is there a method to draw/fill a rounded rectangle?

Last, but not least: the fillRoundedRect variant of the abovementioned code:

  let ScreenWidth  = g.getWidth(),  CenterX = ScreenWidth/2;
  let ScreenHeight = g.getHeight(), CenterY = ScreenHeight/2;

  g.setBgColor('#000000');
  g.clear(false);

  g.fillRoundedRect = function fillRoundedRect (x1,y1, x2,y2, r) {
    let x,y;
    if (x1 > x2) { x = x1; x1 = x2; x2 = x; }
    if (y1 > y2) { y = y1; y1 = y2; y2 = y; }

    r = Math.min(r || 0, (x2-x1)/2, (y2-y1)/2);

    let cx1 = x1+r, cx2 = x2-r;
    let cy1 = y1+r, cy2 = y2-r;

    this.fillRect(x1,cy1, x2,cy2);

    x = r; y = 0;

    let dx,dy, Error = 0;
    while (y <= x) {
      dy = 1 + 2*y; y++; Error -= dy;
      if (Error < 0) {
        dx = 1 - 2*x; x--; Error -= dx;
      }

      this.drawLine(cx1 - x, cy1 - y,  cx2 + x, cy1 - y);
      this.drawLine(cx1 - y, cy1 - x,  cx2 + y, cy1 - x);
      this.drawLine(cx1 - x, cy2 + y,  cx2 + x, cy2 + y);
      this.drawLine(cx1 - y, cy2 + x,  cx2 + y, cy2 + x);
    }
  };

  g.setColor('#FFFFFF');
  g.fillRoundedRect(120,50, 50,120, 100);

Now I have everything I need - thank you very much for your assistance!

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