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 );
});

var snap = cytosnap();

// or

var snap = new cytosnap();

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

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

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

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