New to Telerik UI for ASP.NET AJAX? Download free 30-day trial


The client-side ImageExporting event is raised when RadClientExportManager is about to export an image. You can handle this event in case you want to prevent the export. This article shows how to use this event in order to send the file content to the server, save it there and cancel the further execution of the export (See Example 1). For your reference you can find the API controller implementation as well (See Example 2).

To handle this event, simply write a JavaScript function that can be called when the event occurs. Then assign the name of this function as the value of the OnClientImageExporting property.

The client-side ImageExporting event handler receives two arguments:

  1. Sender—the RadClientExportManager object that fired the event.

  2. Event arguments—a ClientExportManagerImageExportingEventArgs object that exposes the following methods:

ClientExportManagerImageExportingEventArgs Object

Name Parameters Return Type Description
get_cancel() bool Gets a value that indicates whether the event is canceled.
get_dataURI() String Returns the image dataURI.
set_cancel(value) bool Sets whether the event will be canceled (if true is passed).

Example 1: Send an image to the server and prevent the client-side export.

<telerik:RadClientExportManager runat="server" ID="RadClientExportManager1" OnClientImageExporting="OnClientImageExporting">
    <ImageSettings FileName="MyFile.png" />

<input type="button" onclick="exportElement()" value="export" />

var $ = $telerik.$;

function OnClientImageExporting(sender, args) {
    var dataRaw = args.get_dataURI().split(',');

    var data = {
        contentType: dataRaw[0].split(';')[0].split(':')[1],
        fileName: "test 1.png",
        base64: dataRaw[1]

        type: "POST",
        data: data,
        url: "api/export/file",
        success: success


function success() {
    $find("<%= FileExplorer1.ClientID %>").refresh();

function exportElement() {
    var exportMngr = $find("<%= RadClientExportManager1.ClientID %>");

Example 2: Save the image sent from the client to a folder on the server.

public class ExportController : ApiController
    public HttpResponseMessage File(FormDataCollection values)
        var contentType = values.Get("contentType");
        var base64 = values.Get("base64");
        var fileName = values.Get("fileName");

        var fileContents = Convert.FromBase64String(base64);

        System.IO.File.WriteAllBytes(System.Web.Hosting.HostingEnvironment.MapPath("~/files") + "\\" + Guid.NewGuid() + "_" + fileName, Convert.FromBase64String(base64));

        var response = new HttpResponseMessage();
        response.StatusCode = HttpStatusCode.OK;

        return response;
Public Class ExportController
    Inherits ApiController
    <HttpPost> _
    Public Function File(values As FormDataCollection) As HttpResponseMessage
        Dim contentType = values.[Get]("contentType")
        Dim base64 = values.[Get]("base64")
        Dim fileName = values.[Get]("fileName")

        Dim fileContents = Convert.FromBase64String(base64)

        System.IO.File.WriteAllBytes(System.Web.Hosting.HostingEnvironment.MapPath("~/files") + "\" + Guid.NewGuid().ToString() + "_" + fileName, Convert.FromBase64String(base64))

        Dim response = New HttpResponseMessage()
        response.StatusCode = HttpStatusCode.OK

        Return response
    End Function
End Class
#End Region

See Also

In this article