如何在Java和Kotlin中像弯曲的贝塞尔曲线一样绘制弯曲的路径

Question

如何在Android中使用Java或Kotlin（如bezier方法）在Flutter中创建自定义形状？看这些图片，告诉我是否可以用Java创建这种形状？我搜索了更多次，但我无法理解是否有可能这样做以及使用女巫类。

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Answer 1

使用CustomPainter并使用path.quadraticBezierTo您可以参考此文档https://medium.com/@felixblaschke/fancy-background-animations-in-flutter-4163d50f5c37github https://github.com/felixblaschke/simple_animations_example_app

https://github.com/felixblaschke/simple_animations_example_app/blob/master/lib/examples/fancy_background.dart中的代码段

class CurvePainter extends CustomPainter {
  final double value;

  CurvePainter(this.value);

  @override
  void paint(Canvas canvas, Size size) {
    final white = Paint()..color = Colors.white.withAlpha(60);
    final path = Path();

    final y1 = sin(value);
    final y2 = sin(value + pi / 2);
    final y3 = sin(value + pi);

    final startPointY = size.height * (0.5 + 0.4 * y1);
    final controlPointY = size.height * (0.5 + 0.4 * y2);
    final endPointY = size.height * (0.5 + 0.4 * y3);

    path.moveTo(size.width * 0, startPointY);
    path.quadraticBezierTo(
        size.width * 0.5, controlPointY, size.width, endPointY);
    path.lineTo(size.width, size.height);
    path.lineTo(0, size.height);
    path.close();
    canvas.drawPath(path, white);
  }

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