Generate a 1x1 white gif as a Stream in c#

Question

I would like to return an image as an ActionResult from an MVC2 controller. This image is a 1x1 white pixel (for a tracking application). I do not want to reference an image on the disk or in a database. I would like to generate the image in my method and then return it from the controller action.

Any one know how to generate a 1x1 white image that can be passed into a FileStreamResult for returning from the controller action?

Answer 1

Copied from Daniel Ballinger's FishOfPrey.com:

Response.Clear();  
string content = @"R0lGODlhAQABAPcAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAEAAP8ALAAAAAABAAEAAAgEAP8FBAA7";  
Response.ContentType = "image/gif";  
Response.BinaryWrite(System.Convert.FromBase64String(content));  
Response.End();

I don't speak C#, but if you use this string in your program, you can save storing and accessing one extra file on disk.

Answer 2

Avoid the use of Response.End();, as used in eumiro's answer, is not a good idea, read more here: http://support2.microsoft.com/kb/312629

Insted, to avoid unnecessary ThreadAbortException, change your Action to a FileContentResult like this:

public FileContentResult Track(Guid id)
{
    //do tracking stuff ....

    //return empty gif
    const string clearGif1X1 = "R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==";
    return new FileContentResult(
                       Convert.FromBase64String(clearGif1X1), "image/gif");
}

also for tracking purposes remember to add some kind of NoCache attribute