Allow pointer handlers to be added to QQuick3DModel objects

Mainly it's a matter of removing the assumption that parent() is always
a QQuickItem.  But handlers that have a target property do not know how
to manipulate it when it's not an item; so for example you can use
DragHandler's translation property to manipulate the object, but it
doesn't drag a 3D object by default.

Delivery logic for now is implemented in QQuick3DViewport, because it's
intimately tied to picking, and QQuickDeliveryAgent doesn't really know
anything about QQ3D objects, and the conventional delivery to handlers
in Qt Quick depends on QQuickItemPrivate::handlePointerEvent()
which isn't available in that use case.

Hover events are interfering with DragHnadler (wantsPointerEvent()
returns false, therefore the handler gets deactivated right away).
HoverHandler detects hover but does not detect leave, but that's
probably a matter for the delivery logic to fix.

Change-Id: Id0ec385ce8df3a003f72a6666d16632cef72bbd6
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/quick/handlers/qquickhoverhandler.cpp b/src/quick/handlers/qquickhoverhandler.cpp
index b934940126..020afc647a 100644
--- a/src/quick/handlers/qquickhoverhandler.cpp
+++ b/src/quick/handlers/qquickhoverhandler.cpp
@@ -101,8 +101,10 @@ bool QQuickHoverHandler::event(QEvent *event)
 
 void QQuickHoverHandler::componentComplete()
 {
-    parentItem()->setAcceptHoverEvents(true);
-    QQuickItemPrivate::get(parentItem())->setHasHoverInChild(true);
+    if (auto par = parentItem()) {
+        par->setAcceptHoverEvents(true);
+        QQuickItemPrivate::get(par)->setHasHoverInChild(true);
+    }
 }
 
 bool QQuickHoverHandler::wantsPointerEvent(QPointerEvent *event)