Tutorial 2: Adapting Custom Data

This tutorial shows how to implement the Series interface to return data values directly from application's model objects, instead of extracting them into dedicated lists as parameters for SimpleSeries. The code builds upon Tutorial 1, replacing SimpleSeries instances with the custom series.

1. Declare an enumeration specifying which data value of the model should be returned by a specific series:

C#

enum PriceType
{
    Open,
    Close,
    Low,
    High
};

2. Add a MySeries class that implements Series interface:

C#

class MySeries : Series
{
}

3. Define a reference to the stock-price service results from previous tutorial:

C#

public List<StockPrice> Prices { get; set; }

4. Add a property of the enum type above:

C#

public PriceType PriceType { get; set; }

5. The only constructor we allow must receive a reference to the model data:

C#

public MySeries(List<StockPrice> prices, PriceType priceType)
{
    Prices = prices;
    PriceType = priceType;
}

6. Now implement the interface members, starting with Size:

C#

public int Size => Prices.Count;

7. For the BarChart in this example, we only return one-dimensional data (Y values):

C#

public int Dimensions => 1;

8. GetValue implementation returns the data from specified StockPrice member:

C#

public double GetValue(int index, int dimension)
{
    switch (PriceType)
    {
    case PriceType.Open:
        return Prices[index].Open;
    case PriceType.Close:
        return Prices[index].Close;
    case PriceType.Low:
        return Prices[index].Low;
    case PriceType.High:
        return Prices[index].High;
    }
    return 0;
}

9. SupportedLabels declares X axis labels for one of the series. If each series shows X labels, they would be rendered on separate rows under the axis:

C#

public LabelKinds SupportedLabels =>
    PriceType == PriceType.Open ? LabelKinds.XAxisLabel : LabelKinds.None;

10. GetLabel returns the date as label. Here you could as well return labels to draw inside or above bars, at either axis, or as tooltips:

C#

public string GetLabel(int index, LabelKinds kind)
{
    return Prices[index].Date.ToShortDateString();
}

11. Title strings are displayed inside the legend box:

C#

public string Title => PriceType.ToString();

12. The chart refreshes automatically if this event is raised (not used in this example):

C#

public event EventHandler DataChanged;

13. The charts draw respective data element as highlighted if this returns true:

C#

public bool IsEmphasized(int index)
{
    return false;
}

14. The chart can do some optimizations, such as binary search for viewport clipping, if it knows data values are returned sorted. Return true if data is actually sorted, or you will get incorrect results:

C#

public bool IsSorted(int dimension)
{
    return false;
}

15. Now you can add MySeries instance to the chart.Series assignments:

C#

// a series of daily opening prices
chart.Series.Add(
    new MySeries(stockPrices, PriceType.Open));

// a series of daily closing prices
chart.Series.Add(
    new MySeries(stockPrices, PriceType.Close));

// a series of daily min prices
chart.Series.Add(
    new MySeries(stockPrices, PriceType.Low));

// a series of daily max prices
chart.Series.Add(
    new MySeries(stockPrices, PriceType.High));

The chart will look as in previous tutorial, but data values are no longer copied to new arrays, and are returned directly from the model objects: