Unifying focus indicator handling for workspace and all-apps

Adding an abstract FocusIndicatorHelper based on FocusIndicatorView
which draws the background instead of using a dummy view.

Change-Id: Id560195323d2ddad8fcd77ba675cf3f4fd4a94ab

10 files changed, 424 insertions, 230 deletions

diff --git a/src/com/android/launcher3/FocusIndicatorView.java b/src/com/android/launcher3/FocusIndicatorView.java
deleted file mode 100644
index a835d9969..000000000
--- a/src/com/android/launcher3/FocusIndicatorView.java
+++ /dev/null
@@ -1,203 +0,0 @@
-/*
- * Copyright (C) 2011 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;
-
-import android.animation.Animator;
-import android.animation.PropertyValuesHolder;
-import android.content.Context;
-import android.graphics.Canvas;
-import android.util.AttributeSet;
-import android.util.Pair;
-import android.view.View;
-
-import com.android.launcher3.util.Thunk;
-
-public class FocusIndicatorView extends View implements View.OnFocusChangeListener {
-
-    // It can be any number >0. The view is resized using scaleX and scaleY.
-    static final int DEFAULT_LAYOUT_SIZE = 100;
-
-    private static final float MIN_VISIBLE_ALPHA = 0.2f;
-    private static final long ANIM_DURATION = 150;
-
-    private final int[] mIndicatorPos = new int[2];
-    private final int[] mTargetViewPos = new int[2];
-
-    private Animator mCurrentAnimation;
-    private ViewAnimState mTargetState;
-
-    private View mLastFocusedView;
-    private boolean mInitiated;
-    private final OnFocusChangeListener mHideIndicatorOnFocusListener;
-
-    private Pair<View, Boolean> mPendingCall;
-
-    public FocusIndicatorView(Context context) {
-        this(context, null);
-    }
-
-    public FocusIndicatorView(Context context, AttributeSet attrs) {
-        super(context, attrs);
-        setAlpha(0);
-        setBackgroundColor(getResources().getColor(R.color.focused_background));
-
-        mHideIndicatorOnFocusListener = new OnFocusChangeListener() {
-            @Override
-            public void onFocusChange(View v, boolean hasFocus) {
-                if (hasFocus) {
-                    endCurrentAnimation();
-                    setAlpha(0);
-                }
-            }
-        };
-    }
-
-    @Override
-    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
-        super.onSizeChanged(w, h, oldw, oldh);
-
-        // Redraw if it is already showing. This avoids a bug where the height changes by a small
-        // amount on connecting/disconnecting a bluetooth keyboard.
-        if (mLastFocusedView != null) {
-            mPendingCall = Pair.create(mLastFocusedView, Boolean.TRUE);
-            invalidate();
-        }
-    }
-
-    /**
-     * Sets the alpha of this FocusIndicatorView to 0 when a view with this listener receives focus.
-     */
-    public View.OnFocusChangeListener getHideIndicatorOnFocusListener() {
-        return mHideIndicatorOnFocusListener;
-    }
-
-    @Override
-    public void onFocusChange(View v, boolean hasFocus) {
-        mPendingCall = null;
-        if (!mInitiated && (getWidth() == 0)) {
-            // View not yet laid out. Wait until the view is ready to be drawn, so that be can
-            // get the location on screen.
-            mPendingCall = Pair.create(v, hasFocus);
-            invalidate();
-            return;
-        }
-
-        if (!mInitiated) {
-            // The parent view should always the a parent of the target view.
-            computeLocationRelativeToParent(this, (View) getParent(), mIndicatorPos);
-            mInitiated = true;
-        }
-
-        if (hasFocus) {
-            int indicatorWidth = getWidth();
-            int indicatorHeight = getHeight();
-
-            endCurrentAnimation();
-            ViewAnimState nextState = new ViewAnimState();
-            nextState.scaleX = v.getScaleX() * v.getWidth() / indicatorWidth;
-            nextState.scaleY = v.getScaleY() * v.getHeight() / indicatorHeight;
-
-            computeLocationRelativeToParent(v, (View) getParent(), mTargetViewPos);
-            nextState.x = mTargetViewPos[0] - mIndicatorPos[0] - (1 - nextState.scaleX) * indicatorWidth / 2;
-            nextState.y = mTargetViewPos[1] - mIndicatorPos[1] - (1 - nextState.scaleY) * indicatorHeight / 2;
-
-            if (getAlpha() > MIN_VISIBLE_ALPHA) {
-                mTargetState = nextState;
-                mCurrentAnimation = new LauncherViewPropertyAnimator(this)
-                        .alpha(1)
-                        .translationX(mTargetState.x)
-                        .translationY(mTargetState.y)
-                        .scaleX(mTargetState.scaleX)
-                        .scaleY(mTargetState.scaleY);
-            } else {
-                applyState(nextState);
-                mCurrentAnimation = LauncherAnimUtils.ofPropertyValuesHolder(this,
-                        PropertyValuesHolder.ofFloat(View.ALPHA, 1));
-            }
-            mLastFocusedView = v;
-        } else {
-            if (mLastFocusedView == v) {
-                mLastFocusedView = null;
-                endCurrentAnimation();
-                mCurrentAnimation = LauncherAnimUtils.ofPropertyValuesHolder(this,
-                        PropertyValuesHolder.ofFloat(View.ALPHA, 0));
-            }
-        }
-        if (mCurrentAnimation != null) {
-            mCurrentAnimation.setDuration(ANIM_DURATION).start();
-        }
-    }
-
-    private void endCurrentAnimation() {
-        if (mCurrentAnimation != null) {
-            mCurrentAnimation.cancel();
-            mCurrentAnimation = null;
-        }
-        if (mTargetState != null) {
-            applyState(mTargetState);
-            mTargetState = null;
-        }
-    }
-
-    private void applyState(ViewAnimState state) {
-        setTranslationX(state.x);
-        setTranslationY(state.y);
-        setScaleX(state.scaleX);
-        setScaleY(state.scaleY);
-    }
-
-    @Override
-    protected void onDraw(Canvas canvas) {
-        if (mPendingCall != null) {
-            onFocusChange(mPendingCall.first, mPendingCall.second);
-        }
-    }
-
-    /**
-     * Computes the location of a view relative to {@param parent}, off-setting
-     * any shift due to page view scroll.
-     * @param pos an array of two integers in which to hold the coordinates
-     */
-    private static void computeLocationRelativeToParent(View v, View parent, int[] pos) {
-        pos[0] = pos[1] = 0;
-        computeLocationRelativeToParentHelper(v, parent, pos);
-
-        // If a view is scaled, its position will also shift accordingly. For optimization, only
-        // consider this for the last node.
-        pos[0] += (1 - v.getScaleX()) * v.getWidth() / 2;
-        pos[1] += (1 - v.getScaleY()) * v.getHeight() / 2;
-    }
-
-    private static void computeLocationRelativeToParentHelper(View child,
-            View commonParent, int[] shift) {
-        View parent = (View) child.getParent();
-        shift[0] += child.getLeft();
-        shift[1] += child.getTop();
-        if (parent instanceof PagedView) {
-            PagedView page = (PagedView) parent;
-            shift[0] -= page.getScrollForPage(page.indexOfChild(child));
-        }
-
-        if (parent != commonParent) {
-            computeLocationRelativeToParentHelper(parent, commonParent, shift);
-        }
-    }
-
-    @Thunk static final class ViewAnimState {
-        float x, y, scaleX, scaleY;
-    }
-}
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index e1d292cbb..1c94950c6 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -107,6 +107,7 @@ import com.android.launcher3.dragndrop.DragView;
 import com.android.launcher3.dynamicui.ExtractedColors;
 import com.android.launcher3.folder.Folder;
 import com.android.launcher3.folder.FolderIcon;
+import com.android.launcher3.keyboard.ViewGroupFocusHelper;
 import com.android.launcher3.logging.LoggerUtils;
 import com.android.launcher3.logging.UserEventDispatcher;
 import com.android.launcher3.model.WidgetsModel;
@@ -363,7 +364,7 @@ public class Launcher extends Activity
 
     private UserEventDispatcher mUserEventDispatcher;
 
-    public FocusIndicatorView mFocusHandler;
+    public ViewGroupFocusHelper mFocusHandler;
     private boolean mRotationEnabled = false;
 
     @Thunk void setOrientation() {
@@ -1340,8 +1341,9 @@ public class Launcher extends Activity
      */
     private void setupViews() {
         mLauncherView = findViewById(R.id.launcher);
-        mFocusHandler = (FocusIndicatorView) findViewById(R.id.focus_indicator);
         mDragLayer = (DragLayer) findViewById(R.id.drag_layer);
+        mFocusHandler = mDragLayer.getFocusIndicatorHelper();
+
         mWorkspace = (Workspace) mDragLayer.findViewById(R.id.workspace);
         mPageIndicator = (PageIndicatorLine) mDragLayer.findViewById(R.id.page_indicator);
 
diff --git a/src/com/android/launcher3/allapps/AllAppsContainerView.java b/src/com/android/launcher3/allapps/AllAppsContainerView.java
index 95ab286d9..779bd05fc 100644
--- a/src/com/android/launcher3/allapps/AllAppsContainerView.java
+++ b/src/com/android/launcher3/allapps/AllAppsContainerView.java
@@ -52,6 +52,7 @@ import com.android.launcher3.LauncherTransitionable;
 import com.android.launcher3.R;
 import com.android.launcher3.Utilities;
 import com.android.launcher3.Workspace;
+import com.android.launcher3.keyboard.FocusedItemDecorator;
 import com.android.launcher3.util.ComponentKey;
 
 import java.nio.charset.Charset;
@@ -311,6 +312,10 @@ public class AllAppsContainerView extends BaseContainerView implements DragSourc
             mAppsRecyclerView.addItemDecoration(mItemDecoration);
         }
 
+        FocusedItemDecorator focusedItemDecorator = new FocusedItemDecorator(mAppsRecyclerView);
+        mAppsRecyclerView.addItemDecoration(focusedItemDecorator);
+        mAdapter.setIconFocusListener(focusedItemDecorator.getFocusListener());
+
         // Precalculate the prediction icon and normal icon sizes
         LayoutInflater layoutInflater = LayoutInflater.from(getContext());
         final int widthMeasureSpec = MeasureSpec.makeMeasureSpec(
diff --git a/src/com/android/launcher3/allapps/AllAppsGridAdapter.java b/src/com/android/launcher3/allapps/AllAppsGridAdapter.java
index 81a05a23b..4e591bb46 100644
--- a/src/com/android/launcher3/allapps/AllAppsGridAdapter.java
+++ b/src/com/android/launcher3/allapps/AllAppsGridAdapter.java
@@ -33,6 +33,7 @@ import android.support.v7.widget.RecyclerView;
 import android.view.Gravity;
 import android.view.LayoutInflater;
 import android.view.View;
+import android.view.View.OnFocusChangeListener;
 import android.view.ViewConfiguration;
 import android.view.ViewGroup;
 import android.view.accessibility.AccessibilityEvent;
@@ -348,6 +349,7 @@ public class AllAppsGridAdapter extends RecyclerView.Adapter<AllAppsGridAdapter.
 
     private BindViewCallback mBindViewCallback;
     private AllAppsSearchBarController mSearchController;
+    private OnFocusChangeListener mIconFocusListener;
 
     // The text to show when there are no search results and no market search handler.
     private String mEmptySearchMessage;
@@ -412,6 +414,10 @@ public class AllAppsGridAdapter extends RecyclerView.Adapter<AllAppsGridAdapter.
         }
     }
 
+    public void setIconFocusListener(OnFocusChangeListener focusListener) {
+        mIconFocusListener = focusListener;
+    }
+
     /**
      * Sets the last search query that was made, used to show when there are no results and to also
      * seed the intent for searching the market.
@@ -461,26 +467,17 @@ public class AllAppsGridAdapter extends RecyclerView.Adapter<AllAppsGridAdapter.
         switch (viewType) {
             case SECTION_BREAK_VIEW_TYPE:
                 return new ViewHolder(new View(parent.getContext()));
-            case ICON_VIEW_TYPE: {
-                BubbleTextView icon = (BubbleTextView) mLayoutInflater.inflate(
-                        R.layout.all_apps_icon, parent, false);
-                icon.setOnTouchListener(mTouchListener);
-                icon.setOnClickListener(mIconClickListener);
-                icon.setOnLongClickListener(mIconLongClickListener);
-                icon.setLongPressTimeout(ViewConfiguration.get(parent.getContext())
-                        .getLongPressTimeout());
-                icon.setFocusable(true);
-                return new ViewHolder(icon);
-            }
+            case ICON_VIEW_TYPE:
             case PREDICTION_ICON_VIEW_TYPE: {
                 BubbleTextView icon = (BubbleTextView) mLayoutInflater.inflate(
-                        R.layout.all_apps_prediction_bar_icon, parent, false);
+                        viewType == ICON_VIEW_TYPE ? R.layout.all_apps_icon :
+                                R.layout.all_apps_prediction_bar_icon, parent, false);
                 icon.setOnTouchListener(mTouchListener);
                 icon.setOnClickListener(mIconClickListener);
                 icon.setOnLongClickListener(mIconLongClickListener);
                 icon.setLongPressTimeout(ViewConfiguration.get(parent.getContext())
                         .getLongPressTimeout());
-                icon.setFocusable(true);
+                icon.setOnFocusChangeListener(mIconFocusListener);
                 return new ViewHolder(icon);
             }
             case EMPTY_SEARCH_VIEW_TYPE:
diff --git a/src/com/android/launcher3/dragndrop/DragLayer.java b/src/com/android/launcher3/dragndrop/DragLayer.java
index 472da44ac..765ad64e9 100644
--- a/src/com/android/launcher3/dragndrop/DragLayer.java
+++ b/src/com/android/launcher3/dragndrop/DragLayer.java
@@ -61,6 +61,7 @@ import com.android.launcher3.allapps.AllAppsTransitionController;
 import com.android.launcher3.config.FeatureFlags;
 import com.android.launcher3.folder.Folder;
 import com.android.launcher3.folder.FolderIcon;
+import com.android.launcher3.keyboard.ViewGroupFocusHelper;
 import com.android.launcher3.util.Thunk;
 import com.android.launcher3.util.TouchController;
 
@@ -111,6 +112,8 @@ public class DragLayer extends InsettableFrameLayout {
 
     // Related to adjacent page hints
     private final Rect mScrollChildPosition = new Rect();
+    private final ViewGroupFocusHelper mFocusIndicatorHelper;
+
     private boolean mInScrollArea;
     private boolean mShowPageHints;
     private Drawable mLeftHoverDrawable;
@@ -144,6 +147,7 @@ public class DragLayer extends InsettableFrameLayout {
         mLeftHoverDrawableActive = res.getDrawable(R.drawable.page_hover_left_active);
         mRightHoverDrawableActive = res.getDrawable(R.drawable.page_hover_right_active);
         mIsRtl = Utilities.isRtl(res);
+        mFocusIndicatorHelper = new ViewGroupFocusHelper(this);
     }
 
     public void setup(Launcher launcher, DragController dragController,
@@ -157,6 +161,10 @@ public class DragLayer extends InsettableFrameLayout {
         onAccessibilityStateChanged(isAccessibilityEnabled);
     }
 
+    public ViewGroupFocusHelper getFocusIndicatorHelper() {
+        return mFocusIndicatorHelper;
+    }
+
     @Override
     public boolean dispatchKeyEvent(KeyEvent event) {
         return mDragController.dispatchKeyEvent(event) || super.dispatchKeyEvent(event);
@@ -966,6 +974,7 @@ public class DragLayer extends InsettableFrameLayout {
             canvas.restore();
         }
 
+        mFocusIndicatorHelper.draw(canvas);
         super.dispatchDraw(canvas);
     }
 
diff --git a/src/com/android/launcher3/folder/Folder.java b/src/com/android/launcher3/folder/Folder.java
index af9370773..93238de86 100644
--- a/src/com/android/launcher3/folder/Folder.java
+++ b/src/com/android/launcher3/folder/Folder.java
@@ -98,7 +98,7 @@ public class Folder extends LinearLayout implements DragSource, View.OnClickList
     private static final String TAG = "Launcher.Folder";
 
     /**
-     * We avoid measuring {@link #mContentWrapper} with a 0 width or height, as this
+     * We avoid measuring {@link #mContent} with a 0 width or height, as this
      * results in CellLayout being measured as UNSPECIFIED, which it does not support.
      */
     private static final int MIN_CONTENT_DIMEN = 5;
@@ -147,7 +147,6 @@ public class Folder extends LinearLayout implements DragSource, View.OnClickList
     @Thunk FolderIcon mFolderIcon;
 
     @Thunk FolderPagedView mContent;
-    @Thunk View mContentWrapper;
     public ExtendedEditText mFolderName;
     private PageIndicatorDots mPageIndicator;
 
@@ -226,7 +225,6 @@ public class Folder extends LinearLayout implements DragSource, View.OnClickList
     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
-        mContentWrapper = findViewById(R.id.folder_content_wrapper);
         mContent = (FolderPagedView) findViewById(R.id.folder_content);
         mContent.setFolder(this);
 
@@ -562,8 +560,8 @@ public class Folder extends LinearLayout implements DragSource, View.OnClickList
             reveal.setDuration(mMaterialExpandDuration);
             reveal.setInterpolator(new LogDecelerateInterpolator(100, 0));
 
-            mContentWrapper.setAlpha(0f);
-            Animator iconsAlpha = ObjectAnimator.ofFloat(mContentWrapper, "alpha", 0f, 1f);
+            mContent.setAlpha(0f);
+            Animator iconsAlpha = ObjectAnimator.ofFloat(mContent, "alpha", 0f, 1f);
             iconsAlpha.setDuration(mMaterialExpandDuration);
             iconsAlpha.setStartDelay(mMaterialExpandStagger);
             iconsAlpha.setInterpolator(new AccelerateInterpolator(1.5f));
@@ -581,12 +579,12 @@ public class Folder extends LinearLayout implements DragSource, View.OnClickList
 
             openFolderAnim = anim;
 
-            mContentWrapper.setLayerType(LAYER_TYPE_HARDWARE, null);
+            mContent.setLayerType(LAYER_TYPE_HARDWARE, null);
             mFooter.setLayerType(LAYER_TYPE_HARDWARE, null);
             onCompleteRunnable = new Runnable() {
                 @Override
                 public void run() {
-                    mContentWrapper.setLayerType(LAYER_TYPE_NONE, null);
+                    mContent.setLayerType(LAYER_TYPE_NONE, null);
                     mFooter.setLayerType(LAYER_TYPE_NONE, null);
                 }
             };
@@ -1122,7 +1120,7 @@ public class Folder extends LinearLayout implements DragSource, View.OnClickList
         int contentAreaHeightSpec = MeasureSpec.makeMeasureSpec(contentHeight, MeasureSpec.EXACTLY);
 
         mContent.setFixedSize(contentWidth, contentHeight);
-        mContentWrapper.measure(contentAreaWidthSpec, contentAreaHeightSpec);
+        mContent.measure(contentAreaWidthSpec, contentAreaHeightSpec);
 
         if (mContent.getChildCount() > 0) {
             int cellIconGap = (mContent.getPageAt(0).getCellWidth()
diff --git a/src/com/android/launcher3/folder/FolderPagedView.java b/src/com/android/launcher3/folder/FolderPagedView.java
index d8b83ad6c..c56e4e5f9 100644
--- a/src/com/android/launcher3/folder/FolderPagedView.java
+++ b/src/com/android/launcher3/folder/FolderPagedView.java
@@ -18,6 +18,7 @@ package com.android.launcher3.folder;
 
 import android.annotation.SuppressLint;
 import android.content.Context;
+import android.graphics.Canvas;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.Gravity;
@@ -30,7 +31,6 @@ import com.android.launcher3.BubbleTextView;
 import com.android.launcher3.CellLayout;
 import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.FocusHelper.PagedFolderKeyEventListener;
-import com.android.launcher3.FocusIndicatorView;
 import com.android.launcher3.IconCache;
 import com.android.launcher3.InvariantDeviceProfile;
 import com.android.launcher3.ItemInfo;
@@ -45,6 +45,7 @@ import com.android.launcher3.Utilities;
 import com.android.launcher3.Workspace.ItemOperator;
 import com.android.launcher3.dragndrop.DragController;
 import com.android.launcher3.pageindicators.PageIndicator;
+import com.android.launcher3.keyboard.ViewGroupFocusHelper;
 import com.android.launcher3.util.Thunk;
 
 import java.util.ArrayList;
@@ -73,6 +74,7 @@ public class FolderPagedView extends PagedView {
 
     private final LayoutInflater mInflater;
     private final IconCache mIconCache;
+    private final ViewGroupFocusHelper mFocusIndicatorHelper;
 
     @Thunk final HashMap<View, Runnable> mPendingAnimations = new HashMap<>();
 
@@ -90,7 +92,6 @@ public class FolderPagedView extends PagedView {
     private int mGridCountY;
 
     private Folder mFolder;
-    private FocusIndicatorView mFocusIndicatorView;
     private PagedFolderKeyEventListener mKeyListener;
 
     private PageIndicator mPageIndicator;
@@ -112,11 +113,11 @@ public class FolderPagedView extends PagedView {
         setImportantForAccessibility(IMPORTANT_FOR_ACCESSIBILITY_YES);
 
         setEdgeGlowColor(getResources().getColor(R.color.folder_edge_effect_color));
+        mFocusIndicatorHelper = new ViewGroupFocusHelper(this);
     }
 
     public void setFolder(Folder folder) {
         mFolder = folder;
-        mFocusIndicatorView = (FocusIndicatorView) folder.findViewById(R.id.focus_indicator);
         mKeyListener = new PagedFolderKeyEventListener(folder);
         mPageIndicator = (PageIndicator) folder.findViewById(R.id.folder_page_indicator);
     }
@@ -162,6 +163,12 @@ public class FolderPagedView extends PagedView {
         }
     }
 
+    @Override
+    protected void dispatchDraw(Canvas canvas) {
+        mFocusIndicatorHelper.draw(canvas);
+        super.dispatchDraw(canvas);
+    }
+
     /**
      * Binds items to the layout.
      * @return list of items that could not be bound, probably because we hit the max size limit.
@@ -226,7 +233,7 @@ public class FolderPagedView extends PagedView {
         textView.applyFromShortcutInfo(item, mIconCache);
         textView.setOnClickListener(mFolder);
         textView.setOnLongClickListener(mFolder);
-        textView.setOnFocusChangeListener(mFocusIndicatorView);
+        textView.setOnFocusChangeListener(mFocusIndicatorHelper);
         textView.setOnKeyListener(mKeyListener);
 
         textView.setLayoutParams(new CellLayout.LayoutParams(
diff --git a/src/com/android/launcher3/keyboard/FocusIndicatorHelper.java b/src/com/android/launcher3/keyboard/FocusIndicatorHelper.java
new file mode 100644
index 000000000..7672f5a79
--- /dev/null
+++ b/src/com/android/launcher3/keyboard/FocusIndicatorHelper.java
@@ -0,0 +1,242 @@
+/*
+ * 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.launcher3.keyboard;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.ObjectAnimator;
+import android.animation.PropertyValuesHolder;
+import android.animation.RectEvaluator;
+import android.animation.ValueAnimator;
+import android.animation.ValueAnimator.AnimatorUpdateListener;
+import android.annotation.TargetApi;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.graphics.Rect;
+import android.os.Build.VERSION_CODES;
+import android.util.Property;
+import android.view.View;
+import android.view.View.OnFocusChangeListener;
+
+import com.android.launcher3.R;
+
+/**
+ * A helper class to draw background of a focused view.
+ */
+@TargetApi(VERSION_CODES.LOLLIPOP)
+public abstract class FocusIndicatorHelper implements
+        OnFocusChangeListener, AnimatorUpdateListener {
+
+    private static final float MIN_VISIBLE_ALPHA = 0.2f;
+    private static final long ANIM_DURATION = 150;
+
+    public static final Property<FocusIndicatorHelper, Float> ALPHA =
+            new Property<FocusIndicatorHelper, Float>(Float.TYPE, "alpha") {
+                @Override
+                public void set(FocusIndicatorHelper object, Float value) {
+                    object.setAlpha(value);
+                }
+
+                @Override
+                public Float get(FocusIndicatorHelper object) {
+                    return object.mAlpha;
+                }
+            };
+
+    public static final Property<FocusIndicatorHelper, Float> SHIFT =
+            new Property<FocusIndicatorHelper, Float>(
+                    Float.TYPE, "shift") {
+
+                @Override
+                public void set(FocusIndicatorHelper object, Float value) {
+                    object.mShift = value;
+                }
+
+                @Override
+                public Float get(FocusIndicatorHelper object) {
+                    return object.mShift;
+                }
+            };
+
+    private static final RectEvaluator RECT_EVALUATOR = new RectEvaluator(new Rect());
+    private static final Rect sTempRect1 = new Rect();
+    private static final Rect sTempRect2 = new Rect();
+
+    private final View mContainer;
+    private final Paint mPaint;
+    private final int mMaxAlpha;
+
+    private final Rect mDirtyRect = new Rect();
+    private boolean mIsDirty = false;
+
+    private View mLastFocusedView;
+
+    private View mCurrentView;
+    private View mTargetView;
+    /**
+     * The fraction indicating the position of the focusRect between {@link #mCurrentView}
+     * & {@link #mTargetView}
+     */
+    private float mShift;
+
+    private ObjectAnimator mCurrentAnimation;
+    private float mAlpha;
+
+    public FocusIndicatorHelper(View container) {
+        mContainer = container;
+
+        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
+        int color = container.getResources().getColor(R.color.focused_background);
+        mMaxAlpha = Color.alpha(color);
+        mPaint.setColor(0xFF000000 | color);
+
+        setAlpha(0);
+        mShift = 0;
+    }
+
+    protected void setAlpha(float alpha) {
+        mAlpha = alpha;
+        mPaint.setAlpha((int) (mAlpha * mMaxAlpha));
+    }
+
+    @Override
+    public void onAnimationUpdate(ValueAnimator animation) {
+        invalidateDirty();
+    }
+
+    protected void invalidateDirty() {
+        if (mIsDirty) {
+            mContainer.invalidate(mDirtyRect);
+            mIsDirty = false;
+        }
+
+        Rect newRect = getDrawRect();
+        if (newRect != null) {
+            mContainer.invalidate(newRect);
+        }
+    }
+
+    public void draw(Canvas c) {
+        if (mAlpha > 0) {
+            Rect newRect = getDrawRect();
+            if (newRect != null) {
+                mDirtyRect.set(newRect);
+                c.drawRect(mDirtyRect, mPaint);
+                mIsDirty = true;
+            }
+        }
+    }
+
+    private Rect getDrawRect() {
+        if (mCurrentView != null) {
+            viewToRect(mCurrentView, sTempRect1);
+
+            if (mShift > 0 && mTargetView != null) {
+                viewToRect(mTargetView, sTempRect2);
+                return RECT_EVALUATOR.evaluate(mShift, sTempRect1, sTempRect2);
+            } else {
+                return sTempRect1;
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public void onFocusChange(View v, boolean hasFocus) {
+        if (hasFocus) {
+            endCurrentAnimation();
+
+            if (mAlpha > MIN_VISIBLE_ALPHA) {
+                mTargetView = v;
+
+                mCurrentAnimation = ObjectAnimator.ofPropertyValuesHolder(this,
+                        PropertyValuesHolder.ofFloat(ALPHA, 1),
+                        PropertyValuesHolder.ofFloat(SHIFT, 1));
+                mCurrentAnimation.addListener(new ViewSetListener(v, true));
+            } else {
+                setCurrentView(v);
+
+                mCurrentAnimation = ObjectAnimator.ofPropertyValuesHolder(this,
+                        PropertyValuesHolder.ofFloat(ALPHA, 1));
+            }
+
+            mLastFocusedView = v;
+        } else {
+            if (mLastFocusedView == v) {
+                mLastFocusedView = null;
+                endCurrentAnimation();
+                mCurrentAnimation = ObjectAnimator.ofPropertyValuesHolder(this,
+                        PropertyValuesHolder.ofFloat(ALPHA, 0));
+                mCurrentAnimation.addListener(new ViewSetListener(null, false));
+            }
+        }
+
+        // invalidate once
+        invalidateDirty();
+
+        mLastFocusedView = hasFocus ? v : null;
+        if (mCurrentAnimation != null) {
+            mCurrentAnimation.addUpdateListener(this);
+            mCurrentAnimation.setDuration(ANIM_DURATION).start();
+        }
+    }
+
+    protected void endCurrentAnimation() {
+        if (mCurrentAnimation != null) {
+            mCurrentAnimation.cancel();
+            mCurrentAnimation = null;
+        }
+    }
+
+    protected void setCurrentView(View v) {
+        mCurrentView = v;
+        mShift = 0;
+        mTargetView = null;
+    }
+
+    /**
+     * Gets the position of {@param v} relative to {@link #mContainer}.
+     */
+    public abstract void viewToRect(View v, Rect outRect);
+
+    private class ViewSetListener extends AnimatorListenerAdapter {
+        private final View mViewToSet;
+        private final boolean mCallOnCancel;
+        private boolean mCalled = false;
+
+        public ViewSetListener(View v, boolean callOnCancel) {
+            mViewToSet = v;
+            mCallOnCancel = callOnCancel;
+        }
+
+        @Override
+        public void onAnimationCancel(Animator animation) {
+            if (!mCallOnCancel) {
+                mCalled = true;
+            }
+        }
+
+        @Override
+        public void onAnimationEnd(Animator animation) {
+            if (!mCalled) {
+                setCurrentView(mViewToSet);
+                mCalled = true;
+            }
+        }
+    }
+}
diff --git a/src/com/android/launcher3/keyboard/FocusedItemDecorator.java b/src/com/android/launcher3/keyboard/FocusedItemDecorator.java
new file mode 100644
index 000000000..9c80b0f08
--- /dev/null
+++ b/src/com/android/launcher3/keyboard/FocusedItemDecorator.java
@@ -0,0 +1,52 @@
+/*
+ * 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.launcher3.keyboard;
+
+import android.graphics.Canvas;
+import android.graphics.Rect;
+import android.support.v7.widget.RecyclerView;
+import android.support.v7.widget.RecyclerView.ItemDecoration;
+import android.support.v7.widget.RecyclerView.State;
+import android.view.View;
+import android.view.View.OnFocusChangeListener;
+
+/**
+ * {@link ItemDecoration} for drawing and animating focused view background.
+ */
+public class FocusedItemDecorator extends ItemDecoration {
+
+    private FocusIndicatorHelper mHelper;
+
+    public FocusedItemDecorator(View container) {
+        mHelper = new FocusIndicatorHelper(container) {
+
+            @Override
+            public void viewToRect(View v, Rect outRect) {
+                outRect.set(v.getLeft(), v.getTop(), v.getRight(), v.getBottom());
+            }
+        };
+    }
+
+    public OnFocusChangeListener getFocusListener() {
+        return mHelper;
+    }
+
+    @Override
+    public void onDraw(Canvas c, RecyclerView parent, State state) {
+        mHelper.draw(c);
+    }
+}
diff --git a/src/com/android/launcher3/keyboard/ViewGroupFocusHelper.java b/src/com/android/launcher3/keyboard/ViewGroupFocusHelper.java
new file mode 100644
index 000000000..bd5c06e5b
--- /dev/null
+++ b/src/com/android/launcher3/keyboard/ViewGroupFocusHelper.java
@@ -0,0 +1,85 @@
+/*
+ * 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.launcher3.keyboard;
+
+import android.graphics.Rect;
+import android.view.View;
+import android.view.View.OnFocusChangeListener;
+
+import com.android.launcher3.PagedView;
+
+/**
+ * {@link FocusIndicatorHelper} for a generic view group.
+ */
+public class ViewGroupFocusHelper extends FocusIndicatorHelper {
+
+    private final View mContainer;
+
+    public ViewGroupFocusHelper(View container) {
+        super(container);
+        mContainer = container;
+    }
+
+    @Override
+    public void viewToRect(View v, Rect outRect) {
+        outRect.left = 0;
+        outRect.top = 0;
+
+        computeLocationRelativeToContainer(v, outRect);
+
+        // If a view is scaled, its position will also shift accordingly. For optimization, only
+        // consider this for the last node.
+        outRect.left += (1 - v.getScaleX()) * v.getWidth() / 2;
+        outRect.top += (1 - v.getScaleY()) * v.getHeight() / 2;
+
+        outRect.right = outRect.left + (int) (v.getScaleX() * v.getWidth());
+        outRect.bottom = outRect.top + (int) (v.getScaleY() * v.getHeight());
+    }
+
+    private void computeLocationRelativeToContainer(View child, Rect outRect) {
+        View parent = (View) child.getParent();
+        outRect.left += child.getLeft();
+        outRect.top += child.getTop();
+
+        if (parent != mContainer) {
+            if (parent instanceof PagedView) {
+                PagedView page = (PagedView) parent;
+                outRect.left -= page.getScrollForPage(page.indexOfChild(child));
+            }
+
+            computeLocationRelativeToContainer(parent, outRect);
+        }
+    }
+
+    /**
+     * Sets the alpha of this FocusIndicatorHelper to 0 when a view with this listener
+     * receives focus.
+     */
+    public View.OnFocusChangeListener getHideIndicatorOnFocusListener() {
+        return new OnFocusChangeListener() {
+            @Override
+            public void onFocusChange(View v, boolean hasFocus) {
+                if (hasFocus) {
+                    endCurrentAnimation();
+                    setCurrentView(null);
+                    setAlpha(0);
+                    invalidateDirty();
+                }
+            }
+        };
+    }
+}