Allow to filter change events based on a track property

* QNode now has a PropertyTrackMode property
* QScene contains a table of PropertyTrakcMode data
* QPostman checks if a QNode is supposed to receive a change based on the
  information available in the QScene property track mode table
* Unit tests updated and added for QPostman

Change-Id: I3b88037a949020a917c81817f1451ef532065982
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>

15 files changed, 264 insertions, 27 deletions

diff --git a/src/core/changes/qpropertyupdatedchangebase.cpp b/src/core/changes/qpropertyupdatedchangebase.cpp
index 18f2039fc..d33c737e5 100644
--- a/src/core/changes/qpropertyupdatedchangebase.cpp
+++ b/src/core/changes/qpropertyupdatedchangebase.cpp
@@ -46,6 +46,7 @@ namespace Qt3DCore {
 
 QPropertyUpdatedChangeBasePrivate::QPropertyUpdatedChangeBasePrivate()
     : QSceneChangePrivate()
+    , m_isFinal(false)
 {
 }
 
@@ -53,6 +54,11 @@ QPropertyUpdatedChangeBasePrivate::~QPropertyUpdatedChangeBasePrivate()
 {
 }
 
+QPropertyUpdatedChangeBasePrivate *QPropertyUpdatedChangeBasePrivate::get(QPropertyUpdatedChangeBase *q)
+{
+    return q->d_func();
+}
+
 /*!
  * \class Qt3DCore::QPropertyUpdatedChangeBase
  * \inheaderfile Qt3DCore/QPropertyUpdatedChangeBase
diff --git a/src/core/changes/qpropertyupdatedchangebase_p.h b/src/core/changes/qpropertyupdatedchangebase_p.h
index 314b1ea15..3c32b2237 100644
--- a/src/core/changes/qpropertyupdatedchangebase_p.h
+++ b/src/core/changes/qpropertyupdatedchangebase_p.h
@@ -66,7 +66,10 @@ public:
     QPropertyUpdatedChangeBasePrivate();
     virtual ~QPropertyUpdatedChangeBasePrivate();
 
+    static QPropertyUpdatedChangeBasePrivate *get(QPropertyUpdatedChangeBase *q);
+
     Q_DECLARE_PUBLIC(QPropertyUpdatedChangeBase)
+    bool m_isFinal;
 };
 
 } // namespace Qt3DCore
diff --git a/src/core/core.pri b/src/core/core.pri
index becdbb282..458a0328d 100644
--- a/src/core/core.pri
+++ b/src/core/core.pri
@@ -13,7 +13,8 @@ HEADERS += \
     $$PWD/qchangearbiter_p.h \
     $$PWD/qbackendnodefactory_p.h \
     $$PWD/qt3dcore_global_p.h \
-    $$PWD/qscene_p.h
+    $$PWD/qscene_p.h \
+    $$PWD/qpostman_p_p.h
 
 SOURCES += \
     $$PWD/qtickclock.cpp \
diff --git a/src/core/nodes/qnode.cpp b/src/core/nodes/qnode.cpp
index e4bb5d4a3..77d7c0a6b 100644
--- a/src/core/nodes/qnode.cpp
+++ b/src/core/nodes/qnode.cpp
@@ -73,6 +73,7 @@ QNodePrivate::QNodePrivate()
     , m_blockNotifications(false)
     , m_hasBackendNode(false)
     , m_enabled(true)
+    , m_propertyTrackMode(QNode::DefaultTrackMode)
     , m_propertyChangesSetup(false)
     , m_signals(this)
 {
@@ -402,7 +403,6 @@ void QNodePrivate::unsetSceneHelper(QNode *root)
                 m_scene->removeEntityForComponent(c->id(), entity->id());
         }
     }
-
     if (m_scene != nullptr)
         m_scene->removeObservable(root);
     root->d_func()->setScene(nullptr);
@@ -495,8 +495,13 @@ void QNode::sceneChangeEvent(const QSceneChangePtr &change)
  */
 void QNodePrivate::setScene(QScene *scene)
 {
-    if (m_scene != scene)
+    if (m_scene != scene) {
+        if (m_scene != nullptr)
+            m_scene->removePropertyTrackDataForNode(m_id);
         m_scene = scene;
+        // set PropertyTrackData in the scene
+        updatePropertyTrackMode();
+    }
 }
 
 /*!
@@ -580,6 +585,16 @@ void QNodePrivate::insertTree(QNode *treeRoot, int depth)
         treeRoot->setParent(q_func());
 }
 
+void QNodePrivate::updatePropertyTrackMode()
+{
+    if (m_scene != nullptr) {
+        QScene::NodePropertyTrackData trackData;
+        trackData.updateMode = m_propertyTrackMode;
+        trackData.namedProperties = m_trackedProperties;
+        m_scene->setPropertyTrackDataForNode(m_id,trackData);
+    }
+}
+
 /*!
     \internal
  */
@@ -769,6 +784,34 @@ void QNode::setEnabled(bool isEnabled)
     emit enabledChanged(isEnabled);
 }
 
+void QNode::setPropertyTrackMode(QNode::PropertyTrackMode mode)
+{
+    Q_D(QNode);
+    if (d->m_propertyTrackMode == mode)
+        return;
+
+    d->m_propertyTrackMode = mode;
+    // The backend doesn't care about such notification
+    const bool blocked = blockNotifications(true);
+    emit propertyUpdateModeChanged(mode);
+    blockNotifications(blocked);
+    d->updatePropertyTrackMode();
+}
+
+void QNode::setTrackedProperties(const QStringList &trackedProperties)
+{
+    Q_D(QNode);
+    if (d->m_trackedProperties == trackedProperties)
+        return;
+
+    d->m_trackedProperties = trackedProperties;
+    // The backend doesn't care about such notification
+    const bool blocked = blockNotifications(true);
+    emit trackedPropertiesChanged(trackedProperties);
+    blockNotifications(blocked);
+    d->updatePropertyTrackMode();
+}
+
 /*!
     \property Qt3DCore::QNode::enabled
 
@@ -785,6 +828,32 @@ bool QNode::isEnabled() const
     return d->m_enabled;
 }
 
+/*!
+    \property Qt3DCore::QNode::propertyTrackMode
+
+    Holds the property track mode which determines whether a QNode should
+    be listening for property updates
+
+    By default it is set to QNode::DontTrackProperties
+*/
+QNode::PropertyTrackMode QNode::propertyTrackMode() const
+{
+    Q_D(const QNode);
+    return d->m_propertyTrackMode;
+}
+
+/*!
+    \property Qt3DCore::QNode::trackedProperties
+
+    Holds the names of the properties to be tracked when propertyTrackMode is
+    set to TrackNamedProperties.
+*/
+QStringList QNode::trackedProperties() const
+{
+    Q_D(const QNode);
+    return d->m_trackedProperties;
+}
+
 QNodeCreatedChangeBasePtr QNode::createNodeCreationChange() const
 {
     // Uncomment this when implementing new frontend and backend types.
diff --git a/src/core/nodes/qnode.h b/src/core/nodes/qnode.h
index cadcc7d5c..75ea61cc7 100644
--- a/src/core/nodes/qnode.h
+++ b/src/core/nodes/qnode.h
@@ -69,7 +69,17 @@ class QT3DCORESHARED_EXPORT QNode : public QObject
     Q_OBJECT
     Q_PROPERTY(Qt3DCore::QNode *parent READ parentNode WRITE setParent NOTIFY parentChanged)
     Q_PROPERTY(bool enabled READ isEnabled WRITE setEnabled NOTIFY enabledChanged)
+    Q_PROPERTY(PropertyTrackMode propertyTrackMode READ propertyTrackMode WRITE setPropertyTrackMode NOTIFY propertyUpdateModeChanged)
+    Q_PROPERTY(QStringList trackedProperties READ trackedProperties WRITE setTrackedProperties NOTIFY trackedPropertiesChanged)
 public:
+
+    enum PropertyTrackMode {
+        DefaultTrackMode,
+        TrackNamedPropertiesMode,
+        TrackAllPropertiesMode
+    };
+    Q_ENUM(PropertyTrackMode)
+
     explicit QNode(QNode *parent = nullptr);
     virtual ~QNode();
 
@@ -82,14 +92,20 @@ public:
     QNodeVector childNodes() const;
 
     bool isEnabled() const;
+    PropertyTrackMode propertyTrackMode() const;
+    QStringList trackedProperties() const;
 
 public Q_SLOTS:
     void setParent(QNode *parent);
     void setEnabled(bool isEnabled);
+    void setPropertyTrackMode(PropertyTrackMode mode);
+    void setTrackedProperties(const QStringList &trackedProperties);
 
 Q_SIGNALS:
     void parentChanged(QObject *parent);
     void enabledChanged(bool enabled);
+    void propertyUpdateModeChanged(PropertyTrackMode mode);
+    void trackedPropertiesChanged(const QStringList &trackedProperties);
     void nodeDestroyed();
 
 protected:
diff --git a/src/core/nodes/qnode_p.h b/src/core/nodes/qnode_p.h
index a90011128..5d6329e62 100644
--- a/src/core/nodes/qnode_p.h
+++ b/src/core/nodes/qnode_p.h
@@ -84,6 +84,7 @@ public:
     void notifyObservers(const QSceneChangePtr &change) Q_DECL_OVERRIDE;
 
     void insertTree(QNode *treeRoot, int depth = 0);
+    void updatePropertyTrackMode();
 
     Q_DECLARE_PUBLIC(QNode)
 
@@ -97,6 +98,8 @@ public:
     bool m_blockNotifications;
     bool m_hasBackendNode;
     bool m_enabled;
+    QNode::PropertyTrackMode m_propertyTrackMode;
+    QStringList m_trackedProperties;
 
     static QNodePrivate *get(QNode *q);
     static void nodePtrDeleter(QNode *q);
diff --git a/src/core/qchangearbiter.cpp b/src/core/qchangearbiter.cpp
index 3bd3f69e8..a7ca3ed40 100644
--- a/src/core/qchangearbiter.cpp
+++ b/src/core/qchangearbiter.cpp
@@ -132,9 +132,11 @@ void QChangeArbiter::distributeQueueChanges(QChangeQueue *changeQueue)
                         (change->deliveryFlags() & QSceneChange::BackendNodes))
                     observer.second->sceneChangeEvent(change);
             }
+            // Also send change to the postman
             if (change->deliveryFlags() & QSceneChange::Nodes) {
-                // Also send change to the postman
-                m_postman->sceneChangeEvent(change);
+                // Check if QNode actually cares about the change
+                if (m_postman->shouldNotifyFrontend(change))
+                    m_postman->sceneChangeEvent(change);
             }
         }
     }
diff --git a/src/core/qchangearbiter_p.h b/src/core/qchangearbiter_p.h
index e3fdcad9b..e381abc65 100644
--- a/src/core/qchangearbiter_p.h
+++ b/src/core/qchangearbiter_p.h
@@ -136,14 +136,8 @@ private:
     QMutex m_mutex;
     QAbstractAspectJobManager *m_jobManager;
 
-    // The lists of observers indexed by observable. We maintain two
-    // distinct hashes:
-    //
-    // m_aspectObservations is for observables owned by aspects
+    // The lists of observers indexed by observable (QNodeId).
     // m_nodeObservations is for observables in the main thread's object tree
-    //
-    // We keep these distinct because we do not manage the main thread which means
-    // the mechanisms for working with objects there is different.
     QHash<QNodeId, QObserverList> m_nodeObservations;
     QList<QSceneObserverInterface *> m_sceneObservers;
 
diff --git a/src/core/qpostman.cpp b/src/core/qpostman.cpp
index ac78450c6..2b8e6c3a8 100644
--- a/src/core/qpostman.cpp
+++ b/src/core/qpostman.cpp
@@ -38,30 +38,22 @@
 ****************************************************************************/
 
 #include "qpostman_p.h"
-#include <private/qobject_p.h>
+#include "qpostman_p_p.h"
 #include <Qt3DCore/qpropertyupdatedchange.h>
 #include <Qt3DCore/private/qscene_p.h>
 #include <Qt3DCore/private/qlockableobserverinterface_p.h>
 #include <Qt3DCore/qnode.h>
 #include <Qt3DCore/private/qnode_p.h>
+#include <Qt3DCore/private/qpropertyupdatedchangebase_p.h>
 
 QT_BEGIN_NAMESPACE
 
 namespace Qt3DCore {
 
-class QPostmanPrivate : public QObjectPrivate
+QPostmanPrivate *QPostmanPrivate::get(QPostman *q)
 {
-public:
-    QPostmanPrivate()
-        : QObjectPrivate()
-        , m_scene(nullptr)
-    {
-    }
-
-    Q_DECLARE_PUBLIC(QPostman)
-    QScene *m_scene;
-    std::vector<QSceneChangePtr> m_batch;
-};
+    return q->d_func();
+}
 
 QPostman::QPostman(QObject *parent)
     : QObject(*new QPostmanPrivate, parent)
@@ -118,6 +110,32 @@ void QPostman::notifyBackend(const QSceneChangePtr &change)
     d->m_batch.push_back(change);
 }
 
+// AspectThread
+bool QPostman::shouldNotifyFrontend(const QSceneChangePtr &e)
+{
+    Q_D(QPostman);
+    const QPropertyUpdatedChangePtr propertyChange = qSharedPointerDynamicCast<QPropertyUpdatedChange>(e);
+    if (Q_LIKELY(d->m_scene != nullptr) && !propertyChange.isNull()) {
+        const bool isFinal = QPropertyUpdatedChangeBasePrivate::get(propertyChange.data())->m_isFinal;
+        if (isFinal)
+            return true;
+        const QScene::NodePropertyTrackData propertyTrackData = d->m_scene->lookupNodePropertyTrackData(e->subjectId());
+        switch (propertyTrackData.updateMode) {
+        case QNode::TrackAllPropertiesMode:
+            return true;
+        case QNode::TrackNamedPropertiesMode:
+            return propertyTrackData.namedProperties.contains(QLatin1String(propertyChange->propertyName()));
+        case QNode::DefaultTrackMode:
+            return false;
+        default:
+            Q_UNREACHABLE();
+            return false;
+        }
+    }
+    return true;
+}
+
+// Main Thread
 void QPostman::notifyFrontendNode(const QSceneChangePtr &e)
 {
     Q_D(QPostman);
diff --git a/src/core/qpostman_p.h b/src/core/qpostman_p.h
index 4fe788960..cbc4048ce 100644
--- a/src/core/qpostman_p.h
+++ b/src/core/qpostman_p.h
@@ -66,9 +66,10 @@ class QT3DCORE_PRIVATE_EXPORT QAbstractPostman : public QObserverInterface
 public:
     virtual void setScene(QScene *sceneLookup) = 0;
     virtual void notifyBackend(const QSceneChangePtr &change) = 0;
+    virtual bool shouldNotifyFrontend(const QSceneChangePtr &change) = 0;
 };
 
-class QPostman Q_DECL_FINAL
+class Q_AUTOTEST_EXPORT QPostman Q_DECL_FINAL
         : public QObject
         , public QAbstractPostman
 {
@@ -80,6 +81,7 @@ public:
     void setScene(QScene *sceneLookup) Q_DECL_FINAL;
     void sceneChangeEvent(const QSceneChangePtr &e) Q_DECL_FINAL;
     void notifyBackend(const QSceneChangePtr &change) Q_DECL_FINAL;
+    bool shouldNotifyFrontend(const QSceneChangePtr &e) Q_DECL_FINAL;
 
 public Q_SLOTS:
     void submitChangeBatch();
diff --git a/src/core/qpostman_p_p.h b/src/core/qpostman_p_p.h
new file mode 100644
index 000000000..1b5cca3c9
--- /dev/null
+++ b/src/core/qpostman_p_p.h
@@ -0,0 +1,85 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Klaralvdalens Datakonsult AB (KDAB).
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt3D module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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.LGPL3 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-3.0.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 (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QT3DCORE_QPOSTMAN_P_P_H
+#define QT3DCORE_QPOSTMAN_P_P_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 <private/qobject_p.h>
+#include <Qt3DCore/private/qt3dcore_global_p.h>
+
+QT_BEGIN_NAMESPACE
+
+namespace Qt3DCore {
+
+class QScene;
+class QPostman;
+
+class QT3DCORE_PRIVATE_EXPORT QPostmanPrivate : public QObjectPrivate
+{
+public:
+    QPostmanPrivate()
+        : QObjectPrivate()
+        , m_scene(nullptr)
+    {
+    }
+
+    static QPostmanPrivate *get(QPostman *q);
+
+    Q_DECLARE_PUBLIC(QPostman)
+    QScene *m_scene;
+    std::vector<QSceneChangePtr> m_batch;
+};
+
+} // Qt3DCore
+
+QT_END_NAMESPACE
+
+#endif // QT3DCORE_QPOSTMAN_P_P_H
diff --git a/src/core/qscene.cpp b/src/core/qscene.cpp
index 42c3a2bc8..972659131 100644
--- a/src/core/qscene.cpp
+++ b/src/core/qscene.cpp
@@ -63,8 +63,10 @@ public:
     QMultiHash<QNodeId, QNodeId> m_componentToEntities;
     QMultiHash<QNodeId, QObservableInterface *> m_observablesLookupTable;
     QHash<QObservableInterface *, QNodeId> m_observableToUuid;
+    QHash<QNodeId, QScene::NodePropertyTrackData> m_nodePropertyTrackModeLookupTable;
     QLockableObserverInterface *m_arbiter;
     mutable QReadWriteLock m_lock;
+    mutable QReadWriteLock m_nodePropertyTrackModeLock;
 };
 
 
@@ -213,6 +215,27 @@ bool QScene::hasEntityForComponent(QNodeId componentUuid, QNodeId entityUuid)
     return d->m_componentToEntities.values(componentUuid).contains(entityUuid);
 }
 
+QScene::NodePropertyTrackData QScene::lookupNodePropertyTrackData(QNodeId id) const
+{
+    Q_D(const QScene);
+    QReadLocker lock(&d->m_nodePropertyTrackModeLock);
+    return d->m_nodePropertyTrackModeLookupTable.value(id);
+}
+
+void QScene::setPropertyTrackDataForNode(QNodeId nodeId, const QScene::NodePropertyTrackData &data)
+{
+    Q_D(QScene);
+    QWriteLocker lock(&d->m_nodePropertyTrackModeLock);
+    d->m_nodePropertyTrackModeLookupTable.insert(nodeId, data);
+}
+
+void QScene::removePropertyTrackDataForNode(QNodeId nodeId)
+{
+    Q_D(QScene);
+    QWriteLocker lock(&d->m_nodePropertyTrackModeLock);
+    d->m_nodePropertyTrackModeLookupTable.remove(nodeId);
+}
+
 } // Qt3D
 
 QT_END_NAMESPACE
diff --git a/src/core/qscene_p.h b/src/core/qscene_p.h
index 6b4009538..1a313c249 100644
--- a/src/core/qscene_p.h
+++ b/src/core/qscene_p.h
@@ -53,13 +53,13 @@
 
 #include <Qt3DCore/private/qt3dcore_global_p.h>
 #include <Qt3DCore/private/qobservableinterface_p.h>
+#include <Qt3DCore/qnode.h>
 #include <QScopedPointer>
 
 QT_BEGIN_NAMESPACE
 
 namespace Qt3DCore {
 
-class QNode;
 class QScenePrivate;
 class QAspectEngine;
 
@@ -92,6 +92,16 @@ public:
     void removeEntityForComponent(QNodeId componentUuid, QNodeId entityUuid);
     bool hasEntityForComponent(QNodeId componentUuid, QNodeId entityUuid);
 
+    // Node -> Property Update Data
+    struct NodePropertyTrackData
+    {
+        QNode::PropertyTrackMode updateMode = QNode::DefaultTrackMode;
+        QStringList namedProperties;
+    };
+    NodePropertyTrackData lookupNodePropertyTrackData(QNodeId id) const;
+    void setPropertyTrackDataForNode(QNodeId id, const NodePropertyTrackData &data);
+    void removePropertyTrackDataForNode(QNodeId id);
+
 private:
     Q_DECLARE_PRIVATE(QScene)
     QScopedPointer<QScenePrivate> d_ptr;
diff --git a/src/render/geometry/buffer.cpp b/src/render/geometry/buffer.cpp
index aaae9825f..df0bc3c92 100644
--- a/src/render/geometry/buffer.cpp
+++ b/src/render/geometry/buffer.cpp
@@ -41,6 +41,7 @@
 #include <Qt3DCore/qpropertyupdatedchange.h>
 #include <Qt3DRender/private/buffermanager_p.h>
 #include <Qt3DRender/private/qbuffer_p.h>
+#include <Qt3DCore/private/qpropertyupdatedchangebase_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -92,6 +93,7 @@ void Buffer::executeFunctor()
         e->setDeliveryFlags(Qt3DCore::QSceneChange::DeliverToAll);
         e->setPropertyName("data");
         e->setValue(QVariant::fromValue(m_data));
+        Qt3DCore::QPropertyUpdatedChangeBasePrivate::get(e.data())->m_isFinal = true;
         notifyObservers(e);
     }
 }
diff --git a/src/render/io/scene.cpp b/src/render/io/scene.cpp
index cf1ca4736..2057ffd3d 100644
--- a/src/render/io/scene.cpp
+++ b/src/render/io/scene.cpp
@@ -46,6 +46,7 @@
 #include <Qt3DRender/private/qsceneloader_p.h>
 #include <Qt3DRender/private/scenemanager_p.h>
 #include <QtCore/qcoreapplication.h>
+#include <Qt3DCore/private/qpropertyupdatedchangebase_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -72,6 +73,7 @@ void Scene::setStatus(QSceneLoader::Status status)
     e->setDeliveryFlags(Qt3DCore::QSceneChange::DeliverToAll);
     e->setPropertyName("status");
     e->setValue(QVariant::fromValue(status));
+    Qt3DCore::QPropertyUpdatedChangeBasePrivate::get(e.data())->m_isFinal = true;
     notifyObservers(e);
 }
 
@@ -114,6 +116,7 @@ void Scene::setSceneSubtree(Qt3DCore::QEntity *subTree)
     e->setDeliveryFlags(Qt3DCore::QSceneChange::DeliverToAll);
     e->setPropertyName("scene");
     e->setValue(QVariant::fromValue(subTree));
+    Qt3DCore::QPropertyUpdatedChangeBasePrivate::get(e.data())->m_isFinal = true;
     notifyObservers(e);
 }