WPF: Drag and drop virtual files into Windows explorer

Question

I'm developing an application similar to dropbox and i show the remote files on a WPF listview. I want to drag those elements and drop it into windows explorer. I've seen code like this:

var dataObject = new DataObject(DataFormats.FileDrop, files.ToArray());
dataObject.SetData(DataFormats.StringFormat, dataObject);
DoDragDrop(dataObject, DragDropEffects.Copy);

But as you may think, those file are not at the local system yet, before copiying them I need to connect to server, donwload and unzip the files. Like a ftp client does.

I dont how to do it but i was wondering if there is any "drop" event or similiar that i can handle.

Thanks!

Answer 1

This snippet:

var virtualFileDataObject = new VirtualFileDataObject(
                // BeginInvoke ensures UI operations happen on the right thread
                (vfdo) => Dispatcher.BeginInvoke((Action)(() => BusyScreen.Visibility = Visibility.Visible)),
                (vfdo) => Dispatcher.BeginInvoke((Action)(() => BusyScreen.Visibility = Visibility.Collapsed)));

            // Provide a virtual file (downloaded on demand), its URL, and descriptive text
            virtualFileDataObject.SetData(new VirtualFileDataObject.FileDescriptor[]
            {
                new VirtualFileDataObject.FileDescriptor
                {
                    Name = "DelaysBlog.xml",
                    StreamContents = stream =>
                        {
                            using(var webClient = new WebClient())
                            {
                                var data = webClient.DownloadData("http://blogs.msdn.com/delay/rss.xml");
                                stream.Write(data, 0, data.Length);
                            }
                        }
                },
            });
            virtualFileDataObject.SetData(
                (short)(DataFormats.GetDataFormat(CFSTR_INETURLA).Id),
                Encoding.Default.GetBytes("http://blogs.msdn.com/delay/rss.xml\0"));
            virtualFileDataObject.SetData(
                (short)(DataFormats.GetDataFormat(DataFormats.Text).Id),
                Encoding.Default.GetBytes("[The RSS feed for Delay's Blog]\0"));

            DoDragDropOrClipboardSetDataObject(e.ChangedButton, TextUrl, virtualFileDataObject, DragDropEffects.Copy);

Using the class linked should work. . Very nice and easy solution.

Answer 2

http://pavanpodila.spaces.live.com/blog/cns!9C9E888164859398!190.entry http://pavanpodila.spaces.live.com/blog/cns!9C9E888164859398!199.entry http://pavanpodila.spaces.live.com/blog/cns!9C9E888164859398!225.entry

See this series of articles. This should help you get started.

EDIT: See this for an amplementation of the dragsourceadvisor

 internal class ImagesViewPanelDragSourceAdvisor : IDragSourceAdvisor
 {
     private FrameworkElement _dragSource;

     public DependencyObject DragSource
     {
         get
         {
             return _dragSource;
         }
         set
         {
             _dragSource = value as FrameworkElement;
         }
     }

     public DependencyObject DragObject { get; set; }

     public DragDropEffects GetDragDropEffects()
     {
         DragDropEffects effects = DragDropEffects.None;

         FrameworkElement frameworkObj = DragObject as FrameworkElement;

         if (frameworkObj != null && frameworkObj.DataContext is ImageViewModel)
         {
             effects = DragDropEffects.Copy;
         }

         return effects;
     }

     public IDataObject GetDragDataObject()
     {
         Debug.Assert(GetDragDropEffects() != DragDropEffects.None);

         ImagesViewModel imagesVM = (FrameworkElement)DragSource).DataContext  as ImagesViewModel;

         StringCollection fileList = new StringCollection();

         foreach (ImageViewModel imageVM in imagesVM.Items.Where(imageVM => imageVM.IsSelected))
         {
             fileList.Add(imageVM.ImagePath);
         }

         Debug.Assert(fileList.Count > 0);

         DataObject dataObj = new DataObject();

         dataObj.SetFileDropList(fileList);

         return dataObj;
     }

     public void FinishDrag(DragDropEffects finalEffect)
     {
     }