The ELK layout algorithm adapter for Cytoscape.js

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The elk layout algorithm adapter for Cytoscape.js
ELK is a set of layout algorithms implemented by the Eclipse Foundation in Java. The source code is compiled to JS by the ELK.js project using GWT. This Cytoscape extension adds support for the ELK layout aglorithms in Cytoscape.


Cytoscape.js ^3.2.0 elkjs ^0.7.0

Usage instructions

Download the library: via npm or yarn: npm install cytoscape-elk or yarn add cytoscape-elk, via direct download in the repository (probably from a tag).
Import the library as appropriate for your project:
ES import:
import cytoscape from 'cytoscape';
import elk from 'cytoscape-elk';

cytoscape.use( elk );

CommonJS require:
let cytoscape = require('cytoscape');
let elk = require('cytoscape-elk');

cytoscape.use( elk ); // register extension

require(['cytoscape', 'cytoscape-elk'], function( cytoscape, elk ){
  elk( cytoscape ); // register extension

Plain HTML/JS has the extension registered for you automatically, because no require() is needed.


var options = {
  nodeDimensionsIncludeLabels: false, // Boolean which changes whether label dimensions are included when calculating node dimensions
  fit: true, // Whether to fit
  padding: 20, // Padding on fit
  animate: false, // Whether to transition the node positions
  animateFilter: function( node, i ){ return true; }, // Whether to animate specific nodes when animation is on; non-animated nodes immediately go to their final positions
  animationDuration: 500, // Duration of animation in ms if enabled
  animationEasing: undefined, // Easing of animation if enabled
  transform: function( node, pos ){ return pos; }, // A function that applies a transform to the final node position
  ready: undefined, // Callback on layoutready
  stop: undefined, // Callback on layoutstop
  elk: {
    // All options are available at
    // 'org.eclipse.' can be dropped from the identifier. The subsequent identifier has to be used as property key in quotes.
    // E.g. for 'org.eclipse.elk.direction' use:
    // 'elk.direction'
    // Enums use the name of the enum as string e.g. instead of Direction.DOWN use:
    // 'elk.direction': 'DOWN'
    // The main field to set is `algorithm`, which controls which particular layout algorithm is used.
    // Example (downwards layered layout):
    'algorithm': 'layered',
    'elk.direction': 'DOWN',
  priority: function( edge ){ return null; }, // Edges with a non-nil value are skipped when geedy edge cycle breaking is enabled

cy.layout( options ).run();

The set of options.elk.algorithm values that are supported by ELK.js follows:
  • box : (Demo) (Docs) Pack the nodes like boxes.
  • disco : (Demo) (Docs) Pack the (disconnected) components. A secondary layout may be applied to each component via options.elk.componentLayoutAlgorithm.
  • force : (Demo) (Docs) Apply a basic force-directed layout.
  • layered : (Demo) (Docs) Apply a hierarchical layout, appropriate for DAGs and trees.
  • mrtree : (Demo (Docs) Apply a traditional, hierarchical tree layout.
  • random : (Demo) (Docs) Apply random positions to the nodes.
  • stress : (Demo) (Docs) Apply a force-directed layout.

See the ELK.js documentation and the ELK algorithm options documentation for more information.

Build targets

  • npm run test : Run Mocha tests in ./test
  • npm run build : Build ./src/** into cytoscape.js-elk
  • npm run watch : Automatically build on changes with live reloading (N.b. you must already have an HTTP server running)
  • npm run dev : Automatically build on changes with live reloading with webpack dev server
  • npm run lint : Run eslint on the source

N.b. all builds use babel, so modern ES features can be used in the src.

Publishing instructions

This project is set up to automatically be published to npm. To publish:
  1. Build the extension : npm run build
  2. Commit the build : git commit -am "Build for release"
  3. Bump the version number and tag: npm version major|minor|patch
  4. Push to origin: git push && git push --tags
  5. Publish to npm: npm publish .