Add Winforms Sample

Author: nikeee

README.md

@@ -4,26 +4,26 @@ For single instance applications on .NET Core
 NuGet Package: https://www.nuget.org/packages/SingleInstanceCore/
 # Usage
 
-Note: Usage examples are for WPF desktop applications. For other platforms/frameworks, inheritance and initialization should be done accordingly, not exactly like the examples.
+Note: Usage examples are for WPF and Winforms desktop applications. For other platforms/frameworks, inheritance and initialization should be done accordingly, not exactly like the examples.
 
 The class that handles instance invokation should inherit ISingleInstance and implement OnInstanceInvoked method.
 
-E.g. in App class (App.xaml.cs):
+## WPF
+E.g. in App class (`App.xaml.cs`):
 ```csharp
 public partial class App : Application, ISingleInstance
 {
 	public void OnInstanceInvoked(string[] args)
 	{
-			//What to do with the args another instance has sent
+		// What to do with the args another instance has sent
 	}
-	...
+	// ...
 }
 ```
 Initialization of instance should be done when application is starting, and cleanup method should be called on the exit point of the application. 
 
-E.g. in App class (App.xaml.cs):
+E.g. in App class (`App.xaml.cs`):
 ```csharp
-
 	private void Application_Startup(object sender, StartupEventArgs e)
 	{
 		bool isFirstInstance = this.InitializeAsFirstInstance("soheilkd_ExampleIPC");
@@ -42,3 +42,46 @@ E.g. in App class (App.xaml.cs):
 		SingleInstance.Cleanup();
 	}
 ```
+
+## Winforms
+Winforms doesn't have an Application.cs that could implement the `ISingleInstance` interface. We have to define one ourselves.
+```csharp
+static class Program
+{
+	[STAThread]
+	static void Main(string[] args)
+	{
+		var app = new YourApplication();
+
+		var isFirstInstance = app.InitializeAsFirstInstance(nameof(YourApplication));
+		if (isFirstInstance)
+		{
+			try
+			{
+				app.Run();
+			}
+			finally
+			{
+				SingleInstance.Cleanup();
+			}
+		}
+	}
+}
+
+class YourApplication : ISingleInstance
+{
+	public void Run()
+	{
+		Application.SetHighDpiMode(HighDpiMode.SystemAware);
+		Application.EnableVisualStyles();
+		Application.SetCompatibleTextRenderingDefault(false);
+		Application.Run(new MainForm()); // Blocks until the main window is closed
+	}
+
+	public void OnInstanceInvoked(string[] args)
+	{
+		// What to do with the args another instance has sent
+	}
+}
+
+```