From 0bfe3cb6ab2734683fde7baa3c4e39a7588ba43b Mon Sep 17 00:00:00 2001
From: YoshiRulz <OSSYoshiRulz@gmail.com>
Date: Thu, 8 Apr 2021 16:37:20 +1000
Subject: [PATCH] Genericise SwappableDisplaySurfaceSet

---
 .../SwappableDisplaySurfaceSet.cs             | 24 ++++++++++++-------
 .../DisplayManager/DisplayManager.cs          | 12 ++++++----
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/src/BizHawk.Client.Common/DisplayManager/SwappableDisplaySurfaceSet.cs b/src/BizHawk.Client.Common/DisplayManager/SwappableDisplaySurfaceSet.cs
index c58c93fa8b..515c3f885f 100644
--- a/src/BizHawk.Client.Common/DisplayManager/SwappableDisplaySurfaceSet.cs
+++ b/src/BizHawk.Client.Common/DisplayManager/SwappableDisplaySurfaceSet.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 
 namespace BizHawk.Client.Common
@@ -6,20 +7,25 @@ namespace BizHawk.Client.Common
 	/// encapsulates thread-safe concept of pending/current display surfaces, reusing buffers where matching 
 	/// sizes are available and keeping them cleaned up when they don't seem like they'll need to be used anymore
 	/// </summary>
-	public class SwappableDisplaySurfaceSet
+	public class SwappableDisplaySurfaceSet<T>
+		where T : class, IDisplaySurface
 	{
-		private DisplaySurface _pending, _current;
+		private readonly Func<int, int, T> _createDispSurface;
+
+		private T _pending, _current;
 		private bool _isPending;
-		private readonly Queue<DisplaySurface> _releasedSurfaces = new Queue<DisplaySurface>();
+		private readonly Queue<T> _releasedSurfaces = new();
+
+		public SwappableDisplaySurfaceSet(Func<int, int, T> createDispSurface) => _createDispSurface = createDispSurface;
 
 		/// <summary>
 		/// retrieves a surface with the specified size, reusing an old buffer if available and clearing if requested
 		/// </summary>
-		public DisplaySurface AllocateSurface(int width, int height, bool needsClear = true)
+		public T AllocateSurface(int width, int height, bool needsClear = true)
 		{
 			for (; ; )
 			{
-				DisplaySurface trial;
+				T trial;
 				lock (this)
 				{
 					if (_releasedSurfaces.Count == 0) break;
@@ -38,13 +44,13 @@ namespace BizHawk.Client.Common
 				trial.Dispose();
 			}
 
-			return new DisplaySurface(width, height);
+			return _createDispSurface(width, height);
 		}
 
 		/// <summary>
 		/// sets the provided buffer as pending. takes control of the supplied buffer
 		/// </summary>
-		public void SetPending(DisplaySurface newPending)
+		public void SetPending(T newPending)
 		{
 			lock (this)
 			{
@@ -54,7 +60,7 @@ namespace BizHawk.Client.Common
 			}
 		}
 
-		public void ReleaseSurface(DisplaySurface surface)
+		public void ReleaseSurface(T surface)
 		{
 			lock (this) _releasedSurfaces.Enqueue(surface);
 		}
@@ -62,7 +68,7 @@ namespace BizHawk.Client.Common
 		/// <summary>
 		/// returns the current buffer, making the most recent pending buffer (if there is such) as the new current first.
 		/// </summary>
-		public DisplaySurface GetCurrent()
+		public T GetCurrent()
 		{
 			lock (this)
 			{
diff --git a/src/BizHawk.Client.EmuHawk/DisplayManager/DisplayManager.cs b/src/BizHawk.Client.EmuHawk/DisplayManager/DisplayManager.cs
index ec27a6451b..0a430e8c3e 100644
--- a/src/BizHawk.Client.EmuHawk/DisplayManager/DisplayManager.cs
+++ b/src/BizHawk.Client.EmuHawk/DisplayManager/DisplayManager.cs
@@ -31,6 +31,8 @@ namespace BizHawk.Client.EmuHawk
 	/// </summary>
 	public class DisplayManager : IDisplayManagerForApi, IWindowCoordsTransformer, IDisposable
 	{
+		private static DisplaySurface CreateDisplaySurface(int w, int h) => new(w, h);
+
 		private class DisplayManagerRenderTargetProvider : IRenderTargetProvider
 		{
 			private readonly Func<Size, RenderTarget> _callback;
@@ -129,8 +131,8 @@ namespace BizHawk.Client.EmuHawk
 				}
 			}
 
-			_apiHawkSurfaceSets[DisplaySurfaceID.EmuCore] = new SwappableDisplaySurfaceSet();
-			_apiHawkSurfaceSets[DisplaySurfaceID.Client] = new SwappableDisplaySurfaceSet();
+			_apiHawkSurfaceSets[DisplaySurfaceID.EmuCore] = new(CreateDisplaySurface);
+			_apiHawkSurfaceSets[DisplaySurfaceID.Client] = new(CreateDisplaySurface);
 			_apiHawkSurfaceFrugalizers[DisplaySurfaceID.EmuCore] = new TextureFrugalizer(_gl);
 			_apiHawkSurfaceFrugalizers[DisplaySurfaceID.Client] = new TextureFrugalizer(_gl);
 
@@ -1102,7 +1104,7 @@ namespace BizHawk.Client.EmuHawk
 		/// <remarks>Can't this just be a prop of <see cref="IDisplaySurface"/>? --yoshi</remarks>
 		private readonly Dictionary<IDisplaySurface, DisplaySurfaceID> _apiHawkSurfaceToID = new();
 
-		private readonly Dictionary<DisplaySurfaceID, SwappableDisplaySurfaceSet> _apiHawkSurfaceSets = new();
+		private readonly Dictionary<DisplaySurfaceID, SwappableDisplaySurfaceSet<DisplaySurface>> _apiHawkSurfaceSets = new();
 
 		/// <summary>
 		/// Peeks a locked lua surface, or returns null if it isn't locked
@@ -1123,7 +1125,7 @@ namespace BizHawk.Client.EmuHawk
 
 			if (!_apiHawkSurfaceSets.TryGetValue(surfaceID, out var sdss))
 			{
-				sdss = new SwappableDisplaySurfaceSet();
+				sdss = new(CreateDisplaySurface);
 				_apiHawkSurfaceSets.Add(surfaceID, sdss);
 			}
 
@@ -1171,7 +1173,7 @@ namespace BizHawk.Client.EmuHawk
 		/// <exception cref="InvalidOperationException">already unlocked</exception>
 		public void UnlockApiHawkSurface(IDisplaySurface surface)
 		{
-			if (surface is not DisplaySurface dispSurfaceImpl) throw new ArgumentException("o noes", nameof(surface));
+			if (surface is not DisplaySurface dispSurfaceImpl) throw new ArgumentException("don't mix " + nameof(IDisplaySurface) + " implementations!", nameof(surface));
 			if (!_apiHawkSurfaceToID.ContainsKey(dispSurfaceImpl))
 			{
 				throw new InvalidOperationException("Surface was not locked as a lua surface");