Add QNodeDestroyedChange and send from QNode dtor

Taking care not to do this recursively. One event can take care of
notifying the backend of an entire sub-tree being destroyed.

Change-Id: Iabf849317943b982eebac72e201e117c2f174026
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

9 files changed, 290 insertions, 4 deletions

diff --git a/src/core/aspects/qaspectengine.cpp b/src/core/aspects/qaspectengine.cpp
index b76aae603..6a33c4536 100644
--- a/src/core/aspects/qaspectengine.cpp
+++ b/src/core/aspects/qaspectengine.cpp
@@ -109,6 +109,13 @@ 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());
 }
 
 QAspectEngine::QAspectEngine(QObject *parent)
diff --git a/src/core/core.pri b/src/core/core.pri
index 606a72174..36c134ee9 100644
--- a/src/core/core.pri
+++ b/src/core/core.pri
@@ -34,7 +34,8 @@ HEADERS += \
     $$PWD/qt3dcore_global_p.h \
     $$PWD/qscene_p.h \
     $$PWD/qnodecreatedchange_p.h \
-    $$PWD/qnodecreatedchange.h
+    $$PWD/qnodecreatedchange.h \
+    $$PWD/qnodedestroyedchange_p.h
 
 SOURCES += \
     $$PWD/qtickclock.cpp \
@@ -51,4 +52,5 @@ SOURCES += \
     $$PWD/qscene.cpp \
     $$PWD/qbackendscenepropertychange.cpp \
     $$PWD/qbackendnodefactory.cpp \
-    $$PWD/qnodecreatedchange.cpp
+    $$PWD/qnodecreatedchange.cpp \
+    $$PWD/qnodedestroyedchange.cpp
diff --git a/src/core/nodes/nodes.pri b/src/core/nodes/nodes.pri
index 5ecf2f36a..56e90b2fd 100644
--- a/src/core/nodes/nodes.pri
+++ b/src/core/nodes/nodes.pri
@@ -12,7 +12,8 @@ HEADERS += \
     $$PWD/qnodeid.h \
     $$PWD/qnodevisitor_p.h \
     $$PWD/qabstractnodefactory.h \
-    $$PWD/propertychangehandler_p.h
+    $$PWD/propertychangehandler_p.h \
+    $$PWD/qdestructionidandtypecollector_p.h
 
 SOURCES += \
     $$PWD/qnode.cpp \
@@ -22,4 +23,5 @@ SOURCES += \
     $$PWD/qnodeid.cpp \
     $$PWD/qnodevisitor.cpp \
     $$PWD/qabstractnodefactory.cpp \
-    $$PWD/propertychangehandler.cpp
+    $$PWD/propertychangehandler.cpp \
+    $$PWD/qdestructionidandtypecollector.cpp
diff --git a/src/core/nodes/qdestructionidandtypecollector.cpp b/src/core/nodes/qdestructionidandtypecollector.cpp
new file mode 100644
index 000000000..2c611a490
--- /dev/null
+++ b/src/core/nodes/qdestructionidandtypecollector.cpp
@@ -0,0 +1,51 @@
+/****************************************************************************
+**
+** 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 "qdestructionidandtypecollector_p.h"
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+QDestructionIdAndTypeCollector::QDestructionIdAndTypeCollector(QNode *rootNode)
+{
+    QNodeVisitor visitor;
+    visitor.traverse(rootNode, this, &QDestructionIdAndTypeCollector::collectIdAndType);
+}
+
+QT_END_NAMESPACE
+
+} // namespace Qt3DCore
diff --git a/src/core/nodes/qdestructionidandtypecollector_p.h b/src/core/nodes/qdestructionidandtypecollector_p.h
new file mode 100644
index 000000000..3f64a409e
--- /dev/null
+++ b/src/core/nodes/qdestructionidandtypecollector_p.h
@@ -0,0 +1,83 @@
+/****************************************************************************
+**
+** 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_QIDTYPEVISITOR_H
+#define QT3DCORE_QIDTYPEVISITOR_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/private/qnodevisitor_p.h>
+#include <Qt3DCore/private/qentity_p.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+class QDestructionIdAndTypeCollector
+{
+public:
+    QDestructionIdAndTypeCollector(QNode *rootNode);
+
+    QVector<QNodeIdTypePair> subtreeIdsAndTypes() const { return m_subtreeIdsAndTypes; }
+
+private:
+    void collectIdAndType(QNode *node)
+    {
+        QNodeIdTypePair idAndType(node->id(), QNodePrivate::get(node)->m_typeInfo);
+        m_subtreeIdsAndTypes.push_back(idAndType);
+
+        // Mark this node as having been handled for destruction so we don't
+        // repeat it unnecessarily in an O(n^2) manner
+        QNodePrivate::get(node)->m_destroyedChangeCreated = true;
+    }
+
+    QVector<QNodeIdTypePair> m_subtreeIdsAndTypes;
+};
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
+
+#endif // QT3DCORE_QIDTYPEVISITOR_H
diff --git a/src/core/nodes/qnode.cpp b/src/core/nodes/qnode.cpp
index 7d872de5f..f6b43a925 100644
--- a/src/core/nodes/qnode.cpp
+++ b/src/core/nodes/qnode.cpp
@@ -43,6 +43,8 @@
 #include <Qt3DCore/qentity.h>
 #include <Qt3DCore/qscenepropertychange.h>
 #include <Qt3DCore/qaspectengine.h>
+#include <Qt3DCore/private/qdestructionidandtypecollector_p.h>
+#include <Qt3DCore/private/qnodedestroyedchange_p.h>
 #include <Qt3DCore/private/qscene_p.h>
 #include <Qt3DCore/private/qpostman_p.h>
 #include <QEvent>
@@ -66,6 +68,7 @@ QNodePrivate::QNodePrivate()
     , m_id(QNodeId::createId())
     , m_blockNotifications(false)
     , m_wasCleanedUp(false)
+    , m_destroyedChangeCreated(false)
     , m_enabled(true)
     , m_propertyChangesSetup(false)
     , m_signals(this)
@@ -467,6 +470,15 @@ void QNode::copy(const QNode *ref)
 QNode::~QNode()
 {
     Q_ASSERT_X(QNodePrivate::get(this)->m_wasCleanedUp, Q_FUNC_INFO, "QNode::cleanup should have been called by now. A Qt3DCore::QNode subclass didn't call QNode::cleanup in its destructor");
+
+    // Create a QNodeDestroyedChange for this node that informs the backend that
+    // this node and all of its children are going away
+    Q_D(QNode);
+    if (!d->m_destroyedChangeCreated) {
+        const QDestructionIdAndTypeCollector collector(this);
+        const auto destroyedChange = QNodeDestroyedChangePtr::create(this, collector.subtreeIdsAndTypes());
+        d->notifyObservers(destroyedChange);
+    }
 }
 
 /*!
diff --git a/src/core/nodes/qnode_p.h b/src/core/nodes/qnode_p.h
index c01da7adc..d8aa7e98f 100644
--- a/src/core/nodes/qnode_p.h
+++ b/src/core/nodes/qnode_p.h
@@ -85,10 +85,12 @@ public:
     // For now this just protects access to the m_changeArbiter.
     // Later on we may decide to extend support for multiple observers.
     QAbstractArbiter *m_changeArbiter;
+    QMetaObject *m_typeInfo;
     QScene *m_scene;
     mutable QNodeId m_id;
     bool m_blockNotifications;
     bool m_wasCleanedUp;
+    bool m_destroyedChangeCreated;
     bool m_enabled;
 
     static QNodePrivate *get(QNode *q);
diff --git a/src/core/qnodedestroyedchange.cpp b/src/core/qnodedestroyedchange.cpp
new file mode 100644
index 000000000..08c7e83ae
--- /dev/null
+++ b/src/core/qnodedestroyedchange.cpp
@@ -0,0 +1,51 @@
+/****************************************************************************
+**
+** 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 "qnodedestroyedchange_p.h"
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+QNodeDestroyedChange::QNodeDestroyedChange(const QNode *node, const QVector<QNodeIdTypePair> &subtreeIdsAndTypes)
+    : QSceneChange(NodeDeleted, QSceneChange::Node, node->id(), QSceneChange::Standard)
+    , m_subtreeIdsAndTypes(subtreeIdsAndTypes)
+{
+}
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
diff --git a/src/core/qnodedestroyedchange_p.h b/src/core/qnodedestroyedchange_p.h
new file mode 100644
index 000000000..bef65cbb5
--- /dev/null
+++ b/src/core/qnodedestroyedchange_p.h
@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** 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_QNODEDESTROYEDCHANGE_H
+#define QT3DCORE_QNODEDESTROYEDCHANGE_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/qscenechange.h>
+#include <Qt3DCore/private/qentity_p.h>
+#include <QtCore/qsharedpointer.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+class QNodeDestroyedChange : public QSceneChange
+{
+public:
+    explicit QNodeDestroyedChange(const QNode *node, const QVector<QNodeIdTypePair> &subtreeIdsAndTypes);
+
+    QVector<QNodeIdTypePair> subtreeIdsAndTypes() const { return m_subtreeIdsAndTypes; }
+
+private:
+    QVector<QNodeIdTypePair> m_subtreeIdsAndTypes;
+};
+
+typedef QSharedPointer<QNodeDestroyedChange> QNodeDestroyedChangePtr;
+
+} // namespace Qt3DCore
+
+QT_END_NAMESPACE
+
+#endif // QT3DCORE_QNODEDESTROYEDCHANGE_H