Associate with files and URIs on windows

osu.Desktop/OsuGameDesktop.cs

@@ -86,8 +86,8 @@ public OsuGameDesktop(string[]? args = null)
         [SupportedOSPlatform("windows")]
         private string? getStableInstallPathFromRegistry()
         {
-            using (RegistryKey? key = Registry.ClassesRoot.OpenSubKey("osu"))
-                return key?.OpenSubKey(@"shell\open\command")?.GetValue(string.Empty)?.ToString()?.Split('"')[1].Replace("osu!.exe", "");
+            using (RegistryKey? key = Registry.ClassesRoot.OpenSubKey("osu!"))
+                return key?.OpenSubKey(WindowsAssociationManager.SHELL_OPEN_COMMAND)?.GetValue(string.Empty)?.ToString()?.Split('"')[1].Replace("osu!.exe", "");
         }
 
         protected override UpdateManager CreateUpdateManager()

osu.Desktop/Program.cs

@@ -5,6 +5,7 @@
 using System.IO;
 using System.Runtime.Versioning;
 using osu.Desktop.LegacyIpc;
+using osu.Desktop.Windows;
 using osu.Framework;
 using osu.Framework.Development;
 using osu.Framework.Logging;
@@ -173,13 +174,16 @@ private static void setupSquirrel()
             {
                 tools.CreateShortcutForThisExe();
                 tools.CreateUninstallerRegistryEntry();
+                WindowsAssociationManager.InstallAssociations();
             }, onAppUpdate: (_, tools) =>
             {
                 tools.CreateUninstallerRegistryEntry();
+                WindowsAssociationManager.UpdateAssociations();
             }, onAppUninstall: (_, tools) =>
             {
                 tools.RemoveShortcutForThisExe();
                 tools.RemoveUninstallerRegistryEntry();
+                WindowsAssociationManager.UninstallAssociations();
             }, onEveryRun: (_, _, _) =>
             {
                 // While setting the `ProcessAppUserModelId` fixes duplicate icons/shortcuts on the taskbar, it currently

osu.Desktop/Windows/Icons.cs

@@ -0,0 +1,17 @@
+// Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.IO;
+
+namespace osu.Desktop.Windows
+{
+    public static class Icons
+    {
+        /// <summary>
+        /// Fully qualified path to the directory that contains icons (in the installation folder).
+        /// </summary>
+        private static readonly string icon_directory = Path.GetDirectoryName(typeof(Icons).Assembly.Location)!;
+
+        public static string Lazer => Path.Join(icon_directory, "lazer.ico");
+    }
+}

osu.Desktop/Windows/WindowsAssociationManager.cs

@@ -0,0 +1,288 @@
+// Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
+using Microsoft.Win32;
+using osu.Framework.Localisation;
+using osu.Framework.Logging;
+using osu.Game.Localisation;
+
+namespace osu.Desktop.Windows
+{
+    [SupportedOSPlatform("windows")]
+    public static class WindowsAssociationManager
+    {
+        private const string software_classes = @"Software\Classes";
+
+        /// <summary>
+        /// Sub key for setting the icon.
+        /// https://learn.microsoft.com/en-us/windows/win32/com/defaulticon
+        /// </summary>
+        private const string default_icon = @"DefaultIcon";
+
+        /// <summary>
+        /// Sub key for setting the command line that the shell invokes.
+        /// https://learn.microsoft.com/en-us/windows/win32/com/shell
+        /// </summary>
+        internal const string SHELL_OPEN_COMMAND = @"Shell\Open\Command";
+
+        private static readonly string exe_path = Path.ChangeExtension(typeof(WindowsAssociationManager).Assembly.Location, ".exe").Replace('/', '\\');
+
+        /// <summary>
+        /// Program ID prefix used for file associations. Should be relatively short since the full program ID has a 39 character limit,
+        /// see https://learn.microsoft.com/en-us/windows/win32/com/-progid--key.
+        /// </summary>
+        private const string program_id_prefix = "osu.File";
+
+        private static readonly FileAssociation[] file_associations =
+        {
+            new FileAssociation(@".osz", WindowsAssociationManagerStrings.OsuBeatmap, Icons.Lazer),
+            new FileAssociation(@".olz", WindowsAssociationManagerStrings.OsuBeatmap, Icons.Lazer),
+            new FileAssociation(@".osr", WindowsAssociationManagerStrings.OsuReplay, Icons.Lazer),
+            new FileAssociation(@".osk", WindowsAssociationManagerStrings.OsuSkin, Icons.Lazer),
+        };
+
+        private static readonly UriAssociation[] uri_associations =
+        {
+            new UriAssociation(@"osu", WindowsAssociationManagerStrings.OsuProtocol, Icons.Lazer),
+            new UriAssociation(@"osump", WindowsAssociationManagerStrings.OsuMultiplayer, Icons.Lazer),
+        };
+
+        /// <summary>
+        /// Installs file and URI associations.
+        /// </summary>
+        /// <remarks>
+        /// Call <see cref="UpdateDescriptions"/> in a timely fashion to keep descriptions up-to-date and localised.
+        /// </remarks>
+        public static void InstallAssociations()
+        {
+            try
+            {
+                updateAssociations();
+                updateDescriptions(null); // write default descriptions in case `UpdateDescriptions()` is not called.
+                NotifyShellUpdate();
+            }
+            catch (Exception e)
+            {
+                Logger.Error(e, @$"Failed to install file and URI associations: {e.Message}");
+            }
+        }
+
+        /// <summary>
+        /// Updates associations with latest definitions.
+        /// </summary>
+        /// <remarks>
+        /// Call <see cref="UpdateDescriptions"/> in a timely fashion to keep descriptions up-to-date and localised.
+        /// </remarks>
+        public static void UpdateAssociations()
+        {
+            try
+            {
+                updateAssociations();
+                NotifyShellUpdate();
+            }
+            catch (Exception e)
+            {
+                Logger.Error(e, @"Failed to update file and URI associations.");
+            }
+        }
+
+        public static void UpdateDescriptions(LocalisationManager localisationManager)
+        {
+            try
+            {
+                updateDescriptions(localisationManager);
+                NotifyShellUpdate();
+            }
+            catch (Exception e)
+            {
+                Logger.Error(e, @"Failed to update file and URI association descriptions.");
+            }
+        }
+
+        public static void UninstallAssociations()
+        {
+            try
+            {
+                foreach (var association in file_associations)
+                    association.Uninstall();
+
+                foreach (var association in uri_associations)
+                    association.Uninstall();
+
+                NotifyShellUpdate();
+            }
+            catch (Exception e)
+            {
+                Logger.Error(e, @"Failed to uninstall file and URI associations.");
+            }
+        }
+
+        public static void NotifyShellUpdate() => SHChangeNotify(EventId.SHCNE_ASSOCCHANGED, Flags.SHCNF_IDLIST, IntPtr.Zero, IntPtr.Zero);
+
+        /// <summary>
+        /// Installs or updates associations.
+        /// </summary>
+        private static void updateAssociations()
+        {
+            foreach (var association in file_associations)
+                association.Install();
+
+            foreach (var association in uri_associations)
+                association.Install();
+        }
+
+        private static void updateDescriptions(LocalisationManager? localisation)
+        {
+            foreach (var association in file_associations)
+                association.UpdateDescription(getLocalisedString(association.Description));
+
+            foreach (var association in uri_associations)
+                association.UpdateDescription(getLocalisedString(association.Description));
+
+            string getLocalisedString(LocalisableString s)
+            {
+                if (localisation == null)
+                    return s.ToString();
+
+                var b = localisation.GetLocalisedBindableString(s);
+                b.UnbindAll();
+                return b.Value;
+            }
+        }
+
+        #region Native interop
+
+        [DllImport("Shell32.dll")]
+        private static extern void SHChangeNotify(EventId wEventId, Flags uFlags, IntPtr dwItem1, IntPtr dwItem2);
+
+        private enum EventId
+        {
+            /// <summary>
+            /// A file type association has changed. <see cref="Flags.SHCNF_IDLIST"/> must be specified in the uFlags parameter.
+            /// dwItem1 and dwItem2 are not used and must be <see cref="IntPtr.Zero"/>. This event should also be sent for registered protocols.
+            /// </summary>
+            SHCNE_ASSOCCHANGED = 0x08000000
+        }
+
+        private enum Flags : uint
+        {
+            SHCNF_IDLIST = 0x0000
+        }
+
+        #endregion
+
+        private record FileAssociation(string Extension, LocalisableString Description, string IconPath)
+        {
+            private string programId => $@"{program_id_prefix}{Extension}";
+
+            /// <summary>
+            /// Installs a file extenstion association in accordance with https://learn.microsoft.com/en-us/windows/win32/com/-progid--key
+            /// </summary>
+            public void Install()
+            {
+                using var classes = Registry.CurrentUser.OpenSubKey(software_classes, true);
+                if (classes == null) return;
+
+                // register a program id for the given extension
+                using (var programKey = classes.CreateSubKey(programId))
+                {
+                    using (var defaultIconKey = programKey.CreateSubKey(default_icon))
+                        defaultIconKey.SetValue(null, IconPath);
+
+                    using (var openCommandKey = programKey.CreateSubKey(SHELL_OPEN_COMMAND))
+                        openCommandKey.SetValue(null, $@"""{exe_path}"" ""%1""");
+                }
+
+                using (var extensionKey = classes.CreateSubKey(Extension))
+                {
+                    // set ourselves as the default program
+                    extensionKey.SetValue(null, programId);
+
+                    // add to the open with dialog
+                    // https://learn.microsoft.com/en-us/windows/win32/shell/how-to-include-an-application-on-the-open-with-dialog-box
+                    using (var openWithKey = extensionKey.CreateSubKey(@"OpenWithProgIds"))
+                        openWithKey.SetValue(programId, string.Empty);
+                }
+            }
+
+            public void UpdateDescription(string description)
+            {
+                using var classes = Registry.CurrentUser.OpenSubKey(software_classes, true);
+                if (classes == null) return;
+
+                using (var programKey = classes.OpenSubKey(programId, true))
+                    programKey?.SetValue(null, description);
+            }
+
+            /// <summary>
+            /// Uninstalls the file extenstion association in accordance with https://learn.microsoft.com/en-us/windows/win32/shell/fa-file-types#deleting-registry-information-during-uninstallation
+            /// </summary>
+            public void Uninstall()
+            {
+                using var classes = Registry.CurrentUser.OpenSubKey(software_classes, true);
+                if (classes == null) return;
+
+                using (var extensionKey = classes.OpenSubKey(Extension, true))
+                {
+                    // clear our default association so that Explorer doesn't show the raw programId to users
+                    // the null/(Default) entry is used for both ProdID association and as a fallback friendly name, for legacy reasons
+                    if (extensionKey?.GetValue(null) is string s && s == programId)
+                        extensionKey.SetValue(null, string.Empty);
+
+                    using (var openWithKey = extensionKey?.CreateSubKey(@"OpenWithProgIds"))
+                        openWithKey?.DeleteValue(programId, throwOnMissingValue: false);
+                }
+
+                classes.DeleteSubKeyTree(programId, throwOnMissingSubKey: false);
+            }
+        }
+
+        private record UriAssociation(string Protocol, LocalisableString Description, string IconPath)
+        {
+            /// <summary>
+            /// "The <c>URL Protocol</c> string value indicates that this key declares a custom pluggable protocol handler."
+            /// See https://learn.microsoft.com/en-us/previous-versions/windows/internet-explorer/ie-developer/platform-apis/aa767914(v=vs.85).
+            /// </summary>
+            public const string URL_PROTOCOL = @"URL Protocol";
+
+            /// <summary>
+            /// Registers an URI protocol handler in accordance with https://learn.microsoft.com/en-us/previous-versions/windows/internet-explorer/ie-developer/platform-apis/aa767914(v=vs.85).
+            /// </summary>
+            public void Install()
+            {
+                using var classes = Registry.CurrentUser.OpenSubKey(software_classes, true);
+                if (classes == null) return;
+
+                using (var protocolKey = classes.CreateSubKey(Protocol))
+                {
+                    protocolKey.SetValue(URL_PROTOCOL, string.Empty);
+
+                    using (var defaultIconKey = protocolKey.CreateSubKey(default_icon))
+                        defaultIconKey.SetValue(null, IconPath);
+
+                    using (var openCommandKey = protocolKey.CreateSubKey(SHELL_OPEN_COMMAND))
+                        openCommandKey.SetValue(null, $@"""{exe_path}"" ""%1""");
+                }
+            }
+
+            public void UpdateDescription(string description)
+            {
+                using var classes = Registry.CurrentUser.OpenSubKey(software_classes, true);
+                if (classes == null) return;
+
+                using (var protocolKey = classes.OpenSubKey(Protocol, true))
+                    protocolKey?.SetValue(null, $@"URL:{description}");
+            }
+
+            public void Uninstall()
+            {
+                using var classes = Registry.CurrentUser.OpenSubKey(software_classes, true);
+                classes?.DeleteSubKeyTree(Protocol, throwOnMissingSubKey: false);
+            }
+        }
+    }
+}

osu.Desktop/osu.Desktop.csproj

@@ -31,4 +31,7 @@
   <ItemGroup Label="Resources">
     <EmbeddedResource Include="lazer.ico" />
   </ItemGroup>
+  <ItemGroup Label="Windows Icons">
+    <Content Include="*.ico" CopyToOutputDirectory="PreserveNewest" CopyToPublishDirectory="PreserveNewest" />
+  </ItemGroup>
 </Project>

osu.Desktop/osu.nuspec

@@ -20,6 +20,7 @@
       <file src="**.dll" target="lib\net45\"/>
       <file src="**.config" target="lib\net45\"/>
       <file src="**.json" target="lib\net45\"/>
+      <file src="**.ico" target="lib\net45\"/>
       <file src="icon.png" target=""/>
     </files>
 </package>

osu.Game/Localisation/WindowsAssociationManagerStrings.cs

@@ -0,0 +1,39 @@
+// Copyright (c) ppy Pty Ltd <[email protected]>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Localisation;
+
+namespace osu.Game.Localisation
+{
+    public static class WindowsAssociationManagerStrings
+    {
+        private const string prefix = @"osu.Game.Resources.Localisation.WindowsAssociationManager";
+
+        /// <summary>
+        /// "osu! Beatmap"
+        /// </summary>
+        public static LocalisableString OsuBeatmap => new TranslatableString(getKey(@"osu_beatmap"), @"osu! Beatmap");
+
+        /// <summary>
+        /// "osu! Replay"
+        /// </summary>
+        public static LocalisableString OsuReplay => new TranslatableString(getKey(@"osu_replay"), @"osu! Replay");
+
+        /// <summary>
+        /// "osu! Skin"
+        /// </summary>
+        public static LocalisableString OsuSkin => new TranslatableString(getKey(@"osu_skin"), @"osu! Skin");
+
+        /// <summary>
+        /// "osu!"
+        /// </summary>
+        public static LocalisableString OsuProtocol => new TranslatableString(getKey(@"osu_protocol"), @"osu!");
+
+        /// <summary>
+        /// "osu! Multiplayer"
+        /// </summary>
+        public static LocalisableString OsuMultiplayer => new TranslatableString(getKey(@"osu_multiplayer"), @"osu! Multiplayer");
+
+        private static string getKey(string key) => $@"{prefix}:{key}";
+    }
+}