fillText(text, x, y, font, textAlign, fillStyle) {
    this._ctx.beginPath();
    this._ctx.font = font;
    this._ctx.textAlign = textAlign;
    this._ctx.fillStyle = fillStyle;
    this._ctx.fillText(text, x, y);
    this._ctx.closePath();
  }
Create a filled text
@param {string} text
@param {number} x
@param {number} y
@param {string} font
@param {string} textAlign
@param {string} fillStyle