* @param graphSheet the preview graph sheet
* @param supportSize the support size of the exported image
*/
protected Document buildDOM(GraphSheet graphSheet, SupportSize supportSize) {
// creates SVG document
DOMImplementation impl = SVGDOMImplementation.getDOMImplementation();
DocumentType doctype = impl.createDocumentType(
"-//W3C//DTD SVG 1.1//EN",
"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd",
"");
doc = impl.createDocument(namespaceURI, "svg", doctype);
// initializes CSS and SVG specific DOM interfaces
UserAgent userAgent = new UserAgentAdapter();
DocumentLoader loader = new DocumentLoader(userAgent);
BridgeContext ctx = new BridgeContext(userAgent, loader);