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Chart annotations in Angular Chart component

3 Feb 202618 minutes to read

Chart annotations allow highlighting specific areas of the chart using text, shapes, images, or custom HTML elements. Annotations can be used to emphasize trends, mark thresholds, show custom notes, or display additional information directly inside the chart area.

Annotations are added using the annotations option. Set the content property to reference the element that should be rendered within the chart.

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 the annotation feature, inject ChartAnnotationService into the @NgModule.providers.

Region

Annotations can be positioned relative to either the overall Chart area or a specific Series. When placed relative to the chart, the annotation uses the chart’s coordinate system. When placed relative to a series, the annotation aligns with that series’ data points. By default, annotations are placed with respect to the 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

Use the coordinateUnits property to define how annotation coordinates are interpreted. Choose between:

  • Pixel – The annotation is positioned using fixed pixel values within the chart area.
  • Point – The annotation is positioned based on chart data points (x and y values).
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