flutter - 我正在尝试在 flutter 中绘制自定义形状，但是不幸的是该形状没有出现，我只看到了白色的容器

Question

这是自定义形状代码

class SignInPageCustomShape extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint();
    final Color myColor = Colors.black12;
    paint.color = myColor;
    paint.style = PaintingStyle.fill;
    final path = Path();
    path.moveTo(0, size.height * 0.9167);
    path.quadraticBezierTo(
      size.width * 0.25,
      size.height * 0.875,
      size.width * 0.5,
      size.height * 0.9167,
    );
    path.quadraticBezierTo(
      size.width * 0.75,
      size.height * 0.9584,
      size.width * 1.0,
      size.height * 0.9167,
    );
    path.lineTo(size.width, size.height);
    path.lineTo(0, size.height);

    canvas.drawPath(path, paint);
  }

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

这是我的小部件树，我不知道出了什么问题，我试图将容器放在不同的位置，但是得到的结果是一样的，堆栈溢出正在要求我解释更多，但是我没有别的解释。

class Paint extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Container(
          color: Colors.white,
          child: CustomPaint(
            painter: SignInPageCustomShape(),
          ),
        ),
      ),
    );
  }
}

Answer 1

您面临的问题可能是因为您尚未在CustomPaint中定义子项
我添加了一个空容器并运行代码，并得到了此结果
Screenshot
也建议不要命名StatelessWidget Paint

class Paint extends StatelessWidget {

以下方法接受两个类型为Paint的参数，因为您定义了一个自定义小部件，该小部件的名称与本例中传递错误的参数相同

canvas.drawPath(path, paint);

我用来获取此响应中附加结果的代码:
绘画小部件:

class PaintWidget extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Container(
          color: Colors.white,
          child: CustomPaint(
            painter: SignInPageCustomShape(),
            child: Container(),
          ),
        ),
      ),
    );
  }
}

SignInPageCustomShape小部件:

class SignInPageCustomShape extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint();

    final Color myColor = Colors.black12;
    paint.color = myColor;
    paint.style = PaintingStyle.fill;
    final path = Path();
    path.moveTo(0, size.height * 0.9167);
    path.quadraticBezierTo(
      size.width * 0.25,
      size.height * 0.875,
      size.width * 0.5,
      size.height * 0.9167,
    );

    path.quadraticBezierTo(
      size.width * 0.75,
      size.height * 0.9584,
      size.width * 1.0,
      size.height * 0.9167,
    );

    path.lineTo(size.width, size.height);
    path.lineTo(0, size.height);

    canvas.drawPath(path, paint);
  }

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