constraint.Apply();
// Visibility constraint
constraint = Constraint::New< bool >( actor, Actor::Property::VISIBLE, DepthVisibilityConstraint( itemId, mImpl->mNumberOfColumns, mImpl->mNumberOfRows*0.5f, itemId % mImpl->mNumberOfColumns ) );
constraint.AddSource( ParentSource( Toolkit::ItemView::Property::LAYOUT_POSITION ) );
constraint.Apply();
// Visibility constraint
constraint = Constraint::New< bool >( actor, Actor::Property::VISIBLE, DepthVisibilityConstraint( itemId, mImpl->mNumberOfColumns, mImpl->mNumberOfRows*0.5f, itemId % mImpl->mNumberOfColumns ) );
constraint.AddSource( ParentSource( Toolkit::ItemView::Property::LAYOUT_POSITION ) );