From 4e5fb2f4e1ed4eb119a201541ad89aafac8c53fe Mon Sep 17 00:00:00 2001
From: Winson Chung <winsonc@google.com>
Date: Tue, 15 Dec 2015 14:46:23 -0500
Subject: [PATCH] Allowing tasks to be swiped away in the history view.

Change-Id: Ide26856c291bcdd1b4ab5e15ae9eb876a9af719b
---
 .../android/systemui/recents/Constants.java   |   1 +
 .../systemui/recents/RecentsActivity.java     |   3 +-
 .../recents/events/ui/DismissTaskEvent.java   |  33 +++++
 .../history/RecentsHistoryAdapter.java        | 114 ++++++++++++++----
 .../RecentsHistoryItemTouchCallbacks.java     |  76 ++++++++++++
 .../recents/history/RecentsHistoryView.java   |  14 +--
 .../systemui/recents/model/TaskStack.java     |   9 +-
 .../systemui/recents/views/TaskStackView.java |   2 +
 8 files changed, 216 insertions(+), 36 deletions(-)
 create mode 100644 packages/SystemUI/src/com/android/systemui/recents/events/ui/DismissTaskEvent.java
 create mode 100644 packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryItemTouchCallbacks.java

diff --git a/packages/SystemUI/src/com/android/systemui/recents/Constants.java b/packages/SystemUI/src/com/android/systemui/recents/Constants.java
index c08fb0522b9bc..070b39594d340 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/Constants.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/Constants.java
@@ -27,6 +27,7 @@ public class Constants {
         public static final int DismissSourceKeyboard = 0;
         public static final int DismissSourceSwipeGesture = 1;
         public static final int DismissSourceHeaderButton = 2;
+        public static final int DismissSourceHistorySwipeGesture = 3;
     }
 
 }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java b/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
index ec963da3c1fdf..b3ce4a6e0d230 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
@@ -56,6 +56,7 @@ import com.android.systemui.recents.events.activity.ToggleRecentsEvent;
 import com.android.systemui.recents.events.component.RecentsVisibilityChangedEvent;
 import com.android.systemui.recents.events.component.ScreenPinningRequestEvent;
 import com.android.systemui.recents.events.ui.AllTaskViewsDismissedEvent;
+import com.android.systemui.recents.events.ui.DismissTaskEvent;
 import com.android.systemui.recents.events.ui.DismissTaskViewEvent;
 import com.android.systemui.recents.events.ui.ShowApplicationInfoEvent;
 import com.android.systemui.recents.events.ui.StackViewScrolledEvent;
@@ -726,7 +727,7 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
         MetricsLogger.count(this, "overview_app_info", 1);
     }
 
-    public final void onBusEvent(DismissTaskViewEvent event) {
+    public final void onBusEvent(DismissTaskEvent event) {
         // Remove any stored data from the loader
         RecentsTaskLoader loader = Recents.getTaskLoader();
         loader.deleteTaskData(event.task, false);
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/ui/DismissTaskEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/ui/DismissTaskEvent.java
new file mode 100644
index 0000000000000..bcbbde84a1602
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/ui/DismissTaskEvent.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2015 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.systemui.recents.events.ui;
+
+import com.android.systemui.recents.events.EventBus;
+import com.android.systemui.recents.model.Task;
+import com.android.systemui.recents.views.TaskView;
+
+/**
+ * This is sent when a {@link Task} has been dismissed.
+ */
+public class DismissTaskEvent extends EventBus.Event {
+
+    public final Task task;
+
+    public DismissTaskEvent(Task task) {
+        this.task = task;
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryAdapter.java b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryAdapter.java
index abe3c01f836f0..76439c0f6a67c 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryAdapter.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryAdapter.java
@@ -20,6 +20,7 @@ import android.app.ActivityOptions;
 import android.content.Context;
 import android.support.v7.widget.RecyclerView;
 import android.text.format.DateFormat;
+import android.util.SparseIntArray;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -27,9 +28,14 @@ import android.widget.ImageView;
 import android.widget.TextView;
 import com.android.systemui.R;
 import com.android.systemui.recents.Recents;
+import com.android.systemui.recents.events.EventBus;
+import com.android.systemui.recents.events.activity.HideHistoryButtonEvent;
+import com.android.systemui.recents.events.activity.HideHistoryEvent;
+import com.android.systemui.recents.misc.ReferenceCountedTrigger;
 import com.android.systemui.recents.misc.SystemServicesProxy;
 import com.android.systemui.recents.model.RecentsTaskLoader;
 import com.android.systemui.recents.model.Task;
+import com.android.systemui.recents.model.TaskStack;
 
 import java.util.ArrayList;
 import java.util.Calendar;
@@ -51,7 +57,7 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
     static final int TASK_ROW_VIEW_TYPE = 1;
 
     /**
-     * View holder implementation.  The {@param TaskCallbacks} are only called for TaskRow view
+     * View holder implementation. The {@param TaskCallbacks} are only called for TaskRow view
      * holders.
      */
     public static class ViewHolder extends RecyclerView.ViewHolder implements Task.TaskCallbacks {
@@ -85,14 +91,14 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
     /**
      * A single row of content.
      */
-    private interface Row {
+    interface Row {
         int getViewType();
     }
 
     /**
      * A date row.
      */
-    private static class DateRow implements Row {
+    static class DateRow implements Row {
 
         public final String date;
 
@@ -109,12 +115,14 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
     /**
      * A task row.
      */
-    private static class TaskRow implements Row, View.OnClickListener {
+    static class TaskRow implements Row, View.OnClickListener {
 
         public final Task task;
+        public final int dateKey;
 
-        public TaskRow(Task task) {
+        public TaskRow(Task task, int dateKey) {
             this.task = task;
+            this.dateKey = dateKey;
         }
 
         @Override
@@ -134,6 +142,8 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
     private LayoutInflater mLayoutInflater;
     private final List<Task> mTasks = new ArrayList<>();
     private final List<Row> mRows = new ArrayList<>();
+    private final SparseIntArray mTaskRowCount = new SparseIntArray();
+    private TaskStack mStack;
 
     public RecentsHistoryAdapter(Context context) {
         mLayoutInflater = LayoutInflater.from(context);
@@ -142,17 +152,17 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
     /**
      * Updates this adapter with the given tasks.
      */
-    public void updateTasks(Context context, List<Task> tasks) {
+    public void updateTasks(Context context, TaskStack stack) {
         mContext = context;
-        mTasks.clear();
-        mTasks.addAll(tasks);
+        mStack = stack;
 
         final Locale l = context.getResources().getConfiguration().locale;
         final String dateFormatStr = DateFormat.getBestDateTimePattern(l, "EEEEMMMMd");
-        final List<Task> tasksMostRecent = new ArrayList<>(tasks);
+        final List<Task> tasksMostRecent = new ArrayList<>(stack.getHistoricalTasks());
         Collections.reverse(tasksMostRecent);
-        int prevDayKey = -1;
+        int prevDateKey = -1;
         mRows.clear();
+        mTaskRowCount.clear();
         for (Task task : tasksMostRecent) {
             if (task.isFreeformTask()) {
                 continue;
@@ -160,34 +170,46 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
 
             Calendar cal = Calendar.getInstance(l);
             cal.setTimeInMillis(task.key.lastActiveTime);
-            int dayKey = Objects.hash(cal.get(Calendar.YEAR), cal.get(Calendar.DAY_OF_YEAR));
-            if (dayKey != prevDayKey) {
-                prevDayKey = dayKey;
+            int dateKey = Objects.hash(cal.get(Calendar.YEAR), cal.get(Calendar.DAY_OF_YEAR));
+            if (dateKey != prevDateKey) {
+                prevDateKey = dateKey;
                 mRows.add(new DateRow(DateFormat.format(dateFormatStr, cal).toString()));
             }
-            mRows.add(new TaskRow(task));
+            mRows.add(new TaskRow(task, dateKey));
+            mTaskRowCount.put(dateKey, mTaskRowCount.get(dateKey, 0) + 1);
         }
         notifyDataSetChanged();
     }
 
     /**
-     * Removes historical tasks beloning to the specified package and user.
+     * Removes historical tasks belonging to the specified package and user. We do not need to
+     * remove the task from the TaskStack since the TaskStackView will also receive this event.
      */
     public void removeTasks(String packageName, int userId) {
         boolean packagesRemoved = false;
-        for (int i = mTasks.size() - 1; i >= 0; i--) {
-            Task task = mTasks.get(i);
-            String taskPackage = task.key.getComponent().getPackageName();
-            if (task.key.userId == userId && taskPackage.equals(packageName)) {
-                mTasks.remove(i);
-                packagesRemoved = true;
+        for (int i = mRows.size() - 1; i >= 0; i--) {
+            Row row = mRows.get(i);
+            if (row.getViewType() == TASK_ROW_VIEW_TYPE) {
+                TaskRow taskRow = (TaskRow) row;
+                Task task = taskRow.task;
+                String taskPackage = task.key.getComponent().getPackageName();
+                if (task.key.userId == userId && taskPackage.equals(packageName)) {
+                    i = removeTaskRow(i);
+                }
             }
         }
-        if (packagesRemoved) {
-            updateTasks(mContext, new ArrayList<Task>(mTasks));
+        if (mRows.isEmpty()) {
+            dismissHistory();
         }
     }
 
+    /**
+     * Returns the row at the given {@param position}.
+     */
+    public Row getRow(int position) {
+        return mRows.get(position);
+    }
+
     @Override
     public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
         switch (viewType) {
@@ -242,6 +264,16 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
         }
     }
 
+    public void onTaskRemoved(Task task, int position) {
+        // Since this is removed from the history, we need to update the stack as well to ensure
+        // that the model is correct
+        mStack.removeTask(task);
+        removeTaskRow(position);
+        if (mRows.isEmpty()) {
+            dismissHistory();
+        }
+    }
+
     @Override
     public int getItemCount() {
         return mRows.size();
@@ -251,4 +283,40 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
     public int getItemViewType(int position) {
         return mRows.get(position).getViewType();
     }
+
+    /**
+     * Removes a task row, also removing the associated {@link DateRow} if there are no more tasks
+     * in that date group.
+     *
+     * @param position an adapter position of a task row such that 0 < position < num rows.
+     * @return the index of the last removed row
+     */
+    private int removeTaskRow(int position) {
+        // Remove the task at that row
+        TaskRow taskRow = (TaskRow) mRows.remove(position);
+        int numTasks = mTaskRowCount.get(taskRow.dateKey) - 1;
+        mTaskRowCount.put(taskRow.dateKey, numTasks);
+        notifyItemRemoved(position);
+
+        if (numTasks == 0) {
+            // If that was the last task row in the group, then remove the date as well
+            mRows.remove(position - 1);
+            mTaskRowCount.removeAt(mTaskRowCount.indexOfKey(taskRow.dateKey));
+            notifyItemRemoved(position - 1);
+            return position - 1;
+        } else {
+            return position;
+        }
+    }
+
+    /**
+     * Dismisses history back to the stack view.
+     */
+    private void dismissHistory() {
+        ReferenceCountedTrigger t = new ReferenceCountedTrigger(mContext);
+        t.increment();
+        EventBus.getDefault().send(new HideHistoryEvent(true /* animate */, t));
+        t.decrement();
+        EventBus.getDefault().send(new HideHistoryButtonEvent());
+    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryItemTouchCallbacks.java b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryItemTouchCallbacks.java
new file mode 100644
index 0000000000000..e0a27308dd1a2
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryItemTouchCallbacks.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2015 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.systemui.recents.history;
+
+import android.content.Context;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.helper.ItemTouchHelper;
+import com.android.internal.logging.MetricsLogger;
+import com.android.systemui.recents.Constants;
+import com.android.systemui.recents.events.EventBus;
+import com.android.systemui.recents.events.ui.DismissTaskEvent;
+
+
+/**
+ * An item touch handler for items in the history view.
+ */
+public class RecentsHistoryItemTouchCallbacks extends ItemTouchHelper.SimpleCallback {
+
+    private Context mContext;
+    private RecentsHistoryAdapter mAdapter;
+
+    public RecentsHistoryItemTouchCallbacks(Context context, RecentsHistoryAdapter adapter) {
+        super(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT);
+        mContext = context;
+        mAdapter = adapter;
+    }
+
+    @Override
+    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder,
+            RecyclerView.ViewHolder target) {
+        return false;
+    }
+
+    @Override
+    public int getSwipeDirs(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
+        int viewType = mAdapter.getItemViewType(viewHolder.getAdapterPosition());
+        switch (viewType) {
+            case RecentsHistoryAdapter.DATE_ROW_VIEW_TYPE:
+                // Disallow swiping
+                return 0;
+            default:
+                return super.getSwipeDirs(recyclerView, viewHolder);
+        }
+    }
+
+    @Override
+    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
+        int position = viewHolder.getAdapterPosition();
+        if (position != RecyclerView.NO_POSITION) {
+            RecentsHistoryAdapter.Row row = mAdapter.getRow(position);
+            RecentsHistoryAdapter.TaskRow taskRow = (RecentsHistoryAdapter.TaskRow) row;
+
+            // Remove the task from the system
+            EventBus.getDefault().send(new DismissTaskEvent(taskRow.task));
+            mAdapter.onTaskRemoved(taskRow.task, position);
+
+            // Keep track of deletions by swiping within history
+            MetricsLogger.histogram(mContext, "overview_task_dismissed_source",
+                    Constants.Metrics.DismissSourceHistorySwipeGesture);
+        }
+    }
+}
diff --git a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryView.java b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryView.java
index 1163f143432e3..9524da5d08bb8 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryView.java
@@ -16,12 +16,12 @@
 
 package com.android.systemui.recents.history;
 
-import android.content.ComponentName;
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Rect;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.helper.ItemTouchHelper;
 import android.util.AttributeSet;
 import android.view.View;
 import android.view.WindowInsets;
@@ -36,12 +36,7 @@ import com.android.systemui.recents.events.EventBus;
 import com.android.systemui.recents.events.activity.PackagesChangedEvent;
 import com.android.systemui.recents.misc.ReferenceCountedTrigger;
 import com.android.systemui.recents.misc.SystemServicesProxy;
-import com.android.systemui.recents.model.Task;
 import com.android.systemui.recents.model.TaskStack;
-import com.android.systemui.recents.views.TaskView;
-
-import java.util.ArrayList;
-import java.util.HashSet;
 
 /**
  * A list of the recent tasks that are not in the stack.
@@ -53,6 +48,7 @@ public class RecentsHistoryView extends LinearLayout {
 
     private RecyclerView mRecyclerView;
     private RecentsHistoryAdapter mAdapter;
+    private RecentsHistoryItemTouchCallbacks mItemTouchHandler;
     private boolean mIsVisible;
     private Rect mSystemInsets = new Rect();
 
@@ -77,6 +73,7 @@ public class RecentsHistoryView extends LinearLayout {
         super(context, attrs, defStyleAttr, defStyleRes);
         Resources res = context.getResources();
         mAdapter = new RecentsHistoryAdapter(context);
+        mItemTouchHandler = new RecentsHistoryItemTouchCallbacks(context, mAdapter);
         mHistoryTransitionDuration = res.getInteger(R.integer.recents_history_transition_duration);
         mFastOutSlowInInterpolator = AnimationUtils.loadInterpolator(context,
                 com.android.internal.R.interpolator.fast_out_slow_in);
@@ -101,7 +98,7 @@ public class RecentsHistoryView extends LinearLayout {
                         .start();
             }
         });
-        mAdapter.updateTasks(getContext(), stack.getHistoricalTasks());
+        mAdapter.updateTasks(getContext(), stack);
         mIsVisible = true;
     }
 
@@ -156,6 +153,8 @@ public class RecentsHistoryView extends LinearLayout {
         mRecyclerView = (RecyclerView) findViewById(R.id.list);
         mRecyclerView.setAdapter(mAdapter);
         mRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
+        ItemTouchHelper touchHelper = new ItemTouchHelper(mItemTouchHandler);
+        touchHelper.attachToRecyclerView(mRecyclerView);
     }
 
     @Override
@@ -180,7 +179,6 @@ public class RecentsHistoryView extends LinearLayout {
 
     @Override
     protected void onAttachedToWindow() {
-        SystemServicesProxy ssp = Recents.getSystemServices();
         EventBus.getDefault().register(this, RecentsActivity.EVENT_BUS_PRIORITY + 1);
         super.onAttachedToWindow();
     }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java b/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java
index 69a94fee95506..6e6cef792ae19 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/model/TaskStack.java
@@ -407,9 +407,11 @@ public class TaskStack {
         taskList.remove(t);
         // Remove it from the group as well, and if it is empty, remove the group
         TaskGrouping group = t.group;
-        group.removeTask(t);
-        if (group.getTaskCount() == 0) {
-            removeGroup(group);
+        if (group != null) {
+            group.removeTask(t);
+            if (group.getTaskCount() == 0) {
+                removeGroup(group);
+            }
         }
         // Update the lock-to-app state
         t.lockToThisTask = false;
@@ -419,7 +421,6 @@ public class TaskStack {
     public void removeTask(Task t) {
         if (mStackTaskList.contains(t)) {
             boolean wasFrontMostTask = (getStackFrontMostTask() == t);
-            int removedTaskIndex = indexOfStackTask(t);
             removeTaskImpl(mStackTaskList, t);
             Task newFrontMostTask = getStackFrontMostTask();
             if (newFrontMostTask != null && newFrontMostTask.lockToTaskEnabled) {
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java
index 4140fb576bcdb..b9ca9fd5a5b55 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java
@@ -57,6 +57,7 @@ import com.android.systemui.recents.events.activity.ShowHistoryButtonEvent;
 import com.android.systemui.recents.events.activity.ShowHistoryEvent;
 import com.android.systemui.recents.events.component.RecentsVisibilityChangedEvent;
 import com.android.systemui.recents.events.ui.AllTaskViewsDismissedEvent;
+import com.android.systemui.recents.events.ui.DismissTaskEvent;
 import com.android.systemui.recents.events.ui.DismissTaskViewEvent;
 import com.android.systemui.recents.events.ui.StackViewScrolledEvent;
 import com.android.systemui.recents.events.ui.UpdateFreeformTaskViewVisibilityEvent;
@@ -1430,6 +1431,7 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
 
     public final void onBusEvent(DismissTaskViewEvent event) {
         removeTaskViewFromStack(event.taskView);
+        EventBus.getDefault().send(new DismissTaskEvent(event.task));
     }
 
     public final void onBusEvent(FocusNextTaskViewEvent event) {