feat: add typed EventMap and DefinedEventMap for Paper and Graph

- Add LiteralUnion<T> and ExcludeIndexSignature<T> utility types
- Add mvc.EventCallbackMap<T> generic utility for partial event maps
- Add Paper.DefinedEventMap (EventMap without index signature) for IDE autocomplete
- Add paper:mouseenter and paper:mouseleave to Paper.EventMap
- Add typed on() overloads to Paper using DefinedEventMap
- Add Graph.EventMap with cell, change:*, layer, and batch events
- Add Graph.DefinedEventMap and typed on() overloads to Graph
- Preserve backwards compatibility: EventMap keeps index signature

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kumilingus

packages/joint-core/test/ts/index.test.ts

@@ -211,9 +211,6 @@ cellView.listenTo(paper, {
     }
 } as joint.dia.Paper.EventMap);
 
-
-
-
 class AttributeHighlighterView extends joint.dia.HighlighterView<{ attribute: string; }> {
     preinitialize() {
         this.UPDATE_ATTRIBUTES = function() { return [this.options.attribute]; };

packages/joint-core/types/joint.d.ts

@@ -360,8 +360,8 @@ export namespace dia {
             'move': (cell: Cell, options: Options) => void;
             'changeId': (cell: Cell, previousId: Cell.ID, options: Options) => void;
             // layer events
-            'layer:add': (layer: GraphLayer, options: Options) => void;
-            'layer:remove': (layer: GraphLayer, options: Options) => void;
+            'layer:add': (layer: GraphLayer, collection: GraphLayerCollection, options: Options) => void;
+            'layer:remove': (layer: GraphLayer, collection: GraphLayerCollection, options: Options) => void;
             'layer:change': (layer: GraphLayer, options: Options) => void;
             [layerChangeEvent: `layer:change:${string}`]: (layer: GraphLayer, newValue: any, options: Options) => void;
             'layer:default': (layer: GraphLayer, options: Options) => void;
@@ -374,6 +374,7 @@ export namespace dia {
         }
 
         type DefinedEventMap = ExcludeIndexSignature<EventMap>;
+
     }
 
     class Graph<A extends ObjectHash = Graph.Attributes, S = dia.ModelSetOptions> extends mvc.Model<A, S> {
@@ -409,7 +410,7 @@ export namespace dia {
             context?: any
         ): this;
 
-        on<E extends Partial<Graph.DefinedEventMap> & { [key: string]: mvc.EventHandler }>(
+        on<E extends mvc.EventCallbackMap<Graph.DefinedEventMap>>(
             events: E,
             context?: any
         ): this;
@@ -2222,7 +2223,7 @@ export namespace dia {
             context?: any
         ): this;
 
-        on<E extends Partial<Paper.DefinedEventMap> & { [key: string]: mvc.EventHandler }>(
+        on<E extends mvc.EventCallbackMap<Paper.DefinedEventMap>>(
             events: E,
             context?: any
         ): this;
@@ -3641,6 +3642,12 @@ export namespace mvc {
         [event: string]: EventHandler;
     }
 
+    /**
+     * A partial map of known event callbacks, plus any custom string events.
+     * Use with a DefinedEventMap to get autocomplete for known events.
+     */
+    type EventCallbackMap<T> = Partial<T> & { [key: string]: EventHandler };
+
     const Events: Events;
     interface Events extends EventsMixin {}