this is pure pi chart in dart programming language

pi_chart.dart

// chart data

List expenses = [
  {"name":"Groceries","amount":500.0},
  {"name":"Online Shopping","amount":100.0},
  {"name":"Eating out","amount":80.0},
  {"name":"Bills","amount":50.0},
  {"name":"Subscriptions","amount":100.0},
  {"name":"Fees","amount":30.0},
];

 List pieColors = [
  Colors.indigo[400],
   Colors.blue,
   Colors.green,
   Colors.amber,
   Colors.deepOrange,
   Colors.brown,
];

// custom painter class for this data 

class PiChartPainter extends CustomPainter{
  @override
  void paint(Canvas canvas, Size size) {

    Offset center  = Offset(size.width /2 , size.height /2);
    double radius = min(size.width /2 , size.height /2);
    var paint = new Paint()
    ..style = PaintingStyle.stroke
    ..strokeWidth =  100 ;

    double total = 0 ;

    expenses.forEach((element) {
      total += element['amount'];

    });

    var start = -pi / 4;


    for(int i = 0 ; i < expenses.length ; i ++){
      var currentExpense = expenses[i];
      var sweepRadius = (currentExpense['amount'] / total) * 2 * pi  ;
      paint.color = pieColors[i];
      canvas.drawArc(Rect.fromCircle(center: center,radius: radius), start, sweepRadius, false, paint);
      start += sweepRadius ;

    }

  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    // TODO: implement shouldRepaint
    return true ;
  }

}

// implementation :- 
/*
CustomPaint(

          foregroundPainter: PiChartPainter(),
          child: Container(),
        )
        
        */