sclass CheckerBoard2 is G2Drawable {
  settable int w = 256;
  settable int h = 256;
  
  settable double shiftX;
  settable double shiftY;
  
  settable double cellW = 8;
  settable double cellH = 8;
  
  settable Color color1 = Color.lightGray;
  settable Color color2 = Color.gray;
  
  selfType cellSize(double cellSize) {
    ret cellW(cellSize).cellH(cellSize);
  }
  
  public int getWidth() { ret w; }
  public int getHeight() { ret h; }
  
  public void drawOn(Graphics2D g) {
    int xofs = idiv_floor(shiftX, cellW);
    int yofs = idiv_floor(shiftY, cellH);
    double x1 = mod(shiftX, cellW)-cellW;
    double y1 = mod(shiftY, cellH)-cellH;
    
    bool bRow = odd(yofs^xofs);
    for (double y = y1; y < h; y += cellH) {
      bRow = !bRow;
      bool b = bRow;
      for (double x = x1; x < w; x += cellW) {
        b = !b;
        g.setColor(b ? color1 : color2);
        g.fill(new Rectangle2D.Double(x, y, cellW, cellH));
      }
    }
  }
}