half_circle_progress_bar_painter_paint_v1.dart

@override
void paint(Canvas canvas, Size size) {
  final center = size.bottomCenter(Offset(0, -dotRadius));

  final lengthOfHalfCircle = pi * startBarRadius;

  final dotsNumber = (lengthOfHalfCircle / _dotsSizeWithSpacing).floor();

  final angleStep = _halfCircle / (dotsNumber - 1);
  var angle = _startAngle;

  final progressItems = (dotsNumber * progress).toInt();

  for (var dot = 0; dot < dotsNumber; dot++) {
    final radian = pi * 2 * angle / _circle;

    canvas.drawCircle(
      Offset(
        radius * sin(radian) + center.dx,
        radius * cos(radian) + center.dy,
      ),
      dotRadius,
      dot < progressItems ? _progressPaint : _paint,
    );

    angle -= angleStep;
  }
}