animated-donut-chart-03

donut-chart-painter.dart

class DonutChartPainter extends CustomPainter {
  final List<DataItem> dataset;
  DonutChartPainter(this.dataset);

  @override
  void paint(Canvas canvas, Size size) {
    final c = Offset(size.width / 2.0, size.height / 2.0);
    final radius = size.width * 0.9;
    final rect = Rect.fromCenter(center: c, width: radius, height: radius);
    final fullAngle = 360.0;
    var startAngle = 0.0;
    
    //draw sectors
    dataset.forEach((di) {
      final sweepAngle = di.value * fullAngle * pi / 180.0;
      drawSector(canvas, di, rect, startAngle, sweepAngle);
      drawLabels(canvas, c, radius, startAngle, sweepAngle, di.label);
      startAngle += sweepAngle;
    });

    // draw the middle
    canvas.drawCircle(c, radius * 0.3, midPaint);

    // draw title
    drawTextCentered(canvas, c, "Favourite\nMovie\nGenres",
        textFieldTextBigStyle, radius * 0.6, (Size sz) {});
  }