A critical issue in function _setDots

[samiswt]

A variable named position in _setDots function defined a parametric formula of a circle. Left property of position should be X coordinate and top should be Y, then the parametric formula of the circle should be:

left: radius * cos(angle) + origin.x;
top: radius * sin(angle) + origin.y;

Since circle is a symmetric shape, so you will never catch the issue.