Add one instance support.

WinAlfred/App.xaml.cs

@@ -1,28 +1,68 @@
 using System;
+using System.Collections.ObjectModel;
+using System.Linq;
 using System.Threading;
 using System.Windows;
+using Microsoft.VisualBasic.ApplicationServices;
+using StartupEventArgs = System.Windows.StartupEventArgs;
 
 namespace WinAlfred
 {
-    /// <summary>
-    /// App.xaml 的交互逻辑
-    /// </summary>
+    public static class EntryPoint
+    {
+        [STAThread]
+        public static void Main(string[] args)
+        {
+            SingleInstanceManager manager = new SingleInstanceManager();
+            manager.Run(args);
+        }
+    }
+
+    // Using VB bits to detect single instances and process accordingly:
+    //  * OnStartup is fired when the first instance loads
+    //  * OnStartupNextInstance is fired when the application is re-run again
+    //    NOTE: it is redirected to this instance thanks to IsSingleInstance
+    public class SingleInstanceManager : WindowsFormsApplicationBase
+    {
+        App app;
+
+        public SingleInstanceManager()
+        {
+            this.IsSingleInstance = true;
+        }
+
+        protected override bool OnStartup(Microsoft.VisualBasic.ApplicationServices.StartupEventArgs e)
+        {
+            // First time app is launched
+            app = new App();
+            app.InitializeComponent();
+            app.Run();
+            return true;
+        }
+
+        protected override void OnStartupNextInstance(StartupNextInstanceEventArgs eventArgs)
+        {
+            // Subsequent launches
+            base.OnStartupNextInstance(eventArgs);
+            app.Activate(eventArgs.CommandLine.ToArray());
+        }
+    }
+
     public partial class App : Application
     {
+        private MainWindow window;
+
         protected override void OnStartup(StartupEventArgs e)
         {
             base.OnStartup(e);
-            bool startupFlag;
-            Mutex mutex = new Mutex(true, "WinAlfred", out startupFlag);
-            if (!startupFlag)
-            {
-                Environment.Exit(0);
-            }
-            else
-            {
-                MainWindow mainWindow = new MainWindow();
-                mainWindow.Show();
-            }
+
+            window = new MainWindow();
+            window.ShowApp(e.Args);
+        }
+
+        public void Activate(string[] commandLine)
+        {
+            window.ShowApp(commandLine);
         }
     }
 }