Allow TaskFragment to move to bottom when clear top

Add TaskFragment op OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH
If set to true, when a launching activity clears top, the TaskFragment
is moved bottom of the Task instead of being finished.

Bug: 317896352
Test: atest TaskTests
Change-Id: I4c7e11f82fd26adda20233f6dfd954beb896c72b

5 files changed, 150 insertions, 4 deletions

diff --git a/core/java/android/window/TaskFragmentOperation.java b/core/java/android/window/TaskFragmentOperation.java
index acc6a749e9b7..7b8cdff8e20b 100644
--- a/core/java/android/window/TaskFragmentOperation.java
+++ b/core/java/android/window/TaskFragmentOperation.java
@@ -125,6 +125,16 @@ public final class TaskFragmentOperation implements Parcelable {
      */
     public static final int OP_TYPE_SET_DIM_ON_TASK = 16;
 
+    /**
+     * Sets this TaskFragment to move to bottom of the Task if any of the activities below it is
+     * launched in a mode requiring clear top.
+     *
+     * This is only allowed for system organizers. See
+     * {@link com.android.server.wm.TaskFragmentOrganizerController#registerOrganizer(
+     * ITaskFragmentOrganizer, boolean)}
+     */
+    public static final int OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH = 17;
+
     @IntDef(prefix = { "OP_TYPE_" }, value = {
             OP_TYPE_UNKNOWN,
             OP_TYPE_CREATE_TASK_FRAGMENT,
@@ -144,6 +154,7 @@ public final class TaskFragmentOperation implements Parcelable {
             OP_TYPE_CREATE_TASK_FRAGMENT_DECOR_SURFACE,
             OP_TYPE_REMOVE_TASK_FRAGMENT_DECOR_SURFACE,
             OP_TYPE_SET_DIM_ON_TASK,
+            OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH,
     })
     @Retention(RetentionPolicy.SOURCE)
     public @interface OperationType {}
@@ -173,12 +184,14 @@ public final class TaskFragmentOperation implements Parcelable {
 
     private final boolean mDimOnTask;
 
+    private final boolean mMoveToBottomIfClearWhenLaunch;
+
     private TaskFragmentOperation(@OperationType int opType,
             @Nullable TaskFragmentCreationParams taskFragmentCreationParams,
             @Nullable IBinder activityToken, @Nullable Intent activityIntent,
             @Nullable Bundle bundle, @Nullable IBinder secondaryFragmentToken,
             @Nullable TaskFragmentAnimationParams animationParams,
-            boolean isolatedNav, boolean dimOnTask) {
+            boolean isolatedNav, boolean dimOnTask, boolean moveToBottomIfClearWhenLaunch) {
         mOpType = opType;
         mTaskFragmentCreationParams = taskFragmentCreationParams;
         mActivityToken = activityToken;
@@ -188,6 +201,7 @@ public final class TaskFragmentOperation implements Parcelable {
         mAnimationParams = animationParams;
         mIsolatedNav = isolatedNav;
         mDimOnTask = dimOnTask;
+        mMoveToBottomIfClearWhenLaunch = moveToBottomIfClearWhenLaunch;
     }
 
     private TaskFragmentOperation(Parcel in) {
@@ -200,6 +214,7 @@ public final class TaskFragmentOperation implements Parcelable {
         mAnimationParams = in.readTypedObject(TaskFragmentAnimationParams.CREATOR);
         mIsolatedNav = in.readBoolean();
         mDimOnTask = in.readBoolean();
+        mMoveToBottomIfClearWhenLaunch = in.readBoolean();
     }
 
     @Override
@@ -213,6 +228,7 @@ public final class TaskFragmentOperation implements Parcelable {
         dest.writeTypedObject(mAnimationParams, flags);
         dest.writeBoolean(mIsolatedNav);
         dest.writeBoolean(mDimOnTask);
+        dest.writeBoolean(mMoveToBottomIfClearWhenLaunch);
     }
 
     @NonNull
@@ -300,6 +316,14 @@ public final class TaskFragmentOperation implements Parcelable {
         return mDimOnTask;
     }
 
+    /**
+     * Returns whether the TaskFragment should move to bottom of task when any activity below it
+     * is launched in clear top mode.
+     */
+    public boolean isMoveToBottomIfClearWhenLaunch() {
+        return mMoveToBottomIfClearWhenLaunch;
+    }
+
     @Override
     public String toString() {
         final StringBuilder sb = new StringBuilder();
@@ -324,6 +348,7 @@ public final class TaskFragmentOperation implements Parcelable {
         }
         sb.append(", isolatedNav=").append(mIsolatedNav);
         sb.append(", dimOnTask=").append(mDimOnTask);
+        sb.append(", moveToBottomIfClearWhenLaunch=").append(mMoveToBottomIfClearWhenLaunch);
 
         sb.append('}');
         return sb.toString();
@@ -332,7 +357,8 @@ public final class TaskFragmentOperation implements Parcelable {
     @Override
     public int hashCode() {
         return Objects.hash(mOpType, mTaskFragmentCreationParams, mActivityToken, mActivityIntent,
-                mBundle, mSecondaryFragmentToken, mAnimationParams, mIsolatedNav, mDimOnTask);
+                mBundle, mSecondaryFragmentToken, mAnimationParams, mIsolatedNav, mDimOnTask,
+                mMoveToBottomIfClearWhenLaunch);
     }
 
     @Override
@@ -349,7 +375,8 @@ public final class TaskFragmentOperation implements Parcelable {
                 && Objects.equals(mSecondaryFragmentToken, other.mSecondaryFragmentToken)
                 && Objects.equals(mAnimationParams, other.mAnimationParams)
                 && mIsolatedNav == other.mIsolatedNav
-                && mDimOnTask == other.mDimOnTask;
+                && mDimOnTask == other.mDimOnTask
+                && mMoveToBottomIfClearWhenLaunch == other.mMoveToBottomIfClearWhenLaunch;
     }
 
     @Override
@@ -385,6 +412,8 @@ public final class TaskFragmentOperation implements Parcelable {
 
         private boolean mDimOnTask;
 
+        private boolean mMoveToBottomIfClearWhenLaunch;
+
         /**
          * @param opType the {@link OperationType} of this {@link TaskFragmentOperation}.
          */
@@ -466,13 +495,23 @@ public final class TaskFragmentOperation implements Parcelable {
         }
 
         /**
+         * Sets whether the TaskFragment should move to bottom of task when any activity below it
+         * is launched in clear top mode.
+         */
+        @NonNull
+        public Builder setMoveToBottomIfClearWhenLaunch(boolean moveToBottomIfClearWhenLaunch) {
+            mMoveToBottomIfClearWhenLaunch = moveToBottomIfClearWhenLaunch;
+            return this;
+        }
+
+        /**
          * Constructs the {@link TaskFragmentOperation}.
          */
         @NonNull
         public TaskFragmentOperation build() {
             return new TaskFragmentOperation(mOpType, mTaskFragmentCreationParams, mActivityToken,
                     mActivityIntent, mBundle, mSecondaryFragmentToken, mAnimationParams,
-                    mIsolatedNav, mDimOnTask);
+                    mIsolatedNav, mDimOnTask, mMoveToBottomIfClearWhenLaunch);
         }
     }
 }
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index a7a6bf2ed2a1..314d720692f7 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -208,6 +208,7 @@ import java.io.PrintWriter;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
+import java.util.List;
 import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
@@ -1702,6 +1703,8 @@ class Task extends TaskFragment {
         final ActivityRecord r = findActivityInHistory(newR.mActivityComponent, newR.mUserId);
         if (r == null) return null;
 
+        moveTaskFragmentsToBottomIfNeeded(r, finishCount);
+
         final PooledPredicate f = PooledLambda.obtainPredicate(
                 (ActivityRecord ar, ActivityRecord boundaryActivity) ->
                         finishActivityAbove(ar, boundaryActivity, finishCount),
@@ -1722,6 +1725,50 @@ class Task extends TaskFragment {
         return r;
     }
 
+    /**
+     * Moves {@link TaskFragment}s to the bottom if the flag
+     * {@link TaskFragment#isMoveToBottomIfClearWhenLaunch} is {@code true}.
+     */
+    @VisibleForTesting
+    void moveTaskFragmentsToBottomIfNeeded(@NonNull ActivityRecord r, @NonNull int[] finishCount) {
+        final int activityIndex = mChildren.indexOf(r);
+        if (activityIndex < 0) {
+            return;
+        }
+
+        List<TaskFragment> taskFragmentsToMove = null;
+
+        // Find the TaskFragments that need to be moved
+        for (int i = mChildren.size() - 1; i > activityIndex; i--) {
+            final TaskFragment taskFragment = mChildren.get(i).asTaskFragment();
+            if (taskFragment != null && taskFragment.isMoveToBottomIfClearWhenLaunch()) {
+                if (taskFragmentsToMove == null) {
+                    taskFragmentsToMove = new ArrayList<>();
+                }
+                taskFragmentsToMove.add(taskFragment);
+            }
+        }
+        if (taskFragmentsToMove == null) {
+            return;
+        }
+
+        // Move the TaskFragments to the bottom of the Task. Their relative orders are preserved.
+        final int size = taskFragmentsToMove.size();
+        for (int i = 0; i < size; i++) {
+            final TaskFragment taskFragment = taskFragmentsToMove.get(i);
+
+            // The visibility of the TaskFragment may change. Collect it in the transition so that
+            // transition animation can be properly played.
+            mTransitionController.collect(taskFragment);
+
+            positionChildAt(POSITION_BOTTOM, taskFragment, false /* includeParents */);
+        }
+
+        // Treat it as if the TaskFragments are finished so that a transition animation can be
+        // played to send the TaskFragments back and bring the activity to front.
+        finishCount[0] += size;
+    }
+
     private static boolean finishActivityAbove(ActivityRecord r, ActivityRecord boundaryActivity,
             @NonNull int[] finishCount) {
         // Stop operation once we reach the boundary activity.
diff --git a/services/core/java/com/android/server/wm/TaskFragment.java b/services/core/java/com/android/server/wm/TaskFragment.java
index f56759f9481c..7d418eae6548 100644
--- a/services/core/java/com/android/server/wm/TaskFragment.java
+++ b/services/core/java/com/android/server/wm/TaskFragment.java
@@ -363,6 +363,12 @@ class TaskFragment extends WindowContainer<WindowContainer> {
      */
     private boolean mIsolatedNav;
 
+    /**
+     * Whether the TaskFragment should move to bottom of task when any activity below it is
+     * launched in clear top mode.
+     */
+    private boolean mMoveToBottomIfClearWhenLaunch;
+
     /** When set, will force the task to report as invisible. */
     static final int FLAG_FORCE_HIDDEN_FOR_PINNED_TASK = 1;
     static final int FLAG_FORCE_HIDDEN_FOR_TASK_ORG = 1 << 1;
@@ -3045,6 +3051,14 @@ class TaskFragment extends WindowContainer<WindowContainer> {
         mEmbeddedDimArea = embeddedDimArea;
     }
 
+    void setMoveToBottomIfClearWhenLaunch(boolean moveToBottomIfClearWhenLaunch) {
+        mMoveToBottomIfClearWhenLaunch = moveToBottomIfClearWhenLaunch;
+    }
+
+    boolean isMoveToBottomIfClearWhenLaunch() {
+        return mMoveToBottomIfClearWhenLaunch;
+    }
+
     @VisibleForTesting
     boolean isDimmingOnParentTask() {
         return mEmbeddedDimArea == EMBEDDED_DIM_AREA_PARENT_TASK;
diff --git a/services/core/java/com/android/server/wm/WindowOrganizerController.java b/services/core/java/com/android/server/wm/WindowOrganizerController.java
index 59d0210251d1..cb291f0868d8 100644
--- a/services/core/java/com/android/server/wm/WindowOrganizerController.java
+++ b/services/core/java/com/android/server/wm/WindowOrganizerController.java
@@ -36,6 +36,7 @@ import static android.window.TaskFragmentOperation.OP_TYPE_SET_ANIMATION_PARAMS;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_COMPANION_TASK_FRAGMENT;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_DIM_ON_TASK;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_ISOLATED_NAVIGATION;
+import static android.window.TaskFragmentOperation.OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH;
 import static android.window.TaskFragmentOperation.OP_TYPE_SET_RELATIVE_BOUNDS;
 import static android.window.TaskFragmentOperation.OP_TYPE_START_ACTIVITY_IN_TASK_FRAGMENT;
 import static android.window.TaskFragmentOperation.OP_TYPE_UNKNOWN;
@@ -1502,6 +1503,11 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
                         : EMBEDDED_DIM_AREA_TASK_FRAGMENT);
                 break;
             }
+            case OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH: {
+                taskFragment.setMoveToBottomIfClearWhenLaunch(
+                        operation.isMoveToBottomIfClearWhenLaunch());
+                break;
+            }
         }
         return effects;
     }
@@ -1554,6 +1560,17 @@ class WindowOrganizerController extends IWindowOrganizerController.Stub
             return false;
         }
 
+        if ((opType == OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH)
+                && !mTaskFragmentOrganizerController.isSystemOrganizer(organizer.asBinder())) {
+            final Throwable exception = new SecurityException(
+                    "Only a system organizer can perform "
+                            + "OP_TYPE_SET_MOVE_TO_BOTTOM_IF_CLEAR_WHEN_LAUNCH."
+            );
+            sendTaskFragmentOperationFailure(organizer, errorCallbackToken, taskFragment,
+                    opType, exception);
+            return false;
+        }
+
         final IBinder secondaryFragmentToken = operation.getSecondaryFragmentToken();
         return secondaryFragmentToken == null
                 || validateTaskFragment(mLaunchTaskFragments.get(secondaryFragmentToken), opType,
diff --git a/services/tests/wmtests/src/com/android/server/wm/TaskTests.java b/services/tests/wmtests/src/com/android/server/wm/TaskTests.java
index b36080023ef2..961fdfb14bf3 100644
--- a/services/tests/wmtests/src/com/android/server/wm/TaskTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/TaskTests.java
@@ -1822,6 +1822,35 @@ public class TaskTests extends WindowTestsBase {
         verify(fragment2).assignLayer(t, 2);
     }
 
+    @Test
+    public void testMoveTaskFragmentsToBottomIfNeeded() {
+        final TaskFragmentOrganizer organizer = new TaskFragmentOrganizer(Runnable::run);
+        final Task task = new TaskBuilder(mSupervisor).setCreateActivity(true).build();
+        final ActivityRecord unembeddedActivity = task.getTopMostActivity();
+
+        final TaskFragment fragment1 = createTaskFragmentWithEmbeddedActivity(task, organizer);
+        final TaskFragment fragment2 = createTaskFragmentWithEmbeddedActivity(task, organizer);
+        final TaskFragment fragment3 = createTaskFragmentWithEmbeddedActivity(task, organizer);
+        doReturn(true).when(fragment1).isMoveToBottomIfClearWhenLaunch();
+        doReturn(false).when(fragment2).isMoveToBottomIfClearWhenLaunch();
+        doReturn(true).when(fragment3).isMoveToBottomIfClearWhenLaunch();
+
+        assertEquals(unembeddedActivity, task.mChildren.get(0));
+        assertEquals(fragment1, task.mChildren.get(1));
+        assertEquals(fragment2, task.mChildren.get(2));
+        assertEquals(fragment3, task.mChildren.get(3));
+
+        final int[] finishCount = {0};
+        task.moveTaskFragmentsToBottomIfNeeded(unembeddedActivity, finishCount);
+
+        // fragment1 and fragment3 should be moved to the bottom of the task
+        assertEquals(fragment1, task.mChildren.get(0));
+        assertEquals(fragment3, task.mChildren.get(1));
+        assertEquals(unembeddedActivity, task.mChildren.get(2));
+        assertEquals(fragment2, task.mChildren.get(3));
+        assertEquals(2, finishCount[0]);
+    }
+
     private Task getTestTask() {
         return new TaskBuilder(mSupervisor).setCreateActivity(true).build();
     }