Drag multiple items from WPF listview

Question

I have a listview that displays files from a directory.
The user can drag each item in the listview to a folder/ the desktop and the associated file is copied there.

Answer 1

I'd like to point out an small error in the code

    Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance &&
    Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance)

should be

    Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
    Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance)

Otherwise a straight Horizontal or Vertical will do nothing. Chances of that happening are small, but still..

Answer 2

The problem here is that you are using SelectedValue for a multiselect, so you get one file. What you want is something more like this:

private void FileView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    this.start = e.GetPosition(null);
}

private void FileView_MouseMove(object sender, MouseEventArgs e)
{
    Point mpos = e.GetPosition(null);
    Vector diff = this.start - mpos;

    if (e.LeftButton == MouseButtonState.Pressed &&
        (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
         Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance)
    )
    {
        if (this.FileView.SelectedItems.Count == 0)
            return;

        // right about here you get the file urls of the selected items.  
        // should be quite easy, if not, ask.  
        string[] files = new String[FileView.SelectedItems.Count];
        int ix = 0;
        foreach (object nextSel in FileView.SelectedItems)
        {
            files[ix] = "C:\\Users\\MyName\\Music\\My playlist\\" + nextSel.ToString();
            ++ix;
        }
        string dataFormat = DataFormats.FileDrop;
        DataObject dataObject = new DataObject(dataFormat, files);
        DragDrop.DoDragDrop(this.FileView, dataObject, DragDropEffects.Copy);
    } 
}

Answer 3

 private List<object> _selItems = new List<object>();
    private void FileView_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        this._start = e.GetPosition(null);
        _selItems.Clear();
        _selItems.AddRange(FileView.SelectedItems.Cast<object>());

    }

restore on MouseMove

foreach (object selItem in _selItems)
            {
                if (!FileView.SelectedItems.Contains(selItem))
                    FileView.SelectedItems.Add(selItem);
            }