Help to CustomPainter(controller.zoneOffset) repaint when List<OffSet> zoneOffset added by GestureDetector

[haiph-dev]

Dear Getx community,

Sorry for my bad English, I tried to repaint CustomPainter(controller.zoneOffset) whenever List zoneOffset added by GestureDetector as below code. But I found it only repaint if I have Text(controller.zoneOffset.toString()) to force rebuild Widget Tree.

Please help to advise what I missed, thank you for support,

class CameraDetailController extends GetxController {
  List<Offset> zoneOffset = <Offset>[].obs;
}

class CameraDetailPage extends GetView<CameraDetailController> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Camera')),
      body: SingleChildScrollView(
        child: Obx(
          () => Column(
            children: [
              //Text(controller.zoneOffset.toString()),
              CustomPaint(
                  foregroundPainter: ZonePainter(controller.zoneOffset),
                  child: GestureDetector(
                    child: Image.memory(controller.image.value),
                    onTapDown: (details) {
                      controller.zoneOffset.add(details.localPosition);
                    },
                  )),
            ],
          ),
        ),
      ),
    );
  }
}