qquickitemviewtransition.cpp

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// Copyright (C) 2016 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 "qquickitemviewtransition_p.h"
#include <QtQuick/qquickitem.h>
#include <QtQuick/private/qquicktransition_p.h>
#include <QtQuick/private/qquicktransitionmanager_p_p.h>
 
QT_BEGIN_NAMESPACE
 
static QList<int> qquickitemviewtransition_emptyIndexes = QList<int>();
static QList<QObject *> qquickitemviewtransition_emptyTargets = QList<QObject *>();
 
 
class QQuickItemViewTransitionJob : public QQuickTransitionManager
{
public:
    QQuickItemViewTransitionJob();
    ~QQuickItemViewTransitionJob();
 
    void startTransition(QQuickItemViewTransitionableItem *item, int index, QQuickItemViewTransitioner *transitioner, QQuickItemViewTransitioner::TransitionType type, const QPointF &to, bool isTargetItem);
 
    QQuickItemViewTransitioner *m_transitioner;
    QQuickItemViewTransitionableItem *m_item;
    QPointF m_toPos;
    QQuickItemViewTransitioner::TransitionType m_type;
    bool m_isTarget;
 
protected:
    void finished() override;
};
 
 
QQuickItemViewTransitionJob::QQuickItemViewTransitionJob()
    : m_transitioner(nullptr)
    , m_item(nullptr)
    , m_type(QQuickItemViewTransitioner::NoTransition)
    , m_isTarget(false)
{
}
 
QQuickItemViewTransitionJob::~QQuickItemViewTransitionJob()
{
    if (m_transitioner)
        m_transitioner->runningJobs.remove(this);
}
 
void QQuickItemViewTransitionJob::startTransition(QQuickItemViewTransitionableItem *item, int index, QQuickItemViewTransitioner *transitioner, QQuickItemViewTransitioner::TransitionType type, const QPointF &to, bool isTargetItem)
{
    if (type == QQuickItemViewTransitioner::NoTransition)
        return;
    if (!item) {
        qWarning("startTransition(): invalid item");
        return;
    }
    if (!transitioner) {
        qWarning("startTransition(): invalid transitioner");
        return;
    }
 
    QQuickTransition *trans = transitioner->transitionObject(type, isTargetItem);
    if (!trans) {
        qWarning("QQuickItemView: invalid view transition!");
        return;
    }
 
    m_item = item;
    m_transitioner = transitioner;
    m_toPos = to;
    m_type = type;
    m_isTarget = isTargetItem;
 
    QQuickViewTransitionAttached *attached =
            static_cast<QQuickViewTransitionAttached*>(qmlAttachedPropertiesObject<QQuickViewTransitionAttached>(trans));
    if (attached) {
        attached->m_index = index;
        attached->m_item = item->item;
        attached->m_destination = to;
        attached->m_targetIndexes = m_transitioner->targetIndexes(type);
        attached->m_targetItems = m_transitioner->targetItems(type);
        emit attached->indexChanged();
        emit attached->itemChanged();
        emit attached->destinationChanged();
        emit attached->targetIndexesChanged();
        emit attached->targetItemsChanged();
    }
 
    QQuickStateOperation::ActionList actions;
    actions << QQuickStateAction(item->item, QLatin1String("x"), QVariant(to.x()));
    actions << QQuickStateAction(item->item, QLatin1String("y"), QVariant(to.y()));
 
    actions[0].fromValue = item->itemX();
    actions[1].fromValue = item->itemY();
    m_transitioner->runningJobs << this;
    QQuickTransitionManager::transition(actions, trans, item->item);
}
 
void QQuickItemViewTransitionJob::finished()
{
    QQuickTransitionManager::finished();
 
    if (m_transitioner) {
        RETURN_IF_DELETED(m_transitioner->finishedTransition(this, m_item));
        m_transitioner = nullptr;
    }
 
    m_item = nullptr;
    m_toPos.setX(0);
    m_toPos.setY(0);
    m_type = QQuickItemViewTransitioner::NoTransition;
    m_isTarget = false;
}
 
 
QQuickItemViewTransitioner::QQuickItemViewTransitioner()
    : populateTransition(nullptr)
    , addTransition(nullptr), addDisplacedTransition(nullptr)
    , moveTransition(nullptr), moveDisplacedTransition(nullptr)
    , removeTransition(nullptr), removeDisplacedTransition(nullptr)
    , displacedTransition(nullptr)
    , changeListener(nullptr)
    , usePopulateTransition(false)
{
}
 
QQuickItemViewTransitioner::~QQuickItemViewTransitioner()
{
    typedef QSet<QQuickItemViewTransitionJob *>::iterator JobIt;
 
    for (JobIt it = runningJobs.begin(), end = runningJobs.end(); it != end; ++it)
        (*it)->m_transitioner = nullptr;
}
 
bool QQuickItemViewTransitioner::canTransition(QQuickItemViewTransitioner::TransitionType type, bool asTarget) const
{
    if (!asTarget
            && type != NoTransition && type != PopulateTransition
            && displacedTransition && displacedTransition->enabled()) {
        return true;
    }
 
    switch (type) {
    case NoTransition:
        break;
    case PopulateTransition:
        return usePopulateTransition
                && populateTransition && populateTransition->enabled();
    case AddTransition:
        if (asTarget)
            return addTransition && addTransition->enabled();
        else
            return addDisplacedTransition && addDisplacedTransition->enabled();
    case MoveTransition:
        if (asTarget)
            return moveTransition && moveTransition->enabled();
        else
            return moveDisplacedTransition && moveDisplacedTransition->enabled();
    case RemoveTransition:
        if (asTarget)
            return removeTransition && removeTransition->enabled();
        else
            return removeDisplacedTransition && removeDisplacedTransition->enabled();
    }
    return false;
}
 
void QQuickItemViewTransitioner::transitionNextReposition(QQuickItemViewTransitionableItem *item, QQuickItemViewTransitioner::TransitionType type, bool isTarget)
{
    item->setNextTransition(type, isTarget);
}
 
void QQuickItemViewTransitioner::addToTargetLists(QQuickItemViewTransitioner::TransitionType type, QQuickItemViewTransitionableItem *item, int index)
{
    switch (type) {
    case NoTransition:
        break;
    case PopulateTransition:
    case AddTransition:
        addTransitionIndexes << index;
        addTransitionTargets << item->item;
        break;
    case MoveTransition:
        moveTransitionIndexes << index;
        moveTransitionTargets << item->item;
        break;
    case RemoveTransition:
        removeTransitionIndexes << index;
        removeTransitionTargets << item->item;
        break;
    }
}
 
void QQuickItemViewTransitioner::resetTargetLists()
{
    addTransitionIndexes.clear();
    addTransitionTargets.clear();
 
    removeTransitionIndexes.clear();
    removeTransitionTargets.clear();
 
    moveTransitionIndexes.clear();
    moveTransitionTargets.clear();
}
 
QQuickTransition *QQuickItemViewTransitioner::transitionObject(QQuickItemViewTransitioner::TransitionType type, bool asTarget) const
{
    if (type == QQuickItemViewTransitioner::NoTransition)
        return nullptr;
 
    if (type == PopulateTransition)
        asTarget = true;    // no separate displaced transition
 
    QQuickTransition *trans = nullptr;
    switch (type) {
    case NoTransition:
        break;
    case PopulateTransition:
        trans = populateTransition;
        break;
    case AddTransition:
        trans = asTarget ? addTransition : addDisplacedTransition;
        break;
    case MoveTransition:
        trans = asTarget ? moveTransition : moveDisplacedTransition;
        break;
    case RemoveTransition:
        trans = asTarget ? removeTransition : removeDisplacedTransition;
        break;
    }
 
    if (!asTarget && (!trans || !trans->enabled()))
        trans = displacedTransition;
    if (trans && trans->enabled())
        return trans;
    return nullptr;
}
 
const QList<int> &QQuickItemViewTransitioner::targetIndexes(QQuickItemViewTransitioner::TransitionType type) const
{
    switch (type) {
    case NoTransition:
        break;
    case PopulateTransition:
    case AddTransition:
        return addTransitionIndexes;
    case MoveTransition:
        return moveTransitionIndexes;
    case RemoveTransition:
        return removeTransitionIndexes;
    }
 
    return qquickitemviewtransition_emptyIndexes;
}
 
const QList<QObject *> &QQuickItemViewTransitioner::targetItems(QQuickItemViewTransitioner::TransitionType type) const
{
    switch (type) {
    case NoTransition:
        break;
    case PopulateTransition:
    case AddTransition:
        return addTransitionTargets;
    case MoveTransition:
        return moveTransitionTargets;
    case RemoveTransition:
        return removeTransitionTargets;
    }
 
    return qquickitemviewtransition_emptyTargets;
}
 
void QQuickItemViewTransitioner::finishedTransition(QQuickItemViewTransitionJob *job, QQuickItemViewTransitionableItem *item)
{
    if (!runningJobs.contains(job))
        return;
    runningJobs.remove(job);
    if (item) {
        item->finishedTransition();
        if (changeListener)
            changeListener->viewItemTransitionFinished(item);
    }
}
 
 
QQuickItemViewTransitionableItem::QQuickItemViewTransitionableItem(QQuickItem *i)
    : item(i)
    , transition(nullptr)
    , nextTransitionType(QQuickItemViewTransitioner::NoTransition)
    , isTransitionTarget(false)
    , nextTransitionToSet(false)
    , nextTransitionFromSet(false)
    , lastMovedToSet(false)
    , prepared(false)
{
}
 
QQuickItemViewTransitionableItem::~QQuickItemViewTransitionableItem()
{
    delete transition;
}
 
qreal QQuickItemViewTransitionableItem::itemX() const
{
    if (nextTransitionType != QQuickItemViewTransitioner::NoTransition)
        return nextTransitionToSet ? nextTransitionTo.x() : item->x();
    else if (transition && transition->isRunning())
        return transition->m_toPos.x();
    else
        return item->x();
}
 
qreal QQuickItemViewTransitionableItem::itemY() const
{
    // If item is transitioning to some pos, return that dest pos.
    // If item was redirected to some new pos before the current transition finished,
    // return that new pos.
    if (nextTransitionType != QQuickItemViewTransitioner::NoTransition)
        return nextTransitionToSet ? nextTransitionTo.y() : item->y();
    else if (transition && transition->isRunning())
        return transition->m_toPos.y();
    else
        return item->y();
}
 
void QQuickItemViewTransitionableItem::moveTo(const QPointF &pos, bool immediate)
{
    if (!nextTransitionFromSet && nextTransitionType != QQuickItemViewTransitioner::NoTransition) {
        nextTransitionFrom = item->position();
        nextTransitionFromSet = true;
    }
 
    lastMovedTo = pos;
    lastMovedToSet = true;
 
    if (immediate || !transitionScheduledOrRunning()) {
        if (immediate)
            stopTransition();
        item->setPosition(pos);
    } else {
        nextTransitionTo = pos;
        nextTransitionToSet = true;
    }
}
 
bool QQuickItemViewTransitionableItem::transitionScheduledOrRunning() const
{
    return (transition && transition->isRunning())
            || nextTransitionType != QQuickItemViewTransitioner::NoTransition;
}
 
bool QQuickItemViewTransitionableItem::transitionRunning() const
{
    return (transition && transition->isRunning());
}
 
bool QQuickItemViewTransitionableItem::isPendingRemoval() const
{
    if (nextTransitionType == QQuickItemViewTransitioner::RemoveTransition)
        return isTransitionTarget;
    if (transition && transition->isRunning() && transition->m_type == QQuickItemViewTransitioner::RemoveTransition)
        return transition->m_isTarget;
    return false;
}
 
bool QQuickItemViewTransitionableItem::prepareTransition(QQuickItemViewTransitioner *transitioner, int index, const QRectF &viewBounds)
{
    if (nextTransitionType == QQuickItemViewTransitioner::NoTransition)
        return false;
 
    if (isTransitionTarget) {
        // If item is not already moving somewhere, set it to not move anywhere.
        // This ensures that removed targets don't transition to the default (0,0) and that
        // items set for other transition types only transition if they actually move somewhere.
        if (!nextTransitionToSet)
            moveTo(item->position());
    } else {
        // don't start displaced transitions that don't move anywhere
        if (!nextTransitionToSet || (nextTransitionFromSet && nextTransitionFrom == nextTransitionTo)) {
            clearCurrentScheduledTransition();
            return false;
        }
    }
 
    bool doTransition = false;
 
    // For move transitions (both target and displaced) and displaced transitions of other
    // types, only run the transition if the item is actually moving to another position.
    switch (nextTransitionType) {
    case QQuickItemViewTransitioner::NoTransition:
    {
        return false;
    }
    case QQuickItemViewTransitioner::PopulateTransition:
    {
        doTransition = viewBounds.intersects(QRectF(nextTransitionTo.x(), nextTransitionTo.y(), item->width(), item->height()));
        break;
    }
    case QQuickItemViewTransitioner::AddTransition:
    case QQuickItemViewTransitioner::RemoveTransition:
        if (viewBounds.isNull()) {
            if (isTransitionTarget)
                doTransition = true;
            else
                doTransition = transitionWillChangePosition();
        } else if (isTransitionTarget) {
            // For Add targets, do transition if item is moving into visible area
            // For Remove targets, do transition if item is currently in visible area
            doTransition = (nextTransitionType == QQuickItemViewTransitioner::AddTransition)
                    ? viewBounds.intersects(QRectF(nextTransitionTo.x(), nextTransitionTo.y(), item->width(), item->height()))
                    : viewBounds.intersects(QRectF(item->x(), item->y(), item->width(), item->height()));
        } else {
            // do transition if moving from or into visible area
            if (viewBounds.intersects(QRectF(item->x(), item->y(), item->width(), item->height()))
                    || viewBounds.intersects(QRectF(nextTransitionTo.x(), nextTransitionTo.y(), item->width(), item->height()))) {
                doTransition = transitionWillChangePosition();
            }
        }
        break;
    case QQuickItemViewTransitioner::MoveTransition:
        // do transition if moving from or into visible area
        if (transitionWillChangePosition()) {
            doTransition = viewBounds.isNull()
                    || viewBounds.intersects(QRectF(item->x(), item->y(), item->width(), item->height()))
                    || viewBounds.intersects(QRectF(nextTransitionTo.x(), nextTransitionTo.y(), item->width(), item->height()));
        }
        break;
    }
 
    if (doTransition) {
        // add item to target lists even if canTransition() is false for a target transition,
        // since the target lists still need to be filled for displaced transitions
        if (isTransitionTarget)
            transitioner->addToTargetLists(nextTransitionType, this, index);
        doTransition = transitioner->canTransition(nextTransitionType, isTransitionTarget);
    }
 
    if (!doTransition) {
        // if transition type is not valid, the previous transition still has to be
        // canceled so that the item can move immediately to the right position
        item->setPosition(nextTransitionTo);
        ACTION_IF_DELETED(this, stopTransition(), return false);
    }
 
    prepared = true;
    return doTransition;
}
 
void QQuickItemViewTransitionableItem::startTransition(QQuickItemViewTransitioner *transitioner, int index)
{
    if (nextTransitionType == QQuickItemViewTransitioner::NoTransition)
        return;
 
    if (!prepared) {
        qWarning("QQuickViewItem::prepareTransition() not called!");
        return;
    }
 
    if (!transition || transition->m_type != nextTransitionType || transition->m_isTarget != isTransitionTarget) {
        if (transition)
            RETURN_IF_DELETED(transition->cancel());
        delete transition;
        transition = new QQuickItemViewTransitionJob;
    }
 
    RETURN_IF_DELETED(transition->startTransition(this, index, transitioner, nextTransitionType, nextTransitionTo, isTransitionTarget));
    clearCurrentScheduledTransition();
}
 
void QQuickItemViewTransitionableItem::completeTransition(QQuickTransition *quickTransition)
{
    if (nextTransitionType == QQuickItemViewTransitioner::NoTransition)
        return;
 
    if (!prepared) {
        qWarning("QQuickViewItem::prepareTransition() not called!");
        return;
    }
 
    if (!item) {
        qWarning("No target for transition!");
        return;
    }
 
    if (!transition || transition->m_type != nextTransitionType || transition->m_isTarget != isTransitionTarget) {
        if (transition)
            RETURN_IF_DELETED(transition->cancel());
        delete transition;
        transition = new QQuickItemViewTransitionJob;
    }
 
    QQuickStateOperation::ActionList actions; // not used
    QList<QQmlProperty> after; // not used
    QScopedPointer<QQuickTransitionInstance> instance(
                quickTransition->prepare(actions, after, transition, item));
    RETURN_IF_DELETED(instance->complete());
 
    clearCurrentScheduledTransition();
}
 
void QQuickItemViewTransitionableItem::setNextTransition(QQuickItemViewTransitioner::TransitionType type, bool isTargetItem)
{
    // Don't reset nextTransitionToSet - once it is set, it cannot be changed
    // until the animation finishes since the itemX() and itemY() may be used
    // to calculate positions for transitions for other items in the view.
    nextTransitionType = type;
    isTransitionTarget = isTargetItem;
 
    if (!nextTransitionFromSet && lastMovedToSet) {
        nextTransitionFrom = lastMovedTo;
        nextTransitionFromSet = true;
    }
}
 
bool QQuickItemViewTransitionableItem::transitionWillChangePosition() const
{
    if (transitionRunning() && transition->m_toPos != nextTransitionTo)
        return true;
    if (!nextTransitionFromSet)
        return false;
    return nextTransitionTo != nextTransitionFrom;
}
 
void QQuickItemViewTransitionableItem::resetNextTransitionPos()
{
    nextTransitionToSet = false;
    nextTransitionTo = QPointF();
}
 
void QQuickItemViewTransitionableItem::finishedTransition()
{
    resetNextTransitionPos();
}
 
void QQuickItemViewTransitionableItem::clearCurrentScheduledTransition()
{
    // Just clear the current scheduled transition - don't touch the nextTransitionTo
    // which may have already been set for a previously scheduled transition
 
    nextTransitionType = QQuickItemViewTransitioner::NoTransition;
    isTransitionTarget = false;
    prepared = false;
    nextTransitionFromSet = false;
}
 
void QQuickItemViewTransitionableItem::stopTransition()
{
    if (transition)
        RETURN_IF_DELETED(transition->cancel());
    delete transition;
    transition = nullptr;
    clearCurrentScheduledTransition();
    resetNextTransitionPos();
}
 
 
QQuickViewTransitionAttached::QQuickViewTransitionAttached(QObject *parent)
    : QObject(parent), m_index(-1)
{
}
QQmlListProperty<QObject> QQuickViewTransitionAttached::targetItems()
{
    return QQmlListProperty<QObject>(this, &m_targetItems);
}
 
QQuickViewTransitionAttached *QQuickViewTransitionAttached::qmlAttachedProperties(QObject *obj)
{
    return new QQuickViewTransitionAttached(obj);
}
 
QT_END_NAMESPACE
 
#include "moc_qquickitemviewtransition_p.cpp"