qquickitemview.cpp

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**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
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****************************************************************************/

#include "qquickitemview_p_p.h"
#include <QtQuick/private/qquicktransition_p.h>

QT_BEGIN_NAMESPACE


FxViewItem::FxViewItem(QQuickItem *i, bool own, bool trackGeometry)
    : item(i)
    , transitionableItem(0)
    , ownItem(own)
    , releaseAfterTransition(false)
    , trackGeom(trackGeometry)
{
}

FxViewItem::~FxViewItem()
{
    delete transitionableItem;
    if (ownItem && item) {
        item->setParentItem(0);
        item->deleteLater();
        item = 0;
    }
}

qreal FxViewItem::itemX() const
{
    return transitionableItem ? transitionableItem->itemX() : item->x();
}

qreal FxViewItem::itemY() const
{
    return transitionableItem ? transitionableItem->itemY() : item->y();
}

void FxViewItem::moveTo(const QPointF &pos, bool immediate)
{
    if (transitionableItem)
        transitionableItem->moveTo(pos, immediate);
    else
        item->setPos(pos);
}

void FxViewItem::setVisible(bool visible)
{
    if (!visible && transitionableItem && transitionableItem->transitionScheduledOrRunning())
        return;
    item->setVisible(visible);
}

QQuickItemViewTransitioner::TransitionType FxViewItem::scheduledTransitionType() const
{
    return transitionableItem ? transitionableItem->nextTransitionType : QQuickItemViewTransitioner::NoTransition;
}

bool FxViewItem::transitionScheduledOrRunning() const
{
    return transitionableItem ? transitionableItem->transitionScheduledOrRunning() : false;
}

bool FxViewItem::transitionRunning() const
{
    return transitionableItem ? transitionableItem->transitionRunning() : false;
}

bool FxViewItem::isPendingRemoval() const
{
    return transitionableItem ? transitionableItem->isPendingRemoval() : false;
}

void FxViewItem::transitionNextReposition(QQuickItemViewTransitioner *transitioner, QQuickItemViewTransitioner::TransitionType type, bool asTarget)
{
    if (!transitioner)
        return;
    if (!transitionableItem)
        transitionableItem = new QQuickItemViewTransitionableItem(item);
    transitioner->transitionNextReposition(transitionableItem, type, asTarget);
}

bool FxViewItem::prepareTransition(QQuickItemViewTransitioner *transitioner, const QRectF &viewBounds)
{
    return transitionableItem ? transitionableItem->prepareTransition(transitioner, index, viewBounds) : false;
}

void FxViewItem::startTransition(QQuickItemViewTransitioner *transitioner)
{
    if (transitionableItem)
        transitionableItem->startTransition(transitioner, index);
}


QQuickItemViewChangeSet::QQuickItemViewChangeSet()
    : active(false)
{
    reset();
}

bool QQuickItemViewChangeSet::hasPendingChanges() const
{
    return !pendingChanges.isEmpty();
}

void QQuickItemViewChangeSet::applyChanges(const QQuickChangeSet &changeSet)
{
    pendingChanges.apply(changeSet);

    int moveId = -1;
    int moveOffset = 0;

    foreach (const QQuickChangeSet::Remove &r, changeSet.removes()) {
        itemCount -= r.count;
        if (moveId == -1 && newCurrentIndex >= r.index + r.count) {
            newCurrentIndex -= r.count;
            currentChanged = true;
        } else if (moveId == -1 && newCurrentIndex >= r.index && newCurrentIndex < r.index + r.count) {
            // current item has been removed.
            if (r.isMove()) {
                moveId = r.moveId;
                moveOffset = newCurrentIndex - r.index;
            } else {
                currentRemoved = true;
                newCurrentIndex = -1;
                if (itemCount)
                    newCurrentIndex = qMin(r.index, itemCount - 1);
            }
            currentChanged = true;
        }
    }
    foreach (const QQuickChangeSet::Insert &i, changeSet.inserts()) {
        if (moveId == -1) {
            if (itemCount && newCurrentIndex >= i.index) {
                newCurrentIndex += i.count;
                currentChanged = true;
            } else if (newCurrentIndex < 0) {
                newCurrentIndex = 0;
                currentChanged = true;
            } else if (newCurrentIndex == 0 && !itemCount) {
                // this is the first item, set the initial current index
                currentChanged = true;
            }
        } else if (moveId == i.moveId) {
            newCurrentIndex = i.index + moveOffset;
        }
        itemCount += i.count;
    }
}

void QQuickItemViewChangeSet::prepare(int currentIndex, int count)
{
    if (active)
        return;
    reset();
    active = true;
    itemCount = count;
    newCurrentIndex = currentIndex;
}

void QQuickItemViewChangeSet::reset()
{
    itemCount = 0;
    newCurrentIndex = -1;
    pendingChanges.clear();
    removedItems.clear();
    active = false;
    currentChanged = false;
    currentRemoved = false;
}

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

QQuickItemView::QQuickItemView(QQuickFlickablePrivate &dd, QQuickItem *parent)
    : QQuickFlickable(dd, parent)
{
    Q_D(QQuickItemView);
    d->init();
}

QQuickItemView::~QQuickItemView()
{
    Q_D(QQuickItemView);
    d->clear();
    if (d->ownModel)
        delete d->model;
    delete d->header;
    delete d->footer;
}


QQuickItem *QQuickItemView::currentItem() const
{
    Q_D(const QQuickItemView);
    if (!d->currentItem)
        return 0;
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->currentItem->item;
}

QVariant QQuickItemView::model() const
{
    Q_D(const QQuickItemView);
    return d->modelVariant;
}

void QQuickItemView::setModel(const QVariant &model)
{
    Q_D(QQuickItemView);
    if (d->modelVariant == model)
        return;
    if (d->model) {
        disconnect(d->model, SIGNAL(modelUpdated(QQuickChangeSet,bool)),
                this, SLOT(modelUpdated(QQuickChangeSet,bool)));
        disconnect(d->model, SIGNAL(initItem(int,QQuickItem*)), this, SLOT(initItem(int,QQuickItem*)));
        disconnect(d->model, SIGNAL(createdItem(int,QQuickItem*)), this, SLOT(createdItem(int,QQuickItem*)));
        disconnect(d->model, SIGNAL(destroyingItem(QQuickItem*)), this, SLOT(destroyingItem(QQuickItem*)));
    }

    QQuickVisualModel *oldModel = d->model;

    d->clear();
    d->model = 0;
    d->setPosition(d->contentStartOffset());
    d->modelVariant = model;

    QObject *object = qvariant_cast<QObject*>(model);
    QQuickVisualModel *vim = 0;
    if (object && (vim = qobject_cast<QQuickVisualModel *>(object))) {
        if (d->ownModel) {
            delete oldModel;
            d->ownModel = false;
        }
        d->model = vim;
    } else {
        if (!d->ownModel) {
            d->model = new QQuickVisualDataModel(qmlContext(this), this);
            d->ownModel = true;
            if (isComponentComplete())
                static_cast<QQuickVisualDataModel *>(d->model.data())->componentComplete();
        } else {
            d->model = oldModel;
        }
        if (QQuickVisualDataModel *dataModel = qobject_cast<QQuickVisualDataModel*>(d->model))
            dataModel->setModel(model);
    }

    if (d->model) {
        d->bufferMode = QQuickItemViewPrivate::BufferBefore | QQuickItemViewPrivate::BufferAfter;
        connect(d->model, SIGNAL(createdItem(int,QQuickItem*)), this, SLOT(createdItem(int,QQuickItem*)));
        connect(d->model, SIGNAL(initItem(int,QQuickItem*)), this, SLOT(initItem(int,QQuickItem*)));
        connect(d->model, SIGNAL(destroyingItem(QQuickItem*)), this, SLOT(destroyingItem(QQuickItem*)));
        if (isComponentComplete()) {
            updateSections();
            d->refill();
            if ((d->currentIndex >= d->model->count() || d->currentIndex < 0) && !d->currentIndexCleared) {
                setCurrentIndex(0);
            } else {
                d->moveReason = QQuickItemViewPrivate::SetIndex;
                d->updateCurrent(d->currentIndex);
                if (d->highlight && d->currentItem) {
                    if (d->autoHighlight)
                        d->resetHighlightPosition();
                    d->updateTrackedItem();
                }
                d->moveReason = QQuickItemViewPrivate::Other;
            }
            d->updateViewport();

            if (d->transitioner && d->transitioner->populateTransition) {
                d->forceLayout = true;
                d->transitioner->setPopulateTransitionEnabled(true);
                polish();
            }
        }
        connect(d->model, SIGNAL(modelUpdated(QQuickChangeSet,bool)),
                this, SLOT(modelUpdated(QQuickChangeSet,bool)));
        emit countChanged();
    }
    emit modelChanged();
}

QQmlComponent *QQuickItemView::delegate() const
{
    Q_D(const QQuickItemView);
    if (d->model) {
        if (QQuickVisualDataModel *dataModel = qobject_cast<QQuickVisualDataModel*>(d->model))
            return dataModel->delegate();
    }

    return 0;
}

void QQuickItemView::setDelegate(QQmlComponent *delegate)
{
    Q_D(QQuickItemView);
    if (delegate == this->delegate())
        return;
    if (!d->ownModel) {
        d->model = new QQuickVisualDataModel(qmlContext(this));
        d->ownModel = true;
    }
    if (QQuickVisualDataModel *dataModel = qobject_cast<QQuickVisualDataModel*>(d->model)) {
        int oldCount = dataModel->count();
        dataModel->setDelegate(delegate);
        if (isComponentComplete()) {
            for (int i = 0; i < d->visibleItems.count(); ++i)
                d->releaseItem(d->visibleItems.at(i));
            d->visibleItems.clear();
            d->releaseItem(d->currentItem);
            d->currentItem = 0;
            updateSections();
            d->refill();
            d->moveReason = QQuickItemViewPrivate::SetIndex;
            d->updateCurrent(d->currentIndex);
            if (d->highlight && d->currentItem) {
                if (d->autoHighlight)
                    d->resetHighlightPosition();
                d->updateTrackedItem();
            }
            d->moveReason = QQuickItemViewPrivate::Other;
            d->updateViewport();
        }
        if (oldCount != dataModel->count())
            emit countChanged();
    }
    emit delegateChanged();
}


int QQuickItemView::count() const
{
    Q_D(const QQuickItemView);
    if (!d->model)
        return 0;
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->model->count();
}

int QQuickItemView::currentIndex() const
{
    Q_D(const QQuickItemView);
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->currentIndex;
}

void QQuickItemView::setCurrentIndex(int index)
{
    Q_D(QQuickItemView);
    if (d->requestedIndex >= 0 && !d->requestedAsync)  // currently creating item
        return;
    d->currentIndexCleared = (index == -1);

    d->applyPendingChanges();
    if (index == d->currentIndex)
        return;
    if (isComponentComplete() && d->isValid()) {
        d->moveReason = QQuickItemViewPrivate::SetIndex;
        d->updateCurrent(index);
    } else if (d->currentIndex != index) {
        d->currentIndex = index;
        emit currentIndexChanged();
    }
}


bool QQuickItemView::isWrapEnabled() const
{
    Q_D(const QQuickItemView);
    return d->wrap;
}

void QQuickItemView::setWrapEnabled(bool wrap)
{
    Q_D(QQuickItemView);
    if (d->wrap == wrap)
        return;
    d->wrap = wrap;
    emit keyNavigationWrapsChanged();
}

int QQuickItemView::cacheBuffer() const
{
    Q_D(const QQuickItemView);
    return d->buffer;
}

void QQuickItemView::setCacheBuffer(int b)
{
    Q_D(QQuickItemView);
    if (d->buffer != b) {
        d->buffer = b;
        if (isComponentComplete()) {
            d->bufferMode = QQuickItemViewPrivate::BufferBefore | QQuickItemViewPrivate::BufferAfter;
            d->refill();
        }
        emit cacheBufferChanged();
    }
}


Qt::LayoutDirection QQuickItemView::layoutDirection() const
{
    Q_D(const QQuickItemView);
    return d->layoutDirection;
}

void QQuickItemView::setLayoutDirection(Qt::LayoutDirection layoutDirection)
{
    Q_D(QQuickItemView);
    if (d->layoutDirection != layoutDirection) {
        d->layoutDirection = layoutDirection;
        d->regenerate();
        emit layoutDirectionChanged();
        emit effectiveLayoutDirectionChanged();
    }
}

Qt::LayoutDirection QQuickItemView::effectiveLayoutDirection() const
{
    Q_D(const QQuickItemView);
    if (d->effectiveLayoutMirror)
        return d->layoutDirection == Qt::RightToLeft ? Qt::LeftToRight : Qt::RightToLeft;
    else
        return d->layoutDirection;
}


QQmlComponent *QQuickItemView::header() const
{
    Q_D(const QQuickItemView);
    return d->headerComponent;
}

QQuickItem *QQuickItemView::headerItem() const
{
    Q_D(const QQuickItemView);
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->header ? d->header->item : 0;
}

void QQuickItemView::setHeader(QQmlComponent *headerComponent)
{
    Q_D(QQuickItemView);
    if (d->headerComponent != headerComponent) {
        d->applyPendingChanges();
        delete d->header;
        d->header = 0;
        d->headerComponent = headerComponent;

        d->markExtentsDirty();

        if (isComponentComplete()) {
            d->updateHeader();
            d->updateFooter();
            d->updateViewport();
            d->fixupPosition();
        } else {
            emit headerItemChanged();
        }
        emit headerChanged();
    }
}

QQmlComponent *QQuickItemView::footer() const
{
    Q_D(const QQuickItemView);
    return d->footerComponent;
}

QQuickItem *QQuickItemView::footerItem() const
{
    Q_D(const QQuickItemView);
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->footer ? d->footer->item : 0;
}

void QQuickItemView::setFooter(QQmlComponent *footerComponent)
{
    Q_D(QQuickItemView);
    if (d->footerComponent != footerComponent) {
        d->applyPendingChanges();
        delete d->footer;
        d->footer = 0;
        d->footerComponent = footerComponent;

        if (isComponentComplete()) {
            d->updateFooter();
            d->updateViewport();
            d->fixupPosition();
        } else {
            emit footerItemChanged();
        }
        emit footerChanged();
    }
}

QQmlComponent *QQuickItemView::highlight() const
{
    Q_D(const QQuickItemView);
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->highlightComponent;
}

void QQuickItemView::setHighlight(QQmlComponent *highlightComponent)
{
    Q_D(QQuickItemView);
    if (highlightComponent != d->highlightComponent) {
        d->applyPendingChanges();
        d->highlightComponent = highlightComponent;
        d->createHighlight();
        if (d->currentItem)
            d->updateHighlight();
        emit highlightChanged();
    }
}

QQuickItem *QQuickItemView::highlightItem() const
{
    Q_D(const QQuickItemView);
    const_cast<QQuickItemViewPrivate*>(d)->applyPendingChanges();
    return d->highlight ? d->highlight->item : 0;
}

bool QQuickItemView::highlightFollowsCurrentItem() const
{
    Q_D(const QQuickItemView);
    return d->autoHighlight;
}

void QQuickItemView::setHighlightFollowsCurrentItem(bool autoHighlight)
{
    Q_D(QQuickItemView);
    if (d->autoHighlight != autoHighlight) {
        d->autoHighlight = autoHighlight;
        if (autoHighlight)
            d->updateHighlight();
        emit highlightFollowsCurrentItemChanged();
    }
}

QQuickItemView::HighlightRangeMode QQuickItemView::highlightRangeMode() const
{
    Q_D(const QQuickItemView);
    return static_cast<QQuickItemView::HighlightRangeMode>(d->highlightRange);
}

void QQuickItemView::setHighlightRangeMode(HighlightRangeMode mode)
{
    Q_D(QQuickItemView);
    if (d->highlightRange == mode)
        return;
    d->highlightRange = mode;
    d->haveHighlightRange = d->highlightRange != NoHighlightRange && d->highlightRangeStart <= d->highlightRangeEnd;
    emit highlightRangeModeChanged();
}

//###Possibly rename these properties, since they are very useful even without a highlight?
qreal QQuickItemView::preferredHighlightBegin() const
{
    Q_D(const QQuickItemView);
    return d->highlightRangeStart;
}

void QQuickItemView::setPreferredHighlightBegin(qreal start)
{
    Q_D(QQuickItemView);
    d->highlightRangeStartValid = true;
    if (d->highlightRangeStart == start)
        return;
    d->highlightRangeStart = start;
    d->haveHighlightRange = d->highlightRange != NoHighlightRange && d->highlightRangeStart <= d->highlightRangeEnd;
    emit preferredHighlightBeginChanged();
}

void QQuickItemView::resetPreferredHighlightBegin()
{
    Q_D(QQuickItemView);
    d->highlightRangeStartValid = false;
    if (d->highlightRangeStart == 0)
        return;
    d->highlightRangeStart = 0;
    emit preferredHighlightBeginChanged();
}

qreal QQuickItemView::preferredHighlightEnd() const
{
    Q_D(const QQuickItemView);
    return d->highlightRangeEnd;
}

void QQuickItemView::setPreferredHighlightEnd(qreal end)
{
    Q_D(QQuickItemView);
    d->highlightRangeEndValid = true;
    if (d->highlightRangeEnd == end)
        return;
    d->highlightRangeEnd = end;
    d->haveHighlightRange = d->highlightRange != NoHighlightRange && d->highlightRangeStart <= d->highlightRangeEnd;
    emit preferredHighlightEndChanged();
}

void QQuickItemView::resetPreferredHighlightEnd()
{
    Q_D(QQuickItemView);
    d->highlightRangeEndValid = false;
    if (d->highlightRangeEnd == 0)
        return;
    d->highlightRangeEnd = 0;
    emit preferredHighlightEndChanged();
}

int QQuickItemView::highlightMoveDuration() const
{
    Q_D(const QQuickItemView);
    return d->highlightMoveDuration;
}

void QQuickItemView::setHighlightMoveDuration(int duration)
{
    Q_D(QQuickItemView);
    if (d->highlightMoveDuration != duration) {
        d->highlightMoveDuration = duration;
        emit highlightMoveDurationChanged();
    }
}

QQuickTransition *QQuickItemView::populateTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->populateTransition : 0;
}

void QQuickItemView::setPopulateTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->populateTransition != transition) {
        d->transitioner->populateTransition = transition;
        emit populateTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::addTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->addTransition : 0;
}

void QQuickItemView::setAddTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->addTransition != transition) {
        d->transitioner->addTransition = transition;
        emit addTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::addDisplacedTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->addDisplacedTransition : 0;
}

void QQuickItemView::setAddDisplacedTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->addDisplacedTransition != transition) {
        d->transitioner->addDisplacedTransition = transition;
        emit addDisplacedTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::moveTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->moveTransition : 0;
}

void QQuickItemView::setMoveTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->moveTransition != transition) {
        d->transitioner->moveTransition = transition;
        emit moveTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::moveDisplacedTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->moveDisplacedTransition : 0;
}

void QQuickItemView::setMoveDisplacedTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->moveDisplacedTransition != transition) {
        d->transitioner->moveDisplacedTransition = transition;
        emit moveDisplacedTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::removeTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->removeTransition : 0;
}

void QQuickItemView::setRemoveTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->removeTransition != transition) {
        d->transitioner->removeTransition = transition;
        emit removeTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::removeDisplacedTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->removeDisplacedTransition : 0;
}

void QQuickItemView::setRemoveDisplacedTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->removeDisplacedTransition != transition) {
        d->transitioner->removeDisplacedTransition = transition;
        emit removeDisplacedTransitionChanged();
    }
}

QQuickTransition *QQuickItemView::displacedTransition() const
{
    Q_D(const QQuickItemView);
    return d->transitioner ? d->transitioner->displacedTransition : 0;
}

void QQuickItemView::setDisplacedTransition(QQuickTransition *transition)
{
    Q_D(QQuickItemView);
    d->createTransitioner();
    if (d->transitioner->displacedTransition != transition) {
        d->transitioner->displacedTransition = transition;
        emit displacedTransitionChanged();
    }
}

void QQuickItemViewPrivate::positionViewAtIndex(int index, int mode)
{
    Q_Q(QQuickItemView);
    if (!isValid())
        return;
    if (mode < QQuickItemView::Beginning || mode > QQuickItemView::Contain)
        return;

    applyPendingChanges();
    int idx = qMax(qMin(index, model->count()-1), 0);

    qreal pos = isContentFlowReversed() ? -position() - size() : position();
    FxViewItem *item = visibleItem(idx);
    qreal maxExtent;
    if (layoutOrientation() == Qt::Vertical)
        maxExtent = -q->maxYExtent();
    else
        maxExtent = isContentFlowReversed() ? q->minXExtent()-size(): -q->maxXExtent();
    if (!item) {
        int itemPos = positionAt(idx);
        changedVisibleIndex(idx);
        // save the currently visible items in case any of them end up visible again
        QList<FxViewItem *> oldVisible = visibleItems;
        visibleItems.clear();
        setPosition(qMin(qreal(itemPos), maxExtent));
        // now release the reference to all the old visible items.
        for (int i = 0; i < oldVisible.count(); ++i)
            releaseItem(oldVisible.at(i));
        item = visibleItem(idx);
    }
    if (item) {
        const qreal itemPos = item->position();
        switch (mode) {
        case QQuickItemView::Beginning:
            pos = itemPos;
            if (index < 0 && header)
                pos -= headerSize();
            break;
        case QQuickItemView::Center:
            pos = itemPos - (size() - item->size())/2;
            break;
        case QQuickItemView::End:
            pos = itemPos - size() + item->size();
            if (index >= model->count() && footer)
                pos += footerSize();
            break;
        case QQuickItemView::Visible:
            if (itemPos > pos + size())
                pos = itemPos - size() + item->size();
            else if (item->endPosition() <= pos)
                pos = itemPos;
            break;
        case QQuickItemView::Contain:
            if (item->endPosition() >= pos + size())
                pos = itemPos - size() + item->size();
            if (itemPos < pos)
                pos = itemPos;
        }
        pos = qMin(pos, maxExtent);
        qreal minExtent;
        if (layoutOrientation() == Qt::Vertical)
            minExtent = -q->minYExtent();
        else
            minExtent = isContentFlowReversed() ? q->maxXExtent()-size(): -q->minXExtent();
        pos = qMax(pos, minExtent);
        moveReason = QQuickItemViewPrivate::Other;
        q->cancelFlick();
        setPosition(pos);

        if (highlight) {
            if (autoHighlight)
                resetHighlightPosition();
            updateHighlight();
        }
    }
    fixupPosition();
}

void QQuickItemView::positionViewAtIndex(int index, int mode)
{
    Q_D(QQuickItemView);
    if (!d->isValid() || index < 0 || index >= d->model->count())
        return;
    d->positionViewAtIndex(index, mode);
}


void QQuickItemView::positionViewAtBeginning()
{
    Q_D(QQuickItemView);
    if (!d->isValid())
        return;
    d->positionViewAtIndex(-1, Beginning);
}

void QQuickItemView::positionViewAtEnd()
{
    Q_D(QQuickItemView);
    if (!d->isValid())
        return;
    d->positionViewAtIndex(d->model->count(), End);
}

int QQuickItemView::indexAt(qreal x, qreal y) const
{
    Q_D(const QQuickItemView);
    for (int i = 0; i < d->visibleItems.count(); ++i) {
        const FxViewItem *item = d->visibleItems.at(i);
        if (item->contains(x, y))
            return item->index;
    }

    return -1;
}

QQuickItem *QQuickItemView::itemAt(qreal x, qreal y) const
{
    Q_D(const QQuickItemView);
    for (int i = 0; i < d->visibleItems.count(); ++i) {
        const FxViewItem *item = d->visibleItems.at(i);
        if (item->contains(x, y))
            return item->item;
    }

    return 0;
}

void QQuickItemViewPrivate::applyPendingChanges()
{
    Q_Q(QQuickItemView);
    if (q->isComponentComplete() && currentChanges.hasPendingChanges())
        layout();
}

int QQuickItemViewPrivate::findMoveKeyIndex(QQuickChangeSet::MoveKey key, const QVector<QQuickChangeSet::Remove> &changes) const
{
    for (int i=0; i<changes.count(); i++) {
        for (int j=changes[i].index; j<changes[i].index + changes[i].count; j++) {
            if (changes[i].moveKey(j) == key)
                return j;
        }
    }
    return -1;
}

// for debugging only
void QQuickItemViewPrivate::checkVisible() const
{
    int skip = 0;
    for (int i = 0; i < visibleItems.count(); ++i) {
        FxViewItem *item = visibleItems.at(i);
        if (item->index == -1) {
            ++skip;
        } else if (item->index != visibleIndex + i - skip) {
            qFatal("index %d %d %d", visibleIndex, i, item->index);
        }
    }
}

// for debugging only
void QQuickItemViewPrivate::showVisibleItems() const
{
    qDebug() << "Visible items:";
    for (int i = 0; i < visibleItems.count(); ++i) {
        qDebug() << "\t" << visibleItems[i]->index
                 << visibleItems[i]->item->objectName()
                 << visibleItems[i]->position();
    }
}

void QQuickItemViewPrivate::itemGeometryChanged(QQuickItem *item, const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_Q(QQuickItemView);
    QQuickFlickablePrivate::itemGeometryChanged(item, newGeometry, oldGeometry);
    if (!q->isComponentComplete())
        return;

    if (header && header->item == item) {
        updateHeader();
        markExtentsDirty();
        if (!q->isMoving() && !q->isFlicking())
            fixupPosition();
    } else if (footer && footer->item == item) {
        updateFooter();
        markExtentsDirty();
        if (!q->isMoving() && !q->isFlicking())
            fixupPosition();
    }

    if (currentItem && currentItem->item == item) {
        // don't allow item movement transitions to trigger a re-layout and
        // start new transitions
        bool prevDisableLayout = disableLayout;
        if (!disableLayout) {
            FxViewItem *actualItem = transitioner ? visibleItem(currentIndex) : 0;
            if (actualItem && actualItem->transitionRunning())
                disableLayout = true;
        }
        updateHighlight();
        disableLayout = prevDisableLayout;
    }

    if (trackedItem && trackedItem->item == item)
        q->trackedPositionChanged();
}

void QQuickItemView::destroyRemoved()
{
    Q_D(QQuickItemView);
    for (QList<FxViewItem*>::Iterator it = d->visibleItems.begin();
            it != d->visibleItems.end();) {
        FxViewItem *item = *it;
        if (item->index == -1 && item->attached->delayRemove() == false) {
            if (d->transitioner && d->transitioner->canTransition(QQuickItemViewTransitioner::RemoveTransition, true)) {
                // don't remove from visibleItems until next layout()
                d->runDelayedRemoveTransition = true;
                QObject::disconnect(item->attached, SIGNAL(delayRemoveChanged()), this, SLOT(destroyRemoved()));
                ++it;
            } else {
                d->releaseItem(item);
                it = d->visibleItems.erase(it);
            }
        } else {
            ++it;
        }
    }

    // Correct the positioning of the items
    d->updateSections();
    d->forceLayout = true;
    polish();
}

void QQuickItemView::modelUpdated(const QQuickChangeSet &changeSet, bool reset)
{
    Q_D(QQuickItemView);
    if (reset) {
        if (d->transitioner)
            d->transitioner->setPopulateTransitionEnabled(true);
        d->moveReason = QQuickItemViewPrivate::SetIndex;
        d->regenerate();
        if (d->highlight && d->currentItem) {
            if (d->autoHighlight)
                d->resetHighlightPosition();
            d->updateTrackedItem();
        }
        d->moveReason = QQuickItemViewPrivate::Other;
        emit countChanged();
        if (d->transitioner && d->transitioner->populateTransition) {
            d->forceLayout = true;
            polish();
        }
    } else {
        d->currentChanges.prepare(d->currentIndex, d->itemCount);
        d->currentChanges.applyChanges(changeSet);
        polish();
    }
}

void QQuickItemView::animStopped()
{
    Q_D(QQuickItemView);
    d->bufferMode = QQuickItemViewPrivate::BufferBefore | QQuickItemViewPrivate::BufferAfter;
    d->refill();
    if (d->haveHighlightRange && d->highlightRange == QQuickItemView::StrictlyEnforceRange)
        d->updateHighlight();
}


void QQuickItemView::trackedPositionChanged()
{
    Q_D(QQuickItemView);
    if (!d->trackedItem || !d->currentItem)
        return;
    if (d->moveReason == QQuickItemViewPrivate::SetIndex) {
        qreal trackedPos = d->trackedItem->position();
        qreal trackedSize = d->trackedItem->size();
        qreal viewPos = d->isContentFlowReversed() ? -d->position()-d->size() : d->position();
        qreal pos = viewPos;
        if (d->haveHighlightRange) {
            if (trackedPos > pos + d->highlightRangeEnd - trackedSize)
                pos = trackedPos - d->highlightRangeEnd + trackedSize;
            if (trackedPos < pos + d->highlightRangeStart)
                pos = trackedPos - d->highlightRangeStart;
            if (d->highlightRange != StrictlyEnforceRange) {
                if (pos > d->endPosition() - d->size())
                    pos = d->endPosition() - d->size();
                if (pos < d->startPosition())
                    pos = d->startPosition();
            }
        } else {
            if (d->trackedItem != d->currentItem) {
                // also make section header visible
                trackedPos -= d->currentItem->sectionSize();
                trackedSize += d->currentItem->sectionSize();
            }
            qreal trackedEndPos = d->trackedItem->endPosition();
            qreal toItemPos = d->currentItem->position();
            qreal toItemEndPos = d->currentItem->endPosition();
            if (d->showHeaderForIndex(d->currentIndex)) {
                qreal startOffset = -d->contentStartOffset();
                trackedPos -= startOffset;
                trackedEndPos -= startOffset;
                toItemPos -= startOffset;
                toItemEndPos -= startOffset;
            } else if (d->showFooterForIndex(d->currentIndex)) {
                qreal endOffset = d->footerSize();
                if (d->layoutOrientation() == Qt::Vertical)
                    endOffset += d->vData.endMargin;
                else if (d->isContentFlowReversed())
                    endOffset += d->hData.startMargin;
                else
                    endOffset += d->hData.endMargin;
                trackedPos += endOffset;
                trackedEndPos += endOffset;
                toItemPos += endOffset;
                toItemEndPos += endOffset;
            }

            if (trackedEndPos >= viewPos + d->size()
                && toItemEndPos >= viewPos + d->size()) {
                if (trackedEndPos <= toItemEndPos) {
                    pos = trackedEndPos - d->size();
                    if (trackedSize > d->size())
                        pos = trackedPos;
                } else {
                    pos = toItemEndPos - d->size();
                    if (d->currentItem->size() > d->size())
                        pos = d->currentItem->position();
                }
            }
            if (trackedPos < pos && toItemPos < pos)
                pos = qMax(trackedPos, toItemPos);
        }
        if (viewPos != pos) {
            cancelFlick();
            d->calcVelocity = true;
            d->setPosition(pos);
            d->calcVelocity = false;
        }
    }
}

void QQuickItemView::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QQuickItemView);
    d->markExtentsDirty();
    if (isComponentComplete() && d->isValid()) {
        d->forceLayout = true;
        polish();
    }
    QQuickFlickable::geometryChanged(newGeometry, oldGeometry);
}


qreal QQuickItemView::minYExtent() const
{
    Q_D(const QQuickItemView);
    if (d->layoutOrientation() == Qt::Horizontal)
        return QQuickFlickable::minYExtent();

    if (d->vData.minExtentDirty) {
        d->minExtent = d->vData.startMargin-d->startPosition();
        if (d->header)
            d->minExtent += d->headerSize();
        if (d->haveHighlightRange && d->highlightRange == StrictlyEnforceRange) {
            d->minExtent += d->highlightRangeStart;
            if (d->visibleItem(0))
                d->minExtent -= d->visibleItem(0)->sectionSize();
            d->minExtent = qMax(d->minExtent, -(d->endPositionAt(0) - d->highlightRangeEnd));
        }
        d->vData.minExtentDirty = false;
    }

    return d->minExtent;
}

qreal QQuickItemView::maxYExtent() const
{
    Q_D(const QQuickItemView);
    if (d->layoutOrientation() == Qt::Horizontal)
        return height();

    if (d->vData.maxExtentDirty) {
        if (!d->model || !d->model->count()) {
            d->maxExtent = d->header ? -d->headerSize() : 0;
            d->maxExtent += height();
        } else if (d->haveHighlightRange && d->highlightRange == StrictlyEnforceRange) {
            d->maxExtent = -(d->positionAt(d->model->count()-1) - d->highlightRangeStart);
            if (d->highlightRangeEnd != d->highlightRangeStart)
                d->maxExtent = qMin(d->maxExtent, -(d->endPosition() - d->highlightRangeEnd));
        } else {
            d->maxExtent = -(d->endPosition() - height());
        }

        if (d->footer)
            d->maxExtent -= d->footerSize();
        d->maxExtent -= d->vData.endMargin;
        qreal minY = minYExtent();
        if (d->maxExtent > minY)
            d->maxExtent = minY;
        d->vData.maxExtentDirty = false;
    }
    return d->maxExtent;
}

qreal QQuickItemView::minXExtent() const
{
    Q_D(const QQuickItemView);
    if (d->layoutOrientation() == Qt::Vertical)
        return QQuickFlickable::minXExtent();

    if (d->hData.minExtentDirty) {
        d->minExtent = -d->startPosition() + d->hData.startMargin;
        qreal highlightStart;
        qreal highlightEnd;
        qreal endPositionFirstItem = 0;
        if (d->isContentFlowReversed()) {
            if (d->model && d->model->count())
                endPositionFirstItem = d->positionAt(d->model->count()-1);
            else if (d->header)
                d->minExtent += d->headerSize();
            highlightStart = d->highlightRangeEndValid ? d->size() - d->highlightRangeEnd : d->size();
            highlightEnd = d->highlightRangeStartValid ? d->size() - d->highlightRangeStart : d->size();
            if (d->footer)
                d->minExtent += d->footerSize();
            qreal maxX = maxXExtent();
            if (d->minExtent < maxX)
                d->minExtent = maxX;
        } else {
            endPositionFirstItem = d->endPositionAt(0);
            highlightStart = d->highlightRangeStart;
            highlightEnd = d->highlightRangeEnd;
            if (d->header)
                d->minExtent += d->headerSize();
        }
        if (d->haveHighlightRange && d->highlightRange == StrictlyEnforceRange) {
            d->minExtent += highlightStart;
            d->minExtent = d->isContentFlowReversed()
                                ? qMin(d->minExtent, endPositionFirstItem + highlightEnd)
                                : qMax(d->minExtent, -(endPositionFirstItem - highlightEnd));
        }
        d->hData.minExtentDirty = false;
    }

    return d->minExtent;
}

qreal QQuickItemView::maxXExtent() const
{
    Q_D(const QQuickItemView);
    if (d->layoutOrientation() == Qt::Vertical)
        return width();

    if (d->hData.maxExtentDirty) {
        qreal highlightStart;
        qreal highlightEnd;
        qreal lastItemPosition = 0;
        d->maxExtent = 0;
        if (d->isContentFlowReversed()) {
            highlightStart = d->highlightRangeEndValid ? d->size() - d->highlightRangeEnd : d->size();
            highlightEnd = d->highlightRangeStartValid ? d->size() - d->highlightRangeStart : d->size();
            lastItemPosition = d->endPosition();
        } else {
            highlightStart = d->highlightRangeStart;
            highlightEnd = d->highlightRangeEnd;
            if (d->model && d->model->count())
                lastItemPosition = d->positionAt(d->model->count()-1);
        }
        if (!d->model || !d->model->count()) {
            if (!d->isContentFlowReversed())
                d->maxExtent = d->header ? -d->headerSize() : 0;
            d->maxExtent += width();
        } else if (d->haveHighlightRange && d->highlightRange == StrictlyEnforceRange) {
            d->maxExtent = -(lastItemPosition - highlightStart);
            if (highlightEnd != highlightStart) {
                d->maxExtent = d->isContentFlowReversed()
                        ? qMax(d->maxExtent, -(d->endPosition() - highlightEnd))
                        : qMin(d->maxExtent, -(d->endPosition() - highlightEnd));
            }
        } else {
            d->maxExtent = -(d->endPosition() - width());
        }
        if (d->isContentFlowReversed()) {
            if (d->header)
                d->maxExtent -= d->headerSize();
            d->maxExtent -= d->hData.endMargin;
        } else {
            if (d->footer)
                d->maxExtent -= d->footerSize();
            d->maxExtent -= d->hData.endMargin;
            qreal minX = minXExtent();
            if (d->maxExtent > minX)
                d->maxExtent = minX;
        }
        d->hData.maxExtentDirty = false;
    }

    return d->maxExtent;
}

void QQuickItemView::setContentX(qreal pos)
{
    Q_D(QQuickItemView);
    // Positioning the view manually should override any current movement state
    d->moveReason = QQuickItemViewPrivate::Other;
    QQuickFlickable::setContentX(pos);
}

void QQuickItemView::setContentY(qreal pos)
{
    Q_D(QQuickItemView);
    // Positioning the view manually should override any current movement state
    d->moveReason = QQuickItemViewPrivate::Other;
    QQuickFlickable::setContentY(pos);
}

qreal QQuickItemView::xOrigin() const
{
    Q_D(const QQuickItemView);
    if (d->isContentFlowReversed())
        return -maxXExtent() + d->size() - d->hData.endMargin;
    else
        return -minXExtent() + d->hData.startMargin;
}

void QQuickItemView::updatePolish()
{
    Q_D(QQuickItemView);
    QQuickFlickable::updatePolish();
    d->layout();
}

void QQuickItemView::componentComplete()
{
    Q_D(QQuickItemView);
    if (d->model && d->ownModel)
        static_cast<QQuickVisualDataModel *>(d->model.data())->componentComplete();

    QQuickFlickable::componentComplete();

    updateSections();
    d->updateHeader();
    d->updateFooter();
    d->updateViewport();
    d->setPosition(d->contentStartOffset());
    if (d->transitioner)
        d->transitioner->setPopulateTransitionEnabled(true);

    if (d->isValid()) {
        d->refill();
        d->moveReason = QQuickItemViewPrivate::SetIndex;
        if (d->currentIndex < 0 && !d->currentIndexCleared)
            d->updateCurrent(0);
        else
            d->updateCurrent(d->currentIndex);
        if (d->highlight && d->currentItem) {
            if (d->autoHighlight)
                d->resetHighlightPosition();
            d->updateTrackedItem();
        }
        d->moveReason = QQuickItemViewPrivate::Other;
        d->fixupPosition();
    }
    if (d->model && d->model->count())
        emit countChanged();
}



QQuickItemViewPrivate::QQuickItemViewPrivate()
    : itemCount(0)
    , buffer(0), bufferMode(BufferBefore | BufferAfter)
    , layoutDirection(Qt::LeftToRight)
    , moveReason(Other)
    , visibleIndex(0)
    , currentIndex(-1), currentItem(0)
    , trackedItem(0), requestedIndex(-1), requestedItem(0)
    , highlightComponent(0), highlight(0)
    , highlightRange(QQuickItemView::NoHighlightRange)
    , highlightRangeStart(0), highlightRangeEnd(0)
    , highlightMoveDuration(150)
    , headerComponent(0), header(0), footerComponent(0), footer(0)
    , transitioner(0)
    , minExtent(0), maxExtent(0)
    , ownModel(false), wrap(false)
    , disableLayout(false), inViewportMoved(false), forceLayout(false), currentIndexCleared(false)
    , haveHighlightRange(false), autoHighlight(true), highlightRangeStartValid(false), highlightRangeEndValid(false)
    , fillCacheBuffer(false), inRequest(false), requestedAsync(false)
    , runDelayedRemoveTransition(false)
{
}

QQuickItemViewPrivate::~QQuickItemViewPrivate()
{
    if (transitioner)
        transitioner->setChangeListener(0);
    delete transitioner;
}

bool QQuickItemViewPrivate::isValid() const
{
    return model && model->count() && model->isValid();
}

qreal QQuickItemViewPrivate::position() const
{
    Q_Q(const QQuickItemView);
    return layoutOrientation() == Qt::Vertical ? q->contentY() : q->contentX();
}

qreal QQuickItemViewPrivate::size() const
{
    Q_Q(const QQuickItemView);
    return layoutOrientation() == Qt::Vertical ? q->height() : q->width();
}

qreal QQuickItemViewPrivate::startPosition() const
{
    return isContentFlowReversed() ? -lastPosition() : originPosition();
}

qreal QQuickItemViewPrivate::endPosition() const
{
    return isContentFlowReversed() ? -originPosition() : lastPosition();
}

qreal QQuickItemViewPrivate::contentStartOffset() const
{
    qreal pos = -headerSize();
    if (layoutOrientation() == Qt::Vertical)
        pos -= vData.startMargin;
    else if (isContentFlowReversed())
        pos -= hData.endMargin;
    else
        pos -= hData.startMargin;

    return pos;
}

int QQuickItemViewPrivate::findLastVisibleIndex(int defaultValue) const
{
    if (visibleItems.count()) {
        int i = visibleItems.count() - 1;
        while (i > 0 && visibleItems.at(i)->index == -1)
            --i;
        if (visibleItems.at(i)->index != -1)
            return visibleItems.at(i)->index;
    }
    return defaultValue;
}

FxViewItem *QQuickItemViewPrivate::visibleItem(int modelIndex) const {
    if (modelIndex >= visibleIndex && modelIndex < visibleIndex + visibleItems.count()) {
        for (int i = modelIndex - visibleIndex; i < visibleItems.count(); ++i) {
            FxViewItem *item = visibleItems.at(i);
            if (item->index == modelIndex)
                return item;
        }
    }
    return 0;
}

// should rename to firstItemInView() to avoid confusion with other "*visible*" methods
// that don't look at the view position and size
FxViewItem *QQuickItemViewPrivate::firstVisibleItem() const {
    const qreal pos = isContentFlowReversed() ? -position()-size() : position();
    for (int i = 0; i < visibleItems.count(); ++i) {
        FxViewItem *item = visibleItems.at(i);
        if (item->index != -1 && item->endPosition() > pos)
            return item;
    }
    return visibleItems.count() ? visibleItems.first() : 0;
}

int QQuickItemViewPrivate::findLastIndexInView() const
{
    const qreal viewEndPos = isContentFlowReversed() ? -position() : position() + size();
    for (int i=visibleItems.count() - 1; i>=0; i--) {
        if (visibleItems.at(i)->position() <= viewEndPos && visibleItems.at(i)->index != -1)
            return visibleItems.at(i)->index;
    }
    return -1;
}

// Map a model index to visibleItems list index.
// These may differ if removed items are still present in the visible list,
// e.g. doing a removal animation
int QQuickItemViewPrivate::mapFromModel(int modelIndex) const
{
    if (modelIndex < visibleIndex || modelIndex >= visibleIndex + visibleItems.count())
        return -1;
    for (int i = 0; i < visibleItems.count(); ++i) {
        FxViewItem *item = visibleItems.at(i);
        if (item->index == modelIndex)
            return i;
        if (item->index > modelIndex)
            return -1;
    }
    return -1; // Not in visibleList
}

void QQuickItemViewPrivate::init()
{
    Q_Q(QQuickItemView);
    QQuickItemPrivate::get(contentItem)->childrenDoNotOverlap = true;
    q->setFlag(QQuickItem::ItemIsFocusScope);
    QObject::connect(q, SIGNAL(movementEnded()), q, SLOT(animStopped()));
    q->setFlickableDirection(QQuickFlickable::VerticalFlick);
}

void QQuickItemViewPrivate::updateCurrent(int modelIndex)
{
    Q_Q(QQuickItemView);
    applyPendingChanges();
    if (!q->isComponentComplete() || !isValid() || modelIndex < 0 || modelIndex >= model->count()) {
        if (currentItem) {
            currentItem->attached->setIsCurrentItem(false);
            releaseItem(currentItem);
            currentItem = 0;
            currentIndex = modelIndex;
            emit q->currentIndexChanged();
            emit q->currentItemChanged();
            updateHighlight();
        } else if (currentIndex != modelIndex) {
            currentIndex = modelIndex;
            emit q->currentIndexChanged();
        }
        return;
    }

    if (currentItem && currentIndex == modelIndex) {
        updateHighlight();
        return;
    }

    FxViewItem *oldCurrentItem = currentItem;
    int oldCurrentIndex = currentIndex;
    currentIndex = modelIndex;
    currentItem = createItem(modelIndex, false);
    if (oldCurrentItem && (!currentItem || oldCurrentItem->item != currentItem->item))
        oldCurrentItem->attached->setIsCurrentItem(false);
    if (currentItem) {
        currentItem->item->setFocus(true);
        currentItem->attached->setIsCurrentItem(true);
        initializeCurrentItem();
    }

    updateHighlight();
    if (oldCurrentIndex != currentIndex)
        emit q->currentIndexChanged();
    if (oldCurrentItem != currentItem)
        emit q->currentItemChanged();
    releaseItem(oldCurrentItem);
}

void QQuickItemViewPrivate::clear()
{
    currentChanges.reset();
    timeline.clear();

    for (int i = 0; i < visibleItems.count(); ++i)
        releaseItem(visibleItems.at(i));
    visibleItems.clear();
    visibleIndex = 0;

    for (int i = 0; i < releasePendingTransition.count(); ++i) {
        releasePendingTransition.at(i)->releaseAfterTransition = false;
        releaseItem(releasePendingTransition.at(i));
    }
    releasePendingTransition.clear();

    releaseItem(currentItem);
    currentItem = 0;
    createHighlight();
    trackedItem = 0;

    if (requestedIndex >= 0 && requestedAsync) {
        if (model)
            model->cancel(requestedIndex);
        requestedIndex = -1;
    }

    markExtentsDirty();
    itemCount = 0;
}


void QQuickItemViewPrivate::mirrorChange()
{
    Q_Q(QQuickItemView);
    regenerate();
    emit q->effectiveLayoutDirectionChanged();
}

void QQuickItemViewPrivate::refill()
{
    qreal s = qMax(size(), qreal(0.));
    if (isContentFlowReversed())
        refill(-position()-s, -position());
    else
        refill(position(), position()+s);
}

void QQuickItemViewPrivate::refill(qreal from, qreal to)
{
    Q_Q(QQuickItemView);
    if (!isValid() || !q->isComponentComplete())
        return;

    currentChanges.reset();

    int prevCount = itemCount;
    itemCount = model->count();
    qreal bufferFrom = from - buffer;
    qreal bufferTo = to + buffer;
    qreal fillFrom = from;
    qreal fillTo = to;

    bool added = addVisibleItems(fillFrom, fillTo, false);
    bool removed = removeNonVisibleItems(bufferFrom, bufferTo);

    if (buffer && bufferMode != NoBuffer) {
        if (bufferMode & BufferAfter)
            fillTo = bufferTo;
        if (bufferMode & BufferBefore)
            fillFrom = bufferFrom;
        added |= addVisibleItems(fillFrom, fillTo, true);
    }

    if (added || removed) {
        markExtentsDirty();
        updateBeginningEnd();
        visibleItemsChanged();
        updateHeader();
        updateFooter();
        updateViewport();
    }

    if (prevCount != itemCount)
        emit q->countChanged();
}

void QQuickItemViewPrivate::regenerate()
{
    Q_Q(QQuickItemView);
    if (q->isComponentComplete()) {
        currentChanges.reset();
        delete header;
        header = 0;
        delete footer;
        footer = 0;
        updateHeader();
        updateFooter();
        clear();
        updateViewport();
        setPosition(contentStartOffset());
        refill();
        updateCurrent(currentIndex);
    }
}

void QQuickItemViewPrivate::updateViewport()
{
    Q_Q(QQuickItemView);
    if (isValid()) {
        qreal extra = headerSize() + footerSize();
        if (layoutOrientation() == Qt::Vertical)
            q->setContentHeight(endPosition() - startPosition() + extra);
        else
            q->setContentWidth(endPosition() - startPosition() + extra);
    }
}

void QQuickItemViewPrivate::layout()
{
    Q_Q(QQuickItemView);
    if (disableLayout)
        return;

    if (!isValid() && !visibleItems.count()) {
        clear();
        setPosition(contentStartOffset());
        if (transitioner)
            transitioner->setPopulateTransitionEnabled(false);
        return;
    }

    if (runDelayedRemoveTransition && transitioner
            && transitioner->canTransition(QQuickItemViewTransitioner::RemoveTransition, false)) {
        // assume that any items moving now are moving due to the remove - if they schedule
        // a different transition, that will override this one anyway
        for (int i=0; i<visibleItems.count(); i++)
            visibleItems[i]->transitionNextReposition(transitioner, QQuickItemViewTransitioner::RemoveTransition, false);
    }

    ChangeResult insertionPosChanges;
    ChangeResult removalPosChanges;
    if (!applyModelChanges(&insertionPosChanges, &removalPosChanges) && !forceLayout) {
        if (fillCacheBuffer) {
            fillCacheBuffer = false;
            refill();
        }
        return;
    }
    forceLayout = false;

    if (transitioner && transitioner->canTransition(QQuickItemViewTransitioner::PopulateTransition, true)) {
        for (int i=0; i<visibleItems.count(); i++)
            visibleItems.at(i)->transitionNextReposition(transitioner, QQuickItemViewTransitioner::PopulateTransition, true);
    }
    layoutVisibleItems();

    int lastIndexInView = findLastIndexInView();
    refill();
    markExtentsDirty();
    updateHighlight();

    if (!q->isMoving() && !q->isFlicking()) {
        fixupPosition();
        refill();
    }

    updateHeader();
    updateFooter();
    updateViewport();
    updateUnrequestedPositions();

    if (transitioner) {
        // items added in the last refill() may need to be transitioned in - e.g. a remove
        // causes items to slide up into view
        if (transitioner->canTransition(QQuickItemViewTransitioner::MoveTransition, false)
                || transitioner->canTransition(QQuickItemViewTransitioner::RemoveTransition, false)) {
            translateAndTransitionItemsAfter(lastIndexInView, insertionPosChanges, removalPosChanges);
        }

        prepareVisibleItemTransitions();

        QRectF viewBounds(0, position(), q->width(), q->height());
        for (QList<FxViewItem*>::Iterator it = releasePendingTransition.begin();
             it != releasePendingTransition.end(); ) {
            FxViewItem *item = *it;
            if (prepareNonVisibleItemTransition(item, viewBounds)) {
                ++it;
            } else {
                releaseItem(item);
                it = releasePendingTransition.erase(it);
            }
        }

        for (int i=0; i<visibleItems.count(); i++)
            visibleItems[i]->startTransition(transitioner);
        for (int i=0; i<releasePendingTransition.count(); i++)
            releasePendingTransition[i]->startTransition(transitioner);

        transitioner->setPopulateTransitionEnabled(false);
        transitioner->resetTargetLists();
    }

    runDelayedRemoveTransition = false;
}

bool QQuickItemViewPrivate::applyModelChanges(ChangeResult *totalInsertionResult, ChangeResult *totalRemovalResult)
{
    Q_Q(QQuickItemView);
    if (!q->isComponentComplete() || (!currentChanges.hasPendingChanges() && !runDelayedRemoveTransition) || disableLayout)
        return false;

    disableLayout = true;

    updateUnrequestedIndexes();
    moveReason = QQuickItemViewPrivate::Other;

    FxViewItem *prevVisibleItemsFirst = visibleItems.count() ? *visibleItems.constBegin() : 0;
    int prevItemCount = itemCount;
    int prevVisibleItemsCount = visibleItems.count();
    bool visibleAffected = false;
    bool viewportChanged = !currentChanges.pendingChanges.removes().isEmpty()
            || !currentChanges.pendingChanges.inserts().isEmpty();

    FxViewItem *prevFirstVisible = firstVisibleItem();
    QQmlNullableValue<qreal> prevViewPos;
    int prevFirstVisibleIndex = -1;
    if (prevFirstVisible) {
        prevViewPos = prevFirstVisible->position();
        prevFirstVisibleIndex = prevFirstVisible->index;
    }
    qreal prevVisibleItemsFirstPos = visibleItems.count() ? visibleItems.first()->position() : 0.0;

    totalInsertionResult->visiblePos = prevViewPos;
    totalRemovalResult->visiblePos = prevViewPos;

    const QVector<QQuickChangeSet::Remove> &removals = currentChanges.pendingChanges.removes();
    const QVector<QQuickChangeSet::Insert> &insertions = currentChanges.pendingChanges.inserts();
    ChangeResult insertionResult(prevViewPos);
    ChangeResult removalResult(prevViewPos);

    int removedCount = 0;
    for (int i=0; i<removals.count(); i++) {
        itemCount -= removals[i].count;
        if (applyRemovalChange(removals[i], &removalResult, &removedCount))
            visibleAffected = true;
        if (!visibleAffected && needsRefillForAddedOrRemovedIndex(removals[i].index))
            visibleAffected = true;
        if (prevFirstVisibleIndex >= 0 && removals[i].index < prevFirstVisibleIndex) {
            if (removals[i].index + removals[i].count < prevFirstVisibleIndex)
                removalResult.countChangeBeforeVisible += removals[i].count;
            else
                removalResult.countChangeBeforeVisible += (prevFirstVisibleIndex - removals[i].index);
        }
    }
    if (runDelayedRemoveTransition) {
        QQuickChangeSet::Remove removal;
        for (QList<FxViewItem*>::Iterator it = visibleItems.begin(); it != visibleItems.end();) {
            FxViewItem *item = *it;
            if (item->index == -1 && !item->attached->delayRemove()) {
                removeItem(item, removal, &removalResult);
                removedCount++;
                it = visibleItems.erase(it);
            } else {
               ++it;
            }
        }
    }
    *totalRemovalResult += removalResult;
    if (!removals.isEmpty()) {
        updateVisibleIndex();

        // set positions correctly for the next insertion
        if (!insertions.isEmpty()) {
            repositionFirstItem(prevVisibleItemsFirst, prevVisibleItemsFirstPos, prevFirstVisible, &insertionResult, &removalResult);
            layoutVisibleItems(removals.first().index);
        }
    }

    QList<FxViewItem *> newItems;
    QList<MovedItem> movingIntoView;

    for (int i=0; i<insertions.count(); i++) {
        bool wasEmpty = visibleItems.isEmpty();
        if (applyInsertionChange(insertions[i], &insertionResult, &newItems, &movingIntoView))
            visibleAffected = true;
        if (!visibleAffected && needsRefillForAddedOrRemovedIndex(insertions[i].index))
            visibleAffected = true;
        if (wasEmpty && !visibleItems.isEmpty())
            resetFirstItemPosition();
        *totalInsertionResult += insertionResult;

        // set positions correctly for the next insertion
        if (i < insertions.count() - 1) {
            repositionFirstItem(prevVisibleItemsFirst, prevVisibleItemsFirstPos, prevFirstVisible, &insertionResult, &removalResult);
            layoutVisibleItems(insertions[i].index);
        }
        itemCount += insertions[i].count;
    }
    for (int i=0; i<newItems.count(); i++)
        newItems.at(i)->attached->emitAdd();

    // for each item that was moved directly into the view as a result of a move(),
    // find the index it was moved from in order to set its initial position, so that we
    // can transition it from this "original" position to its new position in the view
    if (transitioner && transitioner->canTransition(QQuickItemViewTransitioner::MoveTransition, true)) {
        for (int i=0; i<movingIntoView.count(); i++) {
            int fromIndex = findMoveKeyIndex(movingIntoView[i].moveKey, removals);
            if (fromIndex >= 0) {
                if (prevFirstVisibleIndex >= 0 && fromIndex < prevFirstVisibleIndex)
                    repositionItemAt(movingIntoView[i].item, fromIndex, -totalInsertionResult->sizeChangesAfterVisiblePos);
                else
                    repositionItemAt(movingIntoView[i].item, fromIndex, totalInsertionResult->sizeChangesAfterVisiblePos);
                movingIntoView[i].item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::MoveTransition, true);
            }
        }
    }

    // reposition visibleItems.first() correctly so that the content y doesn't jump
    if (removedCount != prevVisibleItemsCount)
        repositionFirstItem(prevVisibleItemsFirst, prevVisibleItemsFirstPos, prevFirstVisible, &insertionResult, &removalResult);

    // Whatever removed/moved items remain are no longer visible items.
    prepareRemoveTransitions(&currentChanges.removedItems);
    for (QHash<QQuickChangeSet::MoveKey, FxViewItem *>::Iterator it = currentChanges.removedItems.begin();
         it != currentChanges.removedItems.end(); ++it) {
        releaseItem(it.value());
    }
    currentChanges.removedItems.clear();

    if (currentChanges.currentChanged) {
        if (currentChanges.currentRemoved && currentItem) {
            currentItem->attached->setIsCurrentItem(false);
            releaseItem(currentItem);
            currentItem = 0;
        }
        if (!currentIndexCleared)
            updateCurrent(currentChanges.newCurrentIndex);
    }

    if (!visibleAffected)
        visibleAffected = !currentChanges.pendingChanges.changes().isEmpty();
    currentChanges.reset();

    updateSections();
    if (prevItemCount != itemCount)
        emit q->countChanged();
    if (!visibleAffected && viewportChanged)
        updateViewport();

    disableLayout = false;
    return visibleAffected;
}

bool QQuickItemViewPrivate::applyRemovalChange(const QQuickChangeSet::Remove &removal, ChangeResult *removeResult, int *removedCount)
{
    Q_Q(QQuickItemView);
    bool visibleAffected = false;

    if (visibleItems.count() && removal.index + removal.count > visibleItems.last()->index) {
        if (removal.index > visibleItems.last()->index)
            removeResult->countChangeAfterVisibleItems += removal.count;
        else
            removeResult->countChangeAfterVisibleItems += ((removal.index + removal.count - 1) - visibleItems.last()->index);
    }

    QList<FxViewItem*>::Iterator it = visibleItems.begin();
    while (it != visibleItems.end()) {
        FxViewItem *item = *it;
        if (item->index == -1 || item->index < removal.index) {
            // already removed, or before removed items
            if (!visibleAffected && item->index < removal.index)
                visibleAffected = true;
            ++it;
        } else if (item->index >= removal.index + removal.count) {
            // after removed items
            item->index -= removal.count;
            if (removal.isMove())
                item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::MoveTransition, false);
            else
                item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::RemoveTransition, false);
            ++it;
        } else {
            // removed item
            visibleAffected = true;
            if (!removal.isMove())
                item->attached->emitRemove();

            if (item->attached->delayRemove() && !removal.isMove()) {
                item->index = -1;
                QObject::connect(item->attached, SIGNAL(delayRemoveChanged()), q, SLOT(destroyRemoved()), Qt::QueuedConnection);
                ++it;
            } else {
                removeItem(item, removal, removeResult);
                if (!removal.isMove())
                    (*removedCount)++;
                it = visibleItems.erase(it);
            }
        }
    }

    return visibleAffected;
}

void QQuickItemViewPrivate::removeItem(FxViewItem *item, const QQuickChangeSet::Remove &removal, ChangeResult *removeResult)
{
    if (removeResult->visiblePos.isValid()) {
        if (item->position() < removeResult->visiblePos)
            removeResult->sizeChangesBeforeVisiblePos += item->size();
        else
            removeResult->sizeChangesAfterVisiblePos += item->size();
    }
    if (removal.isMove()) {
        currentChanges.removedItems.insert(removal.moveKey(item->index), item);
        item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::MoveTransition, true);
    } else {
        // track item so it is released later
        currentChanges.removedItems.insertMulti(QQuickChangeSet::MoveKey(), item);
    }
    if (!removeResult->changedFirstItem && item == *visibleItems.constBegin())
        removeResult->changedFirstItem = true;
}

void QQuickItemViewPrivate::repositionFirstItem(FxViewItem *prevVisibleItemsFirst,
                                                   qreal prevVisibleItemsFirstPos,
                                                   FxViewItem *prevFirstVisible,
                                                   ChangeResult *insertionResult,
                                                   ChangeResult *removalResult)
{
    const QQmlNullableValue<qreal> prevViewPos = insertionResult->visiblePos;

    // reposition visibleItems.first() correctly so that the content y doesn't jump
    if (visibleItems.count()) {
        if (prevVisibleItemsFirst && insertionResult->changedFirstItem)
            resetFirstItemPosition(prevVisibleItemsFirstPos);

        if (prevFirstVisible && prevVisibleItemsFirst == prevFirstVisible
                && prevFirstVisible != *visibleItems.constBegin()) {
            // the previous visibleItems.first() was also the first visible item, and it has been
            // moved/removed, so move the new visibleItems.first() to the pos of the previous one
            if (!insertionResult->changedFirstItem)
                resetFirstItemPosition(prevVisibleItemsFirstPos);

        } else if (prevViewPos.isValid()) {
            qreal moveForwardsBy = 0;
            qreal moveBackwardsBy = 0;

            // shift visibleItems.first() relative to the number of added/removed items
            if (visibleItems.first()->position() > prevViewPos) {
                moveForwardsBy = insertionResult->sizeChangesAfterVisiblePos;
                moveBackwardsBy = removalResult->sizeChangesAfterVisiblePos;
            } else if (visibleItems.first()->position() < prevViewPos) {
                moveForwardsBy = removalResult->sizeChangesBeforeVisiblePos;
                moveBackwardsBy = insertionResult->sizeChangesBeforeVisiblePos;
            }
            adjustFirstItem(moveForwardsBy, moveBackwardsBy, insertionResult->countChangeBeforeVisible - removalResult->countChangeBeforeVisible);
        }
        insertionResult->reset();
        removalResult->reset();
    }
}

void QQuickItemViewPrivate::createTransitioner()
{
    if (!transitioner) {
        transitioner = new QQuickItemViewTransitioner;
        transitioner->setChangeListener(this);
    }
}

void QQuickItemViewPrivate::prepareVisibleItemTransitions()
{
    Q_Q(QQuickItemView);
    if (!transitioner)
        return;

    // must call for every visible item to init or discard transitions
    QRectF viewBounds(0, position(), q->width(), q->height());
    for (int i=0; i<visibleItems.count(); i++)
        visibleItems[i]->prepareTransition(transitioner, viewBounds);
}

void QQuickItemViewPrivate::prepareRemoveTransitions(QHash<QQuickChangeSet::MoveKey, FxViewItem *> *removedItems)
{
    if (!transitioner)
        return;

    if (transitioner->canTransition(QQuickItemViewTransitioner::RemoveTransition, true)
            || transitioner->canTransition(QQuickItemViewTransitioner::RemoveTransition, false)) {
        for (QHash<QQuickChangeSet::MoveKey, FxViewItem *>::Iterator it = removedItems->begin();
             it != removedItems->end(); ) {
            bool isRemove = it.key().moveId < 0;
            if (isRemove) {
                FxViewItem *item = *it;
                item->releaseAfterTransition = true;
                releasePendingTransition.append(item);
                item->transitionNextReposition(transitioner, QQuickItemViewTransitioner::RemoveTransition, true);
                it = removedItems->erase(it);
            } else {
                ++it;
            }
        }
    }
}

bool QQuickItemViewPrivate::prepareNonVisibleItemTransition(FxViewItem *item, const QRectF &viewBounds)
{
    // Called for items that have been removed from visibleItems and may now be
    // transitioned out of the view. This applies to items that are being directly
    // removed, or moved to outside of the view, as well as those that are
    // displaced to a position outside of the view due to an insert or move.

    if (!transitioner)
        return false;

    if (item->scheduledTransitionType() == QQuickItemViewTransitioner::MoveTransition)
        repositionItemAt(item, item->index, 0);

    if (item->prepareTransition(transitioner, viewBounds)) {
        item->releaseAfterTransition = true;
        return true;
    }
    return false;
}

void QQuickItemViewPrivate::viewItemTransitionFinished(QQuickItemViewTransitionableItem *item)
{
    for (int i=0; i<releasePendingTransition.count(); i++) {
        if (releasePendingTransition[i]->transitionableItem == item) {
            releaseItem(releasePendingTransition.takeAt(i));
            return;
        }
    }
}

/*
  This may return 0 if the item is being created asynchronously.
  When the item becomes available, refill() will be called and the item
  will be returned on the next call to createItem().
*/
FxViewItem *QQuickItemViewPrivate::createItem(int modelIndex, bool asynchronous)
{
    Q_Q(QQuickItemView);

    if (requestedIndex == modelIndex && (asynchronous || requestedAsync == asynchronous))
        return 0;

    if (requestedIndex != -1 && requestedIndex != modelIndex) {
        if (requestedItem && requestedItem->item)
            requestedItem->item->setParentItem(0);
        delete requestedItem;
        requestedItem = 0;
    }

    for (int i=0; i<releasePendingTransition.count(); i++) {
        if (releasePendingTransition[i]->index == modelIndex
                && !releasePendingTransition[i]->isPendingRemoval()) {
            releasePendingTransition[i]->releaseAfterTransition = false;
            return releasePendingTransition.takeAt(i);
        }
    }

    requestedIndex = modelIndex;
    requestedAsync = asynchronous;
    inRequest = true;

    if (QQuickItem *item = model->item(modelIndex, asynchronous)) {
        item->setParentItem(q->contentItem());
        QQml_setParent_noEvent(item, q->contentItem());
        requestedIndex = -1;
        FxViewItem *viewItem = requestedItem;
        if (!viewItem)
            viewItem = newViewItem(modelIndex, item); // already in cache, so viewItem not initialized in initItem()
        if (viewItem) {
            viewItem->index = modelIndex;
            // do other set up for the new item that should not happen
            // until after bindings are evaluated
            initializeViewItem(viewItem);
            unrequestedItems.remove(item);
        }
        requestedItem = 0;
        inRequest = false;
        return viewItem;
    }

    inRequest = false;
    return 0;
}

void QQuickItemView::createdItem(int index, QQuickItem *item)
{
    Q_D(QQuickItemView);
    if (d->requestedIndex != index) {
        item->setParentItem(contentItem());
        d->unrequestedItems.insert(item, index);
        item->setVisible(false);
        d->repositionPackageItemAt(item, index);
    } else {
        d->requestedIndex = -1;
        if (!d->inRequest) {
            if (index == d->currentIndex)
                d->updateCurrent(index);
            d->refill();
        }
    }
}

void QQuickItemView::initItem(int index, QQuickItem *item)
{
    Q_D(QQuickItemView);
    item->setZ(1);
    if (d->requestedIndex == index) {
        if (d->requestedAsync)
            item->setVisible(false);
        item->setParentItem(contentItem());
        QQml_setParent_noEvent(item, contentItem());
        d->requestedItem = d->newViewItem(index, item);
    }
}

void QQuickItemView::destroyingItem(QQuickItem *item)
{
    Q_D(QQuickItemView);
    d->unrequestedItems.remove(item);
}

bool QQuickItemViewPrivate::releaseItem(FxViewItem *item)
{
    Q_Q(QQuickItemView);
    if (!item || !model)
        return true;
    if (trackedItem == item)
        trackedItem = 0;
    QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(item->item);
    itemPrivate->removeItemChangeListener(this, QQuickItemPrivate::Geometry);
    QQuickVisualModel::ReleaseFlags flags = model->release(item->item);
    if (flags == 0) {
        // item was not destroyed, and we no longer reference it.
        item->item->setVisible(false);
        unrequestedItems.insert(item->item, model->indexOf(item->item, q));
    }
    delete item;
    return flags != QQuickVisualModel::Referenced;
}

QQuickItem *QQuickItemViewPrivate::createHighlightItem()
{
    return createComponentItem(highlightComponent, true);
}

QQuickItem *QQuickItemViewPrivate::createComponentItem(QQmlComponent *component, bool createDefault)
{
    Q_Q(QQuickItemView);

    QQuickItem *item = 0;
    if (component) {
        QQmlContext *creationContext = component->creationContext();
        QQmlContext *context = new QQmlContext(
                creationContext ? creationContext : qmlContext(q));
        QObject *nobj = component->create(context);
        if (nobj) {
            QQml_setParent_noEvent(context, nobj);
            item = qobject_cast<QQuickItem *>(nobj);
            if (!item)
                delete nobj;
        } else {
            delete context;
        }
    } else if (createDefault) {
        item = new QQuickItem;
    }
    if (item) {
        QQml_setParent_noEvent(item, q->contentItem());
        item->setParentItem(q->contentItem());
    }
    return item;
}

void QQuickItemViewPrivate::updateTrackedItem()
{
    Q_Q(QQuickItemView);
    FxViewItem *item = currentItem;
    if (highlight)
        item = highlight;
    trackedItem = item;

    if (trackedItem)
        q->trackedPositionChanged();
}

void QQuickItemViewPrivate::updateUnrequestedIndexes()
{
    Q_Q(QQuickItemView);
    for (QHash<QQuickItem*,int>::iterator it = unrequestedItems.begin(); it != unrequestedItems.end(); ++it)
        *it = model->indexOf(it.key(), q);
}

void QQuickItemViewPrivate::updateUnrequestedPositions()
{
    for (QHash<QQuickItem*,int>::const_iterator it = unrequestedItems.begin(); it != unrequestedItems.end(); ++it)
        repositionPackageItemAt(it.key(), it.value());
}

void QQuickItemViewPrivate::updateVisibleIndex()
{
    visibleIndex = 0;
    for (QList<FxViewItem*>::Iterator it = visibleItems.begin(); it != visibleItems.end(); ++it) {
        if ((*it)->index != -1) {
            visibleIndex = (*it)->index;
            break;
        }
    }
}

QT_END_NAMESPACE