_drawBackground(ctx) {
    if (
      this.fontOptions.background !== undefined &&
      this.fontOptions.background !== "none"
    ) {
      ctx.fillStyle = this.fontOptions.background;
      const size = this.getSize();
      ctx.fillRect(size.left, size.top, size.width, size.height);
    }
  }
Draws the label background
@param {CanvasRenderingContext2D} ctx
@private