPE_APPLICATION_TASK);
+            final boolean isShortcut = description.hasMimeType(MIMETYPE_APPLICATION_SHORTCUT);
+            final Bundle opts = intent.hasExtra(EXTRA_ACTIVITY_OPTIONS)
+                    ? intent.getBundleExtra(EXTRA_ACTIVITY_OPTIONS) : new Bundle();
+
+            if (isTask) {
+                final int taskId = intent.getIntExtra(EXTRA_TASK_ID, INVALID_TASK_ID);
+                startTask(taskId, stage, position, opts);
+            } else if (isShortcut) {
+                final String packageName = intent.getStringExtra(EXTRA_PACKAGE_NAME);
+                final String id = intent.getStringExtra(EXTRA_SHORTCUT_ID);
+                final UserHandle user = intent.getParcelableExtra(EXTRA_USER);
+                startShortcut(packageName, id, stage, position, opts, user);
+            } else {
+                startIntent(intent.getParcelableExtra(EXTRA_PENDING_INTENT), stage, position, opts);
+            }
+        }
+        void startTask(int taskId, @SplitScreen.StageType int stage,
+                @SplitScreen.StagePosition int position, @Nullable Bundle options);
+        void startShortcut(String packageName, String shortcutId,
+                @SplitScreen.StageType int stage, @SplitScreen.StagePosition int position,
+                @Nullable Bundle options, UserHandle user);
+        void startIntent(PendingIntent intent, @SplitScreen.StageType int stage,
+                @SplitScreen.StagePosition int position, @Nullable Bundle options);
         void enterSplitScreen(int taskId, boolean leftOrTop);
         void exitSplitScreen();
     }
@@ -299,39 +305,39 @@ public class DragAndDropPolicy {
      */
     private static class DefaultStarter implements Starter {
         private final Context mContext;
-        private final SplitScreen mSplitScreen;
 
-        public DefaultStarter(Context context, SplitScreen splitScreen) {
+        public DefaultStarter(Context context) {
             mContext = context;
-            mSplitScreen = splitScreen;
         }
 
         @Override
-        public void startTask(int taskId, Bundle activityOptions) {
+        public void startTask(int taskId, int stage, int position,
+                @Nullable Bundle options) {
             try {
-                ActivityTaskManager.getService().startActivityFromRecents(taskId, activityOptions);
+                ActivityTaskManager.getService().startActivityFromRecents(taskId, options);
             } catch (RemoteException e) {
                 Slog.e(TAG, "Failed to launch task", e);
             }
         }
 
         @Override
-        public void startShortcut(String packageName, String shortcutId, Bundle activityOptions,
-                UserHandle user) {
+        public void startShortcut(String packageName, String shortcutId, int stage, int position,
+                @Nullable Bundle options, UserHandle user) {
             try {
                 LauncherApps launcherApps =
                         mContext.getSystemService(LauncherApps.class);
                 launcherApps.startShortcut(packageName, shortcutId, null /* sourceBounds */,
-                        activityOptions, user);
+                        options, user);
             } catch (ActivityNotFoundException e) {
                 Slog.e(TAG, "Failed to launch shortcut", e);
             }
         }
 
         @Override
-        public void startIntent(PendingIntent intent, Bundle activityOptions) {
+        public void startIntent(PendingIntent intent, int stage, int position,
+                @Nullable Bundle options) {
             try {
-                intent.send(null, 0, null, null, null, null, activityOptions);
+                intent.send(null, 0, null, null, null, null, options);
             } catch (PendingIntent.CanceledException e) {
                 Slog.e(TAG, "Failed to launch activity", e);
             }
@@ -339,14 +345,12 @@ public class DragAndDropPolicy {
 
         @Override
         public void enterSplitScreen(int taskId, boolean leftOrTop) {
-            mSplitScreen.moveToSideStage(taskId,
-                    leftOrTop ? SIDE_STAGE_POSITION_TOP_OR_LEFT
-                            : SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT);
+            throw new UnsupportedOperationException("enterSplitScreen not implemented by starter");
         }
 
         @Override
         public void exitSplitScreen() {
-            mSplitScreen.exitSplitScreen();
+            throw new UnsupportedOperationException("exitSplitScreen not implemented by starter");
         }
     }
 
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreen.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreen.java
index 7c1b9d813851..2c6809259459 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreen.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreen.java
@@ -18,12 +18,16 @@ package com.android.wm.shell.splitscreen;
 
 import android.annotation.IntDef;
 import android.app.ActivityManager;
+import android.app.PendingIntent;
 import android.graphics.Rect;
 import android.os.Bundle;
+import android.os.UserHandle;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import com.android.wm.shell.common.annotations.ExternalThread;
+import com.android.wm.shell.draganddrop.DragAndDropPolicy;
 
 import java.io.PrintWriter;
 
@@ -31,46 +35,93 @@ import java.io.PrintWriter;
  * Interface to engage split-screen feature.
  */
 @ExternalThread
-public interface SplitScreen {
+public interface SplitScreen extends DragAndDropPolicy.Starter {
     /**
-     * Specifies that the side-stage is positioned at the top half of the screen if
+     * Stage position isn't specified normally meaning to use what ever it is currently set to.
+     */
+    int STAGE_POSITION_UNDEFINED = -1;
+    /**
+     * Specifies that a stage is positioned at the top half of the screen if
      * in portrait mode or at the left half of the screen if in landscape mode.
      */
-    int SIDE_STAGE_POSITION_TOP_OR_LEFT = 0;
+    int STAGE_POSITION_TOP_OR_LEFT = 0;
 
     /**
-     * Specifies that the side-stage is positioned at the bottom half of the screen if
+     * Specifies that a stage is positioned at the bottom half of the screen if
      * in portrait mode or at the right half of the screen if in landscape mode.
      */
-    int SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT = 1;
+    int STAGE_POSITION_BOTTOM_OR_RIGHT = 1;
 
-    @IntDef(prefix = { "SIDE_STAGE_POSITION_" }, value = {
-            SIDE_STAGE_POSITION_TOP_OR_LEFT,
-            SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT
+    @IntDef(prefix = { "STAGE_POSITION_" }, value = {
+            STAGE_POSITION_UNDEFINED,
+            STAGE_POSITION_TOP_OR_LEFT,
+            STAGE_POSITION_BOTTOM_OR_RIGHT
     })
-    @interface SideStagePosition {}
+    @interface StagePosition {}
+
+    /**
+     * Stage type isn't specified normally meaning to use what ever the default is.
+     * E.g. exit split-screen and launch the app in fullscreen.
+     */
+    int STAGE_TYPE_UNDEFINED = -1;
+    /**
+     * The main stage type.
+     * @see MainStage
+     */
+    int STAGE_TYPE_MAIN = 0;
+
+    /**
+     * The side stage type.
+     * @see SideStage
+     */
+    int STAGE_TYPE_SIDE = 1;
+
+    @IntDef(prefix = { "STAGE_TYPE_" }, value = {
+            STAGE_TYPE_UNDEFINED,
+            STAGE_TYPE_MAIN,
+            STAGE_TYPE_SIDE
+    })
+    @interface StageType {}
+
+    /** Callback interface for listening to changes in a split-screen stage. */
+    interface SplitScreenListener {
+        void onStagePositionChanged(@StageType int stage, @StagePosition int position);
+        void onTaskStageChanged(int taskId, @StageType int stage);
+    }
 
     /** @return {@code true} if split-screen is currently visible. */
     boolean isSplitScreenVisible();
     /** Moves a task in the side-stage of split-screen. */
-    boolean moveToSideStage(int taskId, @SideStagePosition int sideStagePosition);
+    boolean moveToSideStage(int taskId, @StagePosition int sideStagePosition);
     /** Moves a task in the side-stage of split-screen. */
     boolean moveToSideStage(ActivityManager.RunningTaskInfo task,
-            @SideStagePosition int sideStagePosition);
+            @StagePosition int sideStagePosition);
     /** Removes a task from the side-stage of split-screen. */
     boolean removeFromSideStage(int taskId);
     /** Sets the position of the side-stage. */
-    void setSideStagePosition(@SideStagePosition int sideStagePosition);
+    void setSideStagePosition(@StagePosition int sideStagePosition);
     /** Hides the side-stage if it is currently visible. */
     void setSideStageVisibility(boolean visible);
+    default void enterSplitScreen(int taskId, boolean leftOrTop) {
+        moveToSideStage(taskId,
+                leftOrTop ? STAGE_POSITION_TOP_OR_LEFT : STAGE_POSITION_BOTTOM_OR_RIGHT);
+    }
     /** Removes the split-screen stages. */
     void exitSplitScreen();
     /** Gets the stage bounds. */
     void getStageBounds(Rect outTopOrLeftBounds, Rect outBottomOrRightBounds);
-    /** Updates the launch activity options for the split position we want to launch it in. */
-    void updateActivityOptions(Bundle opts, @SideStagePosition int position);
     /** Dumps current status of split-screen. */
     void dump(@NonNull PrintWriter pw, String prefix);
     /** Called when the shell organizer has been registered. */
     void onOrganizerRegistered();
+
+    void registerSplitScreenListener(SplitScreenListener listener);
+    void unregisterSplitScreenListener(SplitScreenListener listener);
+
+    void startTask(int taskId,
+            @StageType int stage, @StagePosition int position, @Nullable Bundle options);
+    void startShortcut(String packageName, String shortcutId, @StageType int stage,
+            @StagePosition int position, @Nullable Bundle options, UserHandle user);
+    void startIntent(PendingIntent intent,
+            @StageType int stage, @StagePosition int position, @Nullable Bundle options);
 }
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java
index 27d3b81d41b5..18dd53b90ff4 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenController.java
@@ -19,11 +19,19 @@ package com.android.wm.shell.splitscreen;
 import static android.view.Display.DEFAULT_DISPLAY;
 
 import android.app.ActivityManager;
+import android.app.ActivityTaskManager;
+import android.app.PendingIntent;
+import android.content.ActivityNotFoundException;
 import android.content.Context;
+import android.content.pm.LauncherApps;
 import android.graphics.Rect;
 import android.os.Bundle;
+import android.os.RemoteException;
+import android.os.UserHandle;
+import android.util.Slog;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 
 import com.android.wm.shell.RootTaskDisplayAreaOrganizer;
 import com.android.wm.shell.ShellTaskOrganizer;
@@ -69,7 +77,7 @@ public class SplitScreenController implements SplitScreen {
     }
 
     @Override
-    public boolean moveToSideStage(int taskId, @SideStagePosition int sideStagePosition) {
+    public boolean moveToSideStage(int taskId, @StagePosition int sideStagePosition) {
         final ActivityManager.RunningTaskInfo task = mTaskOrganizer.getRunningTaskInfo(taskId);
         if (task == null) {
             throw new IllegalArgumentException("Unknown taskId" + taskId);
@@ -79,7 +87,7 @@ public class SplitScreenController implements SplitScreen {
 
     @Override
     public boolean moveToSideStage(ActivityManager.RunningTaskInfo task,
-            @SideStagePosition int sideStagePosition) {
+            @StagePosition int sideStagePosition) {
         return mStageCoordinator.moveToSideStage(task, sideStagePosition);
     }
 
@@ -89,7 +97,7 @@ public class SplitScreenController implements SplitScreen {
     }
 
     @Override
-    public void setSideStagePosition(@SideStagePosition int sideStagePosition) {
+    public void setSideStagePosition(@StagePosition int sideStagePosition) {
         mStageCoordinator.setSideStagePosition(sideStagePosition);
     }
 
@@ -109,8 +117,103 @@ public class SplitScreenController implements SplitScreen {
     }
 
     @Override
-    public void updateActivityOptions(Bundle opts, @SideStagePosition int position) {
-        mStageCoordinator.updateActivityOptions(opts, position);
+    public void registerSplitScreenListener(SplitScreenListener listener) {
+        mStageCoordinator.registerSplitScreenListener(listener);
+    }
+
+    @Override
+    public void unregisterSplitScreenListener(SplitScreenListener listener) {
+        mStageCoordinator.unregisterSplitScreenListener(listener);
+    }
+
+    @Override
+    public void startTask(int taskId,
+            @StageType int stage, @StagePosition int position, @Nullable Bundle options) {
+        options = resolveStartStage(stage, position, options);
+
+        try {
+            ActivityTaskManager.getService().startActivityFromRecents(taskId, options);
+        } catch (RemoteException e) {
+            Slog.e(TAG, "Failed to launch task", e);
+        }
+    }
+
+    @Override
+    public void startShortcut(String packageName, String shortcutId, @StageType int stage,
+            @StagePosition int position, @Nullable Bundle options, UserHandle user) {
+        options = resolveStartStage(stage, position, options);
+
+        try {
+            LauncherApps launcherApps =
+                    mContext.getSystemService(LauncherApps.class);
+            launcherApps.startShortcut(packageName, shortcutId, null /* sourceBounds */,
+                    options, user);
+        } catch (ActivityNotFoundException e) {
+            Slog.e(TAG, "Failed to launch shortcut", e);
+        }
+    }
+
+    @Override
+    public void startIntent(PendingIntent intent,
+            @StageType int stage, @StagePosition int position, @Nullable Bundle options) {
+        options = resolveStartStage(stage, position, options);
+
+        try {
+            intent.send(null, 0, null, null, null, null, options);
+        } catch (PendingIntent.CanceledException e) {
+            Slog.e(TAG, "Failed to launch activity", e);
+        }
+    }
+
+    private Bundle resolveStartStage(@StageType int stage, @StagePosition int position,
+            @Nullable Bundle options) {
+        switch (stage) {
+            case STAGE_TYPE_UNDEFINED: {
+                // Use the stage of the specified position is valid.
+                if (position != STAGE_POSITION_UNDEFINED) {
+                    if (position == mStageCoordinator.getSideStagePosition()) {
+                        options = resolveStartStage(STAGE_TYPE_SIDE, position, options);
+                    } else {
+                        options = resolveStartStage(STAGE_TYPE_MAIN, position, options);
+                    }
+                } else {
+                    // Exit split-screen and launch fullscreen since stage wasn't specified.
+                    mStageCoordinator.exitSplitScreen();
+                }
+                break;
+            }
+            case STAGE_TYPE_SIDE: {
+                if (position != STAGE_POSITION_UNDEFINED) {
+                    mStageCoordinator.setSideStagePosition(position);
+                } else {
+                    position = mStageCoordinator.getSideStagePosition();
+                }
+                if (options == null) {
+                    options = new Bundle();
+                }
+                mStageCoordinator.updateActivityOptions(options, position);
+                break;
+            }
+            case STAGE_TYPE_MAIN: {
+                if (position != STAGE_POSITION_UNDEFINED) {
+                    // Set the side stage opposite of what we want to the main stage.
+                    final int sideStagePosition = position == STAGE_POSITION_TOP_OR_LEFT
+                            ? STAGE_POSITION_BOTTOM_OR_RIGHT : STAGE_POSITION_TOP_OR_LEFT;
+                    mStageCoordinator.setSideStagePosition(sideStagePosition);
+                } else {
+                    position = mStageCoordinator.getMainStagePosition();
+                }
+                if (options == null) {
+                    options = new Bundle();
+                }
+                mStageCoordinator.updateActivityOptions(options, position);
+                break;
+            }
+            default:
+                throw new IllegalArgumentException("Unknown stage=" + stage);
+        }
+
+        return options;
     }
 
     @Override
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
index d571e7514542..176852b148fa 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
@@ -17,12 +17,14 @@
 package com.android.wm.shell.splitscreen;
 
 import static android.app.ActivityOptions.KEY_LAUNCH_ROOT_TASK_TOKEN;
-import static android.app.ActivityTaskManager.INVALID_TASK_ID;
 import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.app.WindowConfiguration.WINDOWING_MODE_MULTI_WINDOW;
 
-import static com.android.wm.shell.splitscreen.SplitScreen.SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
-import static com.android.wm.shell.splitscreen.SplitScreen.SIDE_STAGE_POSITION_TOP_OR_LEFT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_BOTTOM_OR_RIGHT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_TOP_OR_LEFT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_MAIN;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_SIDE;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_UNDEFINED;
 
 import android.app.ActivityManager;
 import android.content.Context;
@@ -41,6 +43,8 @@ import com.android.wm.shell.common.SyncTransactionQueue;
 import com.android.wm.shell.common.split.SplitLayout;
 
 import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Coordinates the staging (visibility, sizing, ...) of the split-screen {@link MainStage} and
@@ -64,8 +68,7 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
     private final StageListenerImpl mMainStageListener = new StageListenerImpl();
     private final SideStage mSideStage;
     private final StageListenerImpl mSideStageListener = new StageListenerImpl();
-    private @SplitScreen.SideStagePosition int mSideStagePosition =
-            SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
+    private @SplitScreen.StagePosition int mSideStagePosition = STAGE_POSITION_BOTTOM_OR_RIGHT;
 
     private final int mDisplayId;
     private SplitLayout mSplitLayout;
@@ -75,6 +78,7 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
     private final ShellTaskOrganizer mTaskOrganizer;
     private DisplayAreaInfo mDisplayAreaInfo;
     private final Context mContext;
+    private final List<SplitScreen.SplitScreenListener> mListeners = new ArrayList<>();
 
     StageCoordinator(Context context, int displayId, SyncTransactionQueue syncQueue,
             RootTaskDisplayAreaOrganizer rootTDAOrganizer, ShellTaskOrganizer taskOrganizer) {
@@ -107,7 +111,7 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
     }
 
     boolean moveToSideStage(ActivityManager.RunningTaskInfo task,
-            @SplitScreen.SideStagePosition int sideStagePosition) {
+            @SplitScreen.StagePosition int sideStagePosition) {
         final WindowContainerTransaction wct = new WindowContainerTransaction();
         mSideStagePosition = sideStagePosition;
         mMainStage.activate(getMainStageBounds(), wct);
@@ -130,7 +134,16 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
         return result;
     }
 
-    void setSideStagePosition(@SplitScreen.SideStagePosition int sideStagePosition) {
+    @SplitScreen.StagePosition int getSideStagePosition() {
+        return mSideStagePosition;
+    }
+
+    @SplitScreen.StagePosition int getMainStagePosition() {
+        return mSideStagePosition ==  STAGE_POSITION_TOP_OR_LEFT
+                ? STAGE_POSITION_BOTTOM_OR_RIGHT : STAGE_POSITION_TOP_OR_LEFT;
+    }
+
+    void setSideStagePosition(@SplitScreen.StagePosition int sideStagePosition) {
         mSideStagePosition = sideStagePosition;
         if (mSideStageListener.mVisible) {
             onStageVisibilityChanged(mSideStageListener);
@@ -163,7 +176,7 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
         outBottomOrRightBounds.set(mSplitLayout.getBounds2());
     }
 
-    void updateActivityOptions(Bundle opts, @SplitScreen.SideStagePosition int position) {
+    void updateActivityOptions(Bundle opts, @SplitScreen.StagePosition int position) {
         final StageTaskListener stage = position == mSideStagePosition ? mSideStage : mMainStage;
         opts.putParcelable(KEY_LAUNCH_ROOT_TASK_TOKEN, stage.mRootTaskInfo.token);
 
@@ -176,6 +189,35 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
         }
     }
 
+    void registerSplitScreenListener(SplitScreen.SplitScreenListener listener) {
+        if (mListeners.contains(listener)) return;
+        mListeners.add(listener);
+        listener.onStagePositionChanged(STAGE_TYPE_MAIN, getMainStagePosition());
+        listener.onStagePositionChanged(STAGE_TYPE_SIDE, getSideStagePosition());
+        mSideStage.onSplitScreenListenerRegistered(listener, STAGE_TYPE_SIDE);
+        mMainStage.onSplitScreenListenerRegistered(listener, STAGE_TYPE_MAIN);
+    }
+
+    void unregisterSplitScreenListener(SplitScreen.SplitScreenListener listener) {
+        mListeners.remove(listener);
+    }
+
+    private void onStageChildTaskStatusChanged(
+            StageListenerImpl stageListener, int taskId, boolean present) {
+
+        int stage;
+        if (present) {
+            stage = stageListener == mSideStageListener ? STAGE_TYPE_SIDE : STAGE_TYPE_MAIN;
+        } else {
+            // No longer on any stage
+            stage = STAGE_TYPE_UNDEFINED;
+        }
+
+        for (int i = mListeners.size() - 1; i >= 0; --i) {
+            mListeners.get(i).onTaskStageChanged(taskId, stage);
+        }
+    }
+
     private void onStageRootTaskAppeared(StageListenerImpl stageListener) {
         if (mMainStageListener.mHasRootTask && mSideStageListener.mHasRootTask) {
             final WindowContainerTransaction wct = new WindowContainerTransaction();
@@ -299,7 +341,7 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
     @Override
     public void onSnappedToDismiss(boolean bottomOrRight) {
         final boolean mainStageToTop = bottomOrRight
-                && mSideStagePosition == SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
+                && mSideStagePosition == STAGE_POSITION_BOTTOM_OR_RIGHT;
         exitSplitScreen(mainStageToTop ? mMainStage : mSideStage);
     }
 
@@ -326,8 +368,8 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
 
     @Override
     public void onDoubleTappedDivider() {
-        setSideStagePosition(mSideStagePosition == SIDE_STAGE_POSITION_TOP_OR_LEFT
-                ? SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT : SIDE_STAGE_POSITION_TOP_OR_LEFT);
+        setSideStagePosition(mSideStagePosition == STAGE_POSITION_TOP_OR_LEFT
+                ? STAGE_POSITION_BOTTOM_OR_RIGHT : STAGE_POSITION_TOP_OR_LEFT);
     }
 
     @Override
@@ -380,12 +422,12 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
     }
 
     private Rect getSideStageBounds() {
-        return mSideStagePosition == SIDE_STAGE_POSITION_TOP_OR_LEFT
+        return mSideStagePosition == STAGE_POSITION_TOP_OR_LEFT
                 ? mSplitLayout.getBounds1() : mSplitLayout.getBounds2();
     }
 
     private Rect getMainStageBounds() {
-        return mSideStagePosition == SIDE_STAGE_POSITION_TOP_OR_LEFT
+        return mSideStagePosition == STAGE_POSITION_TOP_OR_LEFT
                 ? mSplitLayout.getBounds2() : mSplitLayout.getBounds1();
     }
 
@@ -429,6 +471,11 @@ class StageCoordinator implements SplitLayout.LayoutChangeListener,
         }
 
         @Override
+        public void onChildTaskStatusChanged(int taskId, boolean present) {
+            StageCoordinator.this.onStageChildTaskStatusChanged(this, taskId, present);
+        }
+
+        @Override
         public void onRootTaskVanished() {
             reset();
             StageCoordinator.this.onStageRootTaskVanished(this);
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
index 1aa7552c01eb..653299326cd0 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageTaskListener.java
@@ -58,6 +58,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
     public interface StageListenerCallbacks {
         void onRootTaskAppeared();
         void onStatusChanged(boolean visible, boolean hasChildren);
+        void onChildTaskStatusChanged(int taskId, boolean present);
         void onRootTaskVanished();
     }
     private final StageListenerCallbacks mCallbacks;
@@ -83,9 +84,11 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
             mRootTaskInfo = taskInfo;
             mCallbacks.onRootTaskAppeared();
         } else if (taskInfo.parentTaskId == mRootTaskInfo.taskId) {
-            mChildrenLeashes.put(taskInfo.taskId, leash);
-            mChildrenTaskInfo.put(taskInfo.taskId, taskInfo);
+            final int taskId = taskInfo.taskId;
+            mChildrenLeashes.put(taskId, leash);
+            mChildrenTaskInfo.put(taskId, taskInfo);
             updateChildTaskSurface(taskInfo, leash, true /* firstAppeared */);
+            mCallbacks.onChildTaskStatusChanged(taskId, true /* present */);
         } else {
             throw new IllegalArgumentException(this + "\n Unknown task: " + taskInfo
                     + "\n mRootTaskInfo: " + mRootTaskInfo);
@@ -120,6 +123,7 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
             mChildrenTaskInfo.remove(taskId);
             mChildrenLeashes.remove(taskId);
             sendStatusChanged();
+            mCallbacks.onChildTaskStatusChanged(taskId, false /* present */);
         } else {
             throw new IllegalArgumentException(this + "\n Unknown task: " + taskInfo
                     + "\n mRootTaskInfo: " + mRootTaskInfo);
@@ -134,6 +138,13 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
         wct.reorder(mRootTaskInfo.token, visible /* onTop */);
     }
 
+    void onSplitScreenListenerRegistered(SplitScreen.SplitScreenListener listener,
+            @SplitScreen.StageType int stage) {
+        for (int i = mChildrenTaskInfo.size() - 1; i >= 0; --i) {
+            listener.onTaskStageChanged(mChildrenTaskInfo.keyAt(i), stage);
+        }
+    }
+
     private void updateChildTaskSurface(ActivityManager.RunningTaskInfo taskInfo,
             SurfaceControl leash, boolean firstAppeared) {
         final Point taskPositionInParent = taskInfo.positionInParent;
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropPolicyTest.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropPolicyTest.java
index 79bdaf43f171..25721066b713 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropPolicyTest.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/draganddrop/DragAndDropPolicyTest.java
@@ -29,6 +29,10 @@ import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPL
 import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPLIT_LEFT;
 import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPLIT_RIGHT;
 import static com.android.wm.shell.draganddrop.DragAndDropPolicy.Target.TYPE_SPLIT_TOP;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_BOTTOM_OR_RIGHT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_UNDEFINED;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_SIDE;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_UNDEFINED;
 
 import static junit.framework.Assert.assertTrue;
 import static junit.framework.Assert.fail;
@@ -86,11 +90,9 @@ public class DragAndDropPolicyTest {
     @Mock
     private ActivityTaskManager mActivityTaskManager;
 
+    // Both the split-screen and start interface.
     @Mock
-    private SplitScreen mSplitScreen;
-
-    @Mock
-    private DragAndDropPolicy.Starter mStarter;
+    private SplitScreen mSplitScreenStarter;
 
     private DisplayLayout mLandscapeDisplayLayout;
     private DisplayLayout mPortraitDisplayLayout;
@@ -126,7 +128,7 @@ public class DragAndDropPolicyTest {
         mInsets = Insets.of(0, 0, 0, 0);
 
         mPolicy = new DragAndDropPolicy(
-                mContext, mActivityTaskManager, mSplitScreen, mStarter);
+                mContext, mActivityTaskManager, mSplitScreenStarter, mSplitScreenStarter);
         mActivityClipData = createClipData(MIMETYPE_APPLICATION_ACTIVITY);
         mNonResizeableActivityClipData = createClipData(MIMETYPE_APPLICATION_ACTIVITY);
         setClipDataResizeable(mNonResizeableActivityClipData, false);
@@ -191,7 +193,7 @@ public class DragAndDropPolicyTest {
     }
 
     private void setInSplitScreen(boolean inSplitscreen) {
-        doReturn(inSplitscreen).when(mSplitScreen).isSplitScreenVisible();
+        doReturn(inSplitscreen).when(mSplitScreenStarter).isSplitScreenVisible();
     }
 
     @Test
@@ -202,7 +204,8 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
     }
 
     @Test
@@ -213,12 +216,13 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN, TYPE_SPLIT_LEFT, TYPE_SPLIT_RIGHT);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).exitSplitScreen();
-        verify(mStarter).startIntent(any(), any());
-        reset(mStarter);
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
+        reset(mSplitScreenStarter);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_SPLIT_RIGHT), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_SIDE), eq(STAGE_POSITION_BOTTOM_OR_RIGHT));
     }
 
     @Test
@@ -229,12 +233,13 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN, TYPE_SPLIT_TOP, TYPE_SPLIT_BOTTOM);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).exitSplitScreen();
-        verify(mStarter).startIntent(any(), any());
-        reset(mStarter);
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
+        reset(mSplitScreenStarter);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_SPLIT_BOTTOM), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_SIDE), eq(STAGE_POSITION_BOTTOM_OR_RIGHT));
     }
 
     @Test
@@ -245,7 +250,8 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN, TYPE_SPLIT_LEFT, TYPE_SPLIT_RIGHT);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
     }
 
     @Test
@@ -256,7 +262,8 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN, TYPE_SPLIT_LEFT, TYPE_SPLIT_RIGHT);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
     }
 
     @Test
@@ -268,12 +275,14 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN, TYPE_SPLIT_LEFT, TYPE_SPLIT_RIGHT);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
-        reset(mStarter);
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
+        reset(mSplitScreenStarter);
 
         // TODO(b/169894807): Just verify starting for the non-docked task until we have app pairs
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_SPLIT_RIGHT), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_SIDE), eq(STAGE_POSITION_BOTTOM_OR_RIGHT));
     }
 
     @Test
@@ -285,12 +294,14 @@ public class DragAndDropPolicyTest {
                 mPolicy.getTargets(mInsets), TYPE_FULLSCREEN, TYPE_SPLIT_TOP, TYPE_SPLIT_BOTTOM);
 
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_FULLSCREEN), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
-        reset(mStarter);
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_UNDEFINED), eq(STAGE_POSITION_UNDEFINED));
+        reset(mSplitScreenStarter);
 
         // TODO(b/169894807): Just verify starting for the non-docked task until we have app pairs
         mPolicy.handleDrop(filterTargetByType(targets, TYPE_SPLIT_BOTTOM), mActivityClipData);
-        verify(mStarter).startIntent(any(), any());
+        verify(mSplitScreenStarter).startClipDescription(any(), any(),
+                eq(STAGE_TYPE_SIDE), eq(STAGE_POSITION_BOTTOM_OR_RIGHT));
     }
 
     @Test
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java
index 168e0df35fe1..d2d18129d071 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/splitscreen/StageCoordinatorTests.java
@@ -19,7 +19,7 @@ package com.android.wm.shell.splitscreen;
 import static android.view.Display.DEFAULT_DISPLAY;
 import static android.window.DisplayAreaOrganizer.FEATURE_DEFAULT_TASK_CONTAINER;
 
-import static com.android.wm.shell.splitscreen.SplitScreen.SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT;
+import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_POSITION_BOTTOM_OR_RIGHT;
 
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
@@ -71,7 +71,7 @@ public class StageCoordinatorTests extends ShellTestCase {
     public void testMoveToSideStage() {
         final ActivityManager.RunningTaskInfo task = new TestRunningTaskInfoBuilder().build();
 
-        mStageCoordinator.moveToSideStage(task, SIDE_STAGE_POSITION_BOTTOM_OR_RIGHT);
+        mStageCoordinator.moveToSideStage(task, STAGE_POSITION_BOTTOM_OR_RIGHT);
 
         verify(mMainStage).activate(any(Rect.class), any(WindowContainerTransaction.class));
         verify(mSideStage).addTask(eq(task), any(Rect.class),