Make QmlPropertyValueSource an interface.

1st step in animation class heirarchy redesign.

15 files changed, 70 insertions, 82 deletions

diff --git a/src/declarative/extra/qmlbehaviour.cpp b/src/declarative/extra/qmlbehaviour.cpp
index 767f1ed..5401b0d 100644
--- a/src/declarative/extra/qmlbehaviour.cpp
+++ b/src/declarative/extra/qmlbehaviour.cpp
@@ -122,7 +122,7 @@ public:
 */
 
 QmlBehaviour::QmlBehaviour(QObject *parent)
-: QmlPropertyValueSource(*(new QmlBehaviourPrivate), parent)
+: QObject(*(new QmlBehaviourPrivate), parent)
 {
     Q_D(QmlBehaviour);
     d->group = new QParallelAnimationGroup;
diff --git a/src/declarative/extra/qmlbehaviour.h b/src/declarative/extra/qmlbehaviour.h
index 99fc779..b33d72a 100644
--- a/src/declarative/extra/qmlbehaviour.h
+++ b/src/declarative/extra/qmlbehaviour.h
@@ -54,7 +54,7 @@ QT_MODULE(Declarative)
 
 class QmlAbstractAnimation;
 class QmlBehaviourPrivate;
-class Q_DECLARATIVE_EXPORT QmlBehaviour : public QmlPropertyValueSource
+class Q_DECLARATIVE_EXPORT QmlBehaviour : public QObject, public QmlPropertyValueSource
 {
     Q_OBJECT
     Q_DECLARE_PRIVATE(QmlBehaviour)
diff --git a/src/declarative/qml/qml.h b/src/declarative/qml/qml.h
index bced8f2..23f2f1e 100644
--- a/src/declarative/qml/qml.h
+++ b/src/declarative/qml/qml.h
@@ -50,6 +50,7 @@
 #include <QtDeclarative/qmlmetatype.h>
 #include <QtDeclarative/qmlmetaproperty.h>
 #include <QtDeclarative/qmlparserstatus.h>
+#include <QtDeclarative/qmlpropertyvaluesource.h>
 #include <QtDeclarative/qmllist.h>
 
 QT_BEGIN_HEADER
diff --git a/src/declarative/qml/qmlcompiler.cpp b/src/declarative/qml/qmlcompiler.cpp
index bbcc64d..3af7137 100644
--- a/src/declarative/qml/qmlcompiler.cpp
+++ b/src/declarative/qml/qmlcompiler.cpp
@@ -1411,7 +1411,6 @@ void QmlCompiler::genPropertyAssignment(QmlParser::Property *prop,
 
             }
         } else if (v->type == Value::ValueSource) {
-
             genObject(v->object);
 
             QmlInstruction store;
@@ -1425,6 +1424,8 @@ void QmlCompiler::genPropertyAssignment(QmlParser::Property *prop,
                     QmlMetaPropertyPrivate::saveProperty(prop->index);
                 store.assignValueSource.owner = 0;
             }
+            QmlType *valueType = QmlMetaType::qmlType(v->object->metatype);
+            store.assignValueSource.castValue = valueType->propertyValueSourceCast();
             output->bytecode << store;
 
         } else if (v->type == Value::PropertyBinding) {
@@ -1584,15 +1585,7 @@ bool QmlCompiler::buildValueTypeProperty(QObject *type,
         Value *value = prop->values.at(0);
 
         if (value->object) {
-            const QMetaObject *c =
-                output->types.at(value->object->type).metaObject();
-            bool isPropertyValue = false;
-            while (c && !isPropertyValue) {
-                isPropertyValue =
-                    (c == &QmlPropertyValueSource::staticMetaObject);
-                c = c->superClass();
-            }
-
+            bool isPropertyValue = output->types.at(value->object->type).type->propertyValueSourceCast() != -1;
             if (!isPropertyValue) {
                 COMPILE_EXCEPTION(prop, "Invalid property use");
             } else {
@@ -1762,30 +1755,26 @@ bool QmlCompiler::buildPropertyObjectAssignment(QmlParser::Property *prop,
         v->object->metatype = output->types.at(v->object->type).metaObject();
         Q_ASSERT(v->object->metaObject());
 
+        // Will be true if the assigned type inherits QmlPropertyValueSource
+        bool isPropertyValue = false;
+        if (QmlType *valueType = QmlMetaType::qmlType(v->object->metatype))
+            isPropertyValue = valueType->propertyValueSourceCast() != -1;
+
         // We want to raw metaObject here as the raw metaobject is the
         // actual property type before we applied any extensions that might
         // effect the properties on the type, but don't effect assignability
         const QMetaObject *propertyMetaObject =
             QmlMetaType::rawMetaObjectForType(prop->type);
 
-        // Will be true if the assigned type inherits QmlPropertyValueSource
-        bool isPropertyValue = false;
         // Will be true if the assgned type inherits propertyMetaObject
         bool isAssignable = false;
-        // Determine isPropertyValue and isAssignable values
+        // Determine isAssignable value
         if (propertyMetaObject) {
             const QMetaObject *c = v->object->metatype;
             while(c) {
-                isPropertyValue |= (c == &QmlPropertyValueSource::staticMetaObject);
                 isAssignable |= (c == propertyMetaObject);
                 c = c->superClass();
             }
-        } else {
-            const QMetaObject *c = v->object->metatype;
-            while(!isPropertyValue && c) {
-                isPropertyValue |= (c == &QmlPropertyValueSource::staticMetaObject);
-                c = c->superClass();
-            }
         }
 
         if (isAssignable) {
diff --git a/src/declarative/qml/qmlinstruction.cpp b/src/declarative/qml/qmlinstruction.cpp
index 02e4883..b71c6e3 100644
--- a/src/declarative/qml/qmlinstruction.cpp
+++ b/src/declarative/qml/qmlinstruction.cpp
@@ -147,7 +147,7 @@ void QmlCompiledData::dump(QmlInstruction *instr, int idx)
         qWarning() << idx << "\t" << line << "\t" << "STORE_COMPILED_BINDING\t" << instr->assignBinding.property << "\t" << instr->assignBinding.value << "\t\t" << instr->assignBinding.context;
         break;
     case QmlInstruction::StoreValueSource:
-        qWarning() << idx << "\t" << line << "\t" << "STORE_VALUE_SOURCE\t" << instr->assignValueSource.property;
+        qWarning() << idx << "\t" << line << "\t" << "STORE_VALUE_SOURCE\t" << instr->assignValueSource.property << "\t" << instr->assignValueSource.castValue;
         break;
     case QmlInstruction::BeginObject:
         qWarning() << idx << "\t" << line << "\t" << "BEGIN\t\t\t" << instr->begin.castValue;
diff --git a/src/declarative/qml/qmlinstruction_p.h b/src/declarative/qml/qmlinstruction_p.h
index 0f2995a..8861609a 100644
--- a/src/declarative/qml/qmlinstruction_p.h
+++ b/src/declarative/qml/qmlinstruction_p.h
@@ -183,6 +183,7 @@ public:
         struct {
             int property;
             int owner;
+            int castValue;
         } assignValueSource;
         struct {
             int property;
diff --git a/src/declarative/qml/qmlmetatype.cpp b/src/declarative/qml/qmlmetatype.cpp
index ab64079..c488c13 100644
--- a/src/declarative/qml/qmlmetatype.cpp
+++ b/src/declarative/qml/qmlmetatype.cpp
@@ -120,6 +120,7 @@ public:
     QmlAttachedPropertiesFunc m_attachedPropertiesFunc;
     const QMetaObject *m_attachedPropertiesType;
     int m_parserStatusCast;
+    int m_propertyValueSourceCast;
     QmlPrivate::CreateFunc m_extFunc;
     const QMetaObject *m_extMetaObject;
     int m_index;
@@ -132,8 +133,8 @@ public:
 QmlTypePrivate::QmlTypePrivate()
 : m_isInterface(false), m_iid(0), m_typeId(0), m_listId(0), m_qmlListId(0),
   m_opFunc(0), m_baseMetaObject(0), m_attachedPropertiesFunc(0), m_attachedPropertiesType(0),
-  m_parserStatusCast(-1), m_extFunc(0), m_extMetaObject(0), m_index(-1),
-  m_customParser(0), m_isSetup(false)
+  m_parserStatusCast(-1), m_propertyValueSourceCast(-1), m_extFunc(0), m_extMetaObject(0),
+  m_index(-1), m_customParser(0), m_isSetup(false)
 {
 }
 
@@ -161,7 +162,7 @@ QmlType::QmlType(int type, int listType, int qmlListType,
                  const QMetaObject *metaObject,
                  QmlAttachedPropertiesFunc attachedPropertiesFunc,
                  const QMetaObject *attachedType,
-                 int parserStatusCast, QmlPrivate::CreateFunc extFunc,
+                 int parserStatusCast, int propertyValueSourceCast, QmlPrivate::CreateFunc extFunc,
                  const QMetaObject *extMetaObject, int index,
                  QmlCustomParser *customParser)
 : d(new QmlTypePrivate)
@@ -178,6 +179,7 @@ QmlType::QmlType(int type, int listType, int qmlListType,
     d->m_attachedPropertiesFunc = attachedPropertiesFunc;
     d->m_attachedPropertiesType = attachedType;
     d->m_parserStatusCast = parserStatusCast;
+    d->m_propertyValueSourceCast = propertyValueSourceCast;
     d->m_extFunc = extFunc;
     d->m_index = index;
     d->m_customParser = customParser;
@@ -397,6 +399,11 @@ int QmlType::parserStatusCast() const
     return d->m_parserStatusCast;
 }
 
+int QmlType::propertyValueSourceCast() const
+{
+    return d->m_propertyValueSourceCast;
+}
+
 QVariant QmlType::fromObject(QObject *obj) const
 {
     QVariant rv;
@@ -452,7 +459,7 @@ int QmlMetaType::registerInterface(const QmlPrivate::MetaTypeIds &id,
 int QmlMetaType::registerType(const QmlPrivate::MetaTypeIds &id, QmlPrivate::Func func,
         const char *uri, int version_maj, int version_min_from, int version_min_to, const char *cname,
         const QMetaObject *mo, QmlAttachedPropertiesFunc attach, const QMetaObject *attachMo,
-        int pStatus, int object, QmlPrivate::CreateFunc extFunc, const QMetaObject *extmo, QmlCustomParser *parser)
+        int pStatus, int object, int valueSource, QmlPrivate::CreateFunc extFunc, const QMetaObject *extmo, QmlCustomParser *parser)
 {
     Q_UNUSED(object);
 
@@ -476,8 +483,8 @@ int QmlMetaType::registerType(const QmlPrivate::MetaTypeIds &id, QmlPrivate::Fun
     name.replace('.','/');
 
     QmlType *type = new QmlType(id.typeId, id.listId, id.qmlListId,
-                                func, name, version_maj, version_min_from, version_min_to, mo, attach, attachMo, pStatus, extFunc,
-                                extmo, index, parser);
+                                func, name, version_maj, version_min_from, version_min_to, mo, attach, attachMo, pStatus,
+                                valueSource, extFunc, extmo, index, parser);
 
     data->types.append(type);
     data->idToType.insert(type->typeId(), type);
@@ -513,6 +520,17 @@ int QmlMetaType::qmlParserStatusCast(int userType)
         return -1;
 }
 
+int QmlMetaType::qmlPropertyValueSourceCast(int userType)
+{
+    QReadLocker lock(metaTypeDataLock());
+    QmlMetaTypeData *data = metaTypeData();
+    QmlType *type = data->idToType.value(userType);
+    if (type && type->typeId() == userType)
+        return type->propertyValueSourceCast();
+    else
+        return -1;
+}
+
 QObject *QmlMetaType::toQObject(const QVariant &v)
 {
     if (!isObject(v.userType()))
diff --git a/src/declarative/qml/qmlmetatype.h b/src/declarative/qml/qmlmetatype.h
index c388b1a..5ed9a5a 100644
--- a/src/declarative/qml/qmlmetatype.h
+++ b/src/declarative/qml/qmlmetatype.h
@@ -47,6 +47,7 @@
 #include <QtCore/qbitarray.h>
 #include <QtDeclarative/qmlprivate.h>
 #include <QtDeclarative/qmlparserstatus.h>
+#include <QtDeclarative/qmlpropertyvaluesource.h>
 
 QT_BEGIN_HEADER
 
@@ -59,7 +60,7 @@ class QmlCustomParser;
 class Q_DECLARATIVE_EXPORT QmlMetaType
 {
 public:
-    static int registerType(const QmlPrivate::MetaTypeIds &, QmlPrivate::Func, const char *, int vmaj, int vmin_from, int vmin_to, const char *qmlName, const QMetaObject *, QmlAttachedPropertiesFunc, const QMetaObject *, int pStatus, int object, QmlPrivate::CreateFunc extFunc, const QMetaObject *extmo, QmlCustomParser *);
+    static int registerType(const QmlPrivate::MetaTypeIds &, QmlPrivate::Func, const char *, int vmaj, int vmin_from, int vmin_to, const char *qmlName, const QMetaObject *, QmlAttachedPropertiesFunc, const QMetaObject *, int pStatus, int object, int valueSource, QmlPrivate::CreateFunc extFunc, const QMetaObject *extmo, QmlCustomParser *);
     static int registerInterface(const QmlPrivate::MetaTypeIds &, QmlPrivate::Func, const char *);
 
     static bool copy(int type, void *data, const void *copy = 0);
@@ -78,6 +79,7 @@ public:
     static QMetaProperty property(QObject *, const char *);
     static QObject *toQObject(const QVariant &);
     static int qmlParserStatusCast(int);
+    static int qmlPropertyValueSourceCast(int);
     static int listType(int);
     static bool clear(const QVariant &);
     static bool append(const QVariant &, const QVariant &);
@@ -143,13 +145,14 @@ public:
     int parserStatusCast() const;
     QVariant fromObject(QObject *) const;
     const char *interfaceIId() const;
+    int propertyValueSourceCast() const;
 
     int index() const;
 private:
     friend class QmlMetaType;
     friend class QmlTypePrivate;
     QmlType(int, int, int, QmlPrivate::Func, const char *, int);
-    QmlType(int, int, int, QmlPrivate::Func, const char *, int, int, int, const QMetaObject *, QmlAttachedPropertiesFunc, const QMetaObject *, int, QmlPrivate::CreateFunc, const QMetaObject *, int, QmlCustomParser *);
+    QmlType(int, int, int, QmlPrivate::Func, const char *, int, int, int, const QMetaObject *, QmlAttachedPropertiesFunc, const QMetaObject *, int, int, QmlPrivate::CreateFunc, const QMetaObject *, int, QmlCustomParser *);
     ~QmlType();
 
     QmlTypePrivate *d;
@@ -170,7 +173,8 @@ int qmlRegisterType(const char *typeName)
             QmlPrivate::attachedPropertiesFunc<T>(),
             QmlPrivate::attachedPropertiesMetaObject<T>(),
             QmlPrivate::StaticCastSelector<T,QmlParserStatus>::cast(), 
-            QmlPrivate::StaticCastSelector<T,QObject>::cast(), 
+            QmlPrivate::StaticCastSelector<T,QObject>::cast(),
+            QmlPrivate::StaticCastSelector<T,QmlPropertyValueSource>::cast(),
             0, 0, 0);
 }
 
@@ -191,6 +195,7 @@ int qmlRegisterType(const char *uri, int version_maj, int version_min_from, int
             QmlPrivate::attachedPropertiesMetaObject<T>(),
             QmlPrivate::StaticCastSelector<T,QmlParserStatus>::cast(), 
             QmlPrivate::StaticCastSelector<T,QObject>::cast(), 
+            QmlPrivate::StaticCastSelector<T,QmlPropertyValueSource>::cast(), 
             0, 0, 0);
 }
 
@@ -216,7 +221,8 @@ int qmlRegisterExtendedType(const char *typeName)
     return QmlMetaType::registerType(ids, QmlPrivate::list_nocreate_op<T>, 0, 0, 0, 0, 0,
             &T::staticMetaObject, attached, attachedMo,
             QmlPrivate::StaticCastSelector<T,QmlParserStatus>::cast(), 
-            QmlPrivate::StaticCastSelector<T,QObject>::cast(), 
+            QmlPrivate::StaticCastSelector<T,QObject>::cast(),
+            QmlPrivate::StaticCastSelector<T,QmlPropertyValueSource>::cast(),
             &QmlPrivate::CreateParent<E>::create, &E::staticMetaObject, 0);
 }
 
@@ -244,7 +250,8 @@ int qmlRegisterExtendedType(const char *uri, int version_maj, int version_min_fr
             &T::staticMetaObject,
             attached, attachedMo,
             QmlPrivate::StaticCastSelector<T,QmlParserStatus>::cast(), 
-            QmlPrivate::StaticCastSelector<T,QObject>::cast(), 
+            QmlPrivate::StaticCastSelector<T,QObject>::cast(),
+            QmlPrivate::StaticCastSelector<T,QmlPropertyValueSource>::cast(),
             &QmlPrivate::CreateParent<E>::create, 
             &E::staticMetaObject, 0);
 }
@@ -280,7 +287,8 @@ int qmlRegisterCustomType(const char *uri, int version_maj, int version_min_from
             QmlPrivate::attachedPropertiesFunc<T>(),
             QmlPrivate::attachedPropertiesMetaObject<T>(),
             QmlPrivate::StaticCastSelector<T,QmlParserStatus>::cast(), 
-            QmlPrivate::StaticCastSelector<T,QObject>::cast(), 
+            QmlPrivate::StaticCastSelector<T,QObject>::cast(),
+            QmlPrivate::StaticCastSelector<T,QmlPropertyValueSource>::cast(),
             0, 0, parser);
 }
 
diff --git a/src/declarative/qml/qmlpropertyvaluesource.cpp b/src/declarative/qml/qmlpropertyvaluesource.cpp
index c6ff596..429080b 100644
--- a/src/declarative/qml/qmlpropertyvaluesource.cpp
+++ b/src/declarative/qml/qmlpropertyvaluesource.cpp
@@ -48,34 +48,18 @@ QT_BEGIN_NAMESPACE
     \class QmlPropertyValueSource
     \brief The QmlPropertyValueSource class is inherited by property value sources such as animations and bindings.
  */
-QML_DEFINE_NOCREATE_TYPE(QmlPropertyValueSource)
 
 /*!
-    Constructs a QmlPropertyValueSource with parent \a parent.
+    Constructs a QmlPropertyValueSource.
 */
-QmlPropertyValueSource::QmlPropertyValueSource(QObject *parent)
-    : QObject(parent)
-    
-{
-}
-
-/*!
-  \internal
- */
-QmlPropertyValueSource::QmlPropertyValueSource(QObjectPrivate &dd, QObject *parent)
-    : QObject(dd, parent)
+QmlPropertyValueSource::QmlPropertyValueSource()
 {
 }
 
 /*!
+    \fn void QmlPropertyValueSource::setTarget(const QmlMetaProperty &property)
     Set the target \a property for the value source.  This method will
     be called by the QML engine when assigning a value source.
-
-    The default implementation does nothing.
 */
-void QmlPropertyValueSource::setTarget(const QmlMetaProperty &property)
-{
-    Q_UNUSED(property);
-}
 
 QT_END_NAMESPACE
diff --git a/src/declarative/qml/qmlpropertyvaluesource.h b/src/declarative/qml/qmlpropertyvaluesource.h
index 4e5f1c5..ee4ea2c 100644
--- a/src/declarative/qml/qmlpropertyvaluesource.h
+++ b/src/declarative/qml/qmlpropertyvaluesource.h
@@ -42,9 +42,7 @@
 #ifndef QMLPROPERTYVALUESOURCE_H
 #define QMLPROPERTYVALUESOURCE_H
 
-#include <QtDeclarative/qfxglobal.h>
-#include <QtDeclarative/qml.h>
-#include <QtCore/QObject>
+#include <QtCore/qobject.h>
 
 QT_BEGIN_HEADER
 
@@ -52,28 +50,17 @@ QT_BEGIN_NAMESPACE
 
 QT_MODULE(Declarative)
 
-class QObjectPrivate;
 class QmlMetaProperty;
-class Q_DECLARATIVE_EXPORT QmlPropertyValueSource : public QObject
+class Q_DECLARATIVE_EXPORT QmlPropertyValueSource
 {
-    Q_OBJECT
-    Q_DECLARE_PRIVATE(QObject)
-
 public:
-    QmlPropertyValueSource(QObject *parent);
-    virtual void setTarget(const QmlMetaProperty &);
-
-protected:
-    QmlPropertyValueSource(QObjectPrivate &dd, QObject *parent);
-
-private:
-    Q_DISABLE_COPY(QmlPropertyValueSource)
+    QmlPropertyValueSource();
+    virtual void setTarget(const QmlMetaProperty &) = 0;
 };
+Q_DECLARE_INTERFACE(QmlPropertyValueSource, "com.trolltech.qml.QmlPropertyValueSource")
 
 QT_END_NAMESPACE
 
-QML_DECLARE_TYPE(QmlPropertyValueSource)
-
 QT_END_HEADER
 
 #endif // QMLPROPERTYVALUESOURCE_H
diff --git a/src/declarative/qml/qmlvme.cpp b/src/declarative/qml/qmlvme.cpp
index 7455eb4..930e6e4 100644
--- a/src/declarative/qml/qmlvme.cpp
+++ b/src/declarative/qml/qmlvme.cpp
@@ -591,13 +591,12 @@ QObject *QmlVME::run(QStack<QObject *> &stack, QmlContext *ctxt, QmlCompiledData
 
         case QmlInstruction::StoreValueSource:
             {
-                QmlPropertyValueSource *vs = 
-                    static_cast<QmlPropertyValueSource *>(stack.pop());
-                QObject *target = 
-                    stack.at(stack.count() - 1 - instr.assignValueSource.owner);
+                QObject *obj = stack.pop();
+                QmlPropertyValueSource *vs = reinterpret_cast<QmlPropertyValueSource *>(reinterpret_cast<char *>(obj) + instr.assignValueSource.castValue);
+                QObject *target = stack.at(stack.count() - 1 - instr.assignValueSource.owner);
                 QmlMetaProperty prop;
                 prop.restore(instr.assignValueSource.property, target, ctxt);
-                vs->setParent(target);
+                obj->setParent(target);
                 vs->setTarget(prop);
             }
             break;
diff --git a/src/declarative/util/qmlanimation.cpp b/src/declarative/util/qmlanimation.cpp
index 720a045..6cc6db7 100644
--- a/src/declarative/util/qmlanimation.cpp
+++ b/src/declarative/util/qmlanimation.cpp
@@ -154,7 +154,7 @@ QML_DEFINE_NOCREATE_TYPE(QmlAbstractAnimation)
 */
 
 QmlAbstractAnimation::QmlAbstractAnimation(QObject *parent)
-: QmlPropertyValueSource(*(new QmlAbstractAnimationPrivate), parent)
+: QObject(*(new QmlAbstractAnimationPrivate), parent)
 {
 }
 
@@ -163,7 +163,7 @@ QmlAbstractAnimation::~QmlAbstractAnimation()
 }
 
 QmlAbstractAnimation::QmlAbstractAnimation(QmlAbstractAnimationPrivate &dd, QObject *parent)
-: QmlPropertyValueSource(dd, parent)
+: QObject(dd, parent)
 {
 }
 
diff --git a/src/declarative/util/qmlanimation.h b/src/declarative/util/qmlanimation.h
index f5180a5..67a2045 100644
--- a/src/declarative/util/qmlanimation.h
+++ b/src/declarative/util/qmlanimation.h
@@ -58,7 +58,7 @@ QT_MODULE(Declarative)
 
 class QmlAbstractAnimationPrivate;
 class QmlAnimationGroup;
-class QmlAbstractAnimation : public QmlPropertyValueSource, public QmlParserStatus
+class QmlAbstractAnimation : public QObject, public QmlPropertyValueSource, public QmlParserStatus
 {
     Q_OBJECT
     Q_DECLARE_PRIVATE(QmlAbstractAnimation)
diff --git a/src/declarative/util/qmlfollow.cpp b/src/declarative/util/qmlfollow.cpp
index eec2480..fe5303f 100644
--- a/src/declarative/util/qmlfollow.cpp
+++ b/src/declarative/util/qmlfollow.cpp
@@ -239,7 +239,7 @@ void QmlFollowPrivate::stop()
 */
 
 QmlFollow::QmlFollow(QObject *parent)
-: QmlPropertyValueSource(*(new QmlFollowPrivate),parent)
+: QObject(*(new QmlFollowPrivate),parent)
 {
 }
 
diff --git a/src/declarative/util/qmlfollow.h b/src/declarative/util/qmlfollow.h
index 07b2f49..1f6376a 100644
--- a/src/declarative/util/qmlfollow.h
+++ b/src/declarative/util/qmlfollow.h
@@ -52,11 +52,12 @@ QT_BEGIN_NAMESPACE
 QT_MODULE(Declarative)
 
 class QmlFollowPrivate;
-class Q_DECLARATIVE_EXPORT QmlFollow : public QmlPropertyValueSource, 
+class Q_DECLARATIVE_EXPORT QmlFollow : public QObject, public QmlPropertyValueSource,
                                  public QmlParserStatus
 {
     Q_OBJECT
     Q_DECLARE_PRIVATE(QmlFollow)
+    Q_INTERFACES(QmlPropertyValueSource)
     Q_INTERFACES(QmlParserStatus)
 
     Q_PROPERTY(qreal source READ sourceValue WRITE setSourceValue)