gistfile1.js

var SampleDiagram = Ds.Diagram.extend({
  el: 'canvas'
});

var Circle = Ds.Shape.extend({
  figure: {
    type: 'circle',
    r: 30,
    fill: 'red',
    stroke: 'rgb(120, 120, 200)',
    'stroke-width': 2
  }
});

var d = new SampleDiagram({ width: 1200, height: 800 });
var c = new Circle({ x: 100, y: 200, diagram: d });
d.render();