Add Subgraphs (#1000)

src/subgraph/EmptySubgraphOutput.ts

@@ -0,0 +1,39 @@
+import type { SubgraphOutputNode } from "./SubgraphOutputNode"
+import type { INodeOutputSlot, Point } from "@/interfaces"
+import type { LGraphNode } from "@/LGraphNode"
+import type { RerouteId } from "@/Reroute"
+
+import { LLink } from "@/LLink"
+import { nextUniqueName } from "@/strings"
+import { zeroUuid } from "@/utils/uuid"
+
+import { SubgraphOutput } from "./SubgraphOutput"
+
+/**
+ * A virtual slot that simply creates a new output slot when connected to.
+ */
+export class EmptySubgraphOutput extends SubgraphOutput {
+  declare parent: SubgraphOutputNode
+
+  constructor(parent: SubgraphOutputNode) {
+    super({
+      id: zeroUuid,
+      name: "",
+      type: "",
+    }, parent)
+  }
+
+  override connect(slot: INodeOutputSlot, node: LGraphNode, afterRerouteId?: RerouteId): LLink | undefined {
+    const { subgraph } = this.parent
+    const existingNames = subgraph.outputs.map(x => x.name)
+
+    const name = nextUniqueName(slot.name, existingNames)
+    const output = subgraph.addOutput(name, String(slot.type))
+    return output.connect(slot, node, afterRerouteId)
+  }
+
+  override get labelPos(): Point {
+    const [x, y, , height] = this.boundingRect
+    return [x, y + height * 0.5]
+  }
+}