WPF Drag and Drop Source Code

Question

Almost all the questions on stackoverflow dealing with drag and drop in WPF refer back to this article. However, the source code for the article is missing. Does anyone have a copy or know where to find a copy?

P.S. My main concern is this line from the article: "There is more code in DragAdorner, but mostly used for positioning the adorner as the drag is happening... please refer to the sample..." I have no idea how he positions the drag adorner.

Answer 1

I have some working code based on the original series of blog posts. The full code is too long to post here; I've posted it to PasteBin.

The code in the DragAdorner is quite simple:

internal sealed class DragAdorner : Adorner
{
   private readonly UIElement _child;
   private readonly double _xCenter;
   private readonly double _yCenter;
   private double _leftOffset;
   private double _topOffset;

   public DragAdorner(UIElement owner, UIElement child, bool useVisualBrush, double opacity) : base(owner)
   {
      if (!useVisualBrush)
      {
         _child = child;
      }
      else
      {
         var size = GetRealSize(child);
         _xCenter = size.Width / 2;
         _yCenter = size.Height / 2;

         _child = new Rectangle
         {
            RadiusX = 3,
            RadiusY = 3,
            Width = size.Width,
            Height = size.Height,
            Fill = new VisualBrush(child)
            {
               Opacity = opacity,
               AlignmentX = AlignmentX.Left,
               AlignmentY = AlignmentY.Top,
               Stretch = Stretch.None,
            },
         };
      }
   }

   protected override int VisualChildrenCount
   {
      get { return 1; }
   }

   public double LeftOffset
   {
      get
      {
         return _leftOffset + _xCenter;
      }
      set
      {
         _leftOffset = value - _xCenter;
         UpdatePosition();
      }
   }

   public double TopOffset
   {
      get
      {
         return _topOffset + _yCenter;
      }
      set
      {
         _topOffset = value - _yCenter;
         UpdatePosition();
      }
   }

   private static Size GetRealSize(UIElement child)
   {
      return child == null ? Size.Empty : child.RenderSize;
   }

   public void UpdatePosition(Point point)
   {
      _leftOffset = point.X;
      _topOffset = point.Y;
      UpdatePosition();
   }

   public void UpdatePosition()
   {
      var adorner = Parent as AdornerLayer;
      if (adorner != null) adorner.Update(AdornedElement);
   }

   protected override Visual GetVisualChild(int index)
   {
      if (0 != index) throw new ArgumentOutOfRangeException("index");
      return _child;
   }

   protected override Size MeasureOverride(Size availableSize)
   {
      _child.Measure(availableSize);
      return _child.DesiredSize;
   }

   protected override Size ArrangeOverride(Size finalSize)
   {
      _child.Arrange(new Rect(_child.DesiredSize));
      return finalSize;
   }

   public override GeneralTransform GetDesiredTransform(GeneralTransform transform)
   {
      var result = new GeneralTransformGroup();
      result.Children.Add(new TranslateTransform(_leftOffset, _topOffset));

      var baseTransform = base.GetDesiredTransform(transform);
      if (baseTransform != null) result.Children.Add(baseTransform);

      return result;
   }
}

Answer 2

E-mailed the author and got a response that he no longer has the source code for the article.