Creating a Pie Chart

MainPage.xaml.cs

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();

        CreatePieChart();
    }

    private void CreatePieChart()
    {
        // Data for the series.
        var dataPoints = new List<ChartDataPoint>
        {
            new ChartDataPoint { Title = "Work", Value = 9 },
            new ChartDataPoint { Title = "Commute", Value = 1.5 },
            new ChartDataPoint { Title = "Leisure", Value = 6 },
            new ChartDataPoint { Title = "Sleep", Value = 7.5 },
        };

        // Colors for the series.
        var colors = new List<Color>
        {
            Color.FromHex("#BAB65A"),
            Color.FromHex("#6196D1"),
            Color.FromHex("#3D4268"),
            Color.FromHex("#8A56E2"),
        };

        // Root container to hold the chart and any legend
        var container = new Grid();
        container.RowDefinitions.Add(new RowDefinition { Height = new GridLength(3, GridUnitType.Star) });
        container.RowDefinitions.Add(new RowDefinition { Height = new GridLength(1, GridUnitType.Star) });

        // ***** Part 1 - PIE SERIES GENERATION ***** //

        // Sum up all the values to be displayed
        var totalValue = dataPoints.Sum(d => d.Value);

        // Variable to keep track of where each slice ended.
        double currentPosition = 0;

        // Iterate over the data points to create slices.
        for (int i = 0; i < dataPoints.Count; i++)
        {
            // Determine the what percentage that data item's value is of the whole
            double slicePercentage = dataPoints[i].Value / totalValue;

            // Calculate the sweep angle using that percentage amount.
            double sweep = slicePercentage * 360;

            // Create the ArcSegment using the current position and sweep
            var segment = new RadArcSegment
            {
                Center = new Point(0.5, 0.5),
                Size = new Size(1, 1),
                StartAngle = currentPosition,
                SweepAngle = sweep,
            };

            // Important - Calculate the last segment's ending angle in order to have a valid start angle for the next loop.
            currentPosition = currentPosition + sweep - 360;

            // Prepare the required PathFigure and add the ArcSegment
            var figure = new RadPathFigure { StartPoint = new Point(0.5, 0.5) };
            figure.Segments.Add(segment);

            // Create the PathGeometry and add the PathFigure
            var geometry = new RadPathGeometry();
            geometry.Figures.Add(figure);

            // Construct the RadPath
            // - Select a Fill color from the brushes parameter (important: use a modulus to wrap to the beginning)
            // - Use the Geometry created from the value
            var slice = new RadPath
            {
                Fill = new RadSolidColorBrush(colors[i % colors.Count]),
                Geometry = geometry,
                HorizontalOptions = LayoutOptions.Center,
                VerticalOptions = LayoutOptions.Center,
                WidthRequest = 100,
                HeightRequest = 100,
                Margin = new Thickness(0, 20, 0, 0)
            };

            // This isn't necessary, but added for completion.
            Grid.SetRow(slice, 0);

            // Finally, add it to the container.
            container.Children.Add(slice);
        }

        // ***** Part 2 - LEGEND GENERATION ***** //

        // Create a horizontal StackLayout to hold the legend items
        var legendPanel = new StackLayout
        {
            Orientation = StackOrientation.Horizontal,
            HorizontalOptions = LayoutOptions.Center,
            VerticalOptions = LayoutOptions.Center,
            Margin = new Thickness(0, 16, 0, 0),
            Spacing = 5
        };

        // Iterate over the data points and create a legend item with a matching color
        for (int i = 0; i < dataPoints.Count; i++)
        {
            // Use a RadBorder with only a bottom thickness and match the color to the slice
            var legendItem = new RadBorder
            {
                BorderColor = colors[i % colors.Count],
                BorderThickness = new Thickness(0, 0, 0, 2)
            };

            // Create a Label for each data point and use the Title property
            var label = new Label
            {
                Text = dataPoints[i].Title,
                FontSize = 12,
                Margin = new Thickness(0, 0, 0, 2),
                TextColor = Color.DimGray
            };

            legendItem.Content = label;

            legendPanel.Children.Add(legendItem);
        }

        // Insert the legend panel in the root container's 2nd row.
        Grid.SetRow(legendPanel, 1);
        container.Children.Add(legendPanel);


        // ***** Part 3 - Add the container to the UI ***** // 

        this.Content = container;
    }
}

public class ChartDataPoint
{
    public string Title { get; set; }
    public double Value { get; set; }
}