src/com/android/launcher3/allapps/AllAppsRecyclerView.java - platform/packages/apps/Launcher3 - Git at Google

 /*
  * Copyright (C) 2015 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.allapps;

 import static android.view.View.MeasureSpec.EXACTLY;
 import static android.view.View.MeasureSpec.UNSPECIFIED;
 import static android.view.View.MeasureSpec.makeMeasureSpec;

 import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_VERTICAL_SWIPE_BEGIN;
 import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_VERTICAL_SWIPE_END;
 import static com.android.launcher3.util.LogConfig.SEARCH_LOGGING;
 import static com.android.launcher3.util.UiThreadHelper.hideKeyboardAsync;

 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Canvas;
 import android.graphics.drawable.Drawable;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.util.SparseIntArray;
 import android.view.MotionEvent;
 import android.view.View;

 import androidx.recyclerview.widget.RecyclerView;

 import com.android.launcher3.BaseDraggingActivity;
 import com.android.launcher3.BaseRecyclerView;
 import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.LauncherAppState;
 import com.android.launcher3.R;
 import com.android.launcher3.Utilities;
 import com.android.launcher3.config.FeatureFlags;
 import com.android.launcher3.logging.StatsLogManager;
 import com.android.launcher3.views.ActivityContext;
 import com.android.launcher3.views.RecyclerViewFastScroller;

 import java.util.ArrayList;
 import java.util.List;

 /**
  * A RecyclerView with custom fast scroll support for the all apps view.
  */
 public class AllAppsRecyclerView extends BaseRecyclerView {
     private static final String TAG = "AllAppsContainerView";
     private static final boolean DEBUG = false;
     private static final boolean DEBUG_LATENCY = Utilities.isPropertyEnabled(SEARCH_LOGGING);

     private AlphabeticalAppsList mApps;
     private final int mNumAppsPerRow;

     // The specific view heights that we use to calculate scroll
     private final SparseIntArray mViewHeights = new SparseIntArray();
     private final SparseIntArray mCachedScrollPositions = new SparseIntArray();
     private final AllAppsFastScrollHelper mFastScrollHelper;


     private final AdapterDataObserver mObserver = new RecyclerView.AdapterDataObserver() {
         public void onChanged() {
             mCachedScrollPositions.clear();
         }
     };

     // The empty-search result background
     private AllAppsBackgroundDrawable mEmptySearchBackground;
     private int mEmptySearchBackgroundTopOffset;

     private ArrayList<View> mAutoSizedOverlays = new ArrayList<>();

     public AllAppsRecyclerView(Context context) {
         this(context, null);
     }

     public AllAppsRecyclerView(Context context, AttributeSet attrs) {
         this(context, attrs, 0);
     }

     public AllAppsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
         this(context, attrs, defStyleAttr, 0);
     }

     public AllAppsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr,
             int defStyleRes) {
         super(context, attrs, defStyleAttr);
         Resources res = getResources();
         mEmptySearchBackgroundTopOffset = res.getDimensionPixelSize(
                 R.dimen.all_apps_empty_search_bg_top_offset);
         mNumAppsPerRow = LauncherAppState.getIDP(context).numColumns;
         mFastScrollHelper = new AllAppsFastScrollHelper(this);
     }

     /**
      * Sets the list of apps in this view, used to determine the fastscroll position.
      */
     public void setApps(AlphabeticalAppsList apps) {
         mApps = apps;
     }

     public AlphabeticalAppsList getApps() {
         return mApps;
     }

     private void updatePoolSize() {
         DeviceProfile grid = BaseDraggingActivity.fromContext(getContext()).getDeviceProfile();
         RecyclerView.RecycledViewPool pool = getRecycledViewPool();
         int approxRows = (int) Math.ceil(grid.availableHeightPx / grid.allAppsIconSizePx);
         pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_EMPTY_SEARCH, 1);
         pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_ALL_APPS_DIVIDER, 1);
         pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_SEARCH_MARKET, 1);
         pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_ICON, approxRows
                 * (mNumAppsPerRow + 1));

         mViewHeights.clear();
         mViewHeights.put(AllAppsGridAdapter.VIEW_TYPE_ICON, grid.allAppsCellHeightPx);
     }


     @Override
     public void onDraw(Canvas c) {
         // Draw the background
         if (mEmptySearchBackground != null && mEmptySearchBackground.getAlpha() > 0) {
             mEmptySearchBackground.draw(c);
         }
         if (DEBUG) {
             Log.d(TAG, "onDraw at = " + System.currentTimeMillis());
         }
         if (DEBUG_LATENCY) {
             Log.d(SEARCH_LOGGING,
                     "-- Recycle view onDraw, time stamp = " + System.currentTimeMillis());
         }
         super.onDraw(c);
     }

     @Override
     protected boolean verifyDrawable(Drawable who) {
         return who == mEmptySearchBackground || super.verifyDrawable(who);
     }

     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
         updateEmptySearchBackgroundBounds();
         updatePoolSize();
         for (int i = 0; i < mAutoSizedOverlays.size(); i++) {
             View overlay = mAutoSizedOverlays.get(i);
             overlay.measure(makeMeasureSpec(w, EXACTLY), makeMeasureSpec(w, EXACTLY));
             overlay.layout(0, 0, w, h);
         }
     }

     /**
      * Adds an overlay that automatically rescales with the recyclerview.
      */
     public void addAutoSizedOverlay(View overlay) {
         mAutoSizedOverlays.add(overlay);
         getOverlay().add(overlay);
         onSizeChanged(getWidth(), getHeight(), getWidth(), getHeight());
     }

     /**
      * Clears auto scaling overlay views added by #addAutoSizedOverlay
      */
     public void clearAutoSizedOverlays() {
         for (View v : mAutoSizedOverlays) {
             getOverlay().remove(v);
         }
         mAutoSizedOverlays.clear();
     }

     public void onSearchResultsChanged() {
         // Always scroll the view to the top so the user can see the changed results
         scrollToTop();

         if (mApps.hasNoFilteredResults() && !FeatureFlags.ENABLE_DEVICE_SEARCH.get()) {
             if (mEmptySearchBackground == null) {
                 mEmptySearchBackground = new AllAppsBackgroundDrawable(getContext());
                 mEmptySearchBackground.setAlpha(0);
                 mEmptySearchBackground.setCallback(this);
                 updateEmptySearchBackgroundBounds();
             }
             mEmptySearchBackground.animateBgAlpha(1f, 150);
         } else if (mEmptySearchBackground != null) {
             // For the time being, we just immediately hide the background to ensure that it does
             // not overlap with the results
             mEmptySearchBackground.setBgAlpha(0f);
         }
     }

     @Override
     public void onScrollStateChanged(int state) {
         super.onScrollStateChanged(state);

         StatsLogManager mgr = BaseDraggingActivity.fromContext(getContext()).getStatsLogManager();
         switch (state) {
             case SCROLL_STATE_DRAGGING:
                 requestFocus();
                 mgr.logger().sendToInteractionJankMonitor(
                         LAUNCHER_ALLAPPS_VERTICAL_SWIPE_BEGIN, this);
                 break;
             case SCROLL_STATE_IDLE:
                 mgr.logger().sendToInteractionJankMonitor(
                         LAUNCHER_ALLAPPS_VERTICAL_SWIPE_END, this);
                 break;
         }
     }

     @Override
     public boolean onInterceptTouchEvent(MotionEvent e) {
         boolean result = super.onInterceptTouchEvent(e);
         if (!result && e.getAction() == MotionEvent.ACTION_DOWN
                 && mEmptySearchBackground != null && mEmptySearchBackground.getAlpha() > 0) {
             mEmptySearchBackground.setHotspot(e.getX(), e.getY());
         }
         hideKeyboardAsync(ActivityContext.lookupContext(getContext()),
                 getApplicationWindowToken());
         return result;
     }

     /**
      * Maps the touch (from 0..1) to the adapter position that should be visible.
      */
     @Override
     public String scrollToPositionAtProgress(float touchFraction) {
         int rowCount = mApps.getNumAppRows();
         if (rowCount == 0) {
             return "";
         }

         // Find the fastscroll section that maps to this touch fraction
         List<AlphabeticalAppsList.FastScrollSectionInfo> fastScrollSections =
                 mApps.getFastScrollerSections();
         AlphabeticalAppsList.FastScrollSectionInfo lastInfo = fastScrollSections.get(0);
         for (int i = 1; i < fastScrollSections.size(); i++) {
             AlphabeticalAppsList.FastScrollSectionInfo info = fastScrollSections.get(i);
             if (info.touchFraction > touchFraction) {
                 break;
             }
             lastInfo = info;
         }

         mFastScrollHelper.smoothScrollToSection(lastInfo);
         return lastInfo.sectionName;
     }

     @Override
     public void onFastScrollCompleted() {
         super.onFastScrollCompleted();
         mFastScrollHelper.onFastScrollCompleted();
     }

     @Override
     public void setAdapter(Adapter adapter) {
         if (getAdapter() != null) {
             getAdapter().unregisterAdapterDataObserver(mObserver);
         }
         super.setAdapter(adapter);
         if (adapter != null) {
             adapter.registerAdapterDataObserver(mObserver);
         }
     }

     @Override
     protected float getBottomFadingEdgeStrength() {
         // No bottom fading edge.
         return 0;
     }

     @Override
     protected boolean isPaddingOffsetRequired() {
         return true;
     }

     @Override
     protected int getTopPaddingOffset() {
         return -getPaddingTop();
     }

     /**
      * Updates the bounds for the scrollbar.
      */
     @Override
     public void onUpdateScrollbar(int dy) {
         if (mApps == null) {
             return;
         }
         List<AllAppsGridAdapter.AdapterItem> items = mApps.getAdapterItems();

         // Skip early if there are no items or we haven't been measured
         if (items.isEmpty() || mNumAppsPerRow == 0) {
             mScrollbar.setThumbOffsetY(-1);
             return;
         }

         // Skip early if, there no child laid out in the container.
         int scrollY = getCurrentScrollY();
         if (scrollY < 0) {
             mScrollbar.setThumbOffsetY(-1);
             return;
         }

         // Only show the scrollbar if there is height to be scrolled
         int availableScrollBarHeight = getAvailableScrollBarHeight();
         int availableScrollHeight = getAvailableScrollHeight();
         if (availableScrollHeight <= 0) {
             mScrollbar.setThumbOffsetY(-1);
             return;
         }

         if (mScrollbar.isThumbDetached()) {
             if (!mScrollbar.isDraggingThumb()) {
                 // Calculate the current scroll position, the scrollY of the recycler view accounts
                 // for the view padding, while the scrollBarY is drawn right up to the background
                 // padding (ignoring padding)
                 int scrollBarY = (int)
                         (((float) scrollY / availableScrollHeight) * availableScrollBarHeight);

                 int thumbScrollY = mScrollbar.getThumbOffsetY();
                 int diffScrollY = scrollBarY - thumbScrollY;
                 if (diffScrollY * dy > 0f) {
                     // User is scrolling in the same direction the thumb needs to catch up to the
                     // current scroll position.  We do this by mapping the difference in movement
                     // from the original scroll bar position to the difference in movement necessary
                     // in the detached thumb position to ensure that both speed towards the same
                     // position at either end of the list.
                     if (dy < 0) {
                         int offset = (int) ((dy * thumbScrollY) / (float) scrollBarY);
                         thumbScrollY += Math.max(offset, diffScrollY);
                     } else {
                         int offset = (int) ((dy * (availableScrollBarHeight - thumbScrollY)) /
                                 (float) (availableScrollBarHeight - scrollBarY));
                         thumbScrollY += Math.min(offset, diffScrollY);
                     }
                     thumbScrollY = Math.max(0, Math.min(availableScrollBarHeight, thumbScrollY));
                     mScrollbar.setThumbOffsetY(thumbScrollY);
                     if (scrollBarY == thumbScrollY) {
                         mScrollbar.reattachThumbToScroll();
                     }
                 } else {
                     // User is scrolling in an opposite direction to the direction that the thumb
                     // needs to catch up to the scroll position.  Do nothing except for updating
                     // the scroll bar x to match the thumb width.
                     mScrollbar.setThumbOffsetY(thumbScrollY);
                 }
             }
         } else {
             synchronizeScrollBarThumbOffsetToViewScroll(scrollY, availableScrollHeight);
         }
     }

     @Override
     public boolean supportsFastScrolling() {
         // Only allow fast scrolling when the user is not searching, since the results are not
         // grouped in a meaningful order
         return !mApps.hasFilter();
     }

     @Override
     public int getCurrentScrollY() {
         // Return early if there are no items or we haven't been measured
         List<AllAppsGridAdapter.AdapterItem> items = mApps.getAdapterItems();
         if (items.isEmpty() || mNumAppsPerRow == 0 || getChildCount() == 0) {
             return -1;
         }

         // Calculate the y and offset for the item
         View child = getChildAt(0);
         int position = getChildPosition(child);
         if (position == NO_POSITION) {
             return -1;
         }
         return getPaddingTop() +
                 getCurrentScrollY(position, getLayoutManager().getDecoratedTop(child));
     }

     public int getCurrentScrollY(int position, int offset) {
         List<AllAppsGridAdapter.AdapterItem> items = mApps.getAdapterItems();
         AllAppsGridAdapter.AdapterItem posItem = position < items.size()
                 ? items.get(position) : null;
         int y = mCachedScrollPositions.get(position, -1);
         if (y < 0) {
             y = 0;
             for (int i = 0; i < position; i++) {
                 AllAppsGridAdapter.AdapterItem item = items.get(i);
                 if (AllAppsGridAdapter.isIconViewType(item.viewType)) {
                     // Break once we reach the desired row
                     if (posItem != null && posItem.viewType == item.viewType &&
                             posItem.rowIndex == item.rowIndex) {
                         break;
                     }
                     // Otherwise, only account for the first icon in the row since they are the same
                     // size within a row
                     if (item.rowAppIndex == 0) {
                         y += mViewHeights.get(item.viewType, 0);
                     }
                 } else {
                     // Rest of the views span the full width
                     int elHeight = mViewHeights.get(item.viewType);
                     if (elHeight == 0) {
                         ViewHolder holder = findViewHolderForAdapterPosition(i);
                         if (holder == null) {
                             holder = getAdapter().createViewHolder(this, item.viewType);
                             getAdapter().onBindViewHolder(holder, i);
                             holder.itemView.measure(UNSPECIFIED, UNSPECIFIED);
                             elHeight = holder.itemView.getMeasuredHeight();

                             getRecycledViewPool().putRecycledView(holder);
                         } else {
                             elHeight = holder.itemView.getMeasuredHeight();
                         }
                     }
                     y += elHeight;
                 }
             }
             mCachedScrollPositions.put(position, y);
         }
         return y - offset;
     }

     /**
      * Returns the available scroll height:
      * AvailableScrollHeight = Total height of the all items - last page height
      */
     @Override
     protected int getAvailableScrollHeight() {
         return getPaddingTop() + getCurrentScrollY(getAdapter().getItemCount(), 0)
                 - getHeight() + getPaddingBottom();
     }

     public int getScrollBarTop() {
         return getResources().getDimensionPixelOffset(R.dimen.all_apps_header_top_padding);
     }

     public RecyclerViewFastScroller getScrollbar() {
         return mScrollbar;
     }

     /**
      * Updates the bounds of the empty search background.
      */
     private void updateEmptySearchBackgroundBounds() {
         if (mEmptySearchBackground == null) {
             return;
         }

         // Center the empty search background on this new view bounds
         int x = (getMeasuredWidth() - mEmptySearchBackground.getIntrinsicWidth()) / 2;
         int y = mEmptySearchBackgroundTopOffset;
         mEmptySearchBackground.setBounds(x, y,
                 x + mEmptySearchBackground.getIntrinsicWidth(),
                 y + mEmptySearchBackground.getIntrinsicHeight());
     }

     @Override
     public boolean hasOverlappingRendering() {
         return false;
     }

     /**
      * Returns distance between left and right app icons
      */
     public int getTabWidth() {
         DeviceProfile grid = BaseDraggingActivity.fromContext(getContext()).getDeviceProfile();
         int totalWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight();
         int iconPadding = totalWidth / grid.numShownAllAppsColumns - grid.allAppsIconSizePx;
         return totalWidth - iconPadding - grid.allAppsIconDrawablePaddingPx;
     }
 }
	/*
	* Copyright (C) 2015 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.allapps;

	import static android.view.View.MeasureSpec.EXACTLY;
	import static android.view.View.MeasureSpec.UNSPECIFIED;
	import static android.view.View.MeasureSpec.makeMeasureSpec;

	import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_VERTICAL_SWIPE_BEGIN;
	import static com.android.launcher3.logging.StatsLogManager.LauncherEvent.LAUNCHER_ALLAPPS_VERTICAL_SWIPE_END;
	import static com.android.launcher3.util.LogConfig.SEARCH_LOGGING;
	import static com.android.launcher3.util.UiThreadHelper.hideKeyboardAsync;

	import android.content.Context;
	import android.content.res.Resources;
	import android.graphics.Canvas;
	import android.graphics.drawable.Drawable;
	import android.util.AttributeSet;
	import android.util.Log;
	import android.util.SparseIntArray;
	import android.view.MotionEvent;
	import android.view.View;

	import androidx.recyclerview.widget.RecyclerView;

	import com.android.launcher3.BaseDraggingActivity;
	import com.android.launcher3.BaseRecyclerView;
	import com.android.launcher3.DeviceProfile;
	import com.android.launcher3.LauncherAppState;
	import com.android.launcher3.R;
	import com.android.launcher3.Utilities;
	import com.android.launcher3.config.FeatureFlags;
	import com.android.launcher3.logging.StatsLogManager;
	import com.android.launcher3.views.ActivityContext;
	import com.android.launcher3.views.RecyclerViewFastScroller;

	import java.util.ArrayList;
	import java.util.List;

	/**
	* A RecyclerView with custom fast scroll support for the all apps view.
	*/
	public class AllAppsRecyclerView extends BaseRecyclerView {
	private static final String TAG = "AllAppsContainerView";
	private static final boolean DEBUG = false;
	private static final boolean DEBUG_LATENCY = Utilities.isPropertyEnabled(SEARCH_LOGGING);

	private AlphabeticalAppsList mApps;
	private final int mNumAppsPerRow;

	// The specific view heights that we use to calculate scroll
	private final SparseIntArray mViewHeights = new SparseIntArray();
	private final SparseIntArray mCachedScrollPositions = new SparseIntArray();
	private final AllAppsFastScrollHelper mFastScrollHelper;


	private final AdapterDataObserver mObserver = new RecyclerView.AdapterDataObserver() {
	public void onChanged() {
	mCachedScrollPositions.clear();
	}
	};

	// The empty-search result background
	private AllAppsBackgroundDrawable mEmptySearchBackground;
	private int mEmptySearchBackgroundTopOffset;

	private ArrayList<View> mAutoSizedOverlays = new ArrayList<>();

	public AllAppsRecyclerView(Context context) {
	this(context, null);
	}

	public AllAppsRecyclerView(Context context, AttributeSet attrs) {
	this(context, attrs, 0);
	}

	public AllAppsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr) {
	this(context, attrs, defStyleAttr, 0);
	}

	public AllAppsRecyclerView(Context context, AttributeSet attrs, int defStyleAttr,
	int defStyleRes) {
	super(context, attrs, defStyleAttr);
	Resources res = getResources();
	mEmptySearchBackgroundTopOffset = res.getDimensionPixelSize(
	R.dimen.all_apps_empty_search_bg_top_offset);
	mNumAppsPerRow = LauncherAppState.getIDP(context).numColumns;
	mFastScrollHelper = new AllAppsFastScrollHelper(this);
	}

	/**
	* Sets the list of apps in this view, used to determine the fastscroll position.
	*/
	public void setApps(AlphabeticalAppsList apps) {
	mApps = apps;
	}

	public AlphabeticalAppsList getApps() {
	return mApps;
	}

	private void updatePoolSize() {
	DeviceProfile grid = BaseDraggingActivity.fromContext(getContext()).getDeviceProfile();
	RecyclerView.RecycledViewPool pool = getRecycledViewPool();
	int approxRows = (int) Math.ceil(grid.availableHeightPx / grid.allAppsIconSizePx);
	pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_EMPTY_SEARCH, 1);
	pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_ALL_APPS_DIVIDER, 1);
	pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_SEARCH_MARKET, 1);
	pool.setMaxRecycledViews(AllAppsGridAdapter.VIEW_TYPE_ICON, approxRows
	* (mNumAppsPerRow + 1));

	mViewHeights.clear();
	mViewHeights.put(AllAppsGridAdapter.VIEW_TYPE_ICON, grid.allAppsCellHeightPx);
	}


	@Override
	public void onDraw(Canvas c) {
	// Draw the background
	if (mEmptySearchBackground != null && mEmptySearchBackground.getAlpha() > 0) {
	mEmptySearchBackground.draw(c);
	}
	if (DEBUG) {
	Log.d(TAG, "onDraw at = " + System.currentTimeMillis());
	}
	if (DEBUG_LATENCY) {
	Log.d(SEARCH_LOGGING,
	"-- Recycle view onDraw, time stamp = " + System.currentTimeMillis());
	}
	super.onDraw(c);
	}

	@Override
	protected boolean verifyDrawable(Drawable who) {
	return who == mEmptySearchBackground \|\| super.verifyDrawable(who);
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
	updateEmptySearchBackgroundBounds();
	updatePoolSize();
	for (int i = 0; i < mAutoSizedOverlays.size(); i++) {
	View overlay = mAutoSizedOverlays.get(i);
	overlay.measure(makeMeasureSpec(w, EXACTLY), makeMeasureSpec(w, EXACTLY));
	overlay.layout(0, 0, w, h);
	}
	}

	/**
	* Adds an overlay that automatically rescales with the recyclerview.
	*/
	public void addAutoSizedOverlay(View overlay) {
	mAutoSizedOverlays.add(overlay);
	getOverlay().add(overlay);
	onSizeChanged(getWidth(), getHeight(), getWidth(), getHeight());
	}

	/**
	* Clears auto scaling overlay views added by #addAutoSizedOverlay
	*/
	public void clearAutoSizedOverlays() {
	for (View v : mAutoSizedOverlays) {
	getOverlay().remove(v);
	}
	mAutoSizedOverlays.clear();
	}

	public void onSearchResultsChanged() {
	// Always scroll the view to the top so the user can see the changed results
	scrollToTop();

	if (mApps.hasNoFilteredResults() && !FeatureFlags.ENABLE_DEVICE_SEARCH.get()) {
	if (mEmptySearchBackground == null) {
	mEmptySearchBackground = new AllAppsBackgroundDrawable(getContext());
	mEmptySearchBackground.setAlpha(0);
	mEmptySearchBackground.setCallback(this);
	updateEmptySearchBackgroundBounds();
	}
	mEmptySearchBackground.animateBgAlpha(1f, 150);
	} else if (mEmptySearchBackground != null) {
	// For the time being, we just immediately hide the background to ensure that it does
	// not overlap with the results
	mEmptySearchBackground.setBgAlpha(0f);
	}
	}

	@Override
	public void onScrollStateChanged(int state) {
	super.onScrollStateChanged(state);

	StatsLogManager mgr = BaseDraggingActivity.fromContext(getContext()).getStatsLogManager();
	switch (state) {
	case SCROLL_STATE_DRAGGING:
	requestFocus();
	mgr.logger().sendToInteractionJankMonitor(
	LAUNCHER_ALLAPPS_VERTICAL_SWIPE_BEGIN, this);
	break;
	case SCROLL_STATE_IDLE:
	mgr.logger().sendToInteractionJankMonitor(
	LAUNCHER_ALLAPPS_VERTICAL_SWIPE_END, this);
	break;
	}
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent e) {
	boolean result = super.onInterceptTouchEvent(e);
	if (!result && e.getAction() == MotionEvent.ACTION_DOWN
	&& mEmptySearchBackground != null && mEmptySearchBackground.getAlpha() > 0) {
	mEmptySearchBackground.setHotspot(e.getX(), e.getY());
	}
	hideKeyboardAsync(ActivityContext.lookupContext(getContext()),
	getApplicationWindowToken());
	return result;
	}

	/**
	* Maps the touch (from 0..1) to the adapter position that should be visible.
	*/
	@Override
	public String scrollToPositionAtProgress(float touchFraction) {
	int rowCount = mApps.getNumAppRows();
	if (rowCount == 0) {
	return "";
	}

	// Find the fastscroll section that maps to this touch fraction
	List<AlphabeticalAppsList.FastScrollSectionInfo> fastScrollSections =
	mApps.getFastScrollerSections();
	AlphabeticalAppsList.FastScrollSectionInfo lastInfo = fastScrollSections.get(0);
	for (int i = 1; i < fastScrollSections.size(); i++) {
	AlphabeticalAppsList.FastScrollSectionInfo info = fastScrollSections.get(i);
	if (info.touchFraction > touchFraction) {
	break;
	}
	lastInfo = info;
	}

	mFastScrollHelper.smoothScrollToSection(lastInfo);
	return lastInfo.sectionName;
	}

	@Override
	public void onFastScrollCompleted() {
	super.onFastScrollCompleted();
	mFastScrollHelper.onFastScrollCompleted();
	}

	@Override
	public void setAdapter(Adapter adapter) {
	if (getAdapter() != null) {
	getAdapter().unregisterAdapterDataObserver(mObserver);
	}
	super.setAdapter(adapter);
	if (adapter != null) {
	adapter.registerAdapterDataObserver(mObserver);
	}
	}

	@Override
	protected float getBottomFadingEdgeStrength() {
	// No bottom fading edge.
	return 0;
	}

	@Override
	protected boolean isPaddingOffsetRequired() {
	return true;
	}

	@Override
	protected int getTopPaddingOffset() {
	return -getPaddingTop();
	}

	/**
	* Updates the bounds for the scrollbar.
	*/
	@Override
	public void onUpdateScrollbar(int dy) {
	if (mApps == null) {
	return;
	}
	List<AllAppsGridAdapter.AdapterItem> items = mApps.getAdapterItems();

	// Skip early if there are no items or we haven't been measured
	if (items.isEmpty() \|\| mNumAppsPerRow == 0) {
	mScrollbar.setThumbOffsetY(-1);
	return;
	}

	// Skip early if, there no child laid out in the container.
	int scrollY = getCurrentScrollY();
	if (scrollY < 0) {
	mScrollbar.setThumbOffsetY(-1);
	return;
	}

	// Only show the scrollbar if there is height to be scrolled
	int availableScrollBarHeight = getAvailableScrollBarHeight();
	int availableScrollHeight = getAvailableScrollHeight();
	if (availableScrollHeight <= 0) {
	mScrollbar.setThumbOffsetY(-1);
	return;
	}

	if (mScrollbar.isThumbDetached()) {
	if (!mScrollbar.isDraggingThumb()) {
	// Calculate the current scroll position, the scrollY of the recycler view accounts
	// for the view padding, while the scrollBarY is drawn right up to the background
	// padding (ignoring padding)
	int scrollBarY = (int)
	(((float) scrollY / availableScrollHeight) * availableScrollBarHeight);

	int thumbScrollY = mScrollbar.getThumbOffsetY();
	int diffScrollY = scrollBarY - thumbScrollY;
	if (diffScrollY * dy > 0f) {
	// User is scrolling in the same direction the thumb needs to catch up to the
	// current scroll position. We do this by mapping the difference in movement
	// from the original scroll bar position to the difference in movement necessary
	// in the detached thumb position to ensure that both speed towards the same
	// position at either end of the list.
	if (dy < 0) {
	int offset = (int) ((dy * thumbScrollY) / (float) scrollBarY);
	thumbScrollY += Math.max(offset, diffScrollY);
	} else {
	int offset = (int) ((dy * (availableScrollBarHeight - thumbScrollY)) /
	(float) (availableScrollBarHeight - scrollBarY));
	thumbScrollY += Math.min(offset, diffScrollY);
	}
	thumbScrollY = Math.max(0, Math.min(availableScrollBarHeight, thumbScrollY));
	mScrollbar.setThumbOffsetY(thumbScrollY);
	if (scrollBarY == thumbScrollY) {
	mScrollbar.reattachThumbToScroll();
	}
	} else {
	// User is scrolling in an opposite direction to the direction that the thumb
	// needs to catch up to the scroll position. Do nothing except for updating
	// the scroll bar x to match the thumb width.
	mScrollbar.setThumbOffsetY(thumbScrollY);
	}
	}
	} else {
	synchronizeScrollBarThumbOffsetToViewScroll(scrollY, availableScrollHeight);
	}
	}

	@Override
	public boolean supportsFastScrolling() {
	// Only allow fast scrolling when the user is not searching, since the results are not
	// grouped in a meaningful order
	return !mApps.hasFilter();
	}

	@Override
	public int getCurrentScrollY() {
	// Return early if there are no items or we haven't been measured
	List<AllAppsGridAdapter.AdapterItem> items = mApps.getAdapterItems();
	if (items.isEmpty() \|\| mNumAppsPerRow == 0 \|\| getChildCount() == 0) {
	return -1;
	}

	// Calculate the y and offset for the item
	View child = getChildAt(0);
	int position = getChildPosition(child);
	if (position == NO_POSITION) {
	return -1;
	}
	return getPaddingTop() +
	getCurrentScrollY(position, getLayoutManager().getDecoratedTop(child));
	}

	public int getCurrentScrollY(int position, int offset) {
	List<AllAppsGridAdapter.AdapterItem> items = mApps.getAdapterItems();
	AllAppsGridAdapter.AdapterItem posItem = position < items.size()
	? items.get(position) : null;
	int y = mCachedScrollPositions.get(position, -1);
	if (y < 0) {
	y = 0;
	for (int i = 0; i < position; i++) {
	AllAppsGridAdapter.AdapterItem item = items.get(i);
	if (AllAppsGridAdapter.isIconViewType(item.viewType)) {
	// Break once we reach the desired row
	if (posItem != null && posItem.viewType == item.viewType &&
	posItem.rowIndex == item.rowIndex) {
	break;
	}
	// Otherwise, only account for the first icon in the row since they are the same
	// size within a row
	if (item.rowAppIndex == 0) {
	y += mViewHeights.get(item.viewType, 0);
	}
	} else {
	// Rest of the views span the full width
	int elHeight = mViewHeights.get(item.viewType);
	if (elHeight == 0) {
	ViewHolder holder = findViewHolderForAdapterPosition(i);
	if (holder == null) {
	holder = getAdapter().createViewHolder(this, item.viewType);
	getAdapter().onBindViewHolder(holder, i);
	holder.itemView.measure(UNSPECIFIED, UNSPECIFIED);
	elHeight = holder.itemView.getMeasuredHeight();

	getRecycledViewPool().putRecycledView(holder);
	} else {
	elHeight = holder.itemView.getMeasuredHeight();
	}
	}
	y += elHeight;
	}
	}
	mCachedScrollPositions.put(position, y);
	}
	return y - offset;
	}

	/**
	* Returns the available scroll height:
	* AvailableScrollHeight = Total height of the all items - last page height
	*/
	@Override
	protected int getAvailableScrollHeight() {
	return getPaddingTop() + getCurrentScrollY(getAdapter().getItemCount(), 0)
	- getHeight() + getPaddingBottom();
	}

	public int getScrollBarTop() {
	return getResources().getDimensionPixelOffset(R.dimen.all_apps_header_top_padding);
	}

	public RecyclerViewFastScroller getScrollbar() {
	return mScrollbar;
	}

	/**
	* Updates the bounds of the empty search background.
	*/
	private void updateEmptySearchBackgroundBounds() {
	if (mEmptySearchBackground == null) {
	return;
	}

	// Center the empty search background on this new view bounds
	int x = (getMeasuredWidth() - mEmptySearchBackground.getIntrinsicWidth()) / 2;
	int y = mEmptySearchBackgroundTopOffset;
	mEmptySearchBackground.setBounds(x, y,
	x + mEmptySearchBackground.getIntrinsicWidth(),
	y + mEmptySearchBackground.getIntrinsicHeight());
	}

	@Override
	public boolean hasOverlappingRendering() {
	return false;
	}

	/**
	* Returns distance between left and right app icons
	*/
	public int getTabWidth() {
	DeviceProfile grid = BaseDraggingActivity.fromContext(getContext()).getDeviceProfile();
	int totalWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight();
	int iconPadding = totalWidth / grid.numShownAllAppsColumns - grid.allAppsIconSizePx;
	return totalWidth - iconPadding - grid.allAppsIconDrawablePaddingPx;
	}
	}