/// <summary>
/// Enables processing of HTTP Web requests by a custom HttpHandler that implements the <see cref="T:System.Web.IHttpHandler"/> interface.
/// </summary>
/// <param name="context">An <see cref="T:System.Web.HttpContext"/> object that provides references to the intrinsic server objects (for example, Request, Response, Session, and Server) used to service HTTP requests.</param>
public void ProcessRequest(HttpContext context)
{
// get the unique GUID of the captcha; this must be passed in via the querystring
String guid = context.Request.QueryString["guid"];
CaptchaImage ci = CaptchaImage.GetCachedCaptcha(guid);
if (String.IsNullOrEmpty(guid) || ci == null)
{
context.Response.StatusCode = 404;
context.Response.StatusDescription = "Not Found";
context.ApplicationInstance.CompleteRequest();
return;
}
// write the image to the HTTP output stream as an array of bytes
using (Bitmap b = ci.RenderImage())
{
b.Save(context.Response.OutputStream, ImageFormat.Gif);
}
context.Response.ContentType = "image/png";
context.Response.StatusCode = 200;
context.Response.StatusDescription = "OK";
context.ApplicationInstance.CompleteRequest();
}
/// <summary>
/// Generates the captcha image.
/// </summary>
/// <param name="helper">The helper.</param>
/// <param name="height">The height.</param>
/// <param name="width">The width.</param>
/// <returns>
/// Returns the <see cref="Uri"/> for the generated <see cref="CaptchaImage"/>.
/// </returns>
public static String CaptchaImage(this HtmlHelper helper, int height, int width)
{
var image = new CaptchaImage
{
Height = height,
Width = width,
};
HttpRuntime.Cache.Add(
image.UniqueId,
image,
null,
DateTime.Now.AddSeconds(Captcha.CaptchaImage.CacheTimeOut),
Cache.NoSlidingExpiration,
CacheItemPriority.NotRemovable,
null);
var stringBuilder = new StringBuilder(256);
stringBuilder.Append("<input type=\"hidden\" name=\"captcha-guid\" value=\"");
stringBuilder.Append(image.UniqueId);
stringBuilder.Append("\" />");
stringBuilder.AppendLine();
stringBuilder.Append("<img src=\"");
stringBuilder.Append(ApplicationUtility.Path + "captcha.ashx?guid=" + image.UniqueId);
stringBuilder.Append("\" alt=\"CAPTCHA\" width=\"");
stringBuilder.Append(width);
stringBuilder.Append("\" height=\"");
stringBuilder.Append(height);
stringBuilder.Append("\" />");
return stringBuilder.ToString();
}
