Rx Compass Smoothing Example for Windows Phone

Companion blog post: http://factormystic.net/blog/using-reactive-extensions-to-smooth-compass-data-in-windows-phone

Reactive Extensions at work:

Observable.FromEvent<SensorReadingEventArgs<CompassReading>>(compass, "CurrentValueChanged")
          .BufferWithTime(TimeSpan.FromSeconds(2))
          .Select(headings => headings.Select(e => e.EventArgs.SensorReading.TrueHeading).Sum() / headings.Count())
          .ObserveOnDispatcher()
          .Subscribe(heading => this.ArrowRotation.Angle = 360 - heading);

Rotates the compass arrow:

<Image Stretch="None" Source="compass.arrow.dark.png" RenderTransformOrigin="0.5,0.5">
    <Image.RenderTransform>
        <RotateTransform x:Name="ArrowRotation" CenterX="0.5" CenterY="0.5" />
    </Image.RenderTransform>
</Image>