Double Link

by Roman Bruckner

HTML

<html>
<head>
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/jointjs/3.6.2/joint.css" />
</head>
<body>
      <!-- content -->
      <div id="paper"></div>

      <!-- dependencies -->
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.1/jquery.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.20/lodash.min.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/backbone.js/1.4.0/backbone.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jointjs/3.6.2/joint.js"></script>
    
    </body>
</html>

JavaScript

var graph = new joint.dia.Graph({}, {
  cellNamespace: joint.shapes
});

const paper = new joint.dia.Paper({
  el: document.getElementById('paper'),
  width: 800,
  height: 900,
  model: graph,
  defaultConnectionPoint: {
    name: 'boundary'
  },
  cellViewNamespace: joint.shapes,
  gridSize: 10,
  async: true,
  sorting: joint.dia.Paper.sorting.APPROX,
  linkPinning: false,
  defaultLink: () => new joint.shapes.standard.DoubleLink()
});

// Example

var el1 = new joint.shapes.standard.Rectangle({
  position: {
    x: 10,
    y: 170
  },
  size: {
    width: 100,
    height: 90
  },
  attrs: {
    label: {
      text: 'A'
    }
  }
});
var el2 = new joint.shapes.standard.Rectangle({
  position: {
    x: 400,
    y: 170
  },
  size: {
    width: 100,
    height: 90
  },
  attrs: {
    label: {
      text: 'B'
    }
  }
});

const gap = 10;
const lineWidth = 2;

const l1 = new joint.shapes.standard.DoubleLink({
  source: {
    id: el1.id
  },
  target: {
    id: el2.id
  },
  z: -1,
  attrs: {
    line: {
      targetMarker: null,
      stroke: '#fff',
      strokeWidth: gap,
      strokeLinecap: 'square'
    },
    outline: {
      stroke: '#333',
      strokeWidth: gap + 2 * lineWidth,
      strokeLinecap: 'square'
    }
  }
});

graph.addCells([el1, el2, l1]);