src/com/android/launcher3/widget/picker/SearchAndRecommendationsScrollController.java - platform/packages/apps/Launcher3 - Git at Google

 /*
  * Copyright (C) 2021 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.picker;

 import android.animation.ValueAnimator;
 import android.graphics.Point;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup.MarginLayoutParams;
 import android.widget.RelativeLayout;
 import android.widget.TextView;

 import androidx.annotation.Nullable;

 import com.android.launcher3.views.RecyclerViewFastScroller;
 import com.android.launcher3.widget.picker.WidgetsFullSheet.SearchAndRecommendationViewHolder;
 import com.android.launcher3.workprofile.PersonalWorkPagedView;

 /**
  * A controller which measures & updates {@link WidgetsFullSheet}'s views padding, margin and
  * vertical displacement upon scrolling.
  */
 final class SearchAndRecommendationsScrollController implements
         RecyclerViewFastScroller.OnFastScrollChangeListener, ValueAnimator.AnimatorUpdateListener {
     private final boolean mHasWorkProfile;
     private final SearchAndRecommendationViewHolder mViewHolder;
     private final View mSearchAndRecommendationViewParent;
     private final WidgetsRecyclerView mPrimaryRecyclerView;
     private final WidgetsRecyclerView mSearchRecyclerView;
     private final TextView mNoWidgetsView;
     private final int mTabsHeight;
     private final ValueAnimator mAnimator = ValueAnimator.ofInt(0, 0);
     private final Point mTempOffset = new Point();
     private int mBottomInset;

     // The following are only non null if mHasWorkProfile is true.
     @Nullable private final WidgetsRecyclerView mWorkRecyclerView;
     @Nullable private final View mPrimaryWorkTabsView;
     @Nullable private final PersonalWorkPagedView mPrimaryWorkViewPager;

     private WidgetsRecyclerView mCurrentRecyclerView;
     private int mCurrentRecyclerViewScrollY = 0;

     private OnContentChangeListener mOnContentChangeListener = () -> onScrollChanged();

     /**
      * The vertical distance, in pixels, until the search is pinned at the top of the screen when
      * the user scrolls down the recycler view.
      */
     private int mCollapsibleHeightForSearch = 0;
     /**
      * The vertical distance, in pixels, until the recommendation table disappears from the top of
      * the screen when the user scrolls down the recycler view.
      */
     private int mCollapsibleHeightForRecommendation = 0;
     /**
      * The vertical distance, in pixels, until the tabs is pinned at the top of the screen when the
      * user scrolls down the recycler view.
      *
      * <p>Always 0 if there is no work profile.
      */
     private int mCollapsibleHeightForTabs = 0;

     private boolean mShouldForwardToRecyclerView = false;

     SearchAndRecommendationsScrollController(
             boolean hasWorkProfile,
             int tabsHeight,
             SearchAndRecommendationViewHolder viewHolder,
             WidgetsRecyclerView primaryRecyclerView,
             @Nullable WidgetsRecyclerView workRecyclerView,
             WidgetsRecyclerView searchRecyclerView,
             @Nullable View personalWorkTabsView,
             @Nullable PersonalWorkPagedView primaryWorkViewPager,
             TextView noWidgetsView) {
         mHasWorkProfile = hasWorkProfile;
         mViewHolder = viewHolder;
         mViewHolder.mContainer.setSearchAndRecommendationScrollController(this);
         mSearchAndRecommendationViewParent = (View) mViewHolder.mContainer.getParent();
         mPrimaryRecyclerView = primaryRecyclerView;
         mWorkRecyclerView = workRecyclerView;
         mSearchRecyclerView = searchRecyclerView;
         mPrimaryWorkTabsView = personalWorkTabsView;
         mPrimaryWorkViewPager = primaryWorkViewPager;
         mTabsHeight = tabsHeight;
         mNoWidgetsView = noWidgetsView;
         setCurrentRecyclerView(mPrimaryRecyclerView, /* animateReset= */ false);
     }

     public void setCurrentRecyclerView(WidgetsRecyclerView currentRecyclerView) {
         setCurrentRecyclerView(currentRecyclerView, /* animateReset= */ true);
     }

     /** Sets the current active {@link WidgetsRecyclerView}. */
     private void setCurrentRecyclerView(WidgetsRecyclerView currentRecyclerView,
             boolean animateReset) {
         if (mCurrentRecyclerView == currentRecyclerView) {
             return;
         }
         if (mCurrentRecyclerView != null) {
             mCurrentRecyclerView.setOnContentChangeListener(null);
         }
         mCurrentRecyclerView = currentRecyclerView;
         mCurrentRecyclerView.setOnContentChangeListener(mOnContentChangeListener);
         reset(animateReset);
     }

     /**
      * Updates padding of {@link WidgetsFullSheet} contents to include {@code bottomInset} wherever
      * necessary.
      */
     public boolean updateBottomInset(int bottomInset) {
         mBottomInset = bottomInset;
         return updateMarginAndPadding();
     }

     /**
      * Updates the margin and padding of {@link WidgetsFullSheet} to accumulate collapsible views.
      *
      * @return {@code true} if margins or/and padding of views in the search and recommendations
      * container have been updated.
      */
     public boolean updateMarginAndPadding() {
         boolean hasMarginOrPaddingUpdated = false;
         mCollapsibleHeightForSearch = measureHeightWithVerticalMargins(mViewHolder.mHeaderTitle);
         mCollapsibleHeightForRecommendation =
                 measureHeightWithVerticalMargins(mViewHolder.mHeaderTitle)
                         + measureHeightWithVerticalMargins(mViewHolder.mCollapseHandle)
                         + measureHeightWithVerticalMargins((View) mViewHolder.mSearchBarContainer)
                         + measureHeightWithVerticalMargins(mViewHolder.mRecommendedWidgetsTable);

         int topContainerHeight = measureHeightWithVerticalMargins(mViewHolder.mContainer);
         int noWidgetsViewHeight =  topContainerHeight - mBottomInset;

         if (mHasWorkProfile) {
             mCollapsibleHeightForTabs = measureHeightWithVerticalMargins(mViewHolder.mHeaderTitle)
                     + measureHeightWithVerticalMargins(mViewHolder.mRecommendedWidgetsTable);
             // In a work profile setup, the full widget sheet contains the following views:
             //           ------- (pinned)           -|
             //          Widgets (collapsible)       -|---> LinearLayout for search & recommendations
             //          Search bar (pinned)         -|
             //  Widgets recommendation (collapsible)-|
             //      Personal | Work (pinned)
             //           View Pager
             //
             // Views after the search & recommendations are not bound by RelativelyLayout param.
             // To position them on the expected location, padding & margin are added to these views

             // Tabs should have a padding of the height of the search & recommendations container.
             RelativeLayout.LayoutParams tabsLayoutParams =
                     (RelativeLayout.LayoutParams) mPrimaryWorkTabsView.getLayoutParams();
             tabsLayoutParams.topMargin = topContainerHeight;
             mPrimaryWorkTabsView.setLayoutParams(tabsLayoutParams);

             // Instead of setting the top offset directly, we split the top offset into two values:
             // 1. topOffsetAfterAllViewsCollapsed: this is the top offset after all collapsible
             //    views are no longer visible on the screen.
             //    This value is set as the margin for the view pager.
             // 2. mMaxCollapsibleDistance
             //    This value is set as the padding for the recycler views in order to work with
             //    clipToPadding="false", which is an attribute for not showing top / bottom padding
             //    when a recycler view has not reached the top or bottom of the list.
             //    e.g. a list of 10 entries, only 3 entries are visible at a time.
             //         case 1: recycler view is scrolled to the top. Top padding is visible/
             //         (top padding)
             //         item 1
             //         item 2
             //         item 3
             //
             //         case 2: recycler view is scrolled to the middle. No padding is visible.
             //         item 4
             //         item 5
             //         item 6
             //
             //         case 3: recycler view is scrolled to the end. bottom padding is visible.
             //         item 8
             //         item 9
             //         item 10
             //         (bottom padding): not set in this case.
             //
             // When the views are first inflated, the sum of topOffsetAfterAllViewsCollapsed and
             // mMaxCollapsibleDistance should equal to the top container height.
             int topOffsetAfterAllViewsCollapsed =
                     topContainerHeight + mTabsHeight - mCollapsibleHeightForTabs;

             if (mPrimaryWorkTabsView.getVisibility() == View.VISIBLE) {
                 noWidgetsViewHeight += mTabsHeight;
             }

             RelativeLayout.LayoutParams viewPagerLayoutParams =
                     (RelativeLayout.LayoutParams) mPrimaryWorkViewPager.getLayoutParams();
             if (viewPagerLayoutParams.topMargin != topOffsetAfterAllViewsCollapsed) {
                 viewPagerLayoutParams.topMargin = topOffsetAfterAllViewsCollapsed;
                 mPrimaryWorkViewPager.setLayoutParams(viewPagerLayoutParams);
                 hasMarginOrPaddingUpdated = true;
             }

             if (mPrimaryRecyclerView.getPaddingTop() != mCollapsibleHeightForTabs) {
                 mPrimaryRecyclerView.setPadding(
                         mPrimaryRecyclerView.getPaddingLeft(),
                         mCollapsibleHeightForTabs,
                         mPrimaryRecyclerView.getPaddingRight(),
                         mPrimaryRecyclerView.getPaddingBottom());
                 hasMarginOrPaddingUpdated = true;
             }
             if (mWorkRecyclerView.getPaddingTop() != mCollapsibleHeightForTabs) {
                 mWorkRecyclerView.setPadding(
                         mWorkRecyclerView.getPaddingLeft(),
                         mCollapsibleHeightForTabs,
                         mWorkRecyclerView.getPaddingRight(),
                         mWorkRecyclerView.getPaddingBottom());
                 hasMarginOrPaddingUpdated = true;
             }
         } else {
             if (mPrimaryRecyclerView.getPaddingTop() != topContainerHeight) {
                 mPrimaryRecyclerView.setPadding(
                         mPrimaryRecyclerView.getPaddingLeft(),
                         topContainerHeight,
                         mPrimaryRecyclerView.getPaddingRight(),
                         mPrimaryRecyclerView.getPaddingBottom());
                 hasMarginOrPaddingUpdated = true;
             }
         }
         if (mSearchRecyclerView.getPaddingTop() != topContainerHeight) {
             mSearchRecyclerView.setPadding(
                     mSearchRecyclerView.getPaddingLeft(),
                     topContainerHeight,
                     mSearchRecyclerView.getPaddingRight(),
                     mSearchRecyclerView.getPaddingBottom());
             hasMarginOrPaddingUpdated = true;
         }
         if (mNoWidgetsView.getPaddingTop() != noWidgetsViewHeight) {
             mNoWidgetsView.setPadding(
                     mNoWidgetsView.getPaddingLeft(),
                     noWidgetsViewHeight,
                     mNoWidgetsView.getPaddingRight(),
                     mNoWidgetsView.getPaddingBottom());
             hasMarginOrPaddingUpdated = true;
         }
         return hasMarginOrPaddingUpdated;
     }

     @Override
     public void onScrollChanged() {
         int recyclerViewYOffset = mCurrentRecyclerView.getCurrentScrollY();
         if (recyclerViewYOffset < 0) return;
         mCurrentRecyclerViewScrollY = recyclerViewYOffset;
         if (mAnimator.isStarted()) {
             mAnimator.cancel();
         }
         applyVerticalTransition();
     }

     /**
      * Changes the displacement of collapsible views (e.g. title & widget recommendations) and fixed
      * views (e.g. recycler views, tabs) upon scrolling / content changes in the recycler view.
      */
     private void applyVerticalTransition() {
         if (mCollapsibleHeightForRecommendation > 0) {
             int yDisplacement = Math.max(-mCurrentRecyclerViewScrollY,
                     -mCollapsibleHeightForRecommendation);
             mViewHolder.mHeaderTitle.setTranslationY(yDisplacement);
             mViewHolder.mRecommendedWidgetsTable.setTranslationY(yDisplacement);
         }

         if (mCollapsibleHeightForSearch > 0) {
             int searchYDisplacement = Math.max(-mCurrentRecyclerViewScrollY,
                     -mCollapsibleHeightForSearch);
             mViewHolder.mSearchBarContainer.setTranslationY(searchYDisplacement);
         }

         if (mHasWorkProfile && mCollapsibleHeightForTabs > 0) {
             int yDisplacementForTabs = Math.max(-mCurrentRecyclerViewScrollY,
                     -mCollapsibleHeightForTabs);
             mPrimaryWorkTabsView.setTranslationY(yDisplacementForTabs);
         }
     }

     /** Resets any previous view translation. */
     public void reset(boolean animate) {
         if (mCurrentRecyclerViewScrollY == 0) {
             return;
         }
         if (mAnimator.isStarted()) {
             mAnimator.cancel();
         }

         if (animate) {
             mAnimator.setIntValues(mCurrentRecyclerViewScrollY, 0);
             mAnimator.addUpdateListener(this);
             mAnimator.setDuration(300);
             mAnimator.start();
         } else {
             mCurrentRecyclerViewScrollY = 0;
             applyVerticalTransition();
         }
     }

     /**
      * Returns {@code true} if a touch event should be intercepted by this controller.
      */
     public boolean onInterceptTouchEvent(MotionEvent event) {
         calculateMotionEventOffset(mTempOffset);
         event.offsetLocation(mTempOffset.x, mTempOffset.y);
         try {
             mShouldForwardToRecyclerView = mCurrentRecyclerView.onInterceptTouchEvent(event);
             return mShouldForwardToRecyclerView;
         } finally {
             event.offsetLocation(-mTempOffset.x, -mTempOffset.y);
         }
     }

     /**
      * Returns {@code true} if this controller has intercepted and consumed a touch event.
      */
     public boolean onTouchEvent(MotionEvent event) {
         if (mShouldForwardToRecyclerView) {
             calculateMotionEventOffset(mTempOffset);
             event.offsetLocation(mTempOffset.x, mTempOffset.y);
             try {
                 return mCurrentRecyclerView.onTouchEvent(event);
             } finally {
                 event.offsetLocation(-mTempOffset.x, -mTempOffset.y);
             }
         }
         return false;
     }

     private void calculateMotionEventOffset(Point p) {
         p.x = mViewHolder.mContainer.getLeft() - mCurrentRecyclerView.getLeft()
                 - mSearchAndRecommendationViewParent.getLeft();
         p.y = mViewHolder.mContainer.getTop() - mCurrentRecyclerView.getTop()
                 - mSearchAndRecommendationViewParent.getTop();
     }

     /** private the height, in pixel, + the vertical margins of a given view. */
     private static int measureHeightWithVerticalMargins(View view) {
         if (view.getVisibility() != View.VISIBLE) {
             return 0;
         }
         MarginLayoutParams marginLayoutParams = (MarginLayoutParams) view.getLayoutParams();
         return view.getMeasuredHeight() + marginLayoutParams.bottomMargin
                 + marginLayoutParams.topMargin;
     }

     @Override
     public void onAnimationUpdate(ValueAnimator animation) {
         mCurrentRecyclerViewScrollY = (Integer) animation.getAnimatedValue();
         applyVerticalTransition();
     }

     /**
      * A listener to be notified when there is a content change in the recycler view that may affect
      * the relative position of the search and recommendation container.
      */
     public interface OnContentChangeListener {
         /** Notifies a content change in the recycler view. */
         void onContentChanged();
     }
 }
	/*
	* Copyright (C) 2021 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.picker;

	import android.animation.ValueAnimator;
	import android.graphics.Point;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.ViewGroup.MarginLayoutParams;
	import android.widget.RelativeLayout;
	import android.widget.TextView;

	import androidx.annotation.Nullable;

	import com.android.launcher3.views.RecyclerViewFastScroller;
	import com.android.launcher3.widget.picker.WidgetsFullSheet.SearchAndRecommendationViewHolder;
	import com.android.launcher3.workprofile.PersonalWorkPagedView;

	/**
	* A controller which measures & updates {@link WidgetsFullSheet}'s views padding, margin and
	* vertical displacement upon scrolling.
	*/
	final class SearchAndRecommendationsScrollController implements
	RecyclerViewFastScroller.OnFastScrollChangeListener, ValueAnimator.AnimatorUpdateListener {
	private final boolean mHasWorkProfile;
	private final SearchAndRecommendationViewHolder mViewHolder;
	private final View mSearchAndRecommendationViewParent;
	private final WidgetsRecyclerView mPrimaryRecyclerView;
	private final WidgetsRecyclerView mSearchRecyclerView;
	private final TextView mNoWidgetsView;
	private final int mTabsHeight;
	private final ValueAnimator mAnimator = ValueAnimator.ofInt(0, 0);
	private final Point mTempOffset = new Point();
	private int mBottomInset;

	// The following are only non null if mHasWorkProfile is true.
	@Nullable private final WidgetsRecyclerView mWorkRecyclerView;
	@Nullable private final View mPrimaryWorkTabsView;
	@Nullable private final PersonalWorkPagedView mPrimaryWorkViewPager;

	private WidgetsRecyclerView mCurrentRecyclerView;
	private int mCurrentRecyclerViewScrollY = 0;

	private OnContentChangeListener mOnContentChangeListener = () -> onScrollChanged();

	/**
	* The vertical distance, in pixels, until the search is pinned at the top of the screen when
	* the user scrolls down the recycler view.
	*/
	private int mCollapsibleHeightForSearch = 0;
	/**
	* The vertical distance, in pixels, until the recommendation table disappears from the top of
	* the screen when the user scrolls down the recycler view.
	*/
	private int mCollapsibleHeightForRecommendation = 0;
	/**
	* The vertical distance, in pixels, until the tabs is pinned at the top of the screen when the
	* user scrolls down the recycler view.
	*
	* <p>Always 0 if there is no work profile.
	*/
	private int mCollapsibleHeightForTabs = 0;

	private boolean mShouldForwardToRecyclerView = false;

	SearchAndRecommendationsScrollController(
	boolean hasWorkProfile,
	int tabsHeight,
	SearchAndRecommendationViewHolder viewHolder,
	WidgetsRecyclerView primaryRecyclerView,
	@Nullable WidgetsRecyclerView workRecyclerView,
	WidgetsRecyclerView searchRecyclerView,
	@Nullable View personalWorkTabsView,
	@Nullable PersonalWorkPagedView primaryWorkViewPager,
	TextView noWidgetsView) {
	mHasWorkProfile = hasWorkProfile;
	mViewHolder = viewHolder;
	mViewHolder.mContainer.setSearchAndRecommendationScrollController(this);
	mSearchAndRecommendationViewParent = (View) mViewHolder.mContainer.getParent();
	mPrimaryRecyclerView = primaryRecyclerView;
	mWorkRecyclerView = workRecyclerView;
	mSearchRecyclerView = searchRecyclerView;
	mPrimaryWorkTabsView = personalWorkTabsView;
	mPrimaryWorkViewPager = primaryWorkViewPager;
	mTabsHeight = tabsHeight;
	mNoWidgetsView = noWidgetsView;
	setCurrentRecyclerView(mPrimaryRecyclerView, /* animateReset= */ false);
	}

	public void setCurrentRecyclerView(WidgetsRecyclerView currentRecyclerView) {
	setCurrentRecyclerView(currentRecyclerView, /* animateReset= */ true);
	}

	/** Sets the current active {@link WidgetsRecyclerView}. */
	private void setCurrentRecyclerView(WidgetsRecyclerView currentRecyclerView,
	boolean animateReset) {
	if (mCurrentRecyclerView == currentRecyclerView) {
	return;
	}
	if (mCurrentRecyclerView != null) {
	mCurrentRecyclerView.setOnContentChangeListener(null);
	}
	mCurrentRecyclerView = currentRecyclerView;
	mCurrentRecyclerView.setOnContentChangeListener(mOnContentChangeListener);
	reset(animateReset);
	}

	/**
	* Updates padding of {@link WidgetsFullSheet} contents to include {@code bottomInset} wherever
	* necessary.
	*/
	public boolean updateBottomInset(int bottomInset) {
	mBottomInset = bottomInset;
	return updateMarginAndPadding();
	}

	/**
	* Updates the margin and padding of {@link WidgetsFullSheet} to accumulate collapsible views.
	*
	* @return {@code true} if margins or/and padding of views in the search and recommendations
	* container have been updated.
	*/
	public boolean updateMarginAndPadding() {
	boolean hasMarginOrPaddingUpdated = false;
	mCollapsibleHeightForSearch = measureHeightWithVerticalMargins(mViewHolder.mHeaderTitle);
	mCollapsibleHeightForRecommendation =
	measureHeightWithVerticalMargins(mViewHolder.mHeaderTitle)
	+ measureHeightWithVerticalMargins(mViewHolder.mCollapseHandle)
	+ measureHeightWithVerticalMargins((View) mViewHolder.mSearchBarContainer)
	+ measureHeightWithVerticalMargins(mViewHolder.mRecommendedWidgetsTable);

	int topContainerHeight = measureHeightWithVerticalMargins(mViewHolder.mContainer);
	int noWidgetsViewHeight = topContainerHeight - mBottomInset;

	if (mHasWorkProfile) {
	mCollapsibleHeightForTabs = measureHeightWithVerticalMargins(mViewHolder.mHeaderTitle)
	+ measureHeightWithVerticalMargins(mViewHolder.mRecommendedWidgetsTable);
	// In a work profile setup, the full widget sheet contains the following views:
	// ------- (pinned) -\|
	// Widgets (collapsible) -\|---> LinearLayout for search & recommendations
	// Search bar (pinned) -\|
	// Widgets recommendation (collapsible)-\|
	// Personal \| Work (pinned)
	// View Pager
	//
	// Views after the search & recommendations are not bound by RelativelyLayout param.
	// To position them on the expected location, padding & margin are added to these views

	// Tabs should have a padding of the height of the search & recommendations container.
	RelativeLayout.LayoutParams tabsLayoutParams =
	(RelativeLayout.LayoutParams) mPrimaryWorkTabsView.getLayoutParams();
	tabsLayoutParams.topMargin = topContainerHeight;
	mPrimaryWorkTabsView.setLayoutParams(tabsLayoutParams);

	// Instead of setting the top offset directly, we split the top offset into two values:
	// 1. topOffsetAfterAllViewsCollapsed: this is the top offset after all collapsible
	// views are no longer visible on the screen.
	// This value is set as the margin for the view pager.
	// 2. mMaxCollapsibleDistance
	// This value is set as the padding for the recycler views in order to work with
	// clipToPadding="false", which is an attribute for not showing top / bottom padding
	// when a recycler view has not reached the top or bottom of the list.
	// e.g. a list of 10 entries, only 3 entries are visible at a time.
	// case 1: recycler view is scrolled to the top. Top padding is visible/
	// (top padding)
	// item 1
	// item 2
	// item 3
	//
	// case 2: recycler view is scrolled to the middle. No padding is visible.
	// item 4
	// item 5
	// item 6
	//
	// case 3: recycler view is scrolled to the end. bottom padding is visible.
	// item 8
	// item 9
	// item 10
	// (bottom padding): not set in this case.
	//
	// When the views are first inflated, the sum of topOffsetAfterAllViewsCollapsed and
	// mMaxCollapsibleDistance should equal to the top container height.
	int topOffsetAfterAllViewsCollapsed =
	topContainerHeight + mTabsHeight - mCollapsibleHeightForTabs;

	if (mPrimaryWorkTabsView.getVisibility() == View.VISIBLE) {
	noWidgetsViewHeight += mTabsHeight;
	}

	RelativeLayout.LayoutParams viewPagerLayoutParams =
	(RelativeLayout.LayoutParams) mPrimaryWorkViewPager.getLayoutParams();
	if (viewPagerLayoutParams.topMargin != topOffsetAfterAllViewsCollapsed) {
	viewPagerLayoutParams.topMargin = topOffsetAfterAllViewsCollapsed;
	mPrimaryWorkViewPager.setLayoutParams(viewPagerLayoutParams);
	hasMarginOrPaddingUpdated = true;
	}

	if (mPrimaryRecyclerView.getPaddingTop() != mCollapsibleHeightForTabs) {
	mPrimaryRecyclerView.setPadding(
	mPrimaryRecyclerView.getPaddingLeft(),
	mCollapsibleHeightForTabs,
	mPrimaryRecyclerView.getPaddingRight(),
	mPrimaryRecyclerView.getPaddingBottom());
	hasMarginOrPaddingUpdated = true;
	}
	if (mWorkRecyclerView.getPaddingTop() != mCollapsibleHeightForTabs) {
	mWorkRecyclerView.setPadding(
	mWorkRecyclerView.getPaddingLeft(),
	mCollapsibleHeightForTabs,
	mWorkRecyclerView.getPaddingRight(),
	mWorkRecyclerView.getPaddingBottom());
	hasMarginOrPaddingUpdated = true;
	}
	} else {
	if (mPrimaryRecyclerView.getPaddingTop() != topContainerHeight) {
	mPrimaryRecyclerView.setPadding(
	mPrimaryRecyclerView.getPaddingLeft(),
	topContainerHeight,
	mPrimaryRecyclerView.getPaddingRight(),
	mPrimaryRecyclerView.getPaddingBottom());
	hasMarginOrPaddingUpdated = true;
	}
	}
	if (mSearchRecyclerView.getPaddingTop() != topContainerHeight) {
	mSearchRecyclerView.setPadding(
	mSearchRecyclerView.getPaddingLeft(),
	topContainerHeight,
	mSearchRecyclerView.getPaddingRight(),
	mSearchRecyclerView.getPaddingBottom());
	hasMarginOrPaddingUpdated = true;
	}
	if (mNoWidgetsView.getPaddingTop() != noWidgetsViewHeight) {
	mNoWidgetsView.setPadding(
	mNoWidgetsView.getPaddingLeft(),
	noWidgetsViewHeight,
	mNoWidgetsView.getPaddingRight(),
	mNoWidgetsView.getPaddingBottom());
	hasMarginOrPaddingUpdated = true;
	}
	return hasMarginOrPaddingUpdated;
	}

	@Override
	public void onScrollChanged() {
	int recyclerViewYOffset = mCurrentRecyclerView.getCurrentScrollY();
	if (recyclerViewYOffset < 0) return;
	mCurrentRecyclerViewScrollY = recyclerViewYOffset;
	if (mAnimator.isStarted()) {
	mAnimator.cancel();
	}
	applyVerticalTransition();
	}

	/**
	* Changes the displacement of collapsible views (e.g. title & widget recommendations) and fixed
	* views (e.g. recycler views, tabs) upon scrolling / content changes in the recycler view.
	*/
	private void applyVerticalTransition() {
	if (mCollapsibleHeightForRecommendation > 0) {
	int yDisplacement = Math.max(-mCurrentRecyclerViewScrollY,
	-mCollapsibleHeightForRecommendation);
	mViewHolder.mHeaderTitle.setTranslationY(yDisplacement);
	mViewHolder.mRecommendedWidgetsTable.setTranslationY(yDisplacement);
	}

	if (mCollapsibleHeightForSearch > 0) {
	int searchYDisplacement = Math.max(-mCurrentRecyclerViewScrollY,
	-mCollapsibleHeightForSearch);
	mViewHolder.mSearchBarContainer.setTranslationY(searchYDisplacement);
	}

	if (mHasWorkProfile && mCollapsibleHeightForTabs > 0) {
	int yDisplacementForTabs = Math.max(-mCurrentRecyclerViewScrollY,
	-mCollapsibleHeightForTabs);
	mPrimaryWorkTabsView.setTranslationY(yDisplacementForTabs);
	}
	}

	/** Resets any previous view translation. */
	public void reset(boolean animate) {
	if (mCurrentRecyclerViewScrollY == 0) {
	return;
	}
	if (mAnimator.isStarted()) {
	mAnimator.cancel();
	}

	if (animate) {
	mAnimator.setIntValues(mCurrentRecyclerViewScrollY, 0);
	mAnimator.addUpdateListener(this);
	mAnimator.setDuration(300);
	mAnimator.start();
	} else {
	mCurrentRecyclerViewScrollY = 0;
	applyVerticalTransition();
	}
	}

	/**
	* Returns {@code true} if a touch event should be intercepted by this controller.
	*/
	public boolean onInterceptTouchEvent(MotionEvent event) {
	calculateMotionEventOffset(mTempOffset);
	event.offsetLocation(mTempOffset.x, mTempOffset.y);
	try {
	mShouldForwardToRecyclerView = mCurrentRecyclerView.onInterceptTouchEvent(event);
	return mShouldForwardToRecyclerView;
	} finally {
	event.offsetLocation(-mTempOffset.x, -mTempOffset.y);
	}
	}

	/**
	* Returns {@code true} if this controller has intercepted and consumed a touch event.
	*/
	public boolean onTouchEvent(MotionEvent event) {
	if (mShouldForwardToRecyclerView) {
	calculateMotionEventOffset(mTempOffset);
	event.offsetLocation(mTempOffset.x, mTempOffset.y);
	try {
	return mCurrentRecyclerView.onTouchEvent(event);
	} finally {
	event.offsetLocation(-mTempOffset.x, -mTempOffset.y);
	}
	}
	return false;
	}

	private void calculateMotionEventOffset(Point p) {
	p.x = mViewHolder.mContainer.getLeft() - mCurrentRecyclerView.getLeft()
	- mSearchAndRecommendationViewParent.getLeft();
	p.y = mViewHolder.mContainer.getTop() - mCurrentRecyclerView.getTop()
	- mSearchAndRecommendationViewParent.getTop();
	}

	/** private the height, in pixel, + the vertical margins of a given view. */
	private static int measureHeightWithVerticalMargins(View view) {
	if (view.getVisibility() != View.VISIBLE) {
	return 0;
	}
	MarginLayoutParams marginLayoutParams = (MarginLayoutParams) view.getLayoutParams();
	return view.getMeasuredHeight() + marginLayoutParams.bottomMargin
	+ marginLayoutParams.topMargin;
	}

	@Override
	public void onAnimationUpdate(ValueAnimator animation) {
	mCurrentRecyclerViewScrollY = (Integer) animation.getAnimatedValue();
	applyVerticalTransition();
	}

	/**
	* A listener to be notified when there is a content change in the recycler view that may affect
	* the relative position of the search and recommendation container.
	*/
	public interface OnContentChangeListener {
	/** Notifies a content change in the recycler view. */
	void onContentChanged();
	}
	}