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Legend in React Maps component

05 Aug 2021 / 8 minutes to read

A legend is a key used on a map that contains swatches of symbols with descriptions. It provides valuable information for interpreting what the map is displaying and can be represented in various colors, shapes or other identifiers based on the data. It gives a breakdown of what each symbol represents throughout the map.

Visibility

The Legends can be made visible by setting the visible property of legendSettings to true.

Positioning the Legend

The legend can be positioned in two ways.

Absolute Position.
Dock Position.

Absolute Position

Based on the margin values of X and Y-axes, the Map legends can be positioned with the support of location.x and location.y properties available in legendSettings. For positioning the legend based on margins corresponding to a map, position value is set as ‘Float’.

Dock Position

The map legends can be positioned in following locations within the container. You can set this option by using position property in legendSettings.

1 Top

2 Left

3 Bottom

4 Right

above four positions can be aligned combination of ‘Near’, ‘Center’ and ‘Far’ using alignment in legendSettings. So legend can be aligned 12 positions.

Legend Mode

Legend had two type of mode. Default mode and Interactive mode.

Default Mode

Default mode legends having symbols with legend labels, used to identify the shape or bubble or marker color.

Interactive Mode

The legends can be made interactive with an arrow mark indicating the exact range color in the legend when the mouse hovers over the corresponding shapes. You can enable this option by setting mode property in legendSettings value as “Interactive” and default value of mode property is “Default” to enable the normal legend.

Legend Size

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

Legend for Shapes

The Layer shape type legends can be generated for each color mappings in shape settings. Note: Below code snippet demonstrate the equal colormapping legends for the shapes.

Create the electiondata.ts file with following data for layer dataSource.

export var UNcountries: Object[] =
[
{  "Country": "China", "Membership": "Permanent"},
        {"Country": "France","Membership": "Permanent" },
        { "Country": "Russia","Membership": "Permanent"},
        {"Country": "Kazakhstan","Membership": "Non-Permanent"},
        { "Country": "Poland","Membership": "Non-Permanent"},
        {"Country": "Sweden","Membership": "Non-Permanent"}
];

export var UNcountries = [
    { "Country": "China", "Membership": "Permanent" },
    { "Country": "France", "Membership": "Permanent" },
    { "Country": "Russia", "Membership": "Permanent" },
    { "Country": "Kazakhstan", "Membership": "Non-Permanent" },
    { "Country": "Poland", "Membership": "Non-Permanent" },
    { "Country": "Sweden", "Membership": "Non-Permanent" }
];

Import the ‘electionData’ and assign for the layer dataSource. Provide the shapePropertyPath value as ‘name and shapeDataPath value as ‘State’.

To enable the equal colormapping refer the shapeSettings.colorMapping code snippet.

Finally set legendSettings.visible as true and Inject the Legend Module into Maps using <Inject services={[Legend]}/> tag.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { uncountries } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true } } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='Country' shapePropertyPath='name' dataSource={uncountries}
                    shapeSettings={ {
                        colorValuePath: 'Membership',
            colorMapping: [
            {
                value: 'Permanent', color: '#D84444'
            },
            {
                value: 'Non-Permanent', color: '#316DB5'
            }]
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { uncountries } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='Country' shapePropertyPath='name' dataSource={uncountries} shapeSettings={{
    colorValuePath: 'Membership',
    colorMapping: [
        {
            value: 'Permanent', color: '#D84444'
        },
        {
            value: 'Non-Permanent', color: '#316DB5'
        }
    ]
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Legend Shape

To get the legend shape value for legendSettings by using shape property. You can customize the shape by using the shapeWidth and shapeHeight property.

Legend for items excluded from color mapping

Based on the ranges in data source, get the excluded ranges from color mapping, and then show the legend with excluded range values are bound to the specific legend.

The following code example shows legends for the items excluded from color mapping.

Finally set legendSettings.visible as true and Inject the Legend Module into Maps using <Inject services={[Legend]}/> tag.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { uncountries } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true } } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='Country' shapePropertyPath='name' dataSource={uncountries}
                    shapeSettings={ {
                        colorValuePath: 'Membership',
                    colorMapping: [
                    {
                        from: 0, to: 100, color: 'rgb(153,174,214)',
                    },
                    {
                        from: 101, to: 200, color: 'rgb(115,143,199)',
                    },
                    {
                        color: 'rgb(77,112,184)'
                    }]
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { uncountries } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='Country' shapePropertyPath='name' dataSource={uncountries} shapeSettings={{
    colorValuePath: 'Membership',
    colorMapping: [
        {
            from: 0, to: 100, color: 'rgb(153,174,214)',
        },
        {
            from: 101, to: 200, color: 'rgb(115,143,199)',
        },
        {
            color: 'rgb(77,112,184)'
        }
    ]
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Hide desired legend items

To enable or disable the desired legend for each colormapping, set the showLegend property to true in colorMapping.

The following code example shows legends for the items excluded from color mapping.

Finally set legendSettings.visible as true and Inject the Legend Module into Maps using <Inject services={[Legend]}/> tag.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { uncountries } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true } } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='Country' shapePropertyPath='name' dataSource={uncountries}
                    shapeSettings={ {
                        colorValuePath: 'Membership',
                    colorMapping: [
                    {
                        from: 0, to: 100, color: 'rgb(153,174,214)',
                        showLegend: true
                    },
                    {
                        from: 101, to: 200, color: 'rgb(115,143,199)',
                        showLegend: false
                    },
                    {
                        color: 'rgb(77,112,184)', showLegend: false
                    }]
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { uncountries } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='Country' shapePropertyPath='name' dataSource={uncountries} shapeSettings={{
    colorValuePath: 'Membership',
    colorMapping: [
        {
            from: 0, to: 100, color: 'rgb(153,174,214)',
            showLegend: true
        },
        {
            from: 101, to: 200, color: 'rgb(115,143,199)',
            showLegend: false
        },
        {
            color: 'rgb(77,112,184)', showLegend: false
        }
    ]
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Hide legend items based data source value

To enable or disable the legend visibility for each item, bind the field name in the data source to the showLegendPath property in legendSettings.

The following code example shows how to hide the legend items based data source value.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { dafaultData } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true , showLegendPath: 'visibility'} } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='continent' shapePropertyPath='continent' dataSource={dafaultData}
                    shapeSettings={ {
                        colorValuePath: 'color',
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { dafaultData } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true, showLegendPath: 'visibility' }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='continent' shapePropertyPath='continent' dataSource={dafaultData} shapeSettings={{
    colorValuePath: 'color',
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Bind legend item text from data source

To show the legend text based on binding, the field name in the datasource should be set to the valuePath property in legendSettings.

The following code example shows how to hide the legend items based data source value.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { dafaultData } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true , valuePath: 'continent'} } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='continent' shapePropertyPath='continent' dataSource={dafaultData}
                    shapeSettings={ {
                        colorValuePath: 'color',
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { dafaultData } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true, valuePath: 'continent' }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='continent' shapePropertyPath='continent' dataSource={dafaultData} shapeSettings={{
    colorValuePath: 'color',
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Hide duplicate legend items

To show the legend text based on binding, the field name in the datasource should be set to the valuePath property in legendSettings.

The following code example shows how to hide the legend items based data source value.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { dafaultData } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true , valuePath: 'continent' ,
        removeDuplicateLegend: true} } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='continent' shapePropertyPath='continent' dataSource={dafaultData}
                    shapeSettings={ {
                        colorValuePath: 'color',
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { dafaultData } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true, valuePath: 'continent',
    removeDuplicateLegend: true }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='continent' shapePropertyPath='continent' dataSource={dafaultData} shapeSettings={{
    colorValuePath: 'color',
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Toggle option in legend

The toggle option has been provided for legend. So, if you toggle a legend, the given color will be changed to the corresponding maps shape item. You can enable the toggle options using the toggleLegendSettings property.

The following options are available to customize the shape of the map:

applyShapeSettings – Applies the fill property value in shapeSettings to a shape of the maps if it is true and a legend item is clicked.
fill- Specifies the color to the shape of the maps.
opacity – Specifies the transparency of the legend.
border – Specifies the border color and width.

Source

Preview

index.tsx

index.jsx

import { world_map } from 'world-map.ts';
import { population_density } from 'data.ts'
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';

ReactDOM.render(
        <MapsComponent id="maps" legendSettings={ { visible: true, toggleLegendSettings: { enable: true } } } >
        <Inject services={[Legend]} />
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='name' shapePropertyPath='name'
                    dataSource={population_density}
                    shapeSettings={ {
                        colorValuePath: 'density',
                        colorMapping: [
                            {
                                from: 0, to: 100, color: 'rgb(153,174,214)',
                            },
                            {
                                from: 101, to: 200, color: 'rgb(115,143,199)',
                            },
                            {
                                color: 'rgb(77,112,184)'
                            }
                        ]
                    } }>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>,
document.getElementById("maps") as HTMLElement
);

import { world_map } from 'world-map.ts';
import { population_density } from 'data.ts';
import * as React from "react";
import * as ReactDOM from "react-dom";
import { MapsComponent, LayersDirective, LayerDirective, Inject, Legend } from '@syncfusion/ej2-react-maps';
ReactDOM.render(<MapsComponent id="maps" legendSettings={{ visible: true, toggleLegendSettings: { enable: true } }}>
        <Inject services={[Legend]}/>
            <LayersDirective>
                <LayerDirective shapeData={world_map} shapeDataPath='name' shapePropertyPath='name' dataSource={population_density} shapeSettings={{
    colorValuePath: 'density',
    colorMapping: [
        {
            from: 0, to: 100, color: 'rgb(153,174,214)',
        },
        {
            from: 101, to: 200, color: 'rgb(115,143,199)',
        },
        {
            color: 'rgb(77,112,184)'
        }
    ]
}}>
                </LayerDirective>
            </LayersDirective>
        </MapsComponent>, document.getElementById("maps"));

Refer the API for Legend feature.

Contents

Visibility
Positioning the Legend
Absolute Position
Dock Position
Legend Mode
Default Mode
Interactive Mode
Legend Size
Legend for Shapes
Legend Shape
Legend for items excluded from color mapping
Hide desired legend items
Hide legend items based data source value
Bind legend item text from data source
Hide duplicate legend items
Toggle option in legend

Contents

Visibility
Positioning the Legend
Absolute Position
Dock Position
Legend Mode
Default Mode
Interactive Mode
Legend Size
Legend for Shapes
Legend Shape
Legend for items excluded from color mapping
Hide desired legend items
Hide legend items based data source value
Bind legend item text from data source
Hide duplicate legend items
Toggle option in legend