A Silverlight Scale Chord Calculator (SilverKeys Part 1)

One hobby I have is music production (based around a Pro Tools LE 8 setup) and recently I've been learning some music theory. I have created a cheat sheet which is on my wall to assist with working out scale degrees, etc. Why do it by hand when a computer can do it for you, eh? Thought this would make a good Silverlight project as ideally I'd like to be able to visualise a chord on a piano keyboard or a guitar fretboard.

Functionality would be something like:

  • Choose a scale - Major or (natural) Minor;
  • Choose a scale root note (as a dropdown or better by directly interacting with piano keyboard);
  • Show all the notes in the scale (initially visualised on piano keyboard);
  • Show the scale degrees and chords for the given key;
  • Show the common chord progressions in the key;
Future additions:
  • Add guitar fretboard vis;
  • Add harmonic minor scales;
  • Add modal functionality;
  • Play sound samples of notes & chords;

The application will be a standalone client app, i.e. no WCF backend services, etc. It will be designed using TDD and using Expression Blend where appropriate (with the Blend service pack it extends the trial period to 60 days). As I can't think of a good name off the top of my head, i'll call the app SilverKeys...


System.ExecutionEngineException in Silverlight

Check your resource styles have specified a target type, e.g. TargetType="TextBlock": the exception that is thrown is System.ExecutionEngineException but with no inner exception details it doesn't offer much help. The solution will also build correctly without even a XAML warning...


Design Pattern for Silverlight 2

It seems the Model-View-ViewModel (MVVM) is the preferred pattern at present for implementing cleanly separated SL apps (& WPF client apps). Aims to increase testability and leverage data-binding in XAML to implement the View part of the pattern. The Model is responsible for accessing data (e.g. WCF service, REST, etc) and passing it to the ViewModel (which holds state and provides operations to the View)- the View then binds to objects in the ViewModel class. A view has a reference to a Model interface rather than a concrete implementation, this allows testing of the Model in isolation. We could implement the ViewModel as an interface or for testing purpose just build a stub Model and pass that the the ViewModel (going the whole hog you could use dependency injection such as Unity for Silverlight or Ninject to wire the parts together).

More info on MVVM: