string url = "http://xxxxxxxxxxxxxxx";
            QRCodeEncoder qrCodeEncoder = new QRCodeEncoder();
            qrCodeEncoder.QRCodeEncodeMode = QRCodeEncoder.ENCODE_MODE.BYTE;
            qrCodeEncoder.QRCodeScale = 4;
            qrCodeEncoder.QRCodeVersion = 8;
            qrCodeEncoder.QRCodeErrorCorrect = QRCodeEncoder.ERROR_CORRECTION.M;
            System.Drawing.Bitmap image = qrCodeEncoder.Encode(url);
            System.IO.MemoryStream MStream = new System.IO.MemoryStream();
            image.Save(MStream, System.Drawing.Imaging.ImageFormat.Png);
            Context.Response.ClearContent();
            Context.Response.ContentType = "image/Png";
            Context.Response.BinaryWrite(MStream.ToArray());