Implement swipe to delete on Recents Go

Introduce a ItemTouchHelper.Callback implementation that hooks up remove
logic to swiping right on task items. Additionally, tighten the
modification access to the task list in TaskListLoader so it is harder
to mis-use.

Bug: 114136250
Test: Removed app via swiping
Change-Id: I9b6e2783d1f6d56e655e9b7ffa9af85328f98159

go/quickstep/src/com/android/quickstep/TaskAdapter.java

@@ -25,7 +25,8 @@ import com.android.launcher3.R;
 import com.android.quickstep.views.TaskItemView;
 import com.android.systemui.shared.recents.model.Task;
 
-import java.util.ArrayList;
+import java.util.List;
+
 /**
  * Recycler view adapter that dynamically inflates and binds {@link TaskHolder} instances with the
  * appropriate {@link Task} from the recents task list.
@@ -56,7 +57,7 @@ public final class TaskAdapter extends Adapter<TaskHolder> {
 
     @Override
     public void onBindViewHolder(TaskHolder holder, int position) {
-        ArrayList<Task> tasks = mLoader.getCurrentTaskList();
+        List<Task> tasks = mLoader.getCurrentTaskList();
         if (position >= tasks.size()) {
             // Task list has updated.
             return;

go/quickstep/src/com/android/quickstep/TaskInputController.java

@@ -15,6 +15,7 @@
  */
 package com.android.quickstep;
 
+import com.android.systemui.shared.recents.model.Task;
 import com.android.systemui.shared.system.ActivityManagerWrapper;
 
 /**
@@ -22,9 +23,11 @@ import com.android.systemui.shared.system.ActivityManagerWrapper;
  */
 public final class TaskInputController {
 
-    TaskAdapter mAdapter;
+    private final TaskListLoader mLoader;
+    private final TaskAdapter mAdapter;
 
-    public TaskInputController(TaskAdapter adapter) {
+    public TaskInputController(TaskListLoader loader,TaskAdapter adapter) {
+        mLoader = loader;
         mAdapter = adapter;
     }
 
@@ -39,7 +42,14 @@ public final class TaskInputController {
                 null /* options */, null /* resultCallback */, null /* resultCallbackHandler */);
     }
 
-    // TODO: Implement swipe to delete and notify adapter that data has updated
+    public void onTaskSwiped(TaskHolder viewHolder) {
+        int position = viewHolder.getAdapterPosition();
+        Task task = viewHolder.getTask();
+        ActivityManagerWrapper.getInstance().removeTask(task.key.id);
+        mLoader.removeTask(task);
+        mAdapter.notifyItemRemoved(position);
+    }
 
     // TODO: Implement "Clear all" and notify adapter that data has updated
+
 }

go/quickstep/src/com/android/quickstep/TaskListLoader.java

@@ -24,6 +24,7 @@ import com.android.systemui.shared.recents.model.Task;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
 
@@ -45,13 +46,13 @@ public final class TaskListLoader {
 
     /**
      * Returns the current task list as of the last completed load (see
-     * {@link #loadTaskList}). This list of tasks is guaranteed to always have all its task
+     * {@link #loadTaskList}) as a read-only list. This list of tasks is guaranteed to always have
-     * content loaded.
+     * all its task content loaded.
      *
      * @return the current list of tasks w/ all content loaded
      */
-    public ArrayList<Task> getCurrentTaskList() {
+    public List<Task> getCurrentTaskList() {
-        return mTaskList;
+        return Collections.unmodifiableList(mTaskList);
     }
 
     /**
@@ -84,6 +85,13 @@ public final class TaskListLoader {
         });
     }
 
+    /**
+     * Removes the task from the current task list.
+     */
+    void removeTask(Task task) {
+        mTaskList.remove(task);
+    }
+
     /**
      * Loads task content for a list of tasks, including the label, icon, and thumbnail. For content
      * that isn't cached, load the content asynchronously in the background.

go/quickstep/src/com/android/quickstep/TaskSwipeCallback.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2019 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.quickstep;
+
+import static androidx.recyclerview.widget.ItemTouchHelper.RIGHT;
+
+import androidx.recyclerview.widget.ItemTouchHelper;
+import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.RecyclerView.ViewHolder;
+
+/**
+ * Callback for swipe input on {@link TaskHolder} views in the recents view.
+ */
+public final class TaskSwipeCallback extends ItemTouchHelper.SimpleCallback {
+
+    private final TaskInputController mTaskInputController;
+
+    public TaskSwipeCallback(TaskInputController inputController) {
+        super(0 /* dragDirs */, RIGHT);
+        mTaskInputController = inputController;
+    }
+
+    @Override
+    public boolean onMove(RecyclerView recyclerView, ViewHolder viewHolder,
+            ViewHolder target) {
+        return false;
+    }
+
+    @Override
+    public void onSwiped(ViewHolder viewHolder, int direction) {
+        if (direction == RIGHT) {
+            mTaskInputController.onTaskSwiped((TaskHolder) viewHolder);
+        }
+    }
+}

go/quickstep/src/com/android/quickstep/views/IconRecentsView.java

@@ -23,6 +23,7 @@ import android.util.FloatProperty;
 import android.view.ViewDebug;
 import android.widget.FrameLayout;
 
+import androidx.recyclerview.widget.ItemTouchHelper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 
@@ -30,6 +31,7 @@ import com.android.launcher3.R;
 import com.android.quickstep.TaskAdapter;
 import com.android.quickstep.TaskInputController;
 import com.android.quickstep.TaskListLoader;
+import com.android.quickstep.TaskSwipeCallback;
 
 /**
  * Root view for the icon recents view. Acts as the main interface to the rest of the Launcher code
@@ -76,29 +78,35 @@ public final class IconRecentsView extends FrameLayout {
     @ViewDebug.ExportedProperty(category = "launcher")
 
     private final Context mContext;
+    private final TaskListLoader mTaskLoader;
+    private final TaskAdapter mTaskAdapter;
+    private final TaskInputController mTaskInputController;
 
     private float mTranslationYFactor;
-    private TaskAdapter mTaskAdapter;
     private RecyclerView mTaskRecyclerView;
-    private TaskInputController mTaskInputController;
+
-    private TaskListLoader mTaskLoader;
 
     public IconRecentsView(Context context, AttributeSet attrs) {
         super(context, attrs);
         mContext = context;
+        mTaskLoader = new TaskListLoader(mContext);
+        mTaskAdapter = new TaskAdapter(mTaskLoader);
+        mTaskInputController = new TaskInputController(mTaskLoader, mTaskAdapter);
+        mTaskAdapter.setInputController(mTaskInputController);
     }
 
     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
-        mTaskLoader = new TaskListLoader(mContext);
+        if (mTaskRecyclerView == null) {
-        mTaskAdapter = new TaskAdapter(mTaskLoader);
-        mTaskInputController = new TaskInputController(mTaskAdapter);
-        mTaskAdapter.setInputController(mTaskInputController);
             mTaskRecyclerView = findViewById(R.id.recent_task_recycler_view);
             mTaskRecyclerView.setAdapter(mTaskAdapter);
             mTaskRecyclerView.setLayoutManager(
                     new LinearLayoutManager(mContext, VERTICAL, true /* reverseLayout */));
+            ItemTouchHelper helper = new ItemTouchHelper(
+                    new TaskSwipeCallback(mTaskInputController));
+            helper.attachToRecyclerView(mTaskRecyclerView);
+        }
     }
 
     /**