How to find direction with flutter compass?

Question

Is there any way to find a specific direction with a Flutter compass. Does that compass indicate a specific long and lat coordinates?

Answer 1

This is the standard code for Qibla compasses I use in my apps to get the offset:

  double getOffsetFromNorth(double currentLatitude, double currentLongitude,
      double targetLatitude, double targetLongitude) {
    var la_rad = radians(currentLatitude);
    var lo_rad = radians(currentLongitude);

    var de_la = radians(targetLatitude);
    var de_lo = radians(targetLongitude);

    var toDegrees = degrees(atan(sin(de_lo - lo_rad) /
        ((cos(la_rad) * tan(de_la)) - (sin(la_rad) * cos(de_lo - lo_rad)))));
    if (la_rad > de_la) {
      if ((lo_rad > de_lo || lo_rad < radians(-180.0) + de_lo) &&
          toDegrees > 0.0 &&
          toDegrees <= 90.0) {
        toDegrees += 180.0;
      } else if (lo_rad <= de_lo &&
          lo_rad >= radians(-180.0) + de_lo &&
          toDegrees > -90.0 &&
          toDegrees < 0.0) {
        toDegrees += 180.0;
      }
    }
    if (la_rad < de_la) {
      if ((lo_rad > de_lo || lo_rad < radians(-180.0) + de_lo) &&
          toDegrees > 0.0 &&
          toDegrees < 90.0) {
        toDegrees += 180.0;
      }
      if (lo_rad <= de_lo &&
          lo_rad >= radians(-180.0) + de_lo &&
          toDegrees > -90.0 &&
          toDegrees <= 0.0) {
        toDegrees += 180.0;
      }
    }
    return toDegrees;
  }

then you add the offset to the flutter_compass rotation to get the offset for each sensor update and apply the result to the special header.