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POUsing ASP.NET AJAX UpdatePanel with Handlers
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  1. POUsing ASP.NET AJAX UpdatePanel with Handlers
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    copied!<p>Im using UpdatePanel for some controls specially for captchas so, when a AsyncPostBack is performed triggered by a button "btnQuery", How can I tell to the .ashx (Handler for Captcha) to refresh it self?</p> <p>Im using session to validate the Image on Captcha to the Num on the input below the image </p> <p>this is the Handler : </p> <pre><code>&lt;%@ WebHandler Language="C#" Class="captcha" %&gt; using System; using System.Web; using System.Web.SessionState; using System.Drawing; public class captcha : IHttpHandler, IRequiresSessionState { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "image/GIF"; Bitmap imagen_GIF = new System.Drawing.Bitmap(80, 30); Graphics grafico = System.Drawing.Graphics.FromImage(imagen_GIF); grafico.Clear(Color.Gainsboro); Font tipo_fuente = new Font("Comic Sans", 12, FontStyle.Bold); string randomNum = string.Empty; Random autoRand = new Random(); for (int x = 0; x &lt; 5; x++) { randomNum += System.Convert.ToInt32(autoRand.Next(0, 9)).ToString(); } int i_letra = System.Convert.ToInt32(autoRand.Next(65, 90)); string letra = ((char)i_letra).ToString(); randomNum += letra; context.Session["RandomNumero"] = randomNum; grafico.DrawString(randomNum, tipo_fuente, Brushes.Black, 5, 5); imagen_GIF.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Gif); tipo_fuente.Dispose(); grafico.Dispose(); imagen_GIF.Dispose(); } public bool IsReusable { get { return false; } } } </code></pre> <p>I want to refresh the image.. not just doing this : </p> <pre><code> public void postbackear() { string script = string.Format("Sys.WebForms.PageRequestManager.getInstance()._doPostBack('{0}', '');", btnConsulta.ID); ScriptManager.RegisterStartupScript(this.Page, typeof(string), "Refresh", script, true); } </code></pre>
 

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