srecord noeq FillOnePath(OnePathWithOrigin path) {

  // do we fill the right-hand side or the left-hand side when

  // walking the path

  settable bool rhsIsInside;

  Rect r; // bounds of path

  BitSet inBorder; // is pixel part of path itself?

  BitSet inside;   // is pixel inside the filled path?

  run {

    r = path.bounds();

    int size = r.w*r.h;

    inBorder = new BitSet(size);

    inside = new BitSet(size);

    Pt last = null;

    for (Pt p : path.pointIterator()) {

      int idx = (p.x-r.x)+(p.y-r.y)*r.w;

      inBorder.set(idx);

      if (last != null) {

        int dx = p.x-last.x, dy = p.y-last.y;

        if (dx == 0 && dy == 0) {}

        else if (dy == 0)

          setInside(rhsIsInside ? last.x+dx : last.y-dx, p.y);

        else if (dx == 0)

          setInside(p.x, rhsIsInside ? last.x-dx : last.x+dx);

        else { /*TODO*/ }

      }

      last = p;

    }

  }

  void setInside(int x, int y) {

    if (!rectContains(r, x, y)) ret;

    int idx = (x-r.x)+(y-r.y)*r.w;

    inside.set(idx);

  }

}