Copyright (C) 2017-2018 David Capello
Distributed under MIT license
On Windows we have to create a COM server in a DLL to provide
thumbnails. The DLL must provide an
IThumbnailProvider
implementation. Our implementation is in
desktop::ThumbnailHandler class, the most
interesting member function is
ThumbnailHandler::GetThumbnail(),
which should return a HBITMAP of the thumbnail.
If you distribute your app in an installer remember to use
regsvr32.exe to register your DLL which will call your DLL's
DllRegisterServer(), a function that must
create registry keys to associate your file type extension with
your thumbnail handler.
More information in the MSDN.