Fix crash when shutting down or restarting #1782

Author: emako

QuickLook/App.xaml

@@ -4,9 +4,7 @@
              xmlns:local="clr-namespace:QuickLook"
              xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"
              xmlns:vio="http://schemas.lepo.co/wpfui/2022/xaml/violeta"
-             Exit="App_OnExit"
-             ShutdownMode="OnExplicitShutdown"
-             Startup="Application_Startup">
+             ShutdownMode="OnExplicitShutdown">
     <Application.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>

QuickLook/App.xaml.cs

@@ -114,6 +114,21 @@ static IEnumerable<string> FetchFiles(string rootPath, string targetFileName)
 
     protected override void OnStartup(StartupEventArgs e)
     {
+        if (!EnsureOSVersion()
+         || !EnsureFirstInstance(e.Args)
+         || !EnsureFolderWritable(SettingHelper.LocalDataPath))
+        {
+            _cleanExit = false;
+            Shutdown();
+            return;
+        }
+
+        RunListener(e);
+
+        // First instance: run and preview this file
+        if (e.Args.Any() && (Directory.Exists(e.Args.First()) || File.Exists(e.Args.First())))
+            PipeServerManager.SendMessage(PipeMessages.Toggle, e.Args.First());
+
         // Exception handling events which are not caught in the Task thread
         TaskScheduler.UnobservedTaskException += (_, e) =>
         {
@@ -202,31 +217,41 @@ protected override void OnStartup(StartupEventArgs e)
 
         // Set initial theme based on system settings
         ThemeManager.Apply(OSThemeHelper.AppsUseDarkTheme() ? ApplicationTheme.Dark : ApplicationTheme.Light);
-        SystemEvents.UserPreferenceChanged += (_, _) =>
-            ThemeManager.Apply(OSThemeHelper.AppsUseDarkTheme() ? ApplicationTheme.Dark : ApplicationTheme.Light);
-        UxTheme.ApplyPreferredAppMode();
+        UxTheme.ApplyPreferredAppMode(isTracked: true);
+        SystemEvents.SessionEnding += OnSessionEnding;
 
         // Initialize MessageBox patching
         MessageBoxPatcher.Initialize();
+
+        CheckUpdate();
     }
 
-    private void Application_Startup(object sender, StartupEventArgs e)
+    protected virtual void OnSessionEnding(object sender, SessionEndingEventArgs e)
     {
-        if (!EnsureOSVersion()
-         || !EnsureFirstInstance(e.Args)
-         || !EnsureFolderWritable(SettingHelper.LocalDataPath))
-        {
-            _cleanExit = false;
-            Shutdown();
+        SystemEvents.SessionEnding -= OnSessionEnding;
+
+        // You must unsubscribe from SystemEvents events before your application exits, or the application may crash
+        // https://github.com/QL-Win/QuickLook/issues/1782
+        UxTheme.ApplyPreferredAppMode(isTracked: false);
+    }
+
+    protected override void OnExit(ExitEventArgs e)
+    {
+        // You must unsubscribe from SystemEvents events before your application exits, or the application may crash
+        // https://github.com/QL-Win/QuickLook/issues/1782
+        UxTheme.ApplyPreferredAppMode(isTracked: false);
+
+        base.OnExit(e);
+
+        if (!_cleanExit)
             return;
-        }
 
-        CheckUpdate();
-        RunListener(e);
+        _isRunning.ReleaseMutex();
 
-        // First instance: run and preview this file
-        if (e.Args.Any() && (Directory.Exists(e.Args.First()) || File.Exists(e.Args.First())))
-            PipeServerManager.SendMessage(PipeMessages.Toggle, e.Args.First());
+        PipeServerManager.GetInstance().Dispose();
+        TrayIconManager.GetInstance().Dispose();
+        KeystrokeDispatcher.GetInstance().Dispose();
+        ViewWindowManager.GetInstance().Dispose();
     }
 
     private bool EnsureOSVersion()
@@ -257,6 +282,28 @@ private bool EnsureFolderWritable(string folder)
         return true;
     }
 
+    private bool EnsureFirstInstance(string[] args)
+    {
+        _isRunning = new Mutex(true, "QuickLook.App.Mutex", out bool isFirst);
+
+        if (isFirst)
+            return true;
+
+        // Second instance: preview this file
+        if (args.Any() && (Directory.Exists(args.First()) || File.Exists(args.First())))
+        {
+            PipeServerManager.SendMessage(PipeMessages.Toggle, args.First(), [.. args.Skip(1)]);
+        }
+        // Second instance: duplicate
+        else
+        {
+            MessageBox.Show(TranslationHelper.Get("APP_SECOND_TEXT"), TranslationHelper.Get("APP_SECOND"),
+                MessageBoxButton.OK, MessageBoxImage.Information);
+        }
+
+        return false;
+    }
+
     private void CheckUpdate()
     {
         if (SettingHelper.Get("DisableAutoUpdateCheck", false))
@@ -265,7 +312,7 @@ private void CheckUpdate()
         if (DateTime.Now.Ticks - SettingHelper.Get<long>("LastUpdateTicks") < TimeSpan.FromDays(30).Ticks)
             return;
 
-        Task.Delay(120 * 1000).ContinueWith(_ => Updater.CheckForUpdates(true));
+        _ = Task.Delay(120 * 1000).ContinueWith(_ => Updater.CheckForUpdates(true));
         SettingHelper.Set("LastUpdateTicks", DateTime.Now.Ticks);
     }
 
@@ -284,39 +331,4 @@ private void RunListener(StartupEventArgs e)
         KeystrokeDispatcher.GetInstance();
         PipeServerManager.GetInstance();
     }
-
-    private void App_OnExit(object sender, ExitEventArgs e)
-    {
-        if (!_cleanExit)
-            return;
-
-        _isRunning.ReleaseMutex();
-
-        PipeServerManager.GetInstance().Dispose();
-        TrayIconManager.GetInstance().Dispose();
-        KeystrokeDispatcher.GetInstance().Dispose();
-        ViewWindowManager.GetInstance().Dispose();
-    }
-
-    private bool EnsureFirstInstance(string[] args)
-    {
-        _isRunning = new Mutex(true, "QuickLook.App.Mutex", out bool isFirst);
-
-        if (isFirst)
-            return true;
-
-        // Second instance: preview this file
-        if (args.Any() && (Directory.Exists(args.First()) || File.Exists(args.First())))
-        {
-            PipeServerManager.SendMessage(PipeMessages.Toggle, args.First(), [.. args.Skip(1)]);
-        }
-        // Second instance: duplicate
-        else
-        {
-            MessageBox.Show(TranslationHelper.Get("APP_SECOND_TEXT"), TranslationHelper.Get("APP_SECOND"),
-                MessageBoxButton.OK, MessageBoxImage.Information);
-        }
-
-        return false;
-    }
 }

QuickLook/NativeMethods/UxTheme.cs

@@ -48,7 +48,7 @@ internal static class UxTheme
 
     public enum PreferredAppMode : int { Default, AllowDark, ForceDark, ForceLight, Max };
 
-    public static void ApplyPreferredAppMode()
+    public static void ApplyPreferredAppMode(bool isTracked = true)
     {
         // Enable dark mode for context menus if using dark theme
         if (Environment.OSVersion.Version.Build >= 18362) // Windows 10 1903
@@ -65,20 +65,31 @@ public static void ApplyPreferredAppMode()
                 FlushMenuThemes();
             }
 
-            // Synchronize the theme with system settings
-            SystemEvents.UserPreferenceChanged += (_, _) =>
+            // If you want to follow the system theme
+            if (isTracked)
             {
-                if (OSThemeHelper.SystemUsesDarkTheme())
-                {
-                    SetPreferredAppMode(PreferredAppMode.ForceDark);
-                    FlushMenuThemes();
-                }
-                else
-                {
-                    SetPreferredAppMode(PreferredAppMode.ForceLight);
-                    FlushMenuThemes();
-                }
-            };
+                // Synchronize the theme with system settings
+                SystemEvents.UserPreferenceChanged -= OnUserPreferenceChanged;
+                SystemEvents.UserPreferenceChanged += OnUserPreferenceChanged;
+            }
+            else
+            {
+                SystemEvents.UserPreferenceChanged -= OnUserPreferenceChanged;
+            }
+        }
+
+        static void OnUserPreferenceChanged(object sender, UserPreferenceChangedEventArgs e)
+        {
+            if (OSThemeHelper.SystemUsesDarkTheme())
+            {
+                SetPreferredAppMode(PreferredAppMode.ForceDark);
+                FlushMenuThemes();
+            }
+            else
+            {
+                SetPreferredAppMode(PreferredAppMode.ForceLight);
+                FlushMenuThemes();
+            }
         }
     }
 }