@iriograph/layout-elk

日本語

Optional ELK.js Layered layout adapter for @iriograph/core. It keeps the semantic document and engine-specific ELK options separate: a document stores only a stable layoutRef, while this package translates the Core layout request into ELK's graph model.

Install

npm install --save-exact @iriograph/core @iriograph/layout-elk

Use the bundled engine

import { LayoutAdapterRegistry } from "@iriograph/core";
import {
  ELK_LAYOUT_REFS,
  ElkLayeredLayoutAdapter,
} from "@iriograph/layout-elk";

const layouts = new LayoutAdapterRegistry([
  new ElkLayeredLayoutAdapter(ELK_LAYOUT_REFS.layeredLr, "LR"),
  new ElkLayeredLayoutAdapter(ELK_LAYOUT_REFS.layeredTb, "TB"),
]);

The default engine lazily loads elkjs/lib/elk.bundled.js. Applications that need a browser Worker can inject an engine or a lazy factory. The injected object only needs the public ElkLayoutEngine contract, so Worker construction and asset URLs remain host responsibilities.

import ELK from "elkjs/lib/elk-api.js";
import { ElkLayeredLayoutAdapter } from "@iriograph/layout-elk";

const adapter = new ElkLayeredLayoutAdapter("urn:example:layout:worker", "LR", {
  engineFactory: {
    create: () => new ELK({
      workerUrl: new URL("./elk-worker.min.js", import.meta.url).toString(),
    }),
  },
});

Do not store ELK option keys in an Iriograph document. Direction, spacing, containment, node dimensions and routing intent are translated from the Core request by this adapter.

Fixed geometry

ELK Layered does not provide a hard guarantee for arbitrary pinned positions. When a request contains a pinned element or placement: "user", this adapter therefore does not run ELK and does not restore coordinates after routing. It uses Core's deterministic conservative layout instead, preserves fixed geometry exactly, reroutes every edge against the resulting geometry, and returns diagnostics describing the fallback or an impossible fixed constraint.

Manual waypoints are retained as view geometry. Every result contains geometry for every input element and a complete source-to-target route for every edge; missing, invalid, or failed engine output is diagnosed and completed through a deterministic fallback. This is the adapter's declared, backward-compatible fallbackPolicy: "standard". A host that requires ELK-only execution can set fallbackPolicy: "none"; failures then return diagnostics and never invoke a different layout engine.

License notice

This Iriograph adapter is MIT licensed. See LICENSE.

This package depends on ELK.js. ELK.js declares EPL-2.0 OR GPL-3.0-or-later; review the applicable license terms when redistributing a bundle containing it. Iriograph does not copy ELK engine options or code into saved documents.