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Abhishek Siroha
Abhishek Siroha

Custom Code for Direction Data Using the Magnetometer Sensor

In this article, we will guide you through integrating a custom code in FlutterFlow to get directional data using the magnetometer sensor on your mobile device. This custom code allows your FlutterFlow application to determine the direction relative to true north.

Why Use the Magnetometer Sensor?

The magnetometer sensor in smartphones is used to measure the magnetic field strength in the X, Y, and Z axes. By using these measurements, we can calculate the direction the device is facing, which is useful for navigation, augmented reality, and other applications requiring orientation data.

Step-by-Step Guide

Step 1: Set Up Your FlutterFlow Project

  • Create a new FlutterFlow project or open an existing one where you want to add the custom direction feature.

  • Navigate to the "Actions" section in the FlutterFlow project editor.

Step 2: Add Custom Code

To add custom code to your FlutterFlow project, follow these steps:

  • Go to the "Custom Functions" section:

    • Click on "Custom Code" in the left-hand panel.

    • Select "Add Custom Function."

  • Enter the details for your custom function:

    • Name: directionsDegrees

    • Return Type: Future<double?>

  • Copy and paste the following code into the editor:

// Automatic FlutterFlow imports
import '/backend/supabase/supabase.dart';
import '/flutter_flow/flutter_flow_theme.dart';
import '/flutter_flow/flutter_flow_util.dart';
import '/custom_code/actions/index.dart'; // Imports other custom actions
import '/flutter_flow/custom_functions.dart'; // Imports custom functions
import 'package:flutter/material.dart';
// Begin custom action code
// DO NOT REMOVE OR MODIFY THE CODE ABOVE!

import 'dart:math' as math;
import 'package:sensors_plus/sensors_plus.dart';

Future<double?> directionsDegrees() async {
  // Subscribe to magnetometer events with the desired sampling rate
  final magnetometerStream = magnetometerEventStream();

  try {
    // Listen to the stream for magnetometer events
    final MagnetometerEvent event = await magnetometerStream.first;

    // Calculate direction in radians
    double directionRadians = math.atan2(event.y, event.x);

    // Convert radians to degrees
    double directionDegrees = directionRadians * (180 / math.pi);

    // Adjust angle to be relative to true north
    directionDegrees -= 90.0;
    if (directionDegrees < 0) {
      directionDegrees += 360.0; // Ensure angle is within the range [0, 360)
    }

    return directionDegrees;
  } catch (error) {
    // Handle error gracefully
    print('Error fetching magnetometer data: $error');
    return null;
  }
}

  • Save the custom function.

Step 3: Using the Custom Function in Your FlutterFlow Project

  • Create a UI element (such as a button) to trigger the function.

  • Add an action to the button to call the directionsDegrees function.

  • Display the result in a text widget or use it as needed within your application.

Conclusion

By following these steps, you have successfully integrated a custom code in FlutterFlow to get direction data using the magnetometer sensor in a mobile device. This feature can significantly enhance your application's functionality, especially for navigation and orientation purposes. Feel free to customize and expand upon this code to suit your project's specific needs.

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