My Prism Journey (Part 1)

I’m not going to describe what Prism is because you can just do a search :)  I’m going to post my experiences in trying to leverage the Prism libraries to create a modular application.  The tutorials that come with the library are very helpful so people should definitely read the chm file for help.  I’m also trying to be as MVVM as possible so hopefully I don’t completely mangle my application.

One of the components that I’m adding to my application requires COM Interop… yay.  I did the obligatory aximp call on my ActiveX component, but for some reason I got a file not found exception whenever I tried to access the component at runtime.  Adding the references created by aximp didn’t seem to work.

I had to actually create a new WinForms control library, add the component to my toolbox, drag the component to the control, and then I was able to access the component at runtime.  No worries, I just copied the interop dlls and placed them in a folder so that those can be used instead of the aximp generated ones.

To include interop ActiveX components in your WPF application, you need to host the ActiveX component in a WinForms control.  No problem, add WindowsFormsIntegration so you can use the WindowsFormHost control in your WPF app/control.  You can then add the component to the WindowsFormHost.Child and it will display.  Pretty straight forward…

After getting the above sorted out, I got my interop control to display in the specified region in my shell.  However, it was displaying incorrectly… I set the ActiveX.Dock = Fill, but it wasn’t filling the region.  I sat there for a good hour or so trying to figure this one out… No matter what I did, it just wouldn’t fill the damn region. 

I then decided to create a little test program to see where the issue could possibly be.  I added a WindowsFormHost and a reference to the ActiveX component.  It filled fine!  Ok, maybe it’s because the region in my application is wrapped with a Tabcontrol.  I wrapped the WindowsFormHost with the TabControl and it still filled correctly.  Wait, to add a region to your shell, you need to specify what the region is hosted in, which is either an ItemsControl or ContentControl. 

It turns out that I used ItemsControls to host my regions (because the tutorial used those as well).  I then tried switching my region hosts to ContentControls and now my ActiveX component fills as it should… Sheesh.