How to know if Offset is inside circle - flutter

Question

In my code I have CircleAvatar with border. I want to know if user tap exactly on border. For this I need to check if tap is inside big circle (Container), but not inside small circle (CircleAvatar).
Does anybody know how could I check this?
Widget build(BuildContext context) {
return Listener(
child: Container(
key: key,
padding: EdgeInsets.all(8.0),
decoration: ShapeDecoration(shape: CircleBorder(), color: Colors.yellow),
child: CircleAvatar(
backgroundImage: NetworkImage(widget.imgSrc),
radius: 60.0,
),
),
onPointerDown: (event) {
if (renderBox == null) {
renderBox = key.currentContext?.findRenderObject();
}
Rect rect = renderBox.paintBounds;
// todo ......
},
);
}

Answer 1

You should use the Pythagore theorem to check if the Offset is in a circle :
import 'dart:math';
/// check if a [point] is in a circle of a given [radius]
bool isPointInside(Offset point, double radius) =>
pow(point.dx, 2) + pow(point.dy, 2) < pow(radius, 2);
Do this for the big and small circle and check if the results match what you want.
Edit : removed the sqrt in favour of pow(radius) as suggested by #randal-schwartz

Answer 2

Maybe it's not the best way, but I've found some solution
Rect bigRect = renderBox.paintBounds.shift(renderBox?.localToGlobal(Offset.zero));
Rect smallRect = bigRect.deflate(padding);
Path path = Path()
..fillType = PathFillType.evenOdd
..addOval(bigRect)
..addOval(smallRect);
if (path.contains(event.position)) { // todo...
P.S. Muldec's solution can be used too, it works, but I was looking for another type, like contains