Chart annotations in Angular Chart component

10 Oct 202517 minutes to read

Annotations are used to mark the specific area of interest in the chart area with texts, shapes or images.

You can add annotations to the chart by using the annotations option. By using the
content option of annotation object, you can specify
the id of the element that needs to be displayed in the chart area.

To known more about annotations, you can check on this video:

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ChartModule } from '@syncfusion/ej2-angular-charts'
import { CategoryService, DateTimeService, ScrollBarService, ColumnSeriesService, LineSeriesService, 
    ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService,LegendService, TooltipService
 } from '@syncfusion/ej2-angular-charts'



import { Component, OnInit } from '@angular/core';
@Component({
imports: [
         ChartModule
    ],

providers: [ CategoryService, DateTimeService, ScrollBarService, LineSeriesService, ColumnSeriesService, 
        ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService, LegendService, TooltipService,],
standalone: true,
    selector: 'app-container',
    template: `<ejs-chart id="chart-container" [primaryXAxis]='primaryXAxis'[primaryYAxis]='primaryYAxis' [title]='title'>
        <e-annotations>
            <e-annotation  content='70 Gold Medals' region='Series' coordinateUnits='Point' x='Japan' y=75>
            </e-annotation>
        </e-annotations>
        <e-series-collection>
            <e-series [dataSource]='chartData' type='Column' xName='country' yName='gold' name='Gold'></e-series>
        </e-series-collection>
    </ejs-chart>`
})
export class AppComponent implements OnInit {
    public primaryXAxis?: Object;
    public chartData?: Object[];
    public title?: string;
    public primaryYAxis?: Object;
    ngOnInit(): void {
        this.chartData = [
             { country: "USA", gold: 50 },
             { country: "China", gold: 40 },
             { country: "Japan", gold: 70 },
             { country: "Australia", gold: 60 },
             { country: "France", gold: 50 },
             { country: "Germany", gold: 40 },
             { country: "Italy", gold: 40 },
             { country: "Sweden", gold: 30 }
        ];
        this.primaryXAxis = {
           valueType: 'Category',
           title: 'Countries'
        };
        this.primaryYAxis = {
            minimum: 0, maximum: 80,
            interval: 20, title: 'Medals'
        };
        this.title = 'Olympic Medals';
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

Note: To use annotation feature in chart, we need to inject ChartAnnotationService into the @NgModule.providers.

Region

Annotations can be placed either with respect to Series or Chart. by default, it will placed with respect to Chart.

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ChartModule } from '@syncfusion/ej2-angular-charts'
import { CategoryService, DateTimeService, ScrollBarService, ColumnSeriesService, LineSeriesService, 
    ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService,LegendService, TooltipService
 } from '@syncfusion/ej2-angular-charts'



import { Component, OnInit } from '@angular/core';
import { columnData } from './datasource';
@Component({
imports: [
         ChartModule
    ],

providers: [ CategoryService, DateTimeService, ScrollBarService, LineSeriesService, ColumnSeriesService, 
        ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService, LegendService, TooltipService,],
standalone: true,
    selector: 'app-container',
    template: `<ejs-chart id="chart-container" [primaryXAxis]='primaryXAxis'[primaryYAxis]='primaryYAxis' [title]='title'>
        <e-annotations>
            <e-annotation  content='<div>Highest Medal Count</div>' region='Series' coordinateUnits='Point' x='Japan' y=75>
            </e-annotation>
        </e-annotations>
        <e-series-collection>
            <e-series [dataSource]='chartData' type='Column' xName='country' yName='gold' name='Gold'></e-series>
        </e-series-collection>
    </ejs-chart>`
})
export class AppComponent implements OnInit {
    public primaryXAxis?: Object;
    public chartData?: Object[];
    public title?: string;
    public primaryYAxis?: Object;
    ngOnInit(): void {
        this.chartData = columnData;
        this.primaryXAxis = {
           valueType: 'Category',
           title: 'Countries'
        };
        this.primaryYAxis = {
            minimum: 0, maximum: 80,
            interval: 20, title: 'Medals'
        };
        this.title = 'Olympic Medals';
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

Co-ordinate Units

Specified the coordinates units of the annotation either Pixel or Point.

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ChartModule } from '@syncfusion/ej2-angular-charts'
import { CategoryService, DateTimeService, ScrollBarService, ColumnSeriesService, LineSeriesService, 
    ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService,LegendService, TooltipService
 } from '@syncfusion/ej2-angular-charts'



import { Component, OnInit } from '@angular/core';
import { columnData } from './datasource';
@Component({
imports: [
         ChartModule
    ],

providers: [ CategoryService, DateTimeService, ScrollBarService, LineSeriesService, ColumnSeriesService, 
        ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService, LegendService, TooltipService,],
standalone: true,
    selector: 'app-container',
    template: `<ejs-chart id="chart-container" [primaryXAxis]='primaryXAxis'[primaryYAxis]='primaryYAxis' [title]='title'>
        <e-annotations>
            <e-annotation  content='<div style="border: 1px solid black; padidng: 5px 5px 5px 5px, backgrund:#f5f5f5">Annotation in Pixel</div>'
             coordinateUnits='Pixel' x=150 y=75>
            </e-annotation>
        </e-annotations>
        <e-series-collection>
            <e-series [dataSource]='chartData' type='Column' xName='country' yName='gold' name='Gold'></e-series>
        </e-series-collection>
    </ejs-chart>`
})
export class AppComponent implements OnInit {
    public primaryXAxis?: Object;
    public chartData?: Object[];
    public title?: string;
    public primaryYAxis?: Object;
    ngOnInit(): void {
        this.chartData = columnData;
        this.primaryXAxis = {
           valueType: 'Category',
           title: 'Countries'
        };
        this.primaryYAxis = {
            minimum: 0, maximum: 80,
            interval: 20, title: 'Medals'
        };
        this.title = 'Olympic Medals';
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

Alignment

Annotation provides verticalAlignment and horizontalAlignment. The verticalAlignment can be customized via Top, Bottom or Middle and the horizontalAlignment can be customized via Near, Far or Center.

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ChartModule } from '@syncfusion/ej2-angular-charts'
import { CategoryService, DateTimeService, ScrollBarService, ColumnSeriesService, LineSeriesService, 
    ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService,LegendService, TooltipService
 } from '@syncfusion/ej2-angular-charts'



import { Component, OnInit } from '@angular/core';
import { columnData } from './datasource';
@Component({
imports: [
         ChartModule
    ],

providers: [ CategoryService, DateTimeService, ScrollBarService, LineSeriesService, ColumnSeriesService, 
        ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService, LegendService, TooltipService,],
standalone: true,
    selector: 'app-container',
    template: `<ejs-chart id="chart-container" [primaryXAxis]='primaryXAxis'[primaryYAxis]='primaryYAxis' [title]='title'>
        <e-annotations>
            <e-annotation  content='<div style="border: 1px solid black; padidng: 5px 5px 5px 5px, backgrund:#f5f5f5">Highest Medal Count</div>'
           verticalAlignment='Top' horizontalAlignment='Near' x='France' y=50>
            </e-annotation>
        </e-annotations>
        <e-series-collection>
            <e-series [dataSource]='chartData' type='Column' xName='country' yName='gold' name='Gold'></e-series>
        </e-series-collection>
    </ejs-chart>`
})
export class AppComponent implements OnInit {
    public primaryXAxis?: Object;
    public chartData?: Object[];
    public title?: string;
    public primaryYAxis?: Object;
    public border?: Object;
    public margin?: Object;
    ngOnInit(): void {
        this.chartData = columnData;
        this.primaryXAxis = {
           valueType: 'Category',
           title: 'Countries'
        };
        this.primaryYAxis = {
            minimum: 0, maximum: 80,
            interval: 20, title: 'Medals'
        };
        this.title = 'Olympic Medals';
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

Adding y-axis sub title through on annotation

By setting text div in the content option of annotation object you can add sub title to chart y-axis. Specified the coordinate value as pixel and customize x and y location of the text.

import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ChartModule } from '@syncfusion/ej2-angular-charts'
import { CategoryService, DateTimeService, ScrollBarService, ColumnSeriesService, LineSeriesService, 
    ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService,LegendService, TooltipService
 } from '@syncfusion/ej2-angular-charts'



import { Component, OnInit } from '@angular/core';
import { columnData } from './datasource';
@Component({
imports: [
         ChartModule
    ],

providers: [ CategoryService, DateTimeService, ScrollBarService, LineSeriesService, ColumnSeriesService, 
        ChartAnnotationService, RangeColumnSeriesService, StackingColumnSeriesService, LegendService, TooltipService,],
standalone: true,
    selector: 'app-container',
    template: `<ejs-chart id="chart-container" [primaryXAxis]='primaryXAxis'[primaryYAxis]='primaryYAxis' [title]='title'>
        <e-annotations>
            <e-annotation content='<div id="text" style="transform: rotate(-90deg);">Speed</div>'
           verticalAlignment='Top' horizontalAlignment='Near' x=18 y=180 coordinateUnits='Pixel'>
            </e-annotation>
        </e-annotations>
        <e-series-collection>
            <e-series [dataSource]='chartData' type='Column' xName='country' yName='gold' name='Gold'></e-series>
        </e-series-collection>
    </ejs-chart>
    <style></style>`
})
export class AppComponent implements OnInit {
    public primaryXAxis?: Object;
    public chartData?: Object[];
    public title?: string;
    public primaryYAxis?: Object;
    public border?: Object;
    public margin?: Object;
    ngOnInit(): void {
        this.chartData = columnData;
        this.primaryXAxis = {
           valueType: 'Category',
           title: 'Countries'
        };
        this.primaryYAxis = {
            minimum: 0, maximum: 80,
            interval: 20, title: 'm3/min'
        };
        this.title = 'Olympic Medals';
    }

}
import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));

See Also