void ShowPreview(SharpTreeViewItem item, DropPlace place)
{
previewNodeView = item.NodeView;
previewPlace = place;
if (place == DropPlace.Inside)
{
previewNodeView.TextBackground = SystemColors.HighlightBrush;
previewNodeView.Foreground = SystemColors.HighlightTextBrush;
}
else
{
if (insertMarker == null)
{
var adornerLayer = AdornerLayer.GetAdornerLayer(this);
var adorner = new GeneralAdorner(this);
insertMarker = new InsertMarker();
adorner.Child = insertMarker;
adornerLayer.Add(adorner);
}
insertMarker.Visibility = Visibility.Visible;
var p1 = previewNodeView.TransformToVisual(this).Transform(new Point());
var p = new Point(p1.X + previewNodeView.CalculateIndent() + 4.5, p1.Y - 3);
if (place == DropPlace.After)
{
p.Y += previewNodeView.ActualHeight;
}
insertMarker.Margin = new Thickness(p.X, p.Y, 0, 0);
SharpTreeNodeView secondNodeView = null;
var index = flattener.IndexOf(item.Node);
if (place == DropPlace.Before)
{
if (index > 0)
{
secondNodeView = (ItemContainerGenerator.ContainerFromIndex(index - 1) as SharpTreeViewItem).NodeView;
}
}
else if (index + 1 < flattener.Count)
{
secondNodeView = (ItemContainerGenerator.ContainerFromIndex(index + 1) as SharpTreeViewItem).NodeView;
}
var w = p1.X + previewNodeView.ActualWidth - p.X;
if (secondNodeView != null)
{
var p2 = secondNodeView.TransformToVisual(this).Transform(new Point());
w = Math.Max(w, p2.X + secondNodeView.ActualWidth - p.X);
}
insertMarker.Width = w + 10;
}
}
void HidePreview()
{
if (previewNodeView != null)
{
previewNodeView.ClearValue(SharpTreeNodeView.TextBackgroundProperty);
previewNodeView.ClearValue(SharpTreeNodeView.ForegroundProperty);
if (insertMarker != null)
{
insertMarker.Visibility = Visibility.Collapsed;
}
previewNodeView = null;
}
}