I’ve been wanting to learn COM lately, and not knowing where to start I began in some of the MFC books I have. Admittedly, MFC hides quite a bit of COM complexity, but I figured it would be a good place to get my feet wet without getting scared.

My first test program is called Curvy (Actually, Curvy2 since I restarted it with the doc/view architecture). It’s a curve drawing program. You can use the left mouse button to create points on a curve, the right mouse button closes the curve, and you can change the control points and move the curves.

The fun part was implementing copy & paste. It uses the OLE clipboard and puts both its native format and a bitmap on the clipboard.

The other fun part was implementing OLE Drag & Drop. This took me a few times to get quite right, but the results are spectacular. You can drag shapes within a window as well as to other windows. Holding down the ctrl key will copy the shape instead.

The project is in VS .Net 2005 format, but the code will compile under previous versions of VS.

Click here to download.

Next stop for this? Implement a full OLE server so other programs can host Curvy components inside them!