car-stream-ui-lib/src/com/android/car/view/PagedListView.java - platform/packages/apps/Car/libs - Git at Google

 /*
  * Copyright (C) 2017 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package com.android.car.view;

 import android.content.Context;
 import android.content.res.TypedArray;
 import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.graphics.Rect;
 import android.os.Handler;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v7.widget.RecyclerView;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.FrameLayout;
 import android.widget.TextView;

 import com.android.car.stream.ui.R;

 /**
  * Custom {@link android.support.v7.widget.RecyclerView} that displays a list of items that
  * resembles a {@link android.widget.ListView} but also has page up and page down arrows
  * on the right side.
  */
 public class PagedListView extends FrameLayout {
     private static final String TAG = "PagedListView";

     /**
      * The amount of time after settling to wait before autoscrolling to the next page when the
      * user holds down a pagination button.
      */
     private static final int PAGINATION_HOLD_DELAY_MS = 400;

     private final CarRecyclerView mRecyclerView;
     private final CarLayoutManager mLayoutManager;
     private final PagedScrollBarView mScrollBarView;
     private final Handler mHandler = new Handler();
     private DividerDecoration mDecor;

     /** Maximum number of pages to show. Values < 0 show all pages. */
     private int mMaxPages = -1;
     /** Number of visible rows per page */
     private int mRowsPerPage = -1;

     /**
      * Used to check if there are more items added to the list.
      */
     private int mLastItemCount = 0;

     private RecyclerView.Adapter<? extends RecyclerView.ViewHolder> mAdapter;

     private boolean mNeedsFocus;
     private OnScrollBarListener mOnScrollBarListener;

     /**
      * Interface for a {@link android.support.v7.widget.RecyclerView.Adapter} to cap the
      * number of items.
      * <p>NOTE: it is still up to the adapter to use maxItems in
      * {@link android.support.v7.widget.RecyclerView.Adapter#getItemCount()}.
      *
      * the recommended way would be with:
      * <pre>
      * @Override
      * public int getItemCount() {
      *     return Math.min(super.getItemCount(), mMaxItems);
      * }
      * </pre>
      */
     public interface ItemCap {
         public static final int UNLIMITED = -1;

         /**
          * Sets the maximum number of items available in the adapter. A value less than '0'
          * means the list should not be capped.
          */
         void setMaxItems(int maxItems);
     }

     public PagedListView(Context context, AttributeSet attrs) {
         this(context, attrs, 0 /*defStyleAttrs*/, 0 /*defStyleRes*/);
     }

     public PagedListView(Context context, AttributeSet attrs, int defStyleAttrs) {
         this(context, attrs, defStyleAttrs, 0 /*defStyleRes*/);
     }

     public PagedListView(Context context, AttributeSet attrs, int defStyleAttrs, int defStyleRes) {
         super(context, attrs, defStyleAttrs, defStyleRes);
         TypedArray a = context.obtainStyledAttributes(
                 attrs, R.styleable.PagedListView, defStyleAttrs, defStyleRes);
         LayoutInflater.from(context)
                 .inflate(R.layout.car_paged_recycler_view, this /*root*/, true /*attachToRoot*/);
         int scrollContainerWidth = getResources().getDimensionPixelSize(
                 R.dimen.car_drawer_button_container_width);
         if (a.hasValue(R.styleable.PagedListView_scrollbarContainerWidth)) {
             scrollContainerWidth = a.getDimensionPixelSize(
                     R.styleable.PagedListView_scrollbarContainerWidth,
                     scrollContainerWidth);
             FrameLayout scrollContainer = (FrameLayout) findViewById(R.id.scroll_container);
             LayoutParams params = (LayoutParams) scrollContainer.getLayoutParams();
             params.width = scrollContainerWidth;
             scrollContainer.setLayoutParams(params);
         }

         boolean offsetScrollBar = a.getBoolean(R.styleable.PagedListView_offsetScrollBar, false);
         if (offsetScrollBar) {
             FrameLayout maxWidthLayout = (FrameLayout) findViewById(R.id.max_width_layout);
             LayoutParams params = (LayoutParams) maxWidthLayout.getLayoutParams();
             params.leftMargin = scrollContainerWidth;
             int rightMargin = a.getDimensionPixelSize(R.styleable.PagedListView_rightMargin, 0);
             params.rightMargin = rightMargin;
             maxWidthLayout.setLayoutParams(params);
         }
         boolean showDivider = a.getBoolean(R.styleable.PagedListView_showDivider, true);
         mDecor = showDivider
                 ? new DividerDecoration(getContext()) : new NoDividerDecoration(getContext());

         mRecyclerView = (CarRecyclerView) findViewById(R.id.recycler_view);
         boolean fadeLastItem = a.getBoolean(R.styleable.PagedListView_fadeLastItem, false);
         mRecyclerView.setFadeLastItem(fadeLastItem);
         boolean offsetRows = a.getBoolean(R.styleable.PagedListView_offsetRows, false);
         a.recycle();

         mMaxPages = getDefaultMaxPages();

         mLayoutManager = new CarLayoutManager(context);
         mLayoutManager.setOffsetRows(offsetRows);
         mLayoutManager.setItemsChangedListener(mItemsChangedListener);
         mRecyclerView.setLayoutManager(mLayoutManager);
         mRecyclerView.addItemDecoration(mDecor);
         mRecyclerView.setOnScrollListener(mOnScrollListener);
         mRecyclerView.getRecycledViewPool().setMaxRecycledViews(0, 12);
         mRecyclerView.setItemAnimator(new CarItemAnimator(mLayoutManager));

         mScrollBarView = (PagedScrollBarView) findViewById(R.id.paged_scroll_view);
         mScrollBarView.setPaginationListener(new PagedScrollBarView.PaginationListener() {
             @Override
             public void onPaginate(int direction) {
                 if (direction == PagedScrollBarView.PaginationListener.PAGE_UP) {
                     mRecyclerView.pageUp();
                 } else if (direction == PagedScrollBarView.PaginationListener.PAGE_DOWN) {
                     mRecyclerView.pageDown();
                 } else {
                     Log.e(TAG, "Unknown pagination direction (" + direction + ")");
                 }
             }
         });

         setAutoDayNightMode();
         updatePaginationButtons(false /*animate*/);
     }

     @Override
     protected void onDetachedFromWindow() {
         super.onDetachedFromWindow();
         mHandler.removeCallbacks(mUpdatePaginationRunnable);
     }

     @Override
     public boolean onInterceptTouchEvent(MotionEvent e) {
         if (e.getAction() == MotionEvent.ACTION_DOWN) {
             // The user has interacted with the list using touch. All movements will now paginate
             // the list.
             mLayoutManager.setRowOffsetMode(CarLayoutManager.ROW_OFFSET_MODE_PAGE);
         }
         return super.onInterceptTouchEvent(e);
     }

     @Override
     public void requestChildFocus(View child, View focused) {
         super.requestChildFocus(child, focused);
         // The user has interacted with the list using the controller. Movements through the list
         // will now be one row at a time.
         mLayoutManager.setRowOffsetMode(CarLayoutManager.ROW_OFFSET_MODE_INDIVIDUAL);
     }

     public int positionOf(@Nullable View v) {
         if (v == null || v.getParent() != mRecyclerView) {
             return -1;
         }
         return mLayoutManager.getPosition(v);
     }

     @NonNull
     public CarRecyclerView getRecyclerView() {
         return mRecyclerView;
     }

     public void scrollToPosition(int position) {
         mLayoutManager.scrollToPosition(position);

         // Sometimes #scrollToPosition doesn't change the scroll state so we need to make sure
         // the pagination arrows actually get updated.
         mHandler.post(mUpdatePaginationRunnable);
     }

     /**
      * Sets the adapter for the list.
      * <p>It <em>must</em> implement {@link ItemCap}, otherwise, will throw
      * an {@link IllegalArgumentException}.
      */
     public void setAdapter(
             @NonNull RecyclerView.Adapter<? extends RecyclerView.ViewHolder> adapter) {
         if (!(adapter instanceof ItemCap)) {
             throw new IllegalArgumentException("ERROR: adapter "
                     + "[" + adapter.getClass().getCanonicalName() + "] MUST implement ItemCap");
         }

         mAdapter = adapter;
         mRecyclerView.setAdapter(adapter);
         tryUpdateMaxPages();
     }

     @NonNull
     public CarLayoutManager getLayoutManager() {
         return mLayoutManager;
     }

     @Nullable
     @SuppressWarnings("unchecked")
     public RecyclerView.Adapter<? extends RecyclerView.ViewHolder> getAdapter() {
         return mRecyclerView.getAdapter();
     }

     public void setMaxPages(int maxPages) {
         mMaxPages = maxPages;
         tryUpdateMaxPages();
     }

     public int getMaxPages() {
         return mMaxPages;
     }

     public void resetMaxPages() {
         mMaxPages = getDefaultMaxPages();
     }

     public void setDefaultItemDecoration(DividerDecoration decor) {
         removeDefaultItemDecoration();
         mDecor = decor;
         addItemDecoration(mDecor);
     }

     public void removeDefaultItemDecoration() {
         mRecyclerView.removeItemDecoration(mDecor);
     }

     public void addItemDecoration(@NonNull RecyclerView.ItemDecoration decor) {
         mRecyclerView.addItemDecoration(decor);
     }

     public void removeItemDecoration(@NonNull RecyclerView.ItemDecoration decor) {
         mRecyclerView.removeItemDecoration(decor);
     }

     public void setAutoDayNightMode() {
         mScrollBarView.setAutoDayNightMode();
         mDecor.updateDividerColor();
     }

     public void setLightMode() {
         mScrollBarView.setLightMode();
         mDecor.updateDividerColor();
     }

     public void setDarkMode() {
         mScrollBarView.setDarkMode();
         mDecor.updateDividerColor();
     }

     public void setOnScrollBarListener(OnScrollBarListener listener) {
         mOnScrollBarListener = listener;
     }

     /** Returns the page the given position is on, starting with page 0. */
     public int getPage(int position) {
         if (mRowsPerPage == -1) {
             return -1;
         }
         return position / mRowsPerPage;
     }

     /** Returns the default number of pages the list should have */
     protected int getDefaultMaxPages() {
         // assume list shown in response to a click, so, reduce number of clicks by one
         //return ProjectionUtils.getMaxClicks(getContext().getContentResolver()) - 1;
         return 5;
     }

     private void tryUpdateMaxPages() {
         if (mAdapter == null) {
             return;
         }

         View firstChild = mLayoutManager.getChildAt(0);
         int firstRowHeight = firstChild == null ? 0 : firstChild.getHeight();
         mRowsPerPage = firstRowHeight == 0 ? 1 : getHeight() / firstRowHeight;

         int newMaxItems;
         if (mMaxPages < 0) {
             newMaxItems = -1;
         } else if (mMaxPages == 0) {
             // At the last click of 6 click limit, we show one more warning item at the top of menu.
             newMaxItems = mRowsPerPage + 1;
         } else {
             newMaxItems = mRowsPerPage * mMaxPages;
         }

         int originalCount = mAdapter.getItemCount();
         ((ItemCap) mAdapter).setMaxItems(newMaxItems);
         int newCount = mAdapter.getItemCount();
         if (newCount < originalCount) {
             mAdapter.notifyItemRangeChanged(newCount, originalCount);
         } else if (newCount > originalCount) {
             mAdapter.notifyItemInserted(originalCount);
         }
     }

     @Override
     public void onLayout(boolean changed, int left, int top, int right, int bottom) {
         // if a late item is added to the top of the layout after the layout is stabilized, causing
         // the former top item to be pushed to the 2nd page, the focus will still be on the former
         // top item. Since our car layout manager tries to scroll the viewport so that the focused
         // item is visible, the view port will be on the 2nd page. That means the newly added item
         // will not be visible, on the first page.

         // what we want to do is: if the formerly focused item is the first one in the list, any
         // item added above it will make the focus to move to the new first item.
         // if the focus is not on the formerly first item, then we don't need to do anything. Let
         // the layout manager do the job and scroll the viewport so the currently focused item
         // is visible.

         // we need to calculate whether we want to request focus here, before the super call,
         // because after the super call, the first born might be changed.
         View focusedChild = mLayoutManager.getFocusedChild();
         View firstBorn = mLayoutManager.getChildAt(0);

         super.onLayout(changed, left, top, right, bottom);

         if (mAdapter != null) {
             int itemCount = mAdapter.getItemCount();
            // if () {
                 Log.d(TAG, String.format(
                         "onLayout hasFocus: %s, mLastItemCount: %s, itemCount: %s, focusedChild: " +
                                 "%s, firstBorn: %s, isInTouchMode: %s, mNeedsFocus: %s",
                         hasFocus(), mLastItemCount, itemCount, focusedChild, firstBorn,
                         isInTouchMode(), mNeedsFocus));
           //  }
             tryUpdateMaxPages();
             // This is a workaround for missing focus because isInTouchMode() is not always
             // returning the right value.
             // This is okay for the Engine release since focus is always showing.
             // However, in Tala and Fender, we want to show focus only when the user uses
             // hardware controllers, so we need to revisit this logic. b/22990605.
             if (mNeedsFocus && itemCount > 0) {
                 if (focusedChild == null) {
                     requestFocusFromTouch();
                 }
                 mNeedsFocus = false;
             }
             if (itemCount > mLastItemCount && focusedChild == firstBorn &&
                     getContext().getResources().getBoolean(R.bool.has_wheel)) {
                 requestFocusFromTouch();
             }
             mLastItemCount = itemCount;
         }
         updatePaginationButtons(true /*animate*/);
     }

     @Override
     public boolean requestFocus(int direction, Rect rect) {
         if (getContext().getResources().getBoolean(R.bool.has_wheel)) {
             mNeedsFocus = true;
         }
         return super.requestFocus(direction, rect);
     }

     public View findViewByPosition(int position) {
         return mLayoutManager.findViewByPosition(position);
     }

     private void updatePaginationButtons(boolean animate) {
         boolean isAtTop = mLayoutManager.isAtTop();
         boolean isAtBottom = mLayoutManager.isAtBottom();
         if (isAtTop && isAtBottom) {
             mScrollBarView.setVisibility(View.INVISIBLE);
         } else {
             mScrollBarView.setVisibility(View.VISIBLE);
         }
         mScrollBarView.setUpEnabled(!isAtTop);
         mScrollBarView.setDownEnabled(!isAtBottom);

         mScrollBarView.setParameters(
                 mRecyclerView.computeVerticalScrollRange(),
                 mRecyclerView.computeVerticalScrollOffset(),
                 mRecyclerView.computeVerticalScrollExtent(),
                 animate);
         invalidate();
     }

     private final RecyclerView.OnScrollListener mOnScrollListener =
             new RecyclerView.OnScrollListener() {

         @Override
         public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
             if (mOnScrollBarListener != null) {
                 if (!mLayoutManager.isAtTop() && mLayoutManager.isAtBottom()) {
                     mOnScrollBarListener.onReachBottom();
                 }
                 if (mLayoutManager.isAtTop() || !mLayoutManager.isAtBottom()) {
                     mOnScrollBarListener.onLeaveBottom();
                 }
             }
             updatePaginationButtons(false);
         }

         @Override
         public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
             if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                 mHandler.postDelayed(mPaginationRunnable, PAGINATION_HOLD_DELAY_MS);
             }
         }
     };
     private final Runnable mPaginationRunnable = new Runnable() {
         @Override
         public void run() {
             boolean upPressed = mScrollBarView.isUpPressed();
             boolean downPressed = mScrollBarView.isDownPressed();
             if (upPressed && downPressed) {
                 // noop
             } else if (upPressed) {
                 mRecyclerView.pageUp();
             } else if (downPressed) {
                 mRecyclerView.pageDown();
             }
         }
     };

     private final Runnable mUpdatePaginationRunnable = new Runnable() {
         @Override
         public void run() {
             updatePaginationButtons(true /*animate*/);
         }
     };

     private final CarLayoutManager.OnItemsChangedListener mItemsChangedListener =
             new CarLayoutManager.OnItemsChangedListener() {
                 @Override
                 public void onItemsChanged() {
                     updatePaginationButtons(true /*animate*/);
                 }
             };

     abstract static public class OnScrollBarListener {
         public void onReachBottom() {}
         public void onLeaveBottom() {}
     }

     public static class DividerDecoration extends RecyclerView.ItemDecoration {
         protected final Paint mPaint;
         protected final int mDividerHeight;
         protected final Context mContext;


         public DividerDecoration(Context context) {
             mContext = context;
             mPaint = new Paint();
             updateDividerColor();
             mDividerHeight = mContext.getResources()
                     .getDimensionPixelSize(R.dimen.car_divider_height);
         }

         @Override
         public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
             final int left = getLeft(parent.getChildAt(0));
             final int right = parent.getWidth() - parent.getPaddingRight();
             int top;
             int bottom;

             c.drawRect(left, 0, right, mDividerHeight, mPaint);

             final int childCount = parent.getChildCount();
             for (int i = 0; i < childCount; i++) {
                 final View child = parent.getChildAt(i);
                 final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
                         .getLayoutParams();
                 bottom = child.getBottom() - params.bottomMargin;
                 top = bottom - mDividerHeight;
                 if (top > 0) {
                     c.drawRect(left, top, right, bottom, mPaint);
                 }
             }
         }

         /**
          * Updates the list divider color which may have changed due to a day night transition.
          */
         public void updateDividerColor() {
             mPaint.setColor(mContext.getResources().getColor(R.color.car_list_divider));
         }

         /**
          * Find the left edge of the decoration line. It should be left aligned with the left edge
          * of the first {@link android.widget.TextView}.
          */
         private int getLeft(View root) {
             if (root == null) {
                 return 0;
             }
             View view = findTextView(root);
             if (view == null) {
                 view = root;
             }
             int left = 0;
             while (view != null && view != root) {
                 left += view.getLeft();
                 view = (View) view.getParent();
             }
             return left;
         }

         private TextView findTextView(View root) {
             if (root == null) {
                 return null;
             }
             if (root instanceof TextView) {
                 return (TextView) root;
             }
             if (root instanceof ViewGroup) {
                 ViewGroup parent = (ViewGroup) root;
                 final int childCount = parent.getChildCount();
                 for(int i = 0; i < childCount; i++) {
                     TextView tv = findTextView(parent.getChildAt(i));
                     if (tv != null) {
                         return tv;
                     }
                 }
             }
             return null;
         }
     }

     public static class NoDividerDecoration extends DividerDecoration {
         public NoDividerDecoration(Context context) {
             super(context);
         }

         @Override
         public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {}
     }
 }
	/*
	* Copyright (C) 2017 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package com.android.car.view;

	import android.content.Context;
	import android.content.res.TypedArray;
	import android.graphics.Canvas;
	import android.graphics.Paint;
	import android.graphics.Rect;
	import android.os.Handler;
	import android.support.annotation.NonNull;
	import android.support.annotation.Nullable;
	import android.support.v7.widget.RecyclerView;
	import android.util.AttributeSet;
	import android.util.Log;
	import android.view.LayoutInflater;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.ViewGroup;
	import android.widget.FrameLayout;
	import android.widget.TextView;

	import com.android.car.stream.ui.R;

	/**
	* Custom {@link android.support.v7.widget.RecyclerView} that displays a list of items that
	* resembles a {@link android.widget.ListView} but also has page up and page down arrows
	* on the right side.
	*/
	public class PagedListView extends FrameLayout {
	private static final String TAG = "PagedListView";

	/**
	* The amount of time after settling to wait before autoscrolling to the next page when the
	* user holds down a pagination button.
	*/
	private static final int PAGINATION_HOLD_DELAY_MS = 400;

	private final CarRecyclerView mRecyclerView;
	private final CarLayoutManager mLayoutManager;
	private final PagedScrollBarView mScrollBarView;
	private final Handler mHandler = new Handler();
	private DividerDecoration mDecor;

	/** Maximum number of pages to show. Values < 0 show all pages. */
	private int mMaxPages = -1;
	/** Number of visible rows per page */
	private int mRowsPerPage = -1;

	/**
	* Used to check if there are more items added to the list.
	*/
	private int mLastItemCount = 0;

	private RecyclerView.Adapter<? extends RecyclerView.ViewHolder> mAdapter;

	private boolean mNeedsFocus;
	private OnScrollBarListener mOnScrollBarListener;

	/**
	* Interface for a {@link android.support.v7.widget.RecyclerView.Adapter} to cap the
	* number of items.
	* <p>NOTE: it is still up to the adapter to use maxItems in
	* {@link android.support.v7.widget.RecyclerView.Adapter#getItemCount()}.
	*
	* the recommended way would be with:
	* <pre>
	* @Override
	* public int getItemCount() {
	* return Math.min(super.getItemCount(), mMaxItems);
	* }
	* </pre>
	*/
	public interface ItemCap {
	public static final int UNLIMITED = -1;

	/**
	* Sets the maximum number of items available in the adapter. A value less than '0'
	* means the list should not be capped.
	*/
	void setMaxItems(int maxItems);
	}

	public PagedListView(Context context, AttributeSet attrs) {
	this(context, attrs, 0 /defStyleAttrs/, 0 /defStyleRes/);
	}

	public PagedListView(Context context, AttributeSet attrs, int defStyleAttrs) {
	this(context, attrs, defStyleAttrs, 0 /defStyleRes/);
	}

	public PagedListView(Context context, AttributeSet attrs, int defStyleAttrs, int defStyleRes) {
	super(context, attrs, defStyleAttrs, defStyleRes);
	TypedArray a = context.obtainStyledAttributes(
	attrs, R.styleable.PagedListView, defStyleAttrs, defStyleRes);
	LayoutInflater.from(context)
	.inflate(R.layout.car_paged_recycler_view, this /root/, true /attachToRoot/);
	int scrollContainerWidth = getResources().getDimensionPixelSize(
	R.dimen.car_drawer_button_container_width);
	if (a.hasValue(R.styleable.PagedListView_scrollbarContainerWidth)) {
	scrollContainerWidth = a.getDimensionPixelSize(
	R.styleable.PagedListView_scrollbarContainerWidth,
	scrollContainerWidth);
	FrameLayout scrollContainer = (FrameLayout) findViewById(R.id.scroll_container);
	LayoutParams params = (LayoutParams) scrollContainer.getLayoutParams();
	params.width = scrollContainerWidth;
	scrollContainer.setLayoutParams(params);
	}

	boolean offsetScrollBar = a.getBoolean(R.styleable.PagedListView_offsetScrollBar, false);
	if (offsetScrollBar) {
	FrameLayout maxWidthLayout = (FrameLayout) findViewById(R.id.max_width_layout);
	LayoutParams params = (LayoutParams) maxWidthLayout.getLayoutParams();
	params.leftMargin = scrollContainerWidth;
	int rightMargin = a.getDimensionPixelSize(R.styleable.PagedListView_rightMargin, 0);
	params.rightMargin = rightMargin;
	maxWidthLayout.setLayoutParams(params);
	}
	boolean showDivider = a.getBoolean(R.styleable.PagedListView_showDivider, true);
	mDecor = showDivider
	? new DividerDecoration(getContext()) : new NoDividerDecoration(getContext());

	mRecyclerView = (CarRecyclerView) findViewById(R.id.recycler_view);
	boolean fadeLastItem = a.getBoolean(R.styleable.PagedListView_fadeLastItem, false);
	mRecyclerView.setFadeLastItem(fadeLastItem);
	boolean offsetRows = a.getBoolean(R.styleable.PagedListView_offsetRows, false);
	a.recycle();

	mMaxPages = getDefaultMaxPages();

	mLayoutManager = new CarLayoutManager(context);
	mLayoutManager.setOffsetRows(offsetRows);
	mLayoutManager.setItemsChangedListener(mItemsChangedListener);
	mRecyclerView.setLayoutManager(mLayoutManager);
	mRecyclerView.addItemDecoration(mDecor);
	mRecyclerView.setOnScrollListener(mOnScrollListener);
	mRecyclerView.getRecycledViewPool().setMaxRecycledViews(0, 12);
	mRecyclerView.setItemAnimator(new CarItemAnimator(mLayoutManager));

	mScrollBarView = (PagedScrollBarView) findViewById(R.id.paged_scroll_view);
	mScrollBarView.setPaginationListener(new PagedScrollBarView.PaginationListener() {
	@Override
	public void onPaginate(int direction) {
	if (direction == PagedScrollBarView.PaginationListener.PAGE_UP) {
	mRecyclerView.pageUp();
	} else if (direction == PagedScrollBarView.PaginationListener.PAGE_DOWN) {
	mRecyclerView.pageDown();
	} else {
	Log.e(TAG, "Unknown pagination direction (" + direction + ")");
	}
	}
	});

	setAutoDayNightMode();
	updatePaginationButtons(false /animate/);
	}

	@Override
	protected void onDetachedFromWindow() {
	super.onDetachedFromWindow();
	mHandler.removeCallbacks(mUpdatePaginationRunnable);
	}

	@Override
	public boolean onInterceptTouchEvent(MotionEvent e) {
	if (e.getAction() == MotionEvent.ACTION_DOWN) {
	// The user has interacted with the list using touch. All movements will now paginate
	// the list.
	mLayoutManager.setRowOffsetMode(CarLayoutManager.ROW_OFFSET_MODE_PAGE);
	}
	return super.onInterceptTouchEvent(e);
	}

	@Override
	public void requestChildFocus(View child, View focused) {
	super.requestChildFocus(child, focused);
	// The user has interacted with the list using the controller. Movements through the list
	// will now be one row at a time.
	mLayoutManager.setRowOffsetMode(CarLayoutManager.ROW_OFFSET_MODE_INDIVIDUAL);
	}

	public int positionOf(@Nullable View v) {
	if (v == null \|\| v.getParent() != mRecyclerView) {
	return -1;
	}
	return mLayoutManager.getPosition(v);
	}

	@NonNull
	public CarRecyclerView getRecyclerView() {
	return mRecyclerView;
	}

	public void scrollToPosition(int position) {
	mLayoutManager.scrollToPosition(position);

	// Sometimes #scrollToPosition doesn't change the scroll state so we need to make sure
	// the pagination arrows actually get updated.
	mHandler.post(mUpdatePaginationRunnable);
	}

	/**
	* Sets the adapter for the list.
	* <p>It <em>must</em> implement {@link ItemCap}, otherwise, will throw
	* an {@link IllegalArgumentException}.
	*/
	public void setAdapter(
	@NonNull RecyclerView.Adapter<? extends RecyclerView.ViewHolder> adapter) {
	if (!(adapter instanceof ItemCap)) {
	throw new IllegalArgumentException("ERROR: adapter "
	+ "[" + adapter.getClass().getCanonicalName() + "] MUST implement ItemCap");
	}

	mAdapter = adapter;
	mRecyclerView.setAdapter(adapter);
	tryUpdateMaxPages();
	}

	@NonNull
	public CarLayoutManager getLayoutManager() {
	return mLayoutManager;
	}

	@Nullable
	@SuppressWarnings("unchecked")
	public RecyclerView.Adapter<? extends RecyclerView.ViewHolder> getAdapter() {
	return mRecyclerView.getAdapter();
	}

	public void setMaxPages(int maxPages) {
	mMaxPages = maxPages;
	tryUpdateMaxPages();
	}

	public int getMaxPages() {
	return mMaxPages;
	}

	public void resetMaxPages() {
	mMaxPages = getDefaultMaxPages();
	}

	public void setDefaultItemDecoration(DividerDecoration decor) {
	removeDefaultItemDecoration();
	mDecor = decor;
	addItemDecoration(mDecor);
	}

	public void removeDefaultItemDecoration() {
	mRecyclerView.removeItemDecoration(mDecor);
	}

	public void addItemDecoration(@NonNull RecyclerView.ItemDecoration decor) {
	mRecyclerView.addItemDecoration(decor);
	}

	public void removeItemDecoration(@NonNull RecyclerView.ItemDecoration decor) {
	mRecyclerView.removeItemDecoration(decor);
	}

	public void setAutoDayNightMode() {
	mScrollBarView.setAutoDayNightMode();
	mDecor.updateDividerColor();
	}

	public void setLightMode() {
	mScrollBarView.setLightMode();
	mDecor.updateDividerColor();
	}

	public void setDarkMode() {
	mScrollBarView.setDarkMode();
	mDecor.updateDividerColor();
	}

	public void setOnScrollBarListener(OnScrollBarListener listener) {
	mOnScrollBarListener = listener;
	}

	/** Returns the page the given position is on, starting with page 0. */
	public int getPage(int position) {
	if (mRowsPerPage == -1) {
	return -1;
	}
	return position / mRowsPerPage;
	}

	/** Returns the default number of pages the list should have */
	protected int getDefaultMaxPages() {
	// assume list shown in response to a click, so, reduce number of clicks by one
	//return ProjectionUtils.getMaxClicks(getContext().getContentResolver()) - 1;
	return 5;
	}

	private void tryUpdateMaxPages() {
	if (mAdapter == null) {
	return;
	}

	View firstChild = mLayoutManager.getChildAt(0);
	int firstRowHeight = firstChild == null ? 0 : firstChild.getHeight();
	mRowsPerPage = firstRowHeight == 0 ? 1 : getHeight() / firstRowHeight;

	int newMaxItems;
	if (mMaxPages < 0) {
	newMaxItems = -1;
	} else if (mMaxPages == 0) {
	// At the last click of 6 click limit, we show one more warning item at the top of menu.
	newMaxItems = mRowsPerPage + 1;
	} else {
	newMaxItems = mRowsPerPage * mMaxPages;
	}

	int originalCount = mAdapter.getItemCount();
	((ItemCap) mAdapter).setMaxItems(newMaxItems);
	int newCount = mAdapter.getItemCount();
	if (newCount < originalCount) {
	mAdapter.notifyItemRangeChanged(newCount, originalCount);
	} else if (newCount > originalCount) {
	mAdapter.notifyItemInserted(originalCount);
	}
	}

	@Override
	public void onLayout(boolean changed, int left, int top, int right, int bottom) {
	// if a late item is added to the top of the layout after the layout is stabilized, causing
	// the former top item to be pushed to the 2nd page, the focus will still be on the former
	// top item. Since our car layout manager tries to scroll the viewport so that the focused
	// item is visible, the view port will be on the 2nd page. That means the newly added item
	// will not be visible, on the first page.

	// what we want to do is: if the formerly focused item is the first one in the list, any
	// item added above it will make the focus to move to the new first item.
	// if the focus is not on the formerly first item, then we don't need to do anything. Let
	// the layout manager do the job and scroll the viewport so the currently focused item
	// is visible.

	// we need to calculate whether we want to request focus here, before the super call,
	// because after the super call, the first born might be changed.
	View focusedChild = mLayoutManager.getFocusedChild();
	View firstBorn = mLayoutManager.getChildAt(0);

	super.onLayout(changed, left, top, right, bottom);

	if (mAdapter != null) {
	int itemCount = mAdapter.getItemCount();
	// if () {
	Log.d(TAG, String.format(
	"onLayout hasFocus: %s, mLastItemCount: %s, itemCount: %s, focusedChild: " +
	"%s, firstBorn: %s, isInTouchMode: %s, mNeedsFocus: %s",
	hasFocus(), mLastItemCount, itemCount, focusedChild, firstBorn,
	isInTouchMode(), mNeedsFocus));
	// }
	tryUpdateMaxPages();
	// This is a workaround for missing focus because isInTouchMode() is not always
	// returning the right value.
	// This is okay for the Engine release since focus is always showing.
	// However, in Tala and Fender, we want to show focus only when the user uses
	// hardware controllers, so we need to revisit this logic. b/22990605.
	if (mNeedsFocus && itemCount > 0) {
	if (focusedChild == null) {
	requestFocusFromTouch();
	}
	mNeedsFocus = false;
	}
	if (itemCount > mLastItemCount && focusedChild == firstBorn &&
	getContext().getResources().getBoolean(R.bool.has_wheel)) {
	requestFocusFromTouch();
	}
	mLastItemCount = itemCount;
	}
	updatePaginationButtons(true /animate/);
	}

	@Override
	public boolean requestFocus(int direction, Rect rect) {
	if (getContext().getResources().getBoolean(R.bool.has_wheel)) {
	mNeedsFocus = true;
	}
	return super.requestFocus(direction, rect);
	}

	public View findViewByPosition(int position) {
	return mLayoutManager.findViewByPosition(position);
	}

	private void updatePaginationButtons(boolean animate) {
	boolean isAtTop = mLayoutManager.isAtTop();
	boolean isAtBottom = mLayoutManager.isAtBottom();
	if (isAtTop && isAtBottom) {
	mScrollBarView.setVisibility(View.INVISIBLE);
	} else {
	mScrollBarView.setVisibility(View.VISIBLE);
	}
	mScrollBarView.setUpEnabled(!isAtTop);
	mScrollBarView.setDownEnabled(!isAtBottom);

	mScrollBarView.setParameters(
	mRecyclerView.computeVerticalScrollRange(),
	mRecyclerView.computeVerticalScrollOffset(),
	mRecyclerView.computeVerticalScrollExtent(),
	animate);
	invalidate();
	}

	private final RecyclerView.OnScrollListener mOnScrollListener =
	new RecyclerView.OnScrollListener() {

	@Override
	public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
	if (mOnScrollBarListener != null) {
	if (!mLayoutManager.isAtTop() && mLayoutManager.isAtBottom()) {
	mOnScrollBarListener.onReachBottom();
	}
	if (mLayoutManager.isAtTop() \|\| !mLayoutManager.isAtBottom()) {
	mOnScrollBarListener.onLeaveBottom();
	}
	}
	updatePaginationButtons(false);
	}

	@Override
	public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
	if (newState == RecyclerView.SCROLL_STATE_IDLE) {
	mHandler.postDelayed(mPaginationRunnable, PAGINATION_HOLD_DELAY_MS);
	}
	}
	};
	private final Runnable mPaginationRunnable = new Runnable() {
	@Override
	public void run() {
	boolean upPressed = mScrollBarView.isUpPressed();
	boolean downPressed = mScrollBarView.isDownPressed();
	if (upPressed && downPressed) {
	// noop
	} else if (upPressed) {
	mRecyclerView.pageUp();
	} else if (downPressed) {
	mRecyclerView.pageDown();
	}
	}
	};

	private final Runnable mUpdatePaginationRunnable = new Runnable() {
	@Override
	public void run() {
	updatePaginationButtons(true /animate/);
	}
	};

	private final CarLayoutManager.OnItemsChangedListener mItemsChangedListener =
	new CarLayoutManager.OnItemsChangedListener() {
	@Override
	public void onItemsChanged() {
	updatePaginationButtons(true /animate/);
	}
	};

	abstract static public class OnScrollBarListener {
	public void onReachBottom() {}
	public void onLeaveBottom() {}
	}

	public static class DividerDecoration extends RecyclerView.ItemDecoration {
	protected final Paint mPaint;
	protected final int mDividerHeight;
	protected final Context mContext;


	public DividerDecoration(Context context) {
	mContext = context;
	mPaint = new Paint();
	updateDividerColor();
	mDividerHeight = mContext.getResources()
	.getDimensionPixelSize(R.dimen.car_divider_height);
	}

	@Override
	public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {
	final int left = getLeft(parent.getChildAt(0));
	final int right = parent.getWidth() - parent.getPaddingRight();
	int top;
	int bottom;

	c.drawRect(left, 0, right, mDividerHeight, mPaint);

	final int childCount = parent.getChildCount();
	for (int i = 0; i < childCount; i++) {
	final View child = parent.getChildAt(i);
	final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
	.getLayoutParams();
	bottom = child.getBottom() - params.bottomMargin;
	top = bottom - mDividerHeight;
	if (top > 0) {
	c.drawRect(left, top, right, bottom, mPaint);
	}
	}
	}

	/**
	* Updates the list divider color which may have changed due to a day night transition.
	*/
	public void updateDividerColor() {
	mPaint.setColor(mContext.getResources().getColor(R.color.car_list_divider));
	}

	/**
	* Find the left edge of the decoration line. It should be left aligned with the left edge
	* of the first {@link android.widget.TextView}.
	*/
	private int getLeft(View root) {
	if (root == null) {
	return 0;
	}
	View view = findTextView(root);
	if (view == null) {
	view = root;
	}
	int left = 0;
	while (view != null && view != root) {
	left += view.getLeft();
	view = (View) view.getParent();
	}
	return left;
	}

	private TextView findTextView(View root) {
	if (root == null) {
	return null;
	}
	if (root instanceof TextView) {
	return (TextView) root;
	}
	if (root instanceof ViewGroup) {
	ViewGroup parent = (ViewGroup) root;
	final int childCount = parent.getChildCount();
	for(int i = 0; i < childCount; i++) {
	TextView tv = findTextView(parent.getChildAt(i));
	if (tv != null) {
	return tv;
	}
	}
	}
	return null;
	}
	}

	public static class NoDividerDecoration extends DividerDecoration {
	public NoDividerDecoration(Context context) {
	super(context);
	}

	@Override
	public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state) {}
	}
	}