Drawing A Shape

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 rect = new joint.shapes.standard.Rectangle({
    position: {
      x: x,
      y: y
    },
    size: {
      width: 1,
      height: 1
    }
  });
	rect.addTo(graph);
  evt.data = {
    rect,
    ox: x,
    oy: y
  };
});


paper.on('blank:pointermove', function(evt, x, y) {
  const {
    ox,
    oy,
    rect
  } = evt.data;
  const bbox = new g.Rect(ox, oy, x - ox, y - oy);
  if (bbox.width === 0) bbox.width = 1;
  if (bbox.height === 0) bbox.height = 1;
  bbox.normalize();
  evt.data.bbox = bbox;
  rect.set({
    position: { x: bbox.x, y: bbox.y },
    size: { width: bbox.width, height: bbox.height }
  });
});

paper.on('blank:pointerup', function(evt, x, y) {
  const {
    ox,
    oy,
    rect,
    bbox
  } = evt.data;
  if (bbox) return;
  // do not leave tiny rectangles in the graph
  rect.remove();
});