MobileApp/lib/boxes/compass.dart

import 'dart:async';
import 'dart:ffi';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:flutter_svg/svg.dart';
import 'package:ju_rc_app/lib/boxes.dart';
import 'package:ju_rc_app/lib/sensors.dart';
import 'package:ju_rc_app/lib/serial.dart';

// c-structs
base class GnssLocData extends Struct {
  @Uint8()
  external int type;
  @Uint8()
  external int command;

  @Int32()
  external int X;
  @Int32()
  external int Y;
  @Int32()
  external int Z;
  @Int32()
  external int angle;
}
// end c-structs

class Compass extends JuBox {
  const Compass({super.key});

  @override
  State<StatefulWidget> createState() => _CompassState();
}

class _CompassState extends State<Compass> {
  USerial serial = getSerial();
  late Timer timer;

  int _magX = 0, _magY = 0, _magZ = 0, _magAngle = 0;

  @override
  void initState() {
    super.initState();
    SensorReader.listen(serialListen);
    timer = Timer.periodic(const Duration(milliseconds: 500), (_) async {
      serial.sprintln("<rfSystemSensor>2200", system: true);
    });
  }

  @override
  void dispose() {
    SensorReader.removeListen(serialListen);
    timer.cancel();
    super.dispose();
  }

  void serialListen(int type, int command, Pointer<ArrayCStruct> ptr) {
    if (type != 0x22 || command != 0x00) return;
    var loc = ptr as Pointer<GnssLocData>;
    setState(() {
      _magX = loc.ref.X;
      _magY = loc.ref.Y;
      _magZ = loc.ref.Z;
      int newAngle = loc.ref.angle;
      if (newAngle - _magAngle > 200) newAngle -= 360;
      if (newAngle - _magAngle < -200) newAngle += 360;
      _magAngle = newAngle;
    });
  }

  @override
  Widget build(BuildContext context) => Stack(
        children: [
          SvgPicture.asset('assets/compass.svg'),
          AnimatedRotation(
              turns: _magAngle / 360.0,
              duration: const Duration(milliseconds: 500),
              alignment: Alignment.center, // Rotate around the center
              child: SvgPicture.asset('assets/needle.svg')),
          Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              Text(
                  "x: ${(_magX * 8.0 / 32768.0 * 100.0).toStringAsFixed(2)}µT"),
              Text(
                  "y: ${(_magY * 8.0 / 32768.0 * 100.0).toStringAsFixed(2)}µT"),
              Text(
                  "z: ${(_magZ * 8.0 / 32768.0 * 100.0).toStringAsFixed(2)}µT"),
              Expanded(
                child: Align(
                  alignment: Alignment.bottomLeft,
                  child: FilledButton(
                    child: const Icon(Icons.calculate),
                    onPressed: () {
                      showDialog<String>(
                        context: context,
                        builder: (BuildContext context) => AlertDialog(
                          title: const Text('Callibrate Compass'),
                          content: const Text(
                              'When clicking okay the compass will be calibrated, \ncompletely blocking all radio communication for 10 sec. \nWhile calibrating rotate the sensor in ever direction.'),
                          actions: <Widget>[
                            TextButton(
                              onPressed: () => Navigator.pop(context, 'Cancel'),
                              child: const Text('Cancel'),
                            ),
                            TextButton(
                              onPressed: () {
                                serial.sprintln("<rfSystemSensor>2201",
                                    system: true);
                                Navigator.pop(context, 'OK');
                              },
                              child: const Text('OK'),
                            ),
                          ],
                        ),
                      );
                      //
                    },
                  ),
                ),
              ),
            ],
          ),
          Expanded(
              child: Align(
            alignment: Alignment.topRight,
            child: Text(
                "t: ${(sqrt(_magX * _magX + _magY * _magY + _magZ * _magZ) * 8.0 / 32768.0 * 100.0).toStringAsFixed(2)}µT"),
          ))
        ],
      );
}