SuperMap.WinRT.Mapping.ElementsLayer.Invalidate C# (CSharp) Method

        private void Invalidate()
        {
            if (!this.isInvalidated)
            {
                CompositionTarget.Rendering += new EventHandler<object>(this.CompositionTarget_Rendering);
                this.isInvalidated = true;
            }
        }
        private void CompositionTarget_Rendering(object sender, object e)