qquickswipedelegate.cpp

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// Copyright (C) 2017 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 "qquickswipedelegate_p.h"
#include "qquickswipedelegate_p_p.h"
#include "qquickcontrol_p_p.h"
#include "qquickitemdelegate_p_p.h"
#include "qquickvelocitycalculator_p_p.h"
 
#include <QtGui/qstylehints.h>
#include <QtGui/private/qguiapplication_p.h>
#include <QtGui/private/qeventpoint_p.h>
#include <QtGui/qpa/qplatformtheme.h>
#include <QtQml/qqmlinfo.h>
#include <QtQuick/private/qquickanimation_p.h>
#include <QtQuick/private/qquicktransition_p.h>
#include <QtQuick/private/qquicktransitionmanager_p_p.h>
 
QT_BEGIN_NAMESPACE
 
 
namespace {
    typedef QQuickSwipeDelegateAttached Attached;
 
    Attached *attachedObject(QQuickItem *item) {
        return qobject_cast<Attached*>(qmlAttachedPropertiesObject<QQuickSwipeDelegate>(item, false));
    }
 
    enum PositionAnimation {
        DontAnimatePosition,
        AnimatePosition
    };
}
 
class QQuickSwipeTransitionManager : public QQuickTransitionManager
{
public:
    QQuickSwipeTransitionManager(QQuickSwipe *swipe);
 
    void transition(QQuickTransition *transition, qreal position);
 
protected:
    void finished() override;
 
private:
    QQuickSwipe *m_swipe = nullptr;
};
 
class QQuickSwipePrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QQuickSwipe)
 
public:
    QQuickSwipePrivate(QQuickSwipeDelegate *control) : control(control) { }
 
    static QQuickSwipePrivate *get(QQuickSwipe *swipe);
 
    QQuickItem *createDelegateItem(QQmlComponent *component);
    QQuickItem *showRelevantItemForPosition(qreal position);
    QQuickItem *createRelevantItemForDistance(qreal distance);
    void reposition(PositionAnimation animationPolicy);
    void createLeftItem();
    void createBehindItem();
    void createRightItem();
    void createAndShowLeftItem();
    void createAndShowBehindItem();
    void createAndShowRightItem();
 
    void warnAboutMixingDelegates();
    void warnAboutSettingDelegatesWhileVisible();
 
    bool hasDelegates() const;
 
    bool isTransitioning() const;
    void beginTransition(qreal position);
    void finishTransition();
 
    QQuickSwipeDelegate *control = nullptr;
    // Same range as position, but is set before press events so that we can
    // keep track of which direction the user must swipe when using left and right delegates.
    qreal positionBeforePress = 0;
    qreal position = 0;
    // A "less strict" version of complete that is true if complete was true
    // before the last press event.
    bool wasComplete = false;
    bool complete = false;
    bool enabled = true;
    bool waitForTransition = false;
    QQuickVelocityCalculator velocityCalculator;
    QQmlComponent *left = nullptr;
    QQmlComponent *behind = nullptr;
    QQmlComponent *right = nullptr;
    QQuickItem *leftItem = nullptr;
    QQuickItem *behindItem = nullptr;
    QQuickItem *rightItem = nullptr;
    QQuickTransition *transition = nullptr;
    QScopedPointer<QQuickSwipeTransitionManager> transitionManager;
};
 
QQuickSwipeTransitionManager::QQuickSwipeTransitionManager(QQuickSwipe *swipe)
    : m_swipe(swipe)
{
}
 
void QQuickSwipeTransitionManager::transition(QQuickTransition *transition, qreal position)
{
    qmlExecuteDeferred(transition);
 
    QQmlProperty defaultTarget(m_swipe, QLatin1String("position"));
    QQmlListProperty<QQuickAbstractAnimation> animations = transition->animations();
    const int count = animations.count(&animations);
    for (int i = 0; i < count; ++i) {
        QQuickAbstractAnimation *anim = animations.at(&animations, i);
        anim->setDefaultTarget(defaultTarget);
    }
 
    QList<QQuickStateAction> actions;
    actions << QQuickStateAction(m_swipe, QLatin1String("position"), position);
    QQuickTransitionManager::transition(actions, transition, m_swipe);
}
 
void QQuickSwipeTransitionManager::finished()
{
    QQuickSwipePrivate::get(m_swipe)->finishTransition();
}
 
QQuickSwipePrivate *QQuickSwipePrivate::get(QQuickSwipe *swipe)
{
    return swipe->d_func();
}
 
QQuickItem *QQuickSwipePrivate::createDelegateItem(QQmlComponent *component)
{
    // If we don't use the correct context, it won't be possible to refer to
    // the control's id from within the delegates.
    QQmlContext *context = component->creationContext();
    // The component might not have been created in QML, in which case
    // the creation context will be null and we have to create it ourselves.
    if (!context)
        context = qmlContext(control);
    QQuickItem *item = qobject_cast<QQuickItem*>(component->beginCreate(context));
    if (item) {
        item->setParentItem(control);
        component->completeCreate();
        QJSEngine::setObjectOwnership(item, QJSEngine::JavaScriptOwnership);
    }
    return item;
}
 
QQuickItem *QQuickSwipePrivate::showRelevantItemForPosition(qreal position)
{
    if (qFuzzyIsNull(position))
        return nullptr;
 
    if (behind) {
        createAndShowBehindItem();
        return behindItem;
    }
 
    if (right && position < 0.0) {
        createAndShowRightItem();
        return rightItem;
    }
 
    if (left && position > 0.0) {
        createAndShowLeftItem();
        return leftItem;
    }
 
    return nullptr;
}
 
QQuickItem *QQuickSwipePrivate::createRelevantItemForDistance(qreal distance)
{
    if (qFuzzyIsNull(distance))
        return nullptr;
 
    if (behind) {
        createBehindItem();
        return behindItem;
    }
 
    // a) If the position before the press was 0.0, we know that *any* movement
    // whose distance is negative will result in the right item being shown and
    // vice versa.
    // b) Once the control has been exposed (that is, swiped to the left or right,
    // and hence the position is either -1.0 or 1.0), we must use the width of the
    // relevant item to determine if the distance is larger than that item,
    // in order to know whether or not to display it.
    // c) If the control has been exposed, and the swipe is larger than the width
    // of the relevant item from which the swipe started from, we must show the
    // item on the other side (if any).
 
    if (right) {
        if ((distance < 0.0 && positionBeforePress == 0.0) /* a) */
            || (rightItem && positionBeforePress == -1.0 && distance < rightItem->width()) /* b) */
            || (leftItem && positionBeforePress == 1.0 && qAbs(distance) > leftItem->width())) /* c) */ {
            createRightItem();
            return rightItem;
        }
    }
 
    if (left) {
        if ((distance > 0.0 && positionBeforePress == 0.0) /* a) */
            || (leftItem && positionBeforePress == 1.0 && qAbs(distance) < leftItem->width()) /* b) */
            || (rightItem && positionBeforePress == -1.0 && qAbs(distance) > rightItem->width())) /* c) */ {
            createLeftItem();
            return leftItem;
        }
    }
 
    return nullptr;
}
 
void QQuickSwipePrivate::reposition(PositionAnimation animationPolicy)
{
    QQuickItem *relevantItem = showRelevantItemForPosition(position);
    const qreal relevantWidth = relevantItem ? relevantItem->width() : 0.0;
    const qreal contentItemX = position * relevantWidth + control->leftPadding();
 
    // "Behavior on x" relies on the property system to know when it should update,
    // so we can prevent it from animating by setting the x position directly.
    if (animationPolicy == AnimatePosition) {
        if (QQuickItem *contentItem = control->contentItem())
            contentItem->setProperty("x", contentItemX);
        if (QQuickItem *background = control->background())
            background->setProperty("x", position * relevantWidth);
    } else {
        if (QQuickItem *contentItem = control->contentItem())
            contentItem->setX(contentItemX);
        if (QQuickItem *background = control->background())
            background->setX(position * relevantWidth);
    }
}
 
void QQuickSwipePrivate::createLeftItem()
{
    if (!leftItem) {
        Q_Q(QQuickSwipe);
        q->setLeftItem(createDelegateItem(left));
        if (!leftItem)
            qmlWarning(control) << "Failed to create left item:" << left->errors();
    }
}
 
void QQuickSwipePrivate::createBehindItem()
{
    if (!behindItem) {
        Q_Q(QQuickSwipe);
        q->setBehindItem(createDelegateItem(behind));
        if (!behindItem)
            qmlWarning(control) << "Failed to create behind item:" << behind->errors();
    }
}
 
void QQuickSwipePrivate::createRightItem()
{
    if (!rightItem) {
        Q_Q(QQuickSwipe);
        q->setRightItem(createDelegateItem(right));
        if (!rightItem)
            qmlWarning(control) << "Failed to create right item:" << right->errors();
    }
}
 
void QQuickSwipePrivate::createAndShowLeftItem()
{
    createLeftItem();
 
    if (leftItem)
        leftItem->setVisible(true);
 
    if (rightItem)
        rightItem->setVisible(false);
}
 
void QQuickSwipePrivate::createAndShowBehindItem()
{
    createBehindItem();
 
    if (behindItem)
        behindItem->setVisible(true);
}
 
void QQuickSwipePrivate::createAndShowRightItem()
{
    createRightItem();
 
    // This item may have already existed but was hidden.
    if (rightItem)
        rightItem->setVisible(true);
 
    // The left item isn't visible when the right item is visible, so save rendering effort by hiding it.
    if (leftItem)
        leftItem->setVisible(false);
}
 
void QQuickSwipePrivate::warnAboutMixingDelegates()
{
    qmlWarning(control) << "cannot set both behind and left/right properties";
}
 
void QQuickSwipePrivate::warnAboutSettingDelegatesWhileVisible()
{
    qmlWarning(control) << "left/right/behind properties may only be set when swipe.position is 0";
}
 
bool QQuickSwipePrivate::hasDelegates() const
{
    return left || right || behind;
}
 
bool QQuickSwipePrivate::isTransitioning() const
{
    return transitionManager && transitionManager->isRunning();
}
 
void QQuickSwipePrivate::beginTransition(qreal newPosition)
{
    if (waitForTransition)
        return;
    Q_Q(QQuickSwipe);
    if (!transition) {
        q->setPosition(newPosition);
        finishTransition();
        return;
    }
 
    if (!transitionManager)
        transitionManager.reset(new QQuickSwipeTransitionManager(q));
 
    transitionManager->transition(transition, newPosition);
}
 
void QQuickSwipePrivate::finishTransition()
{
    Q_Q(QQuickSwipe);
    waitForTransition = false;
    q->setComplete(qFuzzyCompare(qAbs(position), qreal(1.0)));
    if (complete) {
        emit q->opened();
    } else {
        if (qFuzzyIsNull(position))
            wasComplete = false;
        emit q->closed();
    }
}
 
QQuickSwipe::QQuickSwipe(QQuickSwipeDelegate *control)
    : QObject(*(new QQuickSwipePrivate(control)))
{
}
 
QQmlComponent *QQuickSwipe::left() const
{
    Q_D(const QQuickSwipe);
    return d->left;
}
 
void QQuickSwipe::setLeft(QQmlComponent *left)
{
    Q_D(QQuickSwipe);
    if (left == d->left)
        return;
 
    if (d->behind) {
        d->warnAboutMixingDelegates();
        return;
    }
 
    if (!qFuzzyIsNull(d->position)) {
        d->warnAboutSettingDelegatesWhileVisible();
        return;
    }
 
    d->left = left;
 
    if (!d->left) {
        delete d->leftItem;
        d->leftItem = nullptr;
    }
 
    d->control->setFiltersChildMouseEvents(d->hasDelegates());
 
    emit leftChanged();
}
 
QQmlComponent *QQuickSwipe::behind() const
{
    Q_D(const QQuickSwipe);
    return d->behind;
}
 
void QQuickSwipe::setBehind(QQmlComponent *behind)
{
    Q_D(QQuickSwipe);
    if (behind == d->behind)
        return;
 
    if (d->left || d->right) {
        d->warnAboutMixingDelegates();
        return;
    }
 
    if (!qFuzzyIsNull(d->position)) {
        d->warnAboutSettingDelegatesWhileVisible();
        return;
    }
 
    d->behind = behind;
 
    if (!d->behind) {
        delete d->behindItem;
        d->behindItem = nullptr;
    }
 
    d->control->setFiltersChildMouseEvents(d->hasDelegates());
 
    emit behindChanged();
}
 
QQmlComponent *QQuickSwipe::right() const
{
    Q_D(const QQuickSwipe);
    return d->right;
}
 
void QQuickSwipe::setRight(QQmlComponent *right)
{
    Q_D(QQuickSwipe);
    if (right == d->right)
        return;
 
    if (d->behind) {
        d->warnAboutMixingDelegates();
        return;
    }
 
    if (!qFuzzyIsNull(d->position)) {
        d->warnAboutSettingDelegatesWhileVisible();
        return;
    }
 
    d->right = right;
 
    if (!d->right) {
        delete d->rightItem;
        d->rightItem = nullptr;
    }
 
    d->control->setFiltersChildMouseEvents(d->hasDelegates());
 
    emit rightChanged();
}
 
QQuickItem *QQuickSwipe::leftItem() const
{
    Q_D(const QQuickSwipe);
    return d->leftItem;
}
 
void QQuickSwipe::setLeftItem(QQuickItem *item)
{
    Q_D(QQuickSwipe);
    if (item == d->leftItem)
        return;
 
    delete d->leftItem;
    d->leftItem = item;
 
    if (d->leftItem) {
        d->leftItem->setParentItem(d->control);
 
        if (qFuzzyIsNull(d->leftItem->z()))
            d->leftItem->setZ(-2);
    }
 
    emit leftItemChanged();
}
 
QQuickItem *QQuickSwipe::behindItem() const
{
    Q_D(const QQuickSwipe);
    return d->behindItem;
}
 
void QQuickSwipe::setBehindItem(QQuickItem *item)
{
    Q_D(QQuickSwipe);
    if (item == d->behindItem)
        return;
 
    delete d->behindItem;
    d->behindItem = item;
 
    if (d->behindItem) {
        d->behindItem->setParentItem(d->control);
 
        if (qFuzzyIsNull(d->behindItem->z()))
            d->behindItem->setZ(-2);
    }
 
    emit behindItemChanged();
}
 
QQuickItem *QQuickSwipe::rightItem() const
{
    Q_D(const QQuickSwipe);
    return d->rightItem;
}
 
void QQuickSwipe::setRightItem(QQuickItem *item)
{
    Q_D(QQuickSwipe);
    if (item == d->rightItem)
        return;
 
    delete d->rightItem;
    d->rightItem = item;
 
    if (d->rightItem) {
        d->rightItem->setParentItem(d->control);
 
        if (qFuzzyIsNull(d->rightItem->z()))
            d->rightItem->setZ(-2);
    }
 
    emit rightItemChanged();
}
 
qreal QQuickSwipe::position() const
{
    Q_D(const QQuickSwipe);
    return d->position;
}
 
void QQuickSwipe::setPosition(qreal position)
{
    Q_D(QQuickSwipe);
    const qreal adjustedPosition = qBound<qreal>(-1.0, position, 1.0);
    if (adjustedPosition == d->position)
        return;
 
    d->position = adjustedPosition;
    d->reposition(AnimatePosition);
    emit positionChanged();
}
 
bool QQuickSwipe::isComplete() const
{
    Q_D(const QQuickSwipe);
    return d->complete;
}
 
void QQuickSwipe::setComplete(bool complete)
{
    Q_D(QQuickSwipe);
    if (complete == d->complete)
        return;
 
    d->complete = complete;
    emit completeChanged();
    if (d->complete)
        emit completed();
}
 
bool QQuickSwipe::isEnabled() const
{
    Q_D(const QQuickSwipe);
    return d->enabled;
}
 
void QQuickSwipe::setEnabled(bool enabled)
{
    Q_D(QQuickSwipe);
    if (enabled == d->enabled)
        return;
 
    d->enabled = enabled;
    emit enabledChanged();
}
 
QQuickTransition *QQuickSwipe::transition() const
{
    Q_D(const QQuickSwipe);
    return d->transition;
}
 
void QQuickSwipe::setTransition(QQuickTransition *transition)
{
    Q_D(QQuickSwipe);
    if (transition == d->transition)
        return;
 
    d->transition = transition;
    emit transitionChanged();
}
 
void QQuickSwipe::open(QQuickSwipeDelegate::Side side)
{
    Q_D(QQuickSwipe);
    if (qFuzzyCompare(qAbs(d->position), qreal(1.0)))
        return;
 
    if ((side != QQuickSwipeDelegate::Left && side != QQuickSwipeDelegate::Right)
            || (!d->left && !d->behind && side == QQuickSwipeDelegate::Left)
            || (!d->right && !d->behind && side == QQuickSwipeDelegate::Right))
        return;
 
    d->beginTransition(side);
    d->wasComplete = true;
    d->velocityCalculator.reset();
    d->positionBeforePress = d->position;
}
 
void QQuickSwipe::close()
{
    Q_D(QQuickSwipe);
    if (qFuzzyIsNull(d->position))
        return;
 
    if (d->control->isPressed()) {
        // We don't support closing when we're pressed; release() or clicked() should be used instead.
        return;
    }
 
    d->beginTransition(0.0);
    d->waitForTransition = true;
    d->wasComplete = false;
    d->positionBeforePress = 0.0;
    d->velocityCalculator.reset();
}
 
QQuickSwipeDelegatePrivate::QQuickSwipeDelegatePrivate(QQuickSwipeDelegate *control)
    : swipe(control)
{
}
 
void QQuickSwipeDelegatePrivate::resizeBackground()
{
    if (!background)
        return;
 
    resizingBackground = true;
 
    QQuickItemPrivate *p = QQuickItemPrivate::get(background);
    const bool extraAllocated = extra.isAllocated();
    // Don't check for or set the x here since it will just be overwritten by reposition().
    if (((!p->widthValid() || !extraAllocated || !extra->hasBackgroundWidth))
            || (extraAllocated && (extra->hasLeftInset || extra->hasRightInset))) {
        background->setWidth(width - getLeftInset() - getRightInset());
    }
    if (((!p->heightValid() || !extraAllocated || !extra->hasBackgroundHeight) && qFuzzyIsNull(background->y()))
            || (extraAllocated && (extra->hasTopInset || extra->hasBottomInset))) {
        background->setY(getTopInset());
        background->setHeight(height - getTopInset() - getBottomInset());
    }
 
    resizingBackground = false;
}
 
bool QQuickSwipeDelegatePrivate::handleMousePressEvent(QQuickItem *item, QMouseEvent *event)
{
    Q_Q(QQuickSwipeDelegate);
    const auto posInItem = item->mapToItem(q, event->position().toPoint());
    QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&swipe);
    // If the position is 0, we want to handle events ourselves - we don't want child items to steal them.
    // This code will only get called when a child item has been created;
    // events will go through the regular channels (mousePressEvent()) until then.
    if (qFuzzyIsNull(swipePrivate->position)) {
        q->mousePressEvent(event);
        // The press point could be incorrect if the press happened over a child item,
        // so we correct it after calling the base class' mousePressEvent(), rather
        // than having to duplicate its code just so we can set the pressPoint.
        setPressPoint(posInItem);
        return true;
    }
 
    // If the delegate is swiped open, send the event to the exposed item,
    // in case it's an interactive child (like a Button).
    if (swipePrivate->complete)
        forwardMouseEvent(event, item, posInItem);
 
    // The position is non-zero, this press could be either for a delegate or the control itself
    // (the control can be clicked to e.g. close the swipe). Either way, we must begin measuring
    // mouse movement in case it turns into a swipe, in which case we grab the mouse.
    swipePrivate->positionBeforePress = swipePrivate->position;
    swipePrivate->velocityCalculator.startMeasuring(event->position().toPoint(), event->timestamp());
    setPressPoint(item->mapToItem(q, event->position().toPoint()));
 
    // When a delegate or any of its children uses the attached properties and signals,
    // it declares that it wants mouse events.
    const bool delivered = attachedObjectsSetPressed(item, event->scenePosition(), true);
    if (delivered)
        event->accept();
    return delivered;
}
 
bool QQuickSwipeDelegatePrivate::handleMouseMoveEvent(QQuickItem *item, QMouseEvent *event)
{
    Q_Q(QQuickSwipeDelegate);
 
    if (holdTimer > 0) {
        if (QLineF(pressPoint, event->position()).length() > QGuiApplication::styleHints()->startDragDistance())
            stopPressAndHold();
    }
 
    // The delegate can still be pressed when swipe.enabled is false,
    // but the mouse moving shouldn't have any effect on swipe.position.
    QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&swipe);
    if (!swipePrivate->enabled)
        return false;
 
    // Protect against division by zero.
    if (width == 0)
        return false;
 
    // Don't bother reacting to events if we don't have any delegates.
    if (!swipePrivate->left && !swipePrivate->right && !swipePrivate->behind)
        return false;
 
    if (item != q && swipePrivate->complete) {
        // If the delegate is swiped open, send the event to the exposed item,
        // in case it's an interactive child (like a Button).
        const auto posInItem = item->mapToItem(q, event->position().toPoint());
        forwardMouseEvent(event, item, posInItem);
    }
 
    // Don't handle move events for the control if it wasn't pressed.
    if (item == q && !pressed)
        return false;
 
    const qreal distance = (event->globalPosition().x() != qInf() && event->globalPosition().y() != qInf()) ?
                              (item->mapFromGlobal(event->globalPosition()) -
                               item->mapFromGlobal(event->points().first().globalPressPosition())).x() : 0;
    if (!q->keepMouseGrab()) {
        // We used to use the custom threshold that QQuickDrawerPrivate::grabMouse used,
        // but since it's larger than what Flickable uses, it results in Flickable
        // stealing events from us (QTBUG-50045), so now we use the default.
        const bool overThreshold = QQuickWindowPrivate::dragOverThreshold(distance, Qt::XAxis, event);
        if (window && overThreshold) {
            QQuickItem *grabber = q->window()->mouseGrabberItem();
            if (!grabber || !grabber->keepMouseGrab()) {
                q->grabMouse();
                q->setKeepMouseGrab(true);
                q->setPressed(true);
                swipe.setComplete(false);
 
                attachedObjectsSetPressed(item, event->scenePosition(), false, true);
            }
        }
    }
 
    if (q->keepMouseGrab()) {
        // Ensure we don't try to calculate a position when the user tried to drag
        // to the left when the left item is already exposed, and vice versa.
        // The code below assumes that the drag is valid, so if we don't have this check,
        // the wrong items are visible and the swiping wraps.
        if (swipePrivate->behind
            || ((swipePrivate->left || swipePrivate->right)
                && (qFuzzyIsNull(swipePrivate->positionBeforePress)
                    || (swipePrivate->positionBeforePress == -1.0 && distance >= 0.0)
                    || (swipePrivate->positionBeforePress == 1.0 && distance <= 0.0)))) {
 
            // We must instantiate the items here so that we can calculate the
            // position against the width of the relevant item.
            QQuickItem *relevantItem = swipePrivate->createRelevantItemForDistance(distance);
            // If there isn't any relevant item, the user may have swiped back to the 0 position,
            // or they swiped back to a position that is equal to positionBeforePress.
            const qreal normalizedDistance = relevantItem ? distance / relevantItem->width() : 0.0;
            qreal position = 0;
 
            // If the control was exposed before the drag begun, the distance should be inverted.
            // For example, if the control had been swiped to the right, the position would be 1.0.
            // If the control was then swiped to the left by a distance of -20 pixels, the normalized
            // distance might be -0.2, for example, which cannot be used as the position; the swipe
            // started from the right, so we account for that by adding the position.
            if (qFuzzyIsNull(normalizedDistance)) {
                // There are two cases when the normalizedDistance can be 0,
                // and we must distinguish between them:
                //
                // a) The swipe returns to the position that it was at before the press event.
                // In this case, the distance will be 0.
                // There would have been many position changes in the meantime, so we can't just
                // ignore the move event; we have to set position to what it was before the press.
                //
                // b) If the position was at, 1.0, for example, and the control was then swiped
                // to the left by the exact width of the left item, there won't be any relevant item
                // (because the swipe's position would be at 0.0). In turn, the normalizedDistance
                // would be 0 (because of the lack of a relevant item), but the distance will be non-zero.
                position = qFuzzyIsNull(distance) ? swipePrivate->positionBeforePress : 0;
            } else if (!swipePrivate->wasComplete) {
                position = normalizedDistance;
            } else {
                position = distance > 0 ? normalizedDistance - 1.0 : normalizedDistance + 1.0;
            }
 
            if (swipePrivate->isTransitioning())
                swipePrivate->transitionManager->cancel();
            swipe.setPosition(position);
        }
    } else {
        // The swipe wasn't initiated.
        if (event->position().toPoint().y() < 0 || event->position().toPoint().y() > height) {
            // The mouse went outside the vertical bounds of the control, so
            // we should no longer consider it pressed.
            q->setPressed(false);
        }
    }
 
    event->accept();
 
    return q->keepMouseGrab();
}
 
static const qreal exposeVelocityThreshold = 300.0;
 
bool QQuickSwipeDelegatePrivate::handleMouseReleaseEvent(QQuickItem *item, QMouseEvent *event)
{
    Q_Q(QQuickSwipeDelegate);
    QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&swipe);
    swipePrivate->velocityCalculator.stopMeasuring(event->position().toPoint(), event->timestamp());
 
    const bool hadGrabbedMouse = q->keepMouseGrab();
    q->setKeepMouseGrab(false);
 
    // QQuickSwipe::close() doesn't allow closing while pressed, but now we're releasing.
    // So set the pressed state false if this release _could_ result in closing, so that check can be bypassed.
    if (!qIsNull(swipePrivate->position))
        q->setPressed(false);
 
    // Animations for the background and contentItem delegates are typically
    // only enabled when !control.down, so that the animations aren't running
    // when the user is swiping. To ensure that the animations are enabled
    // *before* the positions of these delegates change (via the swipe.setPosition() calls below),
    // we must cancel the press. QQuickAbstractButton::mouseUngrabEvent() does this
    // for us, but by then it's too late.
    if (hadGrabbedMouse) {
        // TODO: this is copied from QQuickAbstractButton::mouseUngrabEvent().
        // Eventually it should be moved into a private helper so that we don't have to duplicate it.
        q->setPressed(false);
        stopPressRepeat();
        stopPressAndHold();
        emit q->canceled();
    }
 
    // Inform the given item that the mouse is released, in case it's an interactive child.
    if (item != q && (swipePrivate->complete || swipePrivate->wasComplete))
        forwardMouseEvent(event, item, item->mapFromScene(event->scenePosition()));
 
    // The control can be exposed by either swiping past the halfway mark, or swiping fast enough.
    const qreal swipeVelocity = swipePrivate->velocityCalculator.velocity().x();
    if (swipePrivate->position > 0.5 ||
        (swipePrivate->position > 0.0 && swipeVelocity > exposeVelocityThreshold)) {
        swipePrivate->beginTransition(1.0);
        swipePrivate->wasComplete = true;
    } else if (swipePrivate->position < -0.5 ||
        (swipePrivate->position < 0.0 && swipeVelocity < -exposeVelocityThreshold)) {
        swipePrivate->beginTransition(-1.0);
        swipePrivate->wasComplete = true;
    } else if (!swipePrivate->isTransitioning()) {
        // The position is either <= 0.5 or >= -0.5, so the position should go to 0.
        // However, if the position was already 0 or close to it, we were just clicked,
        // and we don't need to start a transition.
        if (!qFuzzyIsNull(swipePrivate->position))
            swipePrivate->beginTransition(0.0);
        swipePrivate->wasComplete = false;
    }
 
    // Inform any QQuickSwipeDelegateAttached objects that the mouse is released.
    attachedObjectsSetPressed(item, event->scenePosition(), false);
 
    // Only consume child events if we had grabbed the mouse.
    return hadGrabbedMouse;
}
 
void QQuickSwipeDelegatePrivate::forwardMouseEvent(QMouseEvent *event, QQuickItem *destination, QPointF localPos)
{
    Q_Q(QQuickSwipeDelegate);
    QMutableSinglePointEvent localizedEvent(*event);
    QMutableEventPoint::setPosition(localizedEvent.point(0), localPos);
    QGuiApplication::sendEvent(destination, &localizedEvent);
    q->setPressed(!localizedEvent.isAccepted());
}
 
bool QQuickSwipeDelegatePrivate::attachedObjectsSetPressed(QQuickItem *item, QPointF scenePos, bool pressed, bool cancel)
{
    bool found = false;
    QVarLengthArray<QQuickItem *, 16> itemAndChildren;
    itemAndChildren.append(item);
    for (int i = 0; i < itemAndChildren.size(); ++i) {
        auto item = itemAndChildren.at(i);
        auto posInItem = item->mapFromScene(scenePos);
        if (item->contains(posInItem)) {
            if (Attached *attached = attachedObject(item)) {
                const bool wasPressed = attached->isPressed();
                attached->setPressed(pressed);
                if (wasPressed && !pressed && !cancel)
                    emit attached->clicked();
                found = true;
            }
        }
        for (auto child : item->childItems())
            itemAndChildren.append(child);
    }
    return found;
}
 
static void warnIfHorizontallyAnchored(QQuickItem *item, const QString &itemName)
{
    if (!item)
        return;
 
    QQuickAnchors *anchors = QQuickItemPrivate::get(item)->_anchors;
    if (anchors && (anchors->fill() || anchors->centerIn() || anchors->left().item || anchors->right().item)
            && !item->property("_q_QQuickSwipeDelegate_warned").toBool()) {
        qmlWarning(item) << QString::fromLatin1("SwipeDelegate: cannot use horizontal anchors with %1; unable to layout the item.").arg(itemName);
        item->setProperty("_q_QQuickSwipeDelegate_warned", true);
    }
}
 
void QQuickSwipeDelegatePrivate::resizeContent()
{
    warnIfHorizontallyAnchored(background, QStringLiteral("background"));
    warnIfHorizontallyAnchored(contentItem, QStringLiteral("contentItem"));
 
    // If the background and contentItem are repositioned due to a swipe,
    // we don't want to call QQuickControlPrivate's implementation of this function,
    // as it repositions the contentItem to be visible.
    // However, we still want to position the contentItem vertically
    // and resize it (in case the control was resized while open).
    QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&swipe);
    if (!swipePrivate->complete) {
        QQuickItemDelegatePrivate::resizeContent();
    } else if (contentItem) {
        Q_Q(QQuickSwipeDelegate);
        contentItem->setY(q->topPadding());
        contentItem->setWidth(q->availableWidth());
        contentItem->setHeight(q->availableHeight());
    }
}
 
QPalette QQuickSwipeDelegatePrivate::defaultPalette() const
{
    return QQuickTheme::palette(QQuickTheme::ListView);
}
 
QQuickItem *QQuickSwipeDelegatePrivate::getPressedItem(QQuickItem *childItem, QMouseEvent *event) const
{
    if (!childItem || !event)
        return nullptr;
 
    QQuickItem *item = nullptr;
 
    if (childItem->acceptedMouseButtons() &&
            childItem->contains(childItem->mapFromScene(event->scenePosition()))) {
        item = childItem;
    } else {
        const auto &childItems = childItem->childItems();
        for (const auto &child: childItems) {
            if ((item = getPressedItem(child, event)))
                break;
        }
    }
 
    return item;
}
 
QQuickSwipeDelegate::QQuickSwipeDelegate(QQuickItem *parent)
    : QQuickItemDelegate(*(new QQuickSwipeDelegatePrivate(this)), parent)
{
    // QQuickSwipeDelegate still depends on synthesized mouse events
    setAcceptTouchEvents(false);
}
 
QQuickSwipe *QQuickSwipeDelegate::swipe() const
{
    Q_D(const QQuickSwipeDelegate);
    return const_cast<QQuickSwipe*>(&d->swipe);
}
 
QQuickSwipeDelegateAttached *QQuickSwipeDelegate::qmlAttachedProperties(QObject *object)
{
    return new QQuickSwipeDelegateAttached(object);
}
 
static bool isChildOrGrandchildOf(QQuickItem *child, QQuickItem *item)
{
    return item && (child == item || item->isAncestorOf(child));
}
 
bool QQuickSwipeDelegate::childMouseEventFilter(QQuickItem *child, QEvent *event)
{
    Q_D(QQuickSwipeDelegate);
    // The contentItem is, by default, usually a non-interactive item like Text, and
    // the same applies to the background. This means that simply stacking the left/right/behind
    // items before these items won't allow us to get mouse events when the control is not currently exposed
    // but has been previously. Therefore, we instead call setFiltersChildMouseEvents(true) in the constructor
    // and filter out child events only when the child is the left/right/behind item.
    const QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&d->swipe);
    if (!isChildOrGrandchildOf(child, swipePrivate->leftItem) && !isChildOrGrandchildOf(child, swipePrivate->behindItem)
        && !isChildOrGrandchildOf(child, swipePrivate->rightItem)) {
        return false;
    }
 
    switch (event->type()) {
    case QEvent::MouseButtonPress: {
        return d->handleMousePressEvent(child, static_cast<QMouseEvent *>(event));
    } case QEvent::MouseMove: {
        return d->handleMouseMoveEvent(child, static_cast<QMouseEvent *>(event));
    } case QEvent::MouseButtonRelease: {
        // Make sure that the control gets release events if it has created child
        // items that are stealing events from it.
        QMouseEvent *mouseEvent = static_cast<QMouseEvent *>(event);
        QQuickItemDelegate::mouseReleaseEvent(mouseEvent);
        return d->handleMouseReleaseEvent(child, mouseEvent);
    } case QEvent::UngrabMouse: {
        // If the mouse was pressed over e.g. rightItem and then dragged down,
        // the ListView would eventually grab the mouse, at which point we must
        // clear the pressed flag so that it doesn't stay pressed after the release.
        Attached *attached = attachedObject(child);
        if (attached)
            attached->setPressed(false);
        return false;
    } default:
        return false;
    }
}
 
// We only override this to set positionBeforePress;
// otherwise, it's the same as the base class implementation.
void QQuickSwipeDelegate::mousePressEvent(QMouseEvent *event)
{
    Q_D(QQuickSwipeDelegate);
    QQuickItemDelegate::mousePressEvent(event);
 
    QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&d->swipe);
    if (!swipePrivate->enabled)
        return;
 
    swipePrivate->positionBeforePress = swipePrivate->position;
    swipePrivate->velocityCalculator.startMeasuring(event->position().toPoint(), event->timestamp());
 
    if (swipePrivate->complete) {
        d->pressedItem = d->getPressedItem(d->swipe.rightItem(), event);
        if (!d->pressedItem)
            d->pressedItem = d->getPressedItem(d->swipe.leftItem(), event);
        if (d->pressedItem)
            d->handleMousePressEvent(d->pressedItem, event);
    }
}
 
void QQuickSwipeDelegate::mouseMoveEvent(QMouseEvent *event)
{
    Q_D(QQuickSwipeDelegate);
    if (filtersChildMouseEvents())
        d->handleMouseMoveEvent(this, event);
    else
        QQuickItemDelegate::mouseMoveEvent(event);
    if (d->pressedItem)
        d->handleMouseMoveEvent(d->pressedItem, event);
}
 
void QQuickSwipeDelegate::mouseReleaseEvent(QMouseEvent *event)
{
    Q_D(QQuickSwipeDelegate);
    if (!filtersChildMouseEvents() || !d->handleMouseReleaseEvent(this, event))
        QQuickItemDelegate::mouseReleaseEvent(event);
 
    if (d->pressedItem) {
        if (d->pressedItem->acceptedMouseButtons())
            d->handleMouseReleaseEvent(d->pressedItem, event);
        d->pressedItem = nullptr;
    }
}
 
void QQuickSwipeDelegate::mouseUngrabEvent()
{
    Q_D(QQuickSwipeDelegate);
    setPressed(false);
 
    auto item = d->swipe.rightItem();
    if (item) {
        if (auto control = qmlobject_cast<QQuickControl *>(item))
            QQuickControlPrivate::get(control)->handleUngrab();
        Attached *attached = attachedObject(item);
        if (attached)
            attached->setPressed(false);
    } else {
        item = d->swipe.leftItem();
        if (item) {
            if (auto control = qmlobject_cast<QQuickControl *>(item))
                QQuickControlPrivate::get(control)->handleUngrab();
            Attached *attached = attachedObject(item);
            if (attached)
                attached->setPressed(false);
        }
    }
 
    d->pressedItem = nullptr;
}
 
void QQuickSwipeDelegate::touchEvent(QTouchEvent *event)
{
    // Don't allow QQuickControl accept the touch event, because QQuickSwipeDelegate
    // is still based on synthesized mouse events
    event->ignore();
}
 
void QQuickSwipeDelegate::componentComplete()
{
    Q_D(QQuickSwipeDelegate);
    QQuickItemDelegate::componentComplete();
    QQuickSwipePrivate::get(&d->swipe)->reposition(DontAnimatePosition);
}
 
void QQuickSwipeDelegate::geometryChange(const QRectF &newGeometry, const QRectF &oldGeometry)
{
    Q_D(QQuickSwipeDelegate);
    QQuickControl::geometryChange(newGeometry, oldGeometry);
 
    if (isComponentComplete() && !qFuzzyCompare(newGeometry.width(), oldGeometry.width())) {
        QQuickSwipePrivate *swipePrivate = QQuickSwipePrivate::get(&d->swipe);
        swipePrivate->reposition(DontAnimatePosition);
    }
}
 
QFont QQuickSwipeDelegate::defaultFont() const
{
    return QQuickTheme::font(QQuickTheme::ListView);
}
 
#if QT_CONFIG(accessibility)
QAccessible::Role QQuickSwipeDelegate::accessibleRole() const
{
    return QAccessible::ListItem;
}
#endif
 
class QQuickSwipeDelegateAttachedPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QQuickSwipeDelegateAttached)
 
public:
    // True when left/right/behind is non-interactive and is pressed.
    bool pressed = false;
};
 
QQuickSwipeDelegateAttached::QQuickSwipeDelegateAttached(QObject *object)
    : QObject(*(new QQuickSwipeDelegateAttachedPrivate), object)
{
    QQuickItem *item = qobject_cast<QQuickItem *>(object);
    if (item) {
        // This allows us to be notified when an otherwise non-interactive item
        // is pressed and clicked. The alternative is much more more complex:
        // iterating through children that contain the event pos and finding
        // the first one with an attached object.
        item->setAcceptedMouseButtons(Qt::AllButtons);
    } else {
        qWarning() << "Attached properties of SwipeDelegate must be accessed through an Item";
    }
}
 
bool QQuickSwipeDelegateAttached::isPressed() const
{
    Q_D(const QQuickSwipeDelegateAttached);
    return d->pressed;
}
 
void QQuickSwipeDelegateAttached::setPressed(bool pressed)
{
    Q_D(QQuickSwipeDelegateAttached);
    if (pressed == d->pressed)
        return;
 
    d->pressed = pressed;
    emit pressedChanged();
}
 
QT_END_NAMESPACE
 
#include "moc_qquickswipe_p.cpp"
#include "moc_qquickswipedelegate_p.cpp"