Add a signal emitted callback to QAbstractDeclarativeData

For property notify signals, QtDeclarative can manage connections
in a more special case - and more performant - way.  This patch
adds a callback hook so that QtDeclarative can intercept signals
being emitted by declarative objects.

Change-Id: I72554e80df0a4257da65d81cc1c5db88a11446a4
Reviewed-on: http://codereview.qt.nokia.com/3363
Reviewed-by: Martin Jones <martin.jones@nokia.com>

src/corelib/kernel/qobject.cpp

@@ -147,6 +147,7 @@ private:
 void (*QAbstractDeclarativeData::destroyed)(QAbstractDeclarativeData *, QObject *) = 0;
 void (*QAbstractDeclarativeData::parentChanged)(QAbstractDeclarativeData *, QObject *, QObject *) = 0;
 void (*QAbstractDeclarativeData::objectNameChanged)(QAbstractDeclarativeData *, QObject *) = 0;
+void (*QAbstractDeclarativeData::signalEmitted)(QAbstractDeclarativeData *, QObject *, int, void **) = 0;
 
 QObjectData::~QObjectData() {}
 
@@ -3270,6 +3271,10 @@ void QMetaObject::activate(QObject *sender, const QMetaObject *m, int local_sign
 
     int signal_index = signalOffset + local_signal_index;
 
+    if (sender->d_func()->declarativeData && QAbstractDeclarativeData::signalEmitted)
+        QAbstractDeclarativeData::signalEmitted(sender->d_func()->declarativeData, sender, 
+                                                methodOffset + local_signal_index, argv);
+
     if (!sender->d_func()->isSignalConnected(signal_index))
         return; // nothing connected to these signals, and no spy
 

src/corelib/kernel/qobject_p.h

@@ -91,6 +91,7 @@ public:
     static void (*destroyed)(QAbstractDeclarativeData *, QObject *);
     static void (*parentChanged)(QAbstractDeclarativeData *, QObject *, QObject *);
     static void (*objectNameChanged)(QAbstractDeclarativeData *, QObject *);
+    static void (*signalEmitted)(QAbstractDeclarativeData *, QObject *, int, void **);
 };
 
 class Q_CORE_EXPORT QObjectPrivate : public QObjectData