Feature: Option for TAStudio to only save states on marker frames.

src/BizHawk.Client.Common/movie/tasproj/ZwinderStateManager.cs

@@ -622,6 +622,25 @@ namespace BizHawk.Client.Common
 						toSave.Add(si);
 				}
 
+				bw.Write(toSave.Count);
+				for (int i = 0; i < toSave.Count; i++)
+				{
+					bw.Write(toSave[i].Frame);
+					bw.Write(toSave[i].Size);
+					toSave[i].Read().CopyTo(bw.BaseStream);
+				}
+			}
+			else if (Settings.StatesToSave == ZwinderStateManagerSettings.States.MarkersOnly)
+			{
+				// Some states that should be reserved via marker might be in a ring buffer but not yet in _reserved.
+				List<StateInfo> allStates = AllStates().ToList();
+				List<StateInfo> toSave = new();
+				for (int i = 0; i < allStates.Count; i++)
+				{
+					if (_reserveCallback(allStates[i].Frame))
+						toSave.Add(allStates[i]);
+				}
+
 				bw.Write(toSave.Count);
 				for (int i = 0; i < toSave.Count; i++)
 				{

src/BizHawk.Client.Common/movie/tasproj/ZwinderStateManagerSettings.cs

@@ -116,6 +116,8 @@ namespace BizHawk.Client.Common
 			All,
 			[Display(Name = "Reserved Only")]
 			ReservedOnly,
+			[Display(Name = "Markers Only")]
+			MarkersOnly,
 			None,
 		}
 

src/BizHawk.Tests/Client.Common/Movie/ZwinderStateManagerTests.cs

@@ -685,6 +685,33 @@ namespace BizHawk.Tests.Client.Common.Movie
 			}
 		}
 
+
+		[TestMethod]
+		public void TestKeepsMarkersOnSave()
+		{
+			const int markerFrame = 15;
+			IStatable ss = CreateStateSource();
+			ZwinderStateManager manager = new ZwinderStateManager(new(), f => f == markerFrame);
+			manager.Settings.StatesToSave = ZwinderStateManagerSettings.States.MarkersOnly;
+
+			var ms = new MemoryStream();
+			ss.SaveStateBinary(new BinaryWriter(ms));
+			manager.Engage(ms.ToArray());
+
+			// Simulate playing movie.
+			int endFrame = markerFrame;
+			for (int i = 0; i <= endFrame; i++)
+				manager.Capture(i, ss);
+			// Simulate save and load
+			MemoryStream stream = new();
+			manager.SaveStateHistory(new(stream));
+			stream.Seek(0, SeekOrigin.Begin);
+			ZwinderStateManager loadedManager = ZwinderStateManager.Create(new(stream), manager.Settings, (f) => false);
+			// ASSERT: The only state saved is the maker frame.
+			Assert.AreEqual(1, loadedManager.AllStates().Count(), "Expected only two states in saved tasproj.");
+			Assert.IsTrue(loadedManager.HasState(markerFrame));
+		}
+
 		private class StateSource : IStatable
 		{
 			public int Frame { get; set; }