Set QObject parent immediately and defer backend notifications

This is needed to ensure that subtrees created up front before the
aspect engine starts all get added to the scene. This restores correct
behavior in cylinder-cpp.

With this change all QNode data is correctly set up synchronously
upon construction or via setParent(). That is, the scene and arbiter
are properly propagated from the parent and the scene is made
aware of mappings.

Notfications to the backend are deferred until the QNode is fully
constructed.

Unit tests updated to match this and documentation expanded to
capture the details.

Change-Id: Ic6b3b46240fdccd67f9526fc3219aac8b7f350f3
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/core/nodes/qnode_p.h b/src/core/nodes/qnode_p.h
index 231d1ff94..9731138c1 100644
--- a/src/core/nodes/qnode_p.h
+++ b/src/core/nodes/qnode_p.h
@@ -70,6 +70,8 @@ class QT3DCORE_PRIVATE_EXPORT QNodePrivate : public QObjectPrivate, public QObse
 public:
     QNodePrivate();
 
+    void init(QNode *parent);
+
     void setScene(QScene *scene);
     QScene *scene() const;
 
@@ -97,6 +99,8 @@ public:
     static void nodePtrDeleter(QNode *q);
 
 private:
+    void notifyCreationChange();
+    void _q_notifyCreationAndChildChanges();
     void _q_addChild(QNode *childNode);
     void _q_removeChild(QNode *childNode);
     void _q_setParentHelper(QNode *parent);