implement line chart with flutter

chart.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:ui' as ui;
class ChartPage extends StatefulWidget {
  const ChartPage({super.key});

  @override
  State<ChartPage> createState() => _ChartPageState();
}

class _ChartPageState extends State<ChartPage> {
  @override
  Widget build(BuildContext context) {
    return 

    Scaffold(
body: SizedBox.expand(
  child: Center(
    child: AspectRatio(
  aspectRatio: 3/2,
      child: CustomPaint(
      
      foregroundPainter: MyPainter(),
      child: Container(
      color: Colors.grey,
      ),
      
      ),
    ),
  ),
),
    );
  }
}


class MyPainter extends CustomPainter {

  @override
  void paint(Canvas canvas, Size size) {

 var paint = Paint()
 ..color =Colors.purple
 ..strokeWidth= 1
 
     ..style = PaintingStyle.stroke
 ;
 

    canvas.drawRect(
      
     Rect.fromCenter(center: 
     Offset(size.width/2, size.height/2)
     
     ,
      width: size.width, height: size.height)
    //  Offset(0, 0)
      ,
    
     paint);



var  horizontalLines = 5;
var horizontalSize=  size.height / (horizontalLines);
var linePainter =  Paint()
..color=Colors.purple
..style=PaintingStyle.fill
..strokeWidth=1
;

for (var i = 0; i < horizontalLines; i++) {
  var startY =  horizontalSize*(0+i);
canvas.drawLine(Offset(0, startY),
 Offset(size.width, startY), linePainter);
}


var  verticalLines = 5;
var verticalSize=  size.width / (verticalLines);
for (var i = 0; i < verticalLines; i++) {
  var startX =  verticalSize*(0+i);
canvas.drawLine(Offset(startX, 0),
 Offset(startX , size.height), linePainter);
}
var pathPaint = Paint()
..color = Colors.green 
..style =PaintingStyle.stroke
..strokeWidth=5;
var path = drawPath(true, size);
canvas.drawPath(path, pathPaint);

var innerPath = Path()
..addPath(path, Offset.zero)
..lineTo(size.width, size.height) 
..lineTo(0, size.height)
..close();

var innerPaint = Paint()
..shader = ui.Gradient.linear(
    Offset.zero,
    Offset(size.width , size.height),
    [
      Colors.green.withAlpha(240),
      Colors.transparent,
    ],
  )
..style =PaintingStyle.fill

;
canvas.drawPath(innerPath, innerPaint);





  }
Path drawPath(bool closePath , Size size ) {
  final width = size.width;
  final height = size.height;
  final path = Path();
  final segmentWidth = width / 3 / 2;
  path.moveTo(0, height);
  path.lineTo(size.width*.20, size.height*.80);
    path.lineTo(size.width*.35, size.height*.70);
    path.lineTo(size.width*.50, size.height*.70);
    path.lineTo(size.width*.70, size.height*.40);
    path.lineTo(size.width*.80, size.height*.90);
    path.lineTo(size.width*.90, size.height*.80);
    path.lineTo(size.width, size.height);

  // path.cubicTo(segmentWidth, height, 2 * segmentWidth, 0, 3 * segmentWidth, 0);
  // path.cubicTo(4 * segmentWidth, 0, 5 * segmentWidth, height, 6 * segmentWidth, height);

  return path;
}
  @override
  bool shouldRepaint(MyPainter oldDelegate) => false;

  @override
  bool shouldRebuildSemantics(MyPainter oldDelegate) => false;
}