srecord noeq G22Tiling<Img extends WidthAndHeight>(Img img) {
  new L<Tile> tiles;
  
  // number of pixels covered by all tiles
  int pixelsCovered;
  
  // for each pixel: tile index+1 (or 0 for empty)
  int[] tileMatrix;

  // index = dual log of tile size, value = tile index
  //new L<IntBuffer> tilesBySize;
  
  // yay, extending Rect to save space
  class Tile extends Rect {
    int index;
    int color; // tile color as defined by the tiler

    *(int *index, int *color, Rect position) {
      position(position);
    }
    
    Rect position() { this; }
    
    selfType position(Rect r) {
      x = r.x; y = r.y; w = r.w; h = r.h;
      this;
    }
    
    S area_str() {
      ret nPixels(area());
    }
    
    double ratioToImage() {
      ret doubleRatio(area(), imageArea());
    }
    
    S percent_str() {
      ret formatDoubleX(ratioToImage()*100, 2) + "% of image";
    }
    
    toString {
      ret intToHex_fullLength(color) + " colored tile covering " + percent_str() +  " at " + super.toString();
    }
    
    // Lists of neighbors in all 4 directions (index like NESWDirection)
    // (If only a corner is touching, it's not a neighbor.)
    // Not used yet
    //Cl<Tile>[] neighbors;
  }
  
  int w() { ret img.w(); }
  int h() { ret img.h(); }
  int imageArea() { ret img.area(); }
  
  void initTileMatrix {
    tileMatrix = new int[w()*h()];
  }
  
  int numTiles() { ret l(tiles); }
  
  L<Tile> get() { ret tiles; }
}