Unable to drag file to Windows Explorer from a WPF ListView

问题

I am trying to drag a ListView item and drop it as a copy of file from the location stored in that ListView item. I am successfully getting the location from the ListView item when I start dragging but unable to signal Operating System to copy that file to the specified location.

    private Point start;
    ListView dragSource = null;
    private void files_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        this.start = e.GetPosition(null);

        ListView parent = (ListView)sender;
        dragSource = parent;
        object data = GetDataFromListBox(dragSource, e.GetPosition(parent));
        Hide();
        if (data != null)
        {
            string dataStr = ((UserData)data).Data.ToString();
            string filepath = new System.IO.FileInfo(dataStr).FullName;
            DataObject fileDrop = new DataObject(DataFormats.FileDrop, filepath);
            DragDrop.DoDragDrop((ListView)sender, fileDrop, DragDropEffects.Copy);
        }
    }
    private static object GetDataFromListBox(ListView source, Point point)
    {
        UIElement element = source.InputHitTest(point) as UIElement;
        if (element != null)
        {
            object data = DependencyProperty.UnsetValue;
            while (data == DependencyProperty.UnsetValue)
            {
                data = source.ItemContainerGenerator.ItemFromContainer(element);

                if (data == DependencyProperty.UnsetValue)
                {
                    element = VisualTreeHelper.GetParent(element) as UIElement;
                }

                if (element == source)
                {
                    return null;
                }
            }

            if (data != DependencyProperty.UnsetValue)
            {
                return data;
            }
        }

        return null;
    }

The second method GetDataFromListBox() I found on one of the SO questions' answer. This method extracts the correct data from the ListBox or ListView.

I am new to WPF. Please tell me what I am missing?

回答1:

Finally, I found a solution here: http://joyfulwpf.blogspot.in/2012/06/drag-and-drop-files-from-wpf-to-desktop.html

The solution was to assign file drop list using SetFileDropList() method, instead of inside DataObject's constructor. Following is my modified working code:

ListView parent = (ListView)sender;
object data = parent.SelectedItems;

System.Collections.IList items = (System.Collections.IList)data;
var collection = items.Cast<UserData>();
if (data != null)
{
    List<string> filePaths = new List<string>(); 
    foreach (UserData ud in collection)
    {
        filePaths.Add(new System.IO.FileInfo(ud.Data.ToString()).FullName);
    }
    DataObject obj = new DataObject();
    System.Collections.Specialized.StringCollection sc = new System.Collections.Specialized.StringCollection();
    sc.AddRange(filePaths.ToArray());
    obj.SetFileDropList(sc);
    DragDrop.DoDragDrop(parent, obj, DragDropEffects.Copy);
}

来源：https://stackoverflow.com/questions/32725514/unable-to-drag-file-to-windows-explorer-from-a-wpf-listview

标签

.net

wpf

listview

mouseevent