Flutter

我同意您必须将CustomPainter放入具有大小的窗口小部件中。它可能是一个SizedBox，所以我在这里使用了它。幸运的是，您不需要进行手动命中测试，因为CustomPainter可以通过一些重构即可为您处理。首先要注意的是，不需要在每个paint（）上重建路径-
可以在构造函数中构建路径。这使CustomPainter的hitTest可以简单地询问水龙头在路径内还是路径外。

class _SegmentPainter extends CustomPainter {  static const offset = -pi / 2;  double start;  double end;  double innerRadius;  double outerRadius;  Color color;  Path path;  _SegmentPainter(      this.start, this.end, this.innerRadius, this.outerRadius, this.color) {    path = new Path()      ..arcTo(          Rect.fromCircle(center: new Offset(0.0, 0.0), radius: outerRadius),          offset + start,          end - start,          true)      ..relativeLineTo(-cos(offset + end) * (outerRadius - innerRadius),          -sin(offset + end) * (outerRadius - innerRadius))      ..arcTo(          Rect.fromCircle(center: new Offset(0.0, 0.0), radius: innerRadius),          offset + end,          start - end,          false)      ..close();  }  @override  bool shouldRepaint(_SegmentPainter oldDelegate) {    return oldDelegate.start != start ||        oldDelegate.end != end ||        oldDelegate.innerRadius != innerRadius ||        oldDelegate.outerRadius != outerRadius ||        oldDelegate.color != color;  }  @override  bool shouldRebuildSemantics(_SegmentPainter oldDelegate) => true;  @override  void paint(Canvas canvas, Size size) {    canvas.drawPath(        path,        new Paint()          ..color = color          ..style = PaintingStyle.fill);  }  @override  bool hitTest(Offset position) {    return path.contains(position);  }}class SegmentWidget extends StatelessWidget {  @override  Widget build(BuildContext context) {    return new GestureDetector(      onTap: () => print('tap'),      child: new SizedBox(        width: 250.0,        height: 250.0,        child: new CustomPaint(          painter: new _SegmentPainter(0.0, 2.8, 150.0, 200.0, Colors.orange),        ),      ),    );  }}

我使用了Dart

..

should...

SizedBox

GestureDetector