Five Minute Silverlight 4 Aides-Memoire #1 – Drag and Drop

Build a hierarchical treeview of files and directories dropped from a Windows Explorer window. Requires elevated trust running out of browser to avoid security exceptions when accessing the directory information in the FileInfo objects returned from the e.Data.GetData call.

<Grid x:Name="LayoutRoot" AllowDrop="True" Drop="LayoutRoot_Drop">
    <my:TreeView x:Name="DirectoriesTreeView" Margin="50" Width="500" />
</Grid>

private void LayoutRoot_Drop(object sender, DragEventArgs e)
{
    if (!Application.Current.HasElevatedPermissions  e.Data == null)
        return;

    FileInfo[] fileInfos = e.Data.GetData(DataFormats.FileDrop) as FileInfo[];
    if (fileInfos == null)
        return;
    List<FileInfo> sortedList = new List<FileInfo>(fileInfos);

    sortedList.Sort((x, y) =>
    {
        if (x.Attributes == FileAttributes.Directory && y.Attributes != FileAttributes.Directory)
            return -1;
        if (y.Attributes == FileAttributes.Directory && x.Attributes != FileAttributes.Directory)
            return 1;
        return x.Name.CompareTo(y.Name);
    });

    foreach (FileInfo fileInfo in sortedList)
    {
        var newNode = new TreeViewItem { Header = fileInfo.Name };
        DirectoriesTreeView.Items.Add(newNode);
        if (!fileInfo.Exists)
            ProcessDirectory(fileInfo, newNode);
    }
}

private static void ProcessDirectory(FileSystemInfo fileSystemInfo, TreeViewItem currentNode)
{
    DirectoryInfo directoryInfo = new DirectoryInfo(fileSystemInfo.FullName);

    foreach (FileSystemInfo childFileSystemInfo in directoryInfo.EnumerateFileSystemInfos())
    {
        var newNode = new TreeViewItem { Header = childFileSystemInfo.Name };
        currentNode.Items.Add(newNode);
        if (childFileSystemInfo.Attributes == FileAttributes.Directory)
            ProcessDirectory(childFileSystemInfo, newNode);
    }
}