allow user to change the state history settings for the currently open TAS project

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

@@ -60,7 +60,7 @@ namespace BizHawk.Client.Common
 		/// <summary>
 		/// Updates the internal state saving logic settings
 		/// </summary>
-		void UpdateSettings(ZwinderStateManagerSettings settings);
+		void UpdateSettings(ZwinderStateManagerSettings settings, bool keepOldStates = false);
 
 		/// <summary>
 		/// Serializes the current state of the instance for persisting to disk

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

@@ -25,33 +25,12 @@ namespace BizHawk.Client.Common
 
 		// When recent states are evicted this interval is used to determine if we need to reserve the state
 		// We always want to keep some states throughout the movie
-		private readonly int _ancientInterval;
+		private int _ancientInterval;
 
 		internal ZwinderStateManager(ZwinderStateManagerSettings settings, Func<int, bool> reserveCallback)
 		{
-			Settings = settings;
+			UpdateSettings(settings, false);
 
-			_current = new ZwinderBuffer(new RewindConfig
-			{
-				UseCompression = settings.CurrentUseCompression,
-				BufferSize = settings.CurrentBufferSize,
-				TargetFrameLength = settings.CurrentTargetFrameLength
-			});
-			_recent = new ZwinderBuffer(new RewindConfig
-			{
-				UseCompression = settings.RecentUseCompression,
-				BufferSize = settings.RecentBufferSize,
-				TargetFrameLength = settings.RecentTargetFrameLength
-			});
-
-			_gapFiller = new ZwinderBuffer(new RewindConfig
-			{
-				UseCompression = settings.GapsUseCompression,
-				BufferSize = settings.GapsBufferSize,
-				TargetFrameLength = settings.GapsTargetFrameLength
-			});
-
-			_ancientInterval = settings.AncientStateInterval;
 			_reserveCallback = reserveCallback;
 		}
 
@@ -95,8 +74,83 @@ namespace BizHawk.Client.Common
 			}
 		}
 
-		// TODO: private set, refactor LoadTasprojExtras to hold onto a settings object and pass it in to Create() method
-		public ZwinderStateManagerSettings Settings { get; set; }
+		public ZwinderStateManagerSettings Settings { get; private set; }
+
+		public void UpdateSettings(ZwinderStateManagerSettings settings, bool keepOldStates = false)
+		{
+			Settings = settings;
+
+			_current = UpdateBuffer(_current, settings.Current(), keepOldStates);
+			_recent = UpdateBuffer(_recent, settings.Recent(), keepOldStates);
+			_gapFiller = UpdateBuffer(_gapFiller, settings.GapFiller(), keepOldStates);
+
+			if (keepOldStates)
+			{
+				// For ancients ... lets just make sure we aren't keeping states with a gap below the new interval
+				if (settings.AncientStateInterval > _ancientInterval)
+				{
+					int lastReserved = 0;
+					List<int> framesToRemove = new List<int>();
+					foreach (int f in _reserved.Keys)
+					{
+						if (!_reserveCallback(f) && f - lastReserved < settings.AncientStateInterval)
+							framesToRemove.Add(f);
+						else
+							lastReserved = f;
+					}
+					foreach (int f in framesToRemove)
+						EvictReserved(f);
+				}
+			}
+			else
+			{
+				foreach (int f in _reserved.Keys)
+				{
+					if (f != 0 && !_reserveCallback(f))
+						EvictReserved(f);
+				}
+			}
+
+			_ancientInterval = settings.AncientStateInterval;
+			RebuildStateCache();
+		}
+		private ZwinderBuffer UpdateBuffer(ZwinderBuffer buffer, RewindConfig newConfig, bool keepOldStates)
+		{
+			if (buffer == null) // just make a new one, plain and simple
+				buffer = new ZwinderBuffer(newConfig);
+			else if (!buffer.MatchesSettings(newConfig)) // no need to do anything if these settings are already in use
+			{
+				if (keepOldStates)
+				{
+					// force capture all the old states, let the buffer handle decay if they don't all fit
+					ZwinderBuffer old = buffer;
+					buffer = new ZwinderBuffer(newConfig);
+					for (int i = 0; i < old.Count; i++)
+					{
+						ZwinderBuffer.StateInformation si = old.GetState(i);
+						// don't allow states that should be reserved to decay here, where we don't attempt re-capture
+						if (_reserveCallback(si.Frame))
+							AddToReserved(si);
+						else
+							buffer.Capture(si.Frame, s => si.GetReadStream().CopyTo(s), null, true);
+					}
+					old.Dispose();
+				}
+				else
+				{
+					buffer.Dispose();
+					buffer = new ZwinderBuffer(newConfig);
+				}
+			}
+			return buffer;
+		}
+
+		private void RebuildStateCache()
+		{
+			StateCache.Clear();
+			foreach (StateInfo state in AllStates())
+				StateCache.Add(state.Frame);
+		}
 
 		public int Count => _current.Count + _recent.Count + _gapFiller.Count + _reserved.Count;
 
@@ -383,8 +437,6 @@ namespace BizHawk.Client.Common
 			return _reserved.Count < origCount;
 		}
 
-		public void UpdateSettings(ZwinderStateManagerSettings settings) => Settings = settings;
-
 		public bool InvalidateAfter(int frame)
 		{
 			if (frame < 0)
@@ -418,11 +470,7 @@ namespace BizHawk.Client.Common
 				ret._reserved.Add(key, data);
 			}
 
-			var allStates = ret.AllStates().ToList();
-			foreach (var state in allStates)
-			{
-				ret.StateCache.Add(state.Frame);
-			}
+			ret.RebuildStateCache();
 
 			return ret;
 		}

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

@@ -68,5 +68,34 @@ namespace BizHawk.Client.Common
 		[DisplayName("Ancient State Interval")]
 		[Description("How often to maintain states when outside of Current and Recent intervals")]
 		public int AncientStateInterval { get; set; } = 5000;
+
+		// Just to simplify some other code.
+		public RewindConfig Current()
+		{
+			return new RewindConfig()
+			{
+				UseCompression = CurrentUseCompression,
+				BufferSize = CurrentBufferSize,
+				TargetFrameLength = CurrentTargetFrameLength
+			};
+		}
+		public RewindConfig Recent()
+		{
+			return new RewindConfig()
+			{
+				UseCompression = RecentUseCompression,
+				BufferSize = RecentBufferSize,
+				TargetFrameLength = RecentTargetFrameLength
+			};
+		}
+		public RewindConfig GapFiller()
+		{
+			return new RewindConfig()
+			{
+				UseCompression = GapsUseCompression,
+				BufferSize = GapsBufferSize,
+				TargetFrameLength = GapsTargetFrameLength
+			};
+		}
 	}
 }

src/BizHawk.Client.Common/rewind/ZwinderBuffer.cs

@@ -106,6 +106,14 @@ namespace BizHawk.Client.Common
 			return Math.Max(idealInterval, 1);
 		}
 
+		public bool MatchesSettings(RewindConfig settings)
+		{
+			long size = 1L << (int)Math.Floor(Math.Log(settings.BufferSize, 2));
+			return Size == size &&
+				_useCompression == settings.UseCompression &&
+				_targetFrameLength == settings.TargetFrameLength;
+		}
+
 		private bool ShouldCapture(int frame)
 		{
 			if (Count == 0)

src/BizHawk.Client.EmuHawk/tools/TAStudio/TAStudio.MenuItems.cs

@@ -996,17 +996,11 @@ namespace BizHawk.Client.EmuHawk
 			}.Show();
 		}
 
-		private void UpdateStateSettings(ZwinderStateManagerSettings settings)
-		{
-			Config.Movies.DefaultTasStateManagerSettings = settings;
-			CurrentTasMovie.TasStateManager.UpdateSettings(settings);
-		}
-
 		private void StateHistorySettingsMenuItem_Click(object sender, EventArgs e)
 		{
 			new DefaultGreenzoneSettings(
-				new ZwinderStateManagerSettings(Config.Movies.DefaultTasStateManagerSettings),
-				UpdateStateSettings)
+				new ZwinderStateManagerSettings(CurrentTasMovie.TasStateManager.Settings),
+				s => { CurrentTasMovie.TasStateManager.UpdateSettings(s, true); })
 			{
 				Location = this.ChildPointToScreen(TasView),
 				Text = "Savestate History Settings",