Flutter：使用ScrollController绑定CustomPainter

问题描述

我有一个像下面的CustomPainter，我希望它与包含ListView.builder的父窗口小部件绑定吗？
预期的行为：当我向上或向下滚动时，画家应该绘画。

import 'dart:math';
import 'package:Flutter/material.dart';

class PlayerPainter extends CustomPainter {
  final Animation<double> animation;
  final Paint backgroundPaint;
  final Color bgColor;
  final Color thumbColor;
  final Paint sliderPaint;
  final Paint thumbPaint;

  PlayerPainter({this.animation,this.bgColor,this.thumbColor})
      : backgroundPaint = Paint()..color = bgColor,sliderPaint = Paint()
          ..style = PaintingStyle.stroke
          ..strokeWidth = 3.0,thumbPaint = Paint()..color = thumbColor,super(repaint: animation);

  @override
  void paint(Canvas canvas,Size size) {
    final value = animation.value;
    final radius = size.width * 0.5;
    final thumbRadius = 4.0;
    final rect = Rect.fromCircle(center: Offset(radius,size.height),radius: radius);
    final thumbPosX = radius + (radius * -cos(value * pi));
    final thumbPosY = (size.height - thumbRadius) + ((size.height - thumbRadius) * -sin(value * pi));
    sliderPaint.shader = LinearGradient(colors: [
      const Color(0xFFCC2B5E),const Color(0xFF753A88),const Color(0xFFCC2B5E),]).createShader(rect);

    canvas.drawArc(rect,pi,false,backgroundPaint);
    canvas.drawArc(rect,value * pi,sliderPaint);
    canvas.drawCircle(Offset(thumbPosX,thumbPosY),thumbRadius,thumbPaint);
  }

  @override
  bool shouldRepaint(PlayerPainter oldDelegate) => true;
}

parent.dart

@override
  void initState() {
    _controller = AnimationController(vsync: this);
    _scrollController.addListener(() {
      setState(() {
        _controller = AnimationController(
          value: _scrollController.offset,duration: Duration(seconds: 0),vsync: this,);
      });
    });
}
PlayerView(
...
  controller: _controller,),

════════基础库捕获到异常Exception ══════════════════ _MusicScreenState是SingleTickerProviderStateMixin，但是创建了多个代码。

解决方法

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