ı create canvas for users can draw.And ı am trying to do use in that canvas another screen. I add button for clear. But ı cant access the clear method,

when I looked at the previous opened questions on stackoverflow, I saw that it is used in InheritedWidget. at first I used an object from my canvas class, but I couldn’t see the method.

import 'dart:ui';
import 'package:flutter/material.dart';

import '../../../core/util/app_sizes.dart';

class ThetaCanvas extends StatefulWidget {
  const ThetaCanvas({Key? key}) : super(key: key);

  @override
  State<ThetaCanvas> createState() => _ThetaCanvasState();
}

class _ThetaCanvasState extends State<ThetaCanvas> {
  List<DrawingArea?> points = [];
  late double opacity;

  @override
  void initState() {
    super.initState();
    opacity = 1.0;
  }

   clearThetaCanvas() {
    setState(() {
      points.clear();
    });
  }

  @override
  Widget build(BuildContext context) {
    return ClipRect(
      child: Container(
        height: AppSizes.screenHeight / 4,
        width: AppSizes.screenWidth,
        decoration: BoxDecoration(color: Colors.white70, borderRadius: BorderRadius.circular(25)),
        child: GestureDetector(
          onPanDown: (details) {
            setState(() {
              points.add(DrawingArea(
                point: details.localPosition,
                areaPaint: Paint()
                  ..color = Colors.black.withOpacity(opacity)
                  ..strokeCap = StrokeCap.round
                  ..isAntiAlias = true
                  ..strokeWidth = 2.0,
              ));
            });
          },
          onPanUpdate: (details) {
            setState(() {
              points.add(DrawingArea(
                point: details.localPosition,
                areaPaint: Paint()
                  ..color = Colors.black.withOpacity(opacity)
                  ..strokeCap = StrokeCap.round
                  ..isAntiAlias = true
                  ..strokeWidth = 2.0,
              ));
            });
          },
          onPanEnd: (details) {
            points.add(null);
          },
          child: CustomPaint(
            size: Size.infinite,
            painter: DrawingPainter(pointsList: points),
          ),
        ),
      ),
    );
  }
}

class DrawingPainter extends CustomPainter {
  List<DrawingArea?> pointsList;

  DrawingPainter({required this.pointsList});

  @override
  void paint(Canvas canvas, Size size) {
    for (int i = 0; i < pointsList.length - 1; i++) {
      if (pointsList[i] != null && pointsList[i + 1] != null) {
        canvas.drawLine(
          pointsList[i]!.point,
          pointsList[i + 1]!.point,
          pointsList[i]!.areaPaint,
        );
      } else if (pointsList[i] != null && pointsList[i + 1] == null) {
        canvas.drawPoints(PointMode.points, [pointsList[i]!.point], pointsList[i]!.areaPaint);
      }
    }
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    return true;
  }
}

class DrawingArea {
  Offset point;
  Paint areaPaint;

  DrawingArea({required this.point, required this.areaPaint});
}

and here is my button

class NextAndClearButton extends StatelessWidget {
  const NextAndClearButton({super.key});

  @override
  Widget build(BuildContext context) {
    final ThetaCanvas thetaCanvas = ThetaCanvas();

    return TextButton(
      onPressed: () {
        
      },
      style: ButtonStyle(
        splashFactory: InkRipple.splashFactory,
        overlayColor: MaterialStateProperty.resolveWith<Color>(
          (Set<MaterialState> states) {
            if (states.contains(MaterialState.pressed)) {
              return Colors.white
                  .withOpacity(0.4); 
            }
            return Colors.transparent; 
          },
        ),
      ),
      child: Container(
        padding: const EdgeInsets.all(8),
        decoration: BoxDecoration(
          border: Border.all(color: Colors.white), 
          borderRadius: BorderRadius.circular(25), 
        ),
        child: Row(
          mainAxisSize: MainAxisSize.min, 
          children: [
            Text(
              'NEXT',
              style: Theme.of(context).textTheme.displaySmall?.copyWith(color: Colors.white),
            ),
            const Icon(
              Icons.chevron_right_outlined,
              color: Colors.white,
              size: 40,
            ),
          ],
        ),
      ),
    );
  }
}

when ı write the thetaCanvas.clearThetaCanvas its says

The method ‘clearThetaCanvas’ isn’t defined for the type ‘ThetaCanvas’.
Try correcting the name to the name of an existing method, or defining a method named ‘clearThetaCanvas’