Add support for hotspots on custom cursors

OpenDreamClient/Interface/DreamInterfaceManager.cs

@@ -1048,28 +1048,19 @@ public sealed class CursorHolder(IClyde clyde) {
     public readonly bool AllStateSet;
 
     public CursorHolder(IClyde clyde, DMIResource resource) : this(clyde) {
-        var allState = resource.GetStateAsImage("all", AtomDirection.South);
+        var allCursor = resource.GetStateAsImage(clyde, "all");
 
-        if (allState is not null) { //all overrides all possible states
-            BaseCursor = clyde.CreateCursor(allState, new(32, 32));
+        if (allCursor is not null) { //all overrides all possible states
+            BaseCursor = allCursor;
             DragCursor = BaseCursor;
             DropCursor = BaseCursor;
             OverCursor = BaseCursor;
             AllStateSet = true;
         } else {
-            var baseState = resource.GetStateAsImage("", AtomDirection.South);
-            var overState = resource.GetStateAsImage("over", AtomDirection.South);
-            var dragState = resource.GetStateAsImage("drag", AtomDirection.South);
-            var dropState = resource.GetStateAsImage("drop", AtomDirection.South);
-
-            if (baseState is not null)
-                BaseCursor = clyde.CreateCursor(baseState, new(32, 32));
-            if (overState is not null)
-                OverCursor = clyde.CreateCursor(overState, new(32, 32));
-            if (dragState is not null)
-                DragCursor = clyde.CreateCursor(dragState, new(32, 32));
-            if (dropState is not null)
-                DropCursor = clyde.CreateCursor(dropState, new(32, 32));
+            BaseCursor = resource.GetStateAsImage(clyde, "");
+            OverCursor = resource.GetStateAsImage(clyde, "over");
+            DragCursor = resource.GetStateAsImage(clyde, "drag");
+            DropCursor = resource.GetStateAsImage(clyde, "drop");
         }
     }
 }

OpenDreamClient/Resources/ResourceTypes/DMIResource.cs

@@ -51,21 +51,26 @@ private void ProcessDMIData() {
         return _states[stateName];
     }
 
-    public Image<Rgba32>? GetStateAsImage(string? stateName, AtomDirection dir) {
-        using Stream dmiStream = new MemoryStream(Data);
-        DMIParser.ParsedDMIDescription description = DMIParser.ParseDMI(dmiStream);
+    public ICursor? GetStateAsImage(IClyde clyde, string? stateName) {
+        using var dmiStream = new MemoryStream(Data);
+        var description = DMIParser.ParseDMI(dmiStream);
 
         dmiStream.Seek(0, SeekOrigin.Begin);
 
         Image<Rgba32> image = Image.Load<Rgba32>(dmiStream);
-        if (!(description.GetStateOrDefault(stateName)?.Directions.TryGetValue(dir, out var state) ?? false))
+        var state = description.GetStateOrDefault(stateName);
+        if (!(state?.Directions.TryGetValue(AtomDirection.South, out var frames) ?? false))
             return null;
 
-        var result = image.Clone(clone => {
-            clone.Resize(new Size(description.Width, description.Height));
-            clone.Crop(new Rectangle(state[0].X, state[0].Y, state[0].X + description.Width, state[0].Y + description.Height));
+        var stateImage = image.Clone(clone => {
+            var frame = frames[0];
+
+            clone.Crop(new Rectangle(frame.X, frame.Y, frame.X + description.Width, frame.Y + description.Height));
         });
-        return result;
+
+        var hotspot = state.Hotspot ?? (0, stateImage.Height - 1); // Default to the top-left
+        var cursor = clyde.CreateCursor(stateImage, hotspot);
+        return cursor;
     }
 
     public struct State {

OpenDreamShared/Resources/DMIParser.cs

@@ -127,6 +127,11 @@ public sealed class ParsedDMIState(string name) {
         public bool Loop = true;
         public bool Rewind;
 
+        /// <summary>
+        /// The part of the image considered the tip when this is used as a custom cursor
+        /// </summary>
+        public Vector2i? Hotspot;
+
         // TODO: This can only contain either 1, 4, or 8 directions. Enforcing this could simplify some things.
         public readonly Dictionary<AtomDirection, ParsedDMIFrame[]> Directions = new();
 
@@ -450,7 +455,16 @@ private static ParsedDMIDescription ParseDMIDescription(string dmiDescription, u
                         //TODO
                         break;
                     case "hotspot":
-                        //TODO
+                        if (currentState is null) break;
+                        var hotspotValues = value.Split(',');
+                        if (hotspotValues.Length != 3)
+                            throw new Exception($"Invalid hotspot value \"{value}\"");
+
+                        var hotspotX = int.Parse(hotspotValues[0]);
+                        var hotspotY = int.Parse(hotspotValues[1]);
+                        // TODO: 3rd value? Something to do with what frames the hotspot applies to apparently
+
+                        currentState.Hotspot = (hotspotX, hotspotY);
                         break;
                     default:
                         throw new Exception($"Invalid key \"{key}\" in DMI description");