从 WPF 列表视图中拖动多个项目

问题描述

我有一个显示目录中文件的列表视图.
用户可以将列表视图中的每个项目拖动到文件夹/桌面，并将相关文件复制到那里.
这工作正常.问题是 - 我想为多个项目这样做 - 所以用户可以选择多个 listviewitems 并将它们拖动并复制在一起.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:

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.
This works fine. The problem is- I want to do so for multiple items- so the user can select multiple listviewitems and drag and copy them together.The ListView is set to SelectedMode=Multiple- but it doesn't copy all of the selected items.Here's my code:

    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！

推荐答案

这里的问题是您使用 SelectedValue 进行多选，所以您得到一个文件.你想要的是更像这样的东西:

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);
    }
}

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