protected override void writeCustomXml(XmlTextWriter writer)
{
writer.WriteStartElement("image");
string fileName = Path.GetTempPath() + "mazioPictureShape.png";
PngFormat format = new PngFormat();
Img.Save(fileName, format.getCodecInfo(), format.getParameters());
byte[] bytes = File.ReadAllBytes(fileName);
writer.WriteBase64(bytes, 0, bytes.Length);
writer.WriteEndElement();
}