Fix reroutes lost when dropping output links on reroute (#820)

Blocks attempts to drag links from an output onto a reroute in any of
the links.

src/canvas/FloatingRenderLink.ts

@@ -96,6 +96,15 @@ export class FloatingRenderLink implements RenderLink {
     this.fromPos = fromReroute.pos
   }
 
+  canConnectToReroute(reroute: Reroute): boolean {
+    if (this.toType === "input") {
+      if (reroute.origin_id === this.inputNode?.id) return false
+    } else {
+      if (reroute.origin_id === this.outputNode?.id) return false
+    }
+    return true
+  }
+
   connectToInput(node: LGraphNode, input: INodeInputSlot, _events?: LinkConnectorEventTarget): void {
     const floatingLink = this.link
     floatingLink.target_id = node.id

src/canvas/LinkConnector.ts

@@ -538,6 +538,7 @@ export class LinkConnector {
 
       for (const renderLink of this.renderLinks) {
         if (renderLink.toType !== "output") continue
+        if (!renderLink.canConnectToReroute(reroute)) continue
         if (isValidConnectionToOutput(renderLink, node, output)) return true
       }
     }

src/canvas/MovingRenderLink.ts

@@ -86,6 +86,15 @@ export class MovingRenderLink implements RenderLink {
     this.fromSlotIndex = this.toType === "input" ? outputIndex : inputIndex
   }
 
+  canConnectToReroute(reroute: Reroute): boolean {
+    if (this.toType === "input") {
+      if (reroute.origin_id === this.inputNode.id) return false
+    } else {
+      if (reroute.origin_id === this.outputNode.id) return false
+    }
+    return true
+  }
+
   connectToInput(inputNode: LGraphNode, input: INodeInputSlot, events: LinkConnectorEventTarget): LLink | null | undefined {
     if (input === this.inputSlot) return
 

src/canvas/ToOutputRenderLink.ts

@@ -31,6 +31,11 @@ export class ToOutputRenderLink implements RenderLink {
       : this.node.getInputPos(inputIndex)
   }
 
+  canConnectToReroute(reroute: Reroute): boolean {
+    if (reroute.origin_id === this.node.id) return false
+    return true
+  }
+
   connectToOutput(node: LGraphNode, output: INodeOutputSlot, events: LinkConnectorEventTarget) {
     const { node: inputNode, fromSlot, fromReroute } = this
     if (inputNode) return

test/LinkConnector.integration.test.ts

@@ -361,6 +361,37 @@ describe("LinkConnector Integration", () => {
 
       validateIntegrityFloatingRemoved()
     })
+
+    test("Should prevent dragging from an output to a child reroute", ({ graph, connector, floatingReroute }) => {
+      const manyOutputsNode = graph.getNodeById(4)!
+
+      const reroute7 = graph.reroutes.get(7)!
+      const reroute10 = graph.reroutes.get(10)!
+      const reroute13 = graph.reroutes.get(13)!
+
+      const canvasX = reroute7.pos[0]
+      const canvasY = reroute7.pos[1]
+      const reroute7Event = { canvasX, canvasY } as any
+
+      const toSortedRerouteChain = (linkIds: number[]) => linkIds
+        .map(x => graph.links.get(x)!)
+        .map(x => LLink.getReroutes(graph, x))
+        .sort((a, b) => a.at(-1)!.id - b.at(-1)!.id)
+
+      const reroutesBefore = toSortedRerouteChain(manyOutputsNode.outputs[0].links!)
+
+      connector.moveOutputLink(graph, manyOutputsNode.outputs[0])
+      expect(connector.isRerouteValidDrop(reroute7)).toBe(false)
+      expect(connector.isRerouteValidDrop(reroute10)).toBe(false)
+      expect(connector.isRerouteValidDrop(reroute13)).toBe(false)
+      connector.dropLinks(graph, reroute7Event)
+
+      const reroutesAfter = toSortedRerouteChain(manyOutputsNode.outputs[0].links!)
+      expect(reroutesAfter).toEqual(reroutesBefore)
+
+      expect(graph.floatingLinks.size).toBe(1)
+      expect(floatingReroute.linkIds.size).toBe(0)
+    })
   })
 
   describe("Floating links", () => {