prebuilts/gradle/BatchStepSensor/Application/src/main/java/com/example/android/batchstepsensor/cardstream/CardStreamLinearLayout.java - platform/developers/build - Gitiles

 /*
 * Copyright 2013 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.example.android.batchstepsensor.cardstream;

 import android.animation.Animator;
 import android.animation.LayoutTransition;
 import android.animation.ObjectAnimator;
 import android.annotation.SuppressLint;
 import android.annotation.TargetApi;
 import android.content.Context;
 import android.content.res.TypedArray;
 import android.graphics.Rect;
 import android.os.Build;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewConfiguration;
 import android.view.ViewGroup;
 import android.view.ViewParent;
 import android.widget.LinearLayout;
 import android.widget.ScrollView;

 import com.example.android.common.logger.Log;
 import com.example.android.batchstepsensor.R;

 import java.util.ArrayList;

 /**
  * A Layout that contains a stream of card views.
  */
 public class CardStreamLinearLayout extends LinearLayout {

     public static final int ANIMATION_SPEED_SLOW = 1001;
     public static final int ANIMATION_SPEED_NORMAL = 1002;
     public static final int ANIMATION_SPEED_FAST = 1003;

     private static final String TAG = "CardStreamLinearLayout";
     private final ArrayList<View> mFixedViewList = new ArrayList<View>();
     private final Rect mChildRect = new Rect();
     private CardStreamAnimator mAnimators;
     private OnDissmissListener mDismissListener = null;
     private boolean mLayouted = false;
     private boolean mSwiping = false;
     private String mFirstVisibleCardTag = null;
     private boolean mShowInitialAnimation = false;

     /**
      * Handle touch events to fade/move dragged items as they are swiped out
      */
     private OnTouchListener mTouchListener = new OnTouchListener() {

         private float mDownX;
         private float mDownY;

         @Override
         public boolean onTouch(final View v, MotionEvent event) {

             switch (event.getAction()) {
                 case MotionEvent.ACTION_DOWN:
                     mDownX = event.getX();
                     mDownY = event.getY();
                     break;
                 case MotionEvent.ACTION_CANCEL:
                     resetAnimatedView(v);
                     mSwiping = false;
                     mDownX = 0.f;
                     mDownY = 0.f;
                     break;
                 case MotionEvent.ACTION_MOVE: {

                     float x = event.getX() + v.getTranslationX();
                     float y = event.getY() + v.getTranslationY();

                     mDownX = mDownX == 0.f ? x : mDownX;
                     mDownY = mDownY == 0.f ? x : mDownY;

                     float deltaX = x - mDownX;
                     float deltaY = y - mDownY;

                     if (!mSwiping && isSwiping(deltaX, deltaY)) {
                         mSwiping = true;
                         v.getParent().requestDisallowInterceptTouchEvent(true);
                     } else {
                         swipeView(v, deltaX, deltaY);
                     }
                 }
                 break;
                 case MotionEvent.ACTION_UP: {
                     // User let go - figure out whether to animate the view out, or back into place
                     if (mSwiping) {
                         float x = event.getX() + v.getTranslationX();
                         float y = event.getY() + v.getTranslationY();

                         float deltaX = x - mDownX;
                         float deltaY = y - mDownX;
                         float deltaXAbs = Math.abs(deltaX);

                         // User let go - figure out whether to animate the view out, or back into place
                         boolean remove = deltaXAbs > v.getWidth() / 4 && !isFixedView(v);
                         if( remove )
                             handleViewSwipingOut(v, deltaX, deltaY);
                         else
                             handleViewSwipingIn(v, deltaX, deltaY);
                     }
                     mDownX = 0.f;
                     mDownY = 0.f;
                     mSwiping = false;
                 }
                 break;
                 default:
                     return false;
             }
             return false;
         }
     };
     private int mSwipeSlop = -1;
     /**
      * Handle end-transition animation event of each child and launch a following animation.
      */
     private LayoutTransition.TransitionListener mTransitionListener
             = new LayoutTransition.TransitionListener() {

         @Override
         public void startTransition(LayoutTransition transition, ViewGroup container, View
                 view, int transitionType) {
             Log.d(TAG, "Start LayoutTransition animation:" + transitionType);
         }

         @Override
         public void endTransition(LayoutTransition transition, ViewGroup container,
                                   final View view, int transitionType) {

             Log.d(TAG, "End LayoutTransition animation:" + transitionType);
             if (transitionType == LayoutTransition.APPEARING) {
                 final View area = view.findViewById(R.id.card_actionarea);
                 if (area != null) {
                     runShowActionAreaAnimation(container, area);
                 }
             }
         }
     };
     /**
      * Handle a hierarchy change event
      * when a new child is added, scroll to bottom and hide action area..
      */
     private OnHierarchyChangeListener mOnHierarchyChangeListener
             = new OnHierarchyChangeListener() {
         @Override
         public void onChildViewAdded(final View parent, final View child) {

             Log.d(TAG, "child is added: " + child);

             ViewParent scrollView = parent.getParent();
             if (scrollView != null && scrollView instanceof ScrollView) {
                 ((ScrollView) scrollView).fullScroll(FOCUS_DOWN);
             }

             if (getLayoutTransition() != null) {
                 View view = child.findViewById(R.id.card_actionarea);
                 if (view != null)
                     view.setAlpha(0.f);
             }
         }

         @Override
         public void onChildViewRemoved(View parent, View child) {
             Log.d(TAG, "child is removed: " + child);
             mFixedViewList.remove(child);
         }
     };
     private int mLastDownX;

     public CardStreamLinearLayout(Context context) {
         super(context);
         initialize(null, 0);
     }

     public CardStreamLinearLayout(Context context, AttributeSet attrs) {
         super(context, attrs);
         initialize(attrs, 0);
     }

     @SuppressLint("NewApi")
     public CardStreamLinearLayout(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
         initialize(attrs, defStyle);
     }

     /**
      * add a card view w/ canDismiss flag.
      *
      * @param cardView   a card view
      * @param canDismiss flag to indicate this card is dismissible or not.
      */
     public void addCard(View cardView, boolean canDismiss) {
         if (cardView.getParent() == null) {
             initCard(cardView, canDismiss);

             ViewGroup.LayoutParams param = cardView.getLayoutParams();
             if(param == null)
                 param = generateDefaultLayoutParams();

             super.addView(cardView, -1, param);
         }
     }

     @Override
     public void addView(View child, int index, ViewGroup.LayoutParams params) {
         if (child.getParent() == null) {
             initCard(child, true);
             super.addView(child, index, params);
         }
     }

     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     @Override
     protected void onLayout(boolean changed, int l, int t, int r, int b) {
         super.onLayout(changed, l, t, r, b);
         Log.d(TAG, "onLayout: " + changed);

         if( changed && !mLayouted ){
             mLayouted = true;

             ObjectAnimator animator;
             LayoutTransition layoutTransition = new LayoutTransition();

             animator = mAnimators.getDisappearingAnimator(getContext());
             layoutTransition.setAnimator(LayoutTransition.DISAPPEARING, animator);

             animator = mAnimators.getAppearingAnimator(getContext());
             layoutTransition.setAnimator(LayoutTransition.APPEARING, animator);

             layoutTransition.addTransitionListener(mTransitionListener);

             if( animator != null )
                 layoutTransition.setDuration(animator.getDuration());

             setLayoutTransition(layoutTransition);

             if( mShowInitialAnimation )
                 runInitialAnimations();

             if (mFirstVisibleCardTag != null) {
                 scrollToCard(mFirstVisibleCardTag);
                 mFirstVisibleCardTag = null;
             }
         }
     }

     /**
      * Check whether a user moved enough distance to start a swipe action or not.
      *
      * @param deltaX
      * @param deltaY
      * @return true if a user is swiping.
      */
     protected boolean isSwiping(float deltaX, float deltaY) {

         if (mSwipeSlop < 0) {
             //get swipping slop from ViewConfiguration;
             mSwipeSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
         }

         boolean swipping = false;
         float absDeltaX = Math.abs(deltaX);

         if( absDeltaX > mSwipeSlop )
             return true;

         return swipping;
     }

     /**
      * Swipe a view by moving distance
      *
      * @param child a target view
      * @param deltaX x moving distance by x-axis.
      * @param deltaY y moving distance by y-axis.
      */
     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     protected void swipeView(View child, float deltaX, float deltaY) {
         if (isFixedView(child)){
             deltaX = deltaX / 4;
         }

         float deltaXAbs = Math.abs(deltaX);
         float fractionCovered = deltaXAbs / (float) child.getWidth();

         child.setTranslationX(deltaX);
         child.setAlpha(1.f - fractionCovered);

         if (deltaX > 0)
             child.setRotationY(-15.f * fractionCovered);
         else
             child.setRotationY(15.f * fractionCovered);
     }

     protected void notifyOnDismissEvent( View child ){
         if( child == null || mDismissListener == null )
             return;

         mDismissListener.onDismiss((String) child.getTag());
     }

     /**
      * get the tag of the first visible child in this layout
      *
      * @return tag of the first visible child or null
      */
     public String getFirstVisibleCardTag() {

         final int count = getChildCount();

         if (count == 0)
             return null;

         for (int index = 0; index < count; ++index) {
             //check the position of each view.
             View child = getChildAt(index);
             if (child.getGlobalVisibleRect(mChildRect) == true)
                 return (String) child.getTag();
         }

         return null;
     }

     /**
      * Set the first visible card of this linear layout.
      *
      * @param tag tag of a card which should already added to this layout.
      */
     public void setFirstVisibleCard(String tag) {
         if (tag == null)
             return; //do nothing.

         if (mLayouted) {
             scrollToCard(tag);
         } else {
             //keep the tag for next use.
             mFirstVisibleCardTag = tag;
         }
     }

     /**
      * If this flag is set,
      * after finishing initial onLayout event, an initial animation which is defined in DefaultCardStreamAnimator is launched.
      */
     public void triggerShowInitialAnimation(){
         mShowInitialAnimation = true;
     }

     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     public void setCardStreamAnimator( CardStreamAnimator animators ){

         if( animators == null )
             mAnimators = new CardStreamAnimator.EmptyAnimator();
         else
             mAnimators = animators;

         LayoutTransition layoutTransition = getLayoutTransition();

         if( layoutTransition != null ){
             layoutTransition.setAnimator( LayoutTransition.APPEARING,
                     mAnimators.getAppearingAnimator(getContext()) );
             layoutTransition.setAnimator( LayoutTransition.DISAPPEARING,
                     mAnimators.getDisappearingAnimator(getContext()) );
         }
     }

     /**
      * set a OnDismissListener which called when user dismiss a card.
      *
      * @param listener
      */
     public void setOnDismissListener(OnDissmissListener listener) {
         mDismissListener = listener;
     }

     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     private void initialize(AttributeSet attrs, int defStyle) {

         float speedFactor = 1.f;

         if (attrs != null) {
             TypedArray a = getContext().obtainStyledAttributes(attrs,
                     R.styleable.CardStream, defStyle, 0);

             if( a != null ){
                 int speedType = a.getInt(R.styleable.CardStream_animationDuration, 1001);
                 switch (speedType){
                     case ANIMATION_SPEED_FAST:
                         speedFactor = 0.5f;
                         break;
                     case ANIMATION_SPEED_NORMAL:
                         speedFactor = 1.f;
                         break;
                     case ANIMATION_SPEED_SLOW:
                         speedFactor = 2.f;
                         break;
                 }

                 String animatorName = a.getString(R.styleable.CardStream_animators);

                 try {
                     if( animatorName != null )
                         mAnimators = (CardStreamAnimator) getClass().getClassLoader()
                                 .loadClass(animatorName).newInstance();
                 } catch (Exception e) {
                     Log.e(TAG, "Fail to load animator:" + animatorName, e);
                 } finally {
                     if(mAnimators == null)
                         mAnimators = new DefaultCardStreamAnimator();
                 }
                 a.recycle();
             }
         }

         mAnimators.setSpeedFactor(speedFactor);
         mSwipeSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
         setOnHierarchyChangeListener(mOnHierarchyChangeListener);
     }

     private void initCard(View cardView, boolean canDismiss) {
         resetAnimatedView(cardView);
         cardView.setOnTouchListener(mTouchListener);
         if (!canDismiss)
             mFixedViewList.add(cardView);
     }

     private boolean isFixedView(View v) {
         return mFixedViewList.contains(v);
     }

     private void resetAnimatedView(View child) {
         child.setAlpha(1.f);
         child.setTranslationX(0.f);
         child.setTranslationY(0.f);
         child.setRotation(0.f);
         child.setRotationY(0.f);
         child.setRotationX(0.f);
         child.setScaleX(1.f);
         child.setScaleY(1.f);
     }

     @TargetApi(Build.VERSION_CODES.HONEYCOMB)
     private void runInitialAnimations() {
         if( mAnimators == null )
             return;

         final int count = getChildCount();

         for (int index = 0; index < count; ++index) {
             final View child = getChildAt(index);
             ObjectAnimator animator =  mAnimators.getInitalAnimator(getContext());
             if( animator != null ){
                 animator.setTarget(child);
                 animator.start();
             }
         }
     }

     private void runShowActionAreaAnimation(View parent, View area) {
         area.setPivotY(0.f);
         area.setPivotX(parent.getWidth() / 2.f);

         area.setAlpha(0.5f);
         area.setRotationX(-90.f);
         area.animate().rotationX(0.f).alpha(1.f).setDuration(400);
     }

     private void handleViewSwipingOut(final View child, float deltaX, float deltaY) {
         ObjectAnimator animator = mAnimators.getSwipeOutAnimator(child, deltaX, deltaY);
         if( animator != null ){
             animator.addListener(new EndAnimationWrapper() {
                 @Override
                 public void onAnimationEnd(Animator animation) {
                     removeView(child);
                     notifyOnDismissEvent(child);
                 }
             });
         } else {
             removeView(child);
             notifyOnDismissEvent(child);
         }

         if( animator != null ){
             animator.setTarget(child);
             animator.start();
         }
     }

     private void handleViewSwipingIn(final View child, float deltaX, float deltaY) {
         ObjectAnimator animator = mAnimators.getSwipeInAnimator(child, deltaX, deltaY);
         if( animator != null ){
             animator.addListener(new EndAnimationWrapper() {
                 @Override
                 public void onAnimationEnd(Animator animation) {
                     child.setTranslationY(0.f);
                     child.setTranslationX(0.f);
                 }
             });
         } else {
             child.setTranslationY(0.f);
             child.setTranslationX(0.f);
         }

         if( animator != null ){
             animator.setTarget(child);
             animator.start();
         }
     }

     private void scrollToCard(String tag) {


         final int count = getChildCount();
         for (int index = 0; index < count; ++index) {
             View child = getChildAt(index);

             if (tag.equals(child.getTag())) {

                 ViewParent parent = getParent();
                 if( parent != null && parent instanceof ScrollView ){
                     ((ScrollView)parent).smoothScrollTo(
                             0, child.getTop() - getPaddingTop() - child.getPaddingTop());
                 }
                 return;
             }
         }
     }

     public interface OnDissmissListener {
         public void onDismiss(String tag);
     }

     /**
      * Empty default AnimationListener
      */
     private abstract class EndAnimationWrapper implements Animator.AnimatorListener {

         @Override
         public void onAnimationStart(Animator animation) {
         }

         @Override
         public void onAnimationCancel(Animator animation) {
         }

         @Override
         public void onAnimationRepeat(Animator animation) {
         }
     }//end of inner class
 }
	/*
	* Copyright 2013 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.example.android.batchstepsensor.cardstream;

	import android.animation.Animator;
	import android.animation.LayoutTransition;
	import android.animation.ObjectAnimator;
	import android.annotation.SuppressLint;
	import android.annotation.TargetApi;
	import android.content.Context;
	import android.content.res.TypedArray;
	import android.graphics.Rect;
	import android.os.Build;
	import android.util.AttributeSet;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.ViewConfiguration;
	import android.view.ViewGroup;
	import android.view.ViewParent;
	import android.widget.LinearLayout;
	import android.widget.ScrollView;

	import com.example.android.common.logger.Log;
	import com.example.android.batchstepsensor.R;

	import java.util.ArrayList;

	/**
	* A Layout that contains a stream of card views.
	*/
	public class CardStreamLinearLayout extends LinearLayout {

	public static final int ANIMATION_SPEED_SLOW = 1001;
	public static final int ANIMATION_SPEED_NORMAL = 1002;
	public static final int ANIMATION_SPEED_FAST = 1003;

	private static final String TAG = "CardStreamLinearLayout";
	private final ArrayList<View> mFixedViewList = new ArrayList<View>();
	private final Rect mChildRect = new Rect();
	private CardStreamAnimator mAnimators;
	private OnDissmissListener mDismissListener = null;
	private boolean mLayouted = false;
	private boolean mSwiping = false;
	private String mFirstVisibleCardTag = null;
	private boolean mShowInitialAnimation = false;

	/**
	* Handle touch events to fade/move dragged items as they are swiped out
	*/
	private OnTouchListener mTouchListener = new OnTouchListener() {

	private float mDownX;
	private float mDownY;

	@Override
	public boolean onTouch(final View v, MotionEvent event) {

	switch (event.getAction()) {
	case MotionEvent.ACTION_DOWN:
	mDownX = event.getX();
	mDownY = event.getY();
	break;
	case MotionEvent.ACTION_CANCEL:
	resetAnimatedView(v);
	mSwiping = false;
	mDownX = 0.f;
	mDownY = 0.f;
	break;
	case MotionEvent.ACTION_MOVE: {

	float x = event.getX() + v.getTranslationX();
	float y = event.getY() + v.getTranslationY();

	mDownX = mDownX == 0.f ? x : mDownX;
	mDownY = mDownY == 0.f ? x : mDownY;

	float deltaX = x - mDownX;
	float deltaY = y - mDownY;

	if (!mSwiping && isSwiping(deltaX, deltaY)) {
	mSwiping = true;
	v.getParent().requestDisallowInterceptTouchEvent(true);
	} else {
	swipeView(v, deltaX, deltaY);
	}
	}
	break;
	case MotionEvent.ACTION_UP: {
	// User let go - figure out whether to animate the view out, or back into place
	if (mSwiping) {
	float x = event.getX() + v.getTranslationX();
	float y = event.getY() + v.getTranslationY();

	float deltaX = x - mDownX;
	float deltaY = y - mDownX;
	float deltaXAbs = Math.abs(deltaX);

	// User let go - figure out whether to animate the view out, or back into place
	boolean remove = deltaXAbs > v.getWidth() / 4 && !isFixedView(v);
	if( remove )
	handleViewSwipingOut(v, deltaX, deltaY);
	else
	handleViewSwipingIn(v, deltaX, deltaY);
	}
	mDownX = 0.f;
	mDownY = 0.f;
	mSwiping = false;
	}
	break;
	default:
	return false;
	}
	return false;
	}
	};
	private int mSwipeSlop = -1;
	/**
	* Handle end-transition animation event of each child and launch a following animation.
	*/
	private LayoutTransition.TransitionListener mTransitionListener
	= new LayoutTransition.TransitionListener() {

	@Override
	public void startTransition(LayoutTransition transition, ViewGroup container, View
	view, int transitionType) {
	Log.d(TAG, "Start LayoutTransition animation:" + transitionType);
	}

	@Override
	public void endTransition(LayoutTransition transition, ViewGroup container,
	final View view, int transitionType) {

	Log.d(TAG, "End LayoutTransition animation:" + transitionType);
	if (transitionType == LayoutTransition.APPEARING) {
	final View area = view.findViewById(R.id.card_actionarea);
	if (area != null) {
	runShowActionAreaAnimation(container, area);
	}
	}
	}
	};
	/**
	* Handle a hierarchy change event
	* when a new child is added, scroll to bottom and hide action area..
	*/
	private OnHierarchyChangeListener mOnHierarchyChangeListener
	= new OnHierarchyChangeListener() {
	@Override
	public void onChildViewAdded(final View parent, final View child) {

	Log.d(TAG, "child is added: " + child);

	ViewParent scrollView = parent.getParent();
	if (scrollView != null && scrollView instanceof ScrollView) {
	((ScrollView) scrollView).fullScroll(FOCUS_DOWN);
	}

	if (getLayoutTransition() != null) {
	View view = child.findViewById(R.id.card_actionarea);
	if (view != null)
	view.setAlpha(0.f);
	}
	}

	@Override
	public void onChildViewRemoved(View parent, View child) {
	Log.d(TAG, "child is removed: " + child);
	mFixedViewList.remove(child);
	}
	};
	private int mLastDownX;

	public CardStreamLinearLayout(Context context) {
	super(context);
	initialize(null, 0);
	}

	public CardStreamLinearLayout(Context context, AttributeSet attrs) {
	super(context, attrs);
	initialize(attrs, 0);
	}

	@SuppressLint("NewApi")
	public CardStreamLinearLayout(Context context, AttributeSet attrs, int defStyle) {
	super(context, attrs, defStyle);
	initialize(attrs, defStyle);
	}

	/**
	* add a card view w/ canDismiss flag.
	*
	* @param cardView a card view
	* @param canDismiss flag to indicate this card is dismissible or not.
	*/
	public void addCard(View cardView, boolean canDismiss) {
	if (cardView.getParent() == null) {
	initCard(cardView, canDismiss);

	ViewGroup.LayoutParams param = cardView.getLayoutParams();
	if(param == null)
	param = generateDefaultLayoutParams();

	super.addView(cardView, -1, param);
	}
	}

	@Override
	public void addView(View child, int index, ViewGroup.LayoutParams params) {
	if (child.getParent() == null) {
	initCard(child, true);
	super.addView(child, index, params);
	}
	}

	@TargetApi(Build.VERSION_CODES.HONEYCOMB)
	@Override
	protected void onLayout(boolean changed, int l, int t, int r, int b) {
	super.onLayout(changed, l, t, r, b);
	Log.d(TAG, "onLayout: " + changed);

	if( changed && !mLayouted ){
	mLayouted = true;

	ObjectAnimator animator;
	LayoutTransition layoutTransition = new LayoutTransition();

	animator = mAnimators.getDisappearingAnimator(getContext());
	layoutTransition.setAnimator(LayoutTransition.DISAPPEARING, animator);

	animator = mAnimators.getAppearingAnimator(getContext());
	layoutTransition.setAnimator(LayoutTransition.APPEARING, animator);

	layoutTransition.addTransitionListener(mTransitionListener);

	if( animator != null )
	layoutTransition.setDuration(animator.getDuration());

	setLayoutTransition(layoutTransition);

	if( mShowInitialAnimation )
	runInitialAnimations();

	if (mFirstVisibleCardTag != null) {
	scrollToCard(mFirstVisibleCardTag);
	mFirstVisibleCardTag = null;
	}
	}
	}

	/**
	* Check whether a user moved enough distance to start a swipe action or not.
	*
	* @param deltaX
	* @param deltaY
	* @return true if a user is swiping.
	*/
	protected boolean isSwiping(float deltaX, float deltaY) {

	if (mSwipeSlop < 0) {
	//get swipping slop from ViewConfiguration;
	mSwipeSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
	}

	boolean swipping = false;
	float absDeltaX = Math.abs(deltaX);

	if( absDeltaX > mSwipeSlop )
	return true;

	return swipping;
	}

	/**
	* Swipe a view by moving distance
	*
	* @param child a target view
	* @param deltaX x moving distance by x-axis.
	* @param deltaY y moving distance by y-axis.
	*/
	@TargetApi(Build.VERSION_CODES.HONEYCOMB)
	protected void swipeView(View child, float deltaX, float deltaY) {
	if (isFixedView(child)){
	deltaX = deltaX / 4;
	}

	float deltaXAbs = Math.abs(deltaX);
	float fractionCovered = deltaXAbs / (float) child.getWidth();

	child.setTranslationX(deltaX);
	child.setAlpha(1.f - fractionCovered);

	if (deltaX > 0)
	child.setRotationY(-15.f * fractionCovered);
	else
	child.setRotationY(15.f * fractionCovered);
	}

	protected void notifyOnDismissEvent( View child ){
	if( child == null \|\| mDismissListener == null )
	return;

	mDismissListener.onDismiss((String) child.getTag());
	}

	/**
	* get the tag of the first visible child in this layout
	*
	* @return tag of the first visible child or null
	*/
	public String getFirstVisibleCardTag() {

	final int count = getChildCount();

	if (count == 0)
	return null;

	for (int index = 0; index < count; ++index) {
	//check the position of each view.
	View child = getChildAt(index);
	if (child.getGlobalVisibleRect(mChildRect) == true)
	return (String) child.getTag();
	}

	return null;
	}

	/**
	* Set the first visible card of this linear layout.
	*
	* @param tag tag of a card which should already added to this layout.
	*/
	public void setFirstVisibleCard(String tag) {
	if (tag == null)
	return; //do nothing.

	if (mLayouted) {
	scrollToCard(tag);
	} else {
	//keep the tag for next use.
	mFirstVisibleCardTag = tag;
	}
	}

	/**
	* If this flag is set,
	* after finishing initial onLayout event, an initial animation which is defined in DefaultCardStreamAnimator is launched.
	*/
	public void triggerShowInitialAnimation(){
	mShowInitialAnimation = true;
	}

	@TargetApi(Build.VERSION_CODES.HONEYCOMB)
	public void setCardStreamAnimator( CardStreamAnimator animators ){

	if( animators == null )
	mAnimators = new CardStreamAnimator.EmptyAnimator();
	else
	mAnimators = animators;

	LayoutTransition layoutTransition = getLayoutTransition();

	if( layoutTransition != null ){
	layoutTransition.setAnimator( LayoutTransition.APPEARING,
	mAnimators.getAppearingAnimator(getContext()) );
	layoutTransition.setAnimator( LayoutTransition.DISAPPEARING,
	mAnimators.getDisappearingAnimator(getContext()) );
	}
	}

	/**
	* set a OnDismissListener which called when user dismiss a card.
	*
	* @param listener
	*/
	public void setOnDismissListener(OnDissmissListener listener) {
	mDismissListener = listener;
	}

	@TargetApi(Build.VERSION_CODES.HONEYCOMB)
	private void initialize(AttributeSet attrs, int defStyle) {

	float speedFactor = 1.f;

	if (attrs != null) {
	TypedArray a = getContext().obtainStyledAttributes(attrs,
	R.styleable.CardStream, defStyle, 0);

	if( a != null ){
	int speedType = a.getInt(R.styleable.CardStream_animationDuration, 1001);
	switch (speedType){
	case ANIMATION_SPEED_FAST:
	speedFactor = 0.5f;
	break;
	case ANIMATION_SPEED_NORMAL:
	speedFactor = 1.f;
	break;
	case ANIMATION_SPEED_SLOW:
	speedFactor = 2.f;
	break;
	}

	String animatorName = a.getString(R.styleable.CardStream_animators);

	try {
	if( animatorName != null )
	mAnimators = (CardStreamAnimator) getClass().getClassLoader()
	.loadClass(animatorName).newInstance();
	} catch (Exception e) {
	Log.e(TAG, "Fail to load animator:" + animatorName, e);
	} finally {
	if(mAnimators == null)
	mAnimators = new DefaultCardStreamAnimator();
	}
	a.recycle();
	}
	}

	mAnimators.setSpeedFactor(speedFactor);
	mSwipeSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
	setOnHierarchyChangeListener(mOnHierarchyChangeListener);
	}

	private void initCard(View cardView, boolean canDismiss) {
	resetAnimatedView(cardView);
	cardView.setOnTouchListener(mTouchListener);
	if (!canDismiss)
	mFixedViewList.add(cardView);
	}

	private boolean isFixedView(View v) {
	return mFixedViewList.contains(v);
	}

	private void resetAnimatedView(View child) {
	child.setAlpha(1.f);
	child.setTranslationX(0.f);
	child.setTranslationY(0.f);
	child.setRotation(0.f);
	child.setRotationY(0.f);
	child.setRotationX(0.f);
	child.setScaleX(1.f);
	child.setScaleY(1.f);
	}

	@TargetApi(Build.VERSION_CODES.HONEYCOMB)
	private void runInitialAnimations() {
	if( mAnimators == null )
	return;

	final int count = getChildCount();

	for (int index = 0; index < count; ++index) {
	final View child = getChildAt(index);
	ObjectAnimator animator = mAnimators.getInitalAnimator(getContext());
	if( animator != null ){
	animator.setTarget(child);
	animator.start();
	}
	}
	}

	private void runShowActionAreaAnimation(View parent, View area) {
	area.setPivotY(0.f);
	area.setPivotX(parent.getWidth() / 2.f);

	area.setAlpha(0.5f);
	area.setRotationX(-90.f);
	area.animate().rotationX(0.f).alpha(1.f).setDuration(400);
	}

	private void handleViewSwipingOut(final View child, float deltaX, float deltaY) {
	ObjectAnimator animator = mAnimators.getSwipeOutAnimator(child, deltaX, deltaY);
	if( animator != null ){
	animator.addListener(new EndAnimationWrapper() {
	@Override
	public void onAnimationEnd(Animator animation) {
	removeView(child);
	notifyOnDismissEvent(child);
	}
	});
	} else {
	removeView(child);
	notifyOnDismissEvent(child);
	}

	if( animator != null ){
	animator.setTarget(child);
	animator.start();
	}
	}

	private void handleViewSwipingIn(final View child, float deltaX, float deltaY) {
	ObjectAnimator animator = mAnimators.getSwipeInAnimator(child, deltaX, deltaY);
	if( animator != null ){
	animator.addListener(new EndAnimationWrapper() {
	@Override
	public void onAnimationEnd(Animator animation) {
	child.setTranslationY(0.f);
	child.setTranslationX(0.f);
	}
	});
	} else {
	child.setTranslationY(0.f);
	child.setTranslationX(0.f);
	}

	if( animator != null ){
	animator.setTarget(child);
	animator.start();
	}
	}

	private void scrollToCard(String tag) {


	final int count = getChildCount();
	for (int index = 0; index < count; ++index) {
	View child = getChildAt(index);

	if (tag.equals(child.getTag())) {

	ViewParent parent = getParent();
	if( parent != null && parent instanceof ScrollView ){
	((ScrollView)parent).smoothScrollTo(
	0, child.getTop() - getPaddingTop() - child.getPaddingTop());
	}
	return;
	}
	}
	}

	public interface OnDissmissListener {
	public void onDismiss(String tag);
	}

	/**
	* Empty default AnimationListener
	*/
	private abstract class EndAnimationWrapper implements Animator.AnimatorListener {

	@Override
	public void onAnimationStart(Animator animation) {
	}

	@Override
	public void onAnimationCancel(Animator animation) {
	}

	@Override
	public void onAnimationRepeat(Animator animation) {
	}
	}//end of inner class
	}