Sub classing a C# window in a DLL created using embedded VC++

One of the requirements for a PDA product was to subclass a window in a dll which is created in a C# application.

GUI for the same was developed using C# and for recording functionality they have a dll created using embedded VC++. Now, the waveform-audio input device sends a notification message to the specified window, but the question was how to get a window handle which is created in C# application so that it can be passed as a parameter for waveInOpen function? We need to somehow pass the window handle to dll so that dll can subclass the window and the messages can be processed in the dll itself.

This is what I did and it seems to be working fine.

First of all the functions implemented in dll are called using dllimport in the C# application. You need to write the following code to access the functions exported from this dll (Recrdr.dll). I have put all these functions in a class named Wrapper.

I added one more function in the dll which will accept the window handle of a C# window. I imported the same in the C# application.

Now, I need to pass the windows handle to this function (Please note that this.Handle is not supported in .Net Compact framework). Then how do we do this? Well, again we need to call a windows api for getting the window handle. For that, you need to import the windows dll named coredll.dll which implements GetForegroundWindow function.