Mobile Programming (MP)

Mobile Programming

Mobile Sensors

Lecturer: Ali Najimi
Faculty of Computer Engineering
Sharif University of Technology
Fall 2027

Accelerometer Gyroscope GPS Biometrics Camera Proximity Light Compass

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Table of Contents

  1. Introduction to Mobile Sensors
  2. Sensor Categories Overview
  3. Motion Sensors — Accelerometer and Gyroscope
  4. Motion Sensors — Magnetometer and Gravity
  5. Position Sensors — GPS and Location
  6. Position Sensors — Proximity and Step Counter
  7. Environmental Sensors — Light, Pressure, Humidity
  8. Biometric Sensors — Fingerprint and Face ID
  9. Camera and Microphone Sensors
  10. Connectivity Sensors — NFC, Bluetooth, Wi-Fi
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Table of Contents

  1. Flutter Sensor Packages Overview
  2. sensors_plus — Motion and Position
  3. geolocator — GPS and Location
  4. local_auth — Biometric Authentication
  5. Battery and Performance Considerations
  6. Exercise: Sensor Dashboard and Live Wallpaper
  7. Exercise: Bank Card App
  8. Summary and Key Takeaways
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Introduction to Mobile Sensors

Modern smartphones contain 10-20+ sensors that enable context-aware experiences.

Why sensors matter:

  • Context awareness — Apps adapt to user environment (dark mode from light sensor).
  • Health and fitness — Step counting, heart rate, sleep tracking.
  • Navigation — GPS + compass for turn-by-turn directions.
  • Security — Fingerprint and face recognition for authentication.
  • Gaming — Tilt controls via accelerometer and gyroscope.
  • AR/VR — Camera + motion sensors for immersive experiences.

A modern flagship phone has more sensors than a 1990s space probe.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Sensor Categories Overview

Category Sensors Primary Use
Motion Accelerometer, Gyroscope, Gravity, Linear Acceleration Device movement, tilt, rotation
Position GPS, Magnetometer (Compass), Proximity Location, heading, near/far
Environmental Light, Pressure (Barometer), Temperature, Humidity Ambient conditions
Biometric Fingerprint, Face ID/Iris Authentication, security
Media Camera (RGB/Depth/IR), Microphone Photos, video, audio, AR
Connectivity NFC, Bluetooth, Wi-Fi, Cellular Proximity, communication
Health Heart Rate, SpO2, Step Counter, Body Temperature Fitness, medical
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Motion Sensors — Accelerometer

The accelerometer measures acceleration forces (including gravity) on 3 axes.

How it works:

  • MEMS (Micro-Electro-Mechanical Systems) technology.
  • Measures acceleration in m/s2 along X, Y, Z axes.
  • At rest, reports ~9.81 m/s2 upward (gravity).

Use cases:

  • Screen rotation (portrait / landscape).
  • Shake detection (undo action).
  • Tilt-based game controls.
  • Fall detection (Apple Watch).
  • Pedometer (step counting).

Note: Accelerometer data includes gravity. linear_acceleration: gravity-free data.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Motion Sensors — Accelerometer in Flutter

Package: sensors_plus

# pubspec.yaml
dependencies:
  sensors_plus: ^6.0.1

import 'package:sensors_plus/sensors_plus.dart';

// Listen to accelerometer events
accelerometerEvents.listen((AccelerometerEvent event) {
  print('X: ${event.x}, Y: ${event.y}, Z: ${event.z}');
  // At rest on table: X~0, Y~0, Z~9.81
});

Tip: Sensor events fire at high frequency (~100-200 Hz). Throttle updates for UI.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Motion Sensors — Gyroscope

The gyroscope measures angular velocity (rotation speed) around 3 axes.

How it works:

  • Measures rotation rate in rad/s around X, Y, Z axes.
  • Coriolis effect on vibrating MEMS structure.
  • Does NOT measure absolute angle — only rotation speed.

Use cases:

  • Camera image stabilization.
  • Gesture recognition (flick, twist).
  • 3D game controls (steering, aiming).
  • Drone stabilization.
  • Augmented Reality (AR) head tracking.

Combine with accelerometer for full 6-axis orientation (sensor fusion).

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Motion Sensors — Gyroscope in Flutter

import 'package:sensors_plus/sensors_plus.dart';

// Rotation rate in rad/s
gyroscopeEvents.listen((GyroscopeEvent event) {
  print('RotX: ${event.x}, RotY: ${event.y}, RotZ: ${event.z}');
});

// Gravity sensor (gravity direction only)
gravityEvents.listen((GravityEvent event) {
  print('Gravity X: ${event.x}, Y: ${event.y}, Z: ${event.z}');
});

// Linear acceleration (no gravity)
linearAccelerationEvents.listen((LinearAccelerationEvent event) {
  print('Accel X: ${event.x}, Y: ${event.y}, Z: ${event.z}');
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Motion Sensors — Magnetometer

The magnetometer measures the Earth's magnetic field — acts as a digital compass.

How it works:

  • Measures magnetic field strength in uT (microtesla) on 3 axes.
  • Hall effect or magnetoresistive sensor.
  • Earth's magnetic field is approximately 25-65 uT.

Use cases:

  • Compass apps (direction/heading).
  • Map orientation (rotate map to face direction).
  • Metal detection (field disturbance).
  • Indoor navigation.

Warning: Keep away from magnets and speakers — they distort readings. Calibrate by moving phone in a figure-8 pattern.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Motion Sensors — Magnetometer in Flutter

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

magnetometerEvents.listen((MagnetometerEvent event) {
  print('Mag X: ${event.x}, Y: ${event.y}, Z: ${event.z}');

  // Calculate compass heading (azimuth)
  final heading = atan2(event.y, event.x) * (180 / pi);
  final normalized = heading < 0 ? heading + 360 : heading;
  print('Compass heading: ${normalized.toStringAsFixed(1)} deg');
});

Full orientation (rotation vector):

rotationVectorEvents.listen((RotationVectorEvent event) {
  print('Rot: X=${event.x}, Y=${event.y}, Z=${event.z}');
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — GPS and Location

GPS (Global Positioning System) provides outdoor location using satellite signals.

How it works:

  • Triangulates position from 4+ satellites.
  • Accuracy: 3-5 meters (open sky), worse indoors.
  • Cold start: ~30s to get first fix.
  • Assisted GPS (A-GPS) uses cell towers + Wi-Fi for faster fix.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — GPS and Location

Flutter package: geolocator

dependencies:
  geolocator: ^13.0.2

Other location sources:

  • Wi-Fi positioning — Indoor, ~10-50m accuracy.
  • Cell tower triangulation — ~100-500m accuracy.
  • BLE beacons — Indoor, ~1-5m accuracy.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — GPS in Flutter

import 'package:geolocator/geolocator.dart';
// Check and request permission
LocationPermission perm = await Geolocator.checkPermission();
if (perm == LocationPermission.denied) {
  perm = await Geolocator.requestPermission();
}
// Get current position
Position pos = await Geolocator.getCurrentPosition(
  desiredAccuracy: LocationAccuracy.high,
);
print('Lat: ${pos.latitude}, Lon: ${pos.longitude}');
print('Altitude: ${pos.altitude}m, Speed: ${pos.speed}m/s');
// Stream location updates
Geolocator.getPositionStream(
  locationSettings: LocationSettings(
    accuracy: LocationAccuracy.high,
    distanceFilter: 10, // Update every 10 meters
  ),
).listen((Position p) {
  print('New pos: ${p.latitude}, ${p.longitude}');
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — Geocoding

Convert between coordinates and addresses using geocoding.

dependencies:
  geocoding: ^3.0.0

import 'package:geocoding/geocoding.dart';

// Coordinates -> Address (Reverse Geocoding)
List<Placemark> placemarks = await placemarkFromCoordinates(
  35.6892, 51.3890, // Tehran
);
print(placemarks.first.street);    // Street name
print(placemarks.first.locality);  // City
print(placemarks.first.country);   // Country

// Address -> Coordinates (Forward Geocoding)
List<Location> locations = await locationFromAddress(
  "Sharif University of Technology, Tehran",
);
print('Lat: ${locations.first.latitude}');
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — Proximity Sensor

The proximity sensor detects if an object is near the phone (binary: near/far).

How it works:

  • Infrared LED + IR detector.
  • Detects objects within ~5 cm.
  • Binary output: 0 (near) or 1 (far).

Primary use case:

  • Turn off screen during phone calls (ear proximity).
  • Pocket detection (lock screen).
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — Proximity Sensor

Flutter package: proximity_sensor

import 'package:proximity_sensor/proximity_sensor.dart';

ProximitySensor.events.listen((bool isNear) {
  if (isNear) {
    print('Object detected near screen');
  } else {
    print('No object near screen');
  }
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — Step Counter

The step counter uses accelerometer data to detect walking steps.

How it works:

  • Hardware step detector (Android TYPE_STEP_COUNTER).
  • Persists across sleep — counts total steps since boot.
  • Uses pattern recognition on acceleration peaks.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Position Sensors — Step Counter

Flutter packages:

dependencies:
  pedometer: ^0.0.6        # Step count + activity recognition
  # OR
  health: ^11.0.0           # Apple Health / Google Fit integration

import 'package:pedometer/pedometer.dart';

Pedometer.stepCountStream.listen((StepCount count) {
  print('Steps: ${count.steps}');
});

Pedometer.activityStream.listen((ActivityEvent activity) {
  print('Activity: ${activity.type}'); // WALKING, RUNNING, STILL
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Environmental Sensors — Light Sensor

The ambient light sensor measures light intensity in lux (lx).

How it works:

  • Photodiode that measures visible light intensity.
  • Range: 0-65,000+ lux.
  • Dark room: ~50 lux, Office: ~300-500 lux, Direct sun: ~100,000 lux.

Use cases:

  • Auto-brightness — Adjust screen brightness.
  • Camera exposure — Auto ISO/shutter speed.
  • Smart home — Turn on lights when dark.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Environmental Sensors — Light Sensor

Flutter package: light_sensor

import 'package:light_sensor/light_sensor.dart';

LightSensor.luxStream.listen((int lux) {
  print('Ambient light: $lux lux');
  if (lux < 50) {
    print('Dark environment');
  } else if (lux > 10000) {
    print('Bright sunlight');
  }
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Environmental Sensors — Barometer

The barometer measures atmospheric pressure for altitude estimation.

How it works:

  • Measures air pressure in hPa (hectopascals).
  • Normal sea-level pressure: 1013.25 hPa.
  • Can detect altitude changes of +/-1 meter.

Use cases:

  • Floor detection — Which floor of a building you're on.
  • Weather prediction — Falling pressure = incoming storm.
  • Altitude for GPS — Improves GPS vertical accuracy.
  • Hiking/fitness apps — Elevation tracking.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Environmental Sensors — Barometer

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

barometerEvents.listen((BarometerEvent event) {
  print('Pressure: ${event.pressure} hPa');
  final alt = 44330 * (1 - pow(event.pressure / 1013.25, 0.1903));
  print('Estimated altitude: ${alt.toStringAsFixed(1)}m');
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Environmental Sensors — Temperature and Humidity

Some devices include temperature and humidity sensors.

Temperature sensor:

  • Measures ambient temperature in degrees Celsius.
  • Found in some Samsung, Motorola devices.
  • Use case: Weather apps, smart home.

Humidity sensor:

  • Measures relative humidity in %RH.
  • Combined with temperature for dew point calculation.
  • Use case: Comfort index, weather apps.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Environmental Sensors — Temperature and Humidity

Flutter access: Platform channels (not all devices have these).

// Android: SensorManager.getDefaultSensor(TYPE_AMBIENT_TEMPERATURE)
// iOS: CMHumiditySensor (limited availability)
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Biometric Sensors — Fingerprint

Fingerprint sensors provide biometric authentication using fingerprint patterns.

How it works:

  • Capacitive — Most common. Uses tiny capacitor arrays to map ridges/valleys.
  • Ultrasonic (Samsung) — Uses sound waves for 3D fingerprint map.
  • Optical (under-display) — Uses light to capture fingerprint image.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Biometric Sensors — Fingerprint

Flutter package: local_auth

dependencies:
  local_auth: ^2.3.0

Android manifest:

<uses-permission android:name="android.permission.USE_BIOMETRIC" />

iOS Info.plist:

<key>NSFaceIDUsageDescription</key>
<string>This app needs biometric access for authentication</string>
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Biometric Sensors — Fingerprint in Flutter

import 'package:local_auth/local_auth.dart';
final localAuth = LocalAuthentication();
// Check if device supports biometrics
bool canAuth = await localAuth.canCheckBiometrics;
// OR
bool isSupported = await localAuth.isDeviceSupported();
// Get available biometric types
List<BiometricType> availableBiometrics =
    await localAuth.getAvailableBiometrics();
// [BiometricType.fingerprint, BiometricType.face, BiometricType.weak]
// Authenticate with fingerprint
bool authenticated = await localAuth.authenticate(
  localizedReason: 'Please authenticate to access your data',
  options: AuthenticationOptions(
    stickyAuth: true,
    biometricOnly: true, // No fallback to PIN
  ),
);
if (authenticated) {
  print('User authenticated successfully!');
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Biometric Sensors — Face ID

Face ID (Apple) and Face Unlock (Android) use facial recognition.

How it works (Apple Face ID):

  • TrueDepth camera projects 30,000 IR dots onto face.
  • IR camera captures the dot pattern.
  • Neural engine matches against stored facial data.
  • Works in dark, with glasses, hats, and masks.

How it works (Android Face Unlock):

  • Front camera + ML-based face detection.
  • Some devices use IR (like Apple), others use RGB only.
  • Less secure than fingerprint for payments.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Biometric Sensors — Face ID

Flutter usage: Same local_auth package — the OS chooses the method.

// Same code works for both fingerprint and face
bool auth = await localAuth.authenticate(
  localizedReason: 'Scan your face or fingerprint',
  options: AuthenticationOptions(biometricOnly: true),
);
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Camera Sensors

Modern phones have multiple cameras with various sensor types.

Camera types:

  • Wide — Standard camera (24-35mm equivalent).
  • Ultrawide — 120+ degree field of view.
  • Telephoto — 2-10x optical zoom.
  • Depth (ToF) — Time-of-flight for depth mapping.
  • IR — Infrared for Face ID, night vision.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Camera Sensors

Flutter package: camera

dependencies:
  camera: ^0.11.0

import 'package:camera/camera.dart';

// Get available cameras
final cameras = await availableCameras();
final firstCamera = cameras.first;

// Create controller
final controller = CameraController(
  firstCamera,
  ResolutionPreset.high,
  enableAudio: false,
);
await controller.initialize();

// Take photo
final image = await controller.takePicture();
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Camera Sensors — AR and Depth

Depth sensors enable Augmented Reality and 3D scanning.

Technologies:

  • LiDAR (Apple iPad Pro, iPhone Pro) — Light detection and ranging.
  • ToF (Samsung, others) — Time-of-flight infrared.
  • Stereo vision — Dual camera depth estimation.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Camera Sensors — AR and Depth

Flutter packages for AR:

dependencies:
  ar_flutter_plugin: ^0.7.3    # ARCore/ARKit wrapper
  # OR
  model_viewer_plus: ^1.0.0    # 3D model viewer

Use cases:

  • AR gaming — Pokemon Go, furniture placement (IKEA).
  • Measurement — Measure distances with camera.
  • 3D scanning — Create 3D models of objects.
  • Navigation — AR walking directions.
  • Virtual try-on — Glasses, clothes, makeup.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Microphone Sensor

The microphone captures audio for various applications.

How it works:

  • MEMS microphone converts sound waves to electrical signals.
  • Sample rate: up to 48 kHz (CD quality).
  • Multiple microphones for noise cancellation and spatial audio.

Flutter package: record or flutter_sound

dependencies:
  record: ^5.1.0        # Audio recording
  # OR
  flutter_sound: ^9.0.0 # Recording + playback
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Microphone Sensor

Use cases:

  • Voice recording and notes.
  • Speech recognition (STT).
  • Music detection (Shazam-like).
  • Environmental sound classification.
  • Voice commands.

Important: Always request microphone permission before recording.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — NFC

NFC (Near Field Communication) enables short-range wireless communication.

How it works:

  • Range: ~4 cm (touch-to-share).
  • Frequency: 13.56 MHz.
  • Data rate: up to 424 kbps.
  • Two modes: read/write and peer-to-peer.

Use cases:

  • Contactless payments — Apple Pay, Google Pay.
  • Transit cards — Tap to ride.
  • Smart posters — Tap for info.
  • Access cards — Hotel rooms, offices.
  • Android Beam (deprecated) / AirDrop alternative.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — NFC

Flutter package: nfc_manager

dependencies:
  nfc_manager: ^3.5.0
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — NFC in Flutter

import 'package:nfc_manager/nfc_manager.dart';
// Check NFC availability
bool isAvailable = await NfcManager.instance.isAvailable();
// Start NFC session
NfcManager.instance.startSession(
  onDiscovered: (NfcTag tag) async {
    print('Tag discovered: ${tag.data}');
    // Read NDEF records
    final ndef = Ndef.from(tag);
    if (ndef != null) {
      for (var record in ndef.cachedMessage!.records) {
        print('Payload: ${String.fromCharCodes(record.payload)}');
      }
    }
    // Write NDEF record
    final newMessage = NdefMessage([
      NdefRecord.createText('Hello NFC!'),
    ]);
    await ndef.write(newMessage);
  },
);
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — Bluetooth

Bluetooth enables short-to-medium range wireless communication.

Bluetooth versions:

  • Classic (BR/EDR) — Headphones, speakers, file transfer. Range: ~10m.
  • BLE (Bluetooth Low Energy) — IoT, wearables, beacons. Range: ~100m.
  • Bluetooth 5.0+ — 2x speed, 4x range, 8x broadcast capacity.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — Bluetooth

Flutter packages:

dependencies:
  flutter_blue_plus: ^1.32.0   # BLE communication
  # OR
  bluetooth_enable: ^0.0.1     # Enable Bluetooth

import 'package:flutter_blue_plus/flutter_blue_plus.dart';

// Scan for BLE devices
FlutterBluePlus.startScan(timeout: Duration(seconds: 10));
FlutterBluePlus.scanResults.listen((results) {
  for (ScanResult r in results) {
    print('${r.device.platformName}: ${r.rssi} dBm');
  }
});
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — Wi-Fi and Cellular

Wi-Fi sensing and cellular provide additional context.

Wi-Fi:

  • RSSI (signal strength) for proximity estimation.
  • Wi-Fi RTT (Round-Trip Time) for indoor positioning (~1m accuracy).
  • Wi-Fi Direct for peer-to-peer communication.

Cellular:

  • Cell tower ID for coarse location.
  • Signal strength for coverage mapping.
  • 5G enables new AR/VR use cases.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Connectivity Sensors — Wi-Fi and Cellular

Flutter packages:

dependencies:
  connectivity_plus: ^6.0.3    # Network status
  network_info_plus: ^6.0.0    # Wi-Fi info

import 'package:connectivity_plus/connectivity_plus.dart';

// Check connectivity
final result = await Connectivity().checkConnectivity();
if (result.contains(ConnectivityResult.wifi)) {
  print('Connected to Wi-Fi');
} else if (result.contains(ConnectivityResult.mobile)) {
  print('Connected to cellular');
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Flutter Sensor Packages Overview

Motion and Position

  • sensors_plus — Accelerometer, gyroscope, magnetometer, barometer
  • geolocator — GPS location
  • geocoding — Address to coordinates
  • proximity_sensor — Proximity detection
  • pedometer — Step counting
  • flutter_compass — Compass heading

Environmental

  • light_sensor — Ambient light
  • battery_plus — Battery level/status

Biometric and Security

  • local_auth — Fingerprint and Face ID
  • nfc_manager — NFC read/write
  • secure_application — Screen capture prevention

Media

  • camera — Camera access
  • record — Audio recording

Connectivity

  • flutter_blue_plus — BLE
  • connectivity_plus — Network status
  • network_info_plus — Wi-Fi info
  • nearby_connections — P2P communication
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

sensors_plus — Complete API

The sensors_plus package provides access to all motion and environmental sensors.

import 'package:sensors_plus/sensors_plus.dart';

// All available sensor streams:
accelerometerEvents        // Acceleration + gravity (m/s2)
gyroscopeEvents            // Rotation rate (rad/s)
magnetometerEvents         // Magnetic field (uT)
gravityEvents              // Gravity vector only (m/s2)
linearAccelerationEvents   // Acceleration without gravity (m/s2)
rotationVectorEvents       // Device orientation (quaternion)
barometerEvents            // Atmospheric pressure (hPa)

// Each event provides x, y, z values:
accelerometerEvents.listen((event) {
  // event.x, event.y, event.z
});
barometerEvents.listen((event) {
  // event.pressure
});

Note: Not all sensors are available on all devices. Always check availability.

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

geolocator — Complete API

import 'package:geolocator/geolocator.dart';

// Permission management
LocationPermission perm = await Geolocator.checkPermission();
perm = await Geolocator.requestPermission();
// PermissionStatus: denied, deniedForever, whileInUse, always

// Current position (one-shot)
Position pos = await Geolocator.getCurrentPosition(
  locationSettings: LocationSettings(
    accuracy: LocationAccuracy.high,
    timeLimit: Duration(seconds: 10),
  ),
);

// Position stream (continuous)
Stream<Position> stream = Geolocator.getPositionStream(
  locationSettings: LocationSettings(
    accuracy: LocationAccuracy.high,
    distanceFilter: 5, // min distance between updates
  ),
);

// Distance between two points
double distance = Geolocator.distanceBetween(
  35.6892, 51.3890, // Tehran
  32.6539, 51.6660, // Isfahan
);
print('Distance: ${(distance / 1000).toStringAsFixed(0)} km');
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

local_auth — Biometric Authentication

import 'package:local_auth/local_auth.dart';
import 'package:local_auth/error_codes.dart' as auth_error;

final localAuth = LocalAuthentication();

// Check device capability
bool canCheck = await localAuth.canCheckBiometrics;
bool deviceSupported = await localAuth.isDeviceSupported();

// List available biometrics
List<BiometricType> biometrics = await localAuth.getAvailableBiometrics();
// BiometricType.fingerprint
// BiometricType.face
// BiometricType.iris (rare)
// BiometricType.weak (Android class 2 biometry)

// Authenticate
try {
  bool auth = await localAuth.authenticate(
    localizedReason: 'Please verify your identity',
    options: AuthenticationOptions(
      stickyAuth: true,       // Resume after app switch
      biometricOnly: false,   // Allow PIN fallback
      useErrorDialogs: true,  // Show error dialogs
    ),
  );
} on PlatformException catch (e) {
  if (e.code == auth_error.notAvailable) {
    // No biometrics enrolled
  }
}
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Battery and Performance Considerations

Sensor usage impacts battery life significantly.

Best Practices:

  • Unsubscribe from sensor streams when not needed.
  • Use distanceFilter for GPS (avoid continuous updates).
  • Lower sensor accuracy when high precision is not needed.
  • Batch sensor readings for processing.
  • Use WorkManager for background sensor tasks.

Battery Impact by Sensor:

Sensor Battery Drain
GPS (high accuracy) High
GPS (low accuracy) Medium
Accelerometer Low
Gyroscope Low-Medium
Bluetooth scan Medium
NFC Very Low
Camera High

Rule: Only subscribe to sensors when your screen is visible. Unsubscribe in dispose().

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Exercise: Sensor Dashboard, Live Wallpaper

Goal: Build a Flutter app that demonstrates ALL sensors with a parallax live wallpaper.

  1. Parallax wallpaper — Background moves based on accelerometer/gyroscope.
  2. Biometric lock — Fingerprint/Face ID to unlock sensor dashboard.
  3. Compass — Real-time compass using magnetometer.
  4. GPS map — Show current location on a map.
  5. Light meter — Display ambient light level with auto-theme.
  6. Step counter — Count steps using pedometer.
  7. Proximity detector — Detect when phone is near object.
  8. Barometer/altitude — Show pressure and estimated altitude.
  9. NFC reader — Read NFC tags.
  10. Shake detection — Detect phone shake gesture.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Exercise: Encrypted Bank Card App

Objective: Build a notes app with encrypted storage.

Requirements:

  1. SQLite database with sqflite.
  2. Notes model with card number, cvv2, exp.
  3. CRUD operations via CardRepository.
  4. Encryption per card using flutter_secure_storage.
  5. Search functionality.
  6. NFC.
  7. Biometric Lock.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Summary: Key Takeaways

Sensor Types

  • Motion: Accelerometer, Gyroscope, Magnetometer, Gravity, Linear Acceleration.
  • Position: GPS, Proximity, Step Counter.
  • Environmental: Light, Barometer, Temperature, Humidity.
  • Biometric: Fingerprint, Face ID, Iris.
  • Media: Camera (RGB/Depth/IR), Microphone.
  • Connectivity: NFC, BLE, Wi-Fi, Cellular.

Best Practices

  • Always check sensor availability before subscribing.
  • Unsubscribe from sensors in dispose().
  • Request runtime permissions properly.
  • Use sensor fusion for better accuracy.
  • Throttle high-frequency sensor updates for UI.
  • Consider battery impact of continuous sensing.
  • Handle missing sensors gracefully (fallback UI).
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Summary: Key Takeaways

Key Packages

  • sensors_plus — All motion sensors.
  • geolocator + geocoding — GPS.
  • local_auth — Biometrics.
  • nfc_manager — NFC.
  • flutter_blue_plus — BLE.
  • light_sensor — Ambient light.
  • camera — Camera access.

Exercise Highlights

  • Parallax wallpaper using accelerometer.
  • Biometric lock with fingerprint/Face ID.
  • Real-time compass with magnetometer.
  • GPS location with geocoding.
  • Auto-theme with light sensor.
  • NFC tag reader.
  • Shake detection gesture.
  • Using secure storage in a real life app.
Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

References

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

References

Sharif University of Technology • Fall 2027 • Ali Najimi
Mobile Programming (MP)

Thank You! 🙌

Questions?

"I shook my phone to undo a bug,
then the compass pointed to my ex's house,
and the proximity sensor said 'too close.'
Sensors know too much."
— A developer after building a sensor app

Sharif University of Technology • Fall 2027 • Ali Najimi