Virtual scrolling in Angular Schedule component
11 Jul 202418 minutes to read
To achieve better performance in the Scheduler when loading a large number of resources and events, we have added virtual scrolling support in the timeline views to load a large set of resources and events instantly as you scroll. You can dynamically load large number of resources and events in timeline view of the Scheduler by setting true to the allowVirtualScrolling property within the timeline view-specific settings. The virtual loading of events is possible in Agenda view, by setting allowVirtualScrolling property to true within the agenda view specific settings.
import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ScheduleModule } from '@syncfusion/ej2-angular-schedule'
import { ButtonModule } from '@syncfusion/ej2-angular-buttons'
import { DayService, WeekService, WorkWeekService, MonthService, AgendaService, MonthAgendaService} from '@syncfusion/ej2-angular-schedule'
import { Component } from '@angular/core';
import { EventSettingsModel, TimelineMonthService, TimelineYearService, GroupModel } from '@syncfusion/ej2-angular-schedule';
@Component({
imports: [
ScheduleModule,
ButtonModule
],
providers: [DayService,
WeekService,
WorkWeekService,
MonthService,
AgendaService,
MonthAgendaService,
TimelineMonthService, TimelineYearService],
standalone: true,
selector: 'app-root',
// specifies the template string for the Schedule component
template: `<ejs-schedule width='100%' cssClass='virtual-scrolling' height='550px' [group]="group" [selectedDate]="selectedDate" [eventSettings]="eventSettings">
<e-resources>
<e-resource field='ResourceId' title='Resource' [dataSource]='resourceDataSource' [allowMultiple]='allowMultiple'
name='Resources' textField='Text' idField='Id' colorField='Color'>
</e-resource>
</e-resources>
<e-views>
<e-view option="TimelineMonth" [allowVirtualScrolling]="virtualscroll" isSelected=true></e-view>
<e-view option="TimelineYear" [allowVirtualScrolling]="virtualscroll" orientation="Vertical"></e-view>
</e-views>
</ejs-schedule>`
})
export class AppComponent {
public selectedDate: Date = new Date(2018, 4, 1);
public group: GroupModel = { byGroupID: false, resources: ['Resources'] };
public allowMultiple: boolean = true;
public resourceDataSource: Object[] = this.generateResourceData(1, 300, 'Resource');
public eventSettings: EventSettingsModel = { dataSource: this.generateStaticEvents(new Date(2018, 4, 1), 300, 12) };
public virtualscroll: boolean = true;
private generateStaticEvents(start: Date, resCount: number, overlapCount: number): Object[] {
let data: Object[] = [];
let id: number = 1;
for (let i: number = 0; i < resCount; i++) {
let randomCollection: number[] = [];
let random: number = 0;
for (let j: number = 0; j < overlapCount; j++) {
random = Math.floor(Math.random() * (30));
random = (random === 0) ? 1 : random;
if (randomCollection.indexOf(random) !== -1 || randomCollection.indexOf(random + 2) !== -1 ||
randomCollection.indexOf(random - 2) !== -1) {
random += (Math.max.apply(null, randomCollection) + 10);
}
for (let k: number = 1; k <= 2; k++) {
randomCollection.push(random + k);
}
let startDate: Date = new Date(start.getFullYear(), start.getMonth(), random);
startDate = new Date(startDate.getTime() + (((random % 10) * 10) * (1000 * 60)));
let endDate: Date = new Date(startDate.getTime() + ((1440 + 30) * (1000 * 60)));
data.push({
Id: id,
Subject: 'Event #' + id,
StartTime: startDate,
EndTime: endDate,
IsAllDay: (id % 10) ? false : true,
ResourceId: i + 1
});
id++;
}
}
return data;
};
private generateResourceData(startId: number, endId: number, text: string): Object[] {
let data: { [key: string]: Object }[] = [];
let colors: string[] = [
'#ff8787', '#9775fa', '#748ffc', '#3bc9db', '#69db7c',
'#fdd835', '#748ffc', '#9775fa', '#df5286', '#7fa900',
'#fec200', '#5978ee', '#00bdae', '#ea80fc'
];
for (let a: number = startId; a <= endId; a++) {
let n: number = Math.floor(Math.random() * colors.length);
data.push({
Id: a,
Text: text + ' ' + a,
Color: colors[n]
});
}
return data;
}
}import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));
For now, the virtual loading of resources and events is available only
TimelineDay,TimelineWeek,TimelineWorkWeek,TimelineMonthandTimelineYear(Vertical Orientation alone) views. In the future, we plan to port the same virtual loading on all other applicable Scheduler views.
Enabling lazy loading for appointments
The lazy loading feature provides a convenient way to efficiently load resource appointments into the Scheduler using an on-demand approach. With this feature, you can seamlessly load a large volume of appointment data into the Scheduler without experiencing any performance degradation.
By default, the Scheduler fetches all the relevant appointments from the server with in the current date range. However, enabling this feature will trigger query requests to the server for appointment retrieval whenever new resources are rendered due to scroll actions. These queries contain the resource IDs of currently displayed resources along with current date range, which can be passed as a comma-separated string. In the server controller, these resource IDs are parsed to filter the necessary appointments to render in the scheduler.
When you enable this feature, the Scheduler becomes capable of fetching events from remote services only for the current view port alone to optimize the data retrieval. The remaining appointment data is fetched form the server on-demand based on currently rendered view port resources as you scroll’s through the scheduler content.
To enable this feature, you have to set the enableLazyLoading property to true within the view specific settings.
import { NgModule } from '@angular/core'
import { BrowserModule } from '@angular/platform-browser'
import { ScheduleModule, TimelineMonthService, RecurrenceEditorModule } from '@syncfusion/ej2-angular-schedule'
import { ButtonModule } from '@syncfusion/ej2-angular-buttons'
import { Component } from '@angular/core';
import { EventSettingsModel, GroupModel } from '@syncfusion/ej2-angular-schedule';
import { DataManager, WebApiAdaptor } from '@syncfusion/ej2-data';
@Component({
imports: [
ScheduleModule,
RecurrenceEditorModule,
ButtonModule
],
standalone: true,
selector: 'app-root',
providers: [TimelineMonthService],
// specifies the template string for the Schedule component
template: `<ejs-schedule width='100%' height='550px' [readonly]='readonly' [group]="group" [selectedDate]="selectedDate" [eventSettings]="eventSettings">
<e-resources>
<e-resource field='ResourceId' title='Resource' [dataSource]='resourceDataSource'
name='Resources' textField='Text' idField='Id' colorField='Color'>
</e-resource>
</e-resources>
<e-views>
<e-view option="TimelineMonth" [enableLazyLoading]="enableLazyLoad" isSelected=true></e-view>
</e-views>
</ejs-schedule>`
})
export class AppComponent {
public selectedDate: Date = new Date(2023, 3, 1);
public readonly: boolean = true;
public group: GroupModel = { resources: ['Resources'] };
public resourceDataSource: Object[] = this.generateResourceData(1, 1000, 'Resource');
private dataManager: DataManager = new DataManager({
url: 'https://services.syncfusion.com/angular/production/api/VirtualEventData',
adaptor: new WebApiAdaptor(),
crossDomain: true
});
public eventSettings: EventSettingsModel = { dataSource: this.dataManager };
public enableLazyLoad: boolean = true;
private generateResourceData(startId: number, endId: number, text: string): Object[] {
let data: { [key: string]: Object }[] = [];
let colors: string[] = [
'#ff8787', '#9775fa', '#748ffc', '#3bc9db', '#69db7c',
'#fdd835', '#748ffc', '#9775fa', '#df5286', '#7fa900',
'#fec200', '#5978ee', '#00bdae', '#ea80fc'
];
for (let a: number = startId; a <= endId; a++) {
let n: number = Math.floor(Math.random() * colors.length);
data.push({
Id: a,
Text: text + ' ' + a,
Color: colors[n]
});
}
return data;
}
}import { bootstrapApplication } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import 'zone.js';
bootstrapApplication(AppComponent).catch((err) => console.error(err));Here’s the server-side controller code that retrieves appointment data based on the resource IDs provided as query parameters:
using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;
using System;
using Microsoft.EntityFrameworkCore;
using System.Linq;
using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.OData.Query;
namespace LazyLoadingServices.Controllers
{
public class VirtualEventDataController : Controller
{
private readonly EventsContext dbContext;
[HttpGet]
[EnableQuery]
[Route("api/VirtualEventData")]
public IActionResult GetData([FromQuery] Params param)
{
IQueryable<EventData> query = dbContext.Events;
// Filter the appointment data based on the ResourceId query params.
if (!string.IsNullOrEmpty(param.ResourceId))
{
string[] resourceId = param.ResourceId.Split(',');
query = query.Where(data => resourceId.Contains(data.ResourceId.ToString()));
}
return Ok(query.ToList());
}
}
public class Params
{
public DateTime? StartDate { get; set; }
public DateTime? EndDate { get; set; }
public string ResourceId { get; set; }
}
}Note:
- The property will be effective, when large number of resources and appointments bound to the Scheduler.
- This property is applicable only when resource grouping is enabled in Scheduler.
See Also
You can refer to our Angular Scheduler feature tour page for its groundbreaking feature representations. You can also explore our Angular Scheduler example to knows how to present and manipulate data.