Fix for loading using a Mesh

Added code path avoiding cloning for setting the geometry on the QMesh
which is a QGeopmetryRenderer. This is actually much easier without
cloning. We simply create the QGeometry on the backend, move it to the
main thread, then send it over in a change. In the frontend
QGeometryRenderer, we just extract the pointer to the QGeometry and set
it on the geometry property.

Change-Id: I06db5cba52d783323141a7b1d72b326e319b4960
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

3 files changed, 27 insertions, 18 deletions

diff --git a/src/render/geometry/geometryrenderer.cpp b/src/render/geometry/geometryrenderer.cpp
index 6ff57ee43..bc89a968c 100644
--- a/src/render/geometry/geometryrenderer.cpp
+++ b/src/render/geometry/geometryrenderer.cpp
@@ -46,6 +46,9 @@
 #include <Qt3DCore/qnodeaddedpropertychange.h>
 #include <Qt3DCore/qnoderemovedpropertychange.h>
 #include <Qt3DCore/private/qnode_p.h>
+#include <QtCore/qcoreapplication.h>
+
+#include <memory>
 
 QT_BEGIN_NAMESPACE
 
@@ -191,15 +194,21 @@ void GeometryRenderer::sceneChangeEvent(const Qt3DCore::QSceneChangePtr &e)
 void GeometryRenderer::executeFunctor()
 {
     Q_ASSERT(m_geometryFactory);
-    QGeometry *geometry = (*m_geometryFactory)();
+    std::unique_ptr<QGeometry> geometry((*m_geometryFactory)());
+    if (!geometry)
+        return;
+
+    // Move the QGeometry object to the main thread and notify the
+    // corresponding QGeometryRenderer
+    const auto appThread = QCoreApplication::instance()->thread();
+    geometry->moveToThread(appThread);
 
-    QBackendNodePropertyChangePtr e(new QBackendNodePropertyChange(peerId()));
+    auto e = QGeometryChangePtr::create(peerId());
     e->setPropertyName("geometry");
-    // The Frontend element has to perform the clone
-    // So that the objects are created in the main thread
-    e->setValue(QVariant::fromValue(QNodePtr(geometry, &QNodePrivate::nodePtrDeleter)));
+    e->data = std::move(geometry);
     notifyObservers(e);
-    // Maybe we could also send a status to help troubleshoot errors
+
+    // TODO: Maybe we could also send a status to help troubleshoot errors
 }
 
 void GeometryRenderer::unsetDirty()
diff --git a/src/render/geometry/qgeometryrenderer.cpp b/src/render/geometry/qgeometryrenderer.cpp
index 90a3fd662..716417bc5 100644
--- a/src/render/geometry/qgeometryrenderer.cpp
+++ b/src/render/geometry/qgeometryrenderer.cpp
@@ -406,18 +406,12 @@ void QGeometryRenderer::setGeometryFactory(const QGeometryFactoryPtr &factory)
  */
 void QGeometryRenderer::sceneChangeEvent(const Qt3DCore::QSceneChangePtr &e)
 {
-    Q_UNUSED(e);
-    // TODO: Avoid cloning here
-//    Q_D(QGeometryRenderer);
-//    QScenePropertyChangePtr change = qSharedPointerCast<QScenePropertyChange>(e);
-//    if (change->type() == NodeUpdated && change->propertyName() == QByteArrayLiteral("geometry")) {
-//        QNodePtr nodePtr = change->value().value<QNodePtr>();
-//        QGeometry *backendGeometry = static_cast<QGeometry *>(nodePtr.data());
-//        QGeometry *frontendGeometry = static_cast<QGeometry *>(QNode::clone(backendGeometry));
-//        if (frontendGeometry != nullptr)
-//            d->insertTree(frontendGeometry);
-//        setGeometry(frontendGeometry);
-//    }
+    auto change = qSharedPointerCast<QNodePropertyChangeBase>(e);
+    if (change->type() == NodeUpdated && change->propertyName() == QByteArrayLiteral("geometry")) {
+        auto typedChange = qSharedPointerCast<QGeometryChange>(e);
+        auto geometry = std::move(typedChange->data);
+        setGeometry(geometry.release());
+    }
 }
 
 Qt3DCore::QNodeCreatedChangeBasePtr QGeometryRenderer::createNodeCreationChange() const
diff --git a/src/render/geometry/qgeometryrenderer_p.h b/src/render/geometry/qgeometryrenderer_p.h
index d3ef46c4c..3341a7758 100644
--- a/src/render/geometry/qgeometryrenderer_p.h
+++ b/src/render/geometry/qgeometryrenderer_p.h
@@ -54,6 +54,8 @@
 #include <Qt3DCore/private/qcomponent_p.h>
 #include <Qt3DRender/qgeometryrenderer.h>
 #include <Qt3DRender/qgeometryfactory.h>
+#include <Qt3DCore/qbackendnodepropertychange.h>
+#include <memory>
 
 QT_BEGIN_NAMESPACE
 
@@ -91,6 +93,10 @@ struct QGeometryRendererData
     QGeometryFactoryPtr geometryFactory;
 };
 
+class QGeometry;
+typedef Qt3DCore::QTypedBackendNodePropertyChange<std::unique_ptr<QGeometry>> QGeometryChange;
+typedef Qt3DCore::QTypedBackendNodePropertyChangePtr<std::unique_ptr<QGeometry>> QGeometryChangePtr;
+
 } // namespace Qt3DRender
 
 QT_END_NAMESPACE