!7

sclass LockMatrix > DynModule {
  transient int n;
  transient BitSet data;
  transient JComponent canvas;
  
  JComponent visualize() {
    ret awtEvery(canvas = JComponent() {
      public void paint(Graphics2D g) {
        int w = getWidth(), h = getHeight();
        int rows = ifloor(sqrt(n));
        if (rows == 0) fillRect(g, 0, 0, w, h, Color.white);
        int cols = (n+rows-1)/rows;
        L<Rect> tiles = tileRects(w, h, cols, rows);
        for i over tiles:
          fillRect(g, tiles.get(i), main.contains(data, i) ? Color.red : Color.black);
      }
    }, 1000, r updateMe);
  }
  
  void update {
    new BitSet bs;
    L l = dm_listModules();
    for i over l:
      if (getLockOwner((Lock) get(l, 'lock)) != null)
        bs.set(i);
    setFields(n := l(l), data := bs);
    repaint(canvas);
  }
}