Re-add QInternal::EventNotifyCallback

This is needed by QtScript, so we need to keep it for now.

Change-Id: Iee6bd7daf7e86a09242523f5aca72ede413a6981
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

src/corelib/global/qglobal.cpp

@@ -2831,6 +2831,47 @@ int qrand()
     with meaningful parameter names in their signatures.
 */
 
+struct QInternal_CallBackTable {
+    QVector<QList<qInternalCallback> > callbacks;
+};
+
+Q_GLOBAL_STATIC(QInternal_CallBackTable, global_callback_table)
+
+bool QInternal::registerCallback(Callback cb, qInternalCallback callback)
+{
+    if (cb >= 0 && cb < QInternal::LastCallback) {
+        QInternal_CallBackTable *cbt = global_callback_table();
+        cbt->callbacks.resize(cb + 1);
+        cbt->callbacks[cb].append(callback);
+        return true;
+    }
+    return false;
+}
+
+bool QInternal::unregisterCallback(Callback cb, qInternalCallback callback)
+{
+    if (cb >= 0 && cb < QInternal::LastCallback) {
+        QInternal_CallBackTable *cbt = global_callback_table();
+        return (bool) cbt->callbacks[cb].removeAll(callback);
+    }
+    return false;
+}
+
+bool QInternal::activateCallbacks(Callback cb, void **parameters)
+{
+    Q_ASSERT_X(cb >= 0, "QInternal::activateCallback()", "Callback id must be a valid id");
+
+    QInternal_CallBackTable *cbt = global_callback_table();
+    if (cbt && cb < cbt->callbacks.size()) {
+        QList<qInternalCallback> callbacks = cbt->callbacks[cb];
+        bool ret = false;
+        for (int i=0; i<callbacks.size(); ++i)
+            ret |= (callbacks.at(i))(parameters);
+        return ret;
+    }
+    return false;
+}
+
 /*!
     \macro Q_BYTE_ORDER
     \relates <QtGlobal>

src/corelib/global/qnamespace.h

@@ -1599,6 +1599,14 @@ public:
         BottomDock,
         DockCount
     };
+
+    enum Callback {
+        EventNotifyCallback,
+        LastCallback
+    };
+    static bool registerCallback(Callback, qInternalCallback);
+    static bool unregisterCallback(Callback, qInternalCallback);
+    static bool activateCallbacks(Callback, void **);
 };
 
 QT_END_NAMESPACE

src/corelib/kernel/qcoreapplication.cpp

@@ -787,6 +787,14 @@ bool QCoreApplication::testAttribute(Qt::ApplicationAttribute attribute)
 */
 bool QCoreApplication::notifyInternal(QObject *receiver, QEvent *event)
 {
+    // Make it possible for QtScript to hook into events even
+    // though QApplication is subclassed...
+    bool result = false;
+    void *cbdata[] = { receiver, event, &result };
+    if (QInternal::activateCallbacks(QInternal::EventNotifyCallback, cbdata)) {
+        return result;
+    }
+
     // Qt enforces the rule that events can only be sent to objects in
     // the current thread, so receiver->d_func()->threadData is
     // equivalent to QThreadData::current(), just without the function