Fix ClassicDesktop Lifetime so that ShutdownRequested event is raised…

src/Avalonia.Controls/ApiCompatBaseline.txt

@@ -36,6 +36,7 @@ CannotRemoveBaseTypeOrInterface : Type 'Avalonia.Controls.WindowBase' does not i
 InterfacesShouldHaveSameMembers : Interface member 'public System.EventHandler<Avalonia.Controls.ApplicationLifetimes.ShutdownRequestedEventArgs> Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.ShutdownRequested' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.add_ShutdownRequested(System.EventHandler<Avalonia.Controls.ApplicationLifetimes.ShutdownRequestedEventArgs>)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.remove_ShutdownRequested(System.EventHandler<Avalonia.Controls.ApplicationLifetimes.ShutdownRequestedEventArgs>)' is present in the implementation but not in the contract.
+InterfacesShouldHaveSameMembers : Interface member 'public System.Boolean Avalonia.Controls.ApplicationLifetimes.IClassicDesktopStyleApplicationLifetime.TryShutdown(System.Int32)' is present in the implementation but not in the contract.
 CannotRemoveBaseTypeOrInterface : Type 'Avalonia.Controls.Embedding.EmbeddableControlRoot' does not implement interface 'Avalonia.Utilities.IWeakSubscriber<Avalonia.Controls.ResourcesChangedEventArgs>' in the implementation but it does in the contract.
 MembersMustExist : Member 'public System.Action<Avalonia.Size> Avalonia.Controls.Embedding.Offscreen.OffscreenTopLevelImplBase.Resized.get()' does not exist in the implementation but it does exist in the contract.
 MembersMustExist : Member 'public void Avalonia.Controls.Embedding.Offscreen.OffscreenTopLevelImplBase.Resized.set(System.Action<Avalonia.Size>)' does not exist in the implementation but it does exist in the contract.
@@ -62,4 +63,4 @@ InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platfor
 MembersMustExist : Member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size)' does not exist in the implementation but it does exist in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public void Avalonia.Platform.IWindowImpl.Resize(Avalonia.Size, Avalonia.Platform.PlatformResizeReason)' is present in the implementation but not in the contract.
 InterfacesShouldHaveSameMembers : Interface member 'public Avalonia.Platform.ITrayIconImpl Avalonia.Platform.IWindowingPlatform.CreateTrayIcon()' is present in the implementation but not in the contract.
-Total Issues: 63
+Total Issues: 64

src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs

@@ -76,36 +76,21 @@ private void HandleWindowClosed(Window window)
                 return;
 
             if (ShutdownMode == ShutdownMode.OnLastWindowClose && _windows.Count == 0)
-                Shutdown();
-            else if (ShutdownMode == ShutdownMode.OnMainWindowClose && window == MainWindow)
-                Shutdown();
+                TryShutdown();
+            else if (ShutdownMode == ShutdownMode.OnMainWindowClose && ReferenceEquals(window, MainWindow))
+                TryShutdown();
         }
 
         public void Shutdown(int exitCode = 0)
         {
-            if (_isShuttingDown)
-                throw new InvalidOperationException("Application is already shutting down.");
-
-            _exitCode = exitCode;
-            _isShuttingDown = true;
+            DoShutdown(new ShutdownRequestedEventArgs(), true, exitCode);
+        }
 
-            try
-            {
-                foreach (var w in Windows)
-                    w.Close();
-                var e = new ControlledApplicationLifetimeExitEventArgs(exitCode);
-                Exit?.Invoke(this, e);
-                _exitCode = e.ApplicationExitCode;                
-            }
-            finally
-            {
-                _cts?.Cancel();
-                _cts = null;
-                _isShuttingDown = false;
-            }
+        public bool TryShutdown(int exitCode = 0)
+        {
+            return DoShutdown(new ShutdownRequestedEventArgs(), false, exitCode);
         }
 
-
         public int Start(string[] args)
         {
             Startup?.Invoke(this, new ControlledApplicationLifetimeStartupEventArgs(args));
@@ -114,7 +99,10 @@ public int Start(string[] args)
 
             if(options != null && options.ProcessUrlActivationCommandLine && args.Length > 0)
             {
-                ((IApplicationPlatformEvents)Application.Current).RaiseUrlsOpened(args);
+                if (Application.Current is IApplicationPlatformEvents events)
+                {
+                    events.RaiseUrlsOpened(args);
+                }
             }
 
             var lifetimeEvents = AvaloniaLocator.Current.GetService<IPlatformLifetimeEventsImpl>(); 
@@ -145,23 +133,57 @@ public void Dispose()
             if (_activeLifetime == this)
                 _activeLifetime = null;
         }
-        
-        private void OnShutdownRequested(object sender, ShutdownRequestedEventArgs e)
+
+        private bool DoShutdown(ShutdownRequestedEventArgs e, bool force = false, int exitCode = 0)
         {
-            ShutdownRequested?.Invoke(this, e);
+            if (!force)
+            {
+                ShutdownRequested?.Invoke(this, e);
 
-            if (e.Cancel)
-                return;
+                if (e.Cancel)
+                    return false;
+
+                if (_isShuttingDown)
+                    throw new InvalidOperationException("Application is already shutting down.");
+            }
+
+            _exitCode = exitCode;
+            _isShuttingDown = true;
 
-            // When an OS shutdown request is received, try to close all non-owned windows. Windows can cancel
-            // shutdown by setting e.Cancel = true in the Closing event. Owned windows will be shutdown by their
-            // owners.
-            foreach (var w in Windows)
-                if (w.Owner is null)
-                    w.Close();
-            if (Windows.Count > 0)
-                e.Cancel = true;
+            try
+            {
+                // When an OS shutdown request is received, try to close all non-owned windows. Windows can cancel
+                // shutdown by setting e.Cancel = true in the Closing event. Owned windows will be shutdown by their
+                // owners.
+                foreach (var w in Windows)
+                {
+                    if (w.Owner is null)
+                    {
+                        w.Close();
+                    }
+                }
+
+                if (!force && Windows.Count > 0)
+                {
+                    e.Cancel = true;
+                    return false;
+                }
+
+                var args = new ControlledApplicationLifetimeExitEventArgs(exitCode);
+                Exit?.Invoke(this, args);
+                _exitCode = args.ApplicationExitCode;                
+            }
+            finally
+            {
+                _cts?.Cancel();
+                _cts = null;
+                _isShuttingDown = false;
+            }
+
+            return true;
         }
+
+        private void OnShutdownRequested(object sender, ShutdownRequestedEventArgs e) => DoShutdown(e);
     }
 
     public class ClassicDesktopStyleApplicationLifetimeOptions

src/Avalonia.Controls/ApplicationLifetimes/IClassicDesktopStyleApplicationLifetime.cs

@@ -9,6 +9,12 @@ namespace Avalonia.Controls.ApplicationLifetimes
     /// </summary>
     public interface IClassicDesktopStyleApplicationLifetime : IControlledApplicationLifetime
     {
+        /// <summary>
+        /// Tries to Shutdown the application. <see cref="ShutdownRequested" /> event can be used to cancel the shutdown.
+        /// </summary>
+        /// <param name="exitCode">An integer exit code for an application. The default exit code is 0.</param>
+        bool TryShutdown(int exitCode = 0);
+
         /// <summary>
         /// Gets the arguments passed to the
         /// <see cref="ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime{T}(T, string[], ShutdownMode)"/>

src/Avalonia.Native/AvaloniaNativeMenuExporter.cs

@@ -133,9 +133,13 @@ private void PopulateStandardOSXMenuItems(NativeMenu appMenu)
             var quitItem = new NativeMenuItem("Quit") { Gesture = new KeyGesture(Key.Q, KeyModifiers.Meta) };
             quitItem.Click += (_, _) =>
             {
-                if (Application.Current is { ApplicationLifetime: IControlledApplicationLifetime lifetime })
+                if (Application.Current is { ApplicationLifetime: IClassicDesktopStyleApplicationLifetime lifetime })
                 {
-                    lifetime.Shutdown();
+                    lifetime.TryShutdown();
+                }
+                else if(Application.Current is {ApplicationLifetime: IControlledApplicationLifetime controlledLifetime})
+                {
+                    controlledLifetime.Shutdown();
                 }
             };
 

tests/Avalonia.Controls.UnitTests/DesktopStyleApplicationLifetimeTests.cs

@@ -1,9 +1,7 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Platform;
-using Avalonia.Threading;
 using Avalonia.UnitTests;
 using Moq;
 using Xunit;
@@ -57,7 +55,7 @@ public void Should_Only_Exit_On_Explicit_Exit()
 
                 var hasExit = false;
 
-                lifetime.Exit += (s, e) => hasExit = true;
+                lifetime.Exit += (_, _) => hasExit = true;
 
                 var windowA = new Window();
 
@@ -91,7 +89,7 @@ public void Should_Exit_After_MainWindow_Closed()
 
                 var hasExit = false;
 
-                lifetime.Exit += (s, e) => hasExit = true;
+                lifetime.Exit += (_, _) => hasExit = true;
 
                 var mainWindow = new Window();
 
@@ -119,7 +117,7 @@ public void Should_Exit_After_Last_Window_Closed()
 
                 var hasExit = false;
 
-                lifetime.Exit += (s, e) => hasExit = true;
+                lifetime.Exit += (_, _) => hasExit = true;
 
                 var windowA = new Window();
 
@@ -226,7 +224,7 @@ public void Should_Allow_Canceling_Shutdown_Via_ShutdownRequested_Event()
 
                 window.Show();
 
-                lifetime.ShutdownRequested += (s, e) =>
+                lifetime.ShutdownRequested += (_, e) =>
                 {
                     e.Cancel = true;
                     ++raised;
@@ -238,5 +236,171 @@ public void Should_Allow_Canceling_Shutdown_Via_ShutdownRequested_Event()
                 Assert.Equal(new[] { window }, lifetime.Windows);
             }
         }
+
+        [Fact]
+        public void MainWindow_Closed_Shutdown_Should_Be_Cancellable()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
+            {
+                lifetime.ShutdownMode = ShutdownMode.OnMainWindowClose;
+
+                var hasExit = false;
+
+                lifetime.Exit += (_, _) => hasExit = true;
+
+                var mainWindow = new Window();
+
+                mainWindow.Show();
+
+                lifetime.MainWindow = mainWindow;
+
+                var window = new Window();
+
+                window.Show();
+
+                var raised = 0;
+
+                lifetime.ShutdownRequested += (_, e) =>
+                {
+                    e.Cancel = true;
+                    ++raised;
+                };
+
+                mainWindow.Close();
+
+                Assert.Equal(1, raised);
+                Assert.False(hasExit);
+            }
+        }
+
+        [Fact]
+        public void LastWindow_Closed_Shutdown_Should_Be_Cancellable()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
+            {
+                lifetime.ShutdownMode = ShutdownMode.OnLastWindowClose;
+
+                var hasExit = false;
+
+                lifetime.Exit += (_, _) => hasExit = true;
+
+                var windowA = new Window();
+
+                windowA.Show();
+
+                var windowB = new Window();
+
+                windowB.Show();
+
+                var raised = 0;
+
+                lifetime.ShutdownRequested += (_, e) =>
+                {
+                    e.Cancel = true;
+                    ++raised;
+                };
+
+                windowA.Close();
+
+                Assert.False(hasExit);
+
+                windowB.Close();
+
+                Assert.Equal(1, raised);
+                Assert.False(hasExit);
+            }
+        }
+
+        [Fact]
+        public void TryShutdown_Cancellable_By_Preventing_Window_Close()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
+            {
+                var hasExit = false;
+
+                lifetime.Exit += (_, _) => hasExit = true;
+
+                var windowA = new Window();
+
+                windowA.Show();
+
+                var windowB = new Window();
+
+                windowB.Show();
+
+                var raised = 0;
+
+                windowA.Closing += (_, e) =>
+                {
+                    e.Cancel = true;
+                    ++raised;
+                };
+
+                lifetime.TryShutdown();
+
+                Assert.Equal(1, raised);
+                Assert.False(hasExit);
+            }
+        }
+
+        [Fact]
+        public void Shutdown_NotCancellable_By_Preventing_Window_Close()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
+            {
+                var hasExit = false;
+
+                lifetime.Exit += (_, _) => hasExit = true;
+
+                var windowA = new Window();
+
+                windowA.Show();
+
+                var windowB = new Window();
+
+                windowB.Show();
+
+                var raised = 0;
+
+                windowA.Closing += (_, e) =>
+                {
+                    e.Cancel = true;
+                    ++raised;
+                };
+
+                lifetime.Shutdown();
+
+                Assert.Equal(1, raised);
+                Assert.True(hasExit);
+            }
+        }
+
+        [Fact]
+        public void Shutdown_Doesnt_Raise_Shutdown_Requested()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            using(var lifetime = new ClassicDesktopStyleApplicationLifetime())
+            {
+                var hasExit = false;
+
+                lifetime.Exit += (_, _) => hasExit = true;
+
+                var raised = 0;
+
+                lifetime.ShutdownRequested += (_, _) =>
+                {
+                    ++raised;
+                };
+
+                lifetime.Shutdown();
+
+                Assert.Equal(0, raised);
+                Assert.True(hasExit);
+            }
+        }
     }
 }