Sorting library items in subfolders by parent folders

I'm trying to create a web part that sorts items in subfolders according to their parent folders. I changed the Folder Scope to show all files and all subfolders, but any sorting method I use in SPD lists all the subfolders first and then all the files. How can I sort the library to show a folder name, then all the items in the folder, and another folder, than all that folder's items, and so forth?