hosting-winui3

Introduction

Default WinUI3 project templates are not suitable for clean usage with Generic Host. This library delivers IHostedService implementation as a wrapper around WinUI3 UI layer.

• Integrates WinUI3 layer with Generic Host through IHostedService implementation
• Enables Dependency Injection into App.cs

How to use?

Generic Host is usually instantiated at the entry point to the application, i.e. Main() function.

Default WinUI3 project templates do not come with Main() function exposed by default, but we can override this easily by making few minor changes.

Step 1: Disable auto-generated Program.cs by defining DISABLE_XAML_GENERATED_MAIN constant in the project file

  <PropertyGroup>
    <DefineConstants>DISABLE_XAML_GENERATED_MAIN</DefineConstants>
  </PropertyGroup>

Step 2: Add a new Program.cs class

public static class Program
{
    static void Main(string[] args) { }
}

Step 3: Instantiate IHost and configure the pipeline. Add WinUI3 hosting by invoking .UseWinUI3<App>() on the IHostBuilder instance.

using EMT.Extensions.Hosting.WinUI3; 

public static class Program
{
    static void Main(string[] args)
    {
        using var host = Host.CreateDefaultBuilder()
                             .UseContentRoot(AppContext.BaseDirectory)
                             .UseWinUI3<App>()
                             .ConfigureServices((context, services) =>
                             {
                                 services.AddSingleton<MainWindow>();
                             })
                             .Build();
        host.Run();
    }
}

App class implementation details

Invoking UseWinUI3<App>() function registers IHostedService implementation and App class with the DI container. When the hosting starts the App will be instantiated and launched.

Below is a sample of App class taking IServiceProvider as a dependency then using it to pull MainWindow instance.

    public partial class App : Application
    {
        private Window mainWindow;
        private readonly IServiceProvider provider;
        public App(IServiceProvider provider)
        {
            this.provider = provider ?? throw new ArgumentNullException(nameof(provider));

            this.InitializeComponent();
        }

        protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
        {
            mainWindow = provider.GetRequiredService<MainWindow>();
            mainWindow.Activate();
        }
    }

Samples

Sample app can be found under Samples directory.