从WPF listview拖动多个项目

Question

我有一个列表视图,显示目录中的文件.
用户可以将列表视图中的每个项目拖动到文件夹/桌面,并在那里复制关联的文件.
这很好用.问题是 - 我想对多个项目这样做 - 因此用户可以选择多个listviewitems并将它们拖放并复制在一起.ListView设置为SelectedMode = Multiple-但它不会复制所有选定的项目.这是我的代码:

    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[1];
            files[0] = "C:\\Users\\MyName\\Music\\My playlist\\" + FileView.SelectedValue.ToString();
            string dataFormat = DataFormats.FileDrop;
            DataObject dataObject = new DataObject(dataFormat, files);
            DragDrop.DoDragDrop(this.FileView, dataObject, DragDropEffects.Copy);
        } 
    }

谢谢!

Answer 1

这里的问题是你使用SelectedValue进行多选,所以你得到一个文件.你想要的是更像这样的东西:

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 2

 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>());

    }

在MouseMove上还原

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