Gauge legend in EJ2 TypeScript Circular gauge control

19 Apr 202319 minutes to read

Legend provides valuable information for interpreting what the circular gauge axis range displays, and they can be represented in various colors, shapes, and other identifiers based on the data. It gives a breakdown of what each symbol represents in the axis range of circular gauge.

You can add the legend for circular gauge ranges by setting the visible property of legendSettings to true.

Legend customization

Customization option is also provided for the legend shape, alignment, and position.

Position and alignment

The position of the legend is used to place legend in various positions. You can use the position property in legendSettings. Based on the position, the legend item will be aligned. The following options are available to customize the legend position:

Top
Bottom
Left
Right
Custom
Auto

The legend alignment is used to align the legend items in specific location. You can use the alignment property in legendSettings to align the legend items. The following options are available to customize the legend alignment:

Near
Center
Far

The legends can also be positioned to absolute position using the location.x and location.y properties available in legendSettings.

Legend size

The legend size can be modified using the height and width properties in legendSettings.

Legend opacity

To specify the transparency for legend shape, set the opacity property in legendSettings.

Legend shape

To change the legend item shape, specify the desired shape in the shape property of the legend. By default, the shape of the legend is circle.

It also supports the following shapes:

Circle
Rectangle
Diamond
Triangle
InvertedTriangle
Image

You can customize a shape using the shapeWidth and shapeHeight properties.

Legend padding

You can control the spacing between the legend items using the padding option of the legend. The default value of padding is 5.

Legend border

You can customize the legend border using the border option in the legend. The legend border can be customized using the border color and width properties.

Font of the legend text

The font of the legend item text can be customized using the following properties:

fontFamily
fontStyle
fontWeight 
opacity
color 
size

The following code example shows how to add legend in the gauge.

index.ts
index.html
import { CircularGauge, Legend } from '@syncfusion/ej2-circulargauge';
CircularGauge.Inject(Legend);
let gauge: CircularGauge = new CircularGauge({
    axes: [{
        minimum: 0,
        maximum: 100,
        majorTicks: {
            useRangeColor: true
        },
        minorTicks: {
            useRangeColor: true
        },
        labelStyle: {
            useRangeColor: true
        },

        ranges: [{
            start: 0,
            end: 25,
            radius: '108%'
        },{
            start: 25,
            end: 50,
            radius: '108%'
        },{
            start: 50,
            end: 75,
            radius: '108%'
        },{
            start: 75,
            end: 100,
            radius: '108%'
        }]
    }],
     legendSettings : {
        visible: true,
        shapeWidth:30,
        shapeHeight:30,
        padding:15,
        border: {
            color:'green',
            width:3
        }
    }
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/27.2.2/ej2-popups/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>Loading....</div>
    <div id='container'>
        <div id='element'></div>
    </div>
</body>

</html>

Toggle option in legend

The toggle option has been provided for legend. So, if you toggle the legend, the given color will be changed to the corresponding circular gauge range. You can enable the toggle option using toggleVisibility in the legendSettings property.

index.ts
index.html
import { CircularGauge, Legend } from '@syncfusion/ej2-circulargauge';
CircularGauge.Inject(Legend);
let gauge: CircularGauge = new CircularGauge({
    axes: [{
        minimum: 0,
        maximum: 100,
        majorTicks: {
            useRangeColor: true
        },
        minorTicks: {
            useRangeColor: true
        },
        labelStyle: {
            useRangeColor: true
        },
        ranges: [{
            start: 0,
            end: 25,
            radius: '108%'
        },{
            start: 25,
            end: 50,
            radius: '108%'
        },{
            start: 50,
            end: 75,
            radius: '108%'
        },{
            start: 75,
            end: 100,
            radius: '108%'
        }]
    }],
    legendSettings : {
        visible: true,
        toggleVisibility: true
    }
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/27.2.2/ej2-popups/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>Loading....</div>
    <div id='container'>
        <div id='element'></div>
    </div>
</body>

</html>

Paging support in legend

By default, paging will be enabled if the legend items exceed the legend bounds. You can view each legend item by navigating between the pages using navigation buttons.

index.ts
index.html
import { CircularGauge, Legend } from '@syncfusion/ej2-circulargauge';
CircularGauge.Inject(Legend);
let gauge: CircularGauge = new CircularGauge({
    axes: [{
        minimum: 0,
        maximum: 100,
        majorTicks: {
            useRangeColor: true
        },
        minorTicks: {
            useRangeColor: true
        },
        labelStyle: {
        useRangeColor: true
        },
        ranges: [{
            start: 0,
            end: 25,
            radius: '108%'
        },{
            start: 25,
            end: 50,
            radius: '108%'
        },{
            start: 50,
            end: 75,
            radius: '108%'
        },{
            start: 75,
            end: 100,
          radius: '108%'
        }]
    }],
    legendSettings : {
        visible: true,
        height: '50'
    }
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/27.2.2/ej2-popups/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>Loading....</div>
    <div id='container'>
        <div id='element'></div>
    </div>
</body>

</html>

Legend text customization

You can customize the legend text using legendText property in ranges.

index.ts
index.html
import { CircularGauge, Legend, ILegendRenderEventArgs } from '@syncfusion/ej2-circulargauge';
CircularGauge.Inject(Legend);
let gauge: CircularGauge = new CircularGauge({
    axes: [{
        minimum: 0,
        maximum: 100,
        majorTicks: {
            useRangeColor: true
        },
        minorTicks: {
            useRangeColor: true
        },
        labelStyle: {
            useRangeColor: true
        },
        ranges: [{
            start: 0,
            end: 25,
            radius: '108%',
            legendText: 'light air'
        },{
            start: 25,
            end: 50,
            radius: '108%',
            legendText: 'light air'
        },{
            start: 50,
            end: 75,
            radius: '108%',
            legendText: 'light breeze'

        },{
            start: 75,
            end: 100,
            radius: '108%',
            legendText: 'Gentle breeze'
        }]
    }],
    legendSettings : {
        visible: true
    },
    legendRender: (args: ILegendRenderEventArgs) => {
        args.text = "Legend Modified Text Value";
    }
}, '#element');
<!DOCTYPE html>
<html lang="en">

<head>
    <title>EJ2 Animation</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/ej2/27.2.2/ej2-popups/styles/material.css" rel="stylesheet" />
    <script src="https://cdnjs.cloudflare.com/ajax/libs/systemjs/0.19.38/system.js"></script>
    <script src="systemjs.config.js"></script>
<script src="https://cdn.syncfusion.com/ej2/syncfusion-helper.js" type ="text/javascript"></script>
</head>

<body>
    <div id='loader'>Loading....</div>
    <div id='container'>
        <div id='element'></div>
    </div>
</body>

</html>

legendRendering event will be triggered before rendering each legend item, using this event you can customize needed legend items using following arguments.

Argument name	Description
fill	Specifies the legend shape color
text	Specifies the current legend text
shape	Customize the shape of the legends
name	Specifies the name of the event
cancel	Set to true, to cancel the event status