我同意您必须将 CustomPainter 放入具有大小的小部件中。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 可以通过一些重构来为您处理该测试。首先要注意的是,路径不需要在每个 Paint() 上重建 - 它可以在构造函数中构建。这使得 CustomPainter 的 hitTest 可以简单地询问点击是在路径内部还是外部。
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),
),
),
);
}
}
我用过达特..
(级联)语法来清理路径。 (我认为你的should...
测试被否定。)我添加了一个 StatelessWidget 只是作为SizedBox
and GestureDetector
.