BaconographyWP8.Common.ReorderListBox.FindViewLastIndex C# (CSharp) Method

        private int FindViewLastIndex(int firstIndex)
        {
            int lastIndex = firstIndex;

            GeneralTransform scrollViewerTransform = this.scrollViewer.TransformToVisual(
                Application.Current.RootVisual);
            Rect scrollViewerRect = scrollViewerTransform.TransformBounds(
                new Rect(new Point(0, 0), this.scrollViewer.RenderSize));

            while (lastIndex < this.Items.Count - 1)
            {
                ReorderListBoxItem itemContainer = (ReorderListBoxItem)
                    this.ItemContainerGenerator.ContainerFromIndex(lastIndex + 1);
                if (itemContainer == null)
                {
                    break;
                }

                GeneralTransform itemTransform = itemContainer.TransformToVisual(
                    Application.Current.RootVisual);
                Rect itemRect = itemTransform.TransformBounds(new Rect(new Point(0, 0), itemContainer.RenderSize));
                itemRect.Intersect(scrollViewerRect);
                if (itemRect == Rect.Empty)
                {
                    break;
                }

                lastIndex++;
            }

            return lastIndex;
        }