Relative Strength Index

Public Class DataService
    Private _companies As New List(Of Company)()
    Private _cache As New Dictionary(Of String, List(Of Quote))()
    Private Sub New()
        _companies.Add(New Company() With {
            Key.Symbol = "box",
            Key.Name = "Box Inc"
        })
        _companies.Add(New Company() With {
            Key.Symbol = "fb",
            Key.Name = "Facebook"
        })
    End Sub
    Public Function GetCompanies() As List(Of Company)
        Return _companies
    End Function
    Public Function GetSymbolData(symbol As String) As List(Of Quote)
        If Not _cache.Keys.Contains(symbol) Then
            Dim path As String = String.Format("FinancialChartExplorer.Resources.{0}.json", symbol)
            Dim stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(path)
            Dim ser = New DataContractJsonSerializer(GetType(Quote()))
            Dim data = DirectCast(ser.ReadObject(stream), Quote())
            _cache.Add(symbol, data.ToList())
        End If
        Return _cache(symbol)
    End Function
    Shared _ds As DataService
    Public Shared Function GetService() As DataService
        If _ds Is Nothing Then
            _ds = New DataService()
        End If
        Return _ds
    End Function
End Class

public class DataService
{
    List<Company> _companies = new List<Company>();
    Dictionary<string, List<Quote>> _cache = new Dictionary<string, List<Quote>>();
    private DataService()
    {
        _companies.Add(new Company() { Symbol = "box", Name = "Box Inc" });
        _companies.Add(new Company() { Symbol = "fb", Name = "Facebook" });
    }
    public List<Company> GetCompanies()
    {
        return _companies;
    }
    public List<Quote> GetSymbolData(string symbol)
    {
        if (!_cache.Keys.Contains(symbol))
        {
            string path = string.Format("FinancialChartExplorer.Resources.{0}.json", symbol);
            var stream = Assembly.GetExecutingAssembly().GetManifestResourceStream(path);
            var ser = new DataContractJsonSerializer(typeof(Quote[]));
            var data = (Quote[])ser.ReadObject(stream);
            _cache.Add(symbol, data.ToList());
        }
        return _cache[symbol];
    }
    static DataService _ds;
    public static DataService GetService()
    {
        if (_ds == null)
            _ds = new DataService();
        return _ds;
    }
}

Partial Public Class Indicators
    Inherits UserControl
    Private dataService As DataService = DataService.GetService()
    Private rsi As New RSI() With {
        Key.SeriesName = "RSI"
    }
    Public Sub New()
        InitializeComponent()
    End Sub
    Public ReadOnly Property Data() As List(Of Quote)
        Get
            Return dataService.GetSymbolData("box")
        End Get
    End Property
    Public ReadOnly Property IndicatorType() As List(Of String)
        Get
            Return New List(Of String)() From {
                "Relative Strength Index"
            }
        End Get
    End Property
    Private Sub OnIndicatorTypeSelectionChanged(sender As Object, e As SelectionChangedEventArgs)
        Dim ser As FinancialSeries = Nothing
        If cbIndicatorType.SelectedIndex = 0 Then
            ser = rsi
        End If
        If ser IsNot Nothing AndAlso Not indicatorChart.Series.Contains(ser) Then
            indicatorChart.BeginUpdate()
            indicatorChart.Series.Clear()
            indicatorChart.Series.Add(ser)
            indicatorChart.EndUpdate()
        End If
    End Sub
    Private Sub OnFinancialChartRendered(sender As Object, e As C1.WPF.Chart.RenderEventArgs)
        If indicatorChart IsNot Nothing Then
            indicatorChart.AxisX.Min = DirectCast(financialChart.AxisX, IAxis).GetMin()
            indicatorChart.AxisX.Max = DirectCast(financialChart.AxisX, IAxis).GetMax()
        End If
    End Sub
End Class

public partial class Indicators : UserControl
{
    DataService dataService = DataService.GetService();
    RSI rsi = new RSI() { SeriesName = "RSI" };
    public Indicators()
    {
        InitializeComponent();
    }
    public List<Quote> Data
    {
        get
        {
            return dataService.GetSymbolData("box");
        }
    }
    public List<string> IndicatorType
    {
        get
        {
            return new List<string>()
            {
                "Relative Strength Index",
            };
        }
    }
    void OnIndicatorTypeSelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        FinancialSeries ser = null;
        if (cbIndicatorType.SelectedIndex == 0)
            ser = rsi;
        if (ser != null && !indicatorChart.Series.Contains(ser))
        {
            indicatorChart.BeginUpdate();
            indicatorChart.Series.Clear();
            indicatorChart.Series.Add(ser);
            indicatorChart.EndUpdate();
        }
    }
    void OnFinancialChartRendered(object sender, C1.WPF.Chart.RenderEventArgs e)
    {
        if (indicatorChart != null)
        {
            indicatorChart.AxisX.Min = ((IAxis)financialChart.AxisX).GetMin();
            indicatorChart.AxisX.Max = ((IAxis)financialChart.AxisX).GetMax();
        }
    }
}