Add an event so that users can detect when an Application icon is clicked

native/Avalonia.Native/src/OSX/app.mm

@@ -43,6 +43,22 @@ - (void)applicationDidFinishLaunching:(NSNotification *)notification
     [[NSRunningApplication currentApplication] activateWithOptions:NSApplicationActivateIgnoringOtherApps];
 }
 
+-(BOOL)applicationShouldHandleReopen:(NSApplication *)sender hasVisibleWindows:(BOOL)flag
+{
+    _events->OnReopen();
+    return YES;
+}
+
+- (void)applicationDidHide:(NSNotification *)notification
+{
+    _events->OnHide();
+}
+
+- (void)applicationDidUnhide:(NSNotification *)notification
+{
+    _events->OnUnhide();
+}
+
 - (void)application:(NSApplication *)sender openFiles:(NSArray<NSString *> *)filenames
 {
     auto array = CreateAvnStringArray(filenames);
@@ -123,6 +139,13 @@ extern void ReleaseAvnAppEvents()
     }
 }
 
+HRESULT AvnApplicationCommands::UnhideApp()
+{
+    START_COM_CALL;
+    [[NSApplication sharedApplication] unhide:[NSApp delegate]];
+    return S_OK;
+}
+
 HRESULT AvnApplicationCommands::HideApp()
 {
     START_COM_CALL;

native/Avalonia.Native/src/OSX/common.h

@@ -101,6 +101,7 @@ class AvnApplicationCommands : public ComSingleObject<IAvnApplicationCommands, &
 public:
     FORWARD_IUNKNOWN()
 
+    virtual HRESULT UnhideApp() override;
     virtual HRESULT HideApp() override;
     virtual HRESULT ShowAll() override;
     virtual HRESULT HideOthers() override;

src/Avalonia.Controls/ApplicationLifetimes/ActivatedEventArgs.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace Avalonia.Controls.ApplicationLifetimes;
+
+/// <summary>
+/// Event args for an Application Lifetime Activated or Deactivated events.
+/// </summary>
+public class ActivatedEventArgs : EventArgs
+{
+    /// <summary>
+    /// Ctor for ActivatedEventArgs
+    /// </summary>
+    /// <param name="kind">The <see cref="ActivationKind"/> that this event represents</param>
+    public ActivatedEventArgs(ActivationKind kind)
+    {
+        Kind = kind;
+    }
+
+    /// <summary>
+    /// The <see cref="ActivationKind"/> that this event represents.
+    /// </summary>
+    public ActivationKind Kind { get; }
+}

src/Avalonia.Controls/ApplicationLifetimes/ActivationKind.cs

@@ -0,0 +1,25 @@
+namespace Avalonia.Controls.ApplicationLifetimes;
+
+public enum ActivationKind
+{
+    /// <summary>
+    /// When the application is passed a URI to open.
+    /// </summary>
+    OpenUri = 20, 
+
+    /// <summary>
+    /// When the application is asked to reopen.
+    /// An example of this is on MacOS when all the windows are closed,
+    /// application continues to run in the background and the user clicks
+    /// the application's dock icon. 
+    /// </summary>
+    Reopen = 30,
+
+    /// <summary>
+    /// When the application enters or leaves a background state.
+    /// An example is when on MacOS the user hides or shows and application (not window),
+    /// or when a browser application switchs tabs or when a mobile applications goes into
+    /// the background.
+    /// </summary>
+    Background = 40
+}

src/Avalonia.Controls/ApplicationLifetimes/ClassicDesktopStyleApplicationLifetime.cs

@@ -211,11 +211,16 @@ public static class ClassicDesktopStyleApplicationLifetimeExtensions
         public static int StartWithClassicDesktopLifetime(
             this AppBuilder builder, string[] args, ShutdownMode shutdownMode = ShutdownMode.OnLastWindowClose)
         {
-            var lifetime = new ClassicDesktopStyleApplicationLifetime()
+            var lifetime = AvaloniaLocator.Current.GetService<ClassicDesktopStyleApplicationLifetime>();
+
+            if (lifetime == null)
             {
-                Args = args,
-                ShutdownMode = shutdownMode
-            };
+                lifetime = new ClassicDesktopStyleApplicationLifetime();
+            }
+
+            lifetime.Args = args;
+            lifetime.ShutdownMode = shutdownMode;
+
             builder.SetupWithLifetime(lifetime);
             return lifetime.Start(args);
         }

src/Avalonia.Controls/ApplicationLifetimes/IActivatableApplicationLifetime.cs

@@ -0,0 +1,35 @@
+using System;
+
+namespace Avalonia.Controls.ApplicationLifetimes;
+
+/// <summary>
+/// An interface for ApplicationLifetimes where the application can be Activated and Deactivated.
+/// </summary>
+public interface IActivatableApplicationLifetime
+{
+    /// <summary>
+    /// An event that is raised when the application is Activated for various reasons
+    /// as described by the <see cref="ActivationKind"/> enumeration.
+    /// </summary>
+    event EventHandler<ActivatedEventArgs> Activated;
+
+    /// <summary>
+    /// An event that is raised when the application is Deactivated for various reasons
+    /// as described by the <see cref="ActivationKind"/> enumeration.
+    /// </summary>
+    event EventHandler<ActivatedEventArgs> Deactivated;
+
+    /// <summary>
+    /// Tells the application that it should attempt to leave its background state.
+    /// For example on OSX this would be [NSApp unhide]
+    /// </summary>
+    /// <returns>true if it was possible and the platform supports this. false otherwise</returns>
+    public bool TryLeaveBackground();
+
+    /// <summary>
+    /// Tells the application that it should attempt to enter its background state.
+    /// For example on OSX this would be [NSApp hide]
+    /// </summary>
+    /// <returns>true if it was possible and the platform supports this. false otherwise</returns>
+    public bool TryEnterBackground();
+}

src/Avalonia.Controls/ApplicationLifetimes/ProtocolActivatedEventArgs.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace Avalonia.Controls.ApplicationLifetimes;
+
+public class ProtocolActivatedEventArgs : ActivatedEventArgs
+{
+    public ProtocolActivatedEventArgs(ActivationKind kind, Uri uri) : base(kind)
+    {
+        Uri = uri;
+    }
+
+    public Uri Uri { get; }
+}

src/Avalonia.Controls/Platform/INativeApplicationCommands.cs

@@ -5,6 +5,7 @@ namespace Avalonia.Controls.Platform
     /// </summary>
     internal interface INativeApplicationCommands
     {
+        void ShowApp();
         void HideApp();
         void ShowAll();
         void HideOthers();

src/Avalonia.Native/AvaloniaNativeApplicationPlatform.cs

@@ -13,6 +13,38 @@ internal class AvaloniaNativeApplicationPlatform : NativeCallbackBase, IAvnAppli
         void IAvnApplicationEvents.FilesOpened(IAvnStringArray urls)
         {
             ((IApplicationPlatformEvents)Application.Current).RaiseUrlsOpened(urls.ToStringArray());
+
+            if (Application.Current?.ApplicationLifetime is MacOSClassicDesktopStyleApplicationLifetime lifetime)
+            {
+                foreach (var url in urls.ToStringArray())
+                {
+                    lifetime.RaiseUrl(new Uri(url));
+                }
+            }
+        }
+
+        void IAvnApplicationEvents.OnReopen()
+        {
+            if (Application.Current?.ApplicationLifetime is MacOSClassicDesktopStyleApplicationLifetime lifetime)
+            {
+                lifetime.RaiseActivated(ActivationKind.Reopen);    
+            }
+        }
+
+        void IAvnApplicationEvents.OnHide()
+        {
+            if (Application.Current?.ApplicationLifetime is MacOSClassicDesktopStyleApplicationLifetime lifetime)
+            {
+                lifetime.RaiseDeactivated(ActivationKind.Background);    
+            }
+        }
+
+        void IAvnApplicationEvents.OnUnhide()
+        {
+            if (Application.Current?.ApplicationLifetime is MacOSClassicDesktopStyleApplicationLifetime lifetime)
+            {
+                lifetime.RaiseActivated(ActivationKind.Background);    
+            }
         }
 
         public int TryShutdown()

src/Avalonia.Native/AvaloniaNativePlatformExtensions.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using Avalonia.Controls;
+using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Native;
 
 namespace Avalonia
@@ -24,6 +25,9 @@ public static AppBuilder UseAvaloniaNative(this AppBuilder builder)
                     });
             });
 
+            AvaloniaLocator.CurrentMutable.Bind<ClassicDesktopStyleApplicationLifetime>()
+                .ToConstant(new MacOSClassicDesktopStyleApplicationLifetime());
+
             return builder;
         }
     }

src/Avalonia.Native/MacOSClassicDesktopStyleApplicationLifetime.cs

@@ -0,0 +1,50 @@
+using System;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Controls.Platform;
+
+namespace Avalonia.Native;
+
+#nullable enable
+
+internal class MacOSClassicDesktopStyleApplicationLifetime : ClassicDesktopStyleApplicationLifetime,
+    IActivatableApplicationLifetime
+{
+    /// <inheritdoc />
+    public event EventHandler<ActivatedEventArgs>? Activated;
+
+    /// <inheritdoc />
+    public event EventHandler<ActivatedEventArgs>? Deactivated;
+
+    /// <inheritdoc />
+    public bool TryLeaveBackground()
+    {
+        var nativeApplicationCommands = AvaloniaLocator.Current.GetService<INativeApplicationCommands>();
+        nativeApplicationCommands?.ShowApp();
+
+        return true;
+    }
+
+    /// <inheritdoc />
+    public bool TryEnterBackground()
+    {
+        var nativeApplicationCommands = AvaloniaLocator.Current.GetService<INativeApplicationCommands>();
+        nativeApplicationCommands?.HideApp();
+
+        return true;
+    }
+
+    internal void RaiseUrl(Uri uri)
+    {
+        Activated?.Invoke(this, new ProtocolActivatedEventArgs(ActivationKind.OpenUri, uri));
+    }
+
+    internal void RaiseActivated(ActivationKind kind)
+    {
+        Activated?.Invoke(this, new ActivatedEventArgs(kind));
+    }
+
+    internal void RaiseDeactivated(ActivationKind kind)
+    {
+        Deactivated?.Invoke(this, new ActivatedEventArgs(kind));
+    }
+}

src/Avalonia.Native/MacOSNativeMenuCommands.cs

@@ -13,6 +13,11 @@ public MacOSNativeMenuCommands(IAvnApplicationCommands commands)
             _commands = commands;
         }
 
+        public void ShowApp()
+        {
+            _commands.UnhideApp();
+        }
+
         public void HideApp()
         {
             _commands.HideApp();
@@ -28,7 +33,6 @@ public void HideOthers()
             _commands.HideOthers();
         }
 
-
         public static readonly AttachedProperty<bool> IsServicesSubmenuProperty =
             AvaloniaProperty.RegisterAttached<MacOSNativeMenuCommands, NativeMenu, bool>("IsServicesSubmenu", false);
     }

src/Avalonia.Native/avn.idl

@@ -1087,11 +1087,15 @@ interface IAvnApplicationEvents : IUnknown
 {
      void FilesOpened (IAvnStringArray* urls);
      bool TryShutdown();
+     void OnReopen ();
+     void OnHide ();
+     void OnUnhide ();
 }
 
 [uuid(b4284791-055b-4313-8c2e-50f0a8c72ce9)]
 interface IAvnApplicationCommands : IUnknown
 {
+    HRESULT UnhideApp();
     HRESULT HideApp();
     HRESULT ShowAll();
     HRESULT HideOthers();