packages/SystemUI/src/com/android/systemui/recent/RecentsVerticalScrollView.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2011 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.android.systemui.recent;

 import android.animation.LayoutTransition;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.database.DataSetObserver;
 import android.graphics.Canvas;
 import android.util.AttributeSet;
 import android.util.DisplayMetrics;
 import android.util.FloatMath;
 import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewConfiguration;
 import android.view.ViewTreeObserver;
 import android.view.ViewTreeObserver.OnGlobalLayoutListener;
 import android.widget.LinearLayout;
 import android.widget.ScrollView;

 import com.android.systemui.R;
 import com.android.systemui.SwipeHelper;
 import com.android.systemui.recent.RecentsPanelView.TaskDescriptionAdapter;

 import java.util.HashSet;
 import java.util.Iterator;

 public class RecentsVerticalScrollView extends ScrollView
         implements SwipeHelper.Callback, RecentsPanelView.RecentsScrollView {
     private static final String TAG = RecentsPanelView.TAG;
     private static final boolean DEBUG = RecentsPanelView.DEBUG;
     private LinearLayout mLinearLayout;
     private TaskDescriptionAdapter mAdapter;
     private RecentsCallback mCallback;
     protected int mLastScrollPosition;
     private SwipeHelper mSwipeHelper;
     private RecentsScrollViewPerformanceHelper mPerformanceHelper;
     private HashSet<View> mRecycledViews;
     private int mNumItemsInOneScreenful;

     public RecentsVerticalScrollView(Context context, AttributeSet attrs) {
         super(context, attrs, 0);
         float densityScale = getResources().getDisplayMetrics().density;
         float pagingTouchSlop = ViewConfiguration.get(mContext).getScaledPagingTouchSlop();
         mSwipeHelper = new SwipeHelper(SwipeHelper.X, this, densityScale, pagingTouchSlop);

         mPerformanceHelper = RecentsScrollViewPerformanceHelper.create(context, attrs, this, true);
         mRecycledViews = new HashSet<View>();
     }

     public void setMinSwipeAlpha(float minAlpha) {
         mSwipeHelper.setMinAlpha(minAlpha);
     }

     private int scrollPositionOfMostRecent() {
         return mLinearLayout.getHeight() - getHeight();
     }

     private void addToRecycledViews(View v) {
         if (mRecycledViews.size() < mNumItemsInOneScreenful) {
             mRecycledViews.add(v);
         }
     }

     public View findViewForTask(int persistentTaskId) {
         for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
             View v = mLinearLayout.getChildAt(i);
             RecentsPanelView.ViewHolder holder = (RecentsPanelView.ViewHolder) v.getTag();
             if (holder.taskDescription.persistentTaskId == persistentTaskId) {
                 return v;
             }
         }
         return null;
     }

     private void update() {
         for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
             View v = mLinearLayout.getChildAt(i);
             addToRecycledViews(v);
             mAdapter.recycleView(v);
         }
         LayoutTransition transitioner = getLayoutTransition();
         setLayoutTransition(null);

         mLinearLayout.removeAllViews();

         // Once we can clear the data associated with individual item views,
         // we can get rid of the removeAllViews() and the code below will
         // recycle them.
         Iterator<View> recycledViews = mRecycledViews.iterator();
         for (int i = 0; i < mAdapter.getCount(); i++) {
             View old = null;
             if (recycledViews.hasNext()) {
                 old = recycledViews.next();
                 recycledViews.remove();
                 old.setVisibility(VISIBLE);
             }
             final View view = mAdapter.getView(i, old, mLinearLayout);

             if (mPerformanceHelper != null) {
                 mPerformanceHelper.addViewCallback(view);
             }

             OnTouchListener noOpListener = new OnTouchListener() {
                 @Override
                 public boolean onTouch(View v, MotionEvent event) {
                     return true;
                 }
             };

             view.setOnClickListener(new OnClickListener() {
                 public void onClick(View v) {
                     mCallback.dismiss();
                 }
             });
             // We don't want a click sound when we dimiss recents
             view.setSoundEffectsEnabled(false);

             OnClickListener launchAppListener = new OnClickListener() {
                 public void onClick(View v) {
                     mCallback.handleOnClick(view);
                 }
             };

             RecentsPanelView.ViewHolder holder = (RecentsPanelView.ViewHolder) view.getTag();
             final View thumbnailView = holder.thumbnailView;
             OnLongClickListener longClickListener = new OnLongClickListener() {
                 public boolean onLongClick(View v) {
                     final View anchorView = view.findViewById(R.id.app_description);
                     mCallback.handleLongPress(view, anchorView, thumbnailView);
                     return true;
                 }
             };
             thumbnailView.setClickable(true);
             thumbnailView.setOnClickListener(launchAppListener);
             thumbnailView.setOnLongClickListener(longClickListener);

             // We don't want to dismiss recents if a user clicks on the app title
             // (we also don't want to launch the app either, though, because the
             // app title is a small target and doesn't have great click feedback)
             final View appTitle = view.findViewById(R.id.app_label);
             appTitle.setContentDescription(" ");
             appTitle.setOnTouchListener(noOpListener);
             final View calloutLine = view.findViewById(R.id.recents_callout_line);
             if (calloutLine != null) {
                 calloutLine.setOnTouchListener(noOpListener);
             }

             mLinearLayout.addView(view);
         }
         setLayoutTransition(transitioner);

         // Scroll to end after initial layout.
         final OnGlobalLayoutListener updateScroll = new OnGlobalLayoutListener() {
                 public void onGlobalLayout() {
                     mLastScrollPosition = scrollPositionOfMostRecent();
                     scrollTo(0, mLastScrollPosition);
                     final ViewTreeObserver observer = getViewTreeObserver();
                     if (observer.isAlive()) {
                         observer.removeOnGlobalLayoutListener(this);
                     }
                 }
             };
         getViewTreeObserver().addOnGlobalLayoutListener(updateScroll);
     }

     @Override
     public void removeViewInLayout(final View view) {
         dismissChild(view);
     }

     public boolean onInterceptTouchEvent(MotionEvent ev) {
         if (DEBUG) Log.v(TAG, "onInterceptTouchEvent()");
         return mSwipeHelper.onInterceptTouchEvent(ev) ||
             super.onInterceptTouchEvent(ev);
     }

     @Override
     public boolean onTouchEvent(MotionEvent ev) {
         return mSwipeHelper.onTouchEvent(ev) ||
             super.onTouchEvent(ev);
     }

     public boolean canChildBeDismissed(View v) {
         return true;
     }

     public void dismissChild(View v) {
         mSwipeHelper.dismissChild(v, 0);
     }

     public void onChildDismissed(View v) {
         addToRecycledViews(v);
         mLinearLayout.removeView(v);
         mCallback.handleSwipe(v);
         // Restore the alpha/translation parameters to what they were before swiping
         // (for when these items are recycled)
         View contentView = getChildContentView(v);
         contentView.setAlpha(1f);
         contentView.setTranslationX(0);
     }

     public void onBeginDrag(View v) {
         // We do this so the underlying ScrollView knows that it won't get
         // the chance to intercept events anymore
         requestDisallowInterceptTouchEvent(true);
     }

     public void onDragCancelled(View v) {
     }

     public View getChildAtPosition(MotionEvent ev) {
         final float x = ev.getX() + getScrollX();
         final float y = ev.getY() + getScrollY();
         for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
             View item = mLinearLayout.getChildAt(i);
             if (item.getVisibility() == View.VISIBLE
                     && x >= item.getLeft() && x < item.getRight()
                     && y >= item.getTop() && y < item.getBottom()) {
                 return item;
             }
         }
         return null;
     }

     public View getChildContentView(View v) {
         return v.findViewById(R.id.recent_item);
     }

     @Override
     public void draw(Canvas canvas) {
         super.draw(canvas);

         if (mPerformanceHelper != null) {
             int paddingLeft = mPaddingLeft;
             final boolean offsetRequired = isPaddingOffsetRequired();
             if (offsetRequired) {
                 paddingLeft += getLeftPaddingOffset();
             }

             int left = mScrollX + paddingLeft;
             int right = left + mRight - mLeft - mPaddingRight - paddingLeft;
             int top = mScrollY + getFadeTop(offsetRequired);
             int bottom = top + getFadeHeight(offsetRequired);

             if (offsetRequired) {
                 right += getRightPaddingOffset();
                 bottom += getBottomPaddingOffset();
             }
             mPerformanceHelper.drawCallback(canvas,
                     left, right, top, bottom, mScrollX, mScrollY,
                     getTopFadingEdgeStrength(), getBottomFadingEdgeStrength(),
                     0, 0);
         }
     }

     @Override
     public int getVerticalFadingEdgeLength() {
         if (mPerformanceHelper != null) {
             return mPerformanceHelper.getVerticalFadingEdgeLengthCallback();
         } else {
             return super.getVerticalFadingEdgeLength();
         }
     }

     @Override
     public int getHorizontalFadingEdgeLength() {
         if (mPerformanceHelper != null) {
             return mPerformanceHelper.getHorizontalFadingEdgeLengthCallback();
         } else {
             return super.getHorizontalFadingEdgeLength();
         }
     }

     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
         setScrollbarFadingEnabled(true);
         mLinearLayout = (LinearLayout) findViewById(R.id.recents_linear_layout);
         final int leftPadding = mContext.getResources()
             .getDimensionPixelOffset(R.dimen.status_bar_recents_thumbnail_left_margin);
         setOverScrollEffectPadding(leftPadding, 0);
     }

     @Override
     public void onAttachedToWindow() {
         if (mPerformanceHelper != null) {
             mPerformanceHelper.onAttachedToWindowCallback(
                     mCallback, mLinearLayout, isHardwareAccelerated());
         }
     }

     @Override
     protected void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
         float densityScale = getResources().getDisplayMetrics().density;
         mSwipeHelper.setDensityScale(densityScale);
         float pagingTouchSlop = ViewConfiguration.get(mContext).getScaledPagingTouchSlop();
         mSwipeHelper.setPagingTouchSlop(pagingTouchSlop);
     }

     private void setOverScrollEffectPadding(int leftPadding, int i) {
         // TODO Add to (Vertical)ScrollView
     }

     @Override
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
         super.onSizeChanged(w, h, oldw, oldh);

         // Skip this work if a transition is running; it sets the scroll values independently
         // and should not have those animated values clobbered by this logic
         LayoutTransition transition = mLinearLayout.getLayoutTransition();
         if (transition != null && transition.isRunning()) {
             return;
         }
         // Keep track of the last visible item in the list so we can restore it
         // to the bottom when the orientation changes.
         mLastScrollPosition = scrollPositionOfMostRecent();

         // This has to happen post-layout, so run it "in the future"
         post(new Runnable() {
             public void run() {
                 // Make sure we're still not clobbering the transition-set values, since this
                 // runnable launches asynchronously
                 LayoutTransition transition = mLinearLayout.getLayoutTransition();
                 if (transition == null || !transition.isRunning()) {
                     scrollTo(0, mLastScrollPosition);
                 }
             }
         });
     }

     public void setAdapter(TaskDescriptionAdapter adapter) {
         mAdapter = adapter;
         mAdapter.registerDataSetObserver(new DataSetObserver() {
             public void onChanged() {
                 update();
             }

             public void onInvalidated() {
                 update();
             }
         });

         DisplayMetrics dm = getResources().getDisplayMetrics();
         int childWidthMeasureSpec =
                 MeasureSpec.makeMeasureSpec(dm.widthPixels, MeasureSpec.AT_MOST);
         int childheightMeasureSpec =
                 MeasureSpec.makeMeasureSpec(dm.heightPixels, MeasureSpec.AT_MOST);
         View child = mAdapter.createView(mLinearLayout);
         child.measure(childWidthMeasureSpec, childheightMeasureSpec);
         mNumItemsInOneScreenful =
                 (int) FloatMath.ceil(dm.heightPixels / (float) child.getMeasuredHeight());
         addToRecycledViews(child);

         for (int i = 0; i < mNumItemsInOneScreenful - 1; i++) {
             addToRecycledViews(mAdapter.createView(mLinearLayout));
         }
     }

     public int numItemsInOneScreenful() {
         return mNumItemsInOneScreenful;
     }

     @Override
     public void setLayoutTransition(LayoutTransition transition) {
         // The layout transition applies to our embedded LinearLayout
         mLinearLayout.setLayoutTransition(transition);
     }

     public void setCallback(RecentsCallback callback) {
         mCallback = callback;
     }
 }
	/*
	* Copyright (C) 2011 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.android.systemui.recent;

	import android.animation.LayoutTransition;
	import android.content.Context;
	import android.content.res.Configuration;
	import android.database.DataSetObserver;
	import android.graphics.Canvas;
	import android.util.AttributeSet;
	import android.util.DisplayMetrics;
	import android.util.FloatMath;
	import android.util.Log;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.ViewConfiguration;
	import android.view.ViewTreeObserver;
	import android.view.ViewTreeObserver.OnGlobalLayoutListener;
	import android.widget.LinearLayout;
	import android.widget.ScrollView;

	import com.android.systemui.R;
	import com.android.systemui.SwipeHelper;
	import com.android.systemui.recent.RecentsPanelView.TaskDescriptionAdapter;

	import java.util.HashSet;
	import java.util.Iterator;

	public class RecentsVerticalScrollView extends ScrollView
	implements SwipeHelper.Callback, RecentsPanelView.RecentsScrollView {
	private static final String TAG = RecentsPanelView.TAG;
	private static final boolean DEBUG = RecentsPanelView.DEBUG;
	private LinearLayout mLinearLayout;
	private TaskDescriptionAdapter mAdapter;
	private RecentsCallback mCallback;
	protected int mLastScrollPosition;
	private SwipeHelper mSwipeHelper;
	private RecentsScrollViewPerformanceHelper mPerformanceHelper;
	private HashSet<View> mRecycledViews;
	private int mNumItemsInOneScreenful;

	public RecentsVerticalScrollView(Context context, AttributeSet attrs) {
	super(context, attrs, 0);
	float densityScale = getResources().getDisplayMetrics().density;
	float pagingTouchSlop = ViewConfiguration.get(mContext).getScaledPagingTouchSlop();
	mSwipeHelper = new SwipeHelper(SwipeHelper.X, this, densityScale, pagingTouchSlop);

	mPerformanceHelper = RecentsScrollViewPerformanceHelper.create(context, attrs, this, true);
	mRecycledViews = new HashSet<View>();
	}

	public void setMinSwipeAlpha(float minAlpha) {
	mSwipeHelper.setMinAlpha(minAlpha);
	}

	private int scrollPositionOfMostRecent() {
	return mLinearLayout.getHeight() - getHeight();
	}

	private void addToRecycledViews(View v) {
	if (mRecycledViews.size() < mNumItemsInOneScreenful) {
	mRecycledViews.add(v);
	}
	}

	public View findViewForTask(int persistentTaskId) {
	for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
	View v = mLinearLayout.getChildAt(i);
	RecentsPanelView.ViewHolder holder = (RecentsPanelView.ViewHolder) v.getTag();
	if (holder.taskDescription.persistentTaskId == persistentTaskId) {
	return v;
	}
	}
	return null;
	}

	private void update() {
	for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
	View v = mLinearLayout.getChildAt(i);
	addToRecycledViews(v);
	mAdapter.recycleView(v);
	}
	LayoutTransition transitioner = getLayoutTransition();
	setLayoutTransition(null);

	mLinearLayout.removeAllViews();

	// Once we can clear the data associated with individual item views,
	// we can get rid of the removeAllViews() and the code below will
	// recycle them.
	Iterator<View> recycledViews = mRecycledViews.iterator();
	for (int i = 0; i < mAdapter.getCount(); i++) {
	View old = null;
	if (recycledViews.hasNext()) {
	old = recycledViews.next();
	recycledViews.remove();
	old.setVisibility(VISIBLE);
	}
	final View view = mAdapter.getView(i, old, mLinearLayout);

	if (mPerformanceHelper != null) {
	mPerformanceHelper.addViewCallback(view);
	}

	OnTouchListener noOpListener = new OnTouchListener() {
	@Override
	public boolean onTouch(View v, MotionEvent event) {
	return true;
	}
	};

	view.setOnClickListener(new OnClickListener() {
	public void onClick(View v) {
	mCallback.dismiss();
	}
	});
	// We don't want a click sound when we dimiss recents
	view.setSoundEffectsEnabled(false);

	OnClickListener launchAppListener = new OnClickListener() {
	public void onClick(View v) {
	mCallback.handleOnClick(view);
	}
	};

	RecentsPanelView.ViewHolder holder = (RecentsPanelView.ViewHolder) view.getTag();
	final View thumbnailView = holder.thumbnailView;
	OnLongClickListener longClickListener = new OnLongClickListener() {
	public boolean onLongClick(View v) {
	final View anchorView = view.findViewById(R.id.app_description);
	mCallback.handleLongPress(view, anchorView, thumbnailView);
	return true;
	}
	};
	thumbnailView.setClickable(true);
	thumbnailView.setOnClickListener(launchAppListener);
	thumbnailView.setOnLongClickListener(longClickListener);

	// We don't want to dismiss recents if a user clicks on the app title
	// (we also don't want to launch the app either, though, because the
	// app title is a small target and doesn't have great click feedback)
	final View appTitle = view.findViewById(R.id.app_label);
	appTitle.setContentDescription(" ");
	appTitle.setOnTouchListener(noOpListener);
	final View calloutLine = view.findViewById(R.id.recents_callout_line);
	if (calloutLine != null) {
	calloutLine.setOnTouchListener(noOpListener);
	}

	mLinearLayout.addView(view);
	}
	setLayoutTransition(transitioner);

	// Scroll to end after initial layout.
	final OnGlobalLayoutListener updateScroll = new OnGlobalLayoutListener() {
	public void onGlobalLayout() {
	mLastScrollPosition = scrollPositionOfMostRecent();
	scrollTo(0, mLastScrollPosition);
	final ViewTreeObserver observer = getViewTreeObserver();
	if (observer.isAlive()) {
	observer.removeOnGlobalLayoutListener(this);
	}
	}
	};
	getViewTreeObserver().addOnGlobalLayoutListener(updateScroll);
	}

	@Override
	public void removeViewInLayout(final View view) {
	dismissChild(view);
	}

	public boolean onInterceptTouchEvent(MotionEvent ev) {
	if (DEBUG) Log.v(TAG, "onInterceptTouchEvent()");
	return mSwipeHelper.onInterceptTouchEvent(ev) \|\|
	super.onInterceptTouchEvent(ev);
	}

	@Override
	public boolean onTouchEvent(MotionEvent ev) {
	return mSwipeHelper.onTouchEvent(ev) \|\|
	super.onTouchEvent(ev);
	}

	public boolean canChildBeDismissed(View v) {
	return true;
	}

	public void dismissChild(View v) {
	mSwipeHelper.dismissChild(v, 0);
	}

	public void onChildDismissed(View v) {
	addToRecycledViews(v);
	mLinearLayout.removeView(v);
	mCallback.handleSwipe(v);
	// Restore the alpha/translation parameters to what they were before swiping
	// (for when these items are recycled)
	View contentView = getChildContentView(v);
	contentView.setAlpha(1f);
	contentView.setTranslationX(0);
	}

	public void onBeginDrag(View v) {
	// We do this so the underlying ScrollView knows that it won't get
	// the chance to intercept events anymore
	requestDisallowInterceptTouchEvent(true);
	}

	public void onDragCancelled(View v) {
	}

	public View getChildAtPosition(MotionEvent ev) {
	final float x = ev.getX() + getScrollX();
	final float y = ev.getY() + getScrollY();
	for (int i = 0; i < mLinearLayout.getChildCount(); i++) {
	View item = mLinearLayout.getChildAt(i);
	if (item.getVisibility() == View.VISIBLE
	&& x >= item.getLeft() && x < item.getRight()
	&& y >= item.getTop() && y < item.getBottom()) {
	return item;
	}
	}
	return null;
	}

	public View getChildContentView(View v) {
	return v.findViewById(R.id.recent_item);
	}

	@Override
	public void draw(Canvas canvas) {
	super.draw(canvas);

	if (mPerformanceHelper != null) {
	int paddingLeft = mPaddingLeft;
	final boolean offsetRequired = isPaddingOffsetRequired();
	if (offsetRequired) {
	paddingLeft += getLeftPaddingOffset();
	}

	int left = mScrollX + paddingLeft;
	int right = left + mRight - mLeft - mPaddingRight - paddingLeft;
	int top = mScrollY + getFadeTop(offsetRequired);
	int bottom = top + getFadeHeight(offsetRequired);

	if (offsetRequired) {
	right += getRightPaddingOffset();
	bottom += getBottomPaddingOffset();
	}
	mPerformanceHelper.drawCallback(canvas,
	left, right, top, bottom, mScrollX, mScrollY,
	getTopFadingEdgeStrength(), getBottomFadingEdgeStrength(),
	0, 0);
	}
	}

	@Override
	public int getVerticalFadingEdgeLength() {
	if (mPerformanceHelper != null) {
	return mPerformanceHelper.getVerticalFadingEdgeLengthCallback();
	} else {
	return super.getVerticalFadingEdgeLength();
	}
	}

	@Override
	public int getHorizontalFadingEdgeLength() {
	if (mPerformanceHelper != null) {
	return mPerformanceHelper.getHorizontalFadingEdgeLengthCallback();
	} else {
	return super.getHorizontalFadingEdgeLength();
	}
	}

	@Override
	protected void onFinishInflate() {
	super.onFinishInflate();
	setScrollbarFadingEnabled(true);
	mLinearLayout = (LinearLayout) findViewById(R.id.recents_linear_layout);
	final int leftPadding = mContext.getResources()
	.getDimensionPixelOffset(R.dimen.status_bar_recents_thumbnail_left_margin);
	setOverScrollEffectPadding(leftPadding, 0);
	}

	@Override
	public void onAttachedToWindow() {
	if (mPerformanceHelper != null) {
	mPerformanceHelper.onAttachedToWindowCallback(
	mCallback, mLinearLayout, isHardwareAccelerated());
	}
	}

	@Override
	protected void onConfigurationChanged(Configuration newConfig) {
	super.onConfigurationChanged(newConfig);
	float densityScale = getResources().getDisplayMetrics().density;
	mSwipeHelper.setDensityScale(densityScale);
	float pagingTouchSlop = ViewConfiguration.get(mContext).getScaledPagingTouchSlop();
	mSwipeHelper.setPagingTouchSlop(pagingTouchSlop);
	}

	private void setOverScrollEffectPadding(int leftPadding, int i) {
	// TODO Add to (Vertical)ScrollView
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
	super.onSizeChanged(w, h, oldw, oldh);

	// Skip this work if a transition is running; it sets the scroll values independently
	// and should not have those animated values clobbered by this logic
	LayoutTransition transition = mLinearLayout.getLayoutTransition();
	if (transition != null && transition.isRunning()) {
	return;
	}
	// Keep track of the last visible item in the list so we can restore it
	// to the bottom when the orientation changes.
	mLastScrollPosition = scrollPositionOfMostRecent();

	// This has to happen post-layout, so run it "in the future"
	post(new Runnable() {
	public void run() {
	// Make sure we're still not clobbering the transition-set values, since this
	// runnable launches asynchronously
	LayoutTransition transition = mLinearLayout.getLayoutTransition();
	if (transition == null \|\| !transition.isRunning()) {
	scrollTo(0, mLastScrollPosition);
	}
	}
	});
	}

	public void setAdapter(TaskDescriptionAdapter adapter) {
	mAdapter = adapter;
	mAdapter.registerDataSetObserver(new DataSetObserver() {
	public void onChanged() {
	update();
	}

	public void onInvalidated() {
	update();
	}
	});

	DisplayMetrics dm = getResources().getDisplayMetrics();
	int childWidthMeasureSpec =
	MeasureSpec.makeMeasureSpec(dm.widthPixels, MeasureSpec.AT_MOST);
	int childheightMeasureSpec =
	MeasureSpec.makeMeasureSpec(dm.heightPixels, MeasureSpec.AT_MOST);
	View child = mAdapter.createView(mLinearLayout);
	child.measure(childWidthMeasureSpec, childheightMeasureSpec);
	mNumItemsInOneScreenful =
	(int) FloatMath.ceil(dm.heightPixels / (float) child.getMeasuredHeight());
	addToRecycledViews(child);

	for (int i = 0; i < mNumItemsInOneScreenful - 1; i++) {
	addToRecycledViews(mAdapter.createView(mLinearLayout));
	}
	}

	public int numItemsInOneScreenful() {
	return mNumItemsInOneScreenful;
	}

	@Override
	public void setLayoutTransition(LayoutTransition transition) {
	// The layout transition applies to our embedded LinearLayout
	mLinearLayout.setLayoutTransition(transition);
	}

	public void setCallback(RecentsCallback callback) {
	mCallback = callback;
	}
	}