Donut Control

Learn creating a Donut Control using Windows App SDK with this Tutorial

Donut Control shows how to create a Control that displays values in the form of a Donut Chart, which is like a Pie Chart but with a hole in the middle using a toolkit from NuGet using the Windows App SDK.

Step 1

Follow Setup and Start on how to get Setup and Install what you need for Visual Studio 2022 and Windows App SDK.

In Windows 11 choose Start and then find or search for Visual Studio 2022 and then select it.
Visual Studio 2022
Once Visual Studio 2022 has started select Create a new project.
Create a new project
Then choose the Blank App, Packages (WinUI in Desktop) and then select Next.
Blank App, Packages (WinUI in Desktop)
After that in Configure your new project type in the Project name as DonutControl, then select a Location and then select Create to start a new Solution.
Configure project

Step 2

Then in Visual Studio within Solution Explorer for the Solution, right click on the Project shown below the Solution and then select Manage NuGet Packages...

Manage NuGet Packages

Step 3

Then in the NuGet Package Manager from the Browse tab search for Comentsys.Toolkit.WindowsAppSdk and then select Comentsys.Toolkit.WindowsAppSdk by Comentsys as indicated and select Install

NuGet Package Manager Comentsys.Toolkit.WindowsAppSdk

This will add the package for Comentsys.Toolkit.WindowsAppSdk to your Project. If you get the Preview Changes screen saying Visual Studio is about to make changes to this solution. Click OK to proceed with the changes listed below. You can read the message and then select OK to Install the package, then you can close the tab for Nuget: DonutControl by selecting the x next to it.

Step 4

Then in Visual Studio within Solution Explorer for the Solution, right click on the Project shown below the Solution and then select Add then New Item…

Add New Item

Step 5

Then in Add New Item from the C# Items list, select Code and then select Code File from the list next to this, then type in the name of Library.cs and then Click on Add.

Add New Code File

Step 6

You will now be in the View for the Code of Library.cs and then you need to type the following Code:

using Comentsys.Toolkit.WindowsAppSdk;
using Microsoft.UI;
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Controls;
using Microsoft.UI.Xaml.Media;
using System.Collections.Generic;
using System.Linq;
using Windows.UI;

namespace DonutControl;

public class Donut : Grid
    private const double total = 100;
    private const double circle = 360;

    private List<double> _items = new();

    // Donut GetSector & Percentages Method

    // Donut Layout Method

    // Donut Properties


public class Library
    private readonly List<Color> _colours = new()

    // Library Methods 


Library.cs defines a namespace which allows classes to be defined together, usually each is separate but will be defined in Library.cs along with adding using statements such as for the package of Comentsys.Toolkit.WindowsAppSdk.

Step 7

While still in the namespace of DonutControl in Library.cs and in the class of Donut after the Comment of // Donut GetSector & Percentages Method type the following Methods:

private static Sector GetSector(double size, double start,
    double finish, double radius, double hole, Color fill)
    Sector sector = new()
        Hole = hole,
        Start = start,
        Finish = finish,
        Radius = radius,
        Fill = new SolidColorBrush(fill),
        Stroke = new SolidColorBrush(Colors.WhiteSmoke)
    Canvas.SetLeft(sector, (size - radius * 2) / 2);
    Canvas.SetTop(sector, (size - radius * 2) / 2);
    return sector;

private List<double> Percentages()
    List<double> results = new();
    double total = _items.Sum();
    foreach (double item in _items)
        results.Add(item / total * 100);
    return results.OrderBy(o => o).ToList();

GetSector is used to obtain a Sector from Comentsys.Toolkit.WindowsAppSdk and then set the values for this along with positioning it on a Canvas and Percentages is used to get the values as a set of percentages to be displayed in the Control.

Step 8

While still in the namespace of DonutControl in Library.cs and in the class of Donut after the Comment of // Donut Layout Method type the following Method:

internal void Layout()
    double finish = 0;
    double value = circle / total;
    List<double> percentages = Percentages();
    Canvas canvas = new()
        Width = Radius * 2,
        Height = Radius * 2
    for (int index = 0; index < percentages.Count; index++)

        double start = finish;
        double percentage = percentages[index];
        Color colour = (index < Palette.Count) ? Palette[index] : Colors.Black;
        double sweep = value * percentage;
        finish = sweep + start;
        if (finish >= 360)
            finish = sweep;
        Sector sector = GetSector(Radius * 2, start, finish, Radius, Hole, colour);
    Viewbox viewbox = new()
        Child = canvas

Layout uses Percentages to get the values to be used then builds up the Control by using GetSector and will use Properties that will be defined in the next Step.

Step 9

While still in the namespace of DonutControl in Library.cs and in the class of Donut after the Comment of // Donut Properties type the following Properties:

public List<Color> Palette { get; set; } = new();

public List<double> Items
    get { return _items; }
    set { _items = value; Layout(); }

public static readonly DependencyProperty RadiusProperty =
DependencyProperty.Register("Radius", typeof(int),
typeof(Donut), new PropertyMetadata(100, new PropertyChangedCallback(
(DependencyObject obj, DependencyPropertyChangedEventArgs eventArgs) =>

public static readonly DependencyProperty HoleProperty =
DependencyProperty.Register("Hole", typeof(UIElement),
typeof(Donut), new PropertyMetadata(50.0, new PropertyChangedCallback(
(DependencyObject obj, DependencyPropertyChangedEventArgs eventArgs) =>

public int Radius
    get { return (int)GetValue(RadiusProperty); }
    set { SetValue(RadiusProperty, value); Layout(); }

public double Hole
    get { return (double)GetValue(HoleProperty); }
    set { SetValue(HoleProperty, value); Layout(); }

Palette is used for the colours for the Control and Items is for the values. Radius and Hole also have Dependency Properties which are used for Data Binding.

Step 10

Still in Library.cs for the namespace of DonutControl and in the class of Library after the Comment of // Library Methods by typing the following Methods:

private int Fibonacci(int value) => value > 1 ?
    Fibonacci(value - 1) + Fibonacci(value - 2) : value;

public void Load(Grid grid)
    Donut donut = new()
        Palette = _colours
    donut.Items = Enumerable.Range(1, donut.Palette.Count)
    .Select(Fibonacci).Select(s => (double)s).ToList();

Fibonacci is used to get numbers to use with the Control and is used by Load to get the values to be displayed using the Control.

Step 11

Within Solution Explorer for the Solution double-click on MainWindow.xaml to see the XAML for the Main Window.
Solution Explorer MainWindow.xaml

Step 12

In the XAML for MainWindow.xaml there will be some XAML for a StackPanel, this should be Removed:

<StackPanel Orientation="Horizontal" 
HorizontalAlignment="Center" VerticalAlignment="Center">
    <Button x:Name="myButton" Click="myButton_Click">Click Me</Button>

Step 13

While still in the XAML for MainWindow.xaml above </Window>, type in the following XAML:

        <Grid Margin="50" Name="Display" 
        VerticalAlignment="Center" Loaded="Load"/>

This XAML contains a Grid with a Viewbox which will Scale a Grid and a Loaded event handler for Load.

Step 14

Within Solution Explorer for the Solution select the arrow next to MainWindow.xaml then double-click on MainWindow.xaml.cs to see the Code for the Main Window.
Solution Explorer MainWindow.xaml.cs

Step 15

In the Code for MainWindow.xaml.cs there be a Method of myButton_Click(...) this should be Removed by removing the following:

private void myButton_Click(object sender, RoutedEventArgs e)
    myButton.Content = "Clicked";

Step 16

Once myButton_Click(...) has been removed, within the Constructor of public MainWindow() { ... } and below the line of this.InitializeComponent(); type in the following Code:

private readonly Library _library = new();

private void Load(object sender, RoutedEventArgs e) =>

Here an Instance of Library is created then below this is the Method of Load that will be used with Event Handler from the XAML, this Method uses Arrow Syntax with the => for an expression body which is useful when a Method only has one line.

Step 17

That completes the Windows App SDK application. In Visual Studio 2022 from the Toolbar select DonutControl (Package) to Start the application.
DonutControl (Package)

Step 18

Once running you will see the Donut Control displayed showing a representation of the first few numbers of the Fibonacci Sequence.

Donut Control Running and Output

Step 19

To Exit the Windows App SDK application, select the Close button from the top right of the application as that concludes this Tutorial for Windows App SDK from!
Close application