am e0325fe9: Merge "Don\'t reload the layout every time we enter Recents. (Bug 18160176)" into lmp-mr1-dev

* commit 'e0325fe956c2a33b79added92f0e53be2246506a':
  Don't reload the layout every time we enter Recents. (Bug 18160176)

packages/SystemUI/src/com/android/systemui/recents/AlternateRecentsComponent.java

@@ -54,7 +54,7 @@ import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 /** A proxy implementation for the recents component */
-public class AlternateRecentsComponent {
+public class AlternateRecentsComponent implements ActivityOptions.OnAnimationStartedListener {
 
     final public static String EXTRA_FROM_HOME = "recents.triggeredOverHome";
     final public static String EXTRA_FROM_SEARCH_HOME = "recents.triggeredOverSearchHome";
@@ -62,7 +62,9 @@ public class AlternateRecentsComponent {
     final public static String EXTRA_FROM_TASK_ID = "recents.activeTaskId";
     final public static String EXTRA_TRIGGERED_FROM_ALT_TAB = "recents.triggeredFromAltTab";
     final public static String EXTRA_TRIGGERED_FROM_HOME_KEY = "recents.triggeredFromHomeKey";
+    final public static String EXTRA_REUSE_TASK_STACK_VIEWS = "recents.reuseTaskStackViews";
 
+    final public static String ACTION_START_ENTER_ANIMATION = "action_start_enter_animation";
     final public static String ACTION_TOGGLE_RECENTS_ACTIVITY = "action_toggle_recents_activity";
     final public static String ACTION_HIDE_RECENTS_ACTIVITY = "action_hide_recents_activity";
 
@@ -77,7 +79,10 @@ public class AlternateRecentsComponent {
     Context mContext;
     LayoutInflater mInflater;
     SystemServicesProxy mSystemServicesProxy;
+    Handler mHandler;
     boolean mBootCompleted;
+    boolean mStartAnimationTriggered;
+    boolean mCanReuseTaskStackViews = true;
 
     // Task launching
     RecentsConfiguration mConfig;
@@ -103,6 +108,7 @@ public class AlternateRecentsComponent {
         mInflater = LayoutInflater.from(context);
         mContext = context;
         mSystemServicesProxy = new SystemServicesProxy(context);
+        mHandler = new Handler();
         mTaskStackBounds = new Rect();
     }
 
@@ -128,7 +134,7 @@ public class AlternateRecentsComponent {
         }
 
         // When we start, preload the metadata associated with the previous tasks
-        RecentsTaskLoader.getInstance().preload(mContext);
+        RecentsTaskLoader.getInstance().preload(mContext, RecentsTaskLoader.ALL_TASKS);
     }
 
     public void onBootCompleted() {
@@ -176,7 +182,9 @@ public class AlternateRecentsComponent {
     }
 
     public void onPreloadRecents() {
-        // Do nothing
+        // When we start, preload the metadata associated with the previous tasks
+        RecentsTaskLoader.getInstance().preload(mContext,
+                Constants.Values.RecentsTaskLoader.PreloadFirstTasksCount);
     }
 
     public void onCancelPreloadingRecents() {
@@ -186,7 +194,7 @@ public class AlternateRecentsComponent {
     void showRelativeAffiliatedTask(boolean showNextTask) {
         RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
         TaskStack stack = loader.getTaskStack(mSystemServicesProxy, mContext.getResources(),
-                -1, -1, false, true, null, null);
+                -1, -1, RecentsTaskLoader.ALL_TASKS, false, true, null, null);
         // Return early if there are no tasks
         if (stack.getTaskCount() == 0) return;
 
@@ -251,6 +259,8 @@ public class AlternateRecentsComponent {
     }
 
     public void onConfigurationChanged(Configuration newConfig) {
+        // Don't reuse task stack views if the configuration changes
+        mCanReuseTaskStackViews = false;
         // Reload the header bar layout
         reloadHeaderBarLayout();
     }
@@ -364,23 +374,28 @@ public class AlternateRecentsComponent {
      * Creates the activity options for a unknown state->recents transition.
      */
     ActivityOptions getUnknownTransitionActivityOptions() {
+        mStartAnimationTriggered = false;
         return ActivityOptions.makeCustomAnimation(mContext,
                 R.anim.recents_from_unknown_enter,
-                R.anim.recents_from_unknown_exit);
+                R.anim.recents_from_unknown_exit,
+                mHandler, this);
     }
 
     /**
      * Creates the activity options for a home->recents transition.
      */
     ActivityOptions getHomeTransitionActivityOptions(boolean fromSearchHome) {
+        mStartAnimationTriggered = false;
         if (fromSearchHome) {
             return ActivityOptions.makeCustomAnimation(mContext,
                     R.anim.recents_from_search_launcher_enter,
-                    R.anim.recents_from_search_launcher_exit);
+                    R.anim.recents_from_search_launcher_exit,
+                    mHandler, this);
         }
         return ActivityOptions.makeCustomAnimation(mContext,
                 R.anim.recents_from_launcher_enter,
-                R.anim.recents_from_launcher_exit);
+                R.anim.recents_from_launcher_exit,
+                mHandler, this);
     }
 
     /**
@@ -408,9 +423,10 @@ public class AlternateRecentsComponent {
                 c.setBitmap(null);
             }
 
+            mStartAnimationTriggered = false;
             return ActivityOptions.makeThumbnailAspectScaleDownAnimation(mStatusBarView,
                     thumbnail, toTaskRect.left, toTaskRect.top, toTaskRect.width(),
-                    toTaskRect.height(), null);
+                    toTaskRect.height(), this);
         }
 
         // If both the screenshot and thumbnail fails, then just fall back to the default transition
@@ -423,7 +439,7 @@ public class AlternateRecentsComponent {
         // Get the stack of tasks that we are animating into
         RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
         TaskStack stack = loader.getTaskStack(mSystemServicesProxy, mContext.getResources(),
-                runningTaskId, -1, false, isTopTaskHome, null, null);
+                runningTaskId, -1, RecentsTaskLoader.ALL_TASKS, false, isTopTaskHome, null, null);
         if (stack.getTaskCount() == 0) {
             return null;
         }
@@ -529,11 +545,13 @@ public class AlternateRecentsComponent {
         }
         intent.putExtra(EXTRA_TRIGGERED_FROM_ALT_TAB, mTriggeredFromAltTab);
         intent.putExtra(EXTRA_FROM_TASK_ID, (topTask != null) ? topTask.id : -1);
+        intent.putExtra(EXTRA_REUSE_TASK_STACK_VIEWS, mCanReuseTaskStackViews);
         if (opts != null) {
             mContext.startActivityAsUser(intent, opts.toBundle(), UserHandle.CURRENT);
         } else {
             mContext.startActivityAsUser(intent, UserHandle.CURRENT);
         }
+        mCanReuseTaskStackViews = true;
     }
 
     /** Sets the RecentsComponent callbacks. */
@@ -547,4 +565,42 @@ public class AlternateRecentsComponent {
             sRecentsComponentCallbacks.onVisibilityChanged(visible);
         }
     }
+
+    /**** OnAnimationStartedListener Implementation ****/
+
+    @Override
+    public void onAnimationStarted() {
+        // Notify recents to start the enter animation
+        if (!mStartAnimationTriggered) {
+            // There can be a race condition between the start animation callback and
+            // the start of the new activity (where we register the receiver that listens
+            // to this broadcast, so we add our own receiver and if that gets called, then
+            // we know the activity has not yet started and we can retry sending the broadcast.
+            BroadcastReceiver fallbackReceiver = new BroadcastReceiver() {
+                @Override
+                public void onReceive(Context context, Intent intent) {
+                    if (getResultCode() == Activity.RESULT_OK) {
+                        mStartAnimationTriggered = true;
+                        return;
+                    }
+
+                    // Schedule for the broadcast to be sent again after some time
+                    mHandler.postDelayed(new Runnable() {
+                        @Override
+                        public void run() {
+                            onAnimationStarted();
+                        }
+                    }, 25);
+                }
+            };
+
+            // Send the broadcast to notify Recents that the animation has started
+            Intent intent = new Intent(ACTION_START_ENTER_ANIMATION);
+            intent.setPackage(mContext.getPackageName());
+            intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT |
+                    Intent.FLAG_RECEIVER_FOREGROUND);
+            mContext.sendOrderedBroadcastAsUser(intent, UserHandle.CURRENT, null,
+                    fallbackReceiver, null, Activity.RESULT_CANCELED, null, null);
+        }
+    }
 }

packages/SystemUI/src/com/android/systemui/recents/RecentsActivity.java

@@ -27,6 +27,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.SharedPreferences;
+import android.content.res.Configuration;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Looper;
@@ -142,6 +143,12 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
             } else if (action.equals(AlternateRecentsComponent.ACTION_TOGGLE_RECENTS_ACTIVITY)) {
                 // If we are toggling Recents, then first unfilter any filtered stacks first
                 dismissRecentsToFocusedTaskOrHome(true);
+            } else if (action.equals(AlternateRecentsComponent.ACTION_START_ENTER_ANIMATION)) {
+                // Trigger the enter animation
+                onEnterAnimationTriggered();
+                // Notify the fallback receiver that we have successfully got the broadcast
+                // See AlternateRecentsComponent.onAnimationStarted()
+                setResultCode(Activity.RESULT_OK);
             }
         }
     };
@@ -157,7 +164,8 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
                 // When the screen turns off, dismiss Recents to Home
                 dismissRecentsToHome(false);
                 // Start preloading some tasks in the background
-                RecentsTaskLoader.getInstance().preload(RecentsActivity.this);
+                RecentsTaskLoader.getInstance().preload(RecentsActivity.this,
+                        Constants.Values.RecentsTaskLoader.PreloadFirstTasksCount);
             } else if (action.equals(SearchManager.INTENT_GLOBAL_SEARCH_ACTIVITY_CHANGED)) {
                 // When the search activity changes, update the Search widget
                 refreshSearchWidget();
@@ -188,6 +196,8 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
                 AlternateRecentsComponent.EXTRA_FROM_TASK_ID, -1);
         mConfig.launchedWithAltTab = launchIntent.getBooleanExtra(
                 AlternateRecentsComponent.EXTRA_TRIGGERED_FROM_ALT_TAB, false);
+        mConfig.launchedReuseTaskStackViews = launchIntent.getBooleanExtra(
+                AlternateRecentsComponent.EXTRA_REUSE_TASK_STACK_VIEWS, false);
 
         // Load all the tasks
         RecentsTaskLoader loader = RecentsTaskLoader.getInstance();
@@ -397,8 +407,12 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
 
         // Update if we are getting a configuration change
         if (savedInstanceState != null) {
+            // Update RecentsConfiguration
+            mConfig = RecentsConfiguration.reinitialize(this,
+                    RecentsTaskLoader.getInstance().getSystemServicesProxy());
             mConfig.updateOnConfigurationChange();
-            onConfigurationChange();
+            // Trigger the enter animation
+            onEnterAnimationTriggered();
         }
 
         // Start listening for widget package changes if there is one bound, post it since we don't
@@ -428,19 +442,6 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
         }
     }
 
-    /** Called when the configuration changes. */
-    void onConfigurationChange() {
-        // Update RecentsConfiguration
-        mConfig = RecentsConfiguration.reinitialize(this,
-                RecentsTaskLoader.getInstance().getSystemServicesProxy());
-
-        // Try and start the enter animation (or restart it on configuration changed)
-        ReferenceCountedTrigger t = new ReferenceCountedTrigger(this, null, null, null);
-        mRecentsView.startEnterRecentsAnimation(new ViewAnimation.TaskViewEnterContext(t));
-        // Animate the SystemUI scrim views
-        mScrimViews.startEnterRecentsAnimation();
-    }
-
     /** Handles changes to the activity visibility. */
     void onRecentsActivityVisibilityChanged(boolean visible) {
         if (!visible) {
@@ -474,6 +475,7 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
         IntentFilter filter = new IntentFilter();
         filter.addAction(AlternateRecentsComponent.ACTION_HIDE_RECENTS_ACTIVITY);
         filter.addAction(AlternateRecentsComponent.ACTION_TOGGLE_RECENTS_ACTIVITY);
+        filter.addAction(AlternateRecentsComponent.ACTION_START_ENTER_ANIMATION);
         registerReceiver(mServiceBroadcastReceiver, filter);
 
         // Register any broadcast receivers for the task loader
@@ -492,8 +494,8 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
     protected void onStop() {
         super.onStop();
 
-        // Remove all the views
+        // Notify the views that we are no longer visible
-        mRecentsView.removeAllTaskStacks();
+        mRecentsView.onRecentsHidden();
 
         // Unregister the RecentsService receiver
         unregisterReceiver(mServiceBroadcastReceiver);
@@ -515,8 +517,7 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
         }
     }
 
-    @Override
+    public void onEnterAnimationTriggered() {
-    public void onEnterAnimationComplete() {
         // Try and start the enter animation (or restart it on configuration changed)
         ReferenceCountedTrigger t = new ReferenceCountedTrigger(this, null, null, null);
         mRecentsView.startEnterRecentsAnimation(new ViewAnimation.TaskViewEnterContext(t));
@@ -584,7 +585,6 @@ public class RecentsActivity extends Activity implements RecentsView.RecentsView
 
     /** Called when debug mode is triggered */
     public void onDebugModeTriggered() {
-
         if (mConfig.developerOptionsEnabled) {
             SharedPreferences settings = getSharedPreferences(getPackageName(), 0);
             if (settings.getBoolean(Constants.Values.App.Key_DebugModeEnabled, false)) {

packages/SystemUI/src/com/android/systemui/recents/RecentsConfiguration.java

@@ -115,8 +115,8 @@ public class RecentsConfiguration {
     public boolean launchedWithAltTab;
     public boolean launchedWithNoRecentTasks;
     public boolean launchedFromAppWithThumbnail;
-    public boolean launchedFromAppWithScreenshot;
     public boolean launchedFromHome;
+    public boolean launchedReuseTaskStackViews;
     public int launchedToTaskId;
 
     /** Misc **/
@@ -308,6 +308,7 @@ public class RecentsConfiguration {
         launchedWithNoRecentTasks = false;
         launchedFromAppWithThumbnail = false;
         launchedFromHome = false;
+        launchedReuseTaskStackViews = false;
         launchedToTaskId = -1;
     }
 

packages/SystemUI/src/com/android/systemui/recents/misc/DozeTrigger.java

@@ -82,4 +82,9 @@ public class DozeTrigger {
     public boolean hasTriggered() {
         return mHasTriggered;
     }
+
+    /** Resets the doze trigger state. */
+    public void resetTrigger() {
+        mHasTriggered = false;
+    }
 }

packages/SystemUI/src/com/android/systemui/recents/model/RecentsTaskLoader.java

@@ -260,6 +260,7 @@ public class RecentsTaskLoader {
     private static final String TAG = "RecentsTaskLoader";
 
     static RecentsTaskLoader sInstance;
+    public static final int ALL_TASKS = -1;
 
     SystemServicesProxy mSystemServicesProxy;
     DrawableLruCache mApplicationIconCache;
@@ -326,10 +327,9 @@ public class RecentsTaskLoader {
 
     /** Gets the list of recent tasks, ordered from back to front. */
     private static List<ActivityManager.RecentTaskInfo> getRecentTasks(SystemServicesProxy ssp,
-            boolean isTopTaskHome) {
+            int numTasksToLoad, boolean isTopTaskHome) {
-        RecentsConfiguration config = RecentsConfiguration.getInstance();
         List<ActivityManager.RecentTaskInfo> tasks =
-                ssp.getRecentTasks(config.maxNumTasksToLoad, UserHandle.CURRENT.getIdentifier(),
+                ssp.getRecentTasks(numTasksToLoad, UserHandle.CURRENT.getIdentifier(),
                         isTopTaskHome);
         Collections.reverse(tasks);
         return tasks;
@@ -416,7 +416,8 @@ public class RecentsTaskLoader {
         ArrayList<Task.TaskKey> taskKeys = new ArrayList<Task.TaskKey>();
         ArrayList<Task> tasksToLoad = new ArrayList<Task>();
         TaskStack stack = getTaskStack(mSystemServicesProxy, context.getResources(),
-                -1, preloadCount, true, isTopTaskHome, taskKeys, tasksToLoad);
+                -1, preloadCount, RecentsTaskLoader.ALL_TASKS, true, isTopTaskHome, taskKeys,
+                tasksToLoad);
         SpaceNode root = new SpaceNode();
         root.setStack(stack);
 
@@ -428,10 +429,10 @@ public class RecentsTaskLoader {
     }
 
     /** Preloads the set of recent tasks (not including thumbnails). */
-    public void preload(Context context) {
+    public void preload(Context context, int numTasksToPreload) {
         ArrayList<Task> tasksToLoad = new ArrayList<Task>();
         getTaskStack(mSystemServicesProxy, context.getResources(),
-                -1, -1, true, true, null, tasksToLoad);
+                -1, -1, numTasksToPreload, true, true, null, tasksToLoad);
 
         // Start the task loader and add all the tasks we need to load
         mLoadQueue.addTasks(tasksToLoad);
@@ -440,11 +441,13 @@ public class RecentsTaskLoader {
 
     /** Creates a lightweight stack of the current recent tasks, without thumbnails and icons. */
     public synchronized TaskStack getTaskStack(SystemServicesProxy ssp, Resources res,
-            int preloadTaskId, int preloadTaskCount,
+            int preloadTaskId, int preloadTaskCount, int loadTaskCount,
             boolean loadTaskThumbnails, boolean isTopTaskHome,
             List<Task.TaskKey> taskKeysOut, List<Task> tasksToLoadOut) {
         RecentsConfiguration config = RecentsConfiguration.getInstance();
-        List<ActivityManager.RecentTaskInfo> tasks = getRecentTasks(ssp, isTopTaskHome);
+        List<ActivityManager.RecentTaskInfo> tasks = getRecentTasks(ssp,
+                (loadTaskCount == ALL_TASKS ? config.maxNumTasksToLoad : loadTaskCount),
+                isTopTaskHome);
         HashMap<Task.ComponentNameKey, ActivityInfoHandle> activityInfoCache =
                 new HashMap<Task.ComponentNameKey, ActivityInfoHandle>();
         ArrayList<Task> tasksToAdd = new ArrayList<Task>();

packages/SystemUI/src/com/android/systemui/recents/views/RecentsView.java

@@ -95,42 +95,57 @@ public class RecentsView extends FrameLayout implements TaskStackView.TaskStackV
 
     /** Set/get the bsp root node */
     public void setTaskStacks(ArrayList<TaskStack> stacks) {
-        // Remove all TaskStackViews (but leave the search bar)
+        int numStacks = stacks.size();
+
+        // Make a list of the stack view children only
+        ArrayList<TaskStackView> stackViews = new ArrayList<TaskStackView>();
         int childCount = getChildCount();
-        for (int i = childCount - 1; i >= 0; i--) {
+        for (int i = 0; i < childCount; i++) {
-            View v = getChildAt(i);
+            View child = getChildAt(i);
-            if (v != mSearchBar) {
+            if (child != mSearchBar) {
-                removeViewAt(i);
+                stackViews.add((TaskStackView) child);
             }
         }
 
-        // Create and add all the stacks for this partition of space.
+        // Remove all/extra stack views
+        int numTaskStacksToKeep = 0; // Keep no tasks if we are recreating the layout
+        if (mConfig.launchedReuseTaskStackViews) {
+            numTaskStacksToKeep = Math.min(childCount, numStacks);
+        }
+        for (int i = stackViews.size() - 1; i >= numTaskStacksToKeep; i--) {
+            removeView(stackViews.get(i));
+            stackViews.remove(i);
+        }
+
+        // Update the stack views that we are keeping
+        for (int i = 0; i < numTaskStacksToKeep; i++) {
+            stackViews.get(i).setStack(stacks.get(i));
+        }
+
+        // Add remaining/recreate stack views
         mStacks = stacks;
-        int numStacks = mStacks.size();
+        for (int i = stackViews.size(); i < numStacks; i++) {
-        for (int i = 0; i < numStacks; i++) {
+            TaskStack stack = stacks.get(i);
-            TaskStack stack = mStacks.get(i);
             TaskStackView stackView = new TaskStackView(getContext(), stack);
             stackView.setCallbacks(this);
-            // Enable debug mode drawing
-            if (mConfig.debugModeEnabled) {
-                stackView.setDebugOverlay(mDebugOverlay);
-            }
             addView(stackView);
         }
 
+        // Enable debug mode drawing on all the stacks if necessary
+        if (mConfig.debugModeEnabled) {
+            for (int i = childCount - 1; i >= 0; i--) {
+                View v = getChildAt(i);
+                if (v != mSearchBar) {
+                    TaskStackView stackView = (TaskStackView) v;
+                    stackView.setDebugOverlay(mDebugOverlay);
+                }
+            }
+        }
+
         // Reset the launched state
         mAlreadyLaunchingTask = false;
-    }
+        // Trigger a new layout
-
+        requestLayout();
-    /** Removes all the task stack views from this recents view. */
-    public void removeAllTaskStacks() {
-        int childCount = getChildCount();
-        for (int i = childCount - 1; i >= 0; i--) {
-            View child = getChildAt(i);
-            if (child != mSearchBar) {
-                removeViewAt(i);
-            }
-        }
     }
 
     /** Launches the focused task from the first stack if possible */
@@ -529,6 +544,19 @@ public class RecentsView extends FrameLayout implements TaskStackView.TaskStackV
         mCb.onAllTaskViewsDismissed();
     }
 
+    /** Final callback after Recents is finally hidden. */
+    public void onRecentsHidden() {
+        // Notify each task stack view
+        int childCount = getChildCount();
+        for (int i = 0; i < childCount; i++) {
+            View child = getChildAt(i);
+            if (child != mSearchBar) {
+                TaskStackView stackView = (TaskStackView) child;
+                stackView.onRecentsHidden();
+            }
+        }
+    }
+
     @Override
     public void onTaskStackFilterTriggered() {
         // Hide the search bar

packages/SystemUI/src/com/android/systemui/recents/views/TaskStackView.java

@@ -40,6 +40,7 @@ import com.android.systemui.recents.model.TaskStack;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 
 
 /* The visual representation of a task stack view */
@@ -99,25 +100,11 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         }
     };
 
-    // A convenience runnable to return all views to the pool
-    Runnable mReturnAllViewsToPoolRunnable = new Runnable() {
-        @Override
-        public void run() {
-            int childCount = getChildCount();
-            for (int i = childCount - 1; i >= 0; i--) {
-                TaskView tv = (TaskView) getChildAt(i);
-                mViewPool.returnViewToPool(tv);
-                // Also hide the view since we don't need it anymore
-                tv.setVisibility(View.INVISIBLE);
-            }
-        }
-    };
-
     public TaskStackView(Context context, TaskStack stack) {
         super(context);
+        // Set the stack first
+        setStack(stack);
         mConfig = RecentsConfiguration.getInstance();
-        mStack = stack;
-        mStack.setCallbacks(this);
         mViewPool = new ViewPool<TaskView, Task>(context, this);
         mInflater = LayoutInflater.from(context);
         mLayoutAlgorithm = new TaskStackViewLayoutAlgorithm(mConfig);
@@ -143,11 +130,62 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         mCb = cb;
     }
 
+    /** Sets the task stack */
+    void setStack(TaskStack stack) {
+        // Unset the old stack
+        if (mStack != null) {
+            mStack.setCallbacks(null);
+
+            // Return all existing views to the pool
+            reset();
+            // Layout again with the new stack
+            requestLayout();
+        }
+
+        // Set the new stack
+        mStack = stack;
+        if (mStack != null) {
+            mStack.setCallbacks(this);
+        }
+    }
+
     /** Sets the debug overlay */
     public void setDebugOverlay(DebugOverlayView overlay) {
         mDebugOverlay = overlay;
     }
 
+    /** Resets this TaskStackView for reuse. */
+    void reset() {
+        // Return all the views to the pool
+        int childCount = getChildCount();
+        for (int i = childCount - 1; i >= 0; i--) {
+            TaskView tv = (TaskView) getChildAt(i);
+            mViewPool.returnViewToPool(tv);
+        }
+
+        // Mark each task view for relayout
+        if (mViewPool != null) {
+            Iterator<TaskView> iter = mViewPool.poolViewIterator();
+            if (iter != null) {
+                while (iter.hasNext()) {
+                    TaskView tv = iter.next();
+                    tv.reset();
+                }
+            }
+        }
+
+        // Reset the stack state
+        resetFocusedTask();
+        mStackViewsDirty = true;
+        mStackViewsClipDirty = true;
+        mAwaitingFirstLayout = true;
+        mPrevAccessibilityFocusedIndex = -1;
+        if (mUIDozeTrigger != null) {
+            mUIDozeTrigger.stopDozing();
+            mUIDozeTrigger.resetTrigger();
+        }
+    }
+
     /** Requests that the views be synchronized with the model */
     void requestSynchronizeStackViewsWithModel() {
         requestSynchronizeStackViewsWithModel(0);
@@ -510,6 +548,16 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         tv.dismissTask();
     }
 
+    /** Resets the focused task. */
+    void resetFocusedTask() {
+        if (mFocusedTaskIndex > -1) {
+            Task t = mStack.getTasks().get(mFocusedTaskIndex);
+            TaskView tv = getChildViewForTask(t);
+            tv.unsetFocusedTask();
+        }
+        mFocusedTaskIndex = -1;
+    }
+
     @Override
     public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
         super.onInitializeAccessibilityEvent(event);
@@ -543,6 +591,8 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
 
     @Override
     public void computeScroll() {
+        if (mStack == null) return;
+
         mStackScroller.computeScroll();
         // Synchronize the views
         synchronizeStackViewsWithModel();
@@ -758,9 +808,6 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
             TaskView tv = (TaskView) getChildAt(i);
             tv.startExitToHomeAnimation(ctx);
         }
-
-        // Add a runnable to the post animation ref counter to clear all the views
-        ctx.postAnimationTrigger.addLastDecrementRunnable(mReturnAllViewsToPoolRunnable);
     }
 
     /** Animates a task view in this stack as it launches. */
@@ -780,6 +827,12 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         }
     }
 
+    /** Final callback after Recents is finally hidden. */
+    void onRecentsHidden() {
+        reset();
+        setStack(null);
+    }
+
     public boolean isTransformedTouchPointInView(float x, float y, View child) {
         return isTransformedTouchPointInView(x, y, child, null);
     }
@@ -944,20 +997,23 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
 
         // Reset the view properties
         tv.resetViewProperties();
+
+        // Reset the clip state of the task view
+        tv.setClipViewInStack(false);
     }
 
     @Override
     public void prepareViewToLeavePool(TaskView tv, Task task, boolean isNewView) {
+        // It is possible for a view to be returned to the view pool before it is laid out,
+        // which means that we will need to relayout the view when it is first used next.
+        boolean requiresRelayout = tv.getWidth() <= 0 && !isNewView;
+
         // Rebind the task and request that this task's data be filled into the TaskView
         tv.onTaskBound(task);
 
         // Load the task data
         RecentsTaskLoader.getInstance().loadTaskData(task);
 
-        // Sanity check, the task view should always be clipping against the stack at this point,
-        // but just in case, re-enable it here
-        tv.setClipViewInStack(true);
-
         // If the doze trigger has already fired, then update the state for this task view
         if (mUIDozeTrigger.hasTriggered()) {
             tv.setNoUserInteractionState();
@@ -985,13 +1041,17 @@ public class TaskStackView extends FrameLayout implements TaskStack.TaskStackCal
         // Add/attach the view to the hierarchy
         if (isNewView) {
             addView(tv, insertIndex);
-
-            // Set the callbacks and listeners for this new view
-            tv.setTouchEnabled(true);
-            tv.setCallbacks(this);
         } else {
             attachViewToParent(tv, insertIndex, tv.getLayoutParams());
+            if (requiresRelayout) {
+                tv.requestLayout();
+            }
         }
+
+        // Set the new state for this view, including the callbacks and view clipping
+        tv.setCallbacks(this);
+        tv.setTouchEnabled(true);
+        tv.setClipViewInStack(true);
     }
 
     @Override

packages/SystemUI/src/com/android/systemui/recents/views/TaskView.java

@@ -112,6 +112,14 @@ public class TaskView extends FrameLayout implements Task.TaskCallbacks,
         mCb = cb;
     }
 
+    /** Resets this TaskView for reuse. */
+    void reset() {
+        resetViewProperties();
+        resetNoUserInteractionState();
+        setClipViewInStack(false);
+        setCallbacks(null);
+    }
+
     /** Gets the task */
     Task getTask() {
         return mTask;
@@ -191,6 +199,7 @@ public class TaskView extends FrameLayout implements Task.TaskCallbacks,
     /** Resets this view's properties */
     void resetViewProperties() {
         setDim(0);
+        setLayerType(View.LAYER_TYPE_NONE, null);
         TaskViewTransform.reset(this);
     }
 
@@ -448,6 +457,11 @@ public class TaskView extends FrameLayout implements Task.TaskCallbacks,
         mHeaderView.setNoUserInteractionState();
     }
 
+    /** Resets the state tracking that the user has not interacted with the stack after a certain time. */
+    void resetNoUserInteractionState() {
+        mHeaderView.resetNoUserInteractionState();
+    }
+
     /** Dismisses this task. */
     void dismissTask() {
         // Animate out the view and call the callback

packages/SystemUI/src/com/android/systemui/recents/views/TaskViewHeader.java

@@ -263,6 +263,11 @@ public class TaskViewHeader extends FrameLayout {
         }
     }
 
+    /** Resets the state tracking that the user has not interacted with the stack after a certain time. */
+    void resetNoUserInteractionState() {
+        mDismissButton.setVisibility(View.INVISIBLE);
+    }
+
     @Override
     protected int[] onCreateDrawableState(int extraSpace) {
 

packages/SystemUI/src/com/android/systemui/recents/views/ViewPool.java

@@ -75,4 +75,12 @@ public class ViewPool<V, T> {
         mViewCreator.prepareViewToLeavePool(v, prepareData, isNewView);
         return v;
     }
+
+    /** Returns an iterator to the list of the views in the pool. */
+    Iterator<V> poolViewIterator() {
+        if (mPool != null) {
+            return mPool.iterator();
+        }
+        return null;
+    }
 }