Remove flicker when multiple apps are added/removed/updated on widget tray

Bug: 36718342

1.The flicker was also happening partially because notifyWidgetProviderChanged
callback also made the entire widget list to update in addition to
packageManager update.

2. Now that adapter calls notifyItemInserted, Removed, the recycler
view uses it's internal animation to elegantly move items or insert
them. (added benefit!)

3. Added tests for WidgetsListAdapterTest

$ adb shell am instrument -w -e class com.android.launcher3.widget.WidgetsListAdapterTest com.google.android.apps.nexuslauncher.tests/android.support.test.runner.AndroidJUnitRunner

com.android.launcher3.widget.WidgetsListAdapterTest:.

Time: 0.337

OK (6 test)

Change-Id: I0818d546532631bf889fae560118decff64ec5a4
Signed-off-by: Hyunyoung Song <hyunyoungs@google.com>

5 files changed, 350 insertions, 22 deletions

diff --git a/src/com/android/launcher3/widget/WidgetListRowEntry.java b/src/com/android/launcher3/widget/WidgetListRowEntry.java
index 3e89eeb9b..335b8c759 100644
--- a/src/com/android/launcher3/widget/WidgetListRowEntry.java
+++ b/src/com/android/launcher3/widget/WidgetListRowEntry.java
@@ -41,4 +41,8 @@ public class WidgetListRowEntry {
         this.widgets = items;
     }
 
+    @Override
+    public String toString() {
+        return pkgItem.packageName + ":" + widgets.size();
+    }
 }
diff --git a/src/com/android/launcher3/widget/WidgetsContainerView.java b/src/com/android/launcher3/widget/WidgetsContainerView.java
index 14a9d17ed..acec3dd3b 100644
--- a/src/com/android/launcher3/widget/WidgetsContainerView.java
+++ b/src/com/android/launcher3/widget/WidgetsContainerView.java
@@ -17,10 +17,12 @@
 package com.android.launcher3.widget;
 
 import android.content.Context;
+import android.content.pm.LauncherApps;
 import android.graphics.Point;
 import android.support.v7.widget.LinearLayoutManager;
 import android.util.AttributeSet;
 import android.util.Log;
+import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Toast;
@@ -31,8 +33,10 @@ import com.android.launcher3.DragSource;
 import com.android.launcher3.DropTarget.DragObject;
 import com.android.launcher3.ItemInfo;
 import com.android.launcher3.Launcher;
+import com.android.launcher3.LauncherAppState;
 import com.android.launcher3.R;
 import com.android.launcher3.Utilities;
+import com.android.launcher3.compat.AlphabeticIndexCompat;
 import com.android.launcher3.dragndrop.DragOptions;
 import com.android.launcher3.folder.Folder;
 import com.android.launcher3.model.PackageItemInfo;
@@ -74,7 +78,11 @@ public class WidgetsContainerView extends BaseContainerView
     public WidgetsContainerView(Context context, AttributeSet attrs, int defStyleAttr) {
         super(context, attrs, defStyleAttr);
         mLauncher = Launcher.getLauncher(context);
-        mAdapter = new WidgetsListAdapter(this, this, context);
+        LauncherAppState apps = LauncherAppState.getInstance(context);
+        mAdapter = new WidgetsListAdapter(context, LayoutInflater.from(context),
+                apps.getWidgetCache(), new AlphabeticIndexCompat(context), this, this,
+                new WidgetsDiffReporter(apps.getIconCache()));
+        mAdapter.setNotifyListener();
         if (LOGD) {
             Log.d(TAG, "WidgetsContainerView constructor");
         }
@@ -232,7 +240,6 @@ public class WidgetsContainerView extends BaseContainerView
      */
     public void setWidgets(MultiHashMap<PackageItemInfo, WidgetItem> model) {
         mAdapter.setWidgets(model);
-        mAdapter.notifyDataSetChanged();
 
         View loader = getContentView().findViewById(R.id.loader);
         if (loader != null) {
diff --git a/src/com/android/launcher3/widget/WidgetsDiffReporter.java b/src/com/android/launcher3/widget/WidgetsDiffReporter.java
new file mode 100644
index 000000000..d9c9ef9e3
--- /dev/null
+++ b/src/com/android/launcher3/widget/WidgetsDiffReporter.java
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2017 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.launcher3.widget;
+
+import android.util.Log;
+
+import com.android.launcher3.IconCache;
+import com.android.launcher3.model.PackageItemInfo;
+import com.android.launcher3.widget.WidgetsListAdapter.WidgetListRowEntryComparator;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+
+/**
+ * Do diff on widget's tray list items and call the {@link NotifyListener} methods accordingly.
+ */
+public class WidgetsDiffReporter {
+    private final boolean DEBUG = true;
+    private final String TAG = "WidgetsDiffReporter";
+    private final IconCache mIconCache;
+    private NotifyListener mListener;
+
+    public interface NotifyListener {
+        void notifyDataSetChanged();
+        void notifyItemChanged(int index);
+        void notifyItemInserted(int index);
+        void notifyItemRemoved(int index);
+    }
+
+    public WidgetsDiffReporter(IconCache iconCache) {
+        mIconCache = iconCache;
+    }
+
+    public void setListener(NotifyListener listener) {
+        mListener = listener;
+    }
+
+    public void process(ArrayList<WidgetListRowEntry> currentEntries,
+            ArrayList<WidgetListRowEntry> newEntries, WidgetListRowEntryComparator comparator) {
+        if (DEBUG) {
+            Log.d(TAG, "process oldEntries#=" + currentEntries.size()
+                    + " newEntries#=" + newEntries.size());
+        }
+        if (currentEntries.size() == 0 && newEntries.size() > 0) {
+            currentEntries.addAll(newEntries);
+            mListener.notifyDataSetChanged();
+            return;
+        }
+        ArrayList<WidgetListRowEntry> orgEntries =
+                (ArrayList<WidgetListRowEntry>) currentEntries.clone();
+        Iterator<WidgetListRowEntry> orgIter = orgEntries.iterator();
+        Iterator<WidgetListRowEntry> newIter = newEntries.iterator();
+
+        WidgetListRowEntry orgRowEntry = orgIter.next();
+        WidgetListRowEntry newRowEntry = newIter.next();
+
+        do {
+            int diff = comparePackageName(orgRowEntry, newRowEntry, comparator);
+            if (DEBUG) {
+                Log.d(TAG, String.format("diff=%d orgRowEntry (%s) newRowEntry (%s)",
+                        diff, orgRowEntry != null? orgRowEntry.toString() : null,
+                        newRowEntry != null? newRowEntry.toString() : null));
+            }
+            int index = -1;
+            if (diff < 0) {
+                index = currentEntries.indexOf(orgRowEntry);
+                mListener.notifyItemRemoved(index);
+                if (DEBUG) {
+                    Log.d(TAG, String.format("notifyItemRemoved called (%d)%s", index,
+                            orgRowEntry.titleSectionName));
+                }
+                currentEntries.remove(index);
+                orgRowEntry = orgIter.hasNext() ? orgIter.next() : null;
+            } else if (diff > 0) {
+                index = orgRowEntry != null? currentEntries.indexOf(orgRowEntry):
+                        currentEntries.size();
+                currentEntries.add(index, newRowEntry);
+                newRowEntry = newIter.hasNext() ? newIter.next() : null;
+                mListener.notifyItemInserted(index);
+                if (DEBUG) {
+                    Log.d(TAG, String.format("notifyItemInserted called (%d)%s", index,
+                            newRowEntry.titleSectionName));
+                }
+            } else {
+                // same package name but,
+                // did the icon, title, etc, change?
+                // or did the widget size and desc, span, etc change?
+                if (!isSamePackageItemInfo(orgRowEntry.pkgItem, newRowEntry.pkgItem) ||
+                        !orgRowEntry.widgets.equals(newRowEntry.widgets)) {
+                    index = currentEntries.indexOf(orgRowEntry);
+                    currentEntries.set(index, newRowEntry);
+                    mListener.notifyItemChanged(index);
+                    if (DEBUG) {
+                        Log.d(TAG, String.format("notifyItemChanged called (%d)%s", index,
+                                newRowEntry.titleSectionName));
+                    }
+                }
+                orgRowEntry = orgIter.hasNext() ? orgIter.next() : null;
+                newRowEntry = newIter.hasNext() ? newIter.next() : null;
+            }
+        } while(orgRowEntry != null || newRowEntry != null);
+    }
+
+    /**
+     * Compare package name using the same comparator as in {@link WidgetsListAdapter}.
+     * Also handle null row pointers.
+     */
+    private int comparePackageName(WidgetListRowEntry curRow, WidgetListRowEntry newRow,
+            WidgetListRowEntryComparator comparator) {
+        if (curRow == null && newRow == null) {
+            throw new IllegalStateException("Cannot compare PackageItemInfo if both rows are null.");
+        }
+
+        if (curRow == null && newRow != null) {
+            return 1; // new row needs to be inserted
+        } else if (curRow != null && newRow == null) {
+            return -1; // old row needs to be deleted
+        }
+        return comparator.compare(curRow, newRow);
+    }
+
+    private boolean isSamePackageItemInfo(PackageItemInfo curInfo, PackageItemInfo newInfo) {
+        return curInfo.iconBitmap.equals(newInfo.iconBitmap) &&
+                !mIconCache.isDefaultIcon(curInfo.iconBitmap, curInfo.user);
+    }
+}
diff --git a/src/com/android/launcher3/widget/WidgetsListAdapter.java b/src/com/android/launcher3/widget/WidgetsListAdapter.java
index a1eb0ab12..6b1800c67 100644
--- a/src/com/android/launcher3/widget/WidgetsListAdapter.java
+++ b/src/com/android/launcher3/widget/WidgetsListAdapter.java
@@ -21,9 +21,10 @@ import android.support.v7.widget.RecyclerView.Adapter;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
+import android.view.View.OnClickListener;
+import android.view.View.OnLongClickListener;
 import android.view.ViewGroup;
 
-import com.android.launcher3.LauncherAppState;
 import com.android.launcher3.R;
 import com.android.launcher3.WidgetPreviewLoader;
 import com.android.launcher3.compat.AlphabeticIndexCompat;
@@ -55,40 +56,67 @@ public class WidgetsListAdapter extends Adapter<WidgetsRowViewHolder> {
 
     private final WidgetPreviewLoader mWidgetPreviewLoader;
     private final LayoutInflater mLayoutInflater;
-
-    private final View.OnClickListener mIconClickListener;
-    private final View.OnLongClickListener mIconLongClickListener;
-
-    private final ArrayList<WidgetListRowEntry> mEntries = new ArrayList<>();
     private final AlphabeticIndexCompat mIndexer;
 
+    private final OnClickListener mIconClickListener;
+    private final OnLongClickListener mIconLongClickListener;
     private final int mIndent;
-
-    public WidgetsListAdapter(View.OnClickListener iconClickListener,
-            View.OnLongClickListener iconLongClickListener,
-            Context context) {
-        mLayoutInflater = LayoutInflater.from(context);
-        mWidgetPreviewLoader = LauncherAppState.getInstance(context).getWidgetCache();
-
-        mIndexer = new AlphabeticIndexCompat(context);
-
+    private ArrayList<WidgetListRowEntry> mEntries = new ArrayList<>();
+    private final WidgetsDiffReporter mDiffReporter;
+
+    public WidgetsListAdapter(Context context, LayoutInflater layoutInflater,
+            WidgetPreviewLoader widgetPreviewLoader, AlphabeticIndexCompat indexCompat,
+            OnClickListener iconClickListener, OnLongClickListener iconLongClickListener,
+            WidgetsDiffReporter diffReporter) {
+        mLayoutInflater = layoutInflater;
+        mWidgetPreviewLoader = widgetPreviewLoader;
+        mIndexer = indexCompat;
         mIconClickListener = iconClickListener;
         mIconLongClickListener = iconLongClickListener;
         mIndent = context.getResources().getDimensionPixelSize(R.dimen.widget_section_indent);
+        mDiffReporter = diffReporter;
     }
 
+    public void setNotifyListener() {
+        mDiffReporter.setListener(new WidgetsDiffReporter.NotifyListener() {
+            @Override
+            public void notifyDataSetChanged() {
+                WidgetsListAdapter.this.notifyDataSetChanged();
+            }
+
+            @Override
+            public void notifyItemChanged(int index) {
+                WidgetsListAdapter.this.notifyItemChanged(index);
+            }
+
+            @Override
+            public void notifyItemInserted(int index) {
+                WidgetsListAdapter.this.notifyItemInserted(index);
+            }
+
+            @Override
+            public void notifyItemRemoved(int index) {
+                WidgetsListAdapter.this.notifyItemRemoved(index);
+            }
+        });
+    }
+
+    /**
+     * Update the widget list.
+     */
     public void setWidgets(MultiHashMap<PackageItemInfo, WidgetItem> widgets) {
-        mEntries.clear();
-        WidgetItemComparator widgetComparator = new WidgetItemComparator();
+        ArrayList<WidgetListRowEntry> tempEntries = new ArrayList<>();
 
+        WidgetItemComparator widgetComparator = new WidgetItemComparator();
         for (Map.Entry<PackageItemInfo, ArrayList<WidgetItem>> entry : widgets.entrySet()) {
             WidgetListRowEntry row = new WidgetListRowEntry(entry.getKey(), entry.getValue());
             row.titleSectionName = mIndexer.computeSectionName(row.pkgItem.title);
             Collections.sort(row.widgets, widgetComparator);
-            mEntries.add(row);
+            tempEntries.add(row);
         }
-
-        Collections.sort(mEntries, new WidgetListRowEntryComparator());
+        WidgetListRowEntryComparator rowComparator = new WidgetListRowEntryComparator();
+        Collections.sort(tempEntries, rowComparator);
+        mDiffReporter.process(mEntries, tempEntries, rowComparator);
     }
 
     @Override
diff --git a/tests/src/com/android/launcher3/widget/WidgetsListAdapterTest.java b/tests/src/com/android/launcher3/widget/WidgetsListAdapterTest.java
new file mode 100644
index 000000000..40b65e4fb
--- /dev/null
+++ b/tests/src/com/android/launcher3/widget/WidgetsListAdapterTest.java
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2017 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.launcher3.widget;
+
+import android.appwidget.AppWidgetProviderInfo;
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.graphics.Bitmap;
+import android.support.test.InstrumentationRegistry;
+import android.support.test.filters.SmallTest;
+import android.support.test.runner.AndroidJUnit4;
+import android.view.LayoutInflater;
+
+import com.android.launcher3.IconCache;
+import com.android.launcher3.InvariantDeviceProfile;
+import com.android.launcher3.LauncherAppWidgetProviderInfo;
+import com.android.launcher3.WidgetPreviewLoader;
+import com.android.launcher3.compat.AlphabeticIndexCompat;
+import com.android.launcher3.compat.AppWidgetManagerCompat;
+import com.android.launcher3.model.PackageItemInfo;
+import com.android.launcher3.model.WidgetItem;
+import com.android.launcher3.util.MultiHashMap;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyInt;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class WidgetsListAdapterTest {
+
+    private final String TAG = "WidgetsListAdapterTest";
+
+    @Mock private LayoutInflater mMockLayoutInflater;
+    @Mock private WidgetPreviewLoader mMockWidgetCache;
+    @Mock private WidgetsDiffReporter.NotifyListener mListener;
+    @Mock private IconCache mIconCache;
+
+    private WidgetsListAdapter mAdapter;
+    private AlphabeticIndexCompat mIndexCompat;
+    private InvariantDeviceProfile mTestProfile;
+    private Context mContext;
+
+    @Before
+    public void setup() {
+        MockitoAnnotations.initMocks(this);
+        mContext = InstrumentationRegistry.getTargetContext();
+        mTestProfile = new InvariantDeviceProfile();
+        mTestProfile.numRows = 5;
+        mTestProfile.numColumns = 5;
+        mIndexCompat = new AlphabeticIndexCompat(mContext);
+        WidgetsDiffReporter reporter = new WidgetsDiffReporter(mIconCache);
+        reporter.setListener(mListener);
+        mAdapter = new WidgetsListAdapter(mContext, mMockLayoutInflater, mMockWidgetCache,
+                mIndexCompat, null, null, reporter);
+    }
+
+    @Test
+    public void test_notifyDataSetChanged() throws Exception {
+        mAdapter.setWidgets(generateSampleMap(1));
+        verify(mListener, times(1)).notifyDataSetChanged();
+    }
+
+    @Test
+    public void test_notifyItemInserted() throws Exception {
+        mAdapter.setWidgets(generateSampleMap(1));
+        mAdapter.setWidgets(generateSampleMap(2));
+        verify(mListener, times(1)).notifyDataSetChanged();
+        verify(mListener, times(1)).notifyItemInserted(1);
+    }
+
+    @Test
+    public void test_notifyItemRemoved() throws Exception {
+        mAdapter.setWidgets(generateSampleMap(2));
+        mAdapter.setWidgets(generateSampleMap(1));
+        verify(mListener, times(1)).notifyDataSetChanged();
+        verify(mListener, times(1)).notifyItemRemoved(1);
+    }
+
+    @Test
+    public void testNotifyItemChanged_PackageIconDiff() throws Exception {
+        mAdapter.setWidgets(generateSampleMap(1));
+        mAdapter.setWidgets(generateSampleMap(1));
+        verify(mListener, times(1)).notifyDataSetChanged();
+        verify(mListener, times(1)).notifyItemChanged(0);
+    }
+
+    @Test
+    public void testNotifyItemChanged_widgetItemInfoDiff() throws Exception {
+        // TODO: same package name but item number changed
+    }
+
+    @Test
+    public void testNotifyItemInsertedRemoved_hodgepodge() throws Exception {
+        // TODO: insert and remove combined.          curMap
+        // newMap [A, C, D]                           [A, B, E]
+        // B - C < 0, removed B from index 1          [A, E]
+        // E - C > 0, C inserted to index 1           [A, C, E]
+        // E - D > 0, D inserted to index 2           [A, C, D, E]
+        // E - null = -1, E deleted from index 3      [A, C, D]
+    }
+
+    /**
+     * Helper method to generate the sample widget model map that can be used for the tests
+     * @param num the number of WidgetItem the map should contain
+     * @return
+     */
+    private MultiHashMap<PackageItemInfo, WidgetItem> generateSampleMap(int num) {
+        MultiHashMap<PackageItemInfo, WidgetItem> newMap = new MultiHashMap();
+        if (num <= 0) return newMap;
+
+        PackageManager pm = mContext.getPackageManager();
+        AppWidgetManagerCompat widgetManager = AppWidgetManagerCompat.getInstance(mContext);
+        for (AppWidgetProviderInfo widgetInfo : widgetManager.getAllProviders(null)) {
+            WidgetItem wi = new WidgetItem(LauncherAppWidgetProviderInfo
+                    .fromProviderInfo(mContext, widgetInfo), pm, mTestProfile);
+
+            PackageItemInfo pInfo = new PackageItemInfo(wi.componentName.getPackageName());
+            pInfo.title = pInfo.packageName;
+            pInfo.user = wi.user;
+            pInfo.iconBitmap = Bitmap.createBitmap(10, 10, Bitmap.Config.ALPHA_8);
+            newMap.addToList(pInfo, wi);
+            if (newMap.size() == num) {
+                break;
+            }
+        }
+        return newMap;
+    }
+}