Fix the transition from Split to PiP

- Do not bring split to top on entering PiP
  When swiping up to home (or other cases) triggers one of the
  split-screen children enters PiP, do not try to bring the other task
  to top since the pair should be considered invisible.
- When entering PiP from split screen or non-auto PiP case, use the
  alpha information in PictureInPictureSurfaceTransaction to hide the
  task which would later be turned back on to avoid flicker.

Bug: 190855091
Bug: 205894095
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/42RWtayanp2qG0mHSf4Q5
Test: manual, enter PiP from split-screen, see Video
Change-Id: I1559748cd583c20d79ee458822d66e7801733d3a

3 files changed, 29 insertions, 2 deletions

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 05552aad2303..cf4e56e128bf 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
@@ -102,6 +102,7 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
     static final int EXIT_REASON_ROOT_TASK_VANISHED = 6;
     static final int EXIT_REASON_SCREEN_LOCKED = 7;
     static final int EXIT_REASON_SCREEN_LOCKED_SHOW_ON_TOP = 8;
+    static final int EXIT_REASON_CHILD_TASK_ENTER_PIP = 9;
     @IntDef(value = {
             EXIT_REASON_UNKNOWN,
             EXIT_REASON_APP_DOES_NOT_SUPPORT_MULTIWINDOW,
@@ -112,6 +113,7 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
             EXIT_REASON_ROOT_TASK_VANISHED,
             EXIT_REASON_SCREEN_LOCKED,
             EXIT_REASON_SCREEN_LOCKED_SHOW_ON_TOP,
+            EXIT_REASON_CHILD_TASK_ENTER_PIP,
     })
     @Retention(RetentionPolicy.SOURCE)
     @interface ExitReason{}
@@ -406,6 +408,8 @@ public class SplitScreenController implements DragAndDropPolicy.Starter,
                 return "APP_FINISHED";
             case EXIT_REASON_APP_DOES_NOT_SUPPORT_MULTIWINDOW:
                 return "APP_DOES_NOT_SUPPORT_MULTIWINDOW";
+            case EXIT_REASON_CHILD_TASK_ENTER_PIP:
+                return "CHILD_TASK_ENTER_PIP";
             default:
                 return "unknown reason, reason int = " + exitReason;
         }
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 e30e6c537c93..dd538dc4602c 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
@@ -35,6 +35,7 @@ import static com.android.wm.shell.splitscreen.SplitScreen.STAGE_TYPE_UNDEFINED;
 import static com.android.wm.shell.splitscreen.SplitScreen.stageTypeToString;
 import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_APP_DOES_NOT_SUPPORT_MULTIWINDOW;
 import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_APP_FINISHED;
+import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_CHILD_TASK_ENTER_PIP;
 import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_DEVICE_FOLDED;
 import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_DRAG_DIVIDER;
 import static com.android.wm.shell.splitscreen.SplitScreenController.EXIT_REASON_RETURN_HOME;
@@ -629,8 +630,12 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         });
         mShouldUpdateRecents = false;
 
-        mSideStage.removeAllTasks(wct, childrenToTop == mSideStage);
-        mMainStage.deactivate(wct, childrenToTop == mMainStage);
+        // When the exit split-screen is caused by one of the task enters auto pip,
+        // we want the tasks to be put to bottom instead of top, otherwise it will end up
+        // a fullscreen plus a pinned task instead of pinned only at the end of the transition.
+        final boolean fromEnteringPip = exitReason == EXIT_REASON_CHILD_TASK_ENTER_PIP;
+        mSideStage.removeAllTasks(wct, !fromEnteringPip && childrenToTop == mSideStage);
+        mMainStage.deactivate(wct, !fromEnteringPip && childrenToTop == mMainStage);
         mTaskOrganizer.applyTransaction(wct);
         mSyncQueue.runInSync(t -> t
                 .setWindowCrop(mMainStage.mRootLeash, null)
@@ -660,6 +665,8 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
             case EXIT_REASON_DRAG_DIVIDER:
             // Either of the split apps have finished
             case EXIT_REASON_APP_FINISHED:
+            // One of the children enters PiP
+            case EXIT_REASON_CHILD_TASK_ENTER_PIP:
                 return true;
             default:
                 return false;
@@ -749,6 +756,11 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         }
     }
 
+    private void onStageChildTaskEnterPip(StageListenerImpl stageListener, int taskId) {
+        exitSplitScreen(stageListener == mMainStageListener ? mMainStage : mSideStage,
+                EXIT_REASON_CHILD_TASK_ENTER_PIP);
+    }
+
     private void updateRecentTasksSplitPair() {
         if (!mShouldUpdateRecents) {
             return;
@@ -1437,6 +1449,11 @@ class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         }
 
         @Override
+        public void onChildTaskEnterPip(int taskId) {
+            StageCoordinator.this.onStageChildTaskEnterPip(this, taskId);
+        }
+
+        @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 cd10b9fde444..2c853c1c474c 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
@@ -20,6 +20,7 @@ import static android.app.ActivityTaskManager.INVALID_TASK_ID;
 import static android.app.WindowConfiguration.ACTIVITY_TYPE_STANDARD;
 import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.app.WindowConfiguration.WINDOWING_MODE_MULTI_WINDOW;
+import static android.app.WindowConfiguration.WINDOWING_MODE_PINNED;
 import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
 
 import static com.android.wm.shell.transition.Transitions.ENABLE_SHELL_TRANSITIONS;
@@ -73,6 +74,8 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
 
         void onChildTaskStatusChanged(int taskId, boolean present, boolean visible);
 
+        void onChildTaskEnterPip(int taskId);
+
         void onRootTaskVanished();
 
         void onNoLongerSupportMultiWindow();
@@ -256,6 +259,9 @@ class StageTaskListener implements ShellTaskOrganizer.TaskListener {
             mChildrenTaskInfo.remove(taskId);
             mChildrenLeashes.remove(taskId);
             mCallbacks.onChildTaskStatusChanged(taskId, false /* present */, taskInfo.isVisible);
+            if (taskInfo.getWindowingMode() == WINDOWING_MODE_PINNED) {
+                mCallbacks.onChildTaskEnterPip(taskId);
+            }
             if (ENABLE_SHELL_TRANSITIONS) {
                 // Status is managed/synchronized by the transition lifecycle.
                 return;