qquickpathview.cpp

Go to the documentation of this file.

// Copyright (C) 2019 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qquickpathview_p.h"
#include "qquickpathview_p_p.h"
#include "qquickflickablebehavior_p.h" //Contains flicking behavior defines
#include "qquicktext_p.h"
 
#include <QtQuick/private/qquickstate_p.h>
#include <private/qqmlglobal_p.h>
#include <private/qqmlopenmetaobject_p.h>
#include <private/qqmlchangeset_p.h>
#include <qpa/qplatformintegration.h>
 
#include <QtQml/qqmlinfo.h>
 
#include <QtGui/private/qeventpoint_p.h>
#include <QtGui/qevent.h>
#include <QtGui/qguiapplication.h>
#include <QtGui/private/qguiapplication_p.h>
#include <QtGui/qstylehints.h>
#include <QtCore/qmath.h>
 
#include <cmath>
 
QT_BEGIN_NAMESPACE
 
Q_DECLARE_LOGGING_CATEGORY(lcItemViewDelegateLifecycle)
#if !QT_CONFIG(quick_itemview)
Q_LOGGING_CATEGORY(lcItemViewDelegateLifecycle, "qt.quick.itemview.lifecycle")
#endif
Q_LOGGING_CATEGORY(lcPathView, "qt.quick.pathview")
 
static QQmlOpenMetaObjectType *qPathViewAttachedType = nullptr;
 
QQuickPathViewAttached::QQuickPathViewAttached(QObject *parent)
: QObject(parent), m_percent(-1), m_view(nullptr), m_onPath(false), m_isCurrent(false)
{
    if (qPathViewAttachedType) {
        m_metaobject = new QQmlOpenMetaObject(this, qPathViewAttachedType);
        m_metaobject->setCached(true);
    } else {
        m_metaobject = new QQmlOpenMetaObject(this);
    }
}
 
QQuickPathViewAttached::~QQuickPathViewAttached()
{
}
 
QVariant QQuickPathViewAttached::value(const QByteArray &name) const
{
    return m_metaobject->value(name);
}
void QQuickPathViewAttached::setValue(const QByteArray &name, const QVariant &val)
{
    m_metaobject->setValue(name, val);
}
 
QQuickPathViewPrivate::QQuickPathViewPrivate()
  : path(nullptr), currentIndex(0), currentItemOffset(0), startPc(0)
    , offset(0), offsetAdj(0), mappedRange(1), mappedCache(0)
    , stealMouse(false), ownModel(false), interactive(true), haveHighlightRange(true)
    , autoHighlight(true), highlightUp(false), layoutScheduled(false)
    , moving(false), flicking(false), dragging(false), inRequest(false), delegateValidated(false)
    , inRefill(false)
    , dragMargin(0), deceleration(100)
    , maximumFlickVelocity(QGuiApplicationPrivate::platformIntegration()->styleHint(QPlatformIntegration::FlickMaximumVelocity).toReal())
    , moveOffset(this, &QQuickPathViewPrivate::setAdjustedOffset), flickDuration(0)
    , pathItems(-1), requestedIndex(-1), cacheSize(0), requestedZ(0)
    , moveReason(Other), movementDirection(QQuickPathView::Shortest), moveDirection(QQuickPathView::Shortest)
    , attType(nullptr), highlightComponent(nullptr), highlightItem(nullptr)
    , moveHighlight(this, &QQuickPathViewPrivate::setHighlightPosition)
    , highlightPosition(0)
    , highlightRangeStart(0), highlightRangeEnd(0)
    , highlightRangeMode(QQuickPathView::StrictlyEnforceRange)
    , highlightMoveDuration(300), modelCount(0), snapMode(QQuickPathView::NoSnap)
{
}
 
void QQuickPathViewPrivate::init()
{
    Q_Q(QQuickPathView);
    offset = 0;
    q->setAcceptedMouseButtons(Qt::LeftButton);
    q->setFlag(QQuickItem::ItemIsFocusScope);
    q->setFiltersChildMouseEvents(true);
    qmlobject_connect(&tl, QQuickTimeLine, SIGNAL(updated()),
                      q, QQuickPathView, SLOT(ticked()));
    timer.invalidate();
    qmlobject_connect(&tl, QQuickTimeLine, SIGNAL(completed()),
                      q, QQuickPathView, SLOT(movementEnding()));
}
 
QQuickItem *QQuickPathViewPrivate::getItem(int modelIndex, qreal z, bool async)
{
    Q_Q(QQuickPathView);
    requestedIndex = modelIndex;
    requestedZ = z;
    inRequest = true;
    QObject *object = model->object(modelIndex, async ? QQmlIncubator::Asynchronous : QQmlIncubator::AsynchronousIfNested);
    QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
    if (!item) {
        if (object) {
            model->release(object);
            if (!delegateValidated) {
                delegateValidated = true;
                QObject* delegate = q->delegate();
                qmlWarning(delegate ? delegate : q) << QQuickPathView::tr("Delegate must be of Item type");
            }
        }
    } else {
        item->setParentItem(q);
        requestedIndex = -1;
        QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(item);
        itemPrivate->addItemChangeListener(
                    this, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
    }
    inRequest = false;
    return item;
}
 
void QQuickPathView::createdItem(int index, QObject *object)
{
    Q_D(QQuickPathView);
    QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
    if (d->requestedIndex != index) {
        qPathViewAttachedType = d->attachedType();
        QQuickPathViewAttached *att = static_cast<QQuickPathViewAttached *>(qmlAttachedPropertiesObject<QQuickPathView>(item));
        qPathViewAttachedType = nullptr;
        if (att) {
            att->m_view = this;
            att->setOnPath(false);
        }
        item->setParentItem(this);
        d->updateItem(item, 1);
    } else {
        d->requestedIndex = -1;
        if (!d->inRequest)
            refill();
    }
}
 
void QQuickPathView::initItem(int index, QObject *object)
{
    Q_D(QQuickPathView);
    QQuickItem *item = qmlobject_cast<QQuickItem*>(object);
    if (item && d->requestedIndex == index) {
        QQuickItemPrivate::get(item)->setCulled(true);
        item->setParentItem(this);
        qPathViewAttachedType = d->attachedType();
        QQuickPathViewAttached *att = static_cast<QQuickPathViewAttached *>(qmlAttachedPropertiesObject<QQuickPathView>(item));
        qPathViewAttachedType = nullptr;
        if (att) {
            att->m_view = this;
            qreal percent = d->positionOfIndex(index);
            if (percent < 1 && d->path) {
                const auto attributes = d->path->attributes();
                for (const QString &attr : attributes)
                    att->setValue(attr.toUtf8(), d->path->attributeAt(attr, percent));
                item->setZ(d->requestedZ);
            }
            att->setOnPath(percent < 1);
        }
    }
}
 
void QQuickPathViewPrivate::releaseItem(QQuickItem *item)
{
    if (!item)
        return;
    qCDebug(lcItemViewDelegateLifecycle) << "release" << item;
    QQuickItemPrivate *itemPrivate = QQuickItemPrivate::get(item);
    itemPrivate->removeItemChangeListener(
                this, QQuickItemPrivate::Geometry | QQuickItemPrivate::Destroyed);
    if (!model)
        return;
    QQmlInstanceModel::ReleaseFlags flags = model->release(item);
    if (!flags) {
        // item was not destroyed, and we no longer reference it.
        if (QQuickPathViewAttached *att = attached(item))
            att->setOnPath(false);
    } else if (flags & QQmlInstanceModel::Destroyed) {
        // but we still reference it
        item->setParentItem(nullptr);
    }
}
 
QQuickPathViewAttached *QQuickPathViewPrivate::attached(QQuickItem *item)
{
    return static_cast<QQuickPathViewAttached *>(qmlAttachedPropertiesObject<QQuickPathView>(item, false));
}
 
QQmlOpenMetaObjectType *QQuickPathViewPrivate::attachedType()
{
    if (!attType) {
        // pre-create one metatype to share with all attached objects
        attType = new QQmlOpenMetaObjectType(&QQuickPathViewAttached::staticMetaObject);
        if (path) {
            const auto attributes = path->attributes();
            for (const QString &attr : attributes)
                attType->createProperty(attr.toUtf8());
        }
    }
 
    return attType;
}
 
void QQuickPathViewPrivate::clear()
{
    if (currentItem) {
        releaseItem(currentItem);
        currentItem = nullptr;
    }
 
    for (QQuickItem *p : std::as_const(items))
        releaseItem(p);
 
    for (QQuickItem *p : std::as_const(itemCache))
        releaseItem(p);
 
    if (requestedIndex >= 0) {
        if (model)
            model->cancel(requestedIndex);
        requestedIndex = -1;
    }
 
    items.clear();
    itemCache.clear();
    tl.clear();
}
 
void QQuickPathViewPrivate::updateMappedRange()
{
    if (model && pathItems != -1 && pathItems < modelCount) {
        mappedRange = qreal(modelCount)/pathItems;
        mappedCache = qreal(cacheSize)/pathItems/2; // Half of cache at each end
    } else {
        mappedRange = 1;
        mappedCache = 0;
    }
}
 
qreal QQuickPathViewPrivate::positionOfIndex(qreal index) const
{
    qreal pos = -1;
 
    if (model && index >= 0 && index < modelCount) {
        qreal start = 0;
        if (haveHighlightRange && (highlightRangeMode != QQuickPathView::NoHighlightRange
                                   || snapMode != QQuickPathView::NoSnap))
            start = highlightRangeStart;
        qreal globalPos = index + offset;
        globalPos = std::fmod(globalPos, qreal(modelCount)) / modelCount;
        if (pathItems != -1 && pathItems < modelCount) {
            globalPos += start / mappedRange;
            globalPos = std::fmod(globalPos, qreal(1));
            pos = globalPos * mappedRange;
        } else {
            pos = std::fmod(globalPos + start, qreal(1));
        }
    }
 
    return pos;
}
 
// returns true if position is between lower and upper, taking into
// account the circular space.
bool QQuickPathViewPrivate::isInBound(qreal position, qreal lower, qreal upper) const
{
    if (qFuzzyCompare(lower, upper))
        return true;
    if (lower > upper) {
        if (position > upper && position > lower)
            position -= mappedRange;
        lower -= mappedRange;
    }
    return position >= lower && position < upper;
}
 
void QQuickPathViewPrivate::createHighlight()
{
    Q_Q(QQuickPathView);
    if (!q->isComponentComplete())
        return;
 
    bool changed = false;
    if (highlightItem) {
        highlightItem->setParentItem(nullptr);
        highlightItem->deleteLater();
        highlightItem = nullptr;
        changed = true;
    }
 
    QQuickItem *item = nullptr;
    if (highlightComponent) {
        QQmlContext *creationContext = highlightComponent->creationContext();
        QQmlContext *highlightContext = new QQmlContext(
                creationContext ? creationContext : qmlContext(q));
        QObject *nobj = highlightComponent->create(highlightContext);
        if (nobj) {
            QQml_setParent_noEvent(highlightContext, nobj);
            item = qobject_cast<QQuickItem *>(nobj);
            if (!item)
                delete nobj;
        } else {
            delete highlightContext;
        }
    } else {
        item = new QQuickItem;
    }
    if (item) {
        QQml_setParent_noEvent(item, q);
        item->setParentItem(q);
        highlightItem = item;
        changed = true;
    }
    if (changed)
        emit q->highlightItemChanged();
}
 
void QQuickPathViewPrivate::updateHighlight()
{
    Q_Q(QQuickPathView);
    if (!q->isComponentComplete() || !isValid())
        return;
    if (highlightItem) {
        if (haveHighlightRange && highlightRangeMode == QQuickPathView::StrictlyEnforceRange) {
            updateItem(highlightItem, highlightRangeStart);
        } else {
            qreal target = currentIndex;
 
            offsetAdj = 0;
            tl.reset(moveHighlight);
            moveHighlight.setValue(highlightPosition);
 
            const int duration = highlightMoveDuration;
 
            if (target - highlightPosition > modelCount/2) {
                highlightUp = false;
                qreal distance = modelCount - target + highlightPosition;
                tl.move(moveHighlight, 0, QEasingCurve(QEasingCurve::InQuad), int(duration * highlightPosition / distance));
                tl.set(moveHighlight, modelCount-0.01);
                tl.move(moveHighlight, target, QEasingCurve(QEasingCurve::OutQuad), int(duration * (modelCount-target) / distance));
            } else if (target - highlightPosition <= -modelCount/2) {
                highlightUp = true;
                qreal distance = modelCount - highlightPosition + target;
                tl.move(moveHighlight, modelCount-0.01, QEasingCurve(QEasingCurve::InQuad), int(duration * (modelCount-highlightPosition) / distance));
                tl.set(moveHighlight, 0);
                tl.move(moveHighlight, target, QEasingCurve(QEasingCurve::OutQuad), int(duration * target / distance));
            } else {
                highlightUp = highlightPosition - target < 0;
                tl.move(moveHighlight, target, QEasingCurve(QEasingCurve::InOutQuad), duration);
            }
        }
    }
}
 
void QQuickPathViewPrivate::setHighlightPosition(qreal pos)
{
    if (!(qFuzzyCompare(pos, highlightPosition))) {
        qreal start = 0;
        qreal end = 1;
        if (haveHighlightRange && highlightRangeMode != QQuickPathView::NoHighlightRange) {
            start = highlightRangeStart;
            end = highlightRangeEnd;
        }
 
        qreal range = qreal(modelCount);
        // calc normalized position of highlight relative to offset
        qreal relativeHighlight = std::fmod(pos + offset, range) / range;
 
        if (!highlightUp && relativeHighlight > end / mappedRange) {
            qreal diff = 1 - relativeHighlight;
            setOffset(offset + diff * range);
        } else if (highlightUp && relativeHighlight >= (end - start) / mappedRange) {
            qreal diff = relativeHighlight - (end - start) / mappedRange;
            setOffset(offset - diff * range - 0.00001);
        }
 
        highlightPosition = pos;
        qreal pathPos = positionOfIndex(pos);
        updateItem(highlightItem, pathPos);
        if (QQuickPathViewAttached *att = attached(highlightItem))
            att->setOnPath(pathPos < 1);
    }
}
 
void QQuickPathView::pathUpdated()
{
    Q_D(QQuickPathView);
    for (QQuickItem *item : std::as_const(d->items)) {
        if (QQuickPathViewAttached *att = d->attached(item))
            att->m_percent = -1;
    }
    refill();
}
 
void QQuickPathViewPrivate::updateItem(QQuickItem *item, qreal percent)
{
    if (!path)
        return;
    if (QQuickPathViewAttached *att = attached(item)) {
        if (qFuzzyCompare(att->m_percent, percent))
            return;
        att->m_percent = percent;
        const auto attributes = path->attributes();
        for (const QString &attr : attributes)
            att->setValue(attr.toUtf8(), path->attributeAt(attr, percent));
        att->setOnPath(percent < 1);
    }
    QQuickItemPrivate::get(item)->setCulled(percent >= 1);
    QPointF pf = path->pointAtPercent(qMin(percent, qreal(1)));
    item->setX(pf.x() - item->width()/2);
    item->setY(pf.y() - item->height()/2);
}
 
void QQuickPathViewPrivate::regenerate()
{
    Q_Q(QQuickPathView);
    if (!q->isComponentComplete())
        return;
 
    clear();
 
    if (!isValid())
        return;
 
    updateMappedRange();
    q->refill();
}
 
void QQuickPathViewPrivate::setDragging(bool d)
{
    Q_Q(QQuickPathView);
    if (dragging == d)
        return;
 
    dragging = d;
    if (dragging)
        emit q->dragStarted();
    else
        emit q->dragEnded();
 
    emit q->draggingChanged();
}
 
QQuickPathView::QQuickPathView(QQuickItem *parent)
  : QQuickItem(*(new QQuickPathViewPrivate), parent)
{
    Q_D(QQuickPathView);
    d->init();
}
 
QQuickPathView::~QQuickPathView()
{
    Q_D(QQuickPathView);
    d->clear();
    if (d->attType)
        d->attType->release();
    if (d->ownModel)
        delete d->model;
}
 
QVariant QQuickPathView::model() const
{
    Q_D(const QQuickPathView);
    return d->modelVariant;
}
 
void QQuickPathView::setModel(const QVariant &m)
{
    Q_D(QQuickPathView);
    QVariant model = m;
    if (model.userType() == qMetaTypeId<QJSValue>())
        model = model.value<QJSValue>().toVariant();
 
    if (d->modelVariant == model)
        return;
 
    if (d->model) {
        qmlobject_disconnect(d->model, QQmlInstanceModel, SIGNAL(modelUpdated(QQmlChangeSet,bool)),
                             this, QQuickPathView, SLOT(modelUpdated(QQmlChangeSet,bool)));
        qmlobject_disconnect(d->model, QQmlInstanceModel, SIGNAL(createdItem(int,QObject*)),
                             this, QQuickPathView, SLOT(createdItem(int,QObject*)));
        qmlobject_disconnect(d->model, QQmlInstanceModel, SIGNAL(initItem(int,QObject*)),
                             this, QQuickPathView, SLOT(initItem(int,QObject*)));
        d->clear();
    }
 
    d->modelVariant = model;
    QObject *object = qvariant_cast<QObject*>(model);
    QQmlInstanceModel *vim = nullptr;
    if (object && (vim = qobject_cast<QQmlInstanceModel *>(object))) {
        if (d->ownModel) {
            delete d->model;
            d->ownModel = false;
        }
        d->model = vim;
    } else {
        if (!d->ownModel) {
            d->model = new QQmlDelegateModel(qmlContext(this));
            d->ownModel = true;
            if (isComponentComplete())
                static_cast<QQmlDelegateModel *>(d->model.data())->componentComplete();
        }
        if (QQmlDelegateModel *dataModel = qobject_cast<QQmlDelegateModel*>(d->model))
            dataModel->setModel(model);
    }
    int oldModelCount = d->modelCount;
    d->modelCount = 0;
    if (d->model) {
        qmlobject_connect(d->model, QQmlInstanceModel, SIGNAL(modelUpdated(QQmlChangeSet,bool)),
                          this, QQuickPathView, SLOT(modelUpdated(QQmlChangeSet,bool)));
        qmlobject_connect(d->model, QQmlInstanceModel, SIGNAL(createdItem(int,QObject*)),
                          this, QQuickPathView, SLOT(createdItem(int,QObject*)));
        qmlobject_connect(d->model, QQmlInstanceModel, SIGNAL(initItem(int,QObject*)),
                          this, QQuickPathView, SLOT(initItem(int,QObject*)));
        d->modelCount = d->model->count();
    }
    if (isComponentComplete()) {
        if (d->currentIndex != 0) {
            d->currentIndex = 0;
            emit currentIndexChanged();
        }
        if (!(qFuzzyIsNull(d->offset))) {
            d->offset = 0;
            emit offsetChanged();
        }
    }
    d->regenerate();
    if (d->modelCount != oldModelCount)
        emit countChanged();
    emit modelChanged();
}
 
int QQuickPathView::count() const
{
    Q_D(const QQuickPathView);
    return d->model ? d->modelCount : 0;
}
 
QQuickPath *QQuickPathView::path() const
{
    Q_D(const QQuickPathView);
    return d->path;
}
 
void QQuickPathView::setPath(QQuickPath *path)
{
    Q_D(QQuickPathView);
    if (d->path == path)
        return;
    if (d->path)
        qmlobject_disconnect(d->path, QQuickPath, SIGNAL(changed()),
                             this, QQuickPathView, SLOT(pathUpdated()));
    d->path = path;
 
    if (path) {
        qmlobject_connect(d->path, QQuickPath, SIGNAL(changed()),
                          this, QQuickPathView, SLOT(pathUpdated()));
    }
 
    if (isComponentComplete()) {
        d->clear();
        if (d->isValid()) {
            if (d->attType) {
                d->attType->release();
                d->attType = nullptr;
            }
            d->regenerate();
        }
    }
 
    emit pathChanged();
}
 
int QQuickPathView::currentIndex() const
{
    Q_D(const QQuickPathView);
    return d->currentIndex;
}
 
void QQuickPathView::setCurrentIndex(int idx)
{
    Q_D(QQuickPathView);
    if (!isComponentComplete()) {
        if (idx != d->currentIndex) {
            d->currentIndex = idx;
            emit currentIndexChanged();
        }
        return;
    }
 
    idx = d->modelCount
        ? ((idx % d->modelCount) + d->modelCount) % d->modelCount
        : 0;
    if (d->model && (idx != d->currentIndex || !d->currentItem)) {
        if (d->currentItem) {
            if (QQuickPathViewAttached *att = d->attached(d->currentItem))
                att->setIsCurrentItem(false);
            d->releaseItem(d->currentItem);
        }
        int oldCurrentIdx = d->currentIndex;
        QQuickItem *oldCurrentItem = d->currentItem;
        d->currentItem = nullptr;
        d->moveReason = QQuickPathViewPrivate::SetIndex;
        d->currentIndex = idx;
        if (d->modelCount) {
            d->createCurrentItem();
            if (d->haveHighlightRange && d->highlightRangeMode == QQuickPathView::StrictlyEnforceRange)
                d->snapToIndex(d->currentIndex, QQuickPathViewPrivate::SetIndex);
            d->currentItemOffset = d->positionOfIndex(d->currentIndex);
            d->updateHighlight();
        }
        if (oldCurrentIdx != d->currentIndex)
            emit currentIndexChanged();
        if (oldCurrentItem != d->currentItem)
            emit currentItemChanged();
    }
}
 
QQuickItem *QQuickPathView::currentItem() const
{
    Q_D(const QQuickPathView);
    return d->currentItem;
}
 
void QQuickPathView::incrementCurrentIndex()
{
    Q_D(QQuickPathView);
    d->moveDirection = QQuickPathView::Positive;
    setCurrentIndex(currentIndex()+1);
}
 
void QQuickPathView::decrementCurrentIndex()
{
    Q_D(QQuickPathView);
    d->moveDirection = QQuickPathView::Negative;
    setCurrentIndex(currentIndex()-1);
}
 
qreal QQuickPathView::offset() const
{
    Q_D(const QQuickPathView);
    return d->offset;
}
 
void QQuickPathView::setOffset(qreal offset)
{
    Q_D(QQuickPathView);
    d->moveReason = QQuickPathViewPrivate::Other;
    d->setOffset(offset);
    d->updateCurrent();
}
 
void QQuickPathViewPrivate::setOffset(qreal o)
{
    Q_Q(QQuickPathView);
    if (!qFuzzyCompare(offset, o)) {
        if (isValid() && q->isComponentComplete()) {
            qreal oldOffset = offset;
            offset = std::fmod(o, qreal(modelCount));
            if (offset < 0)
                offset += qreal(modelCount);
            qCDebug(lcItemViewDelegateLifecycle) << o << "was" << oldOffset << "now" << offset;
            q->refill();
        } else {
            offset = o;
        }
        emit q->offsetChanged();
    }
}
 
void QQuickPathViewPrivate::setAdjustedOffset(qreal o)
{
    setOffset(o+offsetAdj);
}
 
QQmlComponent *QQuickPathView::highlight() const
{
    Q_D(const QQuickPathView);
    return d->highlightComponent;
}
 
void QQuickPathView::setHighlight(QQmlComponent *highlight)
{
    Q_D(QQuickPathView);
    if (highlight != d->highlightComponent) {
        d->highlightComponent = highlight;
        d->createHighlight();
        d->updateHighlight();
        emit highlightChanged();
    }
}
 
QQuickItem *QQuickPathView::highlightItem() const
{
    Q_D(const QQuickPathView);
    return d->highlightItem;
}
 
qreal QQuickPathView::preferredHighlightBegin() const
{
    Q_D(const QQuickPathView);
    return d->highlightRangeStart;
}
 
void QQuickPathView::setPreferredHighlightBegin(qreal start)
{
    Q_D(QQuickPathView);
    if (qFuzzyCompare(d->highlightRangeStart, start) || start < 0 || start > 1)
        return;
    d->highlightRangeStart = start;
    d->haveHighlightRange = d->highlightRangeStart <= d->highlightRangeEnd;
    refill();
    emit preferredHighlightBeginChanged();
}
 
qreal QQuickPathView::preferredHighlightEnd() const
{
    Q_D(const QQuickPathView);
    return d->highlightRangeEnd;
}
 
void QQuickPathView::setPreferredHighlightEnd(qreal end)
{
    Q_D(QQuickPathView);
    if (qFuzzyCompare(d->highlightRangeEnd, end) || end < 0 || end > 1)
        return;
    d->highlightRangeEnd = end;
    d->haveHighlightRange = d->highlightRangeStart <= d->highlightRangeEnd;
    refill();
    emit preferredHighlightEndChanged();
}
 
QQuickPathView::HighlightRangeMode QQuickPathView::highlightRangeMode() const
{
    Q_D(const QQuickPathView);
    return d->highlightRangeMode;
}
 
void QQuickPathView::setHighlightRangeMode(HighlightRangeMode mode)
{
    Q_D(QQuickPathView);
    if (d->highlightRangeMode == mode)
        return;
    d->highlightRangeMode = mode;
    d->haveHighlightRange = d->highlightRangeStart <= d->highlightRangeEnd;
    if (d->haveHighlightRange) {
        d->regenerate();
        int index = d->highlightRangeMode != NoHighlightRange ? d->currentIndex : d->calcCurrentIndex();
        if (index >= 0)
            d->snapToIndex(index, QQuickPathViewPrivate::Other);
    }
    emit highlightRangeModeChanged();
}
 
int QQuickPathView::highlightMoveDuration() const
{
    Q_D(const QQuickPathView);
    return d->highlightMoveDuration;
}
 
void QQuickPathView::setHighlightMoveDuration(int duration)
{
    Q_D(QQuickPathView);
    if (d->highlightMoveDuration == duration)
        return;
    d->highlightMoveDuration = duration;
    emit highlightMoveDurationChanged();
}
 
qreal QQuickPathView::dragMargin() const
{
    Q_D(const QQuickPathView);
    return d->dragMargin;
}
 
void QQuickPathView::setDragMargin(qreal dragMargin)
{
    Q_D(QQuickPathView);
    if (qFuzzyCompare(d->dragMargin, dragMargin))
        return;
    d->dragMargin = dragMargin;
    emit dragMarginChanged();
}
 
qreal QQuickPathView::flickDeceleration() const
{
    Q_D(const QQuickPathView);
    return d->deceleration;
}
 
void QQuickPathView::setFlickDeceleration(qreal dec)
{
    Q_D(QQuickPathView);
    if (qFuzzyCompare(d->deceleration, dec))
        return;
    d->deceleration = dec;
    emit flickDecelerationChanged();
}
 
qreal QQuickPathView::maximumFlickVelocity() const
{
    Q_D(const QQuickPathView);
    return d->maximumFlickVelocity;
}
 
void QQuickPathView::setMaximumFlickVelocity(qreal vel)
{
    Q_D(QQuickPathView);
    if (qFuzzyCompare(vel, d->maximumFlickVelocity))
        return;
    d->maximumFlickVelocity = vel;
    emit maximumFlickVelocityChanged();
}
 
 
bool QQuickPathView::isInteractive() const
{
    Q_D(const QQuickPathView);
    return d->interactive;
}
 
void QQuickPathView::setInteractive(bool interactive)
{
    Q_D(QQuickPathView);
    if (interactive != d->interactive) {
        d->interactive = interactive;
        if (!interactive)
            d->tl.clear();
        emit interactiveChanged();
    }
}
 
bool QQuickPathView::isMoving() const
{
    Q_D(const QQuickPathView);
    return d->moving;
}
 
bool QQuickPathView::isFlicking() const
{
    Q_D(const QQuickPathView);
    return d->flicking;
}
 
bool QQuickPathView::isDragging() const
{
    Q_D(const QQuickPathView);
    return d->dragging;
}
 
QQmlComponent *QQuickPathView::delegate() const
{
    Q_D(const QQuickPathView);
     if (d->model) {
        if (QQmlDelegateModel *dataModel = qobject_cast<QQmlDelegateModel*>(d->model))
            return dataModel->delegate();
    }
 
    return nullptr;
}
 
void QQuickPathView::setDelegate(QQmlComponent *delegate)
{
    Q_D(QQuickPathView);
    if (delegate == this->delegate())
        return;
    if (!d->ownModel) {
        d->model = new QQmlDelegateModel(qmlContext(this));
        d->ownModel = true;
        if (isComponentComplete())
            static_cast<QQmlDelegateModel *>(d->model.data())->componentComplete();
    }
    if (QQmlDelegateModel *dataModel = qobject_cast<QQmlDelegateModel*>(d->model)) {
        int oldCount = dataModel->count();
        dataModel->setDelegate(delegate);
        d->modelCount = dataModel->count();
        d->regenerate();
        if (oldCount != dataModel->count())
            emit countChanged();
        emit delegateChanged();
        d->delegateValidated = false;
    }
}
 
int QQuickPathView::pathItemCount() const
{
    Q_D(const QQuickPathView);
    return d->pathItems;
}
 
void QQuickPathView::setPathItemCount(int i)
{
    Q_D(QQuickPathView);
    if (i == d->pathItems)
        return;
    if (i < 1)
        i = 1;
    d->pathItems = i;
    d->updateMappedRange();
    if (d->isValid() && isComponentComplete()) {
        d->regenerate();
    }
    emit pathItemCountChanged();
}
 
void QQuickPathView::resetPathItemCount()
{
    Q_D(QQuickPathView);
    if (-1 == d->pathItems)
        return;
    d->pathItems = -1;
    d->updateMappedRange();
    if (d->isValid() && isComponentComplete())
        d->regenerate();
    emit pathItemCountChanged();
}
 
int QQuickPathView::cacheItemCount() const
{
    Q_D(const QQuickPathView);
    return d->cacheSize;
}
 
void QQuickPathView::setCacheItemCount(int i)
{
    Q_D(QQuickPathView);
    if (i == d->cacheSize || i < 0)
        return;
 
    d->cacheSize = i;
    d->updateMappedRange();
    refill();
    emit cacheItemCountChanged();
}
 
QQuickPathView::SnapMode QQuickPathView::snapMode() const
{
    Q_D(const QQuickPathView);
    return d->snapMode;
}
 
void QQuickPathView::setSnapMode(SnapMode mode)
{
    Q_D(QQuickPathView);
    if (mode == d->snapMode)
        return;
    d->snapMode = mode;
    emit snapModeChanged();
}
 
QQuickPathView::MovementDirection QQuickPathView::movementDirection() const
{
    Q_D(const QQuickPathView);
    return d->movementDirection;
}
 
void QQuickPathView::setMovementDirection(QQuickPathView::MovementDirection dir)
{
    Q_D(QQuickPathView);
    if (dir == d->movementDirection)
        return;
    d->movementDirection = dir;
    if (!d->tl.isActive())
        d->moveDirection = d->movementDirection;
    emit movementDirectionChanged();
}
 
void QQuickPathView::positionViewAtIndex(int index, int mode)
{
    Q_D(QQuickPathView);
    if (!d->isValid())
        return;
    if (mode < QQuickPathView::Beginning || mode > QQuickPathView::SnapPosition || mode == 3) // 3 is unused in PathView
        return;
 
    if (mode == QQuickPathView::Contain && (d->pathItems < 0 || d->modelCount <= d->pathItems))
        return;
 
    int count = d->pathItems == -1 ? d->modelCount : qMin(d->pathItems, d->modelCount);
    int idx = (index+d->modelCount) % d->modelCount;
    bool snap = d->haveHighlightRange && (d->highlightRangeMode != QQuickPathView::NoHighlightRange
            || d->snapMode != QQuickPathView::NoSnap);
 
    qreal beginOffset;
    qreal endOffset;
    if (snap) {
        beginOffset = d->modelCount - idx - qFloor(count * d->highlightRangeStart);
        endOffset = beginOffset + count - 1;
    } else {
        beginOffset = d->modelCount - idx;
        // Small offset since the last point coincides with the first and
        // this the only "end" position that gives the expected visual result.
        qreal adj = sizeof(qreal) == sizeof(float) ? 0.00001f : 0.000000000001;
        endOffset = std::fmod(beginOffset + count, qreal(d->modelCount)) - adj;
    }
    qreal offset = d->offset;
    switch (mode) {
    case Beginning:
        offset = beginOffset;
        break;
    case End:
        offset = endOffset;
        break;
    case Center:
        if (beginOffset < endOffset)
            offset = (beginOffset + endOffset)/2;
        else
            offset = (beginOffset + (endOffset + d->modelCount))/2;
        if (snap)
            offset = qRound(offset);
        break;
    case Contain:
        if ((beginOffset < endOffset && (d->offset < beginOffset || d->offset > endOffset))
                || (d->offset < beginOffset && d->offset > endOffset)) {
            qreal diff1 = std::fmod(beginOffset - d->offset + d->modelCount, qreal(d->modelCount));
            qreal diff2 = std::fmod(d->offset - endOffset + d->modelCount, qreal(d->modelCount));
            if (diff1 < diff2)
                offset = beginOffset;
            else
                offset = endOffset;
        }
        break;
    case SnapPosition:
        offset = d->modelCount - idx;
        break;
    }
 
    d->tl.clear();
    setOffset(offset);
}
 
int QQuickPathView::indexAt(qreal x, qreal y) const
{
    Q_D(const QQuickPathView);
    QQuickItem *item = itemAt(x, y);
    return item ? d->model->indexOf(item, nullptr) : -1;
}
 
QQuickItem *QQuickPathView::itemAt(qreal x, qreal y) const
{
    Q_D(const QQuickPathView);
    if (!d->isValid())
        return nullptr;
 
    for (QQuickItem *item : d->items) {
        QPointF p = item->mapFromItem(this, QPointF(x, y));
        if (item->contains(p))
            return item;
    }
 
    return nullptr;
}
 
QQuickItem *QQuickPathView::itemAtIndex(int index) const
{
    Q_D(const QQuickPathView);
    if (!d->isValid())
        return nullptr;
 
    for (QQuickItem *item : d->items) {
        if (index ==  d->model->indexOf(item, nullptr))
            return item;
    }
 
    return nullptr;
}
 
QPointF QQuickPathViewPrivate::pointNear(const QPointF &point, qreal *nearPercent) const
{
    const auto pathLength = path->path().length();
    qreal samples = qMin(pathLength / 5, qreal(500));
    qreal res = pathLength / samples;
 
    qreal mindist = 1e10; // big number
    QPointF nearPoint = path->pointAtPercent(0);
    qreal nearPc = 0;
 
    // get rough pos
    for (qreal i=1; i < samples; i++) {
        QPointF pt = path->pointAtPercent(i/samples);
        QPointF diff = pt - point;
        qreal dist = diff.x()*diff.x() + diff.y()*diff.y();
        if (dist < mindist) {
            nearPoint = pt;
            nearPc = i;
            mindist = dist;
        }
    }
 
    // now refine
    qreal approxPc = nearPc;
    for (qreal i = approxPc-1; i < approxPc+1; i += 1/(2*res)) {
        QPointF pt = path->pointAtPercent(i/samples);
        QPointF diff = pt - point;
        qreal dist = diff.x()*diff.x() + diff.y()*diff.y();
        if (dist < mindist) {
            nearPoint = pt;
            nearPc = i;
            mindist = dist;
        }
    }
 
    if (nearPercent)
        *nearPercent = nearPc / samples;
 
    return nearPoint;
}
 
void QQuickPathViewPrivate::addVelocitySample(qreal v)
{
    velocityBuffer.append(v);
    if (velocityBuffer.count() > QML_FLICK_SAMPLEBUFFER)
        velocityBuffer.remove(0);
    qCDebug(lcPathView) << "instantaneous velocity" << v;
}
 
qreal QQuickPathViewPrivate::calcVelocity() const
{
    qreal velocity = 0;
    if (velocityBuffer.count() > QML_FLICK_DISCARDSAMPLES) {
        int count = velocityBuffer.count()-QML_FLICK_DISCARDSAMPLES;
        for (int i = 0; i < count; ++i) {
            qreal v = velocityBuffer.at(i);
            velocity += v;
        }
        velocity /= count;
        qCDebug(lcPathView) << "average velocity" << velocity << "based on" << count << "samples";
    }
    return velocity;
}
 
qint64 QQuickPathViewPrivate::computeCurrentTime(QInputEvent *event) const
{
    if (0 != event->timestamp())
        return qint64(event->timestamp());
    return timer.elapsed();
}
 
void QQuickPathView::mousePressEvent(QMouseEvent *event)
{
    Q_D(QQuickPathView);
    if (d->interactive) {
        d->handleMousePressEvent(event);
        event->accept();
    } else {
        QQuickItem::mousePressEvent(event);
    }
}
 
void QQuickPathViewPrivate::handleMousePressEvent(QMouseEvent *event)
{
    Q_Q(QQuickPathView);
    if (!interactive || !items.size() || !model || !modelCount)
        return;
    velocityBuffer.clear();
    int idx = 0;
    for (; idx < items.size(); ++idx) {
        QQuickItem *item = items.at(idx);
        if (item->contains(item->mapFromScene(event->scenePosition())))
            break;
    }
    if (idx == items.size() && qFuzzyIsNull(dragMargin))  // didn't click on an item
        return;
 
    startPoint = pointNear(event->position(), &startPc);
    startPos = event->position();
    if (idx == items.size()) {
        qreal distance = qAbs(event->position().x() - startPoint.x()) + qAbs(event->position().y() - startPoint.y());
        if (distance > dragMargin)
            return;
    }
 
    if (tl.isActive() && flicking && flickDuration && qreal(tl.time()) / flickDuration < 0.8) {
        stealMouse = true; // If we've been flicked then steal the click.
        q->grabMouse(); // grab it right now too, just to be sure (QTBUG-77173)
    } else {
        stealMouse = false;
    }
    q->setKeepMouseGrab(stealMouse);
 
    timer.start();
    lastPosTime = computeCurrentTime(event);
    tl.clear();
}
 
void QQuickPathView::mouseMoveEvent(QMouseEvent *event)
{
    Q_D(QQuickPathView);
    if (d->interactive) {
        d->handleMouseMoveEvent(event);
        event->accept();
    } else {
        QQuickItem::mouseMoveEvent(event);
    }
}
 
void QQuickPathViewPrivate::handleMouseMoveEvent(QMouseEvent *event)
{
    Q_Q(QQuickPathView);
    if (!interactive || !timer.isValid() || !model || !modelCount)
        return;
 
    qint64 currentTimestamp = computeCurrentTime(event);
    qreal newPc;
    QPointF pathPoint = pointNear(event->position(), &newPc);
    if (!stealMouse) {
        QPointF posDelta = event->position() - startPos;
        if (QQuickDeliveryAgentPrivate::dragOverThreshold(posDelta.y(), Qt::YAxis, event) ||
                QQuickDeliveryAgentPrivate::dragOverThreshold(posDelta.x(), Qt::XAxis, event)) {
            // The touch has exceeded the threshold. If the movement along the path is close to the drag threshold
            // then we'll assume that this gesture targets the PathView. This ensures PathView gesture grabbing
            // is in sync with other items.
            QPointF pathDelta = pathPoint - startPoint;
            const int startDragDistance = QGuiApplication::styleHints()->startDragDistance();
            if (qAbs(pathDelta.x()) > startDragDistance * 0.8
                    || qAbs(pathDelta.y()) > startDragDistance * 0.8) {
                stealMouse = true;
                q->setKeepMouseGrab(true);
            }
        }
    } else {
        moveReason = QQuickPathViewPrivate::Mouse;
        int count = pathItems == -1 ? modelCount : qMin(pathItems, modelCount);
        qreal diff = (newPc - startPc)*count;
        if (!qFuzzyIsNull(diff)) {
            q->setOffset(offset + diff);
 
            if (diff > modelCount/2)
                diff -= modelCount;
            else if (diff < -modelCount/2)
                diff += modelCount;
 
            qint64 elapsed = currentTimestamp - lastPosTime;
            if (elapsed > 0)
                addVelocitySample(diff / (qreal(elapsed) / 1000));
        }
        if (!moving) {
            moving = true;
            emit q->movingChanged();
            emit q->movementStarted();
        }
        setDragging(true);
    }
    startPc = newPc;
    lastPosTime = currentTimestamp;
}
 
void QQuickPathView::mouseReleaseEvent(QMouseEvent *event)
{
    Q_D(QQuickPathView);
    if (d->interactive) {
        d->handleMouseReleaseEvent(event);
        event->accept();
        ungrabMouse();
    } else {
        QQuickItem::mouseReleaseEvent(event);
    }
}
 
void QQuickPathViewPrivate::handleMouseReleaseEvent(QMouseEvent *event)
{
    Q_Q(QQuickPathView);
    stealMouse = false;
    q->setKeepMouseGrab(false);
    setDragging(false);
    if (!interactive || !timer.isValid() || !model || !modelCount) {
        timer.invalidate();
        if (!tl.isActive())
            q->movementEnding();
        return;
    }
 
    qreal velocity = calcVelocity();
    qint64 elapsed = computeCurrentTime(event) - lastPosTime;
    // Let the velocity linearly decay such that it becomes 0 if elapsed time > QML_FLICK_VELOCITY_DECAY_TIME
    // The intention is that if you are flicking at some speed, then stop in one place for some time before releasing,
    // the previous velocity is lost. (QTBUG-77173, QTBUG-59052)
    velocity *= qreal(qMax(0LL, QML_FLICK_VELOCITY_DECAY_TIME - elapsed)) / QML_FLICK_VELOCITY_DECAY_TIME;
    qCDebug(lcPathView) << "after elapsed time" << elapsed << "velocity decayed to" << velocity;
    qreal count = pathItems == -1 ? modelCount : qMin(pathItems, modelCount);
    const auto averageItemLength = path->path().length() / count;
    qreal pixelVelocity = averageItemLength * velocity;
    if (qAbs(pixelVelocity) > _q_MinimumFlickVelocity) {
        if (qAbs(pixelVelocity) > maximumFlickVelocity || snapMode == QQuickPathView::SnapOneItem) {
            // limit velocity
            qreal maxVel = velocity < 0 ? -maximumFlickVelocity : maximumFlickVelocity;
            velocity = maxVel / averageItemLength;
        }
        // Calculate the distance to be travelled
        qreal v2 = velocity*velocity;
        qreal accel = deceleration/10;
        qreal dist = 0;
        if (haveHighlightRange && (highlightRangeMode == QQuickPathView::StrictlyEnforceRange
                || snapMode != QQuickPathView::NoSnap)) {
            if (snapMode == QQuickPathView::SnapOneItem) {
                // encourage snapping one item in direction of motion
                if (velocity > 0)
                    dist = qRound(0.5 + offset) - offset;
                else
                    dist = qRound(0.5 - offset) + offset;
            } else {
                // + 0.25 to encourage moving at least one item in the flick direction
                dist = qMin(qreal(modelCount-1), qreal(v2 / (accel * 2) + 0.25));
 
                // round to nearest item.
                if (velocity > 0)
                    dist = qRound(dist + offset) - offset;
                else
                    dist = qRound(dist - offset) + offset;
            }
            // Calculate accel required to stop on item boundary
            if (dist <= 0) {
                dist = 0;
                accel = 0;
            } else {
                accel = v2 / (2 * qAbs(dist));
            }
        } else {
            dist = qMin(qreal(modelCount-1), qreal(v2 / (accel * 2)));
        }
        flickDuration = int(1000 * qAbs(velocity) / accel);
        offsetAdj = 0;
        moveOffset.setValue(offset);
        tl.accel(moveOffset, velocity, accel, dist);
        tl.callback(QQuickTimeLineCallback(&moveOffset, fixOffsetCallback, this));
        if (!flicking) {
            flicking = true;
            emit q->flickingChanged();
            emit q->flickStarted();
        }
    } else {
        fixOffset();
    }
 
    timer.invalidate();
    if (!tl.isActive())
        q->movementEnding();
}
 
bool QQuickPathView::childMouseEventFilter(QQuickItem *i, QEvent *e)
{
    Q_D(QQuickPathView);
    if (!isVisible() || !d->interactive || !e->isPointerEvent())
        return QQuickItem::childMouseEventFilter(i, e);
 
    QPointerEvent *pe = static_cast<QPointerEvent *>(e);
    if (QQuickDeliveryAgentPrivate::isMouseEvent(pe)) {
        // The event is localized for the intended receiver (in the delegate, probably),
        // but we need to look at position relative to the PathView itself.
        const auto &point = pe->points().first();
        QPointF localPos = mapFromScene(point.scenePosition());
        QQuickItem *grabber = qmlobject_cast<QQuickItem *>(pe->exclusiveGrabber(point));
        if (grabber == this && d->stealMouse) {
            // we are already the grabber and we do want the mouse event to ourselves.
            return true;
        }
 
        bool grabberDisabled = grabber && !grabber->isEnabled();
        bool stealThisEvent = d->stealMouse;
        if ((stealThisEvent || contains(localPos)) && (!grabber || !grabber->keepMouseGrab() || grabberDisabled)) {
            // Make a localized copy of the QMouseEvent.
            QMutableSinglePointEvent localizedEvent(*static_cast<QMouseEvent *>(pe));
            QMutableEventPoint::setPosition(localizedEvent.point(0), localPos);
            localizedEvent.setAccepted(false);
 
            switch (localizedEvent.type()) {
            case QEvent::MouseMove:
                d->handleMouseMoveEvent(static_cast<QMouseEvent *>(static_cast<QSinglePointEvent *>(&localizedEvent)));
                break;
            case QEvent::MouseButtonPress:
                d->handleMousePressEvent(static_cast<QMouseEvent *>(static_cast<QSinglePointEvent *>(&localizedEvent)));
                stealThisEvent = d->stealMouse;   // Update stealThisEvent in case changed by function call above
                break;
            case QEvent::MouseButtonRelease:
                d->handleMouseReleaseEvent(static_cast<QMouseEvent *>(static_cast<QSinglePointEvent *>(&localizedEvent)));
                break;
            default:
                break;
            }
 
            grabber = qmlobject_cast<QQuickItem *>(localizedEvent.exclusiveGrabber(localizedEvent.points().first()));
            if ((grabber && stealThisEvent && !grabber->keepMouseGrab() && grabber != this) || grabberDisabled)
                pe->setExclusiveGrabber(point, this);
 
            const bool filtered = stealThisEvent || grabberDisabled;
            if (filtered)
                pe->setAccepted(false);
            return filtered;
        } else if (d->timer.isValid()) {
            d->timer.invalidate();
            d->fixOffset();
        }
        if (pe->type() == QEvent::MouseButtonRelease || (grabber && grabber->keepMouseGrab() && !grabberDisabled))
            d->stealMouse = false;
        return false;
    }
 
    return QQuickItem::childMouseEventFilter(i, e);
}
 
void QQuickPathView::mouseUngrabEvent()
{
    Q_D(QQuickPathView);
    if (d->stealMouse ||
            (!d->flicking && d->snapMode != NoSnap && !qFuzzyCompare(qRound(d->offset), d->offset))) {
        // if our mouse grab has been removed (probably by a Flickable),
        // or if we should snap but haven't done it, fix our state
        d->stealMouse = false;
        setKeepMouseGrab(false);
        d->timer.invalidate();
        d->fixOffset();
        d->setDragging(false);
        if (!d->tl.isActive())
            movementEnding();
    }
}
 
void QQuickPathView::updatePolish()
{
    QQuickItem::updatePolish();
    refill();
}
 
static inline int currentIndexRemainder(int currentIndex, int modelCount) noexcept
{
    if (currentIndex < 0)
        return modelCount + currentIndex % modelCount;
    else
        return currentIndex % modelCount;
}
 
void QQuickPathView::componentComplete()
{
    Q_D(QQuickPathView);
    if (d->model && d->ownModel)
        static_cast<QQmlDelegateModel *>(d->model.data())->componentComplete();
 
    QQuickItem::componentComplete();
 
    if (d->model) {
        d->modelCount = d->model->count();
        if (d->modelCount && d->currentIndex != 0) // an initial value has been provided for currentIndex
            d->offset = std::fmod(qreal(d->modelCount - currentIndexRemainder(d->currentIndex, d->modelCount)), qreal(d->modelCount));
    }
 
    d->createHighlight();
    d->regenerate();
    d->updateHighlight();
    d->updateCurrent();
 
    if (d->modelCount)
        emit countChanged();
}
 
void QQuickPathView::refill()
{
    Q_D(QQuickPathView);
 
    if (d->inRefill) {
        d->scheduleLayout();
        return;
    }
 
    d->layoutScheduled = false;
 
    if (!d->isValid() || !isComponentComplete())
        return;
 
    d->inRefill = true;
 
    bool currentVisible = false;
    int count = d->pathItems == -1 ? d->modelCount : qMin(d->pathItems, d->modelCount);
 
    // first move existing items and remove items off path
    qCDebug(lcItemViewDelegateLifecycle) << "currentIndex" << d->currentIndex << "offset" << d->offset;
    QList<QQuickItem*>::iterator it = d->items.begin();
    while (it != d->items.end()) {
        QQuickItem *item = *it;
        int idx = d->model->indexOf(item, nullptr);
        qreal pos = d->positionOfIndex(idx);
        if (lcItemViewDelegateLifecycle().isDebugEnabled()) {
            QQuickText *text = qmlobject_cast<QQuickText*>(item);
            if (text)
                qCDebug(lcItemViewDelegateLifecycle) << "idx" << idx << "@" << pos << ": QQuickText" << text->objectName() << QStringView{text->text()}.left(40);
            else
                qCDebug(lcItemViewDelegateLifecycle) << "idx" << idx << "@" << pos << ":" << item;
        }
        if (pos < 1) {
            d->updateItem(item, pos);
            if (idx == d->currentIndex) {
                currentVisible = true;
                d->currentItemOffset = pos;
            }
            ++it;
        } else {
            d->updateItem(item, pos);
            if (QQuickPathViewAttached *att = d->attached(item))
                att->setOnPath(pos < 1);
            if (!d->isInBound(pos, d->mappedRange - d->mappedCache, 1 + d->mappedCache)) {
                qCDebug(lcItemViewDelegateLifecycle) << "release" << idx << "@" << pos << ", !isInBound: lower" << (d->mappedRange - d->mappedCache) << "upper" << (1 + d->mappedCache);
                d->releaseItem(item);
                it = d->items.erase(it);
            } else {
                ++it;
            }
        }
    }
 
    bool waiting = false;
    if (d->modelCount) {
        // add items as needed
        if (d->items.size() < count+d->cacheSize) {
            int endIdx = 0;
            qreal endPos;
            int startIdx = 0;
            qreal startPos = 0;
            const bool wasEmpty = d->items.isEmpty();
            if (!wasEmpty) {
                //Find the beginning and end, items may not be in sorted order
                endPos = -1;
                startPos = 2;
 
                for (QQuickItem * item : std::as_const(d->items)) {
                    int idx = d->model->indexOf(item, nullptr);
                    qreal curPos = d->positionOfIndex(idx);
                    if (curPos > endPos) {
                        endPos = curPos;
                        endIdx = idx;
                    }
 
                    if (curPos < startPos) {
                        startPos = curPos;
                        startIdx = idx;
                    }
                }
            } else {
                if (d->haveHighlightRange
                            && (d->highlightRangeMode != QQuickPathView::NoHighlightRange
                                    || d->snapMode != QQuickPathView::NoSnap))
                    startPos = d->highlightRangeStart;
                // With no items, then "end" is just off the top so we populate via append
                endIdx = (qRound(d->modelCount - d->offset) - 1) % d->modelCount;
                endPos = d->positionOfIndex(endIdx);
            }
            //Append
            int idx = endIdx + 1;
            if (idx >= d->modelCount)
                idx = 0;
            qreal nextPos = d->positionOfIndex(idx);
            while ((d->isInBound(nextPos, endPos, 1 + d->mappedCache) || !d->items.size())
                    && d->items.size() < count+d->cacheSize) {
                qCDebug(lcItemViewDelegateLifecycle) << "append" << idx << "@" << nextPos << (d->currentIndex == idx ? "current" : "") << "items count was" << d->items.size();
                QQuickItem *item = d->getItem(idx, idx+1, nextPos >= 1);
                if (!item) {
                    waiting = true;
                    break;
                }
                if (d->items.contains(item)) {
                    d->releaseItem(item);
                    break; //Otherwise we'd "re-add" it, and get confused
                }
                if (d->currentIndex == idx) {
                    currentVisible = true;
                    d->currentItemOffset = nextPos;
                }
                d->items.append(item);
                d->updateItem(item, nextPos);
                endIdx = idx;
                endPos = nextPos;
                ++idx;
                if (idx >= d->modelCount)
                    idx = 0;
                nextPos = d->positionOfIndex(idx);
            }
 
            //Prepend
            idx = (wasEmpty ? d->calcCurrentIndex() : startIdx) - 1;
 
            if (idx < 0)
                idx = d->modelCount - 1;
            nextPos = d->positionOfIndex(idx);
            while (!waiting && d->isInBound(nextPos, d->mappedRange - d->mappedCache, startPos)
                    && d->items.size() < count+d->cacheSize) {
                qCDebug(lcItemViewDelegateLifecycle) << "prepend" << idx << "@" << nextPos << (d->currentIndex == idx ? "current" : "") << "items count was" << d->items.size();
                QQuickItem *item = d->getItem(idx, idx+1, nextPos >= 1);
                if (!item) {
                    waiting = true;
                    break;
                }
                if (d->items.contains(item)) {
                    d->releaseItem(item);
                    break; //Otherwise we'd "re-add" it, and get confused
                }
                if (d->currentIndex == idx) {
                    currentVisible = true;
                    d->currentItemOffset = nextPos;
                }
                d->items.prepend(item);
                d->updateItem(item, nextPos);
                startIdx = idx;
                startPos = nextPos;
                --idx;
                if (idx < 0)
                    idx = d->modelCount - 1;
                nextPos = d->positionOfIndex(idx);
            }
 
            // In rare cases, when jumping around with pathCount close to modelCount,
            // new items appear in the middle. This more generic addition iteration handles this
            // Since this is the rare case, we try append/prepend first and only do this if
            // there are gaps still left to fill.
            if (!waiting && d->items.size() < count+d->cacheSize) {
                qCDebug(lcItemViewDelegateLifecycle) << "Checking for pathview middle inserts, items count was" << d->items.size();
                idx = startIdx;
                QQuickItem *lastItem = d->items.at(0);
                while (idx != endIdx) {
                    nextPos = d->positionOfIndex(idx);
                    if (d->isInBound(nextPos, d->mappedRange - d->mappedCache, 1 + d->mappedCache)) {
                        //This gets the reference from the delegate model, and will not re-create
                        QQuickItem *item = d->getItem(idx, idx+1, nextPos >= 1);
                        if (!item) {
                            waiting = true;
                            break;
                        }
 
                        if (!d->items.contains(item)) { //We found a hole
                            qCDebug(lcItemViewDelegateLifecycle) << "middle insert" << idx << "@" << nextPos
                                                                 << (d->currentIndex == idx ? "current" : "")
                                                                 << "items count was" << d->items.size();
                            if (d->currentIndex == idx) {
                                currentVisible = true;
                                d->currentItemOffset = nextPos;
                            }
                            int lastListIdx = d->items.indexOf(lastItem);
                            d->items.insert(lastListIdx + 1, item);
                            d->updateItem(item, nextPos);
                        } else {
                            d->releaseItem(item);
                        }
 
                        lastItem = item;
                    }
 
                    ++idx;
                    if (idx >= d->modelCount)
                        idx = 0;
                }
            }
        }
    }
 
    bool currentChanged = false;
    if (!currentVisible) {
        d->currentItemOffset = 1;
        if (d->currentItem) {
            d->updateItem(d->currentItem, 1);
        } else if (!waiting && d->currentIndex >= 0 && d->currentIndex < d->modelCount) {
            if ((d->currentItem = d->getItem(d->currentIndex, d->currentIndex))) {
                currentChanged = true;
                d->updateItem(d->currentItem, 1);
                if (QQuickPathViewAttached *att = d->attached(d->currentItem))
                    att->setIsCurrentItem(true);
            }
        }
    } else if (!waiting && !d->currentItem) {
        if ((d->currentItem = d->getItem(d->currentIndex, d->currentIndex))) {
            currentChanged = true;
            d->currentItem->setFocus(true);
            if (QQuickPathViewAttached *att = d->attached(d->currentItem))
                att->setIsCurrentItem(true);
        }
    }
 
    if (d->highlightItem && d->haveHighlightRange && d->highlightRangeMode == QQuickPathView::StrictlyEnforceRange) {
        d->updateItem(d->highlightItem, d->highlightRangeStart);
        if (QQuickPathViewAttached *att = d->attached(d->highlightItem))
            att->setOnPath(true);
    } else if (d->highlightItem && d->moveReason != QQuickPathViewPrivate::SetIndex) {
        d->updateItem(d->highlightItem, d->currentItemOffset);
        if (QQuickPathViewAttached *att = d->attached(d->highlightItem))
            att->setOnPath(currentVisible);
    }
    for (QQuickItem *item : std::as_const(d->itemCache))
        d->releaseItem(item);
    d->itemCache.clear();
 
    d->inRefill = false;
    if (currentChanged)
        emit currentItemChanged();
}
 
void QQuickPathView::modelUpdated(const QQmlChangeSet &changeSet, bool reset)
{
    Q_D(QQuickPathView);
    if (!d->model || !d->model->isValid() || !d->path || !isComponentComplete())
        return;
 
    if (reset) {
        d->modelCount = d->model->count();
        d->regenerate();
        emit countChanged();
        return;
    }
 
    if (changeSet.removes().isEmpty() && changeSet.inserts().isEmpty())
        return;
 
    const int modelCount = d->modelCount;
    int moveId = -1;
    int moveOffset = 0;
    bool currentChanged = false;
    bool changedOffset = false;
    for (const QQmlChangeSet::Change &r : changeSet.removes()) {
        if (moveId == -1 && d->currentIndex >= r.index + r.count) {
            d->currentIndex -= r.count;
            currentChanged = true;
        } else if (moveId == -1 && d->currentIndex >= r.index && d->currentIndex < r.index + r.count) {
            // current item has been removed.
            if (r.isMove()) {
                moveId = r.moveId;
                moveOffset = d->currentIndex - r.index;
            } else if (d->currentItem) {
                if (QQuickPathViewAttached *att = d->attached(d->currentItem))
                    att->setIsCurrentItem(true);
                d->releaseItem(d->currentItem);
                d->currentItem = nullptr;
            }
            d->currentIndex = qMin(r.index, d->modelCount - r.count - 1);
            currentChanged = true;
        }
 
        if (r.index > d->currentIndex) {
            changedOffset = true;
            d->offset -= r.count;
            d->offsetAdj -= r.count;
        }
        d->modelCount -= r.count;
    }
    for (const QQmlChangeSet::Change &i : changeSet.inserts()) {
        if (d->modelCount) {
            if (moveId == -1 && i.index <= d->currentIndex) {
                d->currentIndex += i.count;
                currentChanged = true;
            } else {
                if (moveId != -1 && moveId == i.moveId) {
                    d->currentIndex = i.index + moveOffset;
                    currentChanged = true;
                }
                if (i.index > d->currentIndex) {
                    d->offset += i.count;
                    d->offsetAdj += i.count;
                    changedOffset = true;
                }
            }
        }
        d->modelCount += i.count;
    }
 
    d->offset = std::fmod(d->offset, qreal(d->modelCount));
    if (d->offset < 0)
        d->offset += d->modelCount;
    if (d->currentIndex == -1)
        d->currentIndex = d->calcCurrentIndex();
 
    d->itemCache += d->items;
    d->items.clear();
 
    if (!d->modelCount) {
        for (QQuickItem * item : std::as_const(d->itemCache))
            d->releaseItem(item);
        d->itemCache.clear();
        d->offset = 0;
        changedOffset = true;
        d->tl.reset(d->moveOffset);
    } else {
        if (!d->flicking && !d->moving && d->haveHighlightRange && d->highlightRangeMode == QQuickPathView::StrictlyEnforceRange) {
            d->offset = std::fmod(qreal(d->modelCount - d->currentIndex), qreal(d->modelCount));
            changedOffset = true;
        }
        d->updateMappedRange();
        d->scheduleLayout();
    }
    if (changedOffset)
        emit offsetChanged();
    if (currentChanged)
        emit currentIndexChanged();
    if (d->modelCount != modelCount)
        emit countChanged();
}
 
void QQuickPathView::destroyingItem(QObject *item)
{
    Q_UNUSED(item);
}
 
void QQuickPathView::ticked()
{
    Q_D(QQuickPathView);
    d->updateCurrent();
}
 
void QQuickPathView::movementEnding()
{
    Q_D(QQuickPathView);
    if (d->flicking) {
        d->flicking = false;
        emit flickingChanged();
        emit flickEnded();
    }
    if (d->moving && !d->stealMouse) {
        d->moving = false;
        emit movingChanged();
        emit movementEnded();
    }
    d->moveDirection = d->movementDirection;
}
 
// find the item closest to the snap position
int QQuickPathViewPrivate::calcCurrentIndex()
{
    int current = 0;
    if (modelCount && model && items.size()) {
        offset = std::fmod(offset, qreal(modelCount));
        if (offset < 0)
            offset += modelCount;
        current = qRound(qAbs(std::fmod(modelCount - offset, qreal(modelCount))));
        current = current % modelCount;
    }
 
    return current;
}
 
void QQuickPathViewPrivate::createCurrentItem()
{
    if (requestedIndex != -1)
        return;
 
    bool inItems = false;
    for (QQuickItem *item : std::as_const(items)) {
        if (model->indexOf(item, nullptr) == currentIndex) {
            inItems = true;
            break;
        }
    }
 
    if (inItems) {
        if ((currentItem = getItem(currentIndex, currentIndex))) {
            currentItem->setFocus(true);
            if (QQuickPathViewAttached *att = attached(currentItem))
                att->setIsCurrentItem(true);
        }
    } else if (currentIndex >= 0 && currentIndex < modelCount) {
        if ((currentItem = getItem(currentIndex, currentIndex))) {
            updateItem(currentItem, 1);
            if (QQuickPathViewAttached *att = attached(currentItem))
                att->setIsCurrentItem(true);
        }
    }
}
 
void QQuickPathViewPrivate::updateCurrent()
{
    Q_Q(QQuickPathView);
    if (moveReason == SetIndex)
        return;
    if (!modelCount || !haveHighlightRange || highlightRangeMode != QQuickPathView::StrictlyEnforceRange)
        return;
 
    int idx = calcCurrentIndex();
    if (model && (idx != currentIndex || !currentItem)) {
        if (currentItem) {
            if (QQuickPathViewAttached *att = attached(currentItem))
                att->setIsCurrentItem(false);
            releaseItem(currentItem);
        }
        int oldCurrentIndex = currentIndex;
        currentIndex = idx;
        currentItem = nullptr;
        createCurrentItem();
        if (oldCurrentIndex != currentIndex)
            emit q->currentIndexChanged();
        emit q->currentItemChanged();
    }
}
 
void QQuickPathViewPrivate::fixOffsetCallback(void *d)
{
    static_cast<QQuickPathViewPrivate *>(d)->fixOffset();
}
 
void QQuickPathViewPrivate::fixOffset()
{
    Q_Q(QQuickPathView);
    if (model && items.size()) {
        if (haveHighlightRange && (highlightRangeMode == QQuickPathView::StrictlyEnforceRange
                || snapMode != QQuickPathView::NoSnap)) {
            int curr = calcCurrentIndex();
            if (curr != currentIndex && highlightRangeMode == QQuickPathView::StrictlyEnforceRange)
                q->setCurrentIndex(curr);
            else
                snapToIndex(curr, Other);
        }
    }
}
 
void QQuickPathViewPrivate::snapToIndex(int index, MovementReason reason)
{
    if (!model || modelCount <= 0)
        return;
 
    qreal targetOffset = std::fmod(qreal(modelCount - index), qreal(modelCount));
    moveReason = reason;
    offsetAdj = 0;
    tl.reset(moveOffset);
    moveOffset.setValue(offset);
 
    const int duration = highlightMoveDuration;
 
    const qreal count = pathItems == -1 ? modelCount : qMin(pathItems, modelCount);
    const qreal averageItemLength = path->path().length() / count;
    const qreal threshold = 0.5 / averageItemLength; // if we are within .5 px, we want to immediately assign rather than animate
 
    if (!duration || qAbs(offset - targetOffset) < threshold || (qFuzzyIsNull(targetOffset) && qAbs(modelCount - offset) < threshold)) {
        tl.set(moveOffset, targetOffset);
    } else if (moveDirection == QQuickPathView::Positive || (moveDirection == QQuickPathView::Shortest && targetOffset - offset > modelCount/2)) {
        qreal distance = modelCount - targetOffset + offset;
        if (targetOffset > moveOffset) {
            tl.move(moveOffset, 0, QEasingCurve(QEasingCurve::InQuad), int(duration * offset / distance));
            tl.set(moveOffset, modelCount);
            tl.move(moveOffset, targetOffset, QEasingCurve(qFuzzyIsNull(offset) ? QEasingCurve::InOutQuad : QEasingCurve::OutQuad), int(duration * (modelCount-targetOffset) / distance));
        } else {
            tl.move(moveOffset, targetOffset, QEasingCurve(QEasingCurve::InOutQuad), duration);
        }
    } else if (moveDirection == QQuickPathView::Negative || targetOffset - offset <= -modelCount/2) {
        qreal distance = modelCount - offset + targetOffset;
        if (targetOffset < moveOffset) {
            tl.move(moveOffset, modelCount, QEasingCurve(qFuzzyIsNull(targetOffset) ? QEasingCurve::InOutQuad : QEasingCurve::InQuad), int(duration * (modelCount-offset) / distance));
            tl.set(moveOffset, 0);
            tl.move(moveOffset, targetOffset, QEasingCurve(QEasingCurve::OutQuad), int(duration * targetOffset / distance));
        } else {
            tl.move(moveOffset, targetOffset, QEasingCurve(QEasingCurve::InOutQuad), duration);
        }
    } else {
        tl.move(moveOffset, targetOffset, QEasingCurve(QEasingCurve::InOutQuad), duration);
    }
}
 
QQuickPathViewAttached *QQuickPathView::qmlAttachedProperties(QObject *obj)
{
    return new QQuickPathViewAttached(obj);
}
 
QT_END_NAMESPACE
 
#include "moc_qquickpathview_p.cpp"