What a wonderful world

Recently I read a lot about the M-V-VM pattern and I wanted to try it out. So I started small with a WPF-application implementing a listview showing some events related to sleep medicine. I’ve created a simple model with a collection of various data. This model is the data-provider for a ViewModel which is databind to this view:

So far, so good; worked pretty easy. I then read something about the graphical ability of WPF, which should be very bad in displaying a lot of graphical objects. Again, I wrote a sleep-medical-application, but this time showing some random biosignals with events:

The problem here was the very long signal build of thousands of Polyline-segments. And indeed, this brought WPF to its knees. You can’t show some signals with the pure use of WPF-technology. I instead used GDI+ inside of a Canvas-element for the signal and the VirtualCanvas-technique for the events (read here about it). With that I managed to preserve databinding on the modifiable objects (the events): you can move them around and change their duration by dragging their border.

In a second step, I combined the model of the ListView with that of the biosignals and injected it into its ViewModel. Of course, every ViewModel is being unittested – what a wonderful world: