Use Generic Host to enable DI for BlinForms apps

- Wrap BlinForms startup logic in an IHostedService
- Update BlinForms TodoApp sample to use DI to store the counter state

Blaxamarin.Framework/Blaxamarin.cs

@@ -1,5 +1,6 @@
 using Microsoft.AspNetCore.Components;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
 using Xamarin.Forms;
 
 namespace Blaxamarin.Framework
@@ -11,7 +12,7 @@ namespace Blaxamarin.Framework
             var serviceCollection = new ServiceCollection();
             var serviceProvider = serviceCollection.BuildServiceProvider();
 
-            var renderer = new BlaxamarinRenderer(serviceProvider);
+            var renderer = new BlaxamarinRenderer(serviceProvider, new LoggerFactory());
             var result = renderer.Dispatcher.InvokeAsync(async () =>
             {
                 await renderer.AddComponent<T>();

Blaxamarin.Framework/BlaxamarinRenderer.cs

@@ -1,4 +1,5 @@
 using Emblazon;
+using Microsoft.Extensions.Logging;
 using System;
 using System.Diagnostics;
 using Xamarin.Forms;
@@ -7,8 +8,8 @@ namespace Blaxamarin.Framework
 {
     public class BlaxamarinRenderer : EmblazonRenderer<IFormsControlHandler>
     {
-        public BlaxamarinRenderer(IServiceProvider serviceProvider)
-            : base(serviceProvider)
+        public BlaxamarinRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory)
+            : base(serviceProvider, loggerFactory)
         {
         }
 

BlinForms.Framework/BlinForms.Framework.csproj

@@ -11,6 +11,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="3.0.0-preview9.19423.4" />
   </ItemGroup>
 
   <ItemGroup>

BlinForms.Framework/BlinForms.cs

@@ -1,25 +0,0 @@
-using Microsoft.AspNetCore.Components;
-using Microsoft.Extensions.DependencyInjection;
-using System.Windows.Forms;
-
-namespace BlinForms.Framework
-{
-    public static class BlinForms
-    {
-        public static void Run<T>() where T : IComponent
-        {
-            Application.EnableVisualStyles();
-            Application.SetCompatibleTextRenderingDefault(false);
-
-            var serviceCollection = new ServiceCollection();
-            var serviceProvider = serviceCollection.BuildServiceProvider();
-
-            var renderer = new BlinFormsRenderer(serviceProvider);
-            renderer.Dispatcher.InvokeAsync(() =>
-            {
-                renderer.AddComponent<T>();
-                Application.Run(renderer.RootForm);
-            });
-        }
-    }
-}

BlinForms.Framework/BlinFormsHostBuilderExtensions.cs

@@ -0,0 +1,30 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using System;
+
+namespace BlinForms.Framework
+{
+    public static class BlinFormsHostBuilderExtensions
+    {
+        /// <summary>
+        /// Registers <see cref="BlinFormsHostedService"/> in the DI container. Call this as part of configuring the
+        /// host to enable BlinForms.
+        /// </summary>
+        /// <param name="hostBuilder"></param>
+        /// <returns></returns>
+        public static IHostBuilder AddBlinForms(this IHostBuilder hostBuilder)
+        {
+            if (hostBuilder is null)
+            {
+                throw new ArgumentNullException(nameof(hostBuilder));
+            }
+
+            hostBuilder.ConfigureServices((hostContext, services) =>
+            {
+                services.AddHostedService<BlinFormsHostedService>();
+            });
+
+            return hostBuilder;
+        }
+    }
+}

BlinForms.Framework/BlinFormsHostedService.cs

@@ -0,0 +1,57 @@
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Windows.Forms;
+
+namespace BlinForms.Framework
+{
+    /// <summary>
+    /// An implementation of <see cref="IHostedService"/> that controls the lifetime of a BlinForms application.
+    /// When this service starts, it loads the main form registered by
+    /// <see cref="BlinFormsServiceCollectionExtensions.AddBlinFormsMainForm{TComponent}(Microsoft.Extensions.DependencyInjection.IServiceCollection)"/>.
+    /// The service will request that the application stops when the main form is closed.
+    /// </summary>
+    public class BlinFormsHostedService : IHostedService
+    {
+        private readonly IBlinFormsMainFormType _blinFormsMainForm;
+        private readonly ILoggerFactory _loggerFactory;
+        private readonly IServiceProvider _serviceProvider;
+        private readonly IHostApplicationLifetime _hostApplicationLifetime;
+
+        public BlinFormsHostedService(IBlinFormsMainFormType blinFormsMainForm, ILoggerFactory loggerFactory, IServiceProvider serviceProvider, IHostApplicationLifetime hostApplicationLifetime)
+        {
+            _blinFormsMainForm = blinFormsMainForm;
+            _loggerFactory = loggerFactory;
+            _serviceProvider = serviceProvider;
+            _hostApplicationLifetime = hostApplicationLifetime;
+        }
+
+        public async Task StartAsync(CancellationToken cancellationToken)
+        {
+            Application.EnableVisualStyles();
+            Application.SetCompatibleTextRenderingDefault(false);
+
+            var renderer = new BlinFormsRenderer(_serviceProvider, _loggerFactory);
+            await renderer.Dispatcher.InvokeAsync(() =>
+            {
+                renderer.AddComponent(_blinFormsMainForm.MainFormType);
+                var rootForm = renderer.RootForm;
+                rootForm.FormClosed += OnRootFormFormClosed;
+                Application.Run(rootForm);
+            });
+        }
+
+        private void OnRootFormFormClosed(object sender, FormClosedEventArgs e)
+        {
+            // When the main form closes, request for the application to stop
+            _hostApplicationLifetime.StopApplication();
+        }
+
+        public Task StopAsync(CancellationToken cancellationToken)
+        {
+            return Task.CompletedTask;
+        }
+    }
+}

BlinForms.Framework/BlinFormsMainFormType.cs

@@ -0,0 +1,16 @@
+using Microsoft.AspNetCore.Components;
+using System;
+
+namespace BlinForms.Framework
+{
+    public class BlinFormsMainFormType<TComponent> : IBlinFormsMainFormType
+        where TComponent : IComponent
+    {
+        public BlinFormsMainFormType()
+        {
+            MainFormType = typeof(TComponent);
+        }
+
+        public Type MainFormType { get; }
+    }
+}

BlinForms.Framework/BlinFormsRenderer.cs

@@ -1,4 +1,5 @@
 using Emblazon;
+using Microsoft.Extensions.Logging;
 using System;
 using System.Windows.Forms;
 
@@ -6,8 +7,8 @@ namespace BlinForms.Framework
 {
     public class BlinFormsRenderer : EmblazonRenderer<IWindowsFormsControlHandler>
     {
-        public BlinFormsRenderer(IServiceProvider serviceProvider)
-            : base(serviceProvider)
+        public BlinFormsRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory)
+            : base(serviceProvider, loggerFactory)
         {
         }
 

BlinForms.Framework/BlinFormsServiceCollectionExtensions.cs

@@ -0,0 +1,29 @@
+using Microsoft.AspNetCore.Components;
+using Microsoft.Extensions.DependencyInjection;
+using System;
+
+namespace BlinForms.Framework
+{
+    public static class BlinFormsServiceCollectionExtensions
+    {
+        /// <summary>
+        /// Registers a BlinForms component (typically from a .razor file) as the initial form to load when the
+        /// application start.
+        /// </summary>
+        /// <typeparam name="TComponent"></typeparam>
+        /// <param name="services"></param>
+        /// <returns></returns>
+        public static IServiceCollection AddBlinFormsMainForm<TComponent>(this IServiceCollection services)
+            where TComponent : class, IComponent
+        {
+            if (services is null)
+            {
+                throw new ArgumentNullException(nameof(services));
+            }
+
+            services.AddSingleton<IBlinFormsMainFormType, BlinFormsMainFormType<TComponent>>();
+
+            return services;
+        }
+    }
+}

BlinForms.Framework/IBlinFormsMainFormType.cs

@@ -0,0 +1,9 @@
+using System;
+
+namespace BlinForms.Framework
+{
+    public interface IBlinFormsMainFormType
+    {
+        Type MainFormType { get; }
+    }
+}

BlinFormsSample/AppState.cs

@@ -0,0 +1,32 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace BlinFormsSample
+{
+    public class AppState
+    {
+        public List<TodoItem> items = new List<TodoItem>();
+
+        public int Counter { get; set; }
+
+        public void ResetAppState()
+        {
+            items.AddRange(
+                new[]
+                {
+                    new TodoItem { Text = "sell dog", IsDone = true },
+                    new TodoItem { Text = "buy cat" },
+                    new TodoItem { Text = "buy cat food" },
+                });
+
+            Counter = 0;
+        }
+
+        public bool IsEmptyAppState()
+        {
+            return
+                !items.Any() &&
+                Counter == 0;
+        }
+    }
+}

BlinFormsSample/Counter.razor

@@ -1,13 +1,13 @@
-<Panel Width="200" Height="100" BackColor="SystemColors.Info">
+@inject AppState AppState
+
+<Panel Width="200" Height="100" BackColor="SystemColors.Info">
     <Button Width="40" Text="+1" OnClick="@HandleClick" />
-    <Label Left="50" Width="200" Text="@("You have pressed " + clickCount + " times")" />
+    <Label Left="50" Width="200" Text="@("You have pressed " + AppState.Counter + " times")" />
 </Panel>
 
 @code {
-    int clickCount = 0;
-
     void HandleClick()
     {
-        clickCount++;
+        AppState.Counter++;
     }
 }

BlinFormsSample/Program.cs

@@ -1,13 +1,28 @@
-using System;
+using BlinForms.Framework;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+using System;
+using System.Threading.Tasks;
 
 namespace BlinFormsSample
 {
     static class Program
     {
         [STAThread]
-        static void Main()
+        static async Task Main()
         {
-            BlinForms.Framework.BlinForms.Run<TodoApp>();
+            await Host.CreateDefaultBuilder()
+                .AddBlinForms()
+                .ConfigureServices((hostContext, services) =>
+                {
+                    // Register app-specific services
+                    services.AddSingleton<AppState>();
+
+                    // Configure main form to load at startup
+                    services.AddBlinFormsMainForm<TodoApp>();
+                })
+                .Build()
+                .RunAsync();
         }
     }
 }

Emblazon/EmblazonRenderer.cs

@@ -15,8 +15,8 @@ namespace Emblazon
         private readonly Dictionary<ulong, Action> _eventRegistrations = new Dictionary<ulong, Action>();
 
 
-        public EmblazonRenderer(IServiceProvider serviceProvider)
-            : base(serviceProvider, new LoggerFactory())
+        public EmblazonRenderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory)
+            : base(serviceProvider, loggerFactory)
         {
         }
 
@@ -27,9 +27,14 @@ namespace Emblazon
         public override Dispatcher Dispatcher { get; }
              = Dispatcher.CreateDefault();
 
-        public Task AddComponent<T>() where T : IComponent
+        public async Task AddComponent<TComponent>() where TComponent : IComponent
         {
-            var component = InstantiateComponent(typeof(T));
+            await AddComponent(typeof(TComponent));
+        }
+
+        public async Task AddComponent(Type componentType)
+        {
+            var component = InstantiateComponent(componentType);
             var componentId = AssignRootComponentId(component);
             var rootControl = CreateRootControl();
 
@@ -39,7 +44,7 @@ namespace Emblazon
             };
 
             _componentIdToAdapter[componentId] = rootAdapter;
-            return RenderRootComponentAsync(componentId);
+            await RenderRootComponentAsync(componentId);
         }
 
         protected override Task UpdateDisplayAsync(in RenderBatch renderBatch)