qquickwheelhandler.cpp

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// Copyright (C) 2020 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 "qquickwheelhandler_p.h"
#include "qquickwheelhandler_p_p.h"
#include <QtQuick/private/qquickitem_p.h>
#include <QLoggingCategory>
#include <QtMath>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(lcWheelHandler, "qt.quick.handler.wheel")
 
 
QQuickWheelHandler::QQuickWheelHandler(QQuickItem *parent)
    : QQuickSinglePointHandler(*(new QQuickWheelHandlerPrivate), parent)
{
    setAcceptedDevices(QInputDevice::DeviceType::Mouse);
}
 
Qt::Orientation QQuickWheelHandler::orientation() const
{
    Q_D(const QQuickWheelHandler);
    return d->orientation;
}
 
void QQuickWheelHandler::setOrientation(Qt::Orientation orientation)
{
    Q_D(QQuickWheelHandler);
    if (d->orientation == orientation)
        return;
 
    d->orientation = orientation;
    emit orientationChanged();
}
 
bool QQuickWheelHandler::isInvertible() const
{
    Q_D(const QQuickWheelHandler);
    return d->invertible;
}
 
void QQuickWheelHandler::setInvertible(bool invertible)
{
    Q_D(QQuickWheelHandler);
    if (d->invertible == invertible)
        return;
 
    d->invertible = invertible;
    emit invertibleChanged();
}
 
qreal QQuickWheelHandler::activeTimeout() const
{
    Q_D(const QQuickWheelHandler);
    return d->activeTimeout;
}
 
void QQuickWheelHandler::setActiveTimeout(qreal timeout)
{
    Q_D(QQuickWheelHandler);
    if (qFuzzyCompare(d->activeTimeout, timeout))
        return;
 
    if (timeout < 0) {
        qWarning("activeTimeout must be positive");
        return;
    }
 
    d->activeTimeout = timeout;
    emit activeTimeoutChanged();
}
 
qreal QQuickWheelHandler::rotation() const
{
    Q_D(const QQuickWheelHandler);
    return d->rotation * d->rotationScale;
}
 
void QQuickWheelHandler::setRotation(qreal rotation)
{
    Q_D(QQuickWheelHandler);
    if (qFuzzyCompare(d->rotation, rotation / d->rotationScale))
        return;
 
    d->rotation = rotation / d->rotationScale;
    emit rotationChanged();
}
 
qreal QQuickWheelHandler::rotationScale() const
{
    Q_D(const QQuickWheelHandler);
    return d->rotationScale;
}
 
void QQuickWheelHandler::setRotationScale(qreal rotationScale)
{
    Q_D(QQuickWheelHandler);
    if (qFuzzyCompare(d->rotationScale, rotationScale))
        return;
    if (qFuzzyIsNull(rotationScale)) {
        qWarning("rotationScale cannot be set to zero");
        return;
    }
 
    d->rotationScale = rotationScale;
    emit rotationScaleChanged();
}
 
QString QQuickWheelHandler::property() const
{
    Q_D(const QQuickWheelHandler);
    return d->propertyName;
}
 
void QQuickWheelHandler::setProperty(const QString &propertyName)
{
    Q_D(QQuickWheelHandler);
    if (d->propertyName == propertyName)
        return;
 
    d->propertyName = propertyName;
    d->metaPropertyDirty = true;
    emit propertyChanged();
}
 
qreal QQuickWheelHandler::targetScaleMultiplier() const
{
    Q_D(const QQuickWheelHandler);
    return d->targetScaleMultiplier;
}
 
void QQuickWheelHandler::setTargetScaleMultiplier(qreal targetScaleMultiplier)
{
    Q_D(QQuickWheelHandler);
    if (qFuzzyCompare(d->targetScaleMultiplier, targetScaleMultiplier))
        return;
 
    d->targetScaleMultiplier = targetScaleMultiplier;
    emit targetScaleMultiplierChanged();
}
 
bool QQuickWheelHandler::isTargetTransformAroundCursor() const
{
    Q_D(const QQuickWheelHandler);
    return d->targetTransformAroundCursor;
}
 
void QQuickWheelHandler::setTargetTransformAroundCursor(bool ttac)
{
    Q_D(QQuickWheelHandler);
    if (d->targetTransformAroundCursor == ttac)
        return;
 
    d->targetTransformAroundCursor = ttac;
    emit targetTransformAroundCursorChanged();
}
 
bool QQuickWheelHandler::isBlocking() const
{
    Q_D(const QQuickWheelHandler);
    return d->blocking;
}
 
void QQuickWheelHandler::setBlocking(bool blocking)
{
    Q_D(QQuickWheelHandler);
    if (d->blocking == blocking)
        return;
 
    d->blocking = blocking;
    emit blockingChanged();
}
 
bool QQuickWheelHandler::wantsPointerEvent(QPointerEvent *event)
{
    if (!event)
        return false;
    if (event->type() != QEvent::Wheel)
        return false;
    QWheelEvent *we = static_cast<QWheelEvent *>(event);
    if (!acceptedDevices().testFlag(QPointingDevice::DeviceType::TouchPad)
            && we->source() != Qt::MouseEventNotSynthesized)
        return false;
    if (!active()) {
        switch (orientation()) {
        case Qt::Horizontal:
            if (!(we->angleDelta().x()) && !(we->pixelDelta().x()))
                return false;
            break;
        case Qt::Vertical:
            if (!(we->angleDelta().y()) && !(we->pixelDelta().y()))
                return false;
            break;
        }
    }
    auto &point = event->point(0);
    if (QQuickPointerDeviceHandler::wantsPointerEvent(event) && wantsEventPoint(event, point) && parentContains(point)) {
        setPointId(point.id());
        return true;
    }
    return false;
}
 
void QQuickWheelHandler::handleEventPoint(QPointerEvent *ev, QEventPoint &point)
{
    Q_D(QQuickWheelHandler);
    QQuickSinglePointHandler::handleEventPoint(ev, point);
 
    if (ev->type() != QEvent::Wheel)
        return;
    const QWheelEvent *event = static_cast<const QWheelEvent *>(ev);
    setActive(true); // ScrollEnd will not happen unless it was already active (see setActive(false) below)
    if (d->blocking)
        point.setAccepted();
    qreal inversion = !d->invertible && event->isInverted() ? -1 : 1;
    qreal angleDelta = inversion * qreal(orientation() == Qt::Horizontal ? event->angleDelta().x() :
                                                                           event->angleDelta().y()) / 8;
    d->rotation += angleDelta;
    emit rotationChanged();
 
    d->wheelEvent.reset(event);
    emit wheel(&d->wheelEvent);
    if (!d->propertyName.isEmpty() && target()) {
        QQuickItem *t = target();
        // writing target()'s property is done via QMetaProperty::write() so that any registered interceptors can react.
        if (d->propertyName == QLatin1String("scale")) {
            qreal multiplier = qPow(d->targetScaleMultiplier, angleDelta * d->rotationScale / 15); // wheel "clicks"
            const QPointF centroidParentPos = t->parentItem()->mapFromScene(point.scenePosition());
            const QPointF positionWas = t->position();
            const qreal scaleWas = t->scale();
            const qreal activePropertyValue = scaleWas * multiplier;
            qCDebug(lcWheelHandler) << objectName() << "angle delta" << event->angleDelta() << "pixel delta" << event->pixelDelta()
                                    << "@" << point.position() << "in parent" << centroidParentPos
                                    << "in scene" << point.scenePosition()
                                    << "multiplier" << multiplier << "scale" << scaleWas
                                    << "->" << activePropertyValue;
            d->targetMetaProperty().write(t, activePropertyValue);
            if (d->targetTransformAroundCursor) {
                // If an interceptor intervened, scale may now be different than we asked for.  Adjust accordingly.
                multiplier = t->scale() / scaleWas;
                const QPointF adjPos = QQuickItemPrivate::get(t)->adjustedPosForTransform(
                            centroidParentPos, positionWas, QVector2D(), scaleWas, multiplier, t->rotation(), 0);
                qCDebug(lcWheelHandler) << "adjusting item pos" << adjPos << "in scene" << t->parentItem()->mapToScene(adjPos);
                t->setPosition(adjPos);
            }
        } else if (d->propertyName == QLatin1String("rotation")) {
            const QPointF positionWas = t->position();
            const qreal rotationWas = t->rotation();
            const qreal activePropertyValue = rotationWas + angleDelta * d->rotationScale;
            const QPointF centroidParentPos = t->parentItem()->mapFromScene(point.scenePosition());
            qCDebug(lcWheelHandler) << objectName() << "angle delta" << event->angleDelta() << "pixel delta" << event->pixelDelta()
                                    << "@" << point.position() << "in parent" << centroidParentPos
                                    << "in scene" << point.scenePosition() << "rotation" << t->rotation()
                                    << "->" << activePropertyValue;
            d->targetMetaProperty().write(t, activePropertyValue);
            if (d->targetTransformAroundCursor) {
                // If an interceptor intervened, rotation may now be different than we asked for.  Adjust accordingly.
                const QPointF adjPos = QQuickItemPrivate::get(t)->adjustedPosForTransform(
                            centroidParentPos, positionWas, QVector2D(),
                            t->scale(), 1, rotationWas, t->rotation() - rotationWas);
                qCDebug(lcWheelHandler) << "adjusting item pos" << adjPos << "in scene" << t->parentItem()->mapToScene(adjPos);
                t->setPosition(adjPos);
            }
        } else {
            qCDebug(lcWheelHandler) << objectName() << "angle delta" << event->angleDelta() << "scaled" << angleDelta
                                    << "total" << d->rotation << "pixel delta" << event->pixelDelta()
                                    << "@" << point.position() << "in scene" << point.scenePosition() << "rotation" << t->rotation();
            qreal delta = 0;
            if (event->hasPixelDelta()) {
                delta = inversion * d->rotationScale * qreal(orientation() == Qt::Horizontal ? event->pixelDelta().x() : event->pixelDelta().y());
                qCDebug(lcWheelHandler) << "changing target" << d->propertyName << "by pixel delta" << delta << "from" << event;
            } else {
                delta = angleDelta * d->rotationScale;
                qCDebug(lcWheelHandler) << "changing target" << d->propertyName << "by scaled angle delta" << delta << "from" << event;
            }
            bool ok = false;
            qreal value = d->targetMetaProperty().read(t).toReal(&ok);
            if (ok)
                d->targetMetaProperty().write(t, value + qreal(delta));
            else
                qWarning() << "failed to read property" << d->propertyName << "of" << t;
        }
    }
    switch (event->phase()) {
    case Qt::ScrollEnd:
        qCDebug(lcWheelHandler) << objectName() << "deactivating due to ScrollEnd phase";
        setActive(false);
        break;
    case Qt::NoScrollPhase:
        d->deactivationTimer.start(qRound(d->activeTimeout * 1000), this);
        break;
    case Qt::ScrollBegin:
    case Qt::ScrollUpdate:
    case Qt::ScrollMomentum:
        break;
    }
}
 
void QQuickWheelHandler::onTargetChanged(QQuickItem *oldTarget)
{
    Q_UNUSED(oldTarget);
    Q_D(QQuickWheelHandler);
    d->metaPropertyDirty = true;
}
 
void QQuickWheelHandler::onActiveChanged()
{
    Q_D(QQuickWheelHandler);
    if (!active())
        d->deactivationTimer.stop();
}
 
void QQuickWheelHandler::timerEvent(QTimerEvent *event)
{
    Q_D(const QQuickWheelHandler);
    if (event->timerId() == d->deactivationTimer.timerId()) {
        qCDebug(lcWheelHandler) << objectName() << "deactivating due to timeout";
        setActive(false);
    }
}
 
QQuickWheelHandlerPrivate::QQuickWheelHandlerPrivate()
    : QQuickSinglePointHandlerPrivate()
{
}
 
QMetaProperty &QQuickWheelHandlerPrivate::targetMetaProperty() const
{
    Q_Q(const QQuickWheelHandler);
    if (metaPropertyDirty && q->target()) {
        if (!propertyName.isEmpty()) {
            const QMetaObject *targetMeta = q->target()->metaObject();
            metaProperty = targetMeta->property(
                        targetMeta->indexOfProperty(propertyName.toLocal8Bit().constData()));
        }
        metaPropertyDirty = false;
    }
    return metaProperty;
}
 
QT_END_NAMESPACE
 
#include "moc_qquickwheelhandler_p.cpp"