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** This file is part of the QtDeclarative module of the Qt Toolkit.
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****************************************************************************/

#include "qquicklistview_p.h"
#include "qquickitemview_p_p.h"
#include "qquickvisualitemmodel_p.h"

#include <QtDeclarative/qdeclarativeexpression.h>
#include <QtDeclarative/qdeclarativeengine.h>
#include <QtDeclarative/qdeclarativeinfo.h>
#include <QtGui/qevent.h>
#include <QtCore/qmath.h>
#include <QtCore/qcoreapplication.h>

#include <private/qdeclarativesmoothedanimation_p_p.h>
#include <private/qlistmodelinterface_p.h>
#include "qplatformdefs.h"

QT_BEGIN_NAMESPACE

#ifndef QML_FLICK_SNAPONETHRESHOLD
#define QML_FLICK_SNAPONETHRESHOLD 30
#endif

//#define DEBUG_DELEGATE_LIFECYCLE

class FxListItemSG;

class QQuickListViewPrivate : public QQuickItemViewPrivate
{
    Q_DECLARE_PUBLIC(QQuickListView)
public:
    static QQuickListViewPrivate* get(QQuickListView *item) { return item->d_func(); }

    virtual Qt::Orientation layoutOrientation() const;
    virtual bool isContentFlowReversed() const;
    bool isRightToLeft() const;

    virtual qreal positionAt(int index) const;
    virtual qreal endPositionAt(int index) const;
    virtual qreal originPosition() const;
    virtual qreal lastPosition() const;

    FxViewItem *itemBefore(int modelIndex) const;
    QString sectionAt(int modelIndex);
    qreal snapPosAt(qreal pos);
    FxViewItem *snapItemAt(qreal pos);

    virtual void init();
    virtual void clear();

    virtual bool addVisibleItems(qreal fillFrom, qreal fillTo, bool doBuffer);
    virtual bool removeNonVisibleItems(qreal bufferFrom, qreal bufferTo);
    virtual void visibleItemsChanged();

    virtual FxViewItem *newViewItem(int index, QQuickItem *item);
    virtual void initializeViewItem(FxViewItem *item);
    virtual void releaseItem(FxViewItem *item);
    virtual void repositionPackageItemAt(QQuickItem *item, int index);
    virtual void resetFirstItemPosition(qreal pos = 0.0);
    virtual void adjustFirstItem(qreal forwards, qreal backwards, int);

    virtual void createHighlight();
    virtual void updateHighlight();
    virtual void resetHighlightPosition();

    virtual void setPosition(qreal pos);
    virtual void layoutVisibleItems(int fromModelIndex = 0);
    virtual bool applyInsertionChange(const QDeclarativeChangeSet::Insert &insert, ChangeResult *changeResult, QList<FxViewItem *> *addedItems);

    virtual void updateSections();
    QQuickItem *getSectionItem(const QString &section);
    void releaseSectionItem(QQuickItem *item);
    void updateInlineSection(FxListItemSG *);
    void updateCurrentSection();
    void updateStickySections();

    virtual qreal headerSize() const;
    virtual qreal footerSize() const;
    virtual bool showHeaderForIndex(int index) const;
    virtual bool showFooterForIndex(int index) const;
    virtual void updateHeader();
    virtual void updateFooter();

    virtual void changedVisibleIndex(int newIndex);
    virtual void initializeCurrentItem();

    void updateAverage();

    void itemGeometryChanged(QQuickItem *item, const QRectF &newGeometry, const QRectF &oldGeometry);
    virtual void fixupPosition();
    virtual void fixup(AxisData &data, qreal minExtent, qreal maxExtent);
    virtual void flick(QQuickItemViewPrivate::AxisData &data, qreal minExtent, qreal maxExtent, qreal vSize,
                        QDeclarativeTimeLineCallback::Callback fixupCallback, qreal velocity);

    QQuickListView::Orientation orient;
    qreal visiblePos;
    qreal averageSize;
    qreal spacing;
    QQuickListView::SnapMode snapMode;

    QSmoothedAnimation *highlightPosAnimator;
    QSmoothedAnimation *highlightSizeAnimator;
    qreal highlightMoveSpeed;
    qreal highlightResizeSpeed;
    int highlightResizeDuration;

    QQuickViewSection *sectionCriteria;
    QString currentSection;
    static const int sectionCacheSize = 5;
    QQuickItem *sectionCache[sectionCacheSize];
    QQuickItem *currentSectionItem;
    QString currentStickySection;
    QQuickItem *nextSectionItem;
    QString nextStickySection;
    QString lastVisibleSection;
    QString nextSection;

    qreal overshootDist;
    bool correctFlick : 1;
    bool inFlickCorrection : 1;

    QQuickListViewPrivate()
        : orient(QQuickListView::Vertical)
        , visiblePos(0)
        , averageSize(100.0), spacing(0.0)
        , snapMode(QQuickListView::NoSnap)
        , highlightPosAnimator(0), highlightSizeAnimator(0)
        , highlightMoveSpeed(400), highlightResizeSpeed(400), highlightResizeDuration(-1)
        , sectionCriteria(0), currentSectionItem(0), nextSectionItem(0)
        , overshootDist(0.0), correctFlick(false), inFlickCorrection(false)
    {}
    ~QQuickListViewPrivate() {
        delete highlightPosAnimator;
        delete highlightSizeAnimator;
    }

    friend class QQuickViewSection;
};

//----------------------------------------------------------------------------

QQuickViewSection::QQuickViewSection(QQuickListView *parent)
    : QObject(parent), m_criteria(FullString), m_delegate(0), m_labelPositioning(InlineLabels)
    , m_view(parent ? QQuickListViewPrivate::get(parent) : 0)
{
}

void QQuickViewSection::setProperty(const QString &property)
{
    if (property != m_property) {
        m_property = property;
        emit propertyChanged();
        m_view->updateSections();
    }
}

void QQuickViewSection::setCriteria(QQuickViewSection::SectionCriteria criteria)
{
    if (criteria != m_criteria) {
        m_criteria = criteria;
        emit criteriaChanged();
        m_view->updateSections();
    }
}

void QQuickViewSection::setDelegate(QDeclarativeComponent *delegate)
{
    if (delegate != m_delegate) {
        m_delegate = delegate;
        emit delegateChanged();
        m_view->updateSections();
    }
}

QString QQuickViewSection::sectionString(const QString &value)
{
    if (m_criteria == FirstCharacter)
        return value.isEmpty() ? QString() : value.at(0);
    else
        return value;
}

void QQuickViewSection::setLabelPositioning(int l)
{
    if (m_labelPositioning != l) {
        m_labelPositioning = l;
        emit labelPositioningChanged();
        m_view->updateSections();
    }
}

//----------------------------------------------------------------------------

class FxListItemSG : public FxViewItem
{
public:
    FxListItemSG(QQuickItem *i, QQuickListView *v, bool own) : FxViewItem(i, own), section(0), view(v) {
        attached = static_cast<QQuickListViewAttached*>(qmlAttachedPropertiesObject<QQuickListView>(item));
        if (attached)
            static_cast<QQuickListViewAttached*>(attached)->setView(view);
    }

    ~FxListItemSG() {}

    qreal position() const {
        if (section) {
            if (view->orientation() == QQuickListView::Vertical)
                return section->y();
            else
                return (view->effectiveLayoutDirection() == Qt::RightToLeft ? -section->width()-section->x() : section->x());
        } else {
            return itemPosition();
        }
    }
    qreal itemPosition() const {
        if (view->orientation() == QQuickListView::Vertical)
            return item->y();
        else
            return (view->effectiveLayoutDirection() == Qt::RightToLeft ? -item->width()-item->x() : item->x());
    }
    qreal size() const {
        if (section)
            return (view->orientation() == QQuickListView::Vertical ? item->height()+section->height() : item->width()+section->width());
        else
            return (view->orientation() == QQuickListView::Vertical ? item->height() : item->width());
    }
    qreal itemSize() const {
        return (view->orientation() == QQuickListView::Vertical ? item->height() : item->width());
    }
    qreal sectionSize() const {
        if (section)
            return (view->orientation() == QQuickListView::Vertical ? section->height() : section->width());
        return 0.0;
    }
    qreal endPosition() const {
        if (view->orientation() == QQuickListView::Vertical) {
            return item->y() + item->height();
        } else {
            return (view->effectiveLayoutDirection() == Qt::RightToLeft
                    ? -item->x()
                    : item->x() + item->width());
        }
    }
    void setPosition(qreal pos) {
        if (view->orientation() == QQuickListView::Vertical) {
            if (section) {
                section->setY(pos);
                pos += section->height();
            }
            item->setY(pos);
        } else {
            if (view->effectiveLayoutDirection() == Qt::RightToLeft) {
                if (section) {
                    section->setX(-section->width()-pos);
                    pos += section->width();
                }
                item->setX(-item->width()-pos);
            } else {
                if (section) {
                    section->setX(pos);
                    pos += section->width();
                }
                item->setX(pos);
            }
        }
    }
    void setSize(qreal size) {
        if (view->orientation() == QQuickListView::Vertical)
            item->setHeight(size);
        else
            item->setWidth(size);
    }
    bool contains(qreal x, qreal y) const {
        return (x >= item->x() && x < item->x() + item->width() &&
                y >= item->y() && y < item->y() + item->height());
    }

    QQuickItem *section;
    QQuickListView *view;
};

//----------------------------------------------------------------------------

bool QQuickListViewPrivate::isContentFlowReversed() const
{
    return isRightToLeft();
}

Qt::Orientation QQuickListViewPrivate::layoutOrientation() const
{
    return static_cast<Qt::Orientation>(orient);
}

bool QQuickListViewPrivate::isRightToLeft() const
{
    Q_Q(const QQuickListView);
    return orient == QQuickListView::Horizontal && q->effectiveLayoutDirection() == Qt::RightToLeft;
}

// Returns the item before modelIndex, if created.
// May return an item marked for removal.
FxViewItem *QQuickListViewPrivate::itemBefore(int modelIndex) const
{
    if (modelIndex < visibleIndex)
        return 0;
    int idx = 1;
    int lastIndex = -1;
    while (idx < visibleItems.count()) {
        FxViewItem *item = visibleItems.at(idx);
        if (item->index != -1)
            lastIndex = item->index;
        if (item->index == modelIndex)
            return visibleItems.at(idx-1);
        ++idx;
    }
    if (lastIndex == modelIndex-1)
        return visibleItems.last();
    return 0;
}

void QQuickListViewPrivate::setPosition(qreal pos)
{
    Q_Q(QQuickListView);
    if (orient == QQuickListView::Vertical) {
        q->QQuickFlickable::setContentY(pos);
    } else {
        if (isRightToLeft())
            q->QQuickFlickable::setContentX(-pos-size());
        else
            q->QQuickFlickable::setContentX(pos);
    }
}

qreal QQuickListViewPrivate::originPosition() const
{
    qreal pos = 0;
    if (!visibleItems.isEmpty()) {
        pos = (*visibleItems.constBegin())->position();
        if (visibleIndex > 0)
            pos -= visibleIndex * (averageSize + spacing);
    }
    return pos;
}

qreal QQuickListViewPrivate::lastPosition() const
{
    qreal pos = 0;
    if (!visibleItems.isEmpty()) {
        int invisibleCount = visibleItems.count() - visibleIndex;
        for (int i = visibleItems.count()-1; i >= 0; --i) {
            if (visibleItems.at(i)->index != -1) {
                invisibleCount = model->count() - visibleItems.at(i)->index - 1;
                break;
            }
        }
        pos = (*(--visibleItems.constEnd()))->endPosition() + invisibleCount * (averageSize + spacing);
    } else if (model && model->count()) {
        pos = (model->count() * averageSize + (model->count()-1) * spacing);
    }
    return pos;
}

qreal QQuickListViewPrivate::positionAt(int modelIndex) const
{
    if (FxViewItem *item = visibleItem(modelIndex))
        return item->position();
    if (!visibleItems.isEmpty()) {
        if (modelIndex < visibleIndex) {
            int count = visibleIndex - modelIndex;
            qreal cs = 0;
            if (modelIndex == currentIndex && currentItem) {
                cs = currentItem->size() + spacing;
                --count;
            }
            return (*visibleItems.constBegin())->position() - count * (averageSize + spacing) - cs;
        } else {
            int count = modelIndex - findLastVisibleIndex(visibleIndex) - 1;
            return (*(--visibleItems.constEnd()))->endPosition() + spacing + count * (averageSize + spacing);
        }
    }
    return 0;
}

qreal QQuickListViewPrivate::endPositionAt(int modelIndex) const
{
    if (FxViewItem *item = visibleItem(modelIndex))
        return item->endPosition();
    if (!visibleItems.isEmpty()) {
        if (modelIndex < visibleIndex) {
            int count = visibleIndex - modelIndex;
            return (*visibleItems.constBegin())->position() - (count - 1) * (averageSize + spacing) - spacing;
        } else {
            int count = modelIndex - findLastVisibleIndex(visibleIndex) - 1;
            return (*(--visibleItems.constEnd()))->endPosition() + count * (averageSize + spacing);
        }
    }
    return 0;
}

QString QQuickListViewPrivate::sectionAt(int modelIndex)
{
    if (FxViewItem *item = visibleItem(modelIndex))
        return item->attached->section();

    QString section;
    if (sectionCriteria) {
        QString propValue = model->stringValue(modelIndex, sectionCriteria->property());
        section = sectionCriteria->sectionString(propValue);
    }

    return section;
}

qreal QQuickListViewPrivate::snapPosAt(qreal pos)
{
    if (FxViewItem *snapItem = snapItemAt(pos))
        return snapItem->position();
    if (visibleItems.count()) {
        qreal firstPos = (*visibleItems.constBegin())->position();
        qreal endPos = (*(--visibleItems.constEnd()))->position();
        if (pos < firstPos) {
            return firstPos - qRound((firstPos - pos) / averageSize) * averageSize;
        } else if (pos > endPos)
            return endPos + qRound((pos - endPos) / averageSize) * averageSize;
    }
    return qRound((pos - originPosition()) / averageSize) * averageSize + originPosition();
}

FxViewItem *QQuickListViewPrivate::snapItemAt(qreal pos)
{
    FxViewItem *snapItem = 0;
    qreal prevItemSize = 0;
    for (int i = 0; i < visibleItems.count(); ++i) {
        FxViewItem *item = visibleItems.at(i);
        if (item->index == -1)
            continue;
        qreal itemTop = item->position();
        if (highlight && itemTop >= pos && item->endPosition() <= pos + highlight->size())
            return item;
        if (itemTop+item->size()/2 >= pos && itemTop-prevItemSize/2 < pos)
            snapItem = item;
        prevItemSize = item->size();
    }
    return snapItem;
}

void QQuickListViewPrivate::changedVisibleIndex(int newIndex)
{
    visiblePos = positionAt(newIndex);
    visibleIndex = newIndex;
}

void QQuickListViewPrivate::init()
{
    QQuickItemViewPrivate::init();
    ::memset(sectionCache, 0, sizeof(QQuickItem*) * sectionCacheSize);
}

void QQuickListViewPrivate::clear()
{
    for (int i = 0; i < sectionCacheSize; ++i) {
        delete sectionCache[i];
        sectionCache[i] = 0;
    }
    visiblePos = 0;
    currentSectionItem = 0;
    nextSectionItem = 0;
    lastVisibleSection = QString();
    QQuickItemViewPrivate::clear();
}

FxViewItem *QQuickListViewPrivate::newViewItem(int modelIndex, QQuickItem *item)
{
    Q_Q(QQuickListView);

    FxListItemSG *listItem = new FxListItemSG(item, q, false);
    listItem->index = modelIndex;

    // initialise attached properties
    if (sectionCriteria) {
        QString propValue = model->stringValue(modelIndex, sectionCriteria->property());
        listItem->attached->m_section = sectionCriteria->sectionString(propValue);
        if (modelIndex > 0) {
            if (FxViewItem *item = itemBefore(modelIndex))
                listItem->attached->m_prevSection = item->attached->section();
            else
                listItem->attached->m_prevSection = sectionAt(modelIndex-1);
        }
        if (modelIndex < model->count()-1) {
            if (FxViewItem *item = visibleItem(modelIndex+1))
                listItem->attached->m_nextSection = static_cast<QQuickListViewAttached*>(item->attached)->section();
            else
                listItem->attached->m_nextSection = sectionAt(modelIndex+1);
        }
    }

    return listItem;
}

void QQuickListViewPrivate::initializeViewItem(FxViewItem *item)
{
    QQuickItemViewPrivate::initializeViewItem(item);

    QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(item->item);
    itemPrivate->addItemChangeListener(this, QQuickItemPrivate::Geometry);

    if (sectionCriteria && sectionCriteria->delegate()) {
        if (item->attached->m_prevSection != item->attached->m_section)
            updateInlineSection(static_cast<FxListItemSG*>(item));
    }
}

void QQuickListViewPrivate::releaseItem(FxViewItem *item)
{
    if (item) {
        FxListItemSG* listItem = static_cast<FxListItemSG*>(item);
        if (listItem->section) {
            int i = 0;
            do {
                if (!sectionCache[i]) {
                    sectionCache[i] = listItem->section;
                    sectionCache[i]->setVisible(false);
                    listItem->section = 0;
                    break;
                }
                ++i;
            } while (i < sectionCacheSize);
            delete listItem->section;
        }
    }
    QQuickItemViewPrivate::releaseItem(item);
}

bool QQuickListViewPrivate::addVisibleItems(qreal fillFrom, qreal fillTo, bool doBuffer)
{
    qreal itemEnd = visiblePos;
    if (visibleItems.count()) {
        visiblePos = (*visibleItems.constBegin())->position();
        itemEnd = (*(--visibleItems.constEnd()))->endPosition() + spacing;
    }

    int modelIndex = findLastVisibleIndex();
    bool haveValidItems = modelIndex >= 0;
    modelIndex = modelIndex < 0 ? visibleIndex : modelIndex + 1;

    if (haveValidItems && (fillFrom > itemEnd+averageSize+spacing
        || fillTo < visiblePos - averageSize - spacing)) {
        // We've jumped more than a page.  Estimate which items are now
        // visible and fill from there.
        int count = (fillFrom - itemEnd) / (averageSize + spacing);
        for (int i = 0; i < visibleItems.count(); ++i)
            releaseItem(visibleItems.at(i));
        visibleItems.clear();
        modelIndex += count;
        if (modelIndex >= model->count()) {
            count -= modelIndex - model->count() + 1;
            modelIndex = model->count() - 1;
        } else if (modelIndex < 0) {
            count -= modelIndex;
            modelIndex = 0;
        }
        visibleIndex = modelIndex;
        visiblePos = itemEnd + count * (averageSize + spacing);
        itemEnd = visiblePos;
    }

    bool changed = false;
    FxListItemSG *item = 0;
    qreal pos = itemEnd;
    while (modelIndex < model->count() && pos <= fillTo) {
#ifdef DEBUG_DELEGATE_LIFECYCLE
        qDebug() << "refill: append item" << modelIndex << "pos" << pos;
#endif
        if (!(item = static_cast<FxListItemSG*>(createItem(modelIndex, doBuffer))))
            break;
        item->setPosition(pos);
        item->item->setVisible(!doBuffer);
        pos += item->size() + spacing;
        visibleItems.append(item);
        ++modelIndex;
        changed = true;
    }

    if (doBuffer && requestedIndex != -1) // already waiting for an item
        return changed;

    while (visibleIndex > 0 && visibleIndex <= model->count() && visiblePos > fillFrom) {
#ifdef DEBUG_DELEGATE_LIFECYCLE
        qDebug() << "refill: prepend item" << visibleIndex-1 << "current top pos" << visiblePos;
#endif
        if (!(item = static_cast<FxListItemSG*>(createItem(visibleIndex-1, doBuffer))))
            break;
        --visibleIndex;
        visiblePos -= item->size() + spacing;
        item->setPosition(visiblePos);
        item->item->setVisible(!doBuffer);
        visibleItems.prepend(item);
        changed = true;
    }

    return changed;
}

bool QQuickListViewPrivate::removeNonVisibleItems(qreal bufferFrom, qreal bufferTo)
{
    FxViewItem *item = 0;
    bool changed = false;

    // Remove items from the start of the view.
    // Zero-sized items shouldn't be removed unless a non-zero-sized item is also being
    // removed, otherwise a zero-sized item is infinitely added and removed over and
    // over by refill().
    int index = 0;
    while (visibleItems.count() > 1 && index < visibleItems.count()
           && (item = visibleItems.at(index)) && item->endPosition() < bufferFrom) {
        if (item->attached->delayRemove())
            break;
        if (item->size() > 0) {
#ifdef DEBUG_DELEGATE_LIFECYCLE
            qDebug() << "refill: remove first" << visibleIndex << "top end pos" << item->endPosition();
#endif
            // remove this item and all zero-sized items before it
            while (item) {
                if (item->index != -1)
                    visibleIndex++;
                visibleItems.removeAt(index);
                releaseItem(item);
                if (index == 0)
                    break;
                item = visibleItems.at(--index);
            }
            changed = true;
        } else {
            index++;
        }
    }

    while (visibleItems.count() > 1 && (item = visibleItems.last()) && item->position() > bufferTo) {
        if (item->attached->delayRemove())
            break;
#ifdef DEBUG_DELEGATE_LIFECYCLE
        qDebug() << "refill: remove last" << visibleIndex+visibleItems.count()-1 << item->position();
#endif
        visibleItems.removeLast();
        releaseItem(item);
        changed = true;
    }

    return changed;
}

void QQuickListViewPrivate::visibleItemsChanged()
{
    if (visibleItems.count())
        visiblePos = (*visibleItems.constBegin())->position();
    updateAverage();
    if (currentIndex >= 0 && currentItem && !visibleItem(currentIndex)) {
        static_cast<FxListItemSG*>(currentItem)->setPosition(positionAt(currentIndex));
        updateHighlight();
    }
    if (sectionCriteria)
        updateCurrentSection();
    updateUnrequestedPositions();
}

void QQuickListViewPrivate::layoutVisibleItems(int fromModelIndex)
{
    if (!visibleItems.isEmpty()) {
        const qreal from = isContentFlowReversed() ? -position() - size() : position();
        const qreal to = isContentFlowReversed() ? -position() : position() + size();

        FxViewItem *firstItem = *visibleItems.constBegin();
        bool fixedCurrent = currentItem && firstItem->item == currentItem->item;
        qreal sum = firstItem->size();
        qreal pos = firstItem->position() + firstItem->size() + spacing;
        firstItem->item->setVisible(firstItem->endPosition() >= from && firstItem->position() <= to);
        for (int i=1; i < visibleItems.count(); ++i) {
            FxListItemSG *item = static_cast<FxListItemSG*>(visibleItems.at(i));
            if (item->index >= fromModelIndex) {
                item->setPosition(pos);
                item->item->setVisible(item->endPosition() >= from && item->position() <= to);
            }
            pos += item->size() + spacing;
            sum += item->size();
            fixedCurrent = fixedCurrent || (currentItem && item->item == currentItem->item);
        }
        averageSize = qRound(sum / visibleItems.count());

        // move current item if it is not a visible item.
        if (currentIndex >= 0 && currentItem && !fixedCurrent) {
            static_cast<FxListItemSG*>(currentItem)->setPosition(positionAt(currentIndex));
        }
    }
}

void QQuickListViewPrivate::repositionPackageItemAt(QQuickItem *item, int index)
{
    Q_Q(QQuickListView);
    qreal pos = position();
    if (orient == QQuickListView::Vertical) {
        if (item->y() + item->height() > pos && item->y() < pos + q->height())
            item->setY(positionAt(index));
    } else {
        if (item->x() + item->width() > pos && item->x() < pos + q->width()) {
            if (isRightToLeft())
                item->setX(-positionAt(index)-item->width());
            else
                item->setX(positionAt(index));
        }
    }
}

void QQuickListViewPrivate::resetFirstItemPosition(qreal pos)
{
    FxListItemSG *item = static_cast<FxListItemSG*>(visibleItems.first());
    item->setPosition(pos);
}

void QQuickListViewPrivate::adjustFirstItem(qreal forwards, qreal backwards, int)
{
    if (!visibleItems.count())
        return;
    qreal diff = forwards - backwards;
    static_cast<FxListItemSG*>(visibleItems.first())->setPosition(visibleItems.first()->position() + diff);
}

void QQuickListViewPrivate::createHighlight()
{
    Q_Q(QQuickListView);
    bool changed = false;
    if (highlight) {
        if (trackedItem == highlight)
            trackedItem = 0;
        delete highlight;
        highlight = 0;

        delete highlightPosAnimator;
        delete highlightSizeAnimator;
        highlightPosAnimator = 0;
        highlightSizeAnimator = 0;

        changed = true;
    }

    if (currentItem) {
        QQuickItem *item = createHighlightItem();
        if (item) {
            FxListItemSG *newHighlight = new FxListItemSG(item, q, true);

            if (autoHighlight) {
                newHighlight->setSize(static_cast<FxListItemSG*>(currentItem)->itemSize());
                newHighlight->setPosition(static_cast<FxListItemSG*>(currentItem)->itemPosition());
            }
            const QLatin1String posProp(orient == QQuickListView::Vertical ? "y" : "x");
            highlightPosAnimator = new QSmoothedAnimation;
            highlightPosAnimator->target = QDeclarativeProperty(item, posProp);
            highlightPosAnimator->velocity = highlightMoveSpeed;
            highlightPosAnimator->userDuration = highlightMoveDuration;

            const QLatin1String sizeProp(orient == QQuickListView::Vertical ? "height" : "width");
            highlightSizeAnimator = new QSmoothedAnimation;
            highlightSizeAnimator->velocity = highlightResizeSpeed;
            highlightSizeAnimator->userDuration = highlightResizeDuration;
            highlightSizeAnimator->target = QDeclarativeProperty(item, sizeProp);

            highlight = newHighlight;
            changed = true;
        }
    }
    if (changed)
        emit q->highlightItemChanged();
}

void QQuickListViewPrivate::updateHighlight()
{
    applyPendingChanges();

    if ((!currentItem && highlight) || (currentItem && !highlight))
        createHighlight();
    bool strictHighlight = haveHighlightRange && highlightRange == QQuickListView::StrictlyEnforceRange;
    if (currentItem && autoHighlight && highlight && (!strictHighlight || !pressed)) {
        // auto-update highlight
        FxListItemSG *listItem = static_cast<FxListItemSG*>(currentItem);
        highlightPosAnimator->to = isRightToLeft()
                ? -listItem->itemPosition()-listItem->itemSize()
                : listItem->itemPosition();
        highlightSizeAnimator->to = listItem->itemSize();
        if (orient == QQuickListView::Vertical) {
            if (highlight->item->width() == 0)
                highlight->item->setWidth(currentItem->item->width());
        } else {
            if (highlight->item->height() == 0)
                highlight->item->setHeight(currentItem->item->height());
        }

        highlightPosAnimator->restart();
        highlightSizeAnimator->restart();
    }
    updateTrackedItem();
}

void QQuickListViewPrivate::resetHighlightPosition()
{
    if (highlight && currentItem)
        static_cast<FxListItemSG*>(highlight)->setPosition(static_cast<FxListItemSG*>(currentItem)->itemPosition());
}

QQuickItem * QQuickListViewPrivate::getSectionItem(const QString &section)
{
    Q_Q(QQuickListView);
    QQuickItem *sectionItem = 0;
    int i = sectionCacheSize-1;
    while (i >= 0 && !sectionCache[i])
        --i;
    if (i >= 0) {
        sectionItem = sectionCache[i];
        sectionCache[i] = 0;
        sectionItem->setVisible(true);
        QDeclarativeContext *context = QDeclarativeEngine::contextForObject(sectionItem)->parentContext();
        context->setContextProperty(QLatin1String("section"), section);
    } else {
        QDeclarativeContext *creationContext = sectionCriteria->delegate()->creationContext();
        QDeclarativeContext *context = new QDeclarativeContext(
                creationContext ? creationContext : qmlContext(q));
        context->setContextProperty(QLatin1String("section"), section);
        QObject *nobj = sectionCriteria->delegate()->beginCreate(context);
        if (nobj) {
            QDeclarative_setParent_noEvent(context, nobj);
            sectionItem = qobject_cast<QQuickItem *>(nobj);
            if (!sectionItem) {
                delete nobj;
            } else {
                sectionItem->setZ(2);
                QDeclarative_setParent_noEvent(sectionItem, contentItem);
                sectionItem->setParentItem(contentItem);
            }
        } else {
            delete context;
        }
        sectionCriteria->delegate()->completeCreate();
    }

    return sectionItem;
}

void QQuickListViewPrivate::releaseSectionItem(QQuickItem *item)
{
    int i = 0;
    do {
        if (!sectionCache[i]) {
            sectionCache[i] = item;
            sectionCache[i]->setVisible(false);
            return;
        }
        ++i;
    } while (i < sectionCacheSize);
    delete item;
}

void QQuickListViewPrivate::updateInlineSection(FxListItemSG *listItem)
{
    if (!sectionCriteria || !sectionCriteria->delegate())
        return;
    if (listItem->attached->m_prevSection != listItem->attached->m_section
            && (sectionCriteria->labelPositioning() & QQuickViewSection::InlineLabels
                || (listItem->index == 0 && sectionCriteria->labelPositioning() & QQuickViewSection::CurrentLabelAtStart))) {
        if (!listItem->section) {
            qreal pos = listItem->position();
            listItem->section = getSectionItem(listItem->attached->m_section);
            listItem->setPosition(pos);
        } else {
            QDeclarativeContext *context = QDeclarativeEngine::contextForObject(listItem->section)->parentContext();
            context->setContextProperty(QLatin1String("section"), listItem->attached->m_section);
        }
    } else if (listItem->section) {
        qreal pos = listItem->position();
        releaseSectionItem(listItem->section);
        listItem->section = 0;
        listItem->setPosition(pos);
    }
}

void QQuickListViewPrivate::updateStickySections()
{
    if (!sectionCriteria || visibleItems.isEmpty()
            || (!sectionCriteria->labelPositioning() && !currentSectionItem && !nextSectionItem))
        return;

    bool isRtl = isRightToLeft();
    qreal viewPos = isRightToLeft() ? -position()-size() : position();
    QQuickItem *sectionItem = 0;
    QQuickItem *lastSectionItem = 0;
    int index = 0;
    while (index < visibleItems.count()) {
        if (QQuickItem *section = static_cast<FxListItemSG *>(visibleItems.at(index))->section) {
            // Find the current section header and last visible section header
            // and hide them if they will overlap a static section header.
            qreal sectionPos = orient == QQuickListView::Vertical ? section->y() : section->x();
            qreal sectionSize = orient == QQuickListView::Vertical ? section->height() : section->width();
            bool visTop = true;
            if (sectionCriteria->labelPositioning() & QQuickViewSection::CurrentLabelAtStart)
                visTop = isRtl ? -sectionPos-sectionSize >= viewPos : sectionPos >= viewPos;
            bool visBot = true;
            if (sectionCriteria->labelPositioning() & QQuickViewSection::NextLabelAtEnd)
                visBot = isRtl ? -sectionPos <= viewPos + size() : sectionPos + sectionSize < viewPos + size();
            section->setVisible(visBot && visTop);
            if (visTop && !sectionItem)
                sectionItem = section;
            if (isRtl) {
               if (-sectionPos <= viewPos + size())
                    lastSectionItem = section;
            } else {
                if (sectionPos + sectionSize < viewPos + size())
                    lastSectionItem = section;
            }
        }
        ++index;
    }

    // Current section header
    if (sectionCriteria->labelPositioning() & QQuickViewSection::CurrentLabelAtStart) {
        if (!currentSectionItem) {
            currentSectionItem = getSectionItem(currentSection);
        } else if (currentStickySection != currentSection) {
            QDeclarativeContext *context = QDeclarativeEngine::contextForObject(currentSectionItem)->parentContext();
            context->setContextProperty(QLatin1String("section"), currentSection);
        }
        currentStickySection = currentSection;
        if (!currentSectionItem)
            return;

        qreal sectionSize = orient == QQuickListView::Vertical ? currentSectionItem->height() : currentSectionItem->width();
        bool atBeginning = orient == QQuickListView::Vertical ? vData.atBeginning : (isRightToLeft() ? hData.atEnd : hData.atBeginning);
        currentSectionItem->setVisible(!atBeginning && (!header || header->endPosition() < viewPos));
        qreal pos = isRtl ? position() + size() - sectionSize : viewPos;
        if (sectionItem) {
            qreal sectionPos = orient == QQuickListView::Vertical ? sectionItem->y() : sectionItem->x();
            pos = isRtl ? qMax(pos, sectionPos + sectionSize) : qMin(pos, sectionPos - sectionSize);
        }
        if (header)
            pos = isRtl ? qMin(header->endPosition(), pos) : qMax(header->endPosition(), pos);
        if (footer)
            pos = isRtl ? qMax(-footer->position(), pos) : qMin(footer->position() - sectionSize, pos);
        if (orient == QQuickListView::Vertical)
            currentSectionItem->setY(pos);
        else
            currentSectionItem->setX(pos);
    } else if (currentSectionItem) {
        releaseSectionItem(currentSectionItem);
        currentSectionItem = 0;
    }

    // Next section footer
    if (sectionCriteria->labelPositioning() & QQuickViewSection::NextLabelAtEnd) {
        if (!nextSectionItem) {
            nextSectionItem = getSectionItem(nextSection);
        } else if (nextStickySection != nextSection) {
            QDeclarativeContext *context = QDeclarativeEngine::contextForObject(nextSectionItem)->parentContext();
            context->setContextProperty(QLatin1String("section"), nextSection);
        }
        nextStickySection = nextSection;
        if (!nextSectionItem)
            return;

        qreal sectionSize = orient == QQuickListView::Vertical ? nextSectionItem->height() : nextSectionItem->width();
        nextSectionItem->setVisible(!nextSection.isEmpty());
        qreal pos = isRtl ? position() : viewPos + size() - sectionSize;
        if (lastSectionItem) {
            qreal sectionPos = orient == QQuickListView::Vertical ? lastSectionItem->y() : lastSectionItem->x();
            pos = isRtl ? qMin(pos, sectionPos - sectionSize) : qMax(pos, sectionPos + sectionSize);
        }
        if (header)
            pos = isRtl ? qMin(header->endPosition() - sectionSize, pos) : qMax(header->endPosition(), pos);
        if (orient == QQuickListView::Vertical)
            nextSectionItem->setY(pos);
        else
            nextSectionItem->setX(pos);
    } else if (nextSectionItem) {
        releaseSectionItem(nextSectionItem);
        nextSectionItem = 0;
    }
}

void QQuickListViewPrivate::updateSections()
{
    Q_Q(QQuickListView);
    if (!q->isComponentComplete())
        return;

    QQuickItemViewPrivate::updateSections();

    if (sectionCriteria && !visibleItems.isEmpty()) {
        QString prevSection;
        if (visibleIndex > 0)
            prevSection = sectionAt(visibleIndex-1);
        QQuickListViewAttached *prevAtt = 0;
        int idx = -1;
        for (int i = 0; i < visibleItems.count(); ++i) {
            QQuickListViewAttached *attached = static_cast<QQuickListViewAttached*>(visibleItems.at(i)->attached);
            attached->setPrevSection(prevSection);
            if (visibleItems.at(i)->index != -1) {
                QString propValue = model->stringValue(visibleItems.at(i)->index, sectionCriteria->property());
                attached->setSection(sectionCriteria->sectionString(propValue));
                idx = visibleItems.at(i)->index;
            }
            updateInlineSection(static_cast<FxListItemSG*>(visibleItems.at(i)));
            if (prevAtt)
                prevAtt->setNextSection(attached->section());
            prevSection = attached->section();
            prevAtt = attached;
        }
        if (prevAtt) {
            if (idx > 0 && idx < model->count()-1)
                prevAtt->setNextSection(sectionAt(idx+1));
            else
                prevAtt->setNextSection(QString());
        }
    }

    lastVisibleSection = QString();
    updateCurrentSection();
    updateStickySections();
}

void QQuickListViewPrivate::updateCurrentSection()
{
    Q_Q(QQuickListView);
    if (!sectionCriteria || visibleItems.isEmpty()) {
        if (!currentSection.isEmpty()) {
            currentSection.clear();
            emit q->currentSectionChanged();
        }
        return;
    }
    bool inlineSections = sectionCriteria->labelPositioning() & QQuickViewSection::InlineLabels;
    qreal sectionThreshold = position();
    if (currentSectionItem && !inlineSections)
        sectionThreshold += orient == QQuickListView::Vertical ? currentSectionItem->height() : currentSectionItem->width();
    int index = 0;
    int modelIndex = visibleIndex;
    while (index < visibleItems.count() && visibleItems.at(index)->endPosition() <= sectionThreshold) {
        if (visibleItems.at(index)->index != -1)
            modelIndex = visibleItems.at(index)->index;
        ++index;
    }

    QString newSection = currentSection;
    if (index < visibleItems.count())
        newSection = visibleItems.at(index)->attached->section();
    else
        newSection = (*visibleItems.constBegin())->attached->section();
    if (newSection != currentSection) {
        currentSection = newSection;
        updateStickySections();
        emit q->currentSectionChanged();
    }

    if (sectionCriteria->labelPositioning() & QQuickViewSection::NextLabelAtEnd) {
        // Don't want to scan for next section on every movement, so remember
        // the last section in the visible area and only scan for the next
        // section when that changes.  Clearing lastVisibleSection will also
        // force searching.
        QString lastSection = currentSection;
        qreal endPos = isRightToLeft() ? -position() : position() + size();
        if (nextSectionItem && !inlineSections)
            endPos -= orient == QQuickListView::Vertical ? nextSectionItem->height() : nextSectionItem->width();
        while (index < visibleItems.count() && static_cast<FxListItemSG*>(visibleItems.at(index))->itemPosition() < endPos) {
            if (visibleItems.at(index)->index != -1)
                modelIndex = visibleItems.at(index)->index;
            lastSection = visibleItems.at(index)->attached->section();
            ++index;
        }

        if (lastVisibleSection != lastSection) {
            nextSection = QString();
            lastVisibleSection = lastSection;
            for (int i = modelIndex; i < itemCount; ++i) {
                QString section = sectionAt(i);
                if (section != lastSection) {
                    nextSection = section;
                    updateStickySections();
                    break;
                }
            }
        }
    }
}

void QQuickListViewPrivate::initializeCurrentItem()
{
    QQuickItemViewPrivate::initializeCurrentItem();

    if (currentItem) {
        FxListItemSG *listItem = static_cast<FxListItemSG *>(currentItem);

        if (currentIndex == visibleIndex - 1 && visibleItems.count()) {
            // We can calculate exact postion in this case
            listItem->setPosition(visibleItems.first()->position() - currentItem->size() - spacing);
        } else {
            // Create current item now and position as best we can.
            // Its position will be corrected when it becomes visible.
            listItem->setPosition(positionAt(currentIndex));
        }

        // Avoid showing section delegate twice.  We still need the section heading so that
        // currentItem positioning works correctly.
        // This is slightly sub-optimal, but section heading caching minimizes the impact.
        if (listItem->section)
            listItem->section->setVisible(false);

        if (visibleItems.isEmpty())
            averageSize = listItem->size();
    }
}

void QQuickListViewPrivate::updateAverage()
{
    if (!visibleItems.count())
        return;
    qreal sum = 0.0;
    for (int i = 0; i < visibleItems.count(); ++i)
        sum += visibleItems.at(i)->size();
    averageSize = qRound(sum / visibleItems.count());
}

qreal QQuickListViewPrivate::headerSize() const
{
    return header ? header->size() : 0.0;
}

qreal QQuickListViewPrivate::footerSize() const
{
    return footer ? footer->size() : 0.0;
}

bool QQuickListViewPrivate::showHeaderForIndex(int index) const
{
    return index == 0;
}

bool QQuickListViewPrivate::showFooterForIndex(int index) const
{
    return index == model->count()-1;
}

void QQuickListViewPrivate::updateFooter()
{
    Q_Q(QQuickListView);
    bool created = false;
    if (!footer) {
        QQuickItem *item = createComponentItem(footerComponent, true);
        if (!item)
            return;
        item->setZ(1);
        footer = new FxListItemSG(item, q, true);
        created = true;
    }

    FxListItemSG *listItem = static_cast<FxListItemSG*>(footer);
    if (visibleItems.count()) {
        qreal endPos = lastPosition();
        if (findLastVisibleIndex() == model->count()-1) {
            listItem->setPosition(endPos);
        } else {
            qreal visiblePos = position() + q->height();
            if (endPos <= visiblePos || listItem->position() < endPos)
                listItem->setPosition(endPos);
        }
    } else {
        listItem->setPosition(visiblePos);
    }

    if (created)
        emit q->footerItemChanged();
}

void QQuickListViewPrivate::updateHeader()
{
    Q_Q(QQuickListView);
    bool created = false;
    if (!header) {
        QQuickItem *item = createComponentItem(headerComponent, true);
        if (!item)
            return;
        item->setZ(1);
        header = new FxListItemSG(item, q, true);
        created = true;
    }

    FxListItemSG *listItem = static_cast<FxListItemSG*>(header);
    if (listItem) {
        if (visibleItems.count()) {
            qreal startPos = originPosition();
            if (visibleIndex == 0) {
                listItem->setPosition(startPos - headerSize());
            } else {
                if (position() <= startPos || listItem->position() > startPos - headerSize())
                    listItem->setPosition(startPos - headerSize());
            }
        } else {
            listItem->setPosition(-headerSize());
        }
    }

    if (created)
        emit q->headerItemChanged();
}

void QQuickListViewPrivate::itemGeometryChanged(QQuickItem *item, const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_Q(QQuickListView);
    QQuickItemViewPrivate::itemGeometryChanged(item, newGeometry, oldGeometry);
    if (!q->isComponentComplete())
        return;
    if (item != contentItem && (!highlight || item != highlight->item)) {
        if ((orient == QQuickListView::Vertical && newGeometry.height() != oldGeometry.height())
            || (orient == QQuickListView::Horizontal && newGeometry.width() != oldGeometry.width())) {
            forceLayout = true;
            q->polish();
        }
    }
}

void QQuickListViewPrivate::fixupPosition()
{
    if ((haveHighlightRange && highlightRange == QQuickListView::StrictlyEnforceRange)
        || snapMode != QQuickListView::NoSnap)
        moveReason = Other;
    if (orient == QQuickListView::Vertical)
        fixupY();
    else
        fixupX();
}

void QQuickListViewPrivate::fixup(AxisData &data, qreal minExtent, qreal maxExtent)
{
    if ((orient == QQuickListView::Horizontal && &data == &vData)
        || (orient == QQuickListView::Vertical && &data == &hData))
        return;

    correctFlick = false;
    fixupMode = moveReason == Mouse ? fixupMode : Immediate;
    bool strictHighlightRange = haveHighlightRange && highlightRange == QQuickListView::StrictlyEnforceRange;

    qreal viewPos = isRightToLeft() ? -position()-size() : position();

    if (snapMode != QQuickListView::NoSnap && moveReason != QQuickListViewPrivate::SetIndex) {
        qreal tempPosition = isRightToLeft() ? -position()-size() : position();
        if (snapMode == QQuickListView::SnapOneItem && moveReason == Mouse) {
            // if we've been dragged < averageSize/2 then bias towards the next item
            qreal dist = data.move.value() - (data.pressPos - data.dragStartOffset);
            qreal bias = 0;
            if (data.velocity > 0 && dist > QML_FLICK_SNAPONETHRESHOLD && dist < averageSize/2)
                bias = averageSize/2;
            else if (data.velocity < 0 && dist < -QML_FLICK_SNAPONETHRESHOLD && dist > -averageSize/2)
                bias = -averageSize/2;
            if (isRightToLeft())
                bias = -bias;
            tempPosition -= bias;
        }
        FxViewItem *topItem = snapItemAt(tempPosition+highlightRangeStart);
        if (!topItem && strictHighlightRange && currentItem) {
            // StrictlyEnforceRange always keeps an item in range
            updateHighlight();
            topItem = currentItem;
        }
        FxViewItem *bottomItem = snapItemAt(tempPosition+highlightRangeEnd);
        if (!bottomItem && strictHighlightRange && currentItem) {
            // StrictlyEnforceRange always keeps an item in range
            updateHighlight();
            bottomItem = currentItem;
        }
        qreal pos;
        bool isInBounds = -position() > maxExtent && -position() <= minExtent;
        if (topItem && (isInBounds || strictHighlightRange)) {
            if (topItem->index == 0 && header && tempPosition+highlightRangeStart < header->position()+header->size()/2 && !strictHighlightRange) {
                pos = isRightToLeft() ? - header->position() + highlightRangeStart - size() : header->position() - highlightRangeStart;
            } else {
                if (isRightToLeft())
                    pos = qMax(qMin(-topItem->position() + highlightRangeStart - size(), -maxExtent), -minExtent);
                else
                    pos = qMax(qMin(topItem->position() - highlightRangeStart, -maxExtent), -minExtent);
            }
        } else if (bottomItem && isInBounds) {
            if (isRightToLeft())
                pos = qMax(qMin(-bottomItem->position() + highlightRangeEnd - size(), -maxExtent), -minExtent);
            else
                pos = qMax(qMin(bottomItem->position() - highlightRangeEnd, -maxExtent), -minExtent);
        } else {
            QQuickItemViewPrivate::fixup(data, minExtent, maxExtent);
            return;
        }

        qreal dist = qAbs(data.move + pos);
        if (dist > 0) {
            timeline.reset(data.move);
            if (fixupMode != Immediate) {
                timeline.move(data.move, -pos, QEasingCurve(QEasingCurve::InOutQuad), fixupDuration/2);
                data.fixingUp = true;
            } else {
                timeline.set(data.move, -pos);
            }
            vTime = timeline.time();
        }
    } else if (currentItem && strictHighlightRange && moveReason != QQuickListViewPrivate::SetIndex) {
        updateHighlight();
        qreal pos = static_cast<FxListItemSG*>(currentItem)->itemPosition();
        if (viewPos < pos + static_cast<FxListItemSG*>(currentItem)->itemSize() - highlightRangeEnd)
            viewPos = pos + static_cast<FxListItemSG*>(currentItem)->itemSize() - highlightRangeEnd;
        if (viewPos > pos - highlightRangeStart)
            viewPos = pos - highlightRangeStart;
        if (isRightToLeft())
            viewPos = -viewPos-size();

        timeline.reset(data.move);
        if (viewPos != position()) {
            if (fixupMode != Immediate) {
                timeline.move(data.move, -viewPos, QEasingCurve(QEasingCurve::InOutQuad), fixupDuration/2);
                data.fixingUp = true;
            } else {
                timeline.set(data.move, -viewPos);
            }
        }
        vTime = timeline.time();
    } else {
        QQuickItemViewPrivate::fixup(data, minExtent, maxExtent);
    }
    data.inOvershoot = false;
    fixupMode = Normal;
}

void QQuickListViewPrivate::flick(AxisData &data, qreal minExtent, qreal maxExtent, qreal vSize,
                                        QDeclarativeTimeLineCallback::Callback fixupCallback, qreal velocity)
{
    Q_Q(QQuickListView);

    data.fixingUp = false;
    moveReason = Mouse;
    if ((!haveHighlightRange || highlightRange != QQuickListView::StrictlyEnforceRange) && snapMode == QQuickListView::NoSnap) {
        correctFlick = true;
        QQuickItemViewPrivate::flick(data, minExtent, maxExtent, vSize, fixupCallback, velocity);
        return;
    }
    qreal maxDistance = 0;
    qreal dataValue = isRightToLeft() ? -data.move.value()+size() : data.move.value();

    // -ve velocity means list is moving up/left
    if (velocity > 0) {
        if (data.move.value() < minExtent) {
            if (snapMode == QQuickListView::SnapOneItem && !hData.flicking && !vData.flicking) {
                // if we've been dragged < averageSize/2 then bias towards the next item
                qreal dist = data.move.value() - (data.pressPos - data.dragStartOffset);
                qreal bias = dist < averageSize/2 ? averageSize/2 : 0;
                if (isRightToLeft())
                    bias = -bias;
                data.flickTarget = -snapPosAt(-(dataValue - highlightRangeStart) - bias) + highlightRangeStart;
                maxDistance = qAbs(data.flickTarget - data.move.value());
                velocity = maxVelocity;
            } else {
                maxDistance = qAbs(minExtent - data.move.value());
            }
        }
        if (snapMode == QQuickListView::NoSnap && highlightRange != QQuickListView::StrictlyEnforceRange)
            data.flickTarget = minExtent;
    } else {
        if (data.move.value() > maxExtent) {
            if (snapMode == QQuickListView::SnapOneItem && !hData.flicking && !vData.flicking) {
                // if we've been dragged < averageSize/2 then bias towards the next item
                qreal dist = data.move.value() - (data.pressPos - data.dragStartOffset);
                qreal bias = -dist < averageSize/2 ? averageSize/2 : 0;
                if (isRightToLeft())
                    bias = -bias;
                data.flickTarget = -snapPosAt(-(dataValue - highlightRangeStart) + bias) + highlightRangeStart;
                maxDistance = qAbs(data.flickTarget - data.move.value());
                velocity = -maxVelocity;
            } else {
                maxDistance = qAbs(maxExtent - data.move.value());
            }
        }
        if (snapMode == QQuickListView::NoSnap && highlightRange != QQuickListView::StrictlyEnforceRange)
            data.flickTarget = maxExtent;
    }
    bool overShoot = boundsBehavior == QQuickFlickable::DragAndOvershootBounds;
    if (maxDistance > 0 || overShoot) {
        // These modes require the list to stop exactly on an item boundary.
        // The initial flick will estimate the boundary to stop on.
        // Since list items can have variable sizes, the boundary will be
        // reevaluated and adjusted as we approach the boundary.
        qreal v = velocity;
        if (maxVelocity != -1 && maxVelocity < qAbs(v)) {
            if (v < 0)
                v = -maxVelocity;
            else
                v = maxVelocity;
        }
        if (!hData.flicking && !vData.flicking) {
            // the initial flick - estimate boundary
            qreal accel = deceleration;
            qreal v2 = v * v;
            overshootDist = 0.0;
            // + averageSize/4 to encourage moving at least one item in the flick direction
            qreal dist = v2 / (accel * 2.0) + averageSize/4;
            if (maxDistance > 0)
                dist = qMin(dist, maxDistance);
            if (v > 0)
                dist = -dist;
            if ((maxDistance > 0.0 && v2 / (2.0f * maxDistance) < accel) || snapMode == QQuickListView::SnapOneItem) {
                if (snapMode != QQuickListView::SnapOneItem) {
                    qreal distTemp = isRightToLeft() ? -dist : dist;
                    data.flickTarget = -snapPosAt(-(dataValue - highlightRangeStart) + distTemp) + highlightRangeStart;
                }
                data.flickTarget = isRightToLeft() ? -data.flickTarget+size() : data.flickTarget;
                if (overShoot) {
                    if (data.flickTarget >= minExtent) {
                        overshootDist = overShootDistance(vSize);
                        data.flickTarget += overshootDist;
                    } else if (data.flickTarget <= maxExtent) {
                        overshootDist = overShootDistance(vSize);
                        data.flickTarget -= overshootDist;
                    }
                }
                qreal adjDist = -data.flickTarget + data.move.value();
                if (qAbs(adjDist) > qAbs(dist)) {
                    // Prevent painfully slow flicking - adjust velocity to suit flickDeceleration
                    qreal adjv2 = accel * 2.0f * qAbs(adjDist);
                    if (adjv2 > v2) {
                        v2 = adjv2;
                        v = qSqrt(v2);
                        if (dist > 0)
                            v = -v;
                    }
                }
                dist = adjDist;
                accel = v2 / (2.0f * qAbs(dist));
            } else if (overShoot) {
                data.flickTarget = data.move.value() - dist;
                if (data.flickTarget >= minExtent) {
                    overshootDist = overShootDistance(vSize);
                    data.flickTarget += overshootDist;
                } else if (data.flickTarget <= maxExtent) {
                    overshootDist = overShootDistance(vSize);
                    data.flickTarget -= overshootDist;
                }
            }
            timeline.reset(data.move);
            timeline.accel(data.move, v, accel, maxDistance + overshootDist);
            timeline.callback(QDeclarativeTimeLineCallback(&data.move, fixupCallback, this));
            if (!hData.flicking && q->xflick()) {
                hData.flicking = true;
                emit q->flickingChanged();
                emit q->flickingHorizontallyChanged();
                emit q->flickStarted();
            }
            if (!vData.flicking && q->yflick()) {
                vData.flicking = true;
                emit q->flickingChanged();
                emit q->flickingVerticallyChanged();
                emit q->flickStarted();
            }
            correctFlick = true;
        } else {
            // reevaluate the target boundary.
            qreal newtarget = data.flickTarget;
            if (snapMode != QQuickListView::NoSnap || highlightRange == QQuickListView::StrictlyEnforceRange) {
                qreal tempFlickTarget = isRightToLeft() ? -data.flickTarget+size() : data.flickTarget;
                newtarget = -snapPosAt(-(tempFlickTarget - highlightRangeStart)) + highlightRangeStart;
                newtarget = isRightToLeft() ? -newtarget+size() : newtarget;
            }
            if (velocity < 0 && newtarget <= maxExtent)
                newtarget = maxExtent - overshootDist;
            else if (velocity > 0 && newtarget >= minExtent)
                newtarget = minExtent + overshootDist;
            if (newtarget == data.flickTarget) { // boundary unchanged - nothing to do
                if (qAbs(velocity) < MinimumFlickVelocity)
                    correctFlick = false;
                return;
            }
            data.flickTarget = newtarget;
            qreal dist = -newtarget + data.move.value();
            if ((v < 0 && dist < 0) || (v > 0 && dist > 0)) {
                correctFlick = false;
                timeline.reset(data.move);
                fixup(data, minExtent, maxExtent);
                return;
            }
            timeline.reset(data.move);
            timeline.accelDistance(data.move, v, -dist);
            timeline.callback(QDeclarativeTimeLineCallback(&data.move, fixupCallback, this));
        }
    } else {
        correctFlick = false;
        timeline.reset(data.move);
        fixup(data, minExtent, maxExtent);
    }
}

//----------------------------------------------------------------------------

/*!
    \qmlclass ListView QQuickListView
    \inqmlmodule QtQuick 2
    \ingroup qml-view-elements
    \inherits Flickable
    \brief The ListView item provides a list view of items provided by a model.

    A ListView displays data from models created from built-in QML elements like ListModel
    and XmlListModel, or custom model classes defined in C++ that inherit from
    QAbstractListModel.

    A ListView has a \l model, which defines the data to be displayed, and
    a \l delegate, which defines how the data should be displayed. Items in a
    ListView are laid out horizontally or vertically. List views are inherently
    flickable because ListView inherits from \l Flickable.

    \section1 Example Usage

    The following example shows the definition of a simple list model defined
    in a file called \c ContactModel.qml:

    \snippet doc/src/snippets/declarative/listview/ContactModel.qml 0

    Another component can display this model data in a ListView, like this:

    \snippet doc/src/snippets/declarative/listview/listview.qml import
    \codeline
    \snippet doc/src/snippets/declarative/listview/listview.qml classdocs simple

    \image listview-simple.png

    Here, the ListView creates a \c ContactModel component for its model, and a \l Text element
    for its delegate. The view will create a new \l Text component for each item in the model. Notice
    the delegate is able to access the model's \c name and \c number data directly.

    An improved list view is shown below. The delegate is visually improved and is moved
    into a separate \c contactDelegate component.

    \snippet doc/src/snippets/declarative/listview/listview.qml classdocs advanced
    \image listview-highlight.png

    The currently selected item is highlighted with a blue \l Rectangle using the \l highlight property,
    and \c focus is set to \c true to enable keyboard navigation for the list view.
    The list view itself is a focus scope (see \l{qmlfocus#Acquiring Focus and Focus Scopes}{the focus documentation page} for more details).

    Delegates are instantiated as needed and may be destroyed at any time.
    State should \e never be stored in a delegate.

    ListView attaches a number of properties to the root item of the delegate, for example
    \c {ListView.isCurrentItem}.  In the following example, the root delegate item can access
    this attached property directly as \c ListView.isCurrentItem, while the child
    \c contactInfo object must refer to this property as \c wrapper.ListView.isCurrentItem.

    \snippet doc/src/snippets/declarative/listview/listview.qml isCurrentItem

    \note Views do not enable \e clip automatically.  If the view
    is not clipped by another item or the screen, it will be necessary
    to set \e {clip: true} in order to have the out of view items clipped
    nicely.

    \sa {QML Data Models}, GridView, {declarative/modelviews/listview}{ListView examples}
*/
QQuickListView::QQuickListView(QQuickItem *parent)
    : QQuickItemView(*(new QQuickListViewPrivate), parent)
{
}

QQuickListView::~QQuickListView()
{
}

/*!
    \qmlattachedproperty bool QtQuick2::ListView::isCurrentItem
    This attached property is true if this delegate is the current item; otherwise false.

    It is attached to each instance of the delegate.

    This property may be used to adjust the appearance of the current item, for example:

    \snippet doc/src/snippets/declarative/listview/listview.qml isCurrentItem
*/

/*!
    \qmlattachedproperty ListView QtQuick2::ListView::view
    This attached property holds the view that manages this delegate instance.

    It is attached to each instance of the delegate.
*/

/*!
    \qmlattachedproperty string QtQuick2::ListView::previousSection
    This attached property holds the section of the previous element.

    It is attached to each instance of the delegate.

    The section is evaluated using the \l {ListView::section.property}{section} properties.
*/

/*!
    \qmlattachedproperty string QtQuick2::ListView::nextSection
    This attached property holds the section of the next element.

    It is attached to each instance of the delegate.

    The section is evaluated using the \l {ListView::section.property}{section} properties.
*/

/*!
    \qmlattachedproperty string QtQuick2::ListView::section
    This attached property holds the section of this element.

    It is attached to each instance of the delegate.

    The section is evaluated using the \l {ListView::section.property}{section} properties.
*/

/*!
    \qmlattachedproperty bool QtQuick2::ListView::delayRemove
    This attached property holds whether the delegate may be destroyed.

    It is attached to each instance of the delegate.

    It is sometimes necessary to delay the destruction of an item
    until an animation completes.

    The example delegate below ensures that the animation completes before
    the item is removed from the list.

    \snippet doc/src/snippets/declarative/listview/listview.qml delayRemove
*/

/*!
    \qmlattachedsignal QtQuick2::ListView::onAdd()
    This attached handler is called immediately after an item is added to the view.
*/

/*!
    \qmlattachedsignal QtQuick2::ListView::onRemove()
    This attached handler is called immediately before an item is removed from the view.
*/

/*!
    \qmlproperty model QtQuick2::ListView::model
    This property holds the model providing data for the list.

    The model provides the set of data that is used to create the items
    in the view. Models can be created directly in QML using \l ListModel, \l XmlListModel
    or \l VisualItemModel, or provided by C++ model classes. If a C++ model class is
    used, it must be a subclass of \l QAbstractItemModel or a simple list.

    \sa {qmlmodels}{Data Models}
*/

/*!
    \qmlproperty Component QtQuick2::ListView::delegate

    The delegate provides a template defining each item instantiated by the view.
    The index is exposed as an accessible \c index property.  Properties of the
    model are also available depending upon the type of \l {qmlmodels}{Data Model}.

    The number of elements in the delegate has a direct effect on the
    flicking performance of the view.  If at all possible, place functionality
    that is not needed for the normal display of the delegate in a \l Loader which
    can load additional elements when needed.

    The ListView will lay out the items based on the size of the root item
    in the delegate.

    It is recommended that the delegate's size be a whole number to avoid sub-pixel
    alignment of items.

    \note Delegates are instantiated as needed and may be destroyed at any time.
    State should \e never be stored in a delegate.
*/
/*!
    \qmlproperty int QtQuick2::ListView::currentIndex
    \qmlproperty Item QtQuick2::ListView::currentItem

    The \c currentIndex property holds the index of the current item, and
    \c currentItem holds the current item.   Setting the currentIndex to -1
    will clear the highlight and set currentItem to null.

    If highlightFollowsCurrentItem is \c true, setting either of these
    properties will smoothly scroll the ListView so that the current
    item becomes visible.

    Note that the position of the current item
    may only be approximate until it becomes visible in the view.
*/

/*!
  \qmlproperty Item QtQuick2::ListView::highlightItem

    This holds the highlight item created from the \l highlight component.

  The \c highlightItem is managed by the view unless
  \l highlightFollowsCurrentItem is set to false.

  \sa highlight, highlightFollowsCurrentItem
*/

/*!
  \qmlproperty int QtQuick2::ListView::count
  This property holds the number of items in the view.
*/

/*!
    \qmlproperty Component QtQuick2::ListView::highlight
    This property holds the component to use as the highlight.

    An instance of the highlight component is created for each list.
    The geometry of the resulting component instance is managed by the list
    so as to stay with the current item, unless the highlightFollowsCurrentItem
    property is false.

    \sa highlightItem, highlightFollowsCurrentItem, {declarative/modelviews/listview}{ListView examples}
*/

/*!
    \qmlproperty bool QtQuick2::ListView::highlightFollowsCurrentItem
    This property holds whether the highlight is managed by the view.

    If this property is true (the default value), the highlight is moved smoothly
    to follow the current item.  Otherwise, the
    highlight is not moved by the view, and any movement must be implemented
    by the highlight.

    Here is a highlight with its motion defined by a \l {SpringAnimation} item:

    \snippet doc/src/snippets/declarative/listview/listview.qml highlightFollowsCurrentItem

    Note that the highlight animation also affects the way that the view
    is scrolled.  This is because the view moves to maintain the
    highlight within the preferred highlight range (or visible viewport).

    \sa highlight, highlightMoveSpeed
*/
//###Possibly rename these properties, since they are very useful even without a highlight?
/*!
    \qmlproperty real QtQuick2::ListView::preferredHighlightBegin
    \qmlproperty real QtQuick2::ListView::preferredHighlightEnd
    \qmlproperty enumeration QtQuick2::ListView::highlightRangeMode

    These properties define the preferred range of the highlight (for the current item)
    within the view. The \c preferredHighlightBegin value must be less than the
    \c preferredHighlightEnd value.

    These properties affect the position of the current item when the list is scrolled.
    For example, if the currently selected item should stay in the middle of the
    list when the view is scrolled, set the \c preferredHighlightBegin and
    \c preferredHighlightEnd values to the top and bottom coordinates of where the middle
    item would be. If the \c currentItem is changed programmatically, the list will
    automatically scroll so that the current item is in the middle of the view.
    Furthermore, the behavior of the current item index will occur whether or not a
    highlight exists.

    Valid values for \c highlightRangeMode are:

    \list
    \o ListView.ApplyRange - the view attempts to maintain the highlight within the range.
       However, the highlight can move outside of the range at the ends of the list or due
       to mouse interaction.
    \o ListView.StrictlyEnforceRange - the highlight never moves outside of the range.
       The current item changes if a keyboard or mouse action would cause the highlight to move
       outside of the range.
    \o ListView.NoHighlightRange - this is the default value.
    \endlist
*/
void QQuickListView::setHighlightFollowsCurrentItem(bool autoHighlight)
{
    Q_D(QQuickListView);
    if (d->autoHighlight != autoHighlight) {
        if (!autoHighlight) {
            if (d->highlightPosAnimator)
                d->highlightPosAnimator->stop();
            if (d->highlightSizeAnimator)
                d->highlightSizeAnimator->stop();
        }
        QQuickItemView::setHighlightFollowsCurrentItem(autoHighlight);
    }
}

/*!
    \qmlproperty real QtQuick2::ListView::spacing

    This property holds the spacing between items.

    The default value is 0.
*/
qreal QQuickListView::spacing() const
{
    Q_D(const QQuickListView);
    return d->spacing;
}

void QQuickListView::setSpacing(qreal spacing)
{
    Q_D(QQuickListView);
    if (spacing != d->spacing) {
        d->spacing = spacing;
        d->forceLayout = true;
        polish();
        emit spacingChanged();
    }
}

/*!
    \qmlproperty enumeration QtQuick2::ListView::orientation
    This property holds the orientation of the list.

    Possible values:

    \list
    \o ListView.Horizontal - Items are laid out horizontally
    \o ListView.Vertical (default) - Items are laid out vertically
    \endlist

    \table
    \row
    \o Horizontal orientation:
    \image ListViewHorizontal.png

    \row
    \o Vertical orientation:
    \image listview-highlight.png
    \endtable
*/
QQuickListView::Orientation QQuickListView::orientation() const
{
    Q_D(const QQuickListView);
    return d->orient;
}

void QQuickListView::setOrientation(QQuickListView::Orientation orientation)
{
    Q_D(QQuickListView);
    if (d->orient != orientation) {
        d->orient = orientation;
        if (d->orient == Vertical) {
            setContentWidth(-1);
            setFlickableDirection(VerticalFlick);
            setContentX(0);
        } else {
            setContentHeight(-1);
            setFlickableDirection(HorizontalFlick);
            setContentY(0);
        }
        d->regenerate();
        emit orientationChanged();
    }
}

/*!
  \qmlproperty enumeration QtQuick2::ListView::layoutDirection
  This property holds the layout direction of the horizontal list.

  Possible values:

  \list
  \o Qt.LeftToRight (default) - Items will be laid out from left to right.
  \o Qt.RightToLeft - Items will be laid out from right to let.
  \endlist

  \sa ListView::effectiveLayoutDirection
*/


/*!
    \qmlproperty enumeration QtQuick2::ListView::effectiveLayoutDirection
    This property holds the effective layout direction of the horizontal list.

    When using the attached property \l {LayoutMirroring::enabled}{LayoutMirroring::enabled} for locale layouts,
    the visual layout direction of the horizontal list will be mirrored. However, the
    property \l {ListView::layoutDirection}{layoutDirection} will remain unchanged.

    \sa ListView::layoutDirection, {LayoutMirroring}{LayoutMirroring}
*/

/*!
    \qmlproperty bool QtQuick2::ListView::keyNavigationWraps
    This property holds whether the list wraps key navigation.

    If this is true, key navigation that would move the current item selection
    past the end of the list instead wraps around and moves the selection to
    the start of the list, and vice-versa.

    By default, key navigation is not wrapped.
*/


/*!
    \qmlproperty int QtQuick2::ListView::cacheBuffer
    This property determines whether delegates are retained outside the
    visible area of the view.

    If this value is non-zero, the view may keep as many delegates
    instantiated as it can fit within the buffer specified.  For example,
    if in a vertical view the delegate is 20 pixels high and \c cacheBuffer is
    set to 40, then up to 2 delegates above and 2 delegates below the visible
    area may be created/retained.  The buffered delegates are created asynchronously,
    allowing creation to occur across multiple frames and reducing the
    likelihood of skipping frames.  In order to improve painting performance
    delegates outside the visible area have their \l visible property set to
    false until they are moved into the visible area.

    Note that cacheBuffer is not a pixel buffer - it only maintains additional
    instantiated delegates.

    Setting this value can improve the smoothness of scrolling behavior at the expense
    of additional memory usage.  It is not a substitute for creating efficient
    delegates; the fewer elements in a delegate, the faster a view can be
    scrolled.
*/


/*!
    \qmlproperty string QtQuick2::ListView::section.property
    \qmlproperty enumeration QtQuick2::ListView::section.criteria
    \qmlproperty Component QtQuick2::ListView::section.delegate
    \qmlproperty enumeration QtQuick2::ListView::section.labelPositioning

    These properties determine the expression to be evaluated and appearance
    of the section labels.

    \c section.property holds the name of the property that is the basis
    of each section.

    \c section.criteria holds the criteria for forming each section based on
    \c section.property. This value can be one of:

    \list
    \o ViewSection.FullString (default) - sections are created based on the
    \c section.property value.
    \o ViewSection.FirstCharacter - sections are created based on the first
    character of the \c section.property value (for example, 'A', 'B', 'C'
    sections, etc. for an address book)
    \endlist

    \c section.delegate holds the delegate component for each section.

    \c section.labelPositioning determines whether the current and/or
    next section labels stick to the start/end of the view, and whether
    the labels are shown inline.  This value can be a combination of:

    \list
    \o ViewSection.InlineLabels - section labels are shown inline between
    the item delegates separating sections (default).
    \o ViewSection.CurrentLabelAtStart - the current section label sticks to the
    start of the view as it is moved.
    \o ViewSection.NextLabelAtEnd - the next section label (beyond all visible
    sections) sticks to the end of the view as it is moved. \note Enabling
    \c ViewSection.NextLabelAtEnd requires the view to scan ahead for the next
    section, which has performance implications, especially for slower models.
    \endlist

    Each item in the list has attached properties named \c ListView.section,
    \c ListView.previousSection and \c ListView.nextSection.

    For example, here is a ListView that displays a list of animals, separated
    into sections. Each item in the ListView is placed in a different section
    depending on the "size" property of the model item. The \c sectionHeading
    delegate component provides the light blue bar that marks the beginning of
    each section.


    \snippet examples/declarative/modelviews/listview/sections.qml 0

    \image qml-listview-sections-example.png

    \note Adding sections to a ListView does not automatically re-order the
    list items by the section criteria.
    If the model is not ordered by section, then it is possible that
    the sections created will not be unique; each boundary between
    differing sections will result in a section header being created
    even if that section exists elsewhere.

    \sa {declarative/modelviews/listview}{ListView examples}
*/
QQuickViewSection *QQuickListView::sectionCriteria()
{
    Q_D(QQuickListView);
    if (!d->sectionCriteria) {
        d->sectionCriteria = new QQuickViewSection(this);
        connect(d->sectionCriteria, SIGNAL(propertyChanged()), this, SLOT(updateSections()));
    }
    return d->sectionCriteria;
}

/*!
    \qmlproperty string QtQuick2::ListView::currentSection
    This property holds the section that is currently at the beginning of the view.
*/
QString QQuickListView::currentSection() const
{
    Q_D(const QQuickListView);
    return d->currentSection;
}

/*!
    \qmlproperty real QtQuick2::ListView::highlightMoveSpeed
    \qmlproperty int QtQuick2::ListView::highlightMoveDuration
    \qmlproperty real QtQuick2::ListView::highlightResizeSpeed
    \qmlproperty int QtQuick2::ListView::highlightResizeDuration

    These properties hold the move and resize animation speed of the highlight delegate.

    \l highlightFollowsCurrentItem must be true for these properties
    to have effect.

    The default value for the speed properties is 400 pixels/second.
    The default value for the duration properties is -1, i.e. the
    highlight will take as much time as necessary to move at the set speed.

    These properties have the same characteristics as a SmoothedAnimation.

    \sa highlightFollowsCurrentItem
*/
qreal QQuickListView::highlightMoveSpeed() const
{
    Q_D(const QQuickListView);
    return d->highlightMoveSpeed;
}

void QQuickListView::setHighlightMoveSpeed(qreal speed)
{
    Q_D(QQuickListView);
    if (d->highlightMoveSpeed != speed) {
        d->highlightMoveSpeed = speed;
        if (d->highlightPosAnimator)
            d->highlightPosAnimator->velocity = d->highlightMoveSpeed;
        emit highlightMoveSpeedChanged();
    }
}

void QQuickListView::setHighlightMoveDuration(int duration)
{
    Q_D(QQuickListView);
    if (d->highlightMoveDuration != duration) {
        if (d->highlightPosAnimator)
            d->highlightPosAnimator->userDuration = duration;
        QQuickItemView::setHighlightMoveDuration(duration);
    }
}

qreal QQuickListView::highlightResizeSpeed() const
{
    Q_D(const QQuickListView);
    return d->highlightResizeSpeed;
}

void QQuickListView::setHighlightResizeSpeed(qreal speed)
{
    Q_D(QQuickListView);
    if (d->highlightResizeSpeed != speed) {
        d->highlightResizeSpeed = speed;
        if (d->highlightSizeAnimator)
            d->highlightSizeAnimator->velocity = d->highlightResizeSpeed;
        emit highlightResizeSpeedChanged();
    }
}

int QQuickListView::highlightResizeDuration() const
{
    Q_D(const QQuickListView);
    return d->highlightResizeDuration;
}

void QQuickListView::setHighlightResizeDuration(int duration)
{
    Q_D(QQuickListView);
    if (d->highlightResizeDuration != duration) {
        d->highlightResizeDuration = duration;
        if (d->highlightSizeAnimator)
            d->highlightSizeAnimator->userDuration = d->highlightResizeDuration;
        emit highlightResizeDurationChanged();
    }
}

/*!
    \qmlproperty enumeration QtQuick2::ListView::snapMode

    This property determines how the view scrolling will settle following a drag or flick.
    The possible values are:

    \list
    \o ListView.NoSnap (default) - the view stops anywhere within the visible area.
    \o ListView.SnapToItem - the view settles with an item aligned with the start of
    the view.
    \o ListView.SnapOneItem - the view settles no more than one item away from the first
    visible item at the time the mouse button is released.  This mode is particularly
    useful for moving one page at a time.
    \endlist

    \c snapMode does not affect the \l currentIndex.  To update the
    \l currentIndex as the list is moved, set \l highlightRangeMode
    to \c ListView.StrictlyEnforceRange.

    \sa highlightRangeMode
*/
QQuickListView::SnapMode QQuickListView::snapMode() const
{
    Q_D(const QQuickListView);
    return d->snapMode;
}

void QQuickListView::setSnapMode(SnapMode mode)
{
    Q_D(QQuickListView);
    if (d->snapMode != mode) {
        d->snapMode = mode;
        emit snapModeChanged();
    }
}


/*!
    \qmlproperty Component QtQuick2::ListView::footer
    This property holds the component to use as the footer.

    An instance of the footer component is created for each view.  The
    footer is positioned at the end of the view, after any items.

    \sa header, footerItem
*/


/*!
    \qmlproperty Component QtQuick2::ListView::header
    This property holds the component to use as the header.

    An instance of the header component is created for each view.  The
    header is positioned at the beginning of the view, before any items.

    \sa footer, headertem
*/

/*!
    \qmlproperty Item QtQuick2::ListView::headerItem
    This holds the header item created from the \l header component.

    An instance of the header component is created for each view.  The
    header is positioned at the beginning of the view, before any items.

    \sa header, footerItem
*/

/*!
    \qmlproperty Item QtQuick2::ListView::footerItem
    This holds the footer item created from the \l footer component.

    An instance of the footer component is created for each view.  The
    footer is positioned at the end of the view, after any items.

    \sa footer, headerItem
*/

void QQuickListView::viewportMoved()
{
    Q_D(QQuickListView);
    QQuickItemView::viewportMoved();
    if (!d->itemCount)
        return;
    // Recursion can occur due to refill changing the content size.
    if (d->inViewportMoved)
        return;
    d->inViewportMoved = true;

    if (yflick())
        d->bufferMode = d->vData.smoothVelocity < 0 ? QQuickListViewPrivate::BufferBefore : QQuickListViewPrivate::BufferAfter;
    else if (d->isRightToLeft())
        d->bufferMode = d->hData.smoothVelocity < 0 ? QQuickListViewPrivate::BufferAfter : QQuickListViewPrivate::BufferBefore;
    else
        d->bufferMode = d->hData.smoothVelocity < 0 ? QQuickListViewPrivate::BufferBefore : QQuickListViewPrivate::BufferAfter;

    d->refill();

    // Set visibility of items to eliminate cost of items outside the visible area.
    qreal from = d->isContentFlowReversed() ? -d->position()-d->size() : d->position();
    qreal to = d->isContentFlowReversed() ? -d->position() : d->position()+d->size();
    for (int i = 0; i < d->visibleItems.count(); ++i) {
        FxViewItem *item = static_cast<FxListItemSG*>(d->visibleItems.at(i));
        item->item->setVisible(item->endPosition() >= from && item->position() <= to);
    }

    if (d->hData.flicking || d->vData.flicking || d->hData.moving || d->vData.moving)
        d->moveReason = QQuickListViewPrivate::Mouse;
    if (d->moveReason != QQuickListViewPrivate::SetIndex) {
        if (d->haveHighlightRange && d->highlightRange == StrictlyEnforceRange && d->highlight) {
            // reposition highlight
            qreal pos = d->highlight->position();
            qreal viewPos = d->isRightToLeft() ? -d->position()-d->size() : d->position();
            if (pos > viewPos + d->highlightRangeEnd - d->highlight->size())
                pos = viewPos + d->highlightRangeEnd - d->highlight->size();
            if (pos < viewPos + d->highlightRangeStart)
                pos = viewPos + d->highlightRangeStart;
            if (pos != d->highlight->position()) {
                d->highlightPosAnimator->stop();
                static_cast<FxListItemSG*>(d->highlight)->setPosition(pos);
            } else {
                d->updateHighlight();
            }

            // update current index
            if (FxViewItem *snapItem = d->snapItemAt(d->highlight->position())) {
                if (snapItem->index >= 0 && snapItem->index != d->currentIndex)
                    d->updateCurrent(snapItem->index);
            }
        }
    }

    if ((d->hData.flicking || d->vData.flicking) && d->correctFlick && !d->inFlickCorrection) {
        d->inFlickCorrection = true;
        // Near an end and it seems that the extent has changed?
        // Recalculate the flick so that we don't end up in an odd position.
        if (yflick() && !d->vData.inOvershoot) {
            if (d->vData.velocity > 0) {
                const qreal minY = minYExtent();
                if ((minY - d->vData.move.value() < height()/2 || d->vData.flickTarget - d->vData.move.value() < height()/2)
                    && minY != d->vData.flickTarget)
                    d->flickY(-d->vData.smoothVelocity.value());
            } else if (d->vData.velocity < 0) {
                const qreal maxY = maxYExtent();
                if ((d->vData.move.value() - maxY < height()/2 || d->vData.move.value() - d->vData.flickTarget < height()/2)
                    && maxY != d->vData.flickTarget)
                    d->flickY(-d->vData.smoothVelocity.value());
            }
        }

        if (xflick() && !d->hData.inOvershoot) {
            if (d->hData.velocity > 0) {
                const qreal minX = minXExtent();
                if ((minX - d->hData.move.value() < width()/2 || d->hData.flickTarget - d->hData.move.value() < width()/2)
                    && minX != d->hData.flickTarget)
                    d->flickX(-d->hData.smoothVelocity.value());
            } else if (d->hData.velocity < 0) {
                const qreal maxX = maxXExtent();
                if ((d->hData.move.value() - maxX < width()/2 || d->hData.move.value() - d->hData.flickTarget < width()/2)
                    && maxX != d->hData.flickTarget)
                    d->flickX(-d->hData.smoothVelocity.value());
            }
        }
        d->inFlickCorrection = false;
    }
    if (d->sectionCriteria) {
        d->updateCurrentSection();
        d->updateStickySections();
    }
    d->inViewportMoved = false;
}

void QQuickListView::keyPressEvent(QKeyEvent *event)
{
    Q_D(QQuickListView);
    if (d->model && d->model->count() && d->interactive) {
        if ((d->orient == QQuickListView::Horizontal && !d->isRightToLeft() && event->key() == Qt::Key_Left)
                    || (d->orient == QQuickListView::Horizontal && d->isRightToLeft() && event->key() == Qt::Key_Right)
                    || (d->orient == QQuickListView::Vertical && event->key() == Qt::Key_Up)) {
            if (currentIndex() > 0 || (d->wrap && !event->isAutoRepeat())) {
                decrementCurrentIndex();
                event->accept();
                return;
            } else if (d->wrap) {
                event->accept();
                return;
            }
        } else if ((d->orient == QQuickListView::Horizontal && !d->isRightToLeft() && event->key() == Qt::Key_Right)
                    || (d->orient == QQuickListView::Horizontal && d->isRightToLeft() && event->key() == Qt::Key_Left)
                    || (d->orient == QQuickListView::Vertical && event->key() == Qt::Key_Down)) {
            if (currentIndex() < d->model->count() - 1 || (d->wrap && !event->isAutoRepeat())) {
                incrementCurrentIndex();
                event->accept();
                return;
            } else if (d->wrap) {
                event->accept();
                return;
            }
        }
    }
    event->ignore();
    QQuickItemView::keyPressEvent(event);
}

void QQuickListView::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QQuickListView);
    if (d->isRightToLeft() && d->orient == QQuickListView::Horizontal) {
        // maintain position relative to the right edge
        int dx = newGeometry.width() - oldGeometry.width();
        setContentX(contentX() - dx);
    }
    QQuickItemView::geometryChanged(newGeometry, oldGeometry);
}


/*!
    \qmlmethod QtQuick2::ListView::incrementCurrentIndex()

    Increments the current index.  The current index will wrap
    if keyNavigationWraps is true and it is currently at the end.
    This method has no effect if the \l count is zero.

    \bold Note: methods should only be called after the Component has completed.
*/
void QQuickListView::incrementCurrentIndex()
{
    Q_D(QQuickListView);
    int count = d->model ? d->model->count() : 0;
    if (count && (currentIndex() < count - 1 || d->wrap)) {
        d->moveReason = QQuickListViewPrivate::SetIndex;
        int index = currentIndex()+1;
        setCurrentIndex((index >= 0 && index < count) ? index : 0);
    }
}

/*!
    \qmlmethod QtQuick2::ListView::decrementCurrentIndex()

    Decrements the current index.  The current index will wrap
    if keyNavigationWraps is true and it is currently at the beginning.
    This method has no effect if the \l count is zero.

    \bold Note: methods should only be called after the Component has completed.
*/
void QQuickListView::decrementCurrentIndex()
{
    Q_D(QQuickListView);
    int count = d->model ? d->model->count() : 0;
    if (count && (currentIndex() > 0 || d->wrap)) {
        d->moveReason = QQuickListViewPrivate::SetIndex;
        int index = currentIndex()-1;
        setCurrentIndex((index >= 0 && index < count) ? index : count-1);
    }
}

void QQuickListView::updateSections()
{
    Q_D(QQuickListView);
    if (isComponentComplete() && d->model) {
        QList<QByteArray> roles;
        if (d->sectionCriteria && !d->sectionCriteria->property().isEmpty())
            roles << d->sectionCriteria->property().toUtf8();
        d->model->setWatchedRoles(roles);
        d->updateSections();
        if (d->itemCount) {
            d->forceLayout = true;
            polish();
        }
    }
}

bool QQuickListViewPrivate::applyInsertionChange(const QDeclarativeChangeSet::Insert &change, ChangeResult *insertResult, QList<FxViewItem *> *addedItems)
{
    int modelIndex = change.index;
    int count = change.count;

    qreal tempPos = isRightToLeft() ? -position()-size() : position();
    int index = visibleItems.count() ? mapFromModel(modelIndex) : 0;

    if (index < 0) {
        int i = visibleItems.count() - 1;
        while (i > 0 && visibleItems.at(i)->index == -1)
            --i;
        if (i == 0 && visibleItems.first()->index == -1) {
            // there are no visible items except items marked for removal
            index = visibleItems.count();
        } else if (visibleItems.at(i)->index + 1 == modelIndex
            && visibleItems.at(i)->endPosition() <= buffer+tempPos+size()) {
            // Special case of appending an item to the model.
            index = visibleItems.count();
        } else {
            if (modelIndex < visibleIndex) {
                // Insert before visible items
                visibleIndex += count;
                for (int i = 0; i < visibleItems.count(); ++i) {
                    FxViewItem *item = visibleItems.at(i);
                    if (item->index != -1 && item->index >= modelIndex)
                        item->index += count;
                }
            }
            return true;
        }
    }

    // index can be the next item past the end of the visible items list (i.e. appended)
    int pos = 0;
    if (visibleItems.count()) {
        pos = index < visibleItems.count() ? visibleItems.at(index)->position()
                                                : visibleItems.last()->endPosition()+spacing;
    }

    int prevVisibleCount = visibleItems.count();
    if (insertResult->visiblePos.isValid() && pos < insertResult->visiblePos) {
        // Insert items before the visible item.
        int insertionIdx = index;
        int i = 0;
        int from = tempPos - buffer;

        for (i = count-1; i >= 0; --i) {
            if (pos > from && insertionIdx < visibleIndex) {
                // item won't be visible, just note the size for repositioning
                insertResult->sizeChangesBeforeVisiblePos += averageSize + spacing;
                pos -= averageSize + spacing;
            } else {
                // item is before first visible e.g. in cache buffer
                FxViewItem *item = 0;
                if (change.isMove() && (item = currentChanges.removedItems.take(change.moveKey(modelIndex + i))))
                    item->index = modelIndex + i;
                if (!item)
                    item = createItem(modelIndex + i);
                if (!item)
                    return false;

                visibleItems.insert(insertionIdx, item);
                if (insertionIdx == 0)
                    insertResult->changedFirstItem = true;
                if (!change.isMove())
                    addedItems->append(item);
                insertResult->sizeChangesBeforeVisiblePos += item->size() + spacing;
                pos -= item->size() + spacing;
            }
            index++;
        }
    } else {
        int i = 0;
        int to = buffer+tempPos+size();
        for (i = 0; i < count && pos <= to; ++i) {
            FxViewItem *item = 0;
            if (change.isMove() && (item = currentChanges.removedItems.take(change.moveKey(modelIndex + i))))
                item->index = modelIndex + i;
            if (!item)
                item = createItem(modelIndex + i);
            if (!item)
                return false;

            visibleItems.insert(index, item);
            if (index == 0)
                insertResult->changedFirstItem = true;
            if (!change.isMove())
                addedItems->append(item);
            insertResult->sizeChangesAfterVisiblePos += item->size() + spacing;
            pos += item->size() + spacing;
            ++index;
        }
    }

    for (; index < visibleItems.count(); ++index) {
        FxViewItem *item = visibleItems.at(index);
        if (item->index != -1)
            item->index += count;
    }

    updateVisibleIndex();

    return visibleItems.count() > prevVisibleCount;
}


/*!
    \qmlmethod QtQuick2::ListView::positionViewAtIndex(int index, PositionMode mode)

    Positions the view such that the \a index is at the position specified by
    \a mode:

    \list
    \o ListView.Beginning - position item at the top (or left for horizontal orientation) of the view.
    \o ListView.Center - position item in the center of the view.
    \o ListView.End - position item at bottom (or right for horizontal orientation) of the view.
    \o ListView.Visible - if any part of the item is visible then take no action, otherwise
    bring the item into view.
    \o ListView.Contain - ensure the entire item is visible.  If the item is larger than
    the view the item is positioned at the top (or left for horizontal orientation) of the view.
    \endlist

    If positioning the view at \a index would cause empty space to be displayed at
    the beginning or end of the view, the view will be positioned at the boundary.

    It is not recommended to use \l {Flickable::}{contentX} or \l {Flickable::}{contentY} to position the view
    at a particular index.  This is unreliable since removing items from the start
    of the list does not cause all other items to be repositioned, and because
    the actual start of the view can vary based on the size of the delegates.
    The correct way to bring an item into view is with \c positionViewAtIndex.

    \bold Note: methods should only be called after the Component has completed.  To position
    the view at startup, this method should be called by Component.onCompleted.  For
    example, to position the view at the end:

    \code
    Component.onCompleted: positionViewAtIndex(count - 1, ListView.Beginning)
    \endcode
*/

/*!
    \qmlmethod QtQuick2::ListView::positionViewAtBeginning()
    \qmlmethod QtQuick2::ListView::positionViewAtEnd()

    Positions the view at the beginning or end, taking into account any header or footer.

    It is not recommended to use \l {Flickable::}{contentX} or \l {Flickable::}{contentY} to position the view
    at a particular index.  This is unreliable since removing items from the start
    of the list does not cause all other items to be repositioned, and because
    the actual start of the view can vary based on the size of the delegates.

    \bold Note: methods should only be called after the Component has completed.  To position
    the view at startup, this method should be called by Component.onCompleted.  For
    example, to position the view at the end on startup:

    \code
    Component.onCompleted: positionViewAtEnd()
    \endcode
*/

/*!
    \qmlmethod int QtQuick2::ListView::indexAt(int x, int y)

    Returns the index of the visible item containing the point \a x, \a y in content
    coordinates.  If there is no item at the point specified, or the item is
    not visible -1 is returned.

    If the item is outside the visible area, -1 is returned, regardless of
    whether an item will exist at that point when scrolled into view.

    \bold Note: methods should only be called after the Component has completed.
*/

/*!
    \qmlmethod Item QtQuick2::ListView::itemAt(int x, int y)

    Returns the visible item containing the point \a x, \a y in content
    coordinates.  If there is no item at the point specified, or the item is
    not visible null is returned.

    If the item is outside the visible area, null is returned, regardless of
    whether an item will exist at that point when scrolled into view.

    \bold Note: methods should only be called after the Component has completed.
*/

QQuickListViewAttached *QQuickListView::qmlAttachedProperties(QObject *obj)
{
    return new QQuickListViewAttached(obj);
}

QT_END_NAMESPACE