srecord noeq G22_RegionToSSI(IImageRegion region) {
  SSI get() {
    if (region == null) null;
    Rect r = region.bounds();
    int x1 = r.x1(), y1 = r.y1(), y2 = r.y2(), h = y2-y1, w = r.w;
    SSI ssi = new SSI(y1, y2);
    ssi.color(region.color());
    short[] data = new[h*2];
    for (int y = y1; y < y2; y++) {
      reMutable y;
      L<IntRange> streaks = genericStreaks(w, x -> region.contains(x1+x, y));
      IntRange range = selectHorizontalPart(streaks);
      int i = (y-y1)*2;
      data[i] = toShort_enforce(x1+range.start);
      data[i+1] = toShort_enforce(x1+range.end);
    }
    ssi.data(data);
    ret ssi;
  }
  
  swappable IntRange selectHorizontalPart(L<IntRange> parts) {
    ret first(parts);
  }
}

Began life as a copy of #1035603