static Pair<CirclesAndLines, Canvas> showWebWithAutoLayout(Web web) {
  if (web == null) null;
  Pair<CirclesAndLines, Canvas> p = showWeb_noAutoLayout(web);
  calAutoLayout(p.a, p.b);
  ret p;
}

static Pair<CirclesAndLines, Canvas> showWebWithAutoLayout(Web web, int w, int h) {
  if (web == null) null;
  Pair<CirclesAndLines, Canvas> p = showWeb_noAutoLayout(web, w, h);
  calAutoLayout(p.a, p.b);
  ret p;
}