Free Drawing

by Roman Bruckner

HTML

<html>
<head>
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/jointjs/3.2.0/joint.css" />
</head>
<body>
      <!-- content -->
      <div id="paper"></div>

      <!-- dependencies -->
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.js"></script>
        <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.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/3.2.0/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,
  cellViewNamespace: joint.shapes
});

paper.on('blank:pointerdown', function(evt, x, y) {
  const polyline = V('polyline', {
    'stroke': 'red',
    'fill': 'none'
  });
  polyline.appendTo(this.svg);
  evt.data = {
    polyline,
    points: [
      [x, y]
    ]
  };
});


paper.on('blank:pointermove', function(evt, x, y) {
  const {
    points,
    polyline
  } = evt.data;
  points.push([x, y]);
  polyline.attr('points', points.join(' '));
});

paper.on('blank:pointerup', function(evt, x, y) {
  const {
    points,
    polyline
  } = evt.data;
  console.log(points);
  // polyline.remove()
  // Replace with an actual shape
  const geometry = new g.Polyline(points.join(' '));
  geometry.simplify({ threshold: 0.8 });
  polyline.attr('points', geometry.serialize());
});