Connector annotations in EJ2 JavaScript Diagram control

15 Dec 202414 minutes to read

Annotations of a connector can be positioned using the following properties of Annotation class.

Offset
Alignment
Displacement
SegmentAngle
HorizontalAlignment
VerticalAlignment
Margin

Annotation offset

The offset for pathAnnotation is of type number and ranges from 0 to 1, from the source to the target point of the connector. By default, the offset value for a connector annotation is 0.5.

The following code illustrates, how to set offset for the connector.

index.js
index.html
var connectors = [
  {
    sourcePoint: { x: 200, y: 100 },
    targetPoint: { x: 300, y: 200 },
    type: 'Straight',
    //Path annotation offset
    annotations: [{ content: 'annotation', offset: 0.2 }],
  },
];
// initialize Diagram component

var diagram = new ej.diagrams.Diagram(
  {
    width: '100%',
    height: '600px',
    connectors: connectors,
  },
  '#element'
);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Diagram</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-buttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-popups/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-splitbuttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-diagrams/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-navigations/styles/fabric.css" rel="stylesheet">
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

The following image shows the position of the annotation with respect to different offsets.

PathAnnotation offset

Annotation alignment

The connector’s annotation can be aligned over its segment path using the alignment property of annotation.

The following code example illustrates how to align connector annotations.

index.js
index.html
var node = {
    id: 'node1',
    // Position of the node
    offsetX: 100,
    offsetY: 100,
    // Size of the node
    width: 100,
    height: 100,
    style: { fill: '#6BA5D7', strokeColor: 'white' },
    annotations: [{ content: 'Task1' }],
  };
  
  var node2 = {
    id: 'node2',
    // Position of the node
    offsetX: 300,
    offsetY: 100,
    // Size of the node
    width: 100,
    height: 100,
    style: { fill: '#6BA5D7', strokeColor: 'white' },
    annotations: [{ content: 'Task2' }],
  };
  
  var connector = {
    sourceID: 'node1',
    targetID: 'node2',
    type: 'Orthogonal',
    style: { strokeColor: '#6BA5D7', strokeWidth: 2 },
    targetDecorator: { shape: 'None' },
    annotations: [
      { content: '0', offset: 0, alignment: 'Before' },
      { content: '1', offset: 1, alignment: 'After' },
    ],
  };
  
  // initialize Diagram component
  
  var diagram = new ej.diagrams.Diagram(
    {
      width: '100%',
      height: '600px',
      nodes: [node, node2],
      connectors: [connector],
    },
    '#element'
  );
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Diagram</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-buttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-popups/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-splitbuttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-diagrams/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-navigations/styles/fabric.css" rel="stylesheet">
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Displacement of annotation

Displacement refers displacement of an annotation from its actual position. A connector annotation can be displaced to a particular distance by using a displacement property of the pathAnnotation. The following example shows how to set displacement for the connector annotation.

index.js
index.html
var connectors = [
  {
    sourcePoint: { x: 200, y: 100 },
    targetPoint: { x: 500, y: 100 },
    type: 'Straight',
    //Path annotation offset
    annotations: [
      {
        content: 'annotation',
        offset: 0.2,
        alignment: 'After',
        displacement: { x: 50, y: 50 },
      },
    ],
  },
];
// initialize Diagram component

var diagram = new ej.diagrams.Diagram(
  {
    width: '100%',
    height: '600px',
    connectors: connectors,
  },
  '#element'
);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Diagram</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-buttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-popups/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-splitbuttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-diagrams/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-navigations/styles/fabric.css" rel="stylesheet">
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

NOTE

Displacement is only applicable when we use alignment as After or Before.

Segment angle for annotation

The segmentAngle property is used to rotate the annotation based on the connectors segment direction. By default, annotation will be rotated in the connector path. When you set segmentAngle as true, annotation will be rotated from its position based on the connector segment direction. The following code illustrates, how to set segment angle.

index.js
index.html
var connectors = [
  {
    sourcePoint: { x: 200, y: 100 },
    targetPoint: { x: 500, y: 300 },
    type: 'Orthogonal',
    //Path annotation offset
    annotations: [
      {
        content: 'annotation',
        offset: 0.2,
        //Segment angle
        segmentAngle: true,
      },
    ],
  },
];
// initialize Diagram component

var diagram = new ej.diagrams.Diagram(
  {
    width: '100%',
    height: '600px',
    connectors: connectors,
  },
  '#element'
);
<!DOCTYPE html><html lang="en"><head>
    <title>EJ2 Diagram</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta name="description" content="Typescript UI Controls">
    <meta name="author" content="Syncfusion">
    <link href="index.css" rel="stylesheet">
    
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-base/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-buttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-popups/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-splitbuttons/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-diagrams/styles/material.css" rel="stylesheet">
    <link href="https://cdn.syncfusion.com/ej2/28.1.33/ej2-navigations/styles/fabric.css" rel="stylesheet">
    
<script src="https://cdn.syncfusion.com/ej2/28.1.33/dist/ej2.min.js" type="text/javascript"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    
    <div id="container">
        <div id="element"></div>
    </div>


<script>
var ele = document.getElementById('container');
if(ele) {
  ele.style.visibility = "visible";
}   
      </script>
<script src="index.js" type="text/javascript"></script>
</body></html>

Segment angle	Output
True
False