Alternatives to System.Drawing for use with ASP.NET?

Question

After several days of tracking down bizarre GDI+ errors, I've stumbled across this little gem on MSDN:

Classes within the System.Drawing namespace are not supported for use within a Windows or ASP.NET service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions.

I don't know whether "ASP.NET service" means "web application" in this context, but "diminished service performance" certainly seems to cover the random assortment of "A generic error occurred in GDI+" and "Out of memory" errors that my app is throwing - intermittent, non-reproducible errors reading and writing JPEG images that - in many cases - were actually created by System.Drawing.Imaging in the first place.

So - if GDI+ can't read and write JPEG files reliably in a Web app, what should I be using instead?

I want users to be able to upload images (JPEG required, other formats nice-to-have), resample them reliably, and display useful error messages if anything goes wrong. Any ideas? Are the System.Media namespaces from WPF worth considering?

Thanks,

Dylan

EDIT: Yeah, I know GDI+ works "most of the time". That's not good enough, because when it fails, it does so in a way that's impossible to isolate or recover from gracefully. I am not interested in examples of GDI+ code that works for you: I am looking for alternative libraries to use for image processing.

Answer 1

Most of the issues I have read about pertain to resources not being disposed properly.

I have used variants of this code time and time again with no issues from web applications:

public void GenerateThumbNail(HttpPostedFile fil, string sPhysicalPath, 
                              string sOrgFileName,string sThumbNailFileName,
                              ImageFormat oFormat, int rez)
{

    try
    {

        System.Drawing.Image oImg = System.Drawing.Image.FromStream(fil.InputStream);

        decimal pixtosubstract = 0;
        decimal percentage;

        //default
        Size ThumbNailSizeToUse = new Size();
        if (ThumbNailSize.Width < oImg.Size.Width || ThumbNailSize.Height < oImg.Size.Height)
        {
            if (oImg.Size.Width > oImg.Size.Height)
            {
                percentage = (((decimal)oImg.Size.Width - (decimal)ThumbNailSize.Width) / (decimal)oImg.Size.Width);
                pixtosubstract = percentage * oImg.Size.Height;
                ThumbNailSizeToUse.Width = ThumbNailSize.Width;
                ThumbNailSizeToUse.Height = oImg.Size.Height - (int)pixtosubstract;
            }
            else
            {
                percentage = (((decimal)oImg.Size.Height - (decimal)ThumbNailSize.Height) / (decimal)oImg.Size.Height);
                pixtosubstract = percentage * (decimal)oImg.Size.Width;
                ThumbNailSizeToUse.Height = ThumbNailSize.Height;
                ThumbNailSizeToUse.Width = oImg.Size.Width - (int)pixtosubstract;
            }

        }
        else
        {
            ThumbNailSizeToUse.Width = oImg.Size.Width;
            ThumbNailSizeToUse.Height = oImg.Size.Height;
        }

        Bitmap bmp = new Bitmap(ThumbNailSizeToUse.Width, ThumbNailSizeToUse.Height);
        bmp.SetResolution(rez, rez);
        System.Drawing.Image oThumbNail = bmp;

        bmp = null;

        Graphics oGraphic = Graphics.FromImage(oThumbNail);

        oGraphic.CompositingQuality = CompositingQuality.HighQuality;

        oGraphic.SmoothingMode = SmoothingMode.HighQuality;

        oGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic;

        Rectangle oRectangle = new Rectangle(0, 0, ThumbNailSizeToUse.Width, ThumbNailSizeToUse.Height);

        oGraphic.DrawImage(oImg, oRectangle);

        oThumbNail.Save(sPhysicalPath  + sThumbNailFileName, oFormat);

        oImg.Dispose();

    }
    catch (Exception ex)
    {
        Response.Write(ex.Message);
    }

}

Answer 2

You may have a look at http://gd-sharp.sourceforge.net/ which is a wrapper for the GD library. I haven't tested it but it seems promising.