addPie method
Adds a pie
Implementation
void addPie(Rect bounds, double startAngle, double sweepAngle) {
startFigure();
addArc(bounds, startAngle, sweepAngle);
_addPoint(
Offset(bounds.left + bounds.width / 2, bounds.top + bounds.height / 2),
PathPointType.line);
closeFigure();
}