From 49df4209cf8a3ee6cf8e09edc14675028a4b1862 Mon Sep 17 00:00:00 2001
From: Winson <winsonc@google.com>
Date: Mon, 25 Jan 2016 17:33:34 -0800
Subject: [PATCH] Part 1: Tweaking history transition to match design.

- Adding background scrim that can be controlled across transitions
  within recents.  As a result, we can remove the status bar scrim.
- Moving the history view into the RecentsView now that it animates in
  parallel with the task stack
- Transition home from history no longer goes back to stack view first
- Removing some extra allocations when going into history and loading
  tasks

Change-Id: I665baefcdd619de5e9366923eaaf4c558261141a
---
 packages/SystemUI/res/drawable/ic_history.xml |  28 ++
 packages/SystemUI/res/layout/recents.xml      |  14 -
 .../SystemUI/res/layout/recents_empty.xml     |   1 -
 .../SystemUI/res/layout/recents_history.xml   |   1 -
 .../res/layout/recents_history_button.xml     |  17 +-
 .../res/layout/recents_history_date.xml       |   6 +-
 .../res/layout/recents_history_task.xml       |   4 +-
 packages/SystemUI/res/values/strings.xml      |   4 +-
 packages/SystemUI/res/values/styles.xml       |   2 +-
 .../systemui/recents/RecentsActivity.java     |  87 +++---
 .../events/activity/HideHistoryEvent.java     |   2 +-
 .../activity/ShowHistoryButtonEvent.java      |   8 +-
 .../events/activity/ShowHistoryEvent.java     |   2 +-
 .../events/activity/ToggleHistoryEvent.java   |  28 ++
 .../events/ui/ResetBackgroundScrimEvent.java  |  26 ++
 .../events/ui/UpdateBackgroundScrimEvent.java |  31 ++
 .../history/RecentsHistoryAdapter.java        |   6 +-
 .../recents/history/RecentsHistoryView.java   |  69 +++--
 .../recents/model/RecentsTaskLoadPlan.java    |   5 +-
 .../recents/views/AnimateableViewBounds.java  |  25 +-
 .../systemui/recents/views/RecentsView.java   | 293 +++++++++++++-----
 .../recents/views/SystemBarScrimViews.java    |  35 +--
 .../views/TaskStackAnimationHelper.java       |  47 ++-
 .../views/TaskStackLayoutAlgorithm.java       |   1 +
 .../systemui/recents/views/TaskStackView.java |  44 ++-
 .../recents/views/TaskViewAnimation.java      |   4 +
 26 files changed, 534 insertions(+), 256 deletions(-)
 create mode 100644 packages/SystemUI/res/drawable/ic_history.xml
 create mode 100644 packages/SystemUI/src/com/android/systemui/recents/events/activity/ToggleHistoryEvent.java
 create mode 100644 packages/SystemUI/src/com/android/systemui/recents/events/ui/ResetBackgroundScrimEvent.java
 create mode 100644 packages/SystemUI/src/com/android/systemui/recents/events/ui/UpdateBackgroundScrimEvent.java

diff --git a/packages/SystemUI/res/drawable/ic_history.xml b/packages/SystemUI/res/drawable/ic_history.xml
new file mode 100644
index 0000000000000..e936864f82ab5
--- /dev/null
+++ b/packages/SystemUI/res/drawable/ic_history.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+     Copyright (C) 2016 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.
+-->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+
+    <path
+        android:fillColor="#FFFFFF"
+        android:pathData="M13 3c-4.97 0-9 4.03-9 9H1l3.89 3.89 .07 .14L9 12H6c0-3.87 3.13-7 7-7s7 3.13 7
+7-3.13 7-7 7c-1.93 0-3.68-.79-4.94-2.06l-1.42 1.42C8.27 19.99 10.51 21 13
+21c4.97 0 9-4.03 9-9s-4.03-9-9-9zm-1 5v5l4.28 2.54 .72 -1.21-3.5-2.08V8H12z" />
+</vector>
\ No newline at end of file
diff --git a/packages/SystemUI/res/layout/recents.xml b/packages/SystemUI/res/layout/recents.xml
index 16ff14cdb331f..186aaf6b40e80 100644
--- a/packages/SystemUI/res/layout/recents.xml
+++ b/packages/SystemUI/res/layout/recents.xml
@@ -17,14 +17,6 @@
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent">
-    <!-- Status Bar Scrim View -->
-    <ImageView
-        android:id="@+id/status_bar_scrim"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:layout_gravity="center_horizontal|top"
-        android:scaleType="fitXY"
-        android:src="@drawable/recents_status_gradient" />
 
     <!-- Recents View -->
     <com.android.systemui.recents.views.RecentsView
@@ -33,12 +25,6 @@
         android:layout_height="match_parent">
     </com.android.systemui.recents.views.RecentsView>
 
-    <!-- History View -->
-    <ViewStub android:id="@+id/history_view_stub"
-           android:layout="@layout/recents_history"
-           android:layout_width="match_parent"
-           android:layout_height="match_parent" />
-
     <!-- Nav Bar Scrim View -->
     <ImageView
         android:id="@+id/nav_bar_scrim"
diff --git a/packages/SystemUI/res/layout/recents_empty.xml b/packages/SystemUI/res/layout/recents_empty.xml
index 4b68e77ca41d3..b2c03312c9d1f 100644
--- a/packages/SystemUI/res/layout/recents_empty.xml
+++ b/packages/SystemUI/res/layout/recents_empty.xml
@@ -24,5 +24,4 @@
     android:textColor="#ffffffff"
     android:text="@string/recents_empty_message"
     android:fontFamily="sans-serif"
-    android:background="#80000000"
     android:visibility="gone" />
\ No newline at end of file
diff --git a/packages/SystemUI/res/layout/recents_history.xml b/packages/SystemUI/res/layout/recents_history.xml
index b65a5c58f6c73..dc2da7270eb87 100644
--- a/packages/SystemUI/res/layout/recents_history.xml
+++ b/packages/SystemUI/res/layout/recents_history.xml
@@ -17,7 +17,6 @@
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:background="#99000000"
     android:orientation="vertical">
     <android.support.v7.widget.RecyclerView
         android:id="@+id/list"
diff --git a/packages/SystemUI/res/layout/recents_history_button.xml b/packages/SystemUI/res/layout/recents_history_button.xml
index 8c96fc6839f8e..538bad1fcf1ea 100644
--- a/packages/SystemUI/res/layout/recents_history_button.xml
+++ b/packages/SystemUI/res/layout/recents_history_button.xml
@@ -15,15 +15,24 @@
 -->
 <TextView
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
+    android:id="@+id/button"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
     android:gravity="start|center_vertical"
-    android:text="@string/recents_show_history_button_label"
+    android:paddingStart="14dp"
+    android:paddingEnd="14dp"
+    android:paddingTop="12dp"
+    android:paddingBottom="12dp"
+    android:text="@string/recents_history_button_label"
     android:textSize="14sp"
     android:textColor="#FFFFFF"
     android:textAllCaps="true"
+    android:drawableStart="@drawable/ic_history"
+    android:drawablePadding="6dp"
     android:shadowColor="#99000000"
     android:shadowDx="0"
     android:shadowDy="2"
     android:shadowRadius="5"
-    android:fontFamily="sans-serif-medium" />
\ No newline at end of file
+    android:fontFamily="sans-serif-medium"
+    android:background="?android:selectableItemBackground"
+    android:visibility="invisible" />
diff --git a/packages/SystemUI/res/layout/recents_history_date.xml b/packages/SystemUI/res/layout/recents_history_date.xml
index 6d6a9eed6187d..13c7dbed004b8 100644
--- a/packages/SystemUI/res/layout/recents_history_date.xml
+++ b/packages/SystemUI/res/layout/recents_history_date.xml
@@ -15,10 +15,12 @@
 -->
 <TextView
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:theme="@android:style/Theme.Material"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:padding="12dp"
+    android:paddingStart="4dp"
+    android:paddingEnd="4dp"
+    android:paddingTop="12dp"
+    android:paddingBottom="12dp"
     android:gravity="start"
     android:textSize="14sp"
     android:textColor="#009688"
diff --git a/packages/SystemUI/res/layout/recents_history_task.xml b/packages/SystemUI/res/layout/recents_history_task.xml
index ae1100604840d..e92c24a74bf9c 100644
--- a/packages/SystemUI/res/layout/recents_history_task.xml
+++ b/packages/SystemUI/res/layout/recents_history_task.xml
@@ -15,7 +15,6 @@
 -->
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:theme="@android:style/Theme.Material"
     android:layout_width="match_parent"
     android:layout_height="48dp"
     android:orientation="horizontal"
@@ -27,7 +26,8 @@
         android:layout_width="32dp"
         android:layout_height="32dp"
         android:layout_gravity="center"
-        android:layout_marginStart="16dp" />
+        android:layout_marginStart="4dp"
+        android:layout_marginEnd="12dp" />
     <TextView
         android:id="@+id/description"
         android:layout_width="0dp"
diff --git a/packages/SystemUI/res/values/strings.xml b/packages/SystemUI/res/values/strings.xml
index a490635c35470..b09693444bdf5 100644
--- a/packages/SystemUI/res/values/strings.xml
+++ b/packages/SystemUI/res/values/strings.xml
@@ -715,9 +715,7 @@
     <!-- Recents: Launch error string. [CHAR LIMIT=NONE] -->
     <string name="recents_launch_error_message">Could not start <xliff:g id="app" example="Calendar">%s</xliff:g>.</string>
     <!-- Recents: Show history string. [CHAR LIMIT=NONE] -->
-    <string name="recents_show_history_button_label">More</string>
-    <!-- Recents: A format string to set the number of availabe historical tasks in recents. [CHAR LIMIT=NONE] -->
-    <string name="recents_history_label_format"><xliff:g id="number">%d</xliff:g> More</string>
+    <string name="recents_history_button_label">History</string>
 
     <!-- Recents: MultiStack add stack split horizontal radio button. [CHAR LIMIT=NONE] -->
     <string name="recents_multistack_add_stack_dialog_split_horizontal">Split Horizontal</string>
diff --git a/packages/SystemUI/res/values/styles.xml b/packages/SystemUI/res/values/styles.xml
index 4329f7830c4d3..e40a0f4e3932c 100644
--- a/packages/SystemUI/res/values/styles.xml
+++ b/packages/SystemUI/res/values/styles.xml
@@ -20,7 +20,7 @@
         <item name="android:windowAnimationStyle">@style/Animation.RecentsActivity</item>
     </style>
 
-    <style name="RecentsTheme" parent="@android:style/Theme.Material.Light">
+    <style name="RecentsTheme" parent="@android:style/Theme.Material">
         <!-- NoTitle -->
         <item name="android:windowNoTitle">true</item>
         <!-- Misc -->
diff --git a/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java b/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
index fa30eed792106..cd2c942f334e6 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java
@@ -57,6 +57,7 @@ import com.android.systemui.recents.events.activity.LaunchTaskFailedEvent;
 import com.android.systemui.recents.events.activity.LaunchTaskSucceededEvent;
 import com.android.systemui.recents.events.activity.ShowHistoryEvent;
 import com.android.systemui.recents.events.activity.TaskStackUpdatedEvent;
+import com.android.systemui.recents.events.activity.ToggleHistoryEvent;
 import com.android.systemui.recents.events.activity.ToggleRecentsEvent;
 import com.android.systemui.recents.events.component.RecentsVisibilityChangedEvent;
 import com.android.systemui.recents.events.component.ScreenPinningRequestEvent;
@@ -105,8 +106,6 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
     // Top level views
     private RecentsView mRecentsView;
     private SystemBarScrimViews mScrimViews;
-    private ViewStub mHistoryViewStub;
-    private RecentsHistoryView mHistoryView;
 
     // Search AppWidget
     private AppWidgetProviderInfo mSearchWidgetInfo;
@@ -127,12 +126,14 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
      * just finishing the activity since we don't know what is behind Recents in the task stack.
      */
     class FinishRecentsRunnable implements Runnable {
+
         Intent mLaunchIntent;
+        ActivityOptions mOpts;
 
         /**
          * Creates a finish runnable that starts the specified intent.
          */
-        public FinishRecentsRunnable(Intent launchIntent) {
+        public FinishRecentsRunnable(Intent launchIntent, ActivityOptions opts) {
             mLaunchIntent = launchIntent;
         }
 
@@ -141,13 +142,16 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
             try {
                 RecentsActivityLaunchState launchState =
                         Recents.getConfiguration().getLaunchState();
-                ActivityOptions opts = ActivityOptions.makeCustomAnimation(RecentsActivity.this,
-                        launchState.launchedFromSearchHome ?
-                                R.anim.recents_to_search_launcher_enter :
-                                R.anim.recents_to_launcher_enter,
-                        launchState.launchedFromSearchHome ?
-                                R.anim.recents_to_search_launcher_exit :
-                                R.anim.recents_to_launcher_exit);
+                ActivityOptions opts = mOpts;
+                if (opts == null) {
+                    opts = ActivityOptions.makeCustomAnimation(RecentsActivity.this,
+                            launchState.launchedFromSearchHome ?
+                                    R.anim.recents_to_search_launcher_enter :
+                                    R.anim.recents_to_launcher_enter,
+                            launchState.launchedFromSearchHome ?
+                                    R.anim.recents_to_search_launcher_exit :
+                                    R.anim.recents_to_launcher_exit);
+                }
                 startActivityAsUser(mLaunchIntent, opts.toBundle(), UserHandle.CURRENT);
             } catch (Exception e) {
                 Log.e(TAG, getString(R.string.recents_launch_error_message, "Home"), e);
@@ -205,12 +209,9 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
         int launchTaskIndexInStack = launchTarget != null
                 ? stack.indexOfStackTask(launchTarget)
                 : 0;
-        boolean hasStatusBarScrim = taskCount > 0;
-        boolean animateStatusBarScrim = launchState.launchedFromHome;
         boolean hasNavBarScrim = (taskCount > 0) && !config.hasTransposedNavBar;
         boolean animateNavBarScrim = true;
-        mScrimViews.prepareEnterRecentsAnimation(hasStatusBarScrim, animateStatusBarScrim,
-                hasNavBarScrim, animateNavBarScrim);
+        mScrimViews.prepareEnterRecentsAnimation(hasNavBarScrim, animateNavBarScrim);
 
         // Keep track of whether we launched from the nav bar button or via alt-tab
         if (launchState.launchedWithAltTab) {
@@ -234,8 +235,7 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
      * Dismisses the history view back into the stack view.
      */
     boolean dismissHistory() {
-        // Try and hide the history view first
-        if (mHistoryView != null && mHistoryView.isVisible()) {
+        if (mRecentsView.isHistoryVisible()) {
             EventBus.getDefault().send(new HideHistoryEvent(true /* animate */));
             return true;
         }
@@ -287,9 +287,24 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
      * Dismisses Recents directly to Home without checking whether it is currently visible.
      */
     void dismissRecentsToHome(boolean animateTaskViews) {
+        dismissRecentsToHome(animateTaskViews, null);
+    }
+
+    /**
+     * Dismisses Recents directly to Home without checking whether it is currently visible.
+     *
+     * @param overrideAnimation If not null, will override the default animation that is based on
+     *                          how Recents was launched.
+     */
+    void dismissRecentsToHome(boolean animateTaskViews, ActivityOptions overrideAnimation) {
         DismissRecentsToHomeAnimationStarted dismissEvent =
                 new DismissRecentsToHomeAnimationStarted(animateTaskViews);
-        dismissEvent.addPostAnimationCallback(mFinishLaunchHomeRunnable);
+        if (overrideAnimation != null) {
+            dismissEvent.addPostAnimationCallback(new FinishRecentsRunnable(
+                    mFinishLaunchHomeRunnable.mLaunchIntent, overrideAnimation));
+        } else {
+            dismissEvent.addPostAnimationCallback(mFinishLaunchHomeRunnable);
+        }
         dismissEvent.addPostAnimationCallback(new Runnable() {
             @Override
             public void run() {
@@ -342,7 +357,6 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
         mRecentsView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_STABLE |
                 View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN |
                 View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION);
-        mHistoryViewStub = (ViewStub) findViewById(R.id.history_view_stub);
         mScrimViews = new SystemBarScrimViews(this);
         getWindow().getAttributes().privateFlags |=
                 WindowManager.LayoutParams.PRIVATE_FLAG_FORCE_DECOR_VIEW_VISIBILITY;
@@ -360,7 +374,7 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
         homeIntent.addCategory(Intent.CATEGORY_HOME);
         homeIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
                 Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED);
-        mFinishLaunchHomeRunnable = new FinishRecentsRunnable(homeIntent);
+        mFinishLaunchHomeRunnable = new FinishRecentsRunnable(homeIntent, null);
 
         // Bind the search app widget when we first start up
         if (RecentsDebugFlags.Static.EnableSearchBar) {
@@ -441,7 +455,7 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
 
         // Reset some states
         mIgnoreAltTabRelease = false;
-        if (mHistoryView != null) {
+        if (mRecentsView.isHistoryVisible()) {
             EventBus.getDefault().send(new HideHistoryEvent(false /* animate */));
         }
 
@@ -503,8 +517,7 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
     @Override
     protected void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
-        outState.putBoolean(KEY_SAVED_STATE_HISTORY_VISIBLE,
-                (mHistoryView != null) && mHistoryView.isVisible());
+        outState.putBoolean(KEY_SAVED_STATE_HISTORY_VISIBLE, mRecentsView.isHistoryVisible());
     }
 
     @Override
@@ -651,15 +664,12 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
             }
         } else if (event.triggeredFromHomeKey) {
             // Otherwise, dismiss Recents to Home
-            if (mHistoryView != null && mHistoryView.isVisible()) {
-                HideHistoryEvent hideEvent = new HideHistoryEvent(true /* animate */);
-                hideEvent.addPostAnimationCallback(new Runnable() {
-                    @Override
-                    public void run() {
-                        dismissRecentsToHome(true /* animateTaskViews */);
-                    }
-                });
-                EventBus.getDefault().send(hideEvent);
+            if (mRecentsView.isHistoryVisible()) {
+                // If the history view is visible, then just cross-fade home
+                ActivityOptions opts = ActivityOptions.makeCustomAnimation(RecentsActivity.this,
+                                R.anim.recents_to_launcher_enter,
+                                R.anim.recents_to_launcher_exit);
+                dismissRecentsToHome(false /* animate */, opts);
 
             } else {
                 dismissRecentsToHome(true /* animateTaskViews */);
@@ -795,21 +805,6 @@ public class RecentsActivity extends Activity implements ViewTreeObserver.OnPreD
         mIgnoreAltTabRelease = true;
     }
 
-    public final void onBusEvent(ShowHistoryEvent event) {
-        if (mHistoryView == null) {
-            mHistoryView = (RecentsHistoryView) mHistoryViewStub.inflate();
-            // Since this history view is inflated by a view stub after the insets have already
-            // been applied, we have to set them ourselves initial from the insets that were last
-            // provided.
-            mHistoryView.setSystemInsets(mRecentsView.getSystemInsets());
-        }
-        mHistoryView.show(mRecentsView.getTaskStack(), event.getAnimationTrigger());
-    }
-
-    public final void onBusEvent(HideHistoryEvent event) {
-        mHistoryView.hide(event.animate, event.getAnimationTrigger());
-    }
-
     private void refreshSearchWidgetView() {
         if (mSearchWidgetInfo != null) {
             SystemServicesProxy ssp = Recents.getSystemServices();
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/activity/HideHistoryEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/activity/HideHistoryEvent.java
index af3eeb0c837dd..bacf3bdbf9764 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/events/activity/HideHistoryEvent.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/activity/HideHistoryEvent.java
@@ -21,7 +21,7 @@ import com.android.systemui.recents.events.EventBus;
 /**
  * This is sent when the history view will be closed.
  */
-public class HideHistoryEvent extends EventBus.AnimatedEvent {
+public class HideHistoryEvent extends EventBus.Event {
 
     public final boolean animate;
 
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryButtonEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryButtonEvent.java
index 7042537ea7a68..ae803ea7d1048 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryButtonEvent.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryButtonEvent.java
@@ -22,5 +22,11 @@ import com.android.systemui.recents.events.EventBus;
  * This is sent when the history view button should be shown.
  */
 public class ShowHistoryButtonEvent extends EventBus.Event {
-    // Simple event
+
+    // Whether or not to translate the history button when showing it
+    public final boolean translate;
+
+    public ShowHistoryButtonEvent(boolean translate) {
+        this.translate = translate;
+    }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryEvent.java
index b39d645b9326a..469f336ebff1c 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryEvent.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/activity/ShowHistoryEvent.java
@@ -21,7 +21,7 @@ import com.android.systemui.recents.events.EventBus;
 /**
  * This is sent when the history view button is clicked.
  */
-public class ShowHistoryEvent extends EventBus.AnimatedEvent {
+public class ShowHistoryEvent extends EventBus.Event {
 
     // Simple event
 
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/activity/ToggleHistoryEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/activity/ToggleHistoryEvent.java
new file mode 100644
index 0000000000000..aaf77afb20f95
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/activity/ToggleHistoryEvent.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2016 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.activity;
+
+import com.android.systemui.recents.events.EventBus;
+
+/**
+ * This is sent when the history view button is clicked.
+ */
+public class ToggleHistoryEvent extends EventBus.AnimatedEvent {
+
+    // Simple event
+
+}
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/ui/ResetBackgroundScrimEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/ui/ResetBackgroundScrimEvent.java
new file mode 100644
index 0000000000000..863f40b39537b
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/ui/ResetBackgroundScrimEvent.java
@@ -0,0 +1,26 @@
+/*
+ * Copyright (C) 2016 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;
+
+/**
+ * This is sent to reset the background scrim back to the initial state.
+ */
+public class ResetBackgroundScrimEvent extends EventBus.Event {
+    // Simple event
+}
diff --git a/packages/SystemUI/src/com/android/systemui/recents/events/ui/UpdateBackgroundScrimEvent.java b/packages/SystemUI/src/com/android/systemui/recents/events/ui/UpdateBackgroundScrimEvent.java
new file mode 100644
index 0000000000000..fdd4c673540db
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/recents/events/ui/UpdateBackgroundScrimEvent.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2016 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;
+
+/**
+ * This is sent to request an update to the background scrim.
+ */
+public class UpdateBackgroundScrimEvent extends EventBus.Event {
+
+    public final float alpha;
+
+    public UpdateBackgroundScrimEvent(float alpha) {
+        this.alpha = alpha;
+    }
+}
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 40009917f3919..2c28c29b925ee 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryAdapter.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryAdapter.java
@@ -166,14 +166,16 @@ public class RecentsHistoryAdapter extends RecyclerView.Adapter<RecentsHistoryAd
         final List<Task> tasksMostRecent = new ArrayList<>(stack.getHistoricalTasks());
         Collections.reverse(tasksMostRecent);
         int prevDateKey = -1;
+        int taskCount = tasksMostRecent.size();
         mRows.clear();
         mTaskRowCount.clear();
-        for (Task task : tasksMostRecent) {
+        Calendar cal = Calendar.getInstance(l);
+        for (int i = 0; i < taskCount; i++) {
+            Task task = tasksMostRecent.get(i);
             if (task.isFreeformTask()) {
                 continue;
             }
 
-            Calendar cal = Calendar.getInstance(l);
             cal.setTimeInMillis(task.key.lastActiveTime);
             int dateKey = Objects.hash(cal.get(Calendar.YEAR), cal.get(Calendar.DAY_OF_YEAR));
             if (dateKey != prevDateKey) {
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 b9921b6940abc..6dd4b53a6ddc4 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/history/RecentsHistoryView.java
@@ -16,6 +16,7 @@
 
 package com.android.systemui.recents.history;
 
+import android.animation.ValueAnimator;
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Rect;
@@ -37,22 +38,29 @@ import com.android.systemui.recents.RecentsActivity;
 import com.android.systemui.recents.RecentsConfiguration;
 import com.android.systemui.recents.events.EventBus;
 import com.android.systemui.recents.events.activity.PackagesChangedEvent;
+import com.android.systemui.recents.events.ui.ResetBackgroundScrimEvent;
+import com.android.systemui.recents.events.ui.UpdateBackgroundScrimEvent;
 import com.android.systemui.recents.misc.ReferenceCountedTrigger;
 import com.android.systemui.recents.model.TaskStack;
+import com.android.systemui.recents.views.AnimateableViewBounds;
+import com.android.systemui.statusbar.phone.PhoneStatusBar;
 
 /**
  * A list of the recent tasks that are not in the stack.
  */
-public class RecentsHistoryView extends LinearLayout {
+public class RecentsHistoryView extends LinearLayout
+        implements ValueAnimator.AnimatorUpdateListener {
 
-    private static final String TAG = "RecentsHistoryView";
-    private static final boolean DEBUG = false;
+    private static final float TRANSLATION_Y_PCT = 0.25f;
+    private static final float BG_SCRIM_ALPHA = 0.625f;
 
     private RecyclerView mRecyclerView;
     private RecentsHistoryAdapter mAdapter;
     private RecentsHistoryItemTouchCallbacks mItemTouchHandler;
+    private AnimateableViewBounds mViewBounds;
     private boolean mIsVisible;
     private Rect mSystemInsets = new Rect();
+    private int mHeaderHeight;
 
     private Interpolator mFastOutSlowInInterpolator;
     private Interpolator mFastOutLinearInInterpolator;
@@ -81,27 +89,28 @@ public class RecentsHistoryView extends LinearLayout {
                 com.android.internal.R.interpolator.fast_out_slow_in);
         mFastOutLinearInInterpolator = AnimationUtils.loadInterpolator(context,
                 com.android.internal.R.interpolator.fast_out_linear_in);
+        mViewBounds = new AnimateableViewBounds(this, 0);
+        setOutlineProvider(mViewBounds);
     }
 
     /**
      * Updates this history view with the recent tasks, and then shows it.
      */
-    public void show(TaskStack stack, ReferenceCountedTrigger postHideAnimationTrigger) {
+    public void show(TaskStack stack, int stackHeight) {
         setVisibility(View.VISIBLE);
         setAlpha(0f);
-        postHideAnimationTrigger.addLastDecrementRunnable(new Runnable() {
-            @Override
-            public void run() {
-                animate()
-                        .alpha(1f)
-                        .setDuration(mHistoryTransitionDuration)
-                        .setInterpolator(mFastOutSlowInInterpolator)
-                        .withLayer()
-                        .start();
-            }
-        });
+        setTranslationY(-stackHeight * TRANSLATION_Y_PCT);
+        animate()
+                .alpha(1f)
+                .translationY(0f)
+                .setDuration(mHistoryTransitionDuration)
+                .setInterpolator(mFastOutSlowInInterpolator)
+                .setUpdateListener(this)
+                .withLayer()
+                .start();
         mAdapter.updateTasks(getContext(), stack);
         mIsVisible = true;
+        EventBus.getDefault().send(new UpdateBackgroundScrimEvent(BG_SCRIM_ALPHA));
 
         MetricsLogger.visible(mRecyclerView.getContext(), MetricsEvent.OVERVIEW_HISTORY);
     }
@@ -109,31 +118,28 @@ public class RecentsHistoryView extends LinearLayout {
     /**
      * Hides this history view.
      */
-    public void hide(boolean animate, final ReferenceCountedTrigger postAnimationTrigger) {
+    public void hide(boolean animate, int stackHeight) {
         if (animate) {
             animate()
                     .alpha(0f)
+                    .translationY(-stackHeight * TRANSLATION_Y_PCT)
                     .setDuration(mHistoryTransitionDuration)
                     .setInterpolator(mFastOutLinearInInterpolator)
+                    .setUpdateListener(this)
                     .withEndAction(new Runnable() {
                         @Override
                         public void run() {
                             setVisibility(View.INVISIBLE);
-                            if (postAnimationTrigger != null) {
-                                postAnimationTrigger.decrement();
-                            }
                         }
                     })
                     .withLayer()
                     .start();
-            if (postAnimationTrigger != null) {
-                postAnimationTrigger.increment();
-            }
         } else {
             setAlpha(0f);
             setVisibility(View.INVISIBLE);
         }
         mIsVisible = false;
+        EventBus.getDefault().send(new ResetBackgroundScrimEvent());
 
         MetricsLogger.hidden(mRecyclerView.getContext(), MetricsEvent.OVERVIEW_HISTORY);
     }
@@ -142,7 +148,15 @@ public class RecentsHistoryView extends LinearLayout {
      * Updates the system insets of this history view to the provided values.
      */
     public void setSystemInsets(Rect systemInsets) {
-        mSystemInsets.set(systemInsets.left, systemInsets.top, systemInsets.right, systemInsets.bottom);
+        mSystemInsets.set(systemInsets);
+        requestLayout();
+    }
+
+    /**
+     * Updates the header height to account for the history button bar.
+     */
+    public void setHeaderHeight(int height) {
+        mHeaderHeight = height;
         requestLayout();
     }
 
@@ -177,7 +191,7 @@ public class RecentsHistoryView extends LinearLayout {
         int stackHeightPadding = mContext.getResources().getDimensionPixelSize(
                 R.dimen.recents_stack_top_padding);
         mRecyclerView.setPadding(stackWidthPadding + mSystemInsets.left,
-                stackHeightPadding + mSystemInsets.top,
+                stackHeightPadding + mSystemInsets.top + mHeaderHeight,
                 stackWidthPadding + mSystemInsets.right, mSystemInsets.bottom);
 
         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
@@ -201,6 +215,13 @@ public class RecentsHistoryView extends LinearLayout {
         return insets;
     }
 
+    @Override
+    public void onAnimationUpdate(ValueAnimator animation) {
+        // Clip the top of the view by the header bar height
+        int top = Math.max(0, (int) -getTranslationY()) + mSystemInsets.top + mHeaderHeight;
+        mViewBounds.setClipTop(top);
+    }
+
     /**** EventBus Events ****/
 
     public final void onBusEvent(PackagesChangedEvent event) {
diff --git a/packages/SystemUI/src/com/android/systemui/recents/model/RecentsTaskLoadPlan.java b/packages/SystemUI/src/com/android/systemui/recents/model/RecentsTaskLoadPlan.java
index d15828a965548..3029acfac2fe7 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/model/RecentsTaskLoadPlan.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/model/RecentsTaskLoadPlan.java
@@ -37,6 +37,7 @@ import com.android.systemui.recents.misc.SystemServicesProxy;
 
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Formatter;
 import java.util.List;
 
 
@@ -130,6 +131,7 @@ public class RecentsTaskLoadPlan {
         SparseIntArray affiliatedTaskCounts = new SparseIntArray();
         String dismissDescFormat = mContext.getString(
                 R.string.accessibility_recents_item_will_be_dismissed);
+        Formatter dismissDescFormatter = new Formatter();
         long lastStackActiveTime = Prefs.getLong(mContext,
                 Prefs.Key.OVERVIEW_LAST_STACK_TASK_ACTIVE_TIME, 0);
         if (RecentsDebugFlags.Static.EnableMockTasks) {
@@ -168,7 +170,8 @@ public class RecentsTaskLoadPlan {
             // Load the title, icon, and color
             String title = loader.getAndUpdateActivityTitle(taskKey, t.taskDescription);
             String contentDescription = loader.getAndUpdateContentDescription(taskKey, res);
-            String dismissDescription = String.format(dismissDescFormat, contentDescription);
+            String dismissDescription = dismissDescFormatter.format(dismissDescFormat,
+                    contentDescription).toString();
             Drawable icon = isStackTask
                     ? loader.getAndUpdateActivityIcon(taskKey, t.taskDescription, res, false)
                     : null;
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/AnimateableViewBounds.java b/packages/SystemUI/src/com/android/systemui/recents/views/AnimateableViewBounds.java
index 5a72897d6847d..584209510e450 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/AnimateableViewBounds.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/AnimateableViewBounds.java
@@ -48,10 +48,16 @@ public class AnimateableViewBounds extends ViewOutlineProvider {
     @Override
     public void getOutline(View view, Outline outline) {
         outline.setAlpha(mMinAlpha + mAlpha / (1f - mMinAlpha));
-        outline.setRoundRect(mClipRect.left, mClipRect.top,
-                mSourceView.getWidth() - mClipRect.right,
-                mSourceView.getHeight() - mClipRect.bottom,
-                mCornerRadius);
+        if (mCornerRadius > 0) {
+            outline.setRoundRect(mClipRect.left, mClipRect.top,
+                    mSourceView.getWidth() - mClipRect.right,
+                    mSourceView.getHeight() - mClipRect.bottom,
+                    mCornerRadius);
+        } else {
+            outline.setRect(mClipRect.left, mClipRect.top,
+                    mSourceView.getWidth() - mClipRect.right,
+                    mSourceView.getHeight() - mClipRect.bottom);
+        }
     }
 
     /** Sets the view outline alpha. */
@@ -63,6 +69,17 @@ public class AnimateableViewBounds extends ViewOutlineProvider {
         }
     }
 
+    /** Sets the top clip. */
+    public void setClipTop(int top) {
+        mClipRect.top = top;
+        updateClipBounds();
+    }
+
+    /** Returns the top clip. */
+    public int getClipTop() {
+        return mClipRect.top;
+    }
+
     /** Sets the bottom clip. */
     public void setClipBottom(int bottom) {
         mClipRect.bottom = bottom;
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
index a00b4978679c8..41739c4acd7ec 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java
@@ -18,9 +18,13 @@ package com.android.systemui.recents.views;
 
 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
+import android.animation.ObjectAnimator;
 import android.content.Context;
 import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Outline;
 import android.graphics.Rect;
+import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
 import android.os.Handler;
 import android.util.ArraySet;
@@ -28,7 +32,9 @@ import android.util.AttributeSet;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
 import android.view.View;
+import android.view.ViewOutlineProvider;
 import android.view.ViewPropertyAnimator;
+import android.view.ViewStub;
 import android.view.WindowInsets;
 import android.view.animation.AnimationUtils;
 import android.view.animation.Interpolator;
@@ -45,20 +51,24 @@ import com.android.systemui.recents.RecentsAppWidgetHostView;
 import com.android.systemui.recents.RecentsConfiguration;
 import com.android.systemui.recents.RecentsDebugFlags;
 import com.android.systemui.recents.events.EventBus;
-import com.android.systemui.recents.events.activity.CancelEnterRecentsWindowAnimationEvent;
 import com.android.systemui.recents.events.activity.DismissRecentsToHomeAnimationStarted;
+import com.android.systemui.recents.events.activity.EnterRecentsWindowAnimationCompletedEvent;
 import com.android.systemui.recents.events.activity.HideHistoryButtonEvent;
 import com.android.systemui.recents.events.activity.HideHistoryEvent;
 import com.android.systemui.recents.events.activity.LaunchTaskEvent;
 import com.android.systemui.recents.events.activity.ShowHistoryButtonEvent;
 import com.android.systemui.recents.events.activity.ShowHistoryEvent;
 import com.android.systemui.recents.events.activity.TaskStackUpdatedEvent;
+import com.android.systemui.recents.events.activity.ToggleHistoryEvent;
 import com.android.systemui.recents.events.component.RecentsVisibilityChangedEvent;
 import com.android.systemui.recents.events.ui.DraggingInRecentsEndedEvent;
 import com.android.systemui.recents.events.ui.DraggingInRecentsEvent;
+import com.android.systemui.recents.events.ui.ResetBackgroundScrimEvent;
+import com.android.systemui.recents.events.ui.UpdateBackgroundScrimEvent;
 import com.android.systemui.recents.events.ui.dragndrop.DragDropTargetChangedEvent;
 import com.android.systemui.recents.events.ui.dragndrop.DragEndEvent;
 import com.android.systemui.recents.events.ui.dragndrop.DragStartEvent;
+import com.android.systemui.recents.history.RecentsHistoryView;
 import com.android.systemui.recents.misc.ReferenceCountedTrigger;
 import com.android.systemui.recents.misc.SystemServicesProxy;
 import com.android.systemui.recents.misc.Utilities;
@@ -80,6 +90,8 @@ import static android.app.ActivityManager.StackId.INVALID_STACK_ID;
 public class RecentsView extends FrameLayout {
 
     private static final int DOCK_AREA_OVERLAY_TRANSITION_DURATION = 135;
+    private static final int DEFAULT_UPDATE_SCRIM_DURATION = 200;
+    private static final float DEFAULT_SCRIM_ALPHA = 0.33f;
 
     private final Handler mHandler;
 
@@ -88,11 +100,16 @@ public class RecentsView extends FrameLayout {
     private RecentsAppWidgetHostView mSearchBar;
     private TextView mHistoryButton;
     private View mEmptyView;
+    private RecentsHistoryView mHistoryView;
+
     private boolean mAwaitingFirstLayout = true;
     private boolean mLastTaskLaunchedWasFreeform;
     private Rect mSystemInsets = new Rect();
     private int mDividerSize;
 
+    private ColorDrawable mBackgroundScrim = new ColorDrawable(Color.BLACK);
+    private Animator mBackgroundScrimAnimator;
+
     private RecentsTransitionHelper mTransitionHelper;
     private RecentsViewTouchHandler mTouchHandler;
 
@@ -127,17 +144,28 @@ public class RecentsView extends FrameLayout {
         mTouchHandler = new RecentsViewTouchHandler(this);
         mFlingAnimationUtils = new FlingAnimationUtils(context, 0.3f);
 
+        final float cornerRadius = context.getResources().getDimensionPixelSize(
+                R.dimen.recents_task_view_rounded_corners_radius);
         LayoutInflater inflater = LayoutInflater.from(context);
         mHistoryButton = (TextView) inflater.inflate(R.layout.recents_history_button, this, false);
         mHistoryButton.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
-                EventBus.getDefault().send(new ShowHistoryEvent());
+                EventBus.getDefault().send(new ToggleHistoryEvent());
+            }
+        });
+        mHistoryButton.setClipToOutline(true);
+        mHistoryButton.setOutlineProvider(new ViewOutlineProvider() {
+            @Override
+            public void getOutline(View view, Outline outline) {
+                outline.setRoundRect(0, 0, view.getWidth(), view.getHeight(), cornerRadius);
             }
         });
         addView(mHistoryButton);
         mEmptyView = inflater.inflate(R.layout.recents_empty, this, false);
         addView(mEmptyView);
+
+        setBackground(mBackgroundScrim);
     }
 
     /** Set/get the bsp root node */
@@ -162,6 +190,15 @@ public class RecentsView extends FrameLayout {
             addView(mTaskStackView);
         }
 
+        // If we are already occluded by the app, then just set the default background scrim now.
+        // Otherwise, defer until the enter animation completes to animate the scrim with the
+        // tasks for the home animation.
+        if (launchState.launchedFromAppWithThumbnail || mStack.getTaskCount() == 0) {
+            mBackgroundScrim.setAlpha((int) (DEFAULT_SCRIM_ALPHA * 255));
+        } else {
+            mBackgroundScrim.setAlpha(0);
+        }
+
         // Update the top level view's visibilities
         if (stack.getTaskCount() > 0) {
             hideEmptyView();
@@ -180,6 +217,13 @@ public class RecentsView extends FrameLayout {
         return mLastTaskLaunchedWasFreeform;
     }
 
+    /**
+     * Returns whether the history is visible or not.
+     */
+    public boolean isHistoryVisible() {
+        return mHistoryView != null && mHistoryView.isVisible();
+    }
+
     /**
      * Returns the currently set task stack.
      */
@@ -304,13 +348,6 @@ public class RecentsView extends FrameLayout {
         mHistoryButton.bringToFront();
     }
 
-    /**
-     * Returns the last known system insets.
-     */
-    public Rect getSystemInsets() {
-        return mSystemInsets;
-    }
-
     @Override
     protected void onAttachedToWindow() {
         EventBus.getDefault().register(this, RecentsActivity.EVENT_BUS_PRIORITY + 1);
@@ -352,17 +389,23 @@ public class RecentsView extends FrameLayout {
             mTaskStackView.measure(widthMeasureSpec, heightMeasureSpec);
         }
 
-        // Measure the empty view
-        measureChild(mEmptyView, MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
-                MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
+        // Measure the empty view to the full size of the screen
+        if (mEmptyView.getVisibility() != GONE) {
+            measureChild(mEmptyView, MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
+                    MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
+        }
 
-        // Measure the history button with the full space above the stack, but width-constrained
-        // to the stack
+        // Measure the history view
+        if (mHistoryView != null && mHistoryView.getVisibility() != GONE) {
+            measureChild(mHistoryView, MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
+                    MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
+        }
+
+        // Measure the history button within the constraints of the space above the stack
         Rect historyButtonRect = mTaskStackView.mLayoutAlgorithm.mHistoryButtonRect;
         measureChild(mHistoryButton,
-                MeasureSpec.makeMeasureSpec(historyButtonRect.width(), MeasureSpec.EXACTLY),
-                MeasureSpec.makeMeasureSpec(historyButtonRect.height(),
-                        MeasureSpec.EXACTLY));
+                MeasureSpec.makeMeasureSpec(historyButtonRect.width(), MeasureSpec.AT_MOST),
+                MeasureSpec.makeMeasureSpec(historyButtonRect.height(), MeasureSpec.AT_MOST));
 
         setMeasuredDimension(width, height);
     }
@@ -389,13 +432,24 @@ public class RecentsView extends FrameLayout {
         }
 
         // Layout the empty view
-        mEmptyView.layout(left, top, right, bottom);
+        if (mEmptyView.getVisibility() != GONE) {
+            mEmptyView.layout(left, top, right, bottom);
+        }
 
-        // Layout the history button left-aligned with the stack, but offset from the top of the
-        // view
+        // Layout the history view
+        if (mHistoryView != null && mHistoryView.getVisibility() != GONE) {
+            mHistoryView.layout(left, top, right, bottom);
+        }
+
+        // Layout the history button such that its drawable is left-aligned with the stack,
+        // vertically centered in the available space above the stack
         Rect historyButtonRect = mTaskStackView.mLayoutAlgorithm.mHistoryButtonRect;
-        mHistoryButton.layout(historyButtonRect.left, historyButtonRect.top,
-                historyButtonRect.right, historyButtonRect.bottom);
+        int historyLeft = historyButtonRect.left - mHistoryButton.getPaddingStart();
+        int historyTop = historyButtonRect.top +
+                (historyButtonRect.height() - mHistoryButton.getMeasuredHeight()) / 2;
+        mHistoryButton.layout(historyLeft, historyTop,
+                historyLeft + mHistoryButton.getMeasuredWidth(),
+                historyTop + mHistoryButton.getMeasuredHeight());
 
         if (mAwaitingFirstLayout) {
             mAwaitingFirstLayout = false;
@@ -464,10 +518,8 @@ public class RecentsView extends FrameLayout {
         // Hide the history button
         int taskViewExitToHomeDuration = getResources().getInteger(
                 R.integer.recents_task_exit_to_home_duration);
-        hideHistoryButton(taskViewExitToHomeDuration);
-
-        // If we are going home, cancel the previous task's window transition
-        EventBus.getDefault().send(new CancelEnterRecentsWindowAnimationEvent(null));
+        hideHistoryButton(taskViewExitToHomeDuration, false /* translate */);
+        animateBackgroundScrim(0f, taskViewExitToHomeDuration);
     }
 
     public final void onBusEvent(DragStartEvent event) {
@@ -572,57 +624,127 @@ public class RecentsView extends FrameLayout {
         animator.start();
     }
 
-    public final void onBusEvent(ShowHistoryEvent event) {
-        // Hide the history button when the history view is shown
-        hideHistoryButton(getResources().getInteger(R.integer.recents_history_transition_duration),
-                event.getAnimationTrigger());
-        event.addPostAnimationCallback(new Runnable() {
-            @Override
-            public void run() {
-                setAlpha(0f);
-            }
-        });
-    }
-
-    public final void onBusEvent(HideHistoryEvent event) {
-        // Show the history button when the history view is hidden
-        setAlpha(1f);
-        showHistoryButton(getResources().getInteger(R.integer.recents_history_transition_duration),
-                event.getAnimationTrigger());
-    }
-
-    public final void onBusEvent(ShowHistoryButtonEvent event) {
-        showHistoryButton(150);
-    }
-
-    public final void onBusEvent(HideHistoryButtonEvent event) {
-        hideHistoryButton(100);
-    }
-
     public final void onBusEvent(TaskStackUpdatedEvent event) {
         mStack.setTasks(event.stack.computeAllTasksList(), true /* notifyStackChanges */);
         mStack.createAffiliatedGroupings(getContext());
     }
 
+    public final void onBusEvent(EnterRecentsWindowAnimationCompletedEvent event) {
+        RecentsActivityLaunchState launchState = Recents.getConfiguration().getLaunchState();
+        if (!launchState.launchedFromAppWithThumbnail && mStack.getTaskCount() > 0) {
+            int taskViewEnterFromHomeDuration = getResources().getInteger(
+                    R.integer.recents_task_enter_from_home_duration);
+            animateBackgroundScrim(DEFAULT_SCRIM_ALPHA, taskViewEnterFromHomeDuration);
+        }
+    }
+
+    public final void onBusEvent(UpdateBackgroundScrimEvent event) {
+        animateBackgroundScrim(event.alpha, DEFAULT_UPDATE_SCRIM_DURATION);
+    }
+
+    public final void onBusEvent(ResetBackgroundScrimEvent event) {
+        animateBackgroundScrim(DEFAULT_SCRIM_ALPHA, DEFAULT_UPDATE_SCRIM_DURATION);
+    }
+
+    public final void onBusEvent(RecentsVisibilityChangedEvent event) {
+        if (!event.visible) {
+            // Reset the view state
+            mAwaitingFirstLayout = true;
+            mLastTaskLaunchedWasFreeform = false;
+            hideHistoryButton(0, false /* translate */);
+        }
+    }
+
+    public final void onBusEvent(ToggleHistoryEvent event) {
+        if (mHistoryView != null && mHistoryView.isVisible()) {
+            EventBus.getDefault().send(new HideHistoryEvent(true /* animate */));
+        } else {
+            EventBus.getDefault().send(new ShowHistoryEvent());
+        }
+    }
+
+    public final void onBusEvent(ShowHistoryEvent event) {
+        if (mHistoryView == null) {
+            mHistoryView = (RecentsHistoryView) LayoutInflater.from(getContext()).inflate(
+                    R.layout.recents_history, this, false);
+            addView(mHistoryView);
+
+            // Since this history view is inflated by a view stub after the insets have already
+            // been applied, we have to set them ourselves initial from the insets that were last
+            // provided.
+            mHistoryView.setSystemInsets(mSystemInsets);
+            mHistoryView.setHeaderHeight(mHistoryButton.getMeasuredHeight());
+            mHistoryButton.bringToFront();
+        }
+
+        // Animate the empty view in parallel with the history view (the task view animations are
+        // handled in TaskStackView)
+        Rect stackRect = mTaskStackView.mLayoutAlgorithm.mStackRect;
+        if (mEmptyView.getVisibility() == View.VISIBLE) {
+            int historyTransitionDuration = getResources().getInteger(
+                    R.integer.recents_history_transition_duration);
+            mEmptyView.animate()
+                    .alpha(0f)
+                    .translationY(stackRect.bottom)
+                    .setDuration(historyTransitionDuration)
+                    .setInterpolator(mFastOutSlowInInterpolator)
+                    .withEndAction(new Runnable() {
+                        @Override
+                        public void run() {
+                            mEmptyView.setVisibility(View.INVISIBLE);
+                        }
+                    })
+                    .start();
+        }
+
+        mHistoryView.show(mStack, stackRect.height());
+    }
+
+    public final void onBusEvent(HideHistoryEvent event) {
+        // Animate the empty view in parallel with the history view (the task view animations are
+        // handled in TaskStackView)
+        Rect stackRect = mTaskStackView.mLayoutAlgorithm.mStackRect;
+        if (mStack.getTaskCount() == 0) {
+            int historyTransitionDuration = getResources().getInteger(
+                    R.integer.recents_history_transition_duration);
+            mEmptyView.setVisibility(View.VISIBLE);
+            mEmptyView.animate()
+                    .alpha(1f)
+                    .translationY(0)
+                    .setDuration(historyTransitionDuration)
+                    .setInterpolator(mFastOutSlowInInterpolator)
+                    .start();
+        }
+
+        mHistoryView.hide(event.animate, stackRect.height());
+    }
+
+    public final void onBusEvent(ShowHistoryButtonEvent event) {
+        showHistoryButton(150, event.translate);
+    }
+
+    public final void onBusEvent(HideHistoryButtonEvent event) {
+        hideHistoryButton(100, true /* translate */);
+    }
+
     /**
      * Shows the history button.
      */
-    private void showHistoryButton(final int duration) {
-        ReferenceCountedTrigger postAnimationTrigger = new ReferenceCountedTrigger();
-        showHistoryButton(duration, postAnimationTrigger);
-        postAnimationTrigger.flushLastDecrementRunnables();
-    }
-
-    private void showHistoryButton(final int duration,
-            final ReferenceCountedTrigger postHideHistoryAnimationTrigger) {
-        mHistoryButton.setText(getContext().getString(R.string.recents_history_label_format,
-                mStack.getHistoricalTasks().size()));
+    private void showHistoryButton(final int duration, final boolean translate) {
+        final ReferenceCountedTrigger postAnimationTrigger = new ReferenceCountedTrigger();
         if (mHistoryButton.getVisibility() == View.INVISIBLE) {
             mHistoryButton.setVisibility(View.VISIBLE);
             mHistoryButton.setAlpha(0f);
-            postHideHistoryAnimationTrigger.addLastDecrementRunnable(new Runnable() {
+            if (translate) {
+                mHistoryButton.setTranslationY(-mHistoryButton.getMeasuredHeight() * 0.25f);
+            }
+            postAnimationTrigger.addLastDecrementRunnable(new Runnable() {
                 @Override
                 public void run() {
+                    if (translate) {
+                        mHistoryButton.animate()
+                            .translationY(0f);
+                    }
                     mHistoryButton.animate()
                             .alpha(1f)
                             .setDuration(duration)
@@ -632,34 +754,42 @@ public class RecentsView extends FrameLayout {
                 }
             });
         }
+        postAnimationTrigger.flushLastDecrementRunnables();
     }
 
     /**
      * Hides the history button.
      */
-    private void hideHistoryButton(int duration) {
-        ReferenceCountedTrigger postAnimationTrigger = new ReferenceCountedTrigger();
-        hideHistoryButton(duration, postAnimationTrigger);
+    private void hideHistoryButton(int duration, boolean translate) {
+        final ReferenceCountedTrigger postAnimationTrigger = new ReferenceCountedTrigger();
+        hideHistoryButton(duration, translate, postAnimationTrigger);
         postAnimationTrigger.flushLastDecrementRunnables();
     }
 
-    private void hideHistoryButton(int duration,
-            final ReferenceCountedTrigger postHideStackAnimationTrigger) {
+    /**
+     * Hides the history button.
+     */
+    private void hideHistoryButton(int duration, boolean translate,
+            final ReferenceCountedTrigger postAnimationTrigger) {
         if (mHistoryButton.getVisibility() == View.VISIBLE) {
+            if (translate) {
+                mHistoryButton.animate()
+                    .translationY(-mHistoryButton.getMeasuredHeight() * 0.25f);
+            }
             mHistoryButton.animate()
                     .alpha(0f)
                     .setDuration(duration)
-                    .setInterpolator(mFastOutLinearInInterpolator)
+                    .setInterpolator(mFastOutSlowInInterpolator)
                     .withEndAction(new Runnable() {
                         @Override
                         public void run() {
                             mHistoryButton.setVisibility(View.INVISIBLE);
-                            postHideStackAnimationTrigger.decrement();
+                            postAnimationTrigger.decrement();
                         }
                     })
                     .withLayer()
                     .start();
-            postHideStackAnimationTrigger.increment();
+            postAnimationTrigger.increment();
         }
     }
 
@@ -696,11 +826,18 @@ public class RecentsView extends FrameLayout {
         }
     }
 
-    public final void onBusEvent(RecentsVisibilityChangedEvent event) {
-        if (!event.visible) {
-            // Reset the view state
-            mAwaitingFirstLayout = true;
-            mLastTaskLaunchedWasFreeform = false;
-        }
+    /**
+     * Animates the background scrim to the given {@param alpha}.
+     */
+    private void animateBackgroundScrim(float alpha, int duration) {
+        Utilities.cancelAnimationWithoutCallbacks(mBackgroundScrimAnimator);
+        int alphaInt = (int) (alpha * 255);
+        mBackgroundScrimAnimator = ObjectAnimator.ofInt(mBackgroundScrim, Utilities.DRAWABLE_ALPHA,
+                mBackgroundScrim.getAlpha(), alphaInt);
+        mBackgroundScrimAnimator.setDuration(duration);
+        mBackgroundScrimAnimator.setInterpolator(alphaInt > mBackgroundScrim.getAlpha()
+                ? PhoneStatusBar.ALPHA_OUT
+                : PhoneStatusBar.ALPHA_IN);
+        mBackgroundScrimAnimator.start();
     }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/SystemBarScrimViews.java b/packages/SystemUI/src/com/android/systemui/recents/views/SystemBarScrimViews.java
index 9618f212d9832..2254dfc316e64 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/SystemBarScrimViews.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/SystemBarScrimViews.java
@@ -30,12 +30,9 @@ public class SystemBarScrimViews {
 
     Context mContext;
 
-    View mStatusBarScrimView;
     View mNavBarScrimView;
 
     boolean mHasNavBarScrim;
-    boolean mShouldAnimateStatusBarScrim;
-    boolean mHasStatusBarScrim;
     boolean mShouldAnimateNavBarScrim;
 
     int mNavBarScrimEnterDuration;
@@ -45,7 +42,6 @@ public class SystemBarScrimViews {
 
     public SystemBarScrimViews(Activity activity) {
         mContext = activity;
-        mStatusBarScrimView = activity.findViewById(R.id.status_bar_scrim);
         mNavBarScrimView = activity.findViewById(R.id.nav_bar_scrim);
         mNavBarScrimEnterDuration = activity.getResources().getInteger(
                 R.integer.recents_nav_bar_scrim_enter_duration);
@@ -59,17 +55,12 @@ public class SystemBarScrimViews {
      * Prepares the scrim views for animating when entering Recents. This will be called before
      * the first draw.
      */
-    public void prepareEnterRecentsAnimation(boolean hasStatusBarScrim, boolean animateStatusBarScrim,
-            boolean hasNavBarScrim, boolean animateNavBarScrim) {
-        mHasNavBarScrim = hasStatusBarScrim;
-        mShouldAnimateStatusBarScrim = animateStatusBarScrim;
-        mHasStatusBarScrim = hasNavBarScrim;
+    public void prepareEnterRecentsAnimation(boolean hasNavBarScrim, boolean animateNavBarScrim) {
+        mHasNavBarScrim = hasNavBarScrim;
         mShouldAnimateNavBarScrim = animateNavBarScrim;
 
         mNavBarScrimView.setVisibility(mHasNavBarScrim && !mShouldAnimateNavBarScrim ?
                 View.VISIBLE : View.INVISIBLE);
-        mStatusBarScrimView.setVisibility(mHasStatusBarScrim && !mShouldAnimateStatusBarScrim ?
-                View.VISIBLE : View.INVISIBLE);
     }
 
     /**** EventBus events ****/
@@ -78,20 +69,6 @@ public class SystemBarScrimViews {
      * Starts animating the scrim views when entering Recents.
      */
     public final void onBusEvent(EnterRecentsWindowAnimationCompletedEvent event) {
-        if (mHasStatusBarScrim && mShouldAnimateStatusBarScrim) {
-            mStatusBarScrimView.setTranslationY(-mStatusBarScrimView.getMeasuredHeight());
-            mStatusBarScrimView.animate()
-                    .translationY(0)
-                    .setDuration(mNavBarScrimEnterDuration)
-                    .setInterpolator(mQuintOutInterpolator)
-                    .withStartAction(new Runnable() {
-                        @Override
-                        public void run() {
-                            mStatusBarScrimView.setVisibility(View.VISIBLE);
-                        }
-                    })
-                    .start();
-        }
         if (mHasNavBarScrim && mShouldAnimateNavBarScrim) {
             mNavBarScrimView.setTranslationY(mNavBarScrimView.getMeasuredHeight());
             mNavBarScrimView.animate()
@@ -115,14 +92,6 @@ public class SystemBarScrimViews {
     public final void onBusEvent(DismissRecentsToHomeAnimationStarted event) {
         int taskViewExitToAppDuration = mContext.getResources().getInteger(
                 R.integer.recents_task_exit_to_app_duration);
-        if (mHasStatusBarScrim && mShouldAnimateStatusBarScrim) {
-            mStatusBarScrimView.animate()
-                    .translationY(-mStatusBarScrimView.getMeasuredHeight())
-                    .setStartDelay(0)
-                    .setDuration(taskViewExitToAppDuration)
-                    .setInterpolator(mFastOutSlowInInterpolator)
-                    .start();
-        }
         if (mHasNavBarScrim && mShouldAnimateNavBarScrim) {
             mNavBarScrimView.animate()
                     .translationY(mNavBarScrimView.getMeasuredHeight())
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackAnimationHelper.java b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackAnimationHelper.java
index ccbb329bb151b..d550d8352c231 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackAnimationHelper.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackAnimationHelper.java
@@ -138,7 +138,7 @@ public class TaskStackAnimationHelper {
             } else if (launchState.launchedFromHome) {
                 // Move the task view off screen (below) so we can animate it in
                 RectF bounds = new RectF(mTmpTransform.rect);
-                bounds.offset(0, offscreenY);
+                bounds.offsetTo(bounds.left, offscreenY);
                 tv.setLeftTopRightBottom((int) bounds.left, (int) bounds.top, (int) bounds.right,
                         (int) bounds.bottom);
             }
@@ -259,7 +259,7 @@ public class TaskStackAnimationHelper {
 
             stackLayout.getStackTransform(task, stackScroller.getStackScroll(), mTmpTransform,
                     null);
-            mTmpTransform.rect.offset(0, offscreenY);
+            mTmpTransform.rect.offsetTo(mTmpTransform.rect.left, offscreenY);
             mStackView.updateTaskViewToTransform(tv, mTmpTransform, taskAnimation);
         }
     }
@@ -346,61 +346,58 @@ public class TaskStackAnimationHelper {
     }
 
     /**
-     * Starts the animation to hide the {@link TaskView}s when the history is shown.  The history
-     * view's animation will be deferred until all the {@link TaskView}s are finished animating.
+     * Starts the animation to hide the {@link TaskView}s when the history is shown.
      */
     public void startShowHistoryAnimation(ReferenceCountedTrigger postAnimationTrigger) {
         Resources res = mStackView.getResources();
         TaskStackLayoutAlgorithm stackLayout = mStackView.getStackAlgorithm();
         TaskStackViewScroller stackScroller = mStackView.getScroller();
 
+        int offscreenY = stackLayout.mStackRect.bottom;
         int historyTransitionDuration = res.getInteger(
                 R.integer.recents_history_transition_duration);
+        int startDelayIncr = 16;
 
         List<TaskView> taskViews = mStackView.getTaskViews();
         int taskViewCount = taskViews.size();
         for (int i = taskViewCount - 1; i >= 0; i--) {
             TaskView tv = taskViews.get(i);
             Task task = tv.getTask();
-            TaskViewAnimation taskAnimation = new TaskViewAnimation(
-                    historyTransitionDuration, PhoneStatusBar.ALPHA_OUT,
+            TaskViewAnimation taskAnimation = new TaskViewAnimation(startDelayIncr * i,
+                    historyTransitionDuration, mFastOutSlowInInterpolator,
                     postAnimationTrigger.decrementOnAnimationEnd());
             postAnimationTrigger.increment();
 
             stackLayout.getStackTransform(task, stackScroller.getStackScroll(), mTmpTransform,
                     null);
             mTmpTransform.alpha = 0f;
+            mTmpTransform.rect.offsetTo(mTmpTransform.rect.left, offscreenY);
             mStackView.updateTaskViewToTransform(tv, mTmpTransform, taskAnimation);
         }
     }
 
     /**
-     * Starts the animation to show the {@link TaskView}s when the history is hidden.  The
-     * {@link TaskView} animations will be deferred until the history view has been animated away.
+     * Starts the animation to show the {@link TaskView}s when the history is hidden.
      */
-    public void startHideHistoryAnimation(final ReferenceCountedTrigger postAnimationTrigger) {
-        final Resources res = mStackView.getResources();
-        final TaskStackLayoutAlgorithm stackLayout = mStackView.getStackAlgorithm();
-        final TaskStackViewScroller stackScroller = mStackView.getScroller();
+    public void startHideHistoryAnimation() {
+        Resources res = mStackView.getResources();
+        TaskStackLayoutAlgorithm stackLayout = mStackView.getStackAlgorithm();
+        TaskStackViewScroller stackScroller = mStackView.getScroller();
 
-        final int historyTransitionDuration = res.getInteger(
+        int historyTransitionDuration = res.getInteger(
                 R.integer.recents_history_transition_duration);
+        int startDelayIncr = 16;
 
         List<TaskView> taskViews = mStackView.getTaskViews();
         int taskViewCount = taskViews.size();
         for (int i = taskViewCount - 1; i >= 0; i--) {
-            final TaskView tv = taskViews.get(i);
-            postAnimationTrigger.addLastDecrementRunnable(new Runnable() {
-                @Override
-                public void run() {
-                    TaskViewAnimation taskAnimation = new TaskViewAnimation(
-                            historyTransitionDuration, PhoneStatusBar.ALPHA_IN);
-                    stackLayout.getStackTransform(tv.getTask(), stackScroller.getStackScroll(),
-                            mTmpTransform, null);
-                    mTmpTransform.alpha = 1f;
-                    mStackView.updateTaskViewToTransform(tv, mTmpTransform, taskAnimation);
-                }
-            });
+            TaskView tv = taskViews.get(i);
+            TaskViewAnimation taskAnimation = new TaskViewAnimation(startDelayIncr * i,
+                    historyTransitionDuration, mFastOutSlowInInterpolator);
+            stackLayout.getStackTransform(tv.getTask(), stackScroller.getStackScroll(),
+                    mTmpTransform, null);
+            mTmpTransform.alpha = 1f;
+            mStackView.updateTaskViewToTransform(tv, mTmpTransform, taskAnimation);
         }
     }
 }
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackLayoutAlgorithm.java b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackLayoutAlgorithm.java
index 93849dc5a373a..bb37c04f652c6 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackLayoutAlgorithm.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackLayoutAlgorithm.java
@@ -354,6 +354,7 @@ public class TaskStackLayoutAlgorithm {
         mStackBottomOffset = mSystemInsets.bottom + heightPadding;
         state.computeRects(mFreeformRect, mStackRect, taskStackBounds, widthPadding, heightPadding,
                 mStackBottomOffset);
+        // The history button will take the full un-padded header space above the stack
         mHistoryButtonRect.set(mStackRect.left, mStackRect.top - heightPadding,
                 mStackRect.right, mStackRect.top + mFocusedPeekHeight);
 
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 7423b78a9cb54..1c545c8af4e41 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java
@@ -64,6 +64,7 @@ import com.android.systemui.recents.events.ui.DeleteTaskDataEvent;
 import com.android.systemui.recents.events.ui.DismissTaskViewEvent;
 import com.android.systemui.recents.events.ui.StackViewScrolledEvent;
 import com.android.systemui.recents.events.ui.TaskViewDismissedEvent;
+import com.android.systemui.recents.events.ui.UpdateBackgroundScrimEvent;
 import com.android.systemui.recents.events.ui.UpdateFreeformTaskViewVisibilityEvent;
 import com.android.systemui.recents.events.ui.UserInteractionEvent;
 import com.android.systemui.recents.events.ui.dragndrop.DragDropTargetChangedEvent;
@@ -74,11 +75,13 @@ import com.android.systemui.recents.events.ui.focus.DismissFocusedTaskViewEvent;
 import com.android.systemui.recents.events.ui.focus.FocusNextTaskViewEvent;
 import com.android.systemui.recents.events.ui.focus.FocusPreviousTaskViewEvent;
 import com.android.systemui.recents.misc.DozeTrigger;
+import com.android.systemui.recents.misc.ReferenceCountedTrigger;
 import com.android.systemui.recents.misc.SystemServicesProxy;
 import com.android.systemui.recents.misc.Utilities;
 import com.android.systemui.recents.model.Task;
 import com.android.systemui.recents.model.TaskStack;
 
+import java.lang.ref.Reference;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -1117,12 +1120,19 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         // We can get spurious measure passes with the old bounds when docking, and since we are
         // using the current stack bounds during drag and drop, don't overwrite them until we
         // actually get new bounds
+        boolean requiresLayout = false;
         if (!taskStackBounds.equals(mStableStackBounds)) {
             mStableStackBounds.set(taskStackBounds);
             mStackBounds.set(taskStackBounds);
+            requiresLayout = true;
+        }
+        if (!systemInsets.equals(mLayoutAlgorithm.mSystemInsets)) {
+            mLayoutAlgorithm.setSystemInsets(systemInsets);
+            requiresLayout = true;
+        }
+        if (requiresLayout) {
+            requestLayout();
         }
-        mLayoutAlgorithm.setSystemInsets(systemInsets);
-        requestLayout();
     }
 
     /**
@@ -1235,7 +1245,7 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         // Update the history button visibility
         if (shouldShowHistoryButton() &&
                 mStackScroller.getStackScroll() < SHOW_HISTORY_BUTTON_SCROLL_THRESHOLD) {
-            EventBus.getDefault().send(new ShowHistoryButtonEvent());
+            EventBus.getDefault().send(new ShowHistoryButtonEvent(false /* translate */));
         } else {
             EventBus.getDefault().send(new HideHistoryButtonEvent());
         }
@@ -1468,13 +1478,15 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
             relayoutTaskViewsOnNextFrame(animation);
         }
 
-        if (shouldShowHistoryButton() &&
-                prevScroll > SHOW_HISTORY_BUTTON_SCROLL_THRESHOLD &&
-                curScroll <= SHOW_HISTORY_BUTTON_SCROLL_THRESHOLD) {
-            EventBus.getDefault().send(new ShowHistoryButtonEvent());
-        } else if (prevScroll < HIDE_HISTORY_BUTTON_SCROLL_THRESHOLD &&
-                curScroll >= HIDE_HISTORY_BUTTON_SCROLL_THRESHOLD) {
-            EventBus.getDefault().send(new HideHistoryButtonEvent());
+        if (mEnterAnimationComplete) {
+            if (shouldShowHistoryButton() &&
+                    prevScroll > SHOW_HISTORY_BUTTON_SCROLL_THRESHOLD &&
+                    curScroll <= SHOW_HISTORY_BUTTON_SCROLL_THRESHOLD) {
+                EventBus.getDefault().send(new ShowHistoryButtonEvent(true /* translate */));
+            } else if (prevScroll < HIDE_HISTORY_BUTTON_SCROLL_THRESHOLD &&
+                    curScroll >= HIDE_HISTORY_BUTTON_SCROLL_THRESHOLD) {
+                EventBus.getDefault().send(new HideHistoryButtonEvent());
+            }
         }
     }
 
@@ -1753,11 +1765,19 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
     }
 
     public final void onBusEvent(ShowHistoryEvent event) {
-        mAnimationHelper.startShowHistoryAnimation(event.getAnimationTrigger());
+        ReferenceCountedTrigger postAnimTrigger = new ReferenceCountedTrigger();
+        postAnimTrigger.addLastDecrementRunnable(new Runnable() {
+            @Override
+            public void run() {
+                setVisibility(View.INVISIBLE);
+            }
+        });
+        mAnimationHelper.startShowHistoryAnimation(postAnimTrigger);
     }
 
     public final void onBusEvent(HideHistoryEvent event) {
-        mAnimationHelper.startHideHistoryAnimation(event.getAnimationTrigger());
+        setVisibility(View.VISIBLE);
+        mAnimationHelper.startHideHistoryAnimation();
     }
 
     /**
diff --git a/packages/SystemUI/src/com/android/systemui/recents/views/TaskViewAnimation.java b/packages/SystemUI/src/com/android/systemui/recents/views/TaskViewAnimation.java
index 363ad667bc7db..74b16d0a56748 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/views/TaskViewAnimation.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/views/TaskViewAnimation.java
@@ -45,6 +45,10 @@ public class TaskViewAnimation {
         this(0 /* startDelay */, duration, interpolator, listener);
     }
 
+    public TaskViewAnimation(int startDelay, int duration, Interpolator interpolator) {
+        this(startDelay, duration, interpolator, null);
+    }
+
     public TaskViewAnimation(int startDelay, int duration, Interpolator interpolator,
             Animator.AnimatorListener listener) {
         this.startDelay = startDelay;