function fillRect(x, y, w, h, color) {
  for (let ii = 0; ii < w * h; ++ii) {
    const xx = (ii % w) + x;
    const yy = ((ii / w) | 0) + y;
    this.drawPixel(xx, yy, color);
  };
}
@param {Number} x
@param {Number} y
@param {Number} w
@param {Number} h
@param {Array} color