在不更新状态/重建小部件的情况下重画CustomPaint？

class MyCustomPaint extends StatefulWidget {
  @override
  _MyCustomPaintState createState() => _MyCustomPaintState();
}

class _MyCustomPaintState extends State<MyCustomPaint> {
  RenderRepaintBoundary? _boundary;

  @override
  Widget build(BuildContext context) {
    return RepaintBoundary(
      key: GlobalKey(),
      child: CustomPaint(
        painter: MyPainter(),
      ),
    );
  }

  void repaintCustomPaint() {
    _boundary?.markNeedsPaint();
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    _boundary = context.findRenderObject() as RenderRepaintBoundary?;
  }
}

class MyPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    // 绘制自定义内容
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    // 根据需要重画的条件返回true或false
    return false;
  }
}