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WebDocumentViewerClientSideEventsBuilderBase<TBuilder, TEvents>.BeforeRender(String) Method
Specifies the JavaScript function that handles the client-side BeforeRender event.
Namespace : DevExpress.AspNetCore.Reporting.WebDocumentViewer
Assembly :
DevExpress.AspNetCore.Reporting.v24.2.dll
NuGet Package :
DevExpress.AspNetCore.Reporting
# Declaration
public TBuilder BeforeRender (
string callback
)
Public Function BeforeRender(
callback As String
) As TBuilder
# Parameters
Name
Type
Description
callback
String
The name of a JavaScript function or entire JavaScript function code that runs when the BeforeRender event occurs.
# Returns
Handle the BeforeRender
event to customize the View Model before it is bound to an HTML element and/or before Knockout binding is activated .
The handler function receives two parameters. The first parameter is the object that exposes the IPreviewModel interface (or the JSReportViewer object). The second is the Document Viewer model that allows you to adjust control settings.
The following code snippet sets the zoom level to 25%, enables multi-page mode, and indicates the moment when the first page is loaded:
<div id ="loader" > <div id ="loaderText" > </div > </div >
<script type ="text/javascript" id ="script" >
function onBeforeRender (s, e ) {
e.reportPreview.zoom = 0.25 ;
e.reportPreview.showMultipagePreview = true ;
$("#loaderText" ).text("Waiting for the first page.." );
e.reportPreview.events.on('propertyChanged' , (args) => {
if (args.propertyName === 'pages' ) {
const newValue = args.newValue;
if (newValue.length > 0 ) {
$("#loaderText" ).text("" );
}
}
});
}
</script >
@{
var viewerRender = Html.DevExpress().WebDocumentViewer("DocumentViewer")
.Height("1000px")
.ClientSideEvents(configure => configure.BeforeRender("onBeforeRender"))
.Bind("TestReport");
@viewerRender.RenderHtml()
}
report-viewer.html
<div >
<dx-report-viewer [reportUrl ]="reportUrl" height ="800px" >
<dxrv-request-options [invokeAction ]="invokeAction" [host ]="hostUrl" >
</dxrv-request-options >
<dxrv-callbacks (BeforeRender )="onBeforeRender($event)" >
</dxrv-callbacks >
</dx-report-viewer >
</div >
report-viewer.ts
import { Component, Inject, ViewEncapsulation, ViewChild } from '@angular/core' ;
import { DxReportViewerComponent } from 'devexpress-reporting-angular' ;
@Component ({
selector: 'report-viewer' ,
encapsulation: ViewEncapsulation.None,
templateUrl: './report-viewer.html' ,
styleUrls: [
"../../../node_modules/devextreme-dist/css/dx.light.css" ,
"../../../node_modules/@devexpress/analytics-core/dist/css/dx-analytics.common.css" ,
"../../../node_modules/@devexpress/analytics-core/dist/css/dx-analytics.light.css" ,
"../../../node_modules/devexpress-reporting/dist/css/dx-webdocumentviewer.css"
]
})
export class ReportViewerComponent {
@ViewChild (DxReportViewerComponent, { static : false }) viewer: DxReportViewerComponent;
reportUrl: string = "TestReport" ;
invokeAction: string = '/DXXRDV' ;
onBeforeRender(event) {
event.args.reportPreview.zoom = 0.25 ;
event.args.reportPreview.showMultipagePreview = true ;
alert("Page load starts..." );
var pages = event.args.reportPreview.pages;
var pagesSubscriptionDispose = event.args.reportPreview.events.on('propertyChanged' , (args ) => {
if (args.propertyName === 'pages' ) {
if (args.newValue.length > 0 ) {
alert("First page is loaded." );
pagesSubscriptionDispose();
}
}
});
}
constructor (@Inject ('BASE_URL' ) public hostUrl: string ) { }
}
'use client' ;
import ReportViewer, { Callbacks, DxReportViewerRef, RequestOptions } from 'devexpress-reporting-react/dx-report-viewer' ;
function App ( ) {
const onBeforeRender = ({ args }): void => {
args.reportPreview.zoom = 0.25 ;
args.reportPreview.showMultipagePreview = true ;
console .log("Page load starts..." );
args.reportPreview.events.on('propertyChanged' , (e ) => {
if (e.propertyName === 'pages' ) {
const newValue = e.newValue;
if (newValue.length > 0 ) {
console .log("A page is loaded. Pages.count: " + newValue.length);
}
}
});
}
return (
<>
<ReportViewer reportUrl="TestExportReport" >
<RequestOptions host="http://localhost:5000/" invokeAction="/DXXRDV" />
<Callbacks BeforeRender={onBeforeRender} />
</ReportViewer>
</ >
)
}
export default App
<template>
<div ref ="viewer" style ="position: absolute; left: 0; right: 0; top: 0; bottom: 0" > </div >
</template>
<script>
import 'devexpress-reporting/ dx-webdocumentviewer';
import { DxReportViewer } from ' devexpress-reporting/dx-webdocumentviewer';
import * as ko from ' knockout';
export default {
name: "WebDocumentViewer",
mounted() {
const reportUrl = ko.observable("TestReport");
const viewerRef = this.$refs.viewer;
const requestOptions = {
host: "https://localhost:5001/",
invokeAction: "DXXRDV"
};
const callbacks = {
BeforeRender: function(s, e){
e.reportPreview.zoom =0.25;
e.reportPreview.showMultipagePreview = true;
alert ("Page load starts...");
//Subscribe to property change.
e.reportPreview.events.on(' propertyChanged', (args) => {
if(args.propertyName === ' pages') {
const newValue = args.newValue;
if (newValue.length > 0) {
alert ("First page is loaded.");
}
}
});
}
};
const viewer = new DxReportViewer(viewerRef, { reportUrl, requestOptions, callbacks });
viewer.render();
},
beforeUnmount() {
ko.cleanNode(this.$refs.viewer);
}
};
</script>
See Also