feat: Added option to run an action before showing the main form (#35)

* feat: Added option to run an action before showing the main form

* fix: Direct call for `GetRequiredService<T>`

* fix: Fixed flacky tests

src/NetEvolve.Extensions.Hosting.WinForms/Internals/FormularProvider.cs

@@ -42,7 +42,7 @@ public T GetFormular<T>()
         _semaphore.Wait();
         try
         {
-            return synchronizationContext.Invoke(() => serviceProvider.GetRequiredService<T>())!;
+            return serviceProvider.GetRequiredService<T>();
         }
         finally
         {

src/NetEvolve.Extensions.Hosting.WinForms/Internals/WindowsFormsHostedService.cs

@@ -84,11 +84,17 @@ private void OnApplicationStopping()
     private void StartUIThread()
     {
         _ = Application.SetHighDpiMode(_options.HighDpiMode);
+        Application.SetCompatibleTextRenderingDefault(_options.CompatibleTextRenderingDefault);
         if (_options.EnableVisualStyles)
         {
             Application.EnableVisualStyles();
         }
-        Application.SetCompatibleTextRenderingDefault(_options.CompatibleTextRenderingDefault);
+
+        if (_options.DefaultFont is not null)
+        {
+            Application.SetDefaultFont(_options.DefaultFont);
+        }
+
         Application.ApplicationExit += OnApplicationExit;
 
         // Disable the auto install of the WindowsFormsSynchronizationContext.
@@ -98,6 +104,15 @@ private void StartUIThread()
         synchronizationContextProvider.Context = new WindowsFormsSynchronizationContext();
         SynchronizationContext.SetSynchronizationContext(synchronizationContextProvider.Context);
 
+        if (_options.PreloadAction is not null)
+        {
+            using (var scope = serviceProvider.CreateScope())
+            {
+                var formsProvider = scope.ServiceProvider.GetRequiredService<IFormularProvider>();
+                _options.PreloadAction.Invoke(scope.ServiceProvider, formsProvider);
+            }
+        }
+
         var applicationContext = serviceProvider.GetRequiredService<ApplicationContext>();
 
         Application.Run(applicationContext);

src/NetEvolve.Extensions.Hosting.WinForms/WindowsFormsOptions.cs

@@ -1,5 +1,7 @@
 namespace NetEvolve.Extensions.Hosting.WinForms;
 
+using System;
+using System.Drawing;
 using System.Windows.Forms;
 
 /// <summary>
@@ -36,4 +38,14 @@ public sealed class WindowsFormsOptions
     /// The default is <see langword="false"/>.
     /// </summary>
     public bool EnableConsoleShutdown { get; set; }
+
+    /// <summary>
+    /// The default font to use inside the WinForms host. If <see langword="null"/> the system default font is used.
+    /// </summary>
+    public Font? DefaultFont { get; set; }
+
+    /// <summary>
+    /// Optional action to run before the main form is created. Something like a splash screen, login form, etc.
+    /// </summary>
+    public Action<IServiceProvider, IFormularProvider>? PreloadAction { get; set; }
 }

tests/NetEvolve.Extensions.Hosting.WinForms.Tests.Unit/Internals/WindowsFormsSynchronizationContextProviderTests.cs

@@ -182,7 +182,7 @@ public async Task InvokeAsync_Action_CancellationTokenCanceled_ThrowsTaskCancele
         WindowsFormsSynchronizationContext.AutoInstall = false;
         var provider = new WindowsFormsSynchronizationContextProvider
         {
-            Context = SynchronizationContext.Current!
+            Context = new WindowsFormsSynchronizationContext()
         };
 
         // Act
@@ -264,7 +264,7 @@ public async Task InvokeAsync_Func_CancellationTokenCanceled_ThrowsTaskCanceledE
         WindowsFormsSynchronizationContext.AutoInstall = false;
         var provider = new WindowsFormsSynchronizationContextProvider
         {
-            Context = SynchronizationContext.Current!
+            Context = new WindowsFormsSynchronizationContext()
         };
 
         // Act
@@ -349,7 +349,7 @@ public async Task InvokeAsync_FuncWithInput_CancellationTokenCanceled_ThrowsTask
         WindowsFormsSynchronizationContext.AutoInstall = false;
         var provider = new WindowsFormsSynchronizationContextProvider
         {
-            Context = SynchronizationContext.Current!
+            Context = new WindowsFormsSynchronizationContext()
         };
 
         // Act