Add customization for room colors on the debug map

Celeste.Mod.mm/Patches/LevelData.cs

@@ -4,6 +4,7 @@
 using System;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
+using Monocle;
 using MonoMod;
 using MonoMod.Cil;
 using MonoMod.InlineRT;
@@ -16,6 +17,10 @@ public class patch_LevelData : LevelData {
 
         public Vector2? DefaultSpawn;
 
+        // custom room color
+        // if null, `EditorColorIndex` will be used to determine the room color
+        public Color? CustomEditorColor;
+
         public patch_LevelData(BinaryPacker.Element data) : base(data) {
             // no-op. MonoMod ignores this - we only need this to make the compiler shut up.
         }
@@ -29,6 +34,9 @@ public patch_LevelData(BinaryPacker.Element data) : base(data) {
         [MonoModConstructor]
         public void ctor(BinaryPacker.Element data) {
             orig_ctor(data);
+
+            string color = data.Attr("color");
+            CustomEditorColor = string.IsNullOrEmpty(color) ? null : Calc.HexToColor(color);
         }
 
         private void CheckForDefaultSpawn(BinaryPacker.Element spawn, Vector2 coords) {

Celeste.Mod.mm/Patches/LevelTemplate.cs

@@ -1,4 +1,5 @@
 using Celeste.Mod.Helpers;
+using Microsoft.Xna.Framework;
 using Mono.Cecil;
 using Mono.Cecil.Cil;
 using Monocle;
@@ -10,26 +11,41 @@
 
 namespace Celeste.Editor {
     class patch_LevelTemplate : LevelTemplate {
+        // expose this private field to our patch
+        private static new Color[] fgTilesColor;
+
+        // custom room color
+        // if null, `EditorColorIndex` will be used to determine the room color
+        public Color? CustomEditorColor;
+        public Color EditorColor => CustomEditorColor ?? fgTilesColor[EditorColorIndex];
+
         public patch_LevelTemplate(LevelData data)
             : base(data) {
             // no-op. MonoMod ignores this - we only need this to make the compiler shut up.
         }
-
-        [MonoModConstructor]
+
         [MonoModIgnore] // we don't want to change anything in the method...
         [PatchTrackableStrawberryCheck] // except manipulating it with MonoModRules
-        public extern void ctor(LevelData data);
+        public extern void orig_ctor(LevelData data);
+
+        [MonoModConstructor]
+        public void ctor(LevelData data) {
+            orig_ctor(data);
 
-        [AddLevelTemplateCulling]
+            CustomEditorColor = ((patch_LevelData) data).CustomEditorColor;
+        }
+
         [MonoModIgnore]
-        public new extern void RenderContents(Camera camera, System.Collections.Generic.List<LevelTemplate> allLevels);
-
         [AddLevelTemplateCulling]
+        [PatchLevelTemplateRenderContents]
+        public new extern void RenderContents(Camera camera, System.Collections.Generic.List<LevelTemplate> allLevels);
+
         [MonoModIgnore]
-        public new extern void RenderOutline(Camera camera);
-
         [AddLevelTemplateCulling]
+        public new extern void RenderOutline(Camera camera);
+
         [MonoModIgnore]
+        [AddLevelTemplateCulling]
         public new extern void RenderHighlight(Camera camera, bool hovered, bool selected);
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -46,6 +62,12 @@ namespace MonoMod {
     [MonoModCustomMethodAttribute(nameof(MonoModRules.AddLevelTemplateCulling))]
     class AddLevelTemplateCullingAttribute : Attribute { }
 
+    /// <summary>
+    /// Patch `LevelTemplate.RenderContent` to support custom template colors.
+    /// </summary>
+    [MonoModCustomMethodAttribute(nameof(MonoModRules.PatchLevelTemplateRenderContents))]
+    class PatchLevelTemplateRenderContents : Attribute { }
+
     static partial class MonoModRules {
         public static void AddLevelTemplateCulling(ILContext il, CustomAttribute attrib) {
             var cursor = new ILCursor(il);
@@ -63,5 +85,34 @@ public static void AddLevelTemplateCulling(ILContext il, CustomAttribute attrib)
             cursor.Emit(OpCodes.Ret);
             cursor.MarkLabel(label);
         }
+
+        public static void PatchLevelTemplateRenderContents(ILContext il, CustomAttribute attrib) {
+            /*
+             * patch the `fgTilesColor` lookup to use `EditorColor` instead
+             * ```diff
+             * - Draw.Rect(X + solid.X, Y + solid.Y, solid.Width, solid.Height, Dummy ? dummyFgTilesColor : fgTilesColor[EditorColorIndex]);
+             * + Draw.Rect(X + solid.X, Y + solid.Y, solid.Width, solid.Height, Dummy ? dummyFgTilesColor : EditorColor);
+             * ```
+             */
+
+            MethodDefinition m_LevelTemplate_get_EditorColor = il.Method.DeclaringType.FindMethod("get_EditorColor")!;
+
+            ILCursor cursor = new(il);
+
+            /*
+             * IL_0170: ldsfld valuetype [FNA]Microsoft.Xna.Framework.Color[] Celeste.Editor.LevelTemplate::fgTilesColor
+             * IL_0175: ldarg.0
+             * IL_0176: ldfld int32 Celeste.Editor.LevelTemplate::EditorColorIndex
+             * IL_017b: ldelem [FNA]Microsoft.Xna.Framework.Color
+             */
+            cursor.GotoNext(MoveType.Before,
+                instr => instr.MatchLdsfld("Celeste.Editor.LevelTemplate", "fgTilesColor"),
+                instr => instr.MatchLdarg0(),
+                instr => instr.MatchLdfld("Celeste.Editor.LevelTemplate", "EditorColorIndex"),
+                instr => instr.MatchLdelemAny("Microsoft.Xna.Framework.Color"));
+            cursor.RemoveRange(4);
+            cursor.EmitLdarg0();
+            cursor.EmitCall(m_LevelTemplate_get_EditorColor);
+        }
     }
 }