WPF - Drag-drop - Adorner disappers outside the control

Question

I'm using WPF to create two ListViews and implement drag-drop functionality. (both intra-listview and inter-listview)

I found an interesting post here which does that.

However, there is a problem. When I drag a listviewitem from listView1, I see the adorner (the ghost image) only inside listView1. When I want to drop the listviewItem on ListView2, I must see the adorner there as well. Basically, the adorner appears only on the listView from which the drag operation started. Once it is outside the listView, it disappears.

I have done a bit of research and could not find a way to make the adorner visible outside the control from which the drag was initiated.

Can anyone help me with some suggestions?

Answer 1

Wire up the GiveFeedback event to update the adorner location beyond the listview. Updated ListView property from the example and method below (and in the listview_DragLeave method you won't want to collapse the adorner):

    /// <summary>
    /// Gets/sets the ListView whose dragging is managed.  This property
    /// can be set to null, to prevent drag management from occuring.  If
    /// the ListView's AllowDrop property is false, it will be set to true.
    /// </summary>
    public ListView ListView
    {
        get { return listView; }
        set
        {
            if( this.IsDragInProgress )
                throw new InvalidOperationException( "Cannot set the ListView property during a drag operation." );

            if( this.listView != null )
            {
                #region Unhook Events

                this.listView.PreviewMouseLeftButtonDown -= listView_PreviewMouseLeftButtonDown;
                this.listView.PreviewMouseMove -= listView_PreviewMouseMove;
                this.listView.DragOver -= listView_DragOver;
                this.listView.DragLeave -= listView_DragLeave;
                this.listView.DragEnter -= listView_DragEnter;
                this.listView.GiveFeedback -= listView_GiveFeedback;
                this.listView.Drop -= listView_Drop;

                #endregion // Unhook Events
            }

            this.listView = value;

            if( this.listView != null )
            {
                if( !this.listView.AllowDrop )
                    this.listView.AllowDrop = true;

                #region Hook Events

                this.listView.PreviewMouseLeftButtonDown += listView_PreviewMouseLeftButtonDown;
                this.listView.PreviewMouseMove += listView_PreviewMouseMove;
                this.listView.DragOver += listView_DragOver;
                this.listView.DragLeave += listView_DragLeave;
                this.listView.DragEnter += listView_DragEnter;
                this.listView.GiveFeedback += listView_GiveFeedback;
                this.listView.Drop += listView_Drop;

                #endregion // Hook Events
            }
        }
    }

    void listView_GiveFeedback(object sender, GiveFeedbackEventArgs e)
    {
        if (this.ShowDragAdornerResolved)
            this.UpdateDragAdornerLocation();
    }