Add QNodeCreatedChangeGenerator helper

This can then be used by the QAspectEngine to create creation changes
at startup and by QNodePrivate to generate creation changes for dynamic
objects at runtime.

Change-Id: Idf13fc249de7238a8c5803634a825bd86bc3c52a
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

6 files changed, 149 insertions, 19 deletions

diff --git a/src/core/aspects/qaspectengine.cpp b/src/core/aspects/qaspectengine.cpp
index 6a33c4536..769973632 100644
--- a/src/core/aspects/qaspectengine.cpp
+++ b/src/core/aspects/qaspectengine.cpp
@@ -56,6 +56,7 @@
 #include "qentity.h"
 #include "qcomponent.h"
 #include <Qt3DCore/private/qeventfilterservice_p.h>
+#include <Qt3DCore/private/qnodecreatedchangegenerator_p.h>
 #include <Qt3DCore/private/qservicelocator_p.h>
 
 QT_BEGIN_NAMESPACE
@@ -100,22 +101,8 @@ void QAspectEnginePrivate::initEntity(QEntity *entity)
 
 void QAspectEnginePrivate::generateCreationChanges(QNode *root)
 {
-    m_creationChanges.clear();
-    QNodeVisitor creationVisitor;
-    creationVisitor.traverse(root, this, &QAspectEnginePrivate::createCreationChange);
-}
-
-void QAspectEnginePrivate::createCreationChange(QNode *node)
-{
-    const auto creationChange = node->createNodeCreationChange();
-    m_creationChanges.push_back(creationChange);
-
-    // Store the metaobject of the node in the QNode so that we have it available
-    // to us during destruction in the QNode destructor. This allows us to send
-    // the QNodeId and the metaobject as typeinfo to the backend aspects so they
-    // in turn can find the correct QBackendNodeMapper object to handle the destruction
-    // of the corresponding backend nodes.
-    QNodePrivate::get(node)->m_typeInfo = const_cast<QMetaObject*>(creationChange->metaObject());
+    const QNodeCreatedChangeGenerator generator(root);
+    m_creationChanges = generator.creationChanges();
 }
 
 QAspectEngine::QAspectEngine(QObject *parent)
diff --git a/src/core/aspects/qaspectengine_p.h b/src/core/aspects/qaspectengine_p.h
index 7a46d5cc2..b2b88d266 100644
--- a/src/core/aspects/qaspectengine_p.h
+++ b/src/core/aspects/qaspectengine_p.h
@@ -90,7 +90,6 @@ public:
     void initEntity(QEntity *entity);
 
     void generateCreationChanges(QNode *rootNode);
-    void createCreationChange(QNode *node); // visitor function
     QVector<QNodeCreatedChangeBasePtr> m_creationChanges;
 };
 
diff --git a/src/core/nodes/nodes.pri b/src/core/nodes/nodes.pri
index 56e90b2fd..872352bf1 100644
--- a/src/core/nodes/nodes.pri
+++ b/src/core/nodes/nodes.pri
@@ -13,7 +13,8 @@ HEADERS += \
     $$PWD/qnodevisitor_p.h \
     $$PWD/qabstractnodefactory.h \
     $$PWD/propertychangehandler_p.h \
-    $$PWD/qdestructionidandtypecollector_p.h
+    $$PWD/qdestructionidandtypecollector_p.h \
+    $$PWD/qnodecreatedchangegenerator_p.h
 
 SOURCES += \
     $$PWD/qnode.cpp \
@@ -24,4 +25,5 @@ SOURCES += \
     $$PWD/qnodevisitor.cpp \
     $$PWD/qabstractnodefactory.cpp \
     $$PWD/propertychangehandler.cpp \
-    $$PWD/qdestructionidandtypecollector.cpp
+    $$PWD/qdestructionidandtypecollector.cpp \
+    $$PWD/qnodecreatedchangegenerator.cpp
diff --git a/src/core/nodes/qnode.h b/src/core/nodes/qnode.h
index 86ddeb39c..595992604 100644
--- a/src/core/nodes/qnode.h
+++ b/src/core/nodes/qnode.h
@@ -126,6 +126,7 @@ private:
 
     friend class QAspectEngine;
     friend class QAspectEnginePrivate;
+    friend class QNodeCreatedChangeGenerator;
     friend class QPostman;
     friend class QScene;
 };
diff --git a/src/core/nodes/qnodecreatedchangegenerator.cpp b/src/core/nodes/qnodecreatedchangegenerator.cpp
new file mode 100644
index 000000000..c350c866a
--- /dev/null
+++ b/src/core/nodes/qnodecreatedchangegenerator.cpp
@@ -0,0 +1,52 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qnodecreatedchangegenerator_p.h"
+#include <Qt3DCore/private/qnodevisitor_p.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+QNodeCreatedChangeGenerator::QNodeCreatedChangeGenerator(QNode *rootNode)
+{
+    QNodeVisitor visitor;
+    visitor.traverse(rootNode, this, &QNodeCreatedChangeGenerator::createCreationChange);
+}
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
diff --git a/src/core/nodes/qnodecreatedchangegenerator_p.h b/src/core/nodes/qnodecreatedchangegenerator_p.h
new file mode 100644
index 000000000..9e4dedafe
--- /dev/null
+++ b/src/core/nodes/qnodecreatedchangegenerator_p.h
@@ -0,0 +1,89 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL3$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPLv3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or later as published by the Free
+** Software Foundation and appearing in the file LICENSE.GPL included in
+** the packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 2.0 requirements will be
+** met: http://www.gnu.org/licenses/gpl-2.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT3DCORE_QNODECREATEDCHANGEGENERATOR_H
+#define QT3DCORE_QNODECREATEDCHANGEGENERATOR_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of other Qt classes.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <Qt3DCore/qt3dcore_global.h>
+#include <Qt3DCore/qnode.h>
+#include <Qt3DCore/qnodecreatedchange.h>
+#include <Qt3DCore/private/qnode_p.h>
+#include <QtCore/qvector.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+class QNodeCreatedChangeGenerator
+{
+public:
+    QNodeCreatedChangeGenerator(QNode *rootNode);
+
+    QVector<QNodeCreatedChangeBasePtr> creationChanges() const { return m_creationChanges; }
+
+private:
+    void createCreationChange(QNode *node)
+    {
+        const auto creationChange = node->createNodeCreationChange();
+        m_creationChanges.push_back(creationChange);
+
+        // Store the metaobject of the node in the QNode so that we have it available
+        // to us during destruction in the QNode destructor. This allows us to send
+        // the QNodeId and the metaobject as typeinfo to the backend aspects so they
+        // in turn can find the correct QBackendNodeMapper object to handle the destruction
+        // of the corresponding backend nodes.
+        QNodePrivate::get(node)->m_typeInfo = const_cast<QMetaObject*>(creationChange->metaObject());
+    }
+
+    QVector<QNodeCreatedChangeBasePtr> m_creationChanges;
+};
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
+
+#endif // QT3DCORE_QNODECREATEDCHANGEGENERATOR_H