Tweaks for map generator performance.

The map generator is already performant, but we can remove a few rough edges from infrastructure it interacts with.

- Add TypeDictionary constructor to clone from an existing copy. The map editor infrastructure relies heavily on cloning ActorReferences and the underlying dictionaries. A dedicated clone method avoids reflection overhead for CreateTypeContainer on a fresh instance.
- Use ThrowIndexOutOfRangeException helper. This allows the Index method to be inlined.
- Reuse lists in FloodFill. This avoids allocating and resizing new lists on each loop when we can reuse the existing capacity.
- Manage CellEntryChanged at the layer rather than individual previews. We only need to attach/detach from the delegate once at the layer, rather than many times as previews are added and removed.

OpenRA.Game/Map/ActorReference.cs

@@ -54,13 +54,8 @@ namespace OpenRA
 		public ActorReference(string type, TypeDictionary inits)
 		{
 			Type = type;
-			initDict = new Lazy<TypeDictionary>(() =>
+			var initsClone = new TypeDictionary(inits);
-			{
+			initDict = Exts.Lazy(() => initsClone);
-				var dict = new TypeDictionary();
-				foreach (var i in inits)
-					dict.Add(i);
-				return dict;
-			});
 		}
 
 		static ActorInit LoadInit(string initName, MiniYaml initYaml)
@@ -110,11 +105,7 @@ namespace OpenRA
 
 		public ActorReference Clone()
 		{
-			var clone = new ActorReference(Type);
+			return new ActorReference(Type, initDict.Value);
-			foreach (var init in initDict.Value)
-				clone.initDict.Value.Add(init);
-
-			return clone;
 		}
 
 		public void Add(ActorInit init)

OpenRA.Game/Primitives/TypeDictionary.cs

@@ -12,6 +12,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace OpenRA.Primitives
 {
@@ -20,7 +21,17 @@ namespace OpenRA.Primitives
 		static readonly Func<Type, ITypeContainer> CreateTypeContainer = t =>
 			(ITypeContainer)typeof(TypeContainer<>).MakeGenericType(t).GetConstructor(Type.EmptyTypes).Invoke(null);
 
-		readonly Dictionary<Type, ITypeContainer> data = [];
+		readonly Dictionary<Type, ITypeContainer> data;
+
+		public TypeDictionary()
+		{
+			data = [];
+		}
+
+		public TypeDictionary(TypeDictionary cloneFrom)
+		{
+			data = cloneFrom.data.ToDictionary(kvp => kvp.Key, kvp => kvp.Value.Clone());
+		}
 
 		ITypeContainer InnerGet(Type t)
 		{
@@ -127,11 +138,12 @@ namespace OpenRA.Primitives
 			void Add(object value);
 			void Remove(object value);
 			void TrimExcess();
+			ITypeContainer Clone();
 		}
 
 		sealed class TypeContainer<T> : ITypeContainer
 		{
-			public List<T> Objects { get; } = [];
+			public List<T> Objects { get; private init; } = [];
 
 			public int Count => Objects.Count;
 
@@ -149,6 +161,11 @@ namespace OpenRA.Primitives
 			{
 				Objects.TrimExcess();
 			}
+
+			public ITypeContainer Clone()
+			{
+				return new TypeContainer<T>() { Objects = Objects.ToList() };
+			}
 		}
 	}
 

OpenRA.Mods.Common/MapGenerator/CellLayerUtils.cs

@@ -561,11 +561,12 @@ namespace OpenRA.Mods.Common.MapGenerator
 			Func<CPos, P, P?> filler,
 			ImmutableArray<CVec> spread) where P : struct
 		{
+			var current = new List<(CPos CPos, P Prop)>();
 			var next = seeds.ToList();
 			while (next.Count != 0)
 			{
-				var current = next;
+				(next, current) = (current, next);
-				next = [];
+				next.Clear();
 				foreach (var (source, prop) in current)
 				{
 					var newProp = filler(source, prop);

OpenRA.Mods.Common/MapGenerator/Matrix.cs

@@ -57,11 +57,16 @@ namespace OpenRA.Mods.Common.MapGenerator
 		public int Index(int x, int y)
 		{
 			if (!ContainsXY(x, y))
-				throw new IndexOutOfRangeException(
+				ThrowIndexOutOfRangeException(x, y);
-					$"({x}, {y}) is out of bounds for a matrix of size ({Size.X}, {Size.Y})");
 			return y * Size.X + x;
 		}
 
+		void ThrowIndexOutOfRangeException(int x, int y)
+		{
+			throw new IndexOutOfRangeException(
+				$"({x}, {y}) is out of bounds for a matrix of size ({Size.X}, {Size.Y})");
+		}
+
 		/// <summary>
 		/// Convert a Data index into a pair of coordinates.
 		/// </summary>

OpenRA.Mods.Common/MapGenerator/MatrixUtils.cs

@@ -345,11 +345,12 @@ namespace OpenRA.Mods.Common.MapGenerator
 			Func<int2, P, P?> filler,
 			ImmutableArray<int2> spread) where P : struct
 		{
+			var current = new List<(int2 XY, P Prop)>();
 			var next = seeds.ToList();
 			while (next.Count != 0)
 			{
-				var current = next;
+				(next, current) = (current, next);
-				next = [];
+				next.Clear();
 				foreach (var (source, prop) in current)
 				{
 					var newProp = filler(source, prop);

OpenRA.Mods.Common/Traits/Production.cs

@@ -54,9 +54,7 @@ namespace OpenRA.Mods.Common.Traits
 			var exitLocations = new List<CPos>();
 
 			// Clone the initializer dictionary for the new actor
-			var td = new TypeDictionary();
+			var td = new TypeDictionary(inits);
-			foreach (var init in inits)
-				td.Add(init);
 
 			if (exitinfo != null && self.OccupiesSpace != null && producee.HasTraitInfo<IOccupySpaceInfo>())
 			{

OpenRA.Mods.Common/Traits/ProductionFromMapEdge.cs

@@ -82,13 +82,12 @@ namespace OpenRA.Mods.Common.Traits
 
 			self.World.AddFrameEndTask(w =>
 			{
-				var td = new TypeDictionary();
+				var td = new TypeDictionary(inits)
-				foreach (var init in inits)
+				{
-					td.Add(init);
+					new LocationInit(location.Value),
-
+					new CenterPositionInit(pos),
-				td.Add(new LocationInit(location.Value));
+					new FacingInit(initialFacing)
-				td.Add(new CenterPositionInit(pos));
+				};
-				td.Add(new FacingInit(initialFacing));
 
 				var newUnit = self.World.CreateActor(producee.Name, td);
 

OpenRA.Mods.Common/Traits/ProductionParadrop.cs

@@ -122,9 +122,7 @@ namespace OpenRA.Mods.Common.Traits
 			var altitude = self.World.Map.Rules.Actors[actorType].TraitInfo<AircraftInfo>().CruiseAltitude;
 
 			// Clone the initializer dictionary for the new actor
-			var td = new TypeDictionary();
+			var td = new TypeDictionary(inits);
-			foreach (var init in inits)
-				td.Add(init);
 
 			if (self.OccupiesSpace != null)
 			{

OpenRA.Mods.Common/Traits/World/EditorActorLayer.cs

@@ -42,7 +42,7 @@ namespace OpenRA.Mods.Common.Traits
 		public override object Create(ActorInitializer init) { return new EditorActorLayer(this); }
 	}
 
-	public class EditorActorLayer : IWorldLoaded, ITickRender, IRender, IRadarSignature, ICreatePlayers, IRenderAnnotations
+	public class EditorActorLayer : IWorldLoaded, ITickRender, IRender, IRadarSignature, ICreatePlayers, IRenderAnnotations, INotifyActorDisposing
 	{
 		const string ActorPrefix = "Actor";
 		const string PlayerSpawnName = "mpspawn";
@@ -101,6 +101,9 @@ namespace OpenRA.Mods.Common.Traits
 			}
 
 			AddRange(CollectionsMarshal.AsSpan(references), names);
+
+			world.Map.Height.CellEntryChanged += UpdatePreviewsOnMapChange;
+			world.Map.Ramp.CellEntryChanged += UpdatePreviewsOnMapChange;
 		}
 
 		void ITickRender.TickRender(WorldRenderer wr, Actor self)
@@ -400,7 +403,7 @@ namespace OpenRA.Mods.Common.Traits
 		public IEnumerable<EditorActorPreview> PreviewsAtCell(CPos cell)
 		{
 			return cellMap.At(new int2(cell.X - cellOffset.X, cell.Y - cellOffset.Y))
-				.Where(p => OccupiedCells(p).Any(fp => fp == cell));
+				.Where(p => OccupiedCells(p).Contains(cell));
 		}
 
 		public SubCell FreeSubCellAt(CPos cell)
@@ -426,6 +429,12 @@ namespace OpenRA.Mods.Common.Traits
 			return screenMap.At(worldPx);
 		}
 
+		void UpdatePreviewsOnMapChange(CPos changedCell)
+		{
+			foreach (var preview in PreviewsAtCell(changedCell))
+				preview.UpdateFromCellChange();
+		}
+
 		public Action OnPlayerRemoved = () => { };
 
 		static bool TryGetActorId(string name, out uint id)
@@ -472,6 +481,12 @@ namespace OpenRA.Mods.Common.Traits
 					destinationBuffer.Add((cell, preview.RadarColor));
 		}
 
+		void INotifyActorDisposing.Disposing(Actor self)
+		{
+			self.World.Map.Height.CellEntryChanged -= UpdatePreviewsOnMapChange;
+			self.World.Map.Ramp.CellEntryChanged -= UpdatePreviewsOnMapChange;
+		}
+
 		public EditorActorPreview this[string id]
 		{
 			get { return previews.FirstOrDefault(p => p.ID.Equals(id, StringComparison.OrdinalIgnoreCase)); }

OpenRA.Mods.Common/Traits/World/EditorActorPreview.cs

@@ -46,7 +46,6 @@ namespace OpenRA.Mods.Common.Traits
 		readonly TooltipInfoBase tooltip;
 		readonly ActorReference reference;
 		readonly Dictionary<INotifyEditorPlacementInfo, object> editorData = [];
-		readonly Action<CPos> onCellEntryChanged;
 
 		SelectionBoxAnnotationRenderable selectionBox;
 		IActorPreview[] previews;
@@ -69,7 +68,7 @@ namespace OpenRA.Mods.Common.Traits
 				throw new InvalidDataException($"Actor {id} of unknown type {reference.Type.ToLowerInvariant()}");
 
 			GenerateFootprint();
-			UpdateFromCellChange(null);
+			UpdateFromCellChange();
 
 			tooltip = Info.TraitInfos<EditorOnlyTooltipInfo>().FirstOrDefault(info => info.EnabledByDefault) as TooltipInfoBase
 				?? Info.TraitInfos<TooltipInfo>().FirstOrDefault(info => info.EnabledByDefault);
@@ -78,8 +77,6 @@ namespace OpenRA.Mods.Common.Traits
 
 			terrainRadarColorInfo = Info.TraitInfoOrDefault<RadarColorFromTerrainInfo>();
 			UpdateRadarColor();
-
-			onCellEntryChanged = cell => UpdateFromCellChange(cell);
 		}
 
 		public EditorActorPreview WithId(string id)
@@ -87,11 +84,8 @@ namespace OpenRA.Mods.Common.Traits
 			return new EditorActorPreview(worldRenderer, id, reference.Clone(), Owner);
 		}
 
-		void UpdateFromCellChange(CPos? cellChanged)
+		public void UpdateFromCellChange()
 		{
-			if (cellChanged != null && !Footprint.ContainsKey(cellChanged.Value))
-				return;
-
 			CenterPosition = PreviewPosition(worldRenderer.World, reference);
 			GeneratePreviews();
 			GenerateBounds();
@@ -183,18 +177,12 @@ namespace OpenRA.Mods.Common.Traits
 		{
 			foreach (var notify in Info.TraitInfos<INotifyEditorPlacementInfo>())
 				editorData[notify] = notify.AddedToEditor(this, worldRenderer.World);
-
-			worldRenderer.World.Map.Height.CellEntryChanged += onCellEntryChanged;
-			worldRenderer.World.Map.Ramp.CellEntryChanged += onCellEntryChanged;
 		}
 
 		public void RemovedFromEditor()
 		{
 			foreach (var kv in editorData)
 				kv.Key.RemovedFromEditor(this, worldRenderer.World, kv.Value);
-
-			worldRenderer.World.Map.Height.CellEntryChanged -= onCellEntryChanged;
-			worldRenderer.World.Map.Ramp.CellEntryChanged -= onCellEntryChanged;
 		}
 
 		public void AddInit<T>(T init) where T : ActorInit