half_circle_progress_bar.dart

class HalfCircleProgressBar extends StatelessWidget {
  const HalfCircleProgressBar({
    Key? key,
    required this.progress,
    required this.dotColor,
    required this.progressDotColor,
    this.dotRadius = _defaultDotRadius,
    this.startBarRadius = _defaultStartBarRadius,
    this.layers = _defaultLayers,
    this.layersSpacing = _defaultLayersSpacing,
    this.dotsSpacing = _defaultDotsSpacing,
  }) : super(key: key);

  final double progress;
  final double dotRadius;
  final double startBarRadius;
  final int layers;
  final double layersSpacing;
  final double dotsSpacing;
  final Color dotColor;
  final Color progressDotColor;

  static const _defaultDotRadius = 4.0;
  static const _defaultStartBarRadius = 68.0;
  static const _defaultLayers = 10;
  static const _defaultLayersSpacing = 1.0;
  static const _defaultDotsSpacing = 1.0;

  @override
  Widget build(BuildContext context) {
    final height = startBarRadius + (layersSpacing + dotRadius * 2) * layers;
    return ClipRect(
      child: CustomPaint(
        size: Size(height * 2, height),
        painter: _DiagramPainter(
          dotRadius: dotRadius,
          startBarRadius: startBarRadius,
          layers: layers,
          layersSpacing: layersSpacing,
          dotsSpacing: dotsSpacing,
          progress: progress,
          dotColor: dotColor,
          progressDotColor: progressDotColor,
        ),
      ),
    );
  }
}