A Node.js package that renders images of Cytoscape.js graphs on the server using PhantomJS
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README.md

Cytosnap

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Render graphs on the server side with Cytoscape.js, getting image files as output

This project was initiated at MozSprint 2016

How to contribute

Please refer to CONTRIBUTING.md.

Usage

Quick start example:

var cytosnap = require('cytosnap');
var snap = cytosnap();

snap.start().then(function(){
  return snap.shot({
    elements: [ // http://js.cytoscape.org/#notation/elements-json
      { data: { id: 'foo' } },
      { data: { id: 'bar' } },
      { data: { source: 'foo', target: 'bar' } }
    ],
    layout: { // http://js.cytoscape.org/#init-opts/layout
      name: 'grid'
    },
    style: [ // http://js.cytoscape.org/#style
      {
        selector: 'node',
        style: {
          'background-color': 'red'
        }
      },
      {
        selector: 'edge',
        style: {
          'line-color': 'red'
        }
      }
    ],
    resolvesTo: 'base64uri',
    format: 'png',
    width: 640,
    height: 480,
    background: 'transparent'
  });
}).then(function( img ){
  // do whatever you want with img
  console.log( img );
});

cytosnap()

Initialise an instance of Cytosnap:

var snap = cytosnap();

// or

var snap = new cytosnap();

snap.start( [next] )

Start up the Cytosnap instance, snap, so we can request that it generate images:

Promise style:

snap.start().then(function(){ // promise resolved on start
  console.log('chained start promise');
});

Node callback style using next:

snap.start(function( err ){
  console.log('called on start');
});

snap.shot( options, [next] )

Generate a snapshot of a graph:

var defaultOptions = {
  // cytoscape.js options
  elements: undefined, // cytoscape.js elements json
  style: undefined, // a cytoscape.js stylesheet in json format (or a function that returns it)
  layout: undefined // a cytoscape.js layout options object (or a function that returns it)
  // (specifying style or layout via a function is useful in cases where you can't send properly serialisable json)

  // image export options
  resolvesTo: 'base64uri', // output, one of 'base64uri' (default), 'base64', 'stream', or 'json' (export resultant node positions from layout)
  format: 'png', // 'png' or 'jpg'/'jpeg' (n/a if resolvesTo: 'json')
  quality: 85, // quality of image if exporting jpg format, 0 (low) to 100 (high)
  background: 'transparent', // a css colour for the background (transparent by default)
  width: 200, // the width of the image in pixels
  height: 200 // the height of the image in pixels
};

// promise style
snap.shot( defaultOptions ).then(function( img ){
  console.log('on resolve');
}).catch(function( err ){
  console.log('on error');
});

// node callback style
snap.shot( defaultOptions, function( err, img ){
  console.log('on error or resolve');
} );

snap.stop( [next] )

Stop the Cytosnap instance:

Promise style:

snap.stop().then(function(){ // promise resolved on stop
  console.log('chained stop promise');
});

Node callback style using next:

snap.stop(function( err ){
  console.log('called on stop');
});

Targets

  • npm test : Run Mocha tests in ./test