/// <summary>
/// When overridden in a derived class, participates in rendering operations that are directed by the layout system.
/// The rendering instructions for this element are not used directly when this method is invoked, and are instead preserved for
/// later asynchronous use by layout and drawing.
/// </summary>
/// <param name="drawingContext">The drawing instructions for a specific element. This context is provided to the layout system.</param>
protected override void OnRender(DrawingContext drawingContext)
{
var dropInfo = this.DropInfo;
var visualTargetItem = dropInfo.VisualTargetItem;
if (visualTargetItem != null)
{
var rect = Rect.Empty;
var tvItem = visualTargetItem as TreeViewItem;
if (tvItem != null && VisualTreeHelper.GetChildrenCount(tvItem) > 0)
{
var descendant = VisualTreeExtensions.GetVisibleDescendantBounds(tvItem);
var translatePoint = tvItem.TranslatePoint(new Point(), this.AdornedElement);
var itemRect = new Rect(translatePoint, tvItem.RenderSize);
descendant.Union(itemRect);
translatePoint.Offset(1, 0);
rect = new Rect(translatePoint, new Size(descendant.Width - translatePoint.X - 1, tvItem.ActualHeight));
}
if (rect.IsEmpty)
{
rect = new Rect(visualTargetItem.TranslatePoint(new Point(), this.AdornedElement), VisualTreeExtensions.GetVisibleDescendantBounds(visualTargetItem).Size);
}
drawingContext.DrawRoundedRectangle(null, this.Pen, rect, 2, 2);
}
}
