private void appendZone(Document doc, Element parent, BxZone zone, Object... hints)
     throws TransformationException {
   Element node = doc.createElement("Zone");
   appendPropertyIfNotNull(doc, node, "ZoneID", zone.getId());
   appendBounds(doc, node, "ZoneCorners", zone.getBounds(), hints);
   appendPropertyIfNotNull(doc, node, "ZoneNext", zone.getNextId());
   Element insetsNode = doc.createElement("ZoneInsets");
   insetsNode.setAttribute("Top", "");
   insetsNode.setAttribute("Bottom", "");
   insetsNode.setAttribute("Left", "");
   insetsNode.setAttribute("Right", "");
   node.appendChild(insetsNode);
   appendProperty(doc, node, "ZoneLines", "");
   if (zone.getLabel() != null) {
     if (ZONE_LABEL_MAP.get(zone.getLabel()) != null
         && !ZONE_LABEL_MAP.get(zone.getLabel()).isEmpty()) {
       appendClassification(doc, node, ZONE_LABEL_MAP.get(zone.getLabel()).toUpperCase(), "");
     } else {
       throw new TransformationException("Writing down an unknown zone label: " + zone.getLabel());
     }
   }
   for (BxLine line : zone.getLines()) {
     appendLine(doc, node, line, hints);
   }
   parent.appendChild(node);
 }
  private BxPage parsePageNode(Element elem) {
    BxPage page = new BxPage();

    double minX = 0, minY = 0, maxX = 0, maxY = 0;
    boolean started = false;

    List<Element> e = getChildren("Zone", elem);
    for (Element zo : e) {
      BxZone zon = parseZoneNode(zo);
      page.addZone(zon);

      BxBounds zoneBounds = zon.getBounds();
      if (!started) {
        minX = zoneBounds.getX();
        minY = zoneBounds.getY();
        maxX = zoneBounds.getX() + zoneBounds.getWidth();
        maxY = zoneBounds.getY() + zoneBounds.getHeight();
        started = true;
      }

      if (zoneBounds.getX() < minX) {
        minX = zoneBounds.getX();
      }
      if (zoneBounds.getX() + zoneBounds.getWidth() > maxX) {
        maxX = zoneBounds.getX() + zoneBounds.getWidth();
      }
      if (zoneBounds.getY() < minY) {
        minY = zoneBounds.getY();
      }
      if (zoneBounds.getY() + zoneBounds.getHeight() > maxY) {
        maxY = zoneBounds.getY() + zoneBounds.getHeight();
      }
    }

    Collections.sort(
        page.getZones(),
        new Comparator() {

          @Override
          public int compare(Object t, Object t1) {
            BxZone z1 = (BxZone) t;
            BxZone z2 = (BxZone) t1;
            int ret = Double.compare(z1.getBounds().getY(), z2.getBounds().getY());
            if (ret == 0) {
              ret = Double.compare(z1.getBounds().getX(), z2.getBounds().getX());
            }
            return ret;
          }
        });
    return page.setBounds(new BxBounds(minX, minY, maxX - minX, maxY - minY));
  }