Merge pull request #11 from victor-david/feature-one-instance

Merge feature-one-instance to main

src/Panama/App.xaml.cs

@@ -4,15 +4,15 @@
  * Panama is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License v3.0
  * Panama is distributed in the hope that it will be useful, but without warranty of any kind.
 */
-using Restless.Panama.ViewModel;
 using Restless.Panama.Core;
 using Restless.Panama.Database.Core;
-using Restless.Panama.Resources;
+using Restless.Panama.Database.Tables;
 using Restless.Panama.Utility;
+using Restless.Panama.ViewModel;
+using Restless.Toolkit.Controls;
 using System;
+using System.Threading;
 using System.Windows;
-using Restless.Panama.Database.Tables;
-using Restless.Toolkit.Controls;
 
 namespace Restless.Panama
 {
@@ -21,6 +21,11 @@ namespace Restless.Panama
     /// </summary>
     public partial class App : Application
     {
+        #region Private
+        private const string ApplicationId = "Panama.d9c20b23-f278-4349-a292-17e5a6abb15a";
+        private static readonly Mutex AppMutex = new(true, ApplicationId);
+        #endregion
+
         #region Protected methods
         /// <summary>
         /// Called when the application is starting.
@@ -32,6 +37,14 @@ public partial class App : Application
         protected override void OnStartup(StartupEventArgs e)
         {
             base.OnStartup(e);
+
+            /* Prevent app from being run more than once */
+            if (!AppMutex.WaitOne(TimeSpan.Zero, true))
+            {
+                NativeMethods.PostMessage((IntPtr)NativeMethods.HWND_BROADCAST, NativeMethods.WM_SHOW_ACTIVE_WIN, IntPtr.Zero, IntPtr.Zero);
+                Environment.Exit(0);
+            }
+
             try
             {
                 RunApplication(e);
@@ -53,6 +66,7 @@ protected override void OnExit(ExitEventArgs e)
             base.OnExit(e);
             Config.Instance.SaveFilterObjects();
             DatabaseController.Instance.Shutdown(saveTables: true);
+            AppMutex.ReleaseMutex();
         }
         #endregion
 

src/Panama/Core/Other/NativeMethods.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Restless.Panama.Core
+{
+    /// <summary>
+    /// Provides native methods.
+    /// </summary>
+    internal static class NativeMethods
+    {
+        public const int HWND_BROADCAST = 0xffff;
+        public static readonly int WM_SHOW_ACTIVE_WIN = RegisterWindowMessage("911BEAEF-5448-4CB8-A0CF-4A839B7602D1");
+
+        [DllImport("user32")]
+        public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
+
+        [DllImport("user32", CharSet = CharSet.Unicode)]
+        public static extern int RegisterWindowMessage(string message);
+    }
+}

src/Panama/Panama.csproj

@@ -13,7 +13,7 @@
     <PackageProjectUrl>https://github.com/victor-david/panama</PackageProjectUrl>
     <RepositoryUrl>https://github.com/victor-david/panama</RepositoryUrl>    
     <PackageLicenseExpression>GPL-3.0-only</PackageLicenseExpression>
-    <Version>4.0.33</Version>
+    <Version>4.0.34</Version>
     <ApplicationIcon>App.Main.ico</ApplicationIcon>
   </PropertyGroup>
 

src/Panama/View/MainWindow.xaml.cs

@@ -4,15 +4,79 @@
  * Panama is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License v3.0
  * Panama is distributed in the hope that it will be useful, but without warranty of any kind.
 */
+using Restless.Panama.Core;
 using Restless.Toolkit.Controls;
+using System;
+using System.Windows;
+using System.Windows.Interop;
 
 namespace Restless.Panama.View
 {
     public partial class MainWindow : AppWindow
     {
+        #region Private
+        private static MainWindow staticMain;
+        #endregion
+
+        /************************************************************************/
+
+        #region Constructor
+        /// <summary>
+        /// Initializes a new instance of the <see cref="MainWindow"/> class.
+        /// </summary>
         public MainWindow()
         {
             InitializeComponent();
         }
+        #endregion
+
+        /************************************************************************/
+
+        #region Protected methods
+        /// <inheritdoc/>
+        protected override void OnSourceInitialized(EventArgs e)
+        {
+            base.OnSourceInitialized(e);
+            if (PresentationSource.FromVisual(this) is HwndSource hwndSource)
+            {
+                staticMain = this;
+                hwndSource.AddHook(HandleWindowMessage);
+            }
+        }
+        #endregion
+
+        /************************************************************************/
+
+        #region Private methods
+        /// <summary>
+        /// Matches the HwndSourceHook delegate signature so it can be passed to AddHook() as a callback.
+        /// </summary>
+        /// <param name="hwnd">The window handle</param>
+        /// <param name="msg">The message ID</param>
+        /// <param name="wParam">The message's wParam value, historically used in the win32 api for handles and integers</param>
+        /// <param name="lParam">The message's lParam value, historically used in the win32 api to pass pointers</param>
+        /// <param name="handled">A value that indicates whether the message was handled</param>
+        /// <returns></returns>
+        private static IntPtr HandleWindowMessage(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
+        {
+            if (msg == NativeMethods.WM_SHOW_ACTIVE_WIN)
+            {
+                staticMain?.ShowMe();
+                handled = true;
+            }
+            return IntPtr.Zero;
+        }
+
+        private void ShowMe()
+        {
+            if (WindowState == WindowState.Minimized)
+            {
+                WindowState = WindowState.Normal;
+            }
+            bool top = Topmost;
+            Topmost = true;
+            Topmost = top;
+        }
+        #endregion
     }
 }