How to create a simple Pie chart using Extended WPF Toolkit

Question

I'm fairly new to C# development. I'm trying to create a simple Pie chart using Visual Studio, C# and Extended WPF Toolkit. The code that follows is a part of a dll i'm trying to build (plug in for Revit). I installed Extended WPF Toolkit using NuGet. I was not able to find any tutorial or examples, so i tried to put up the code from some pieces i found on differnt online sources. At the moment, i have

xmlns:xctk="http://schemas.xceed.com/wpf/xaml/toolkit"

<Grid Grid.Row="1">
        <xctk:Pie x:Name="foobar"
                  DataContext="{Binding PieCollection, UpdateSourceTrigger=PropertyChanged}" >
        </xctk:Pie>
    </Grid>

and

public class PiePoint
{
    public string Name { get; set; }
    public Int16 Share { get; set; }
}

public class CompareToMultiLODViewModel : INotifyPropertyChanged
{
private ObservableCollection<PiePoint> _pieCollection;

    public ObservableCollection<PiePoint> PieCollection
    {
        get { return _pieCollection; }
        set { _pieCollection = value; OnPropertyChanged("PieCollection"); }
    }
public CompareToMultiLODViewModel()
    {
        CompareToMultiLODBtnCommand = new MRCommand(this);

        PieCollection = new ObservableCollection<PiePoint>();
        PieCollection.Add(new PiePoint { Name = "Mango", Share = 10 });
        PieCollection.Add(new PiePoint { Name = "Banana", Share = 36 });
    }

    private PropertyChangedEventHandler _PropertyChanged;

    event PropertyChangedEventHandler INotifyPropertyChanged.PropertyChanged
    {
        add
        {
            //((INotifyPropertyChanged)PieCollection).PropertyChanged += value;
            _PropertyChanged += value;
        }

        remove
        {
            //((INotifyPropertyChanged)PieCollection).PropertyChanged -= value;
            _PropertyChanged -= value;
        }
    }

    private void OnPropertyChanged(string PropertyName)
    {
        _PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));
    }

The code behind xaml is

    public partial class CompareToMultiLOD : Page
{
    public CompareToMultiLOD()
    {
        InitializeComponent();

        DataContext = new CompareToMultiLODViewModel();
    }

I do not know if it's relevant, but when debugging i see that DataContext is assigned before the PieCollection is created, and then OnPropertyChanged is triggered once, on PieCollection initialization. PropertyChanged seems to be triggered once (which i do not understand, since i add two values).

I am not sure that ViewModel is the right place to store data that Pie chart uses, but i placed it there temporaly (since it's a mock class, obviously).

At the moment i would just like to make it work. Any help is appreciated!

Answer 1

Pie is not really a chart with data series but a shape that represents a single portion of an ellipse: https://github.com/xceedsoftware/wpftoolkit/wiki/PieChart .

If you want a pie chart you should take a look at this NuGet package and this answer for an example of how to use it to create a pie chart.

This should give you a pie chart:

xmlns:chartingToolkit="clr-namespace:System.Windows.Controls.DataVisualization.Charting;assembly=System.Windows.Controls.DataVisualization.Toolkit"
...
<Grid Grid.Row="1">
    <chartingToolkit:Chart Margin="0" Title="Chart Title" DataContext="{Binding PieCollection}">
        <chartingToolkit:PieSeries ItemsSource="{Binding}" 
                                   DependentValuePath="Share" 
                                   IndependentValuePath="Name">
        </chartingToolkit:PieSeries>
    </chartingToolkit:Chart>
</Grid>