qquickpointerhandler.cpp

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// Copyright (C) 2018 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 "qquickpointerhandler_p.h"
#include "qquickpointerhandler_p_p.h"
#include <QtQuick/private/qquickitem_p.h>
#include <QtQuick/private/qquickhandlerpoint_p.h>
#include <QtQuick/private/qquickdeliveryagent_p_p.h>
#include <QtGui/private/qinputdevice_p.h>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(lcPointerHandlerDispatch, "qt.quick.handler.dispatch")
Q_LOGGING_CATEGORY(lcPointerHandlerGrab, "qt.quick.handler.grab")
Q_LOGGING_CATEGORY(lcPointerHandlerActive, "qt.quick.handler.active")
Q_DECLARE_LOGGING_CATEGORY(lcHandlerParent)
 
QQuickPointerHandler::QQuickPointerHandler(QQuickItem *parent)
  : QQuickPointerHandler(*(new QQuickPointerHandlerPrivate), parent)
{
}
 
QQuickPointerHandler::QQuickPointerHandler(QQuickPointerHandlerPrivate &dd, QQuickItem *parent)
  : QObject(dd, parent)
{
    // When a handler is created in QML, the given parent is null, and we
    // depend on QQuickItemPrivate::data_append() later when it's added to an
    // item's DefaultProperty data property. But when a handler is created in
    // C++ with a parent item, data_append() won't be called, and the caller
    // shouldn't have to worry about it either.
    if (parent)
        QQuickItemPrivate::get(parent)->addPointerHandler(this);
}
 
QQuickPointerHandler::~QQuickPointerHandler()
{
    QQuickItem *parItem = parentItem();
    if (parItem) {
        QQuickItemPrivate *p = QQuickItemPrivate::get(parItem);
        p->extra.value().pointerHandlers.removeOne(this);
    }
}
 
qreal QQuickPointerHandler::margin() const
{
    Q_D(const QQuickPointerHandler);
    return d->m_margin;
}
 
void QQuickPointerHandler::setMargin(qreal pointDistanceThreshold)
{
    Q_D(QQuickPointerHandler);
    if (d->m_margin == pointDistanceThreshold)
        return;
 
    d->m_margin = pointDistanceThreshold;
    emit marginChanged();
}
 
int QQuickPointerHandler::dragThreshold() const
{
    Q_D(const QQuickPointerHandler);
    if (d->dragThreshold < 0)
        return qApp->styleHints()->startDragDistance();
    return d->dragThreshold;
}
 
void QQuickPointerHandler::setDragThreshold(int t)
{
    Q_D(QQuickPointerHandler);
    if (d->dragThreshold == t)
        return;
 
    if (t > std::numeric_limits<qint16>::max())
        qWarning() << "drag threshold cannot exceed" << std::numeric_limits<qint16>::max();
    d->dragThreshold = qint16(t);
    emit dragThresholdChanged();
}
 
void QQuickPointerHandler::resetDragThreshold()
{
    Q_D(QQuickPointerHandler);
    if (d->dragThreshold < 0)
        return;
 
    d->dragThreshold = -1;
    emit dragThresholdChanged();
}
 
#if QT_CONFIG(cursor)
Qt::CursorShape QQuickPointerHandler::cursorShape() const
{
    Q_D(const QQuickPointerHandler);
    return d->cursorShape;
}
 
void QQuickPointerHandler::setCursorShape(Qt::CursorShape shape)
{
    Q_D(QQuickPointerHandler);
    if (d->cursorSet && shape == d->cursorShape)
        return;
    d->cursorShape = shape;
    d->cursorSet = true;
    if (auto *parent = parentItem()) {
        QQuickItemPrivate *itemPriv = QQuickItemPrivate::get(parent);
        itemPriv->hasCursorHandler = true;
        itemPriv->setHasCursorInChild(true);
    }
    emit cursorShapeChanged();
}
 
void QQuickPointerHandler::resetCursorShape()
{
    Q_D(QQuickPointerHandler);
    if (!d->cursorSet)
        return;
    d->cursorShape = Qt::ArrowCursor;
    d->cursorSet = false;
    if (auto *parent = parentItem()) {
        QQuickItemPrivate *itemPriv = QQuickItemPrivate::get(parent);
        itemPriv->hasCursorHandler = false;
        itemPriv->setHasCursorInChild(itemPriv->hasCursor);
    }
    emit cursorShapeChanged();
}
 
bool QQuickPointerHandler::isCursorShapeExplicitlySet() const
{
    Q_D(const QQuickPointerHandler);
    return d->cursorSet;
}
#endif
 
void QQuickPointerHandler::onGrabChanged(QQuickPointerHandler *grabber, QPointingDevice::GrabTransition transition,
                                         QPointerEvent *event, QEventPoint &point)
{
    Q_UNUSED(event);
    qCDebug(lcPointerHandlerGrab) << point << transition << grabber;
    if (grabber == this) {
        bool wasCanceled = false;
        switch (transition) {
        case QPointingDevice::GrabPassive:
        case QPointingDevice::GrabExclusive:
            break;
        case QPointingDevice::CancelGrabPassive:
        case QPointingDevice::CancelGrabExclusive:
            wasCanceled = true; // the grab was stolen by something else
            Q_FALLTHROUGH();
        case QPointingDevice::UngrabPassive:
        case QPointingDevice::UngrabExclusive:
            setActive(false);
            point.setAccepted(false);
            if (auto par = parentItem()) {
                Q_D(const QQuickPointerHandler);
                par->setKeepMouseGrab(d->hadKeepMouseGrab);
                par->setKeepTouchGrab(d->hadKeepTouchGrab);
            }
            break;
        case QPointingDevice::OverrideGrabPassive:
            // Passive grab is still there, but we won't receive point updates right now.
            // No need to notify about this.
            return;
        }
        if (wasCanceled)
            emit canceled(point);
        emit grabChanged(transition, point);
    }
}
 
void QQuickPointerHandler::setPassiveGrab(QPointerEvent *event, const QEventPoint &point, bool grab)
{
    qCDebug(lcPointerHandlerGrab) << this << point << grab << "via"
                                  << QQuickDeliveryAgentPrivate::currentOrItemDeliveryAgent(parentItem());
    if (grab) {
        event->addPassiveGrabber(point, this);
    } else {
        event->removePassiveGrabber(point, this);
    }
}
 
bool QQuickPointerHandler::canGrab(QPointerEvent *event, const QEventPoint &point)
{
    QQuickPointerHandler *existingPhGrabber = qobject_cast<QQuickPointerHandler *>(event->exclusiveGrabber(point));
    return approveGrabTransition(event, point, this) &&
        (existingPhGrabber ? existingPhGrabber->approveGrabTransition(event, point, this) : true);
}
 
bool QQuickPointerHandler::approveGrabTransition(QPointerEvent *event, const QEventPoint &point, QObject *proposedGrabber)
{
    Q_D(const QQuickPointerHandler);
    bool allowed = false;
    QObject* existingGrabber = event->exclusiveGrabber(point);
    if (proposedGrabber == this) {
        allowed = (existingGrabber == nullptr) || ((d->grabPermissions & CanTakeOverFromAnything) == CanTakeOverFromAnything);
        if (existingGrabber) {
            if (QQuickPointerHandler *existingPhGrabber = qobject_cast<QQuickPointerHandler *>(event->exclusiveGrabber(point))) {
                if (!allowed && (d->grabPermissions & CanTakeOverFromHandlersOfDifferentType) &&
                        existingPhGrabber->metaObject()->className() != metaObject()->className())
                    allowed = true;
                if (!allowed && (d->grabPermissions & CanTakeOverFromHandlersOfSameType) &&
                        existingPhGrabber->metaObject()->className() == metaObject()->className())
                    allowed = true;
            } else if ((d->grabPermissions & CanTakeOverFromItems)) {
                allowed = true;
                QQuickItem * existingItemGrabber = qobject_cast<QQuickItem *>(event->exclusiveGrabber(point));
                auto da = parentItem() ? QQuickItemPrivate::get(parentItem())->deliveryAgentPrivate()
                                       : QQuickDeliveryAgentPrivate::currentEventDeliveryAgent ? static_cast<QQuickDeliveryAgentPrivate *>(
                                            QQuickDeliveryAgentPrivate::get(QQuickDeliveryAgentPrivate::currentEventDeliveryAgent)) : nullptr;
                const bool isTouchMouse = (da && da->isDeliveringTouchAsMouse());
                if (existingItemGrabber &&
                        ((existingItemGrabber->keepMouseGrab() &&
                          (QQuickDeliveryAgentPrivate::isMouseEvent(event) || isTouchMouse)) ||
                         (existingItemGrabber->keepTouchGrab() && QQuickDeliveryAgentPrivate::isTouchEvent(event)))) {
                    allowed = false;
                    // If the handler wants to steal the exclusive grab from an Item, the Item can usually veto
                    // by having its keepMouseGrab flag set.  But an exception is if that Item is a parent that
                    // normally filters events (such as a Flickable): it needs to be possible for e.g. a
                    // DragHandler to operate on an Item inside a Flickable.  Flickable is aggressive about
                    // grabbing on press (for fear of missing updates), but DragHandler uses a passive grab
                    // at first and then expects to be able to steal the grab later on.  It cannot respect
                    // Flickable's wishes in that case, because then it would never have a chance.
                    if (existingItemGrabber->keepMouseGrab() &&
                            existingItemGrabber->filtersChildMouseEvents() && existingItemGrabber->isAncestorOf(parentItem())) {
                        Q_ASSERT(da);
                        if (isTouchMouse && point.id() == da->touchMouseId) {
                            qCDebug(lcPointerHandlerGrab) << this << "steals touchpoint" << point.id()
                                << "despite parent touch-mouse grabber with keepMouseGrab=true" << existingItemGrabber;
                            allowed = true;
                        }
                    }
                    if (!allowed) {
                        qCDebug(lcPointerHandlerGrab) << this << "wants to grab point" << point.id()
                                << "but declines to steal from grabber" << existingItemGrabber
                                << "with keepMouseGrab=" << existingItemGrabber->keepMouseGrab()
                                << "keepTouchGrab=" << existingItemGrabber->keepTouchGrab();
                    }
                }
            }
        }
    } else {
        // proposedGrabber is different: that means this instance will lose its grab
        if (proposedGrabber) {
            if ((d->grabPermissions & ApprovesTakeOverByAnything) == ApprovesTakeOverByAnything)
                allowed = true;
            if (!allowed && (d->grabPermissions & ApprovesTakeOverByHandlersOfDifferentType) &&
                    proposedGrabber->metaObject()->className() != metaObject()->className())
                allowed = true;
            if (!allowed && (d->grabPermissions & ApprovesTakeOverByHandlersOfSameType) &&
                    proposedGrabber->metaObject()->className() == metaObject()->className())
                allowed = true;
            if (!allowed && (d->grabPermissions & ApprovesTakeOverByItems) && proposedGrabber->inherits("QQuickItem"))
                allowed = true;
        } else {
            if (d->grabPermissions & ApprovesCancellation)
                allowed = true;
        }
    }
    qCDebug(lcPointerHandlerGrab) << "point" << Qt::hex << point.id() << "permission" <<
            QMetaEnum::fromType<GrabPermissions>().valueToKeys(grabPermissions()) <<
            ':' << this << (allowed ? "approved from" : "denied from") <<
            existingGrabber << "to" << proposedGrabber;
    return allowed;
}
 
QQuickPointerHandler::GrabPermissions QQuickPointerHandler::grabPermissions() const
{
    Q_D(const QQuickPointerHandler);
    return static_cast<QQuickPointerHandler::GrabPermissions>(d->grabPermissions);
}
 
void QQuickPointerHandler::setGrabPermissions(GrabPermissions grabPermission)
{
    Q_D(QQuickPointerHandler);
    if (d->grabPermissions == grabPermission)
        return;
 
    d->grabPermissions = grabPermission;
    emit grabPermissionChanged();
}
 
void QQuickPointerHandler::classBegin()
{
}
 
void QQuickPointerHandler::componentComplete()
{
    Q_D(const QQuickPointerHandler);
    if (d->cursorSet) {
        if (auto *parent = parentItem()) {
            QQuickItemPrivate *itemPriv = QQuickItemPrivate::get(parent);
            itemPriv->hasCursorHandler = true;
            itemPriv->setHasCursorInChild(true);
        }
    }
}
 
QPointerEvent *QQuickPointerHandler::currentEvent()
{
    Q_D(const QQuickPointerHandler);
    return d->currentEvent;
}
 
bool QQuickPointerHandler::setExclusiveGrab(QPointerEvent *ev, const QEventPoint &point, bool grab)
{
    if ((grab && ev->exclusiveGrabber(point) == this) || (!grab && ev->exclusiveGrabber(point) != this))
        return true;
    // TODO m_hadKeepMouseGrab m_hadKeepTouchGrab
    bool allowed = true;
    if (grab) {
        allowed = canGrab(ev, point);
    } else {
        QQuickPointerHandler *existingPhGrabber = qobject_cast<QQuickPointerHandler *>(ev->exclusiveGrabber(point));
        // Ask before allowing one handler to cancel another's grab
        if (existingPhGrabber && existingPhGrabber != this && !existingPhGrabber->approveGrabTransition(ev, point, nullptr))
            allowed = false;
    }
    qCDebug(lcPointerHandlerGrab) << point << (grab ? "grab" : "ungrab") << (allowed ? "allowed" : "forbidden") <<
        ev->exclusiveGrabber(point) << "->" << (grab ? this : nullptr);
    if (allowed)
        ev->setExclusiveGrabber(point, grab ? this : nullptr);
    return allowed;
}
 
void QQuickPointerHandler::cancelAllGrabs(QPointerEvent *event, QEventPoint &point)
{
    qCDebug(lcPointerHandlerGrab) << point;
    if (event->exclusiveGrabber(point) == this) {
        event->setExclusiveGrabber(point, nullptr);
        onGrabChanged(this, QPointingDevice::CancelGrabExclusive, event, point);
    }
    if (event->removePassiveGrabber(point, this))
        onGrabChanged(this, QPointingDevice::CancelGrabPassive, event, point);
}
 
QPointF QQuickPointerHandler::eventPos(const QEventPoint &point) const
{
    return (target() ? target()->mapFromScene(point.scenePosition()) : point.scenePosition());
}
 
bool QQuickPointerHandler::parentContains(const QEventPoint &point) const
{
    return parentContains(point.scenePosition());
}
 
bool QQuickPointerHandler::parentContains(const QPointF &scenePosition) const
{
    if (QQuickItem *par = parentItem()) {
        if (par->window()) {
            QRect windowGeometry = par->window()->geometry();
            if (!par->window()->isTopLevel())
                windowGeometry = QRect(QWindowPrivate::get(par->window())->globalPosition(), par->window()->size());
            QPoint screenPosition = par->window()->mapToGlobal(scenePosition.toPoint());
            if (!windowGeometry.contains(screenPosition))
                return false;
        }
        QPointF p = par->mapFromScene(scenePosition);
        qreal m = margin();
        if (m > 0)
            return p.x() >= -m && p.y() >= -m && p.x() <= par->width() + m && p.y() <= par->height() + m;
        return par->contains(p);
    } else if (parent() && parent()->inherits("QQuick3DModel")) {
        // If the parent is from Qt Quick 3D, assume that
        // bounds checking was already done, as part of picking.
        return true;
    }
    return false;
}
 
bool QQuickPointerHandler::enabled() const
{
    Q_D(const QQuickPointerHandler);
    return d->enabled;
}
 
void QQuickPointerHandler::setEnabled(bool enabled)
{
    Q_D(QQuickPointerHandler);
    if (d->enabled == enabled)
        return;
 
    d->enabled = enabled;
    d->onEnabledChanged();
 
    emit enabledChanged();
}
 
QQuickItem *QQuickPointerHandler::target() const
{
    Q_D(const QQuickPointerHandler);
    if (!d->targetExplicitlySet)
        return parentItem();
    return d->target;
}
 
void QQuickPointerHandler::setTarget(QQuickItem *target)
{
    Q_D(QQuickPointerHandler);
    d->targetExplicitlySet = true;
    if (d->target == target)
        return;
 
    QQuickItem *oldTarget = d->target;
    d->target = target;
    onTargetChanged(oldTarget);
    emit targetChanged();
}
 
QQuickItem *QQuickPointerHandler::parentItem() const
{
    return qmlobject_cast<QQuickItem *>(QObject::parent());
}
 
void QQuickPointerHandler::setParentItem(QQuickItem *p)
{
    Q_D(QQuickPointerHandler);
    if (QObject::parent() == p)
        return;
 
    qCDebug(lcHandlerParent) << "reparenting handler" << this << ":" << parent() << "->" << p;
    auto *oldParent = static_cast<QQuickItem *>(QObject::parent());
    if (oldParent)
        QQuickItemPrivate::get(oldParent)->removePointerHandler(this);
    setParent(p);
    if (p)
        QQuickItemPrivate::get(p)->addPointerHandler(this);
    d->onParentChanged(oldParent, p);
    emit parentChanged();
}
 
bool QQuickPointerHandler::event(QEvent *e)
{
    switch (e->type()) {
    case QEvent::TouchCancel: {
        auto te = static_cast<QTouchEvent *>(e);
        for (int i = 0; i < te->pointCount(); ++i)
            onGrabChanged(this, QPointingDevice::CancelGrabExclusive, te, te->point(i));
        return true;
        break;
    }
    default:
        return QObject::event(e);
        break;
    }
}
 
void QQuickPointerHandler::handlePointerEvent(QPointerEvent *event)
{
    Q_D(QQuickPointerHandler);
    bool wants = wantsPointerEvent(event);
    qCDebug(lcPointerHandlerDispatch) << metaObject()->className() << objectName()
                                      << "on" << parent()->metaObject()->className() << parent()->objectName()
                                      << (wants ? "WANTS" : "DECLINES") << event;
    d->currentEvent = event;
    if (wants) {
        handlePointerEventImpl(event);
        d->lastEventTime = event->timestamp();
    } else {
#if QT_CONFIG(gestures)
        if (event->type() != QEvent::NativeGesture)
#endif
            setActive(false);
        for (int i = 0; i < event->pointCount(); ++i) {
            auto &pt = event->point(i);
            if (event->exclusiveGrabber(pt) == this && pt.state() != QEventPoint::Stationary)
                event->setExclusiveGrabber(pt, nullptr);
        }
    }
    d->currentEvent = nullptr;
    QQuickPointerHandlerPrivate::deviceDeliveryTargets(event->device()).append(this);
}
 
bool QQuickPointerHandler::wantsPointerEvent(QPointerEvent *event)
{
    Q_D(const QQuickPointerHandler);
    Q_UNUSED(event);
    return d->enabled;
}
 
bool QQuickPointerHandler::wantsEventPoint(const QPointerEvent *event, const QEventPoint &point)
{
    Q_UNUSED(event);
    bool ret = event->exclusiveGrabber(point) == this ||
            event->passiveGrabbers(point).contains(this) || parentContains(point);
    qCDebug(lcPointerHandlerDispatch) << Qt::hex << point.id() << "@" << point.scenePosition()
                                      << metaObject()->className() << objectName() << ret;
    return ret;
}
 
bool QQuickPointerHandler::active() const
{
    Q_D(const QQuickPointerHandler);
    return d->active;
}
 
void QQuickPointerHandler::setActive(bool active)
{
    Q_D(QQuickPointerHandler);
    if (d->active != active) {
        qCDebug(lcPointerHandlerActive) << this << d->active << "->" << active;
        d->active = active;
        onActiveChanged();
        emit activeChanged();
    }
}
 
void QQuickPointerHandler::handlePointerEventImpl(QPointerEvent *event)
{
    Q_UNUSED(event);
}
 
QQuickPointerHandlerPrivate::QQuickPointerHandlerPrivate()
  : grabPermissions(QQuickPointerHandler::CanTakeOverFromItems |
                      QQuickPointerHandler::CanTakeOverFromHandlersOfDifferentType |
                      QQuickPointerHandler::ApprovesTakeOverByAnything)
  , cursorShape(Qt::ArrowCursor)
  , enabled(true)
  , active(false)
  , targetExplicitlySet(false)
  , hadKeepMouseGrab(false)
  , hadKeepTouchGrab(false)
  , cursorSet(false)
{
}
 
template <typename TEventPoint>
bool QQuickPointerHandlerPrivate::dragOverThreshold(qreal d, Qt::Axis axis, const TEventPoint &p) const
{
    Q_Q(const QQuickPointerHandler);
    QStyleHints *styleHints = qApp->styleHints();
    bool overThreshold = qAbs(d) > q->dragThreshold();
    const bool dragVelocityLimitAvailable = (styleHints->startDragVelocity() > 0);
    if (!overThreshold && dragVelocityLimitAvailable) {
        qreal velocity = qreal(axis == Qt::XAxis ? p.velocity().x() : p.velocity().y());
        overThreshold |= qAbs(velocity) > styleHints->startDragVelocity();
    }
    return overThreshold;
}
 
bool QQuickPointerHandlerPrivate::dragOverThreshold(QVector2D delta) const
{
    Q_Q(const QQuickPointerHandler);
    const float threshold = q->dragThreshold();
    return qAbs(delta.x()) > threshold || qAbs(delta.y()) > threshold;
}
 
bool QQuickPointerHandlerPrivate::dragOverThreshold(const QEventPoint &point) const
{
    QPointF delta = point.scenePosition() - point.scenePressPosition();
    return (dragOverThreshold(delta.x(), Qt::XAxis, point) ||
            dragOverThreshold(delta.y(), Qt::YAxis, point));
}
 
QVector<QObject *> &QQuickPointerHandlerPrivate::deviceDeliveryTargets(const QInputDevice *device)
{
    return QQuickDeliveryAgentPrivate::deviceExtra(device)->deliveryTargets;
}
 
QT_END_NAMESPACE
 
#include "moc_qquickpointerhandler_p.cpp"