srecord noeq RegionToGSI(IPixelSet region) extends Meta {

  Color color;

  gettable GSI gsi;

  GSI get() {

    if (region == null) null;

    if (region cast IImageRegion)

      gsi.color(region.color());

    Rect r = region.bounds();

    int x1 = r.x1(), y1 = r.y1();

    int y2 = r.y2(), w = r.w, h = y2-y1;

    gsi = new GSI;

    gsi.y1 = y1;

    gsi.rowStarts = new int[h];

    new IntBuffer xData;

    for (int y = y1; y < y2; y++) {

      reMutable y;

      gsi.rowStarts[y-y1] = l(xData);

      L<IntRange> streaks = shiftIntRanges(x1, genericStreaks(w, x -> region.contains(x1+x, y)));

      xData.addAll(intRangesToIntArray_startAndLength(streaks));

    }

    gsi.xData = xData.toArray();

    ret gsi;

  }

}