I'm following this speed code tutorial (

This is what it resulted and I have no idea why the speed code video that I'm following doesn't show any errors and mine does.

CodePudding user response：

You have defined shouldRepaint function incorrectly.

You can see this file, I have updated it:

class WaveBasePainter extends CustomPainter {
  Paint? _paint; //4:03
  @override
  void paint(Canvas canvas, Size size) {
    _paint = Paint()
      ..color = Colors.grey.withOpacity(0.3)
      ..style = PaintingStyle.stroke
      ..strokeWidth = 1.5;

    canvas.translate(0, size.height / 2);
    canvas.scale(1, -1);

    for (int i = 0; i < size.width.toInt(); i  ) {
      double x = i.toDouble();
      double r = 2 * sin(i) - 2 * cos(4 * i)   sin(2 * i - pi * 24);
      r = r * 5;
      canvas.drawLine(Offset(x, r), Offset(x, -r), _paint!);
    }
  }

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