How to perform reveal Animation in flutter? - flutter

Question

I want to perform reveal Animation in flutter, Like I want to perform only that part where the circle resides. So i want to know how to reveal a particular text behind that circle.
import 'package:flutter/material.dart';
class Search extends StatefulWidget {
const Search({super.key});
#override
State<Search> createState() => _SearchState();
}
class _SearchState extends State<Search> {
double x1 = 100, y1 = 100, x1Prev = 100.0, y1Prev = 100.0;
#override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
body: Stack(
children: [
Container(
color: Colors.black,
child: Center(
child: Text(
"This is just a test and i am working on it",
style: TextStyle(color: Colors.white, fontSize: 29),
),
),
),
Container(
color: Colors.black,
),
Positioned(
left: x1,
top: y1,
child: GestureDetector(
onPanUpdate: (details) {
setState(() {
x1 = x1Prev + details.localPosition.dx;
y1 = y1Prev + details.localPosition.dy;
print(details.localPosition.dx);
});
},
onPanDown: (d) {
x1Prev = x1;
y1Prev = y1;
},
child: Container(
height: 100,
width: 100,
decoration: BoxDecoration(
shape: BoxShape.circle,
border: Border.all(color: Colors.white)),
),
),
)
],
),
),
);
}
}
I try this code and it only works to move circle at specific position,But i am not able to think how to display element behind that circle.