Add a level of indirection to DirectX/XAudio2 ctors and static calls

src/BizHawk.Bizware.DirectX/IndirectX.cs

@@ -0,0 +1,29 @@
+#nullable enable
+
+using System;
+using System.Collections.Generic;
+
+using BizHawk.Bizware.BizwareGL;
+using BizHawk.Client.Common;
+
+namespace BizHawk.Bizware.DirectX
+{
+	/// <summary>An indirection, so that types from the SlimDX assembly don't need to be resolved if DirectX/XAudio2 features are never used.</summary>
+	public static class IndirectX
+	{
+		public static IGL CreateD3DGLImpl()
+			=> new IGL_SlimDX9();
+
+		public static ISoundOutput CreateDSSoundOutput(IHostAudioManager sound, IntPtr mainWindowHandle, string chosenDeviceName)
+			=> new DirectSoundSoundOutput(sound, mainWindowHandle, chosenDeviceName);
+
+		public static ISoundOutput CreateXAudio2SoundOutput(IHostAudioManager sound, string chosenDeviceName)
+			=> new XAudio2SoundOutput(sound, chosenDeviceName);
+
+		public static IEnumerable<string> GetDSSinkNames()
+			=> DirectSoundSoundOutput.GetDeviceNames();
+
+		public static IEnumerable<string> GetXAudio2SinkNames()
+			=> XAudio2SoundOutput.GetDeviceNames();
+	}
+}

src/BizHawk.Client.EmuHawk/MainForm.Events.cs

@@ -900,8 +900,8 @@ namespace BizHawk.Client.EmuHawk
 		{
 			static IEnumerable<string> GetDeviceNamesCallback(ESoundOutputMethod outputMethod) => outputMethod switch
 			{
-				ESoundOutputMethod.DirectSound => DirectSoundSoundOutput.GetDeviceNames(),
-				ESoundOutputMethod.XAudio2 => XAudio2SoundOutput.GetDeviceNames(),
+				ESoundOutputMethod.DirectSound => IndirectX.GetDSSinkNames(),
+				ESoundOutputMethod.XAudio2 => IndirectX.GetXAudio2SinkNames(),
 				ESoundOutputMethod.OpenAL => OpenALSoundOutput.GetDeviceNames(),
 				_ => Enumerable.Empty<string>()
 			};

src/BizHawk.Client.EmuHawk/Program.cs

@@ -181,17 +181,15 @@ namespace BizHawk.Client.EmuHawk
 							// possibly sharing config w/ Windows, assume the user wants the not-slow method (but don't change the config)
 							return TryInitIGL(EDispMethod.OpenGL);
 						}
-						IGL_SlimDX9 glSlimDX;
 						try
 						{
-							glSlimDX = new IGL_SlimDX9();
+							return CheckRenderer(IndirectX.CreateD3DGLImpl());
 						}
 						catch (Exception ex)
 						{
 							new ExceptionBox(new Exception("Initialization of Direct3d 9 Display Method failed; falling back to GDI+", ex)).ShowDialog();
 							return TryInitIGL(initialConfig.DispMethod = EDispMethod.GdiPlus);
 						}
-						return CheckRenderer(glSlimDX);
 					case EDispMethod.OpenGL:
 						var glOpenTK = new IGL_TK(2, 0, false);
 						if (glOpenTK.Version < 200)

src/BizHawk.Client.EmuHawk/Sound/Sound.cs

@@ -51,8 +51,8 @@ namespace BizHawk.Client.EmuHawk
 			{
 				_outputDevice = config.SoundOutputMethod switch
 				{
-					ESoundOutputMethod.DirectSound => new DirectSoundSoundOutput(this, mainWindowHandle, config.SoundDevice),
-					ESoundOutputMethod.XAudio2 => new XAudio2SoundOutput(this, config.SoundDevice),
+					ESoundOutputMethod.DirectSound => IndirectX.CreateDSSoundOutput(this, mainWindowHandle, config.SoundDevice),
+					ESoundOutputMethod.XAudio2 => IndirectX.CreateXAudio2SoundOutput(this, config.SoundDevice),
 					ESoundOutputMethod.OpenAL => new OpenALSoundOutput(this, config.SoundDevice),
 					_ => new DummySoundOutput(this)
 				};