Home / Community & Support / Developer Productivity Tools Forums / ASP.NET AJAX > Chart > Rendering Chart from WebService

• Alexander

  Posted on Aug 6, 2010 (permalink)

  Got html from WebServices.
  With these additional settings to chart control:
  

  chert.UseSession =

   

  false;

   

  chert.TempImagesFolder =

   

  "~/TempImages/";

   

  
  
  Having problem getting chart html from WebService. My task it to have it on client side from WS.
  Failed with both of implementations below:
  1.
  

   

   

   

  [WebMethod]

  public string GetChart()

  {

     RadChart chert = new RadChart();

     chert.ID = "olapChart";

    

  string result = string.Empty;

  using (MemoryStream stream = new MemoryStream())

  {

         StreamWriter writer = new StreamWriter(stream);

         HtmlTextWriter htmlWriter = new HtmlTextWriter(writer);

         chert.RenderControl(htmlWriter);

         System.Text.ASCIIEncoding encoding = new System.Text.ASCIIEncoding();

         writer.Flush();

         result = encoding.GetString(stream.ToArray());

   }

  
  Having "Object reference not set to an instance of an object." on call chert.RenderControl(htmlWriter);
  
  2.
  
  

  [WebMethod]

          public string GetChart()

          {

             return GetChartRendered(chert);

          }

    

          private string GetChartRendered(RadChart chert)

          {

              string result = string.Empty;

    

              TempRenderer pageHolder = new TempRenderer();

              HtmlForm tempForm = new HtmlForm();

              tempForm.ID = "TempForm";

              pageHolder.Controls.Add(tempForm);

              tempForm.Controls.Add(new ScriptManager());

              tempForm.Controls.Add(chert);

    

              StringWriter output = new StringWriter();

              HttpContext.Current.Server.Execute(pageHolder, output, false);

    

              result = output.ToString();

              return result;

          }

    

          public partial class TempRenderer : System.Web.UI.Page

          {

          }

  
  Having "Error executing child request for handler 'ChartTest.TempRenderer'" there on Server.Execute.
  
  3. Eventually created just page "chart.aspx" wiht just single chart control decalred
  

  <

   

   

  telerik:RadChart ID="chert" runat="server" Width="500px" Height="290px" EnableViewState="false" SkinsOverrideStyles="false" ></telerik:RadChart>

   

   

   

  
  and trying this in WebMethod:
  

  StringWriter output = new StringWriter();

  HttpContext.Current.Server.Execute("chart.aspx", output, false);

  string result = output.ToString();

  
  Having ex:" Error executing child request for chart.aspx."
  
  As I understand the reason of all these exceptions is ChartImage.axd
  handler.
  
  If somebody can help - please, it's very urgent.
  Thank you.

   

   

  Reply

• Bartholomeo Rocca Master

  Posted on Aug 11, 2010 (permalink)

  Hello Alexander,
  
  I do not think that this would be possible as the chart image is not just a bunch of html but it is actually served by the ChartImage.axd HttpHandler.
  
  You might try saving the chart image to a stream via RadChart.Save(...) method and process the result with your service.
  
  
  Greetings,
  Bart.

  Reply


• kulashaker

  Posted on Jan 31, 2012 (permalink)

  Hi, I know this thread is quite old, but I actually need to run Chart.RenderControl.
  
  Reason is that I need to extract the ImageMap collection from the resulting HTML that RenderControl produces. I know it sounds messy but there is no property that exposes the ImageMap in the RadChart control.
  
  Is there another way of doing this?
  
  Cheers
  Bruce

  Reply

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