IAPDemo/Libraries/cocos2d/cocos/ui/UIListView.cpp

/****************************************************************************
Copyright (c) 2013-2017 Chukong Technologies Inc.

http://www.cocos2d-x.org

Permission is hereby granted, free of charge, to any person obtaining a copy
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all copies or substantial portions of the Software.

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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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****************************************************************************/

#include "ui/UIListView.h"
#include "ui/UIHelper.h"

NS_CC_BEGIN

static const float DEFAULT_TIME_IN_SEC_FOR_SCROLL_TO_ITEM = 1.0f;

namespace ui {
    
IMPLEMENT_CLASS_GUI_INFO(ListView)

ListView::ListView():
_model(nullptr),
_gravity(Gravity::CENTER_VERTICAL),
_magneticType(MagneticType::NONE),
_magneticAllowedOutOfBoundary(true),
_itemsMargin(0.0f),
_leftPadding(0.0f),
_topPadding(0.0f),
_rightPadding(0.0f),
_bottomPadding(0.0f),
_scrollTime(DEFAULT_TIME_IN_SEC_FOR_SCROLL_TO_ITEM),
_curSelectedIndex(-1),
_innerContainerDoLayoutDirty(true),
_listViewEventListener(nullptr),
_listViewEventSelector(nullptr),
_eventCallback(nullptr)
{
    this->setTouchEnabled(true);
}

ListView::~ListView()
{
    _listViewEventListener = nullptr;
    _listViewEventSelector = nullptr;
    _items.clear();
    CC_SAFE_RELEASE(_model);
}

ListView* ListView::create()
{
    ListView* widget = new (std::nothrow) ListView();
    if (widget && widget->init())
    {
        widget->autorelease();
        return widget;
    }
    CC_SAFE_DELETE(widget);
    return nullptr;
}

bool ListView::init()
{
    if (ScrollView::init())
    {
        setDirection(Direction::VERTICAL);
        return true;
    }
    return false;
}

void ListView::setItemModel(Widget *model)
{
    if (nullptr == model)
    {
        CCLOG("Can't set a nullptr to item model!");
        return;
    }
    CC_SAFE_RELEASE_NULL(_model);
    _model = model;
    CC_SAFE_RETAIN(_model);
}

void ListView::handleReleaseLogic(Touch *touch)
{
    ScrollView::handleReleaseLogic(touch);
    
    if(!_autoScrolling)
    {
        startMagneticScroll();
    }
}

void ListView::onItemListChanged()
{
    _outOfBoundaryAmountDirty = true;
}

void ListView::updateInnerContainerSize()
{
    switch (_direction)
    {
        case Direction::VERTICAL:
        {
            size_t length = _items.size();
            float totalHeight = (length - 1) * _itemsMargin + (_topPadding + _bottomPadding);
            for (auto& item : _items)
            {
                totalHeight += item->getContentSize().height;
            }
            float finalWidth = _contentSize.width;
            float finalHeight = totalHeight;
            setInnerContainerSize(Size(finalWidth, finalHeight));
            break;
        }
        case Direction::HORIZONTAL:
        {
            size_t length = _items.size();
            float totalWidth = (length - 1) * _itemsMargin + (_leftPadding + _rightPadding);
            for (auto& item : _items)
            {
                totalWidth += item->getContentSize().width;
            }
            float finalWidth = totalWidth;
            float finalHeight = _contentSize.height;
            setInnerContainerSize(Size(finalWidth, finalHeight));
            break;
        }
        default:
            break;
    }
}
    
void ListView::remedyVerticalLayoutParameter(LinearLayoutParameter* layoutParameter, ssize_t itemIndex)
{
    CCASSERT(nullptr != layoutParameter, "Layout parameter can't be nullptr!");
    
    switch (_gravity)
    {
        case Gravity::LEFT:
            layoutParameter->setGravity(LinearLayoutParameter::LinearGravity::LEFT);
            break;
        case Gravity::RIGHT:
            layoutParameter->setGravity(LinearLayoutParameter::LinearGravity::RIGHT);
            break;
        case Gravity::CENTER_HORIZONTAL:
            layoutParameter->setGravity(LinearLayoutParameter::LinearGravity::CENTER_HORIZONTAL);
            break;
        default:
            break;
    }
    
    if (0 == itemIndex)
    {
        layoutParameter->setMargin(Margin(_leftPadding, _topPadding, _rightPadding, 0.f));
    }
    else if (_items.size() - 1 == itemIndex)
    {
        layoutParameter->setMargin(Margin(_leftPadding, _itemsMargin, _rightPadding, _bottomPadding));
    }
    else
    {
        layoutParameter->setMargin(Margin(_leftPadding, _itemsMargin, _rightPadding, 0.0f));
    }
}
    
void ListView::remedyHorizontalLayoutParameter(LinearLayoutParameter* layoutParameter, ssize_t itemIndex)
{
    CCASSERT(nullptr != layoutParameter, "Layout parameter can't be nullptr!");
    
    switch (_gravity)
    {
        case Gravity::TOP:
            layoutParameter->setGravity(LinearLayoutParameter::LinearGravity::TOP);
            break;
        case Gravity::BOTTOM:
            layoutParameter->setGravity(LinearLayoutParameter::LinearGravity::BOTTOM);
            break;
        case Gravity::CENTER_VERTICAL:
            layoutParameter->setGravity(LinearLayoutParameter::LinearGravity::CENTER_VERTICAL);
            break;
        default:
            break;
    }
    if (0 == itemIndex)
    {
        layoutParameter->setMargin(Margin(_leftPadding, _topPadding, 0.f, _bottomPadding));
    }
    else if (_items.size() == itemIndex)
    {
        layoutParameter->setMargin(Margin(_itemsMargin, _topPadding, _rightPadding, _bottomPadding));
    }
    else
    {
        layoutParameter->setMargin(Margin(_itemsMargin, _topPadding, 0.f, _bottomPadding));
    }
}

void ListView::remedyLayoutParameter(Widget *item)
{
    CCASSERT(nullptr != item, "ListView Item can't be nullptr!");
    
    LinearLayoutParameter* linearLayoutParameter = (LinearLayoutParameter*)(item->getLayoutParameter());
    bool isLayoutParameterExists = true;
    if (!linearLayoutParameter)
    {
        linearLayoutParameter = LinearLayoutParameter::create();
        isLayoutParameterExists = false;
    }
    ssize_t itemIndex = getIndex(item);
    
    switch (_direction)
    {
        case Direction::VERTICAL:
        {
            this->remedyVerticalLayoutParameter(linearLayoutParameter, itemIndex);
            break;
        }
        case Direction::HORIZONTAL:
        {
            this->remedyHorizontalLayoutParameter(linearLayoutParameter, itemIndex);
            break;
        }
        default:
            break;
    }
    if (!isLayoutParameterExists)
    {
        item->setLayoutParameter(linearLayoutParameter);
    }
}

void ListView::pushBackDefaultItem()
{
    if (nullptr == _model)
    {
        return;
    }
    Widget* newItem = _model->clone();
    remedyLayoutParameter(newItem);
    addChild(newItem);
    requestDoLayout();
}

void ListView::insertDefaultItem(ssize_t index)
{
    if (nullptr == _model)
    {
        return;
    }
    insertCustomItem(_model->clone(), index);
}


void ListView::pushBackCustomItem(Widget* item)
{
    remedyLayoutParameter(item);
    addChild(item);
    requestDoLayout();
}
    
void ListView::addChild(cocos2d::Node *child, int zOrder, int tag)
{
    ScrollView::addChild(child, zOrder, tag);

    Widget* widget = dynamic_cast<Widget*>(child);
    if (nullptr != widget)
    {
        _items.pushBack(widget);
        onItemListChanged();
    }
}
    
void ListView::addChild(cocos2d::Node *child)
{
    ListView::addChild(child, child->getLocalZOrder(), child->getName());
}

void ListView::addChild(cocos2d::Node *child, int zOrder)
{
    ListView::addChild(child, zOrder, child->getName());
}
 
void ListView::addChild(Node* child, int zOrder, const std::string &name)
{
    ScrollView::addChild(child, zOrder, name);
    
    Widget* widget = dynamic_cast<Widget*>(child);
    if (nullptr != widget)
    {
        _items.pushBack(widget);
        onItemListChanged();
    }
}
    
void ListView::removeChild(cocos2d::Node *child, bool cleanup)
{
    Widget* widget = dynamic_cast<Widget*>(child);
    if (nullptr != widget)
    {
        if (-1 != _curSelectedIndex)
        {
            auto removedIndex = getIndex(widget);
            if (_curSelectedIndex > removedIndex)
            {
                _curSelectedIndex -= 1;
            }
            else if (_curSelectedIndex == removedIndex)
            {
                _curSelectedIndex = -1;
            }
        }
        _items.eraseObject(widget);
        onItemListChanged();
    }
   
    ScrollView::removeChild(child, cleanup);
    requestDoLayout();
}
    
void ListView::removeAllChildren()
{
    this->removeAllChildrenWithCleanup(true);
}
    
void ListView::removeAllChildrenWithCleanup(bool cleanup)
{
    ScrollView::removeAllChildrenWithCleanup(cleanup);
    _curSelectedIndex = -1;
    _items.clear();
    onItemListChanged();
}

void ListView::insertCustomItem(Widget* item, ssize_t index)
{
    if (-1 != _curSelectedIndex)
    {
        if (_curSelectedIndex >= index)
        {
            _curSelectedIndex += 1;
        }
    }
    _items.insert(index, item);
    onItemListChanged();

    ScrollView::addChild(item);

    remedyLayoutParameter(item);
    requestDoLayout();
}

void ListView::removeItem(ssize_t index)
{
    Widget* item = getItem(index);
    if (nullptr == item)
    {
        return;
    }
    removeChild(item, true);
}

void ListView::removeLastItem()
{
    removeItem(_items.size() -1);
}
    
void ListView::removeAllItems()
{
    removeAllChildren();
}

Widget* ListView::getItem(ssize_t index) const
{
    if (index < 0 || index >= _items.size())
    {
        return nullptr;
    }
    return _items.at(index);
}

Vector<Widget*>& ListView::getItems()
{
    return _items;
}

ssize_t ListView::getIndex(Widget *item) const
{
    if (nullptr == item)
    {
        return -1;
    }
    return _items.getIndex(item);
}

void ListView::setGravity(Gravity gravity)
{
    if (_gravity == gravity)
    {
        return;
    }
    _gravity = gravity;
    requestDoLayout();
}

void ListView::setMagneticType(MagneticType magneticType)
{
    _magneticType = magneticType;
    _outOfBoundaryAmountDirty = true;
    startMagneticScroll();
}

ListView::MagneticType ListView::getMagneticType() const
{
    return _magneticType;
}

void ListView::setMagneticAllowedOutOfBoundary(bool magneticAllowedOutOfBoundary)
{
    _magneticAllowedOutOfBoundary = magneticAllowedOutOfBoundary;
}

bool ListView::getMagneticAllowedOutOfBoundary() const
{
    return _magneticAllowedOutOfBoundary;
}

void ListView::setItemsMargin(float margin)
{
    if (_itemsMargin == margin)
    {
        return;
    }
    _itemsMargin = margin;
    requestDoLayout();
}
    
float ListView::getItemsMargin()const
{
    return _itemsMargin;
}

void ListView::setPadding(float l, float t, float r, float b)
{
    if (l == _leftPadding && t == _topPadding && r == _rightPadding && b == _bottomPadding)
    {
        return;
    }
    _leftPadding = l;
    _topPadding = t;
    _rightPadding = r;
    _bottomPadding = b;
    requestDoLayout();
}

void ListView::setLeftPadding(float l)
{
    if (l == _leftPadding)
    {
        return;
    }
    _leftPadding = l;
    requestDoLayout();
}

void ListView::setTopPadding(float t)
{
    if (t == _topPadding)
    {
        return;
    }
    _topPadding = t;
    requestDoLayout();
}

void ListView::setRightPadding(float r)
{
    if (r == _rightPadding)
    {
        return;
    }
    _rightPadding = r;
    requestDoLayout();
}

void ListView::setBottomPadding(float b)
{
    if (b == _bottomPadding)
    {
        return;
    }
    _bottomPadding = b;
    requestDoLayout();
}

float ListView::getLeftPadding() const
{
    return _leftPadding;
}

float ListView::getTopPadding() const
{
    return _topPadding;
}

float ListView::getRightPadding() const
{
    return _rightPadding;
}

float ListView::getBottomPadding() const
{
    return _bottomPadding;
}

void ListView::setScrollDuration(float time)
{
    if (time >= 0)
        _scrollTime = time;
}

float ListView::getScrollDuration() const 
{
    return _scrollTime;
}

void ListView::setDirection(Direction dir)
{
    switch (dir)
    {
        case Direction::NONE:
        case Direction::BOTH:
            break;
        case Direction::VERTICAL:
            setLayoutType(Type::VERTICAL);
            break;
        case Direction::HORIZONTAL:
            setLayoutType(Type::HORIZONTAL);
            break;
        default:
            return;
            break;
    }
    ScrollView::setDirection(dir);
}
    
void ListView::refreshView()
{
    forceDoLayout();
}

void ListView::requestDoLayout()
{
    _innerContainerDoLayoutDirty = true;
}

void ListView::doLayout()
{
    if(!_innerContainerDoLayoutDirty)
    {
        return;
    }

    ssize_t length = _items.size();
    for (int i = 0; i < length; ++i)
    {
        Widget* item = _items.at(i);
        item->setLocalZOrder(i);
        remedyLayoutParameter(item);
    }
    updateInnerContainerSize();
    _innerContainer->forceDoLayout();
    _innerContainerDoLayoutDirty = false;
}
    
void ListView::addEventListenerListView(Ref *target, SEL_ListViewEvent selector)
{
    _listViewEventListener = target;
    _listViewEventSelector = selector;
}

    
void ListView::addEventListener(const ccListViewCallback& callback)
{
    _eventCallback = callback;
}
    
void ListView::selectedItemEvent(TouchEventType event)
{
    this->retain();
    switch (event)
    {
        case TouchEventType::BEGAN:
        {
            if (_listViewEventListener && _listViewEventSelector)
            {
                (_listViewEventListener->*_listViewEventSelector)(this, LISTVIEW_ONSELECTEDITEM_START);
            }
            if (_eventCallback) {
                _eventCallback(this,EventType::ON_SELECTED_ITEM_START);
            }
            if (_ccEventCallback)
            {
                _ccEventCallback(this, static_cast<int>(EventType::ON_SELECTED_ITEM_START));
            }
        }
        break;
        default:
        {
            if (_listViewEventListener && _listViewEventSelector)
            {
                (_listViewEventListener->*_listViewEventSelector)(this, LISTVIEW_ONSELECTEDITEM_END);
            }
            if (_eventCallback) {
                _eventCallback(this, EventType::ON_SELECTED_ITEM_END);
            }
            if (_ccEventCallback)
            {
                _ccEventCallback(this, static_cast<int>(EventType::ON_SELECTED_ITEM_END));
            }
        }
        break;
    }
    this->release();
}
    
void ListView::interceptTouchEvent(TouchEventType event, Widget *sender, Touch* touch)
{
    ScrollView::interceptTouchEvent(event, sender, touch);
    if (!_touchEnabled)
    {
        return;
    }
    if (event != TouchEventType::MOVED)
    {
        Widget* parent = sender;
        while (parent)
        {
            if (parent && (parent->getParent() == _innerContainer))
            {
                _curSelectedIndex = getIndex(parent);
                break;
            }
            parent = dynamic_cast<Widget*>(parent->getParent());
        }
        if (sender->isHighlighted()) {
            selectedItemEvent(event);
        }
    }
}
    
static Vec2 calculateItemPositionWithAnchor(Widget* item, const Vec2& itemAnchorPoint)
{
    Vec2 origin(item->getLeftBoundary(), item->getBottomBoundary());
    Size size = item->getContentSize();
    return origin + Vec2(size.width * itemAnchorPoint.x, size.height * itemAnchorPoint.y);
}
    
static Widget* findClosestItem(const Vec2& targetPosition, const Vector<Widget*>& items, const Vec2& itemAnchorPoint, ssize_t firstIndex, float distanceFromFirst, ssize_t lastIndex, float distanceFromLast)
{
    CCASSERT(firstIndex >= 0 && lastIndex < items.size() && firstIndex <= lastIndex, "");
    if (firstIndex == lastIndex)
    {
        return items.at(firstIndex);
    }
    if (lastIndex - firstIndex == 1)
    {
        if (distanceFromFirst <= distanceFromLast)
        {
            return items.at(firstIndex);
        }
        else
        {
            return items.at(lastIndex);
        }
    }
    
    // Binary search
    ssize_t midIndex = (firstIndex + lastIndex) / 2;
    Vec2 itemPosition = calculateItemPositionWithAnchor(items.at(midIndex), itemAnchorPoint);
    float distanceFromMid = (targetPosition - itemPosition).length();
    if (distanceFromFirst <= distanceFromLast)
    {
        // Left half
        return findClosestItem(targetPosition, items, itemAnchorPoint, firstIndex, distanceFromFirst, midIndex, distanceFromMid);
    }
    else
    {
        // Right half
        return findClosestItem(targetPosition, items, itemAnchorPoint, midIndex, distanceFromMid, lastIndex, distanceFromLast);
    }
}

Widget* ListView::getClosestItemToPosition(const Vec2& targetPosition, const Vec2& itemAnchorPoint) const
{
    if (_items.empty())
    {
        return nullptr;
    }
    
    // Find the closest item through binary search
    ssize_t firstIndex = 0;
    Vec2 firstPosition = calculateItemPositionWithAnchor(_items.at(firstIndex), itemAnchorPoint);
    float distanceFromFirst = (targetPosition - firstPosition).length();
    
    ssize_t lastIndex = _items.size() - 1;
    Vec2 lastPosition = calculateItemPositionWithAnchor(_items.at(lastIndex), itemAnchorPoint);
    float distanceFromLast = (targetPosition - lastPosition).length();
    
    return findClosestItem(targetPosition, _items, itemAnchorPoint, firstIndex, distanceFromFirst, lastIndex, distanceFromLast);
}

Widget* ListView::getClosestItemToPositionInCurrentView(const Vec2& positionRatioInView, const Vec2& itemAnchorPoint) const
{
    // Calculate the target position
    Size contentSize = getContentSize();
    Vec2 targetPosition = -_innerContainer->getPosition();
    targetPosition.x += contentSize.width * positionRatioInView.x;
    targetPosition.y += contentSize.height * positionRatioInView.y;
    return getClosestItemToPosition(targetPosition, itemAnchorPoint);
}

Widget* ListView::getCenterItemInCurrentView() const
{
    return getClosestItemToPositionInCurrentView(Vec2::ANCHOR_MIDDLE, Vec2::ANCHOR_MIDDLE);
}

Widget* ListView::getLeftmostItemInCurrentView() const
{
    if (_direction == Direction::HORIZONTAL)
    {
        return getClosestItemToPositionInCurrentView(Vec2::ANCHOR_MIDDLE_LEFT, Vec2::ANCHOR_MIDDLE);
    }
    return nullptr;
}

Widget* ListView::getRightmostItemInCurrentView() const
{
    if (_direction == Direction::HORIZONTAL)
    {
        return getClosestItemToPositionInCurrentView(Vec2::ANCHOR_MIDDLE_RIGHT, Vec2::ANCHOR_MIDDLE);
    }
    return nullptr;
}

Widget* ListView::getTopmostItemInCurrentView() const
{
    if (_direction == Direction::VERTICAL)
    {
        return getClosestItemToPositionInCurrentView(Vec2::ANCHOR_MIDDLE_TOP, Vec2::ANCHOR_MIDDLE);
    }
    return nullptr;
}

Widget* ListView::getBottommostItemInCurrentView() const
{
    if (_direction == Direction::VERTICAL)
    {
        return getClosestItemToPositionInCurrentView(Vec2::ANCHOR_MIDDLE_BOTTOM, Vec2::ANCHOR_MIDDLE);
    }
    return nullptr;
}

void ListView::jumpToBottom()
{
    doLayout();
    ScrollView::jumpToBottom();
}

void ListView::jumpToTop()
{
    doLayout();
    ScrollView::jumpToTop();
}

void ListView::jumpToLeft()
{
    doLayout();
    ScrollView::jumpToLeft();
}

void ListView::jumpToRight()
{
    doLayout();
    ScrollView::jumpToRight();
}

void ListView::jumpToTopLeft()
{
    doLayout();
    ScrollView::jumpToTopLeft();
}

void ListView::jumpToTopRight()
{
    doLayout();
    ScrollView::jumpToTopRight();
}

void ListView::jumpToBottomLeft()
{
    doLayout();
    ScrollView::jumpToBottomLeft();
}

void ListView::jumpToBottomRight()
{
    doLayout();
    ScrollView::jumpToBottomRight();
}

void ListView::jumpToPercentVertical(float percent)
{
    doLayout();
    ScrollView::jumpToPercentVertical(percent);
}

void ListView::jumpToPercentHorizontal(float percent)
{
    doLayout();
    ScrollView::jumpToPercentHorizontal(percent);
}

void ListView::jumpToPercentBothDirection(const Vec2& percent)
{
    doLayout();
    ScrollView::jumpToPercentBothDirection(percent);
}

Vec2 ListView::calculateItemDestination(const Vec2& positionRatioInView, Widget* item, const Vec2& itemAnchorPoint)
{
    const Size& contentSize = getContentSize();
    Vec2 positionInView;
    positionInView.x += contentSize.width * positionRatioInView.x;
    positionInView.y += contentSize.height * positionRatioInView.y;

    Vec2 itemPosition = calculateItemPositionWithAnchor(item, itemAnchorPoint);
    return -(itemPosition - positionInView);
}

void ListView::jumpToItem(ssize_t itemIndex, const Vec2& positionRatioInView, const Vec2& itemAnchorPoint)
{
    Widget* item = getItem(itemIndex);
    if (item == nullptr)
    {
        return;
    }
    doLayout();

    Vec2 destination = calculateItemDestination(positionRatioInView, item, itemAnchorPoint);
    if(!_bounceEnabled)
    {
        Vec2 delta = destination - getInnerContainerPosition();
        Vec2 outOfBoundary = getHowMuchOutOfBoundary(delta);
        destination += outOfBoundary;
    }
    jumpToDestination(destination);
}

void ListView::scrollToItem(ssize_t itemIndex, const Vec2& positionRatioInView, const Vec2& itemAnchorPoint)
{
    scrollToItem(itemIndex, positionRatioInView, itemAnchorPoint, _scrollTime);
}

void ListView::scrollToItem(ssize_t itemIndex, const Vec2& positionRatioInView, const Vec2& itemAnchorPoint, float timeInSec)
{
    Widget* item = getItem(itemIndex);
    if (item == nullptr)
    {
        return;
    }
    Vec2 destination = calculateItemDestination(positionRatioInView, item, itemAnchorPoint);
    startAutoScrollToDestination(destination, timeInSec, true);
}

ssize_t ListView::getCurSelectedIndex() const
{
    return _curSelectedIndex;
}

void ListView::setCurSelectedIndex(int itemIndex)
{
    Widget* item = getItem(itemIndex);
    if (item == nullptr)
    {
        return;
    }
    _curSelectedIndex = itemIndex;
    this->selectedItemEvent(cocos2d::ui::Widget::TouchEventType::ENDED);
}

void ListView::onSizeChanged()
{
    ScrollView::onSizeChanged();
    requestDoLayout();
}

std::string ListView::getDescription() const
{
    return "ListView";
}

Widget* ListView::createCloneInstance()
{
    return ListView::create();
}

void ListView::copyClonedWidgetChildren(Widget* model)
{
    auto& arrayItems = static_cast<ListView*>(model)->getItems();
    for (auto& item : arrayItems)
    {
        pushBackCustomItem(item->clone());
    }
}

void ListView::copySpecialProperties(Widget *widget)
{
    ListView* listViewEx = dynamic_cast<ListView*>(widget);
    if (listViewEx)
    {
        ScrollView::copySpecialProperties(widget);
        setItemModel(listViewEx->_model);
        setItemsMargin(listViewEx->_itemsMargin);
        setGravity(listViewEx->_gravity);
        _listViewEventListener = listViewEx->_listViewEventListener;
        _listViewEventSelector = listViewEx->_listViewEventSelector;
        _eventCallback = listViewEx->_eventCallback;
    }
}

Vec2 ListView::getHowMuchOutOfBoundary(const Vec2& addition)
{
    if(!_magneticAllowedOutOfBoundary || _items.empty())
    {
        return ScrollView::getHowMuchOutOfBoundary(addition);
    }
    else if(_magneticType == MagneticType::NONE || _magneticType == MagneticType::BOTH_END)
    {
        return ScrollView::getHowMuchOutOfBoundary(addition);
    }
    else if(addition == Vec2::ZERO && !_outOfBoundaryAmountDirty)
    {
        return _outOfBoundaryAmount;
    }
    
    // If it is allowed to be out of boundary by magnetic, adjust the boundaries according to the magnetic type.
    float leftBoundary = _leftBoundary;
    float rightBoundary = _rightBoundary;
    float topBoundary = _topBoundary;
    float bottomBoundary = _bottomBoundary;
    {
        ssize_t lastItemIndex = _items.size() - 1;
        Size contentSize = getContentSize();
        Vec2 firstItemAdjustment, lastItemAdjustment;
        if(_magneticType == MagneticType::CENTER)
        {
            firstItemAdjustment = (contentSize - _items.at(0)->getContentSize()) / 2;
            lastItemAdjustment = (contentSize - _items.at(lastItemIndex)->getContentSize()) / 2;
        }
        else if(_magneticType == MagneticType::LEFT)
        {
            lastItemAdjustment = contentSize - _items.at(lastItemIndex)->getContentSize();
        }
        else if(_magneticType == MagneticType::RIGHT)
        {
            firstItemAdjustment = contentSize - _items.at(0)->getContentSize();
        }
        else if(_magneticType == MagneticType::TOP)
        {
            lastItemAdjustment = contentSize - _items.at(lastItemIndex)->getContentSize();
        }
        else if(_magneticType == MagneticType::BOTTOM)
        {
            firstItemAdjustment = contentSize - _items.at(0)->getContentSize();
        }
        leftBoundary += firstItemAdjustment.x;
        rightBoundary -= lastItemAdjustment.x;
        topBoundary -= firstItemAdjustment.y;
        bottomBoundary += lastItemAdjustment.y;
    }
    
    // Calculate the actual amount
    Vec2 outOfBoundaryAmount;
    if(_innerContainer->getLeftBoundary() + addition.x > leftBoundary)
    {
        outOfBoundaryAmount.x = leftBoundary - (_innerContainer->getLeftBoundary() + addition.x);
    }
    else if(_innerContainer->getRightBoundary() + addition.x < rightBoundary)
    {
        outOfBoundaryAmount.x = rightBoundary - (_innerContainer->getRightBoundary() + addition.x);
    }
    
    if(_innerContainer->getTopBoundary() + addition.y < topBoundary)
    {
        outOfBoundaryAmount.y = topBoundary - (_innerContainer->getTopBoundary() + addition.y);
    }
    else if(_innerContainer->getBottomBoundary() + addition.y > bottomBoundary)
    {
        outOfBoundaryAmount.y = bottomBoundary - (_innerContainer->getBottomBoundary() + addition.y);
    }
    
    if(addition == Vec2::ZERO)
    {
        _outOfBoundaryAmount = outOfBoundaryAmount;
        _outOfBoundaryAmountDirty = false;
    }
    return outOfBoundaryAmount;
}

static Vec2 getAnchorPointByMagneticType(ListView::MagneticType magneticType)
{
    switch(magneticType)
    {
        case ListView::MagneticType::NONE: return Vec2::ZERO;
        case ListView::MagneticType::BOTH_END: return Vec2::ANCHOR_TOP_LEFT;
        case ListView::MagneticType::CENTER: return Vec2::ANCHOR_MIDDLE;
        case ListView::MagneticType::LEFT: return Vec2::ANCHOR_MIDDLE_LEFT;
        case ListView::MagneticType::RIGHT: return Vec2::ANCHOR_MIDDLE_RIGHT;
        case ListView::MagneticType::TOP: return Vec2::ANCHOR_MIDDLE_TOP;
        case ListView::MagneticType::BOTTOM: return Vec2::ANCHOR_MIDDLE_BOTTOM;
    }
    return Vec2::ZERO;
}

void ListView::startAttenuatingAutoScroll(const Vec2& deltaMove, const Vec2& initialVelocity)
{
    Vec2 adjustedDeltaMove = deltaMove;
    
    if(!_items.empty() && _magneticType != MagneticType::NONE)
    {
        adjustedDeltaMove = flattenVectorByDirection(adjustedDeltaMove);

        // If the destination is out of boundary, do nothing here. Because it will be handled by bouncing back.
        if(getHowMuchOutOfBoundary(adjustedDeltaMove) == Vec2::ZERO)
        {
            MagneticType magType = _magneticType;
            if(magType == MagneticType::BOTH_END)
            {
                if(_direction == Direction::HORIZONTAL)
                {
                    magType = (adjustedDeltaMove.x > 0 ? MagneticType::LEFT : MagneticType::RIGHT);
                }
                else if(_direction == Direction::VERTICAL)
                {
                    magType = (adjustedDeltaMove.y > 0 ? MagneticType::BOTTOM : MagneticType::TOP);
                }
            }
            
            // Adjust the delta move amount according to the magnetic type
            Vec2 magneticAnchorPoint = getAnchorPointByMagneticType(magType);
            Vec2 magneticPosition = -_innerContainer->getPosition();
            magneticPosition.x += getContentSize().width * magneticAnchorPoint.x;
            magneticPosition.y += getContentSize().height * magneticAnchorPoint.y;
            
            Widget* pTargetItem = getClosestItemToPosition(magneticPosition - adjustedDeltaMove, magneticAnchorPoint);
            Vec2 itemPosition = calculateItemPositionWithAnchor(pTargetItem, magneticAnchorPoint);
            adjustedDeltaMove = magneticPosition - itemPosition;
        }
    }
    ScrollView::startAttenuatingAutoScroll(adjustedDeltaMove, initialVelocity);
}

void ListView::startMagneticScroll()
{
    if(_items.empty() || _magneticType == MagneticType::NONE)
    {
        return;
    }
    
    // Find the closest item
    Vec2 magneticAnchorPoint = getAnchorPointByMagneticType(_magneticType);
    Vec2 magneticPosition = -_innerContainer->getPosition();
    magneticPosition.x += getContentSize().width * magneticAnchorPoint.x;
    magneticPosition.y += getContentSize().height * magneticAnchorPoint.y;
    
    Widget* pTargetItem = getClosestItemToPosition(magneticPosition, magneticAnchorPoint);
    scrollToItem(getIndex(pTargetItem), magneticAnchorPoint, magneticAnchorPoint);
}

}
NS_CC_END