UI: Update to Avalonia 12, .NET 10 and replace ReactiveUI with MVVM community toolkit

.github/workflows/build.yml

@@ -12,9 +12,8 @@ jobs:
     strategy:
       matrix:
         platform: [
-          {netversion: 6.x, targetframework: net6.0, aot: false, singleFile: true, aotString: ""},
-          {netversion: 8.x, targetframework: net8.0, aot: false, singleFile: true, aotString: ""},
-          {netversion: 8.x, targetframework: net8.0, aot: true, singleFile: false, aotString: " - AoT"}
+          {netversion: 10.x, targetframework: net10.0, aot: false, singleFile: true, aotString: ""},
+          {netversion: 10.x, targetframework: net10.0, aot: true, singleFile: false, aotString: " - AoT"}
         ]
       fail-fast: false
     runs-on: windows-2025-vs2026
@@ -84,7 +83,7 @@ jobs:
       - name: Install .NET Core
         uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: 8.x
+          dotnet-version: 10.x
 
       - name: Install dependencies
         run: |
@@ -130,7 +129,7 @@ jobs:
       - name: Install .NET Core
         uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: 8.x
+          dotnet-version: 10.x
 
       - name: Install dependencies
         run: |
@@ -181,7 +180,7 @@ jobs:
       - name: Install .NET Core
         uses: actions/setup-dotnet@v5
         with:
-          dotnet-version: 8.x
+          dotnet-version: 10.x
 
       - name: Install dependencies
         run: |

.github/workflows/dotnet-format-check.yml

@@ -17,7 +17,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v5
       with:
-        dotnet-version: 8.0.x
+        dotnet-version: 10.0.x
     - name: Restore dependencies
       run: dotnet restore
     - name: Format

COMPILING.md

@@ -1,22 +1,22 @@
 ## Windows
 
-1) Open the solution in Visual Studio 2022
+1) Open the solution in Visual Studio (2022 or 2026)
 2) Compile as `Release`/`x64`
 3) Set the startup project to the `UI` project and run
 
 ## Linux
 
 To build under Linux you need a version of Clang or GCC that supports C++17.  
 
-Additionally, SDL2 and the [.NET 8 SDK](https://learn.microsoft.com/en-us/dotnet/core/install/linux) must also be installed.
+Additionally, SDL2 and the [.NET 10 SDK](https://learn.microsoft.com/en-us/dotnet/core/install/linux) must also be installed.
 
-Once SDL2 and the .NET 8 SDK are installed, run `make` to compile with Clang.  
+Once SDL2 and the .NET 10 SDK are installed, run `make` to compile with Clang.  
 To compile with GCC instead, use `USE_GCC=true make`.  
 **Note:** Mesen usually runs faster when built with Clang instead of GCC.
 
 
 ## macOS
 
-To build macOS, install SDL2 (i.e via Homebrew) and the [.NET 8 SDK](https://dotnet.microsoft.com/en-us/download/dotnet/8.0).  
+To build macOS, install SDL2 (i.e via Homebrew) and the [.NET 10 SDK](https://dotnet.microsoft.com/en-us/download/dotnet/10.0).  
 
-Once SDL2 and the .NET 8 SDK are installed, run `make`.
+Once SDL2 and the .NET 10 SDK are installed, run `make`.

Linux/appimage/appimage-arm64.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-export PUBLISHFLAGS="-r linux-arm64 --no-self-contained false -p:PublishSingleFile=true -p:PublishReadyToRun=true"
+export PUBLISHFLAGS="-r linux-arm64 -p:PublishSingleFile=true -p:PublishReadyToRun=true"
 make -j$(nproc) -O LTO=true STATICLINK=true SYSTEM_LIBEVDEV=false
 
 curl -SL https://github.com/AppImage/AppImageKit/releases/download/continuous/appimagetool-aarch64.AppImage -o appimagetool

Linux/appimage/appimage.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 
-export PUBLISHFLAGS="-r linux-x64 --no-self-contained false -p:PublishSingleFile=true -p:PublishReadyToRun=true"
+export PUBLISHFLAGS="-r linux-x64 -p:PublishSingleFile=true -p:PublishReadyToRun=true"
 make -j$(nproc) -O LTO=true STATICLINK=true SYSTEM_LIBEVDEV=false
 
 curl -SL https://github.com/AppImage/AppImageKit/releases/download/continuous/appimagetool-x86_64.AppImage -o appimagetool

README.md

@@ -12,27 +12,20 @@ We are currently just doing development builds. When we launch stable releases,
 
 [![Mesen](https://github.com/nesdev-org/MesenCE/actions/workflows/build.yml/badge.svg)](https://github.com/nesdev-org/MesenCE/actions/workflows/build.yml)
 
-#### <ins>Native builds</ins> (recommended) ####
+#### <ins>Recommended</ins>
 
-These builds don't require .NET to be installed. They load more quickly and are recommended over the .NET builds.  
-
-* [Windows 10 / 11](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28Windows%20-%20net8.0%20-%20AoT%29.zip)  
+* [Windows 10 / 11](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28Windows%20-%20net10.0%20-%20AoT%29.zip)  
 * [Linux x64](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28Linux%20-%20ubuntu-22.04%20-%20clang_aot%29.zip)  (requires **SDL2**)  
 * [Linux ARM64](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28Linux%20-%20ubuntu-22.04-arm%20-%20clang_aot%29.zip)  (requires **SDL2**)  
 * [macOS - Intel](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28macOS%20-%20macos-15-intel%20-%20clang_aot%29.zip)  (requires **SDL2**)  
 * [macOS - Apple Silicon](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28macOS%20-%20macos-15%20-%20clang_aot%29.zip)  (requires **SDL2**)  
 
-#### <ins>.NET builds</ins> ####
-
-These builds use .NET, which for some builds comes bundled and for others must be installed.  
-They all require **.NET 8** except the Windows 7 / 8 build, which requires **.NET 6**.  
-For Linux and macOS, **SDL2** must also be installed. For AppImage builds, **FUSE** (such as libfuse2) must be installed.
+#### <ins>AppImages</ins> (Linux)
 
-* [Windows 7 / 8](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28Windows%20-%20net6.0%29.zip)  (requires **.NET 6**)
-* [Linux x64 - AppImage](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20(Linux%20x64%20-%20AppImage).zip)  (requires **FUSE** and **SDL2**)
-* [Linux ARM64](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20%28Linux%20-%20ubuntu-22.04-arm%20-%20clang%29.zip)  (requires **.NET 8** and **SDL2**)
-* [Linux ARM64 - AppImage](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20(Linux%20ARM64%20-%20AppImage).zip)  (requires **FUSE** and **SDL2**)
+For AppImage builds, **FUSE** (such as libfuse2) and **SDL2** must be installed.
 
+* [Linux x64 (AppImage)](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20(Linux%20x64%20-%20AppImage).zip)
+* [Linux ARM64 (AppImage)](https://nightly.link/nesdev-org/MesenCE/workflows/build/master/Mesen%20(Linux%20ARM64%20-%20AppImage).zip)
 
 #### <ins>Notes</ins> ####
 
@@ -53,7 +46,7 @@ See [CONTRIBUTING.md](CONTRIBUTING.md)
 
 Mesen is available under the GPL V3 license.  Full text here: <http://www.gnu.org/licenses/gpl-3.0.en.html>
 
-Copyright (C) 2014-2025 Sour, 2026 contributors
+Copyright (C) 2014-2026 Sour, 2026 contributors
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by

UI/.filenesting.json

@@ -0,0 +1,19 @@
+{
+  "help": "https://go.microsoft.com/fwlink/?linkid=866610",
+  "root": true,
+
+  "dependentFileProviders": {
+    "add": {
+      "extensionToExtension": {
+        "add": {
+          ".cs": [
+            ".axaml.cs"
+          ],
+          ".designer.cs": [
+            ".resx"
+          ]
+        }
+      }
+    }
+  }
+}

UI/App.axaml

@@ -32,6 +32,7 @@
 		<l:EnumConverter x:Key="Enum" />
 		<u:FontNameConverter x:Key="FontNameConverter" />
 		<u:NullTextConverter x:Key="NullTextConverter" />
+		<u:EnumMatchConverter x:Key="EnumMatchConverter" />
 
 		<VisualBrush x:Key="ViewerBgBrush" TileMode="Tile" Stretch="None" AlignmentX="Left" AlignmentY="Top" SourceRect="0,0,5,5" DestinationRect="0,0,5,5">
 			<VisualBrush.Visual>

UI/App.axaml.cs

@@ -34,6 +34,9 @@ public override void Initialize()
 				e.Handled = true;
 			};
 
+#if DEBUG
+			this.AttachDeveloperTools();
+#endif
 			AvaloniaXamlLoader.Load(this);
 			ResourceHelper.LoadResources();
 		}

UI/Config/AudioConfig.cs

@@ -1,6 +1,5 @@
-using Mesen.Interop;
-using ReactiveUI;
-using ReactiveUI.Fody.Helpers;
+using CommunityToolkit.Mvvm.ComponentModel;
+using Mesen.Interop;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -10,54 +9,54 @@
 
 namespace Mesen.Config
 {
-	public class AudioConfig : BaseConfig<AudioConfig>
+	public partial class AudioConfig : BaseConfig<AudioConfig>
 	{
-		[Reactive] public string AudioDevice { get; set; } = "";
-		[Reactive] public bool EnableAudio { get; set; } = true;
-		[Reactive] public bool DisableDynamicSampleRate { get; set; } = false;
-
-		[Reactive][MinMax(0, 100)] public UInt32 MasterVolume { get; set; } = 100;
-		[Reactive] public AudioSampleRate SampleRate { get; set; } = AudioSampleRate._48000;
-		[Reactive][MinMax(15, 300)] public UInt32 AudioLatency { get; set; } = 60;
-
-		[Reactive] public bool MuteSoundInBackground { get; set; } = false;
-		[Reactive] public bool ReduceSoundInBackground { get; set; } = true;
-		[Reactive] public bool ReduceSoundInFastForward { get; set; } = false;
-		[Reactive][MinMax(0, 100)] public int VolumeReduction { get; set; } = 75;
-
-		[Reactive] public bool ReverbEnabled { get; set; } = false;
-		[Reactive][MinMax(1, 10)] public UInt32 ReverbStrength { get; set; } = 5;
-		[Reactive][MinMax(1, 30)] public UInt32 ReverbDelay { get; set; } = 10;
-
-		[Reactive] public bool CrossFeedEnabled { get; set; } = false;
-		[Reactive][MinMax(0, 100)] public UInt32 CrossFeedRatio { get; set; } = 0;
-
-		[Reactive] public bool EnableEqualizer { get; set; } = false;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band1Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band2Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band3Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band4Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band5Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band6Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band7Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band8Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band9Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band10Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band11Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band12Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band13Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band14Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band15Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band16Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band17Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band18Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band19Gain { get; set; } = 0;
-		[Reactive][MinMax(-20.0, 20.0)] public double Band20Gain { get; set; } = 0;
-
-		[Reactive] public bool AudioPlayerEnableTrackLength { get; set; } = true;
-		[Reactive][MinMax(0, 9999)] public UInt32 AudioPlayerTrackLength { get; set; } = 120;
-		[Reactive] public bool AudioPlayerAutoDetectSilence { get; set; } = true;
-		[Reactive][MinMax(0, 999999)] public UInt32 AudioPlayerSilenceDelay { get; set; } = 3;
+		[ObservableProperty] public partial string AudioDevice { get; set; } = "";
+		[ObservableProperty] public partial bool EnableAudio { get; set; } = true;
+		[ObservableProperty] public partial bool DisableDynamicSampleRate { get; set; } = false;
+
+		[ObservableProperty][MinMax(0, 100)] public partial UInt32 MasterVolume { get; set; } = 100;
+		[ObservableProperty] public partial AudioSampleRate SampleRate { get; set; } = AudioSampleRate._48000;
+		[ObservableProperty][MinMax(15, 300)] public partial UInt32 AudioLatency { get; set; } = 60;
+
+		[ObservableProperty] public partial bool MuteSoundInBackground { get; set; } = false;
+		[ObservableProperty] public partial bool ReduceSoundInBackground { get; set; } = true;
+		[ObservableProperty] public partial bool ReduceSoundInFastForward { get; set; } = false;
+		[ObservableProperty][MinMax(0, 100)] public partial int VolumeReduction { get; set; } = 75;
+
+		[ObservableProperty] public partial bool ReverbEnabled { get; set; } = false;
+		[ObservableProperty][MinMax(1, 10)] public partial UInt32 ReverbStrength { get; set; } = 5;
+		[ObservableProperty][MinMax(1, 30)] public partial UInt32 ReverbDelay { get; set; } = 10;
+
+		[ObservableProperty] public partial bool CrossFeedEnabled { get; set; } = false;
+		[ObservableProperty][MinMax(0, 100)] public partial UInt32 CrossFeedRatio { get; set; } = 0;
+
+		[ObservableProperty] public partial bool EnableEqualizer { get; set; } = false;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band1Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band2Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band3Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band4Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band5Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band6Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band7Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band8Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band9Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band10Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band11Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band12Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band13Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band14Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band15Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band16Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band17Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band18Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band19Gain { get; set; } = 0;
+		[ObservableProperty][MinMax(-20.0, 20.0)] public partial double Band20Gain { get; set; } = 0;
+
+		[ObservableProperty] public partial bool AudioPlayerEnableTrackLength { get; set; } = true;
+		[ObservableProperty][MinMax(0, 9999)] public partial UInt32 AudioPlayerTrackLength { get; set; } = 120;
+		[ObservableProperty] public partial bool AudioPlayerAutoDetectSilence { get; set; } = true;
+		[ObservableProperty][MinMax(0, 999999)] public partial UInt32 AudioPlayerSilenceDelay { get; set; } = 3;
 
 		public void ApplyConfig()
 		{

UI/Config/AudioPlayerConfig.cs

@@ -1,6 +1,5 @@
-using Mesen.Interop;
-using ReactiveUI;
-using ReactiveUI.Fody.Helpers;
+using CommunityToolkit.Mvvm.ComponentModel;
+using Mesen.Interop;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -10,11 +9,11 @@
 
 namespace Mesen.Config
 {
-	public class AudioPlayerConfig : BaseConfig<AudioPlayerConfig>
+	public partial class AudioPlayerConfig : BaseConfig<AudioPlayerConfig>
 	{
-		[Reactive] public UInt32 Volume { get; set; } = 100;
-		[Reactive] public bool Repeat { get; set; } = false;
-		[Reactive] public bool Shuffle { get; set; } = false;
+		[ObservableProperty] public partial UInt32 Volume { get; set; } = 100;
+		[ObservableProperty] public partial bool Repeat { get; set; } = false;
+		[ObservableProperty] public partial bool Shuffle { get; set; } = false;
 
 		public void ApplyConfig()
 		{

UI/Config/BaseConfig.cs

@@ -1,11 +1,11 @@
-using Mesen.Utilities;
-using ReactiveUI;
+using CommunityToolkit.Mvvm.ComponentModel;
+using Mesen.Utilities;
 using System;
 using System.Text.Json;
 
 namespace Mesen.Config
 {
-	public class BaseConfig<T> : ReactiveObject where T : class
+	public partial class BaseConfig<T> : ObservableObject where T : class
 	{
 		public T Clone()
 		{

UI/Config/BaseWindowConfig.cs

@@ -5,7 +5,7 @@
 
 namespace Mesen.Config
 {
-	public class BaseWindowConfig<T> : BaseConfig<T> where T : class
+	public partial class BaseWindowConfig<T> : BaseConfig<T> where T : class
 	{
 		public MesenSize WindowSize { get; set; } = new PixelSize(0, 0);
 		public MesenPoint WindowLocation { get; set; } = new PixelPoint(0, 0);
@@ -30,7 +30,7 @@ public void SaveWindowSettings(Window wnd)
 		public void LoadWindowSettings(Window wnd)
 		{
 			//Update _restoreBounds when size/position changes
-			wnd.GetPropertyChangedObservable(Window.ClientSizeProperty).Subscribe(x => UpdateRestoreBounds(wnd));
+			wnd.SizeChanged += (s, e) => UpdateRestoreBounds(wnd);
 			wnd.PositionChanged += (s, e) => UpdateRestoreBounds(wnd);
 
 			if(WindowSize.Width != 0 && WindowSize.Height != 0) {

UI/Config/CheatCodes.cs

@@ -1,7 +1,7 @@
 using Mesen.Interop;
 using Mesen.Utilities;
 using Mesen.ViewModels;
-using ReactiveUI.Fody.Helpers;
+using CommunityToolkit.Mvvm.ComponentModel;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -70,12 +70,12 @@ public static void ApplyCheats(IEnumerable<CheatCode> cheats)
 		}
 	}
 
-	public class CheatCode : ViewModelBase
+	public partial class CheatCode : ViewModelBase
 	{
-		[Reactive] public string Description { get; set; } = "";
-		[Reactive] public CheatType Type { get; set; }
-		[Reactive] public bool Enabled { get; set; } = true;
-		[Reactive] public string Codes { get; set; } = "";
+		[ObservableProperty] public partial string Description { get; set; } = "";
+		[ObservableProperty] public partial CheatType Type { get; set; }
+		[ObservableProperty] public partial bool Enabled { get; set; } = true;
+		[ObservableProperty] public partial string Codes { get; set; } = "";
 
 		public List<InteropCheatCode> ToInteropCheats()
 		{

UI/Config/CheatWindowConfig.cs

@@ -1,5 +1,5 @@
 using Avalonia;
-using ReactiveUI.Fody.Helpers;
+using CommunityToolkit.Mvvm.ComponentModel;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -8,7 +8,7 @@
 
 namespace Mesen.Config
 {
-	public class CheatWindowConfig : BaseWindowConfig<CheatWindowConfig>
+	public partial class CheatWindowConfig : BaseWindowConfig<CheatWindowConfig>
 	{
 		public bool DisableAllCheats { get; set; } = false;
 		public List<int> ColumnWidths { get; set; } = new();

UI/Config/ConfigManager.cs

@@ -159,7 +159,9 @@ public static bool ProcessSwitch(string switchArg)
 				object? cfg = ConfigManager.Config;
 				PropertyInfo? property;
 				for(int i = 0; i < switchPath.Length; i++) {
+#pragma warning disable IL2075 // 'this' argument does not satisfy 'DynamicallyAccessedMembersAttribute' in call to target method. The return value of the source method does not have matching annotations.
 					property = cfg.GetType().GetProperty(switchPath[i], BindingFlags.Public | BindingFlags.Instance | BindingFlags.IgnoreCase);
+#pragma warning restore IL2075 // 'this' argument does not satisfy 'DynamicallyAccessedMembersAttribute' in call to target method. The return value of the source method does not have matching annotations.
 					if(property == null) {
 						//Invalid switch name
 						return false;