FlexCelHtmlImageHandler Class

This is a base image handler you can use to create your own. This code is adapted from here: http://www.hanselman.com/blog/PermaLink,guid,5c59d662-b250-4eb2-96e4-f274295bd52e.aspx We would like to thank Scott Hanselman for the insightful article.

Remarks

To use this handler, include the following lines in a Web.config file. <configuration> <system.web> <httpHandlers> <add verb="*" path="flexcelviewer.ashx" type="FlexCel.AspNet.FlexCelHtmlImageHandler,FlexCel.AspNet"/> </httpHandlers> </system.web> </configuration> You might need to change the name "flexcelviewer.ashx" if you change FlexCelAspViewer.ImageHandlerName. Both names need to be the same.

Syntax

Namespace: FlexCel.AspNet

public class FlexCelHtmlImageHandler: IHttpHandler

Methods

Name	Description
ProcessRequest	This method will validate the parameters, and then call GetImage to get the real data. When inheriting from this class, you normally only have to override ValidateParameters GetImage
ValidateParameters	Override this method to check the parameters are valid.
ImageExists	Override this method to provide a 404 error if the image has been deleted or doesn't exists.
GetImage	Override this method to return the image. WARNING: Whatever you do here, make really sure you return only the indented image. A NAIVE IMPLEMENTATION OF THIS METHOD MIGHT RESULT IN A HUGE SECURITY HOLE. An attacker could use an implementation that just returns a file to retrieve any file in the server.

Properties

Name	Description
IsReusable	This instance can be reused.
RequiresAuthentication	Override this property in a descendant class if you do not want to ask for authentication for this image handler.