drawProjectPoint(ctx, px, py, style) {
    const vx = this.gridCanvas.p2vX(px), vy = this.gridCanvas.p2vY(py);
    const savedCtx = { fillStyle: ctx.fillStyle, lineWidth: ctx.lineWidth,
      strokeStyle: ctx.strokeStyle };
    // TODO: The style is to-be-implemented
    ctx.fillStyle = '#EE2222';
    ctx.beginPath();
    ctx.arc(vx, vy, this.gridCanvas.resolution * 4, 0, 2*Math.PI);
    ctx.fill()
    Object.assign(ctx, savedCtx);
  }
Draw a point with the given project coordinate
@param { CanvasRenderingContext2D } ctx
@param { number } px Project x @param { number } py Project y
@param { string } style