qquickdrag.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 "qquickdrag_p.h"
#include "qquickdrag_p_p.h"
 
#include <private/qguiapplication_p.h>
#include <qpa/qplatformintegration.h>
#include <private/qquickitem_p.h>
#include <QtQuick/private/qquickevents_p_p.h>
#include <private/qquickitemchangelistener_p.h>
#include <private/qquickpixmap_p.h>
#include <private/qv4scopedvalue_p.h>
#include <QtCore/qbuffer.h>
#include <QtCore/qmimedata.h>
#include <QtCore/qstringconverter.h>
#include <QtQml/qqmlinfo.h>
#include <QtGui/qevent.h>
#include <QtGui/qstylehints.h>
#include <QtGui/qguiapplication.h>
#include <QtGui/qimagewriter.h>
 
#include <qpa/qplatformdrag.h>
#include <QtGui/qdrag.h>
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
 
 
void QQuickDragAttachedPrivate::itemGeometryChanged(QQuickItem *, QQuickGeometryChange change,
                                                    const QRectF &)
{
    if (!change.positionChange() || !active || itemMoved)
        return;
    updatePosition();
}
 
void QQuickDragAttachedPrivate::itemParentChanged(QQuickItem *, QQuickItem *)
{
    if (!active || dragRestarted)
        return;
 
    QQuickWindow *newWindow = attachedItem->window();
 
    if (window != newWindow)
        restartDrag();
    else if (window)
        updatePosition();
}
 
void QQuickDragAttachedPrivate::updatePosition()
{
    Q_Q(QQuickDragAttached);
    itemMoved = true;
    if (!eventQueued) {
        eventQueued = true;
        QCoreApplication::postEvent(q, new QEvent(QEvent::User));
    }
}
 
void QQuickDragAttachedPrivate::restartDrag()
{
    Q_Q(QQuickDragAttached);
    dragRestarted = true;
    if (!eventQueued) {
        eventQueued = true;
        QCoreApplication::postEvent(q, new QEvent(QEvent::User));
    }
}
 
void QQuickDragAttachedPrivate::deliverEnterEvent()
{
    dragRestarted = false;
    itemMoved = false;
 
    window = attachedItem->window();
 
    mimeData->m_source = source;
    if (!overrideActions)
        mimeData->m_supportedActions = supportedActions;
    mimeData->m_keys = keys;
 
    if (window) {
        QPoint scenePos = attachedItem->mapToScene(hotSpot).toPoint();
        QDragEnterEvent event(scenePos, mimeData->m_supportedActions, mimeData, Qt::NoButton, Qt::NoModifier);
        QQuickDropEventEx::setProposedAction(&event, proposedAction);
        deliverEvent(window, &event);
    }
}
 
void QQuickDragAttachedPrivate::deliverMoveEvent()
{
    Q_Q(QQuickDragAttached);
 
    itemMoved = false;
    if (window) {
        QPoint scenePos = attachedItem->mapToScene(hotSpot).toPoint();
        QDragMoveEvent event(scenePos, mimeData->m_supportedActions, mimeData, Qt::NoButton, Qt::NoModifier);
        QQuickDropEventEx::setProposedAction(&event, proposedAction);
        deliverEvent(window, &event);
        if (target != dragGrabber.target()) {
            target = dragGrabber.target();
            emit q->targetChanged();
        }
    }
}
 
void QQuickDragAttachedPrivate::deliverLeaveEvent()
{
    if (window) {
        QDragLeaveEvent event;
        deliverEvent(window, &event);
        window = nullptr;
    }
}
 
void QQuickDragAttachedPrivate::deliverEvent(QQuickWindow *window, QEvent *event)
{
    Q_ASSERT(!inEvent);
    inEvent = true;
    QQuickWindowPrivate::get(window)->deliveryAgentPrivate()->deliverDragEvent(&dragGrabber, event);
    inEvent = false;
}
 
bool QQuickDragAttached::event(QEvent *event)
{
    Q_D(QQuickDragAttached);
 
    if (event->type() == QEvent::User) {
        d->eventQueued = false;
        if (d->dragRestarted) {
            d->deliverLeaveEvent();
            if (!d->mimeData)
                d->mimeData = new QQuickDragMimeData;
            d->deliverEnterEvent();
 
            if (d->target != d->dragGrabber.target()) {
                d->target = d->dragGrabber.target();
                emit targetChanged();
            }
        } else if (d->itemMoved) {
            d->deliverMoveEvent();
        }
        return true;
    } else {
        return QObject::event(event);
    }
}
 
QQuickDragAttached::QQuickDragAttached(QObject *parent)
    : QObject(*new QQuickDragAttachedPrivate, parent)
{
    Q_D(QQuickDragAttached);
    d->attachedItem = qobject_cast<QQuickItem *>(parent);
    d->source = d->attachedItem;
}
 
QQuickDragAttached::~QQuickDragAttached()
{
    Q_D(QQuickDragAttached);
    delete d->mimeData;
}
 
bool QQuickDragAttached::isActive() const
{
    Q_D(const QQuickDragAttached);
    return d->active;
}
 
void QQuickDragAttached::setActive(bool active)
{
    Q_D(QQuickDragAttached);
    if (d->active != active) {
        if (d->inEvent)
            qmlWarning(this) << "active cannot be changed from within a drag event handler";
        else if (active) {
            if (d->dragType == QQuickDrag::Internal) {
                d->start(d->supportedActions);
            } else {
                d->active = true;
                emit activeChanged();
                if (d->dragType == QQuickDrag::Automatic) {
                    // There are different semantics than start() since startDrag()
                    // may be called after an internal drag is already started.
                    d->startDrag(d->supportedActions);
                }
            }
        }
        else
            cancel();
    }
}
 
QObject *QQuickDragAttached::source() const
{
    Q_D(const QQuickDragAttached);
    return d->source;
}
 
void QQuickDragAttached::setSource(QObject *item)
{
    Q_D(QQuickDragAttached);
    if (d->source != item) {
        d->source = item;
        if (d->active)
            d->restartDrag();
        emit sourceChanged();
    }
}
 
void QQuickDragAttached::resetSource()
{
    Q_D(QQuickDragAttached);
    if (d->source != d->attachedItem) {
        d->source = d->attachedItem;
        if (d->active)
            d->restartDrag();
        emit sourceChanged();
    }
}
 
QObject *QQuickDragAttached::target() const
{
    Q_D(const QQuickDragAttached);
    return d->target;
}
 
QPointF QQuickDragAttached::hotSpot() const
{
    Q_D(const QQuickDragAttached);
    return d->hotSpot;
}
 
void QQuickDragAttached::setHotSpot(const QPointF &hotSpot)
{
    Q_D(QQuickDragAttached);
    if (d->hotSpot != hotSpot) {
        d->hotSpot = hotSpot;
 
        if (d->active)
            d->updatePosition();
 
        emit hotSpotChanged();
    }
}
 
QUrl QQuickDragAttached::imageSource() const
{
    Q_D(const QQuickDragAttached);
    return d->imageSource;
}
 
void QQuickDragAttached::setImageSource(const QUrl &url)
{
    Q_D(QQuickDragAttached);
    if (d->imageSource != url) {
        d->imageSource = url;
 
        if (url.isEmpty()) {
            d->pixmapLoader.clear();
        } else {
            d->loadPixmap();
        }
 
        Q_EMIT imageSourceChanged();
    }
}
 
QSize QQuickDragAttached::imageSourceSize() const
{
    Q_D(const QQuickDragAttached);
    int width = d->imageSourceSize.width();
    int height = d->imageSourceSize.height();
    return QSize(width != -1 ? width : d->pixmapLoader.width(),
                 height != -1 ? height : d->pixmapLoader.height());
}
 
void QQuickDragAttached::setImageSourceSize(const QSize &size)
{
    Q_D(QQuickDragAttached);
    if (d->imageSourceSize != size) {
        d->imageSourceSize = size;
 
        if (!d->imageSource.isEmpty())
            d->loadPixmap();
 
        Q_EMIT imageSourceSizeChanged();
    }
}
 
QStringList QQuickDragAttached::keys() const
{
    Q_D(const QQuickDragAttached);
    return d->keys;
}
 
void QQuickDragAttached::setKeys(const QStringList &keys)
{
    Q_D(QQuickDragAttached);
    if (d->keys != keys) {
        d->keys = keys;
        if (d->active)
            d->restartDrag();
        emit keysChanged();
    }
}
 
QVariantMap QQuickDragAttached::mimeData() const
{
    Q_D(const QQuickDragAttached);
    return d->externalMimeData;
}
 
void QQuickDragAttached::setMimeData(const QVariantMap &mimeData)
{
    Q_D(QQuickDragAttached);
    if (d->externalMimeData != mimeData) {
        d->externalMimeData = mimeData;
        emit mimeDataChanged();
    }
}
 
Qt::DropActions QQuickDragAttached::supportedActions() const
{
    Q_D(const QQuickDragAttached);
    return d->supportedActions;
}
 
void QQuickDragAttached::setSupportedActions(Qt::DropActions actions)
{
    Q_D(QQuickDragAttached);
    if (d->supportedActions != actions) {
        d->supportedActions = actions;
        if (d->active)
            d->restartDrag();
        emit supportedActionsChanged();
    }
}
 
Qt::DropAction QQuickDragAttached::proposedAction() const
{
    Q_D(const QQuickDragAttached);
    return d->proposedAction;
}
 
void QQuickDragAttached::setProposedAction(Qt::DropAction action)
{
    Q_D(QQuickDragAttached);
    if (d->proposedAction != action) {
        d->proposedAction = action;
        // The proposed action shouldn't affect whether a drag is accepted
        // so leave/enter events are excessive, but the target should still
        // updated.
        if (d->active)
            d->updatePosition();
        emit proposedActionChanged();
    }
}
 
QQuickDrag::DragType QQuickDragAttached::dragType() const
{
    Q_D(const QQuickDragAttached);
    return d->dragType;
}
 
void QQuickDragAttached::setDragType(QQuickDrag::DragType dragType)
{
    Q_D(QQuickDragAttached);
    if (d->dragType != dragType) {
        d->dragType = dragType;
        emit dragTypeChanged();
    }
}
 
void QQuickDragAttachedPrivate::start(Qt::DropActions supportedActions)
{
    Q_Q(QQuickDragAttached);
    Q_ASSERT(!active);
 
    if (!mimeData)
        mimeData = new QQuickDragMimeData;
    if (!listening) {
        QQuickItemPrivate::get(attachedItem)->addItemChangeListener(
                this, QQuickItemPrivate::Geometry | QQuickItemPrivate::Parent);
        listening = true;
    }
 
    mimeData->m_supportedActions = supportedActions;
    active = true;
    itemMoved = false;
    dragRestarted = false;
 
    deliverEnterEvent();
 
    if (target != dragGrabber.target()) {
        target = dragGrabber.target();
        emit q->targetChanged();
    }
 
    emit q->activeChanged();
}
 
void QQuickDragAttached::start(QQmlV4FunctionPtr args)
{
    Q_D(QQuickDragAttached);
    if (d->inEvent) {
        qmlWarning(this) << "start() cannot be called from within a drag event handler";
        return;
    }
 
    if (d->active)
        cancel();
 
    d->overrideActions = false;
    Qt::DropActions supportedActions = d->supportedActions;
    // check arguments for supportedActions, maybe data?
    if (args->length() >= 1) {
        QV4::Scope scope(args->v4engine());
        QV4::ScopedValue v(scope, (*args)[0]);
        if (v->isInt32()) {
            supportedActions = Qt::DropActions(v->integerValue());
            d->overrideActions = true;
        }
    }
 
    d->start(supportedActions);
}
 
int QQuickDragAttached::drop()
{
    Q_D(QQuickDragAttached);
    Qt::DropAction acceptedAction = Qt::IgnoreAction;
 
    if (d->inEvent) {
        qmlWarning(this) << "drop() cannot be called from within a drag event handler";
        return acceptedAction;
    }
 
    if (d->itemMoved)
        d->deliverMoveEvent();
 
    if (!d->active)
        return acceptedAction;
    d->active = false;
 
    QObject *target = nullptr;
 
    if (d->window) {
        QPoint scenePos = d->attachedItem->mapToScene(d->hotSpot).toPoint();
 
        QDropEvent event(
                scenePos, d->mimeData->m_supportedActions, d->mimeData, Qt::NoButton, Qt::NoModifier);
        QQuickDropEventEx::setProposedAction(&event, d->proposedAction);
        d->deliverEvent(d->window, &event);
 
        if (event.isAccepted()) {
            acceptedAction = event.dropAction();
            target = d->dragGrabber.target();
        }
    }
 
    if (d->target != target) {
        d->target = target;
        emit targetChanged();
    }
 
    emit activeChanged();
    return acceptedAction;
}
 
void QQuickDragAttached::cancel()
{
    Q_D(QQuickDragAttached);
 
    if (d->inEvent) {
        qmlWarning(this) << "cancel() cannot be called from within a drag event handler";
        return;
    }
 
    if (!d->active)
        return;
    d->active = false;
    d->deliverLeaveEvent();
 
    if (d->target) {
        d->target = nullptr;
        emit targetChanged();
    }
 
    emit activeChanged();
}
 
QMimeData *QQuickDragAttachedPrivate::createMimeData() const
{
    Q_Q(const QQuickDragAttached);
    QMimeData *mimeData = new QMimeData();
 
    for (const auto [mimeType, value] : externalMimeData.asKeyValueRange()) {
        switch (value.typeId()) {
        case QMetaType::QByteArray:
            // byte array assumed to already be correctly encoded
            mimeData->setData(mimeType, value.toByteArray());
            break;
        case QMetaType::QString: {
            const QString text = value.toString();
            if (mimeType == u"text/plain"_s) {
                mimeData->setText(text);
            } else if (mimeType == u"text/html"_s) {
                mimeData->setHtml(text);
            } else if (mimeType == u"text/uri-list"_s) {
                const QUrl url(text);
                if (url.isValid())
                    mimeData->setUrls({url});
                else
                    qmlWarning(q) << text << " is not a valid URI";
            } else if (mimeType.startsWith(u"text/"_s)) {
                if (qsizetype charsetIdx = mimeType.lastIndexOf(u";charset="_s); charsetIdx != -1) {
                    charsetIdx += sizeof(";charset=") - 1;
                    const QByteArray encoding = mimeType.mid(charsetIdx).toUtf8();
                    QStringEncoder encoder(encoding);
                    if (encoder.isValid())
                        mimeData->setData(mimeType, encoder.encode(text));
                    else
                        qmlWarning(q) << "Don't know how to encode text as " << mimeType;
                } else {
                    mimeData->setData(mimeType, text.toUtf8());
                }
            } else {
                mimeData->setData(mimeType, text.toUtf8());
            }
            break;
        }
        case QMetaType::QVariantList:
        case QMetaType::QStringList:
            if (mimeType == u"text/uri-list"_s) {
                const QVariantList values = value.toList();
                QList<QUrl> urls;
                urls.reserve(values.size());
                bool error = false;
                for (qsizetype index = 0; index < values.size(); ++index) {
                    const QUrl url = values.at(index).value<QUrl>();
                    if (url.isValid()) {
                        urls += url;
                    } else {
                        error = true;
                        qmlWarning(q) << "Value '" << values.at(index) << "' at index " << index
                                      << " is not a valid URI";
                    }
                }
                if (!error)
                    mimeData->setUrls(urls);
            }
            break;
        case QMetaType::QImage:
            if (const QByteArray mimeTypeUtf8 = mimeType.toUtf8();
                QImageWriter::supportedMimeTypes().contains(mimeTypeUtf8)) {
                const auto imageFormats = QImageWriter::imageFormatsForMimeType(mimeTypeUtf8);
                if (imageFormats.isEmpty()) { // shouldn't happen, but we can fall back
                    mimeData->setImageData(value);
                    break;
                }
                const QImage image = value.value<QImage>();
                QByteArray bytes;
                {
                    QBuffer buffer(&bytes);
                    QImageWriter encoder(&buffer, imageFormats.first());
                    encoder.write(image);
                }
                mimeData->setData(mimeType, bytes);
                break;
            }
            Q_FALLTHROUGH();
        default:
            qmlWarning(q) << "Don't know how to encode variant of type " << value.metaType()
                          << " as mime type " << mimeType;
            // compatibility with pre-6.5 - probably a bad idea
            mimeData->setData(mimeType, value.toString().toUtf8());
            break;
        }
    }
 
    return mimeData;
}
 
void QQuickDragAttachedPrivate::loadPixmap()
{
    Q_Q(QQuickDragAttached);
 
    QUrl loadUrl = imageSource;
    const QQmlContext *context = qmlContext(q->parent());
    if (context)
        loadUrl = context->resolvedUrl(imageSource);
    pixmapLoader.load(context ? context->engine() : nullptr, loadUrl, QRect(), q->imageSourceSize());
}
 
Qt::DropAction QQuickDragAttachedPrivate::startDrag(Qt::DropActions supportedActions)
{
    Q_Q(QQuickDragAttached);
 
    QDrag *drag = new QDrag(source ? source : q);
 
    drag->setMimeData(createMimeData());
    if (pixmapLoader.isReady())
        drag->setPixmap(QPixmap::fromImage(pixmapLoader.image()));
 
    drag->setHotSpot(hotSpot.toPoint());
    emit q->dragStarted();
 
    Qt::DropAction dropAction = drag->exec(supportedActions);
 
    if (!QGuiApplicationPrivate::platformIntegration()->drag()->ownsDragObject())
        drag->deleteLater();
 
    deliverLeaveEvent();
 
    if (target) {
        target = nullptr;
        emit q->targetChanged();
    }
 
    emit q->dragFinished(dropAction);
 
    active = false;
    emit q->activeChanged();
 
    return dropAction;
}
 
 
void QQuickDragAttached::startDrag(QQmlV4FunctionPtr args)
{
    Q_D(QQuickDragAttached);
 
    if (d->inEvent) {
        qmlWarning(this) << "startDrag() cannot be called from within a drag event handler";
        return;
    }
 
    if (!d->active) {
        qmlWarning(this) << "startDrag() drag must be active";
        return;
    }
 
    Qt::DropActions supportedActions = d->supportedActions;
 
    // check arguments for supportedActions
    if (args->length() >= 1) {
        QV4::Scope scope(args->v4engine());
        QV4::ScopedValue v(scope, (*args)[0]);
        if (v->isInt32()) {
            supportedActions = Qt::DropActions(v->integerValue());
        }
    }
 
    Qt::DropAction dropAction = d->startDrag(supportedActions);
 
    args->setReturnValue(QV4::Encode((int)dropAction));
}
 
QQuickDrag::QQuickDrag(QObject *parent)
: QObject(parent), _target(nullptr), _axis(XAndYAxis), _xmin(-FLT_MAX),
_xmax(FLT_MAX), _ymin(-FLT_MAX), _ymax(FLT_MAX), _active(false), _filterChildren(false),
  _smoothed(true), _threshold(QGuiApplication::styleHints()->startDragDistance())
{
}
 
QQuickDrag::~QQuickDrag()
{
}
 
QQuickItem *QQuickDrag::target() const
{
    return _target;
}
 
void QQuickDrag::setTarget(QQuickItem *t)
{
    if (_target == t)
        return;
    _target = t;
    emit targetChanged();
}
 
void QQuickDrag::resetTarget()
{
    if (_target == nullptr)
        return;
    _target = nullptr;
    emit targetChanged();
}
 
QQuickDrag::Axis QQuickDrag::axis() const
{
    return _axis;
}
 
void QQuickDrag::setAxis(QQuickDrag::Axis a)
{
    if (_axis == a)
        return;
    _axis = a;
    emit axisChanged();
}
 
qreal QQuickDrag::xmin() const
{
    return _xmin;
}
 
void QQuickDrag::setXmin(qreal m)
{
    if (_xmin == m)
        return;
    _xmin = m;
    emit minimumXChanged();
}
 
qreal QQuickDrag::xmax() const
{
    return _xmax;
}
 
void QQuickDrag::setXmax(qreal m)
{
    if (_xmax == m)
        return;
    _xmax = m;
    emit maximumXChanged();
}
 
qreal QQuickDrag::ymin() const
{
    return _ymin;
}
 
void QQuickDrag::setYmin(qreal m)
{
    if (_ymin == m)
        return;
    _ymin = m;
    emit minimumYChanged();
}
 
qreal QQuickDrag::ymax() const
{
    return _ymax;
}
 
void QQuickDrag::setYmax(qreal m)
{
    if (_ymax == m)
        return;
    _ymax = m;
    emit maximumYChanged();
}
 
bool QQuickDrag::smoothed() const
{
    return _smoothed;
}
 
void QQuickDrag::setSmoothed(bool smooth)
{
    if (_smoothed != smooth) {
        _smoothed = smooth;
        emit smoothedChanged();
    }
}
 
qreal QQuickDrag::threshold() const
{
    return _threshold;
}
 
void QQuickDrag::setThreshold(qreal value)
{
    if (_threshold != value) {
        _threshold = value;
        emit thresholdChanged();
    }
}
 
void QQuickDrag::resetThreshold()
{
    setThreshold(QGuiApplication::styleHints()->startDragDistance());
}
 
bool QQuickDrag::active() const
{
    return _active;
}
 
void QQuickDrag::setActive(bool drag)
{
    if (_active == drag)
        return;
    _active = drag;
    emit activeChanged();
}
 
bool QQuickDrag::filterChildren() const
{
    return _filterChildren;
}
 
void QQuickDrag::setFilterChildren(bool filter)
{
    if (_filterChildren == filter)
        return;
    _filterChildren = filter;
    emit filterChildrenChanged();
}
 
QQuickDragAttached *QQuickDrag::qmlAttachedProperties(QObject *obj)
{
    return new QQuickDragAttached(obj);
}
 
QT_END_NAMESPACE
 
#include "moc_qquickdrag_p.cpp"