qquickpinchhandler.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 "qquickpinchhandler_p.h"
#include <QtQml/qqmlinfo.h>
#include <QtQuick/qquickwindow.h>
#include <private/qsgadaptationlayer_p.h>
#include <private/qquickitem_p.h>
#include <private/qguiapplication_p.h>
#include <private/qquickmultipointhandler_p_p.h>
#include <private/qquickwindow_p.h>
#include <QEvent>
#include <QMouseEvent>
#include <QDebug>
#include <qpa/qplatformnativeinterface.h>
#include <math.h>
 
QT_BEGIN_NAMESPACE
 
Q_LOGGING_CATEGORY(lcPinchHandler, "qt.quick.handler.pinch")
 
 
QQuickPinchHandler::QQuickPinchHandler(QQuickItem *parent)
    : QQuickMultiPointHandler(parent, 2)
{
    // Tell QQuickPointerDeviceHandler::wantsPointerEvent() to ignore button state
    d_func()->acceptedButtons = Qt::NoButton;
}
 
#if QT_DEPRECATED_SINCE(6, 5)
void QQuickPinchHandler::setMinimumScale(qreal minimumScale)
{
    if (qFuzzyCompare(m_scaleAxis.minimum(), minimumScale))
        return;
 
    m_scaleAxis.setMinimum(minimumScale);
    emit minimumScaleChanged();
}
 
void QQuickPinchHandler::setMaximumScale(qreal maximumScale)
{
    if (qFuzzyCompare(m_scaleAxis.maximum(), maximumScale))
        return;
 
    m_scaleAxis.setMaximum(maximumScale);
    emit maximumScaleChanged();
}
#endif
 
void QQuickPinchHandler::setActiveScale(qreal scale)
{
    if (scale == activeScale())
        return;
 
    qreal delta = scale / m_scaleAxis.activeValue();
    m_scaleAxis.updateValue(scale, m_scaleAxis.m_startValue * scale, delta);
    emit scaleChanged(delta);
}
 
void QQuickPinchHandler::setPersistentScale(qreal scale)
{
    if (scale == persistentScale())
        return;
 
    m_scaleAxis.updateValue(m_scaleAxis.activeValue(), scale);
    emit scaleChanged(1);
}
 
#if QT_DEPRECATED_SINCE(6, 5)
void QQuickPinchHandler::setMinimumRotation(qreal minimumRotation)
{
    if (qFuzzyCompare(m_rotationAxis.minimum(), minimumRotation))
        return;
 
    m_rotationAxis.setMinimum(minimumRotation);
    emit minimumRotationChanged();
}
 
void QQuickPinchHandler::setMaximumRotation(qreal maximumRotation)
{
    if (qFuzzyCompare(m_rotationAxis.maximum(), maximumRotation))
        return;
 
    m_rotationAxis.setMaximum(maximumRotation);
    emit maximumRotationChanged();
}
#endif
 
void QQuickPinchHandler::setActiveRotation(qreal rot)
{
    if (rot == activeRotation())
        return;
 
    qreal delta = rot - m_rotationAxis.activeValue();
    m_rotationAxis.updateValue(rot, m_rotationAxis.m_startValue + rot, delta);
    emit rotationChanged(delta);
}
 
void QQuickPinchHandler::setPersistentRotation(qreal rot)
{
    if (rot == persistentRotation())
        return;
 
    m_rotationAxis.updateValue(m_rotationAxis.activeValue(), rot);
    emit rotationChanged(0);
}
 
void QQuickPinchHandler::setPersistentTranslation(const QPointF &trans)
{
    if (trans == persistentTranslation())
        return;
 
    m_xAxis.updateValue(m_xAxis.activeValue(), trans.x());
    m_yAxis.updateValue(m_yAxis.activeValue(), trans.y());
    emit translationChanged({});
}
 
bool QQuickPinchHandler::wantsPointerEvent(QPointerEvent *event)
{
    if (!QQuickMultiPointHandler::wantsPointerEvent(event))
        return false;
 
#if QT_CONFIG(gestures)
    if (event->type() == QEvent::NativeGesture) {
        const auto gesture = static_cast<const QNativeGestureEvent *>(event);
        if (!gesture->fingerCount() || (gesture->fingerCount() >= minimumPointCount() &&
                                        gesture->fingerCount() <= maximumPointCount())) {
            switch (gesture->gestureType()) {
            case Qt::BeginNativeGesture:
            case Qt::EndNativeGesture:
            case Qt::ZoomNativeGesture:
            case Qt::RotateNativeGesture:
                return parentContains(event->point(0));
            default:
                return false;
            }
        } else {
            return false;
        }
    }
#endif
 
    return true;
}
 
void QQuickPinchHandler::onActiveChanged()
{
    QQuickMultiPointHandler::onActiveChanged();
    const bool curActive = active();
    m_xAxis.onActiveChanged(curActive, 0);
    m_yAxis.onActiveChanged(curActive, 0);
    m_scaleAxis.onActiveChanged(curActive, 1);
    m_rotationAxis.onActiveChanged(curActive, 0);
 
    if (curActive) {
        m_startAngles = angles(centroid().sceneGrabPosition());
        m_startDistance = averageTouchPointDistance(centroid().sceneGrabPosition());
        m_startTargetPos = target() ? target()->position() : QPointF();
        qCDebug(lcPinchHandler) << "activated with starting scale" << m_scaleAxis.m_startValue
                                << "rotation" << m_rotationAxis.m_startValue
                                << "target pos" << m_startTargetPos;
    } else {
        m_startTargetPos = QPointF();
        qCDebug(lcPinchHandler) << "deactivated with scale" << m_scaleAxis.m_activeValue << "rotation" << m_rotationAxis.m_activeValue;
    }
}
 
void QQuickPinchHandler::handlePointerEventImpl(QPointerEvent *event)
{
    QQuickMultiPointHandler::handlePointerEventImpl(event);
    if (Q_UNLIKELY(lcPinchHandler().isDebugEnabled())) {
        for (const QQuickHandlerPoint &p : currentPoints())
            qCDebug(lcPinchHandler) << Qt::hex << p.id() << p.sceneGrabPosition() << "->" << p.scenePosition();
    }
 
    qreal dist = 0;
#if QT_CONFIG(gestures)
    if (event->type() == QEvent::NativeGesture) {
        const auto gesture = static_cast<const QNativeGestureEvent *>(event);
        mutableCentroid().reset(event, event->point(0));
        switch (gesture->gestureType()) {
        case Qt::BeginNativeGesture:
            setActive(true);
            // Native gestures for 2-finger pinch do not allow dragging, so
            // the centroid won't move during the gesture, and translation stays at zero
            return;
        case Qt::EndNativeGesture:
            mutableCentroid().reset();
            setActive(false);
            emit updated();
            return;
        case Qt::ZoomNativeGesture:
            setActiveScale(m_scaleAxis.activeValue() * (1 + gesture->value()));
            break;
        case Qt::RotateNativeGesture:
            setActiveRotation(m_rotationAxis.activeValue() + gesture->value());
            break;
        default:
            // Nothing of interest (which is unexpected, because wantsPointerEvent() should have returned false)
            return;
        }
    } else
#endif // QT_CONFIG(gestures)
    {
        const bool containsReleasedPoints = event->isEndEvent();
        QVector<QEventPoint> chosenPoints;
        for (const QQuickHandlerPoint &p : currentPoints()) {
            auto ep = event->pointById(p.id());
            Q_ASSERT(ep);
            chosenPoints << *ep;
        }
        if (!active()) {
            // Verify that at least one of the points has moved beyond threshold needed to activate the handler
            int numberOfPointsDraggedOverThreshold = 0;
            QVector2D accumulatedDrag;
            const QVector2D currentCentroid(centroid().scenePosition());
            const QVector2D pressCentroid(centroid().scenePressPosition());
 
            const int dragThreshold = QQuickPointerHandler::dragThreshold();
            const int dragThresholdSquared = dragThreshold * dragThreshold;
 
            double accumulatedCentroidDistance = 0;     // Used to detect scale
            if (event->isBeginEvent())
                m_accumulatedStartCentroidDistance = 0;   // Used to detect scale
 
            float accumulatedMovementMagnitude = 0;
 
            for (auto &point : chosenPoints) {
                if (!containsReleasedPoints) {
                    accumulatedDrag += QVector2D(point.scenePressPosition() - point.scenePosition());
                    /*
                       In order to detect a drag, we want to check if all points have moved more or
                       less in the same direction.
 
                       We then take each point, and convert the point to a local coordinate system where
                       the centroid is the origin. This is done both for the press positions and the
                       current positions. We will then have two positions:
 
                       - pressCentroidRelativePosition
                           is the start point relative to the press centroid
                       - currentCentroidRelativePosition
                           is the current point relative to the current centroid
 
                       If those two points are far enough apart, it might not be considered as a drag
                       anymore. (Note that the threshold will matched to the average of the relative
                       movement of all the points). Therefore, a big relative movement will make a big
                       contribution to the average relative movement.
 
                       The algorithm then can be described as:
                         For each point:
                          - Calculate vector pressCentroidRelativePosition (from the press centroid to the press position)
                          - Calculate vector currentCentroidRelativePosition (from the current centroid to the current position)
                          - Calculate the relative movement vector:
 
                             centroidRelativeMovement = currentCentroidRelativePosition - pressCentroidRelativePosition
 
                           and measure its magnitude. Add the magnitude to the accumulatedMovementMagnitude.
 
                         Finally, if the accumulatedMovementMagnitude is below some threshold, it means
                         that the points were stationary or they were moved in parallel (e.g. the hand
                         was moved, but the relative position between each finger remained very much
                         the same). This is then used to rule out if there is a rotation or scale.
                    */
                    QVector2D pressCentroidRelativePosition = QVector2D(point.scenePosition()) - currentCentroid;
                    QVector2D currentCentroidRelativePosition = QVector2D(point.scenePressPosition()) - pressCentroid;
                    QVector2D centroidRelativeMovement = currentCentroidRelativePosition - pressCentroidRelativePosition;
                    accumulatedMovementMagnitude += centroidRelativeMovement.length();
 
                    accumulatedCentroidDistance += qreal(pressCentroidRelativePosition.length());
                    if (event->isBeginEvent())
                        m_accumulatedStartCentroidDistance += qreal((QVector2D(point.scenePressPosition()) - pressCentroid).length());
                } else {
                    setPassiveGrab(event, point);
                }
                if (point.state() == QEventPoint::Pressed) {
                    point.setAccepted(false); // don't stop propagation
                    setPassiveGrab(event, point);
                }
                Q_D(QQuickMultiPointHandler);
                if (d->dragOverThreshold(point))
                    ++numberOfPointsDraggedOverThreshold;
            }
 
            const bool requiredNumberOfPointsDraggedOverThreshold =
                    numberOfPointsDraggedOverThreshold >= minimumPointCount() &&
                    numberOfPointsDraggedOverThreshold <= maximumPointCount();
            accumulatedMovementMagnitude /= currentPoints().size();
 
            QVector2D avgDrag = accumulatedDrag / currentPoints().size();
            if (!xAxis()->enabled())
                avgDrag.setX(0);
            if (!yAxis()->enabled())
                avgDrag.setY(0);
 
            const qreal centroidMovementDelta = qreal((currentCentroid - pressCentroid).length());
 
            qreal distanceToCentroidDelta = qAbs(accumulatedCentroidDistance - m_accumulatedStartCentroidDistance); // Used to detect scale
            if (numberOfPointsDraggedOverThreshold >= 1) {
                if (requiredNumberOfPointsDraggedOverThreshold &&
                        avgDrag.lengthSquared() >= dragThresholdSquared && accumulatedMovementMagnitude < dragThreshold) {
                    // Drag
                    if (grabPoints(event, chosenPoints))
                        setActive(true);
                } else if (distanceToCentroidDelta > dragThreshold) {    // all points should in accumulation have been moved beyond threshold (?)
                    // Scale
                    if (grabPoints(event, chosenPoints))
                        setActive(true);
                } else if (distanceToCentroidDelta < dragThreshold && (centroidMovementDelta < dragThreshold)) {
                    // Rotate
                    // Since it wasn't a scale and if we exceeded the dragthreshold, and the
                    // centroid didn't moved much, the points must have been moved around the centroid.
                    if (grabPoints(event, chosenPoints))
                        setActive(true);
                }
            }
            if (!active())
                return;
        }
 
        // avoid mapping the minima and maxima, as they might have unmappable values
        // such as -inf/+inf. Because of this we perform the bounding to min/max in local coords.
        // 1. scale
        qreal activeScale = 1;
        if (m_scaleAxis.enabled()) {
            dist = averageTouchPointDistance(centroid().scenePosition());
            activeScale = dist / m_startDistance;
            activeScale = qBound(m_scaleAxis.minimum() / m_scaleAxis.m_startValue, activeScale,
                                 m_scaleAxis.maximum() / m_scaleAxis.m_startValue);
            setActiveScale(activeScale);
        }
 
        // 2. rotate
        if (m_rotationAxis.enabled()) {
            QVector<PointData> newAngles = angles(centroid().scenePosition());
            const qreal angleDelta = averageAngleDelta(m_startAngles, newAngles);
            setActiveRotation(m_rotationAxis.m_activeValue + angleDelta);
            m_startAngles = std::move(newAngles);
        }
 
        if (!containsReleasedPoints)
            acceptPoints(chosenPoints);
    }
 
 
    if (target() && target()->parentItem()) {
        auto *t = target();
        const QPointF centroidParentPos = t->parentItem()->mapFromScene(centroid().scenePosition());
        // 3. Drag/translate
        const QPointF centroidStartParentPos = t->parentItem()->mapFromScene(centroid().sceneGrabPosition());
        auto activeTranslation = centroidParentPos - centroidStartParentPos;
        // apply rotation + scaling around the centroid - then apply translation.
        QPointF pos = QQuickItemPrivate::get(t)->adjustedPosForTransform(centroidParentPos,
                m_startTargetPos, QVector2D(activeTranslation),
                t->scale(), m_scaleAxis.persistentValue() / m_scaleAxis.m_startValue,
                t->rotation(), m_rotationAxis.persistentValue() - m_rotationAxis.m_startValue);
 
        if (xAxis()->enabled())
            pos.setX(qBound(xAxis()->minimum(), pos.x(), xAxis()->maximum()));
        else
            pos.rx() -= qreal(activeTranslation.x());
        if (yAxis()->enabled())
            pos.setY(qBound(yAxis()->minimum(), pos.y(), yAxis()->maximum()));
        else
            pos.ry() -= qreal(activeTranslation.y());
 
        const QVector2D delta(activeTranslation.x() - m_xAxis.activeValue(),
                              activeTranslation.y() - m_yAxis.activeValue());
        m_xAxis.updateValue(activeTranslation.x(), m_xAxis.persistentValue() + delta.x(), delta.x());
        m_yAxis.updateValue(activeTranslation.y(), m_yAxis.persistentValue() + delta.y(), delta.y());
        emit translationChanged(delta);
        t->setPosition(pos);
        t->setRotation(m_rotationAxis.persistentValue());
        t->setScale(m_scaleAxis.persistentValue());
    } else {
        auto activeTranslation = centroid().scenePosition() - centroid().scenePressPosition();
        auto accumulated = QPointF(m_xAxis.m_startValue, m_yAxis.m_startValue) + activeTranslation;
        const QVector2D delta(activeTranslation.x() - m_xAxis.activeValue(),
                              activeTranslation.y() - m_yAxis.activeValue());
        m_xAxis.updateValue(activeTranslation.x(), accumulated.x(), delta.x());
        m_yAxis.updateValue(activeTranslation.y(), accumulated.y(), delta.y());
        emit translationChanged(delta);
    }
 
    qCDebug(lcPinchHandler) << "centroid" << centroid().scenePressPosition() << "->"  << centroid().scenePosition()
                            << ", distance" << m_startDistance << "->" << dist
                            << ", scale" << m_scaleAxis.m_startValue << "->" << m_scaleAxis.m_accumulatedValue
                            << ", rotation" << m_rotationAxis.m_startValue << "->" << m_rotationAxis.m_accumulatedValue
                            << ", translation" << persistentTranslation()
                            << " from " << event->device()->type();
 
    emit updated();
}
 
QT_END_NAMESPACE
 
#include "moc_qquickpinchhandler_p.cpp"