Flutter moving point over image - flutter

Question

I want to create a moving point that moves across an image. The picture is drawn on canvas. The point should approach the specified x and y coordinates.Image and point are generated. The point should move to the new specified position every 500ms by a timer.But it only moves when I move the mouse over buttons on the app.
class five_og extends StatefulWidget {
#override
State createState() {
return _five_og();
}
}
class _five_og extends State<five_og> {
ui.Image? image;
Timer? timer;
void refreshImage() {
if (i >= xList.length - 1) {
i = 0;
}
ImagePainter(image!);
i++;
}
#override
void dispose() {
super.dispose();
timer!.cancel();
}
#override
void initState() {
super.initState();
loadImage('assets/images/Erdgeschoss.png');
timer = Timer.periodic(
Duration(milliseconds: 500),
(timer) {
refreshImage();
},
);
}
Future loadImage(String path) async {
final data = await rootBundle.load(path);
final bytes = data.buffer.asUint8List();
final image = await decodeImageFromList(bytes);
setState(() {
this.image = image;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Test'),
),
body: Center(
child: image == null
? CircularProgressIndicator()
: Container(
height: 600,
width: 600,
child: FittedBox(
child: SizedBox(
width: image!.width.toDouble(),
height: image!.width.toDouble(),
child: CustomPaint(
painter: ImagePainter(image!),
),
),
)
)
),
);
}
}
class ImagePainter extends CustomPainter {
final ui.Image image;
const ImagePainter(this.image);
#override
void paint(Canvas canvas, Size size) {
//final paint = Paint();
canvas.drawImage(image, Offset.zero, Paint());
final paint = Paint()
..color = Color.fromARGB(255, 15, 182, 253)
..style = PaintingStyle.fill;
canvas.drawCircle(Offset(xList[i], yList[i]), 13, paint);
}
#override
bool shouldRepaint(ImagePainter oldDelegate) {
return false;
}
}