Fix text overlap issue when flinging in ManageApplication

The issue is we have a background handler to find app size and set to
summary asynchronously. When flinging quickly, the view being request to
update by the background handler could be scrolled off screen already.
This change forces onPackageSizeChanged update to only happen when it's
not scrolling.

Change-Id: Ia7ccab776c3c789c8d4c0b55104b48e257b9cebf
Fixes: 76176014
Test: manually fling

src/com/android/settings/applications/manageapplications/ManageApplications.java

@@ -16,6 +16,7 @@
 
 package com.android.settings.applications.manageapplications;
 
+import static android.support.v7.widget.RecyclerView.SCROLL_STATE_IDLE;
 import static com.android.settings.applications.manageapplications.AppFilterRegistry
         .FILTER_APPS_ALL;
 import static com.android.settings.applications.manageapplications.AppFilterRegistry
@@ -50,6 +51,7 @@ import android.os.Environment;
 import android.os.UserHandle;
 import android.os.UserManager;
 import android.preference.PreferenceFrameLayout;
+import android.support.annotation.NonNull;
 import android.support.annotation.VisibleForTesting;
 import android.support.v7.widget.LinearLayoutManager;
 import android.support.v7.widget.RecyclerView;
@@ -844,11 +846,16 @@ public class ManageApplications extends InstrumentedFragment
         private boolean mHasReceivedBridgeCallback;
         private FileViewHolderController mExtraViewController;
 
-        // These two variables are used to remember and restore the last scroll position when this
+        // This is to remember and restore the last scroll position when this
         // fragment is paused. We need this special handling because app entries are added gradually
         // when we rebuild the list after the user made some changes, like uninstalling an app.
         private int mLastIndex = -1;
 
+        @VisibleForTesting
+        OnScrollListener mOnScrollListener;
+        private RecyclerView mRecyclerView;
+
+
         public ApplicationsAdapter(ApplicationsState state, ManageApplications manageApplications,
                 AppFilterItem appFilter, Bundle savedInstanceState) {
             setHasStableIds(true);
@@ -886,6 +893,22 @@ public class ManageApplications extends InstrumentedFragment
             }
         }
 
+        @Override
+        public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {
+            super.onAttachedToRecyclerView(recyclerView);
+            mRecyclerView = recyclerView;
+            mOnScrollListener = new OnScrollListener(this);
+            mRecyclerView.addOnScrollListener(mOnScrollListener);
+        }
+
+        @Override
+        public void onDetachedFromRecyclerView(@NonNull RecyclerView recyclerView) {
+            super.onDetachedFromRecyclerView(recyclerView);
+            mRecyclerView.removeOnScrollListener(mOnScrollListener);
+            mOnScrollListener = null;
+            mRecyclerView = null;
+        }
+
         public void setCompositeFilter(AppFilter compositeFilter) {
             mCompositeFilter = compositeFilter;
             rebuild();
@@ -1180,9 +1203,8 @@ public class ManageApplications extends InstrumentedFragment
                     rebuild();
                     return;
                 } else {
-                    notifyItemChanged(i);
+                    mOnScrollListener.postNotifyItemChange(i);
                 }
-
             }
         }
 
@@ -1310,13 +1332,39 @@ public class ManageApplications extends InstrumentedFragment
             return mExtraViewController != null
                     && mExtraViewController.shouldShow();
         }
+
+        public static class OnScrollListener extends RecyclerView.OnScrollListener {
+            private int mScrollState = SCROLL_STATE_IDLE;
+            private boolean mDelayNotifyDataChange;
+            private ApplicationsAdapter mAdapter;
+
+            public OnScrollListener(ApplicationsAdapter adapter) {
+                mAdapter = adapter;
+            }
+
+            @Override
+            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
+                mScrollState = newState;
+                if (mScrollState == SCROLL_STATE_IDLE && mDelayNotifyDataChange) {
+                    mDelayNotifyDataChange = false;
+                    mAdapter.notifyDataSetChanged();
+                }
+            }
+
+            public void postNotifyItemChange(int index) {
+                if (mScrollState == SCROLL_STATE_IDLE) {
+                    mAdapter.notifyItemChanged(index);
+                } else {
+                    mDelayNotifyDataChange = true;
+                }
+            }
+        }
     }
 
     private static class SummaryProvider implements SummaryLoader.SummaryProvider {
 
         private final Context mContext;
         private final SummaryLoader mLoader;
-        private ApplicationsState.Session mSession;
 
         private SummaryProvider(Context context, SummaryLoader loader) {
             mContext = context;

tests/robotests/src/com/android/settings/applications/manageapplications/ManageApplicationsTest.java

@@ -16,6 +16,8 @@
 
 package com.android.settings.applications.manageapplications;
 
+import static android.support.v7.widget.RecyclerView.SCROLL_STATE_DRAGGING;
+import static android.support.v7.widget.RecyclerView.SCROLL_STATE_IDLE;
 import static com.android.settings.applications.manageapplications.AppFilterRegistry.FILTER_APPS_ALL;
 import static com.android.settings.applications.manageapplications.ManageApplications.LIST_TYPE_MAIN;
 import static com.android.settings.applications.manageapplications.ManageApplications.LIST_TYPE_NOTIFICATION;
@@ -229,6 +231,40 @@ public class ManageApplicationsTest {
         verify(loadingViewController).showContent(true /* animate */);
     }
 
+    @Test
+    public void notifyItemChange_recyclerViewIdle_shouldNotify() {
+        final RecyclerView recyclerView = mock(RecyclerView.class);
+        final ManageApplications.ApplicationsAdapter adapter =
+                spy(new ManageApplications.ApplicationsAdapter(mState,
+                        mock(ManageApplications.class),
+                        AppFilterRegistry.getInstance().get(FILTER_APPS_ALL), new Bundle()));
+
+        adapter.onAttachedToRecyclerView(recyclerView);
+        adapter.mOnScrollListener.onScrollStateChanged(recyclerView, SCROLL_STATE_IDLE);
+        adapter.mOnScrollListener.postNotifyItemChange(0 /* index */);
+
+        verify(adapter).notifyItemChanged(0);
+    }
+
+    @Test
+    public void notifyItemChange_recyclerViewScrolling_shouldNotifyWhenIdle() {
+        final RecyclerView recyclerView = mock(RecyclerView.class);
+        final ManageApplications.ApplicationsAdapter adapter =
+                spy(new ManageApplications.ApplicationsAdapter(mState,
+                        mock(ManageApplications.class),
+                        AppFilterRegistry.getInstance().get(FILTER_APPS_ALL), new Bundle()));
+
+        adapter.onAttachedToRecyclerView(recyclerView);
+        adapter.mOnScrollListener.onScrollStateChanged(recyclerView, SCROLL_STATE_DRAGGING);
+        adapter.mOnScrollListener.postNotifyItemChange(0 /* index */);
+
+        verify(adapter, never()).notifyItemChanged(0);
+        verify(adapter, never()).notifyDataSetChanged();
+
+        adapter.mOnScrollListener.onScrollStateChanged(recyclerView, SCROLL_STATE_IDLE);
+        verify(adapter).notifyDataSetChanged();
+    }
+
     private void setUpOptionMenus() {
         when(mMenu.findItem(anyInt())).thenAnswer(invocation -> {
             final Object[] args = invocation.getArguments();