Asynchronous Drag and Drop to Windows Explorer

Question

Question:

I need a DragAndDrop solution to download a file on drop in a folder of Windows Explorer for C# & .NET 4.0. It should not be necessary to have the file on the computer. The file will be big enough that the drag-time won't be enough to get the download done. I have found various questions, even accepted answers, but nothing that works. The very closest thing to something working is this demo project:

http://blogs.msdn.com/b/delay/archive/2009/11/16/creating-something-from-nothing-and-knowing-it-developer-friendly-virtual-file-implementation-for-net-refined.aspx

How to implement this code to download a file as part of the action of putting it to the drop place in Windows Explorer?

Answer 1

Web browsers solve this problem every day. Simplifying their model a little, do this:

1. Make a little program that performs your download given appropriate command line parameters. This little program should pop up a window with a progress bar and a cancel button.

2. Spawn this second program whenever the user "drops" something. This program will create the target file immediately and start filling it with data. It will maintain appropriate locks on the file until it is done downloading, at which point the "downloader" will exit.

If you're going to keep the "downloader" threads in the originating program, you will need some kind of download manager so that the user can get appropriate feedback on their downloads.

Answer 2

Okay, as Yahia said in the comments it's not possible without a proper shell extension for the different versions of Windows and .NET. You might have luck with the link I posted, but for me it crashes the Explorer and the developer thinks it works fine.

My honest opinion is with only .NET you can only do it with a FileSystemWatcher via copying special .temp-files, watching where they land, doing your task and replacing the .temp files when your task is done. Sad Windows.