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

Here is a version for filled rectangles. Performance is roughly the same, faster for r<=12, slower for larger radii. Performance is an issue here, on my Bangle2, "bFillRoundedRectangle(10,10,160,160,13);" takes about 85ms. For UI use, i think a LUT for rounded corners would be the best approach. All coordinates needed for a circle covering the complete screen would take up just 52 bytes.

 function bFillRoundedRectangle (x1,y1,x2,y2,r) {
    var f = 1 - r;
    var ddF_x = 0;
    var ddF_y = -2 * r;
    var x = 0;
    var y = r;
    g.fillRect(x1+r,y1,x2-r,y2);
    var cx1=x1+r;
    var cx2=x2-r;
    var cy1=y1+r;
    var cy2=y2-r;
    while(x < y)
    {
      if(f >= 0)
      {
        y--;
        ddF_y += 2;
        f += ddF_y;
      }
      x++;
      ddF_x += 2;
      f += ddF_x + 1;
      g.drawLine(cx1-x,cy1-y,cx1-x,cy2+y);
      g.drawLine(cx1-y,cy1-x,cx1-y,cy2+x);
      g.drawLine(cx2+x,cy1-y,cx2+x,cy2+y);
      g.drawLine(cx2+y,cy1-x,cx2+y,cy2+x);
    }
  }