Snap-In Interface Technology + Embedded MFC GUI into ATL Server DLL

Thursday Feb 24th 2000 by Steve Bryndin

Snap-In Interface Technology + Embedded MFC GUI into ATL Server DLL

Web site

This code in large borrowed from an article and code sample by Steve Zimmerman "Create Apps That Are Easily Extensible with Our Smart "Snap-Ins" Methodology".   Its been updated to work with ATL 3.0 and VC 6.0, plus a few extra modifications and demonstartions of the coolest technologies :).

To see this sample code in action run the ComSnapin.exe. Your screen will look like this:

It has only 4 menu items: File; Edit; View; and Help.

Now run register.bat located in SnapinOne\ReleaseMinSize directory. This batch file will register SnapinOne.dll with the system. Run ComSnapin.exe again. Your screen should look like this:

There ia a new menu item: Snapin Commands. If you click on the menu item a Doc-View window will popup. This Doc/view framework is entirely confined inside SnapinOne.dll which is a ATL dll server.

If you run unregister.bat which will unregister SnapinOne.dll and excute program again you'll see that the menu item gone.

SnapinOne.dll can communicate with parent application via callback interfaces and obtain from it whatever information it tries to digest.

This gives your "Snapin" enabled parent program virtualy unlimited scalability.


  1. Create a regular MFC exe application framework with App wizard.
  2. Include in your project files: ISnapin.h, ISnapinCallbacks.h, SnapFrm.cpp, SnapFrm.h,   SnapIn.cpp, SnapIn.h.
  3. Derive CMainFrame class from CSnapInFrame instead of CFrameWnd (or CMDIFrameWnd). Easiest way would to add thisl line right above CMainFrame delaration:  #define CFrameWnd CSnapInFrame
  4. Your application is now fully Snap-In ready!

Snap In:

  1. Create a ATL COM Project with ATL App Wizard.  Add it to a current workspace Select it to be a DLL with MFC support.
  2. Add ATL class to this project (for instance CSnapinOne).
  3. Replace base ISnapinOne to ISnapIn, so the class is derived from ISnapIn interface instead.


Download compiled demo - 11 Kb
Download source code for demo project - 63 Kb
Mobile Site | Full Site
Copyright 2017 © QuinStreet Inc. All Rights Reserved