Link to Vertex Connection

by Roman Bruckner

HTML

<html>
<head>
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/jointjs/3.6.5/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/4.17.20/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/3.6.5/joint.js"></script>
    
    </body>
</html>

JavaScript

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

const vertexAnchor = function(view, magnet, ref, opt) {
    const vertices = view.model.vertices();
    const { index = 0 } = opt;
    if (vertices.length > index) {
        return new g.Point(vertices[index]);
    }
    return view.sourcePoint;
};

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,
    connectionStrategy: function(end, view, magnet, coords) {
        if (view.model.isElement()) return end;
        const vertices = view.model.vertices();
        if (vertices.length === 0) return end;
        const vertex = coords.chooseClosest(vertices);
        const index = vertices.findIndex(v => vertex.equals(v));
        end.anchor = {
            name: 'vertexAnchor',
            args: { index }
        };
        return end;

    },
    defaultLink: (elementView, magnet) => {
        return new joint.shapes.standard.Link({
            attrs: {
                line: {
                    stroke: 'red'
                }
            }
        });
    },
    linkAnchorNamespace: {
        ... joint.linkAnchors,
        vertexAnchor
    },
    validateConnection: (srcView, _, tgtView) => {
        const src = srcView.model;
        const tgt = tgtView.model;
        if (src === tgt) return false;
        return true;
    },
});



// Example

var el1 = new joint.shapes.standard.Rectangle({
    position: {
        x: 10,
        y: 170
    },
    size: {
        width: 100,
        height: 90
    }
});

var el2 = el1.clone().position(300, 100);
var el3 = el1.clone().position(300, 400);


const l1 = new joint.shapes.standard.Link({
    source: {
        id: el2.id
    },
    target: {
        id: el3.id
    },
 ...