cytoscape-edgehandles

Description

This extension creates handles on nodes that can be dragged to create edges between nodes (demo, snapping demo, compound demo, compound snapping demo)

Dependencies

• Cytoscape.js ^3.2.0

Usage instructions

Download the library:

• via npm: npm install cytoscape-edgehandles,
• via bower: bower install cytoscape-edgehandles, or
• 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 edgehandles from 'cytoscape-edgehandles';

cytoscape.use( edgehandles );

CommonJS require:

let cytoscape = require('cytoscape');
let edgehandles = require('cytoscape-edgehandles');

cytoscape.use( edgehandles ); // register extension

AMD:

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

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

Initialisation

You initialise the extension on the Cytoscape instance:

let cy = cytoscape({
  container: document.getElementById('#cy'),
	/* ... */
});

// the default values of each option are outlined below:
let defaults = {
  preview: true, // whether to show added edges preview before releasing selection
  hoverDelay: 150, // time spent hovering over a target node before it is considered selected
  handleNodes: 'node', // selector/filter function for whether edges can be made from a given node
  snap: false, // when enabled, the edge can be drawn by just moving close to a target node
  snapThreshold: 50, // the target node must be less than or equal to this many pixels away from the cursor/finger
  snapFrequency: 15, // the number of times per second (Hz) that snap checks done (lower is less expensive)
  noEdgeEventsInDraw: false, // set events:no to edges during draws, prevents mouseouts on compounds
  disableBrowserGestures: true, // during an edge drawing gesture, disable browser gestures such as two-finger trackpad swipe and pinch-to-zoom
  handlePosition: function( node ){
    return 'middle top'; // sets the position of the handle in the format of "X-AXIS Y-AXIS" such as "left top", "middle top"
  },
  handleInDrawMode: false, // whether to show the handle in draw mode
  edgeType: function( sourceNode, targetNode ){
    // can return 'flat' for flat edges between nodes or 'node' for intermediate node between them
    // returning null/undefined means an edge can't be added between the two nodes
    return 'flat';
  },
  loopAllowed: function( node ){
    // for the specified node, return whether edges from itself to itself are allowed
    return false;
  },
  nodeLoopOffset: -50, // offset for edgeType: 'node' loops
  nodeParams: function( sourceNode, targetNode ){
    // for edges between the specified source and target
    // return element object to be passed to cy.add() for intermediary node
    return {};
  },
  edgeParams: function( sourceNode, targetNode, i ){
    // for edges between the specified source and target
    // return element object to be passed to cy.add() for edge
    // NB: i indicates edge index in case of edgeType: 'node'
    return {};
  },
  ghostEdgeParams: function(){
    // return element object to be passed to cy.add() for the ghost edge
    // (default classes are always added for you)
    return {};
  },
  show: function( sourceNode ){
    // fired when handle is shown
  },
  hide: function( sourceNode ){
    // fired when the handle is hidden
  },
  start: function( sourceNode ){
    // fired when edgehandles interaction starts (drag on handle)
  },
  complete: function( sourceNode, targetNode, addedEles ){
    // fired when edgehandles is done and elements are added
  },
  stop: function( sourceNode ){
    // fired when edgehandles interaction is stopped (either complete with added edges or incomplete)
  },
  cancel: function( sourceNode, cancelledTargets ){
    // fired when edgehandles are cancelled (incomplete gesture)
  },
  hoverover: function( sourceNode, targetNode ){
    // fired when a target is hovered
  },
  hoverout: function( sourceNode, targetNode ){
    // fired when a target isn't hovered anymore
  },
  previewon: function( sourceNode, targetNode, previewEles ){
    // fired when preview is shown
  },
  previewoff: function( sourceNode, targetNode, previewEles ){
    // fired when preview is hidden
  },
  drawon: function(){
    // fired when draw mode enabled
  },
  drawoff: function(){
    // fired when draw mode disabled
  }
};

let eh = cy.edgehandles( defaults );

API

The object returned by cy.edgehandles() has several functions available on it:

• start( sourceNode ) : manually start the gesture (as if the handle were already held)
• stop() : manually completes or cancels the gesture
• hide() : remove the handle node from the graph
• disable() : disables edgehandles behaviour
• enable() : enables edgehandles behaviour
• enableDrawMode() : turn on draw mode (the entire node body acts like the handle)
• disableDrawMode() : turn off draw mode
• destroy() : remove edgehandles behaviour

Classes

These classes can be used for styling the graph as it interacts with the extension:

• eh-handle : The handle node
• eh-source : The source node
• eh-target : A target node
• eh-preview : Preview elements (used with options.preview: true)
• eh-hover : Added to nodes as they are hovered over as targets
• eh-ghost-node : The ghost node (target)
• eh-ghost-edge : The ghost handle line edge
• eh-ghost : A ghost element
• eh-presumptive-target : A node that, during an edge drag, may become a target when released
• eh-preview-active : Applied to the source, target, and ghost edge when the preview is active

Events

During the course of a user's interaction with the extension, several events are generated and triggered on the core. Each event callback has a number of extra parameters, and certain events have associated positions.

• ehshow : when the handle is shown
  • (event, sourceNode)
  • event.position : handle position
• ehhide : when the handle is hidden
  • (event, sourceNode)
  • event.position : handle position
• ehstart : when the edge creation gesture starts
  • (event, sourceNode)
  • event.position : handle position
• ehcomplete : when the edge creation gesture is successfully completed
  • (event, sourceNode, targetNode, addedEles)
  • event.position : cursor/finger position
• ehstop : when the edge creation gesture is stopped (either successfully completed or cancelled)
  • (event, sourceNode)
  • event.position : cursor/finger position
• ehcancel : when the edge creation gesture is cancelled
  • (event, sourceNode, cancelledTargets)
  • event.position : cursor/finger position
• ehhoverover : when hovering over a target
  • (event, sourceNode, targetNode)
  • event.position : cursor/finger position
• ehhoverout : when leaving a target node
  • (event, sourceNode, targetNode)
  • event.position : cursor/finger position
• ehpreviewon : when a preview is shown
  • (event, sourceNode, targetNode, previewEles)
  • event.position : cursor/finger position
• ehpreviewoff : when the preview is removed
  • (event, sourceNode, targetNode, previewEles)
  • event.position : cursor/finger position
• ehdrawon : when draw mode is enabled
  • (event)
• ehdrawoff : when draw mode is disabled
  • (event)

Example binding:

cy.on('ehcomplete', (event, sourceNode, targetNode, addedEles) => {
	let { position } = event;

  // ...
});

Build targets

• npm run test : Run Mocha tests in ./test
• npm run build : Build ./src/** into cytoscape-edgehandles.js
• 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 and bower. To publish:

1. Build the extension : npm run build:release
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 .
6. If publishing to bower for the first time, you'll need to run bower register cytoscape-edgehandles https://github.com/cytoscape/edgehandles.gita
7. Make a new release for Zenodo.