path: root/src/declarative/util/qdeclarativeconnections.cpp

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#include "private/qdeclarativeconnections_p.h"

#include <qdeclarativeexpression.h>
#include <qdeclarativeproperty_p.h>
#include <qdeclarativeboundsignal_p.h>
#include <qdeclarativecontext.h>
#include <qdeclarativeinfo.h>

#include <QtCore/qdebug.h>
#include <QtCore/qstringlist.h>

#include <private/qobject_p.h>

QT_BEGIN_NAMESPACE

class QDeclarativeConnectionsPrivate : public QObjectPrivate
{
public:
    QDeclarativeConnectionsPrivate() : target(0), targetSet(false), ignoreUnknownSignals(false), componentcomplete(true) {}

    QList<QDeclarativeBoundSignal*> boundsignals;
    QObject *target;

    bool targetSet;
    bool ignoreUnknownSignals;
    bool componentcomplete;

    QByteArray data;
};

/*!
    \qmlclass Connections QDeclarativeConnections
  \since 4.7
    \brief A Connections object describes generalized connections to signals.

    When connecting to signals in QML, the usual way is to create an
    "on<Signal>" handler that reacts when a signal is received, like this:

    \qml
    MouseArea {
        onClicked: { foo(...) }
    }
    \endqml

    However, in some cases, it is not possible to connect to a signal in this
    way, such as:

    \list
        \i multiple connections to the same signal
        \i connections outside the scope of the signal sender
        \i connections to targets not defined in QML
    \endlist

    When any of these are needed, the Connections object can be used instead.

    For example, the above code can be changed to use a Connections object,
    like this:

    \qml
    MouseArea {
        Connections {
            onClicked: foo(...)
        }
    }
    \endqml

    More generally, the Connections object can be a child of some other object than
    the sender of the signal:

    \qml
    MouseArea {
        id: area
    }
    ...
    Connections {
        target: area
        onClicked: foo(...)
    }
    \endqml

    \sa QtDeclarative
*/

/*!
    \internal
    \class QDeclarativeConnections
    \brief The QDeclarativeConnections class describes generalized connections to signals.

*/
QDeclarativeConnections::QDeclarativeConnections(QObject *parent) :
    QObject(*(new QDeclarativeConnectionsPrivate), parent)
{
}

QDeclarativeConnections::~QDeclarativeConnections()
{
}

/*!
    \qmlproperty Object Connections::target
    This property holds the object that sends the signal.

    If not set at all, the target defaults to be the parent of the Connections.

    If set to null, no connection is made and any signal handlers are ignored
    until the target is not null.
*/
QObject *QDeclarativeConnections::target() const
{
    Q_D(const QDeclarativeConnections);
    return d->targetSet ? d->target : parent();
}

void QDeclarativeConnections::setTarget(QObject *obj)
{
    Q_D(QDeclarativeConnections);
    d->targetSet = true; // even if setting to 0, it is *set*
    if (d->target == obj)
        return;
    foreach (QDeclarativeBoundSignal *s, d->boundsignals) {
        // It is possible that target is being changed due to one of our signal
        // handlers -> use deleteLater().
        if (s->isEvaluating())
            s->deleteLater();
        else
            delete s;
    }
    d->boundsignals.clear();
    d->target = obj;
    connectSignals();
    emit targetChanged();
}

/*!
    \qmlproperty bool Connections::ignoreUnknownSignals

    Normally, you will get a runtime error if you try to connect
    to signals on an object which the object does not have.

    By setting this flag to true, such errors are ignored. This is
    useful if you intend to connect to different types of object, handling
    a different set of signals for each.
*/
bool QDeclarativeConnections::ignoreUnknownSignals() const
{
    Q_D(const QDeclarativeConnections);
    return d->ignoreUnknownSignals;
}

void QDeclarativeConnections::setIgnoreUnknownSignals(bool ignore)
{
    Q_D(QDeclarativeConnections);
    d->ignoreUnknownSignals = ignore;
}



QByteArray
QDeclarativeConnectionsParser::compile(const QList<QDeclarativeCustomParserProperty> &props)
{
    QByteArray rv;
    QDataStream ds(&rv, QIODevice::WriteOnly);

    for(int ii = 0; ii < props.count(); ++ii)
    {
        QString propName = QString::fromUtf8(props.at(ii).name());
        if (!propName.startsWith(QLatin1String("on")) || !propName.at(2).isUpper()) {
            error(props.at(ii), QDeclarativeConnections::tr("Cannot assign to non-existent property \"%1\"").arg(propName));
            return QByteArray();
        }

        QList<QVariant> values = props.at(ii).assignedValues();

        for (int i = 0; i < values.count(); ++i) {
            const QVariant &value = values.at(i);

            if (value.userType() == qMetaTypeId<QDeclarativeCustomParserNode>()) {
                error(props.at(ii), QDeclarativeConnections::tr("Connections: nested objects not allowed"));
                return QByteArray();
            } else if (value.userType() == qMetaTypeId<QDeclarativeCustomParserProperty>()) {
                error(props.at(ii), QDeclarativeConnections::tr("Connections: syntax error"));
                return QByteArray();
            } else {
                QDeclarativeParser::Variant v = qvariant_cast<QDeclarativeParser::Variant>(value);
                if (v.isScript()) {
                    ds << propName;
                    ds << v.asScript();
                } else {
                    error(props.at(ii), QDeclarativeConnections::tr("Connections: script expected"));
                    return QByteArray();
                }
            }
        }
    }

    return rv;
}

void QDeclarativeConnectionsParser::setCustomData(QObject *object,
                                            const QByteArray &data)
{
    QDeclarativeConnectionsPrivate *p =
        static_cast<QDeclarativeConnectionsPrivate *>(QObjectPrivate::get(object));
    p->data = data;
}


void QDeclarativeConnections::connectSignals()
{
    Q_D(QDeclarativeConnections);
    if (!d->componentcomplete || (d->targetSet && !target()))
        return;

    QDataStream ds(d->data);
    while (!ds.atEnd()) {
        QString propName;
        ds >> propName;
        QString script;
        ds >> script;
        QDeclarativeProperty prop(target(), propName);
        if (prop.isValid() && (prop.type() & QDeclarativeProperty::SignalProperty)) {
            QDeclarativeBoundSignal *signal =
                new QDeclarativeBoundSignal(target(), prop.method(), this);
            signal->setExpression(new QDeclarativeExpression(qmlContext(this), script, 0));
            d->boundsignals += signal;
        } else {
            if (!d->ignoreUnknownSignals)
                qmlInfo(this) << tr("Cannot assign to non-existent property \"%1\"").arg(propName);
        }
    }
}

void QDeclarativeConnections::classBegin()
{
    Q_D(QDeclarativeConnections);
    d->componentcomplete=false;
}

void QDeclarativeConnections::componentComplete()
{
    Q_D(QDeclarativeConnections);
    d->componentcomplete=true;
    connectSignals();
}

QT_END_NAMESPACE