public char getPDFVersion() {
return _pdfVersion == null ? '0' : _pdfVersion.charValue();
}
public void layout() {
LayoutContext c = newLayoutContext();
BlockBox root = BoxBuilder.createRootBox(c, _doc);
root.setContainingBlock(new ViewportBox(getInitialExtents(c)));
root.layout(c);
Dimension dim = root.getLayer().getPaintingDimension(c);
root.getLayer().trimEmptyPages(c, dim.height);