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

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#include "qmlpropertychanges_p.h"

#include "qmlopenmetaobject_p.h"

#include <qmlinfo.h>
#include <qmlcustomparser_p.h>
#include <qmlparser_p.h>
#include <qmlexpression.h>
#include <qmlbinding.h>
#include <qmlcontext.h>
#include <qmlguard_p.h>

#include <QtCore/qdebug.h>

#include <private/qobject_p.h>

QT_BEGIN_NAMESPACE

/*!
    \qmlclass PropertyChanges QmlPropertyChanges
    \brief The PropertyChanges element describes new property values for a state.

    PropertyChanges provides a state change that modifies the properties of an item.

    Here is a property change that modifies the text and color of a Text element
    when it is clicked:
    
    \qml
    Text {
        id: myText
        width: 100; height: 100
        text: "Hello"
        color: "blue"

        states: State {
            name: "myState"

            PropertyChanges {
                target: myText
                text: "Goodbye"
                color: "red"
            }
        }

        MouseRegion { anchors.fill: parent; onClicked: myText.state = 'myState' }
    }
    \endqml
    
    State-specific script for signal handlers can also be specified:

    \qml
    PropertyChanges {
        target: myMouseRegion
        onClicked: doSomethingDifferent()
    }
    \endqml

    Changes to an Item's parent or anchors should be done using the associated change elements
    (ParentChange and AnchorChanges, respectively) rather than PropertyChanges.

    \sa {qmlstate}{States}
*/

/*!
    \internal
    \class QmlPropertyChanges
    \brief The QmlPropertyChanges class describes new property values for a state.
*/

/*!
    \qmlproperty Object PropertyChanges::target
    This property holds the object which contains the properties to be changed.
*/

class QmlReplaceSignalHandler : public QmlActionEvent
{
public:
    QmlReplaceSignalHandler() : expression(0), reverseExpression(0),
                                rewindExpression(0), ownedExpression(0) {}
    ~QmlReplaceSignalHandler() {
        delete ownedExpression;
    }

    virtual QString typeName() const { return QLatin1String("ReplaceSignalHandler"); }

    QmlMetaProperty property;
    QmlExpression *expression;
    QmlExpression *reverseExpression;
    QmlExpression *rewindExpression;
    QmlGuard<QmlExpression> ownedExpression;

    virtual void execute() {
        ownedExpression = property.setSignalExpression(expression);
    }

    virtual bool isReversable() { return true; }
    virtual void reverse() {
        ownedExpression = property.setSignalExpression(reverseExpression);
    }

    virtual void saveOriginals() {
        saveCurrentValues();
        reverseExpression = rewindExpression;
    }

    virtual void rewind() {
        ownedExpression = property.setSignalExpression(rewindExpression);
    }
    virtual void saveCurrentValues() { rewindExpression = property.signalExpression(); }

    virtual bool override(QmlActionEvent*other) {
        if (other == this)
            return true;
        if (other->typeName() != typeName())
            return false;
        if (static_cast<QmlReplaceSignalHandler*>(other)->property == property)
            return true;
        return false;
    }
};


class QmlPropertyChangesPrivate : public QObjectPrivate
{
    Q_DECLARE_PUBLIC(QmlPropertyChanges)
public:
    QmlPropertyChangesPrivate() : object(0), decoded(true), restore(true),
                                isExplicit(false) {}

    QObject *object;
    QByteArray data;

    bool decoded : 1;
    bool restore : 1;
    bool isExplicit : 1;

    void decode();

    QList<QPair<QByteArray, QVariant> > properties;
    QList<QPair<QByteArray, QmlExpression *> > expressions;
    QList<QmlReplaceSignalHandler*> signalReplacements;

    QmlMetaProperty property(const QByteArray &);
};

class QmlPropertyChangesParser : public QmlCustomParser
{
public:
    void compileList(QList<QPair<QByteArray, QVariant> > &list, const QByteArray &pre, const QmlCustomParserProperty &prop);

    virtual QByteArray compile(const QList<QmlCustomParserProperty> &);
    virtual void setCustomData(QObject *, const QByteArray &);
};

void
QmlPropertyChangesParser::compileList(QList<QPair<QByteArray, QVariant> > &list,
                                     const QByteArray &pre,
                                     const QmlCustomParserProperty &prop)
{
    QByteArray propName = pre + prop.name();

    QList<QVariant> values = prop.assignedValues();
    for (int ii = 0; ii < values.count(); ++ii) {
        const QVariant &value = values.at(ii);

        if (value.userType() == qMetaTypeId<QmlCustomParserNode>()) {
            continue;
        } else if(value.userType() == qMetaTypeId<QmlCustomParserProperty>()) {

            QmlCustomParserProperty prop =
                qvariant_cast<QmlCustomParserProperty>(value);
            QByteArray pre = propName + '.';
            compileList(list, pre, prop);

        } else {
            list << qMakePair(propName, value);
        }
    }
}

QByteArray
QmlPropertyChangesParser::compile(const QList<QmlCustomParserProperty> &props)
{
    QList<QPair<QByteArray, QVariant> > data;
    for(int ii = 0; ii < props.count(); ++ii)
        compileList(data, QByteArray(), props.at(ii));

    QByteArray rv;
    QDataStream ds(&rv, QIODevice::WriteOnly);

    ds << data.count();
    for(int ii = 0; ii < data.count(); ++ii) {
        QmlParser::Variant v = qvariant_cast<QmlParser::Variant>(data.at(ii).second);
        QVariant var;
        bool isScript = v.isScript();
        switch(v.type()) {
        case QmlParser::Variant::Boolean:
            var = QVariant(v.asBoolean());
            break;
        case QmlParser::Variant::Number:
            var = QVariant(v.asNumber());
            break;
        case QmlParser::Variant::String:
            var = QVariant(v.asString());
            break;
        case QmlParser::Variant::Invalid:
        case QmlParser::Variant::Script:
            var = QVariant(v.asScript());
            break;
        }

        ds << data.at(ii).first << isScript << var;
    }

    return rv;
}

void QmlPropertyChangesPrivate::decode()
{
    Q_Q(QmlPropertyChanges);
    if (decoded)
        return;

    QDataStream ds(&data, QIODevice::ReadOnly);

    int count;
    ds >> count;
    for (int ii = 0; ii < count; ++ii) {
        QByteArray name;
        bool isScript;
        QVariant data;
        ds >> name;
        ds >> isScript;
        ds >> data;

        QmlMetaProperty prop = property(name);      //### better way to check for signal property?
        if (prop.type() & QmlMetaProperty::SignalProperty) {
            QmlExpression *expression = new QmlExpression(qmlContext(q), data.toString(), object);
            expression->setTrackChange(false);
            QmlReplaceSignalHandler *handler = new QmlReplaceSignalHandler;
            handler->property = prop;
            handler->expression = expression;
            signalReplacements << handler;
        } else if (isScript) {
            QmlExpression *expression = new QmlExpression(qmlContext(q), data.toString(), object);
            expression->setTrackChange(false);
            expressions << qMakePair(name, expression);
        } else {
            properties << qMakePair(name, data);
        }
    }

    decoded = true;
    data.clear();
}

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

QmlPropertyChanges::QmlPropertyChanges()
: QmlStateOperation(*(new QmlPropertyChangesPrivate))
{
}

QmlPropertyChanges::~QmlPropertyChanges()
{
    Q_D(QmlPropertyChanges);
    for(int ii = 0; ii < d->expressions.count(); ++ii)
        delete d->expressions.at(ii).second;
    for(int ii = 0; ii < d->signalReplacements.count(); ++ii)
        delete d->signalReplacements.at(ii);
}

QObject *QmlPropertyChanges::object() const
{
    Q_D(const QmlPropertyChanges);
    return d->object;
}

void QmlPropertyChanges::setObject(QObject *o)
{
    Q_D(QmlPropertyChanges);
    d->object = o;
}

/*!
    \qmlproperty bool PropertyChanges::restoreEntryValues
    
    Whether or not the previous values should be restored when
    leaving the state. By default, restoreEntryValues is true.

    By setting restoreEntryValues to false, you can create a temporary state
    that has permanent effects on property values.
*/
bool QmlPropertyChanges::restoreEntryValues() const
{
    Q_D(const QmlPropertyChanges);
    return d->restore;
}

void QmlPropertyChanges::setRestoreEntryValues(bool v)
{
    Q_D(QmlPropertyChanges);
    d->restore = v;
}

QmlMetaProperty
QmlPropertyChangesPrivate::property(const QByteArray &property)
{
    Q_Q(QmlPropertyChanges);
    QmlMetaProperty prop = QmlMetaProperty::createProperty(object, QString::fromUtf8(property));
    if (!prop.isValid()) {
        qmlInfo(q) << QmlPropertyChanges::tr("Cannot assign to non-existant property \"%1\"").arg(QString::fromUtf8(property));
        return QmlMetaProperty();
    } else if (!(prop.type() & QmlMetaProperty::SignalProperty) && !prop.isWritable()) {
        qmlInfo(q) << QmlPropertyChanges::tr("Cannot assign to read-only property \"%1\"").arg(QString::fromUtf8(property));
        return QmlMetaProperty();
    }
    return prop;
}

QmlPropertyChanges::ActionList QmlPropertyChanges::actions()
{
    Q_D(QmlPropertyChanges);

    d->decode();

    ActionList list;

    for (int ii = 0; ii < d->properties.count(); ++ii) {

        QByteArray property = d->properties.at(ii).first;

        QmlAction a(d->object, QString::fromLatin1(property),
                 d->properties.at(ii).second);

        if (a.property.isValid()) {
            a.restore = restoreEntryValues();

            if (a.property.propertyType() == QVariant::Url &&
                (a.toValue.userType() == QVariant::String || a.toValue.userType() == QVariant::ByteArray) && !a.toValue.isNull())
                a.toValue.setValue(qmlContext(this)->resolvedUrl(QUrl(a.toValue.toString())));

            list << a;
        }
    }

    for (int ii = 0; ii < d->signalReplacements.count(); ++ii) {

        QmlReplaceSignalHandler *handler = d->signalReplacements.at(ii);

        if (handler->property.isValid()) {
            QmlAction a;
            a.event = handler;
            list << a;
        }
    }

    for (int ii = 0; ii < d->expressions.count(); ++ii) {

        QByteArray property = d->expressions.at(ii).first;
        QmlMetaProperty prop = d->property(property);

        if (prop.isValid()) {
            QmlAction a;
            a.restore = restoreEntryValues();
            a.property = prop;
            a.fromValue = a.property.read();
            a.specifiedObject = d->object;
            a.specifiedProperty = QString::fromLatin1(property);

            if (d->isExplicit) {
                a.toValue = d->expressions.at(ii).second->value();
            } else {
                QmlBinding *newBinding = new QmlBinding(d->expressions.at(ii).second->expression(), object(), qmlContext(this));
                newBinding->setTarget(prop);
                a.toBinding = newBinding;
                a.deletableToBinding = true;
            }

            list << a;
        }
    }

    return list;
}

/*!
    \qmlproperty bool PropertyChanges::explicit

    If explicit is set to true, any potential bindings will be interpreted as
    once-off assignments that occur when the state is entered.

    In the following example, the addition of explicit prevents myItem.width from
    being bound to parent.width. Instead, it is assigned the value of parent.width
    at the time of the state change.
    \qml
    PropertyChanges {
        target: myItem
        explicit: true
        width: parent.width
    }
    \endqml

    By default, explicit is false.
*/
bool QmlPropertyChanges::isExplicit() const
{
    Q_D(const QmlPropertyChanges);
    return d->isExplicit;
}

void QmlPropertyChanges::setIsExplicit(bool e)
{
    Q_D(QmlPropertyChanges);
    d->isExplicit = e;
}

QML_DEFINE_CUSTOM_TYPE(Qt, 4,6, PropertyChanges, QmlPropertyChanges, QmlPropertyChangesParser)

QT_END_NAMESPACE