private GraphicsDocument createFeatureDocument(StringWriter writer) throws RenderException {
if (TileMetadata.PARAM_SVG_RENDERER.equalsIgnoreCase(renderer)) {
DefaultSvgDocument document = new DefaultSvgDocument(writer, false);
document.setMaximumFractionDigits(MAXIMUM_FRACTION_DIGITS);
document.registerWriter(InternalFeatureImpl.class, new SvgFeatureWriter(getTransformer()));
document.registerWriter(InternalTileImpl.class, new SvgTileWriter());
return document;
} else if (TileMetadata.PARAM_VML_RENDERER.equalsIgnoreCase(renderer)) {
DefaultVmlDocument document = new DefaultVmlDocument(writer);
int coordWidth = tile.getScreenWidth();
int coordHeight = tile.getScreenHeight();