Fall back to managed dialogs when xdg-desktop-portal is unavailable

src/Avalonia.Dialogs/ManagedFileDialogExtensions.cs

@@ -139,9 +139,15 @@ namespace Avalonia.Dialogs
             return builder;
         }
 
+        public static Task<string[]> ShowManagedAsync(this FileDialog dialog, Window parent)
+            => new ManagedSystemDialogImpl<Window>().ShowFileDialogAsync(dialog, parent);
+
+        public static Task<string> ShowManagedAsync(this OpenFolderDialog dialog, Window parent)
+            => new ManagedSystemDialogImpl<Window>().ShowFolderDialogAsync(dialog, parent);
+
         public static Task<string[]> ShowManagedAsync(this OpenFileDialog dialog, Window parent,
             ManagedFileDialogOptions options = null) => ShowManagedAsync<Window>(dialog, parent, options);
-        
+
         public static Task<string[]> ShowManagedAsync<TWindow>(this OpenFileDialog dialog, Window parent,
             ManagedFileDialogOptions options = null) where TWindow : Window, new()
         {

src/Avalonia.FreeDesktop/Avalonia.FreeDesktop.csproj

@@ -2,10 +2,12 @@
 
   <PropertyGroup>
     <TargetFrameworks>net6.0;netstandard2.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\Avalonia.Controls\Avalonia.Controls.csproj" />
+    <ProjectReference Include="..\Avalonia.Dialogs\Avalonia.Dialogs.csproj" />
     <PackageReference Include="Tmds.DBus" Version="0.9.0" />
   </ItemGroup>
   <ItemGroup Label="InternalsVisibleTo">

src/Avalonia.FreeDesktop/DBusHelper.cs

@@ -6,7 +6,7 @@ using Tmds.DBus;
 
 namespace Avalonia.FreeDesktop
 {
-    public class DBusHelper
+    public static class DBusHelper
     {
         /// <summary>
         /// This class uses synchronous execution at DBus connection establishment stage
@@ -14,14 +14,14 @@ namespace Avalonia.FreeDesktop
         /// </summary>
         private class DBusSyncContext : SynchronizationContext
         {
-            private SynchronizationContext _ctx;
-            private object _lock = new object();
+            private readonly object _lock = new();
+            private SynchronizationContext? _ctx;
 
             public override void Post(SendOrPostCallback d, object state)
             {
                 lock (_lock)
                 {
-                    if (_ctx != null)
+                    if (_ctx is not null)
                         _ctx?.Post(d, state);
                     else
                         lock (_lock)
@@ -33,10 +33,9 @@ namespace Avalonia.FreeDesktop
             {
                 lock (_lock)
                 {
-                    if (_ctx != null)
+                    if (_ctx is not null)
                         _ctx?.Send(d, state);
                     else
-
                         d(state);
                 }
             }
@@ -47,15 +46,14 @@ namespace Avalonia.FreeDesktop
                     _ctx = new AvaloniaSynchronizationContext();
             }
         }
-        public static Connection Connection { get; private set; }
 
-        public static Connection TryInitialize(string dbusAddress = null)
+        public static Connection? Connection { get; private set; }
+
+        public static Connection? TryInitialize(string? dbusAddress = null)
+            => Connection ?? TryCreateNewConnection(dbusAddress);
+
+        public static Connection? TryCreateNewConnection(string? dbusAddress = null)
         {
-            return Connection ?? TryCreateNewConnection(dbusAddress);
-        }
-        
-        public static Connection TryCreateNewConnection(string dbusAddress = null)
-        { 
             var oldContext = SynchronizationContext.Current;
             try
             {

src/Avalonia.FreeDesktop/DBusSystemDialog.cs

@@ -5,20 +5,56 @@ using System.Text;
 using System.Threading.Tasks;
 using Avalonia.Controls;
 using Avalonia.Controls.Platform;
+using Avalonia.Dialogs;
+using Avalonia.Logging;
 using Tmds.DBus;
 
 namespace Avalonia.FreeDesktop
 {
     internal class DBusSystemDialog : ISystemDialogImpl
     {
-        private readonly IFileChooser _fileChooser;
+        private readonly IFileChooser? _fileChooser;
+        private bool _isDbusAvailable;
 
         internal DBusSystemDialog()
         {
-            _fileChooser = DBusHelper.Connection.CreateProxy<IFileChooser>("org.freedesktop.portal.Desktop", "/org/freedesktop/portal/desktop");
+            _fileChooser = DBusHelper.Connection?.CreateProxy<IFileChooser>("org.freedesktop.portal.Desktop", "/org/freedesktop/portal/desktop");
+            _isDbusAvailable = _fileChooser is not null;
         }
 
-        public async Task<string[]> ShowFileDialogAsync(FileDialog dialog, Window parent)
+        public async Task<string[]?> ShowFileDialogAsync(FileDialog dialog, Window parent)
+        {
+            if (!_isDbusAvailable)
+                return await dialog.ShowManagedAsync(parent);
+            try
+            {
+                return await ShowNativeFileDialogAsync(dialog, parent);
+            }
+            catch (Exception e)
+            {
+                Logger.TryGet(LogEventLevel.Error, LogArea.X11Platform)?.Log(this, e.Message);
+                _isDbusAvailable = false;
+                return await dialog.ShowManagedAsync(parent);
+            }
+        }
+
+        public async Task<string?> ShowFolderDialogAsync(OpenFolderDialog dialog, Window parent)
+        {
+            if (!_isDbusAvailable)
+                return await dialog.ShowManagedAsync(parent);
+            try
+            {
+                return await ShowNativeFolderDialogAsync(dialog, parent);
+            }
+            catch (Exception e)
+            {
+                Logger.TryGet(LogEventLevel.Error, LogArea.X11Platform)?.Log(this, e.Message);
+                _isDbusAvailable = false;
+                return await dialog.ShowManagedAsync(parent);
+            }
+        }
+
+        private async Task<string[]?> ShowNativeFileDialogAsync(FileDialog dialog, Window parent)
         {
             var parentWindow = $"x11:{parent.PlatformImpl!.Handle.Handle.ToString("X")}";
             ObjectPath objectPath;
@@ -30,38 +66,42 @@ namespace Avalonia.FreeDesktop
             {
                 case OpenFileDialog openFileDialog:
                     options.Add("multiple", openFileDialog.AllowMultiple);
-                    objectPath = await _fileChooser.OpenFileAsync(parentWindow, openFileDialog.Title ?? string.Empty, options);
+                    objectPath = await _fileChooser!.OpenFileAsync(parentWindow, openFileDialog.Title ?? string.Empty, options);
                     break;
                 case SaveFileDialog saveFileDialog:
                     if (saveFileDialog.InitialFileName is not null)
                         options.Add("current_name", saveFileDialog.InitialFileName);
                     if (saveFileDialog.Directory is not null)
                         options.Add("current_folder", Encoding.UTF8.GetBytes(saveFileDialog.Directory));
-                    objectPath = await _fileChooser.SaveFileAsync(parentWindow, saveFileDialog.Title ?? string.Empty, options);
+                    objectPath = await _fileChooser!.SaveFileAsync(parentWindow, saveFileDialog.Title ?? string.Empty, options);
                     break;
             }
 
-            var request = DBusHelper.Connection.CreateProxy<IRequest>("org.freedesktop.portal.Request", objectPath);
-            var tsc = new TaskCompletionSource<string[]>();
-            using var disposable = await request.WatchResponseAsync(x => tsc.TrySetResult(x.results["uris"] as string[]));
+            var request = DBusHelper.Connection!.CreateProxy<IRequest>("org.freedesktop.portal.Request", objectPath);
+            var tsc = new TaskCompletionSource<string[]?>();
+            using var disposable = await request.WatchResponseAsync(x => tsc.SetResult(x.results["uris"] as string[]), tsc.SetException);
             var uris = await tsc.Task;
+            if (uris is null)
+                return null;
             for (var i = 0; i < uris.Length; i++)
                 uris[i] = new Uri(uris[i]).AbsolutePath;
             return uris;
         }
 
-        public async Task<string> ShowFolderDialogAsync(OpenFolderDialog dialog, Window parent)
+        private async Task<string?> ShowNativeFolderDialogAsync(OpenFolderDialog dialog, Window parent)
         {
             var parentWindow = $"x11:{parent.PlatformImpl!.Handle.Handle.ToString("X")}";
             var options = new Dictionary<string, object>
             {
                 { "directory", true }
             };
-            var objectPath = await _fileChooser.OpenFileAsync(parentWindow, dialog.Title ?? string.Empty, options);
-            var request = DBusHelper.Connection.CreateProxy<IRequest>("org.freedesktop.portal.Request", objectPath);
-            var tsc = new TaskCompletionSource<string[]>();
-            using var disposable = await request.WatchResponseAsync(x => tsc.TrySetResult(x.results["uris"] as string[]));
+            var objectPath = await _fileChooser!.OpenFileAsync(parentWindow, dialog.Title ?? string.Empty, options);
+            var request = DBusHelper.Connection!.CreateProxy<IRequest>("org.freedesktop.portal.Request", objectPath);
+            var tsc = new TaskCompletionSource<string[]?>();
+            using var disposable = await request.WatchResponseAsync(x => tsc.SetResult(x.results["uris"] as string[]), tsc.SetException);
             var uris = await tsc.Task;
+            if (uris is null)
+                return null;
             return uris.Length != 1 ? string.Empty : new Uri(uris[0]).AbsolutePath;
         }
 
@@ -71,7 +111,7 @@ namespace Avalonia.FreeDesktop
             for (var i = 0; i < filters.Length; i++)
             {
                 var extensions = dialog.Filters[i].Extensions.Select(static x => (0u, x)).ToArray();
-                filters[i] = (dialog.Filters[i].Name, extensions);
+                filters[i] = (dialog.Filters[i].Name ?? string.Empty, extensions);
             }
 
             return filters;

src/Avalonia.X11/X11Platform.cs

@@ -15,7 +15,6 @@ using Avalonia.Platform;
 using Avalonia.Rendering;
 using Avalonia.X11;
 using Avalonia.X11.Glx;
-using Avalonia.X11.NativeDialogs;
 using static Avalonia.X11.XLib;
 
 namespace Avalonia.X11
@@ -80,7 +79,7 @@ namespace Avalonia.X11
                 .Bind<IClipboard>().ToConstant(new X11Clipboard(this))
                 .Bind<IPlatformSettings>().ToConstant(new PlatformSettingsStub())
                 .Bind<IPlatformIconLoader>().ToConstant(new X11IconLoader(Info))
-                .Bind<ISystemDialogImpl>().ToConstant(new GtkSystemDialog())
+                .Bind<ISystemDialogImpl>().ToConstant(new DBusSystemDialog())
                 .Bind<IMountedVolumeInfoProvider>().ToConstant(new LinuxMountedVolumeInfoProvider())
                 .Bind<IPlatformLifetimeEventsImpl>().ToConstant(new X11PlatformLifetimeEvents(this));
             
@@ -209,10 +208,10 @@ namespace Avalonia
         public bool OverlayPopups { get; set; }
 
         /// <summary>
-        /// Enables global menu support on Linux desktop environments where it's supported (e. g. XFCE and MATE with plugin, KDE, etc).
-        /// The default value is false.
+        /// Enables native file dialogs as well as global menu support on Linux desktop environments where it's supported (e. g. XFCE and MATE with plugin, KDE, etc).
+        /// The default value is true.
         /// </summary>
-        public bool UseDBusMenu { get; set; }
+        public bool UseDBusMenu { get; set; } = true;
 
         /// <summary>
         /// Deferred renderer would be used when set to true. Immediate renderer when set to false. The default value is true.