Drag & Drop directly from Outlook in web app [duplicate]

Answer 1

You can write a browser helper (for IE) in C++ or Delphi that retrieves the current drag/drop handler from IE and installs its own handler. When a message is dragged from Outlook, you can save it to a temp folder, then invoke the original drag/drop handler. After the handler returns, the temporary file can be deleted.

I have done this in the past, and it works fine. You might want to looks at the Google Gears source code (no longer supported) that intercepts drag/drop in IE.

Answer 2

Outlook uses the CFSTR_FILECONTENTS and CFSTR_FILEDESCRIPTOR formats that many applications do not understand. My solution for this problem uses an Outlook Add-in to intercept the D&D and convert the proprietary format into a usual file drop (CF_HDROP).

The Add-in replaces the DoDragDrop function pointer in the import table of OLE32.DLL with a wrapper function (inside Outlook's memory address space). The wrapper converts the D&D data and calls the original function.

This article describes how to hook into an import table. Outlook's D&D stream format is explained here. The stream data has to be written into (temp) files in order to provide a simple CF_HDROP.