UI redesign

open_wearable/android/app/src/main/kotlin/com/example/open_wearable/MainActivity.kt

@@ -1,5 +1,36 @@
 package edu.kit.teco.openWearable
 
+import android.content.Intent
+import android.provider.Settings
 import io.flutter.embedding.android.FlutterActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugin.common.MethodChannel
 
-class MainActivity: FlutterActivity()
+class MainActivity : FlutterActivity() {
+  companion object {
+    private const val SYSTEM_SETTINGS_CHANNEL = "edu.kit.teco.open_wearable/system_settings"
+  }
+
+  override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+    super.configureFlutterEngine(flutterEngine)
+
+    MethodChannel(
+      flutterEngine.dartExecutor.binaryMessenger,
+      SYSTEM_SETTINGS_CHANNEL,
+    ).setMethodCallHandler { call, result ->
+      if (call.method == "openBluetoothSettings") {
+        try {
+          val intent = Intent(Settings.ACTION_BLUETOOTH_SETTINGS).apply {
+            addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+          }
+          startActivity(intent)
+          result.success(true)
+        } catch (_: Exception) {
+          result.success(false)
+        }
+      } else {
+        result.notImplemented()
+      }
+    }
+  }
+}

open_wearable/ios/Runner/AppDelegate.swift

@@ -3,14 +3,40 @@ import UIKit
 
 @main
 @objc class AppDelegate: FlutterAppDelegate {
+  private var sensorShutdownBackgroundTask: UIBackgroundTaskIdentifier = .invalid
+  private var lifecycleChannel: FlutterMethodChannel?
+
+  private func beginSensorShutdownBackgroundTask() {
+    guard sensorShutdownBackgroundTask == .invalid else {
+      return
+    }
+
+    sensorShutdownBackgroundTask = UIApplication.shared.beginBackgroundTask(
+      withName: "SensorShutdown"
+    ) { [weak self] in
+      self?.endSensorShutdownBackgroundTask()
+    }
+  }
+
+  private func endSensorShutdownBackgroundTask() {
+    guard sensorShutdownBackgroundTask != .invalid else {
+      return
+    }
+
+    UIApplication.shared.endBackgroundTask(sensorShutdownBackgroundTask)
+    sensorShutdownBackgroundTask = .invalid
+  }
+
   override func application(
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
   ) -> Bool {    
     let controller: FlutterViewController = window?.rootViewController as! FlutterViewController
-    let channel = FlutterMethodChannel(name: "edu.teco.open_folder", binaryMessenger: controller.binaryMessenger)
+    let openFolderChannel = FlutterMethodChannel(name: "edu.teco.open_folder", binaryMessenger: controller.binaryMessenger)
+    let systemSettingsChannel = FlutterMethodChannel(name: "edu.kit.teco.open_wearable/system_settings", binaryMessenger: controller.binaryMessenger)
+    lifecycleChannel = FlutterMethodChannel(name: "edu.kit.teco.open_wearable/lifecycle", binaryMessenger: controller.binaryMessenger)
 
-    channel.setMethodCallHandler { (call: FlutterMethodCall, result: @escaping FlutterResult) in
+    openFolderChannel.setMethodCallHandler { (call: FlutterMethodCall, result: @escaping FlutterResult) in
       if call.method == "openFolder", let args = call.arguments as? [String: Any], let path = args["path"] as? String {
         guard let url = URL(string: path) else {
           result(FlutterError(code: "INVALID_ARGUMENT", message: "Invalid folder path", details: nil))
@@ -27,6 +53,42 @@ import UIKit
       }
     }
 
+    systemSettingsChannel.setMethodCallHandler { (call: FlutterMethodCall, result: @escaping FlutterResult) in
+      if call.method == "openBluetoothSettings" {
+        guard let settingsUrl = URL(string: UIApplication.openSettingsURLString) else {
+          result(false)
+          return
+        }
+
+        if UIApplication.shared.canOpenURL(settingsUrl) {
+          UIApplication.shared.open(settingsUrl, options: [:]) { success in
+            result(success)
+          }
+        } else {
+          result(false)
+        }
+      } else {
+        result(FlutterMethodNotImplemented)
+      }
+    }
+
+    lifecycleChannel?.setMethodCallHandler { [weak self] (call: FlutterMethodCall, result: @escaping FlutterResult) in
+      guard let self = self else {
+        result(false)
+        return
+      }
+
+      if call.method == "beginBackgroundExecution" {
+        self.beginSensorShutdownBackgroundTask()
+        result(true)
+      } else if call.method == "endBackgroundExecution" {
+        self.endSensorShutdownBackgroundTask()
+        result(true)
+      } else {
+        result(FlutterMethodNotImplemented)
+      }
+    }
+
     GeneratedPluginRegistrant.register(with: self)
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }

open_wearable/lib/apps/heart_tracker/model/band_pass_filter.dart

@@ -8,17 +8,35 @@ class BandPassFilter {
   late final double a0, a1, a2, b1, b2;
   double x1 = 0, x2 = 0;
   double y1 = 0, y2 = 0;
+  bool _isInitialized = false;
 
   BandPassFilter({
     required this.sampleFreq,
     required this.lowCut,
     required this.highCut,
   }) {
-    final centerFreq = sqrt(lowCut * highCut);
-    final bandwidth = highCut - lowCut;
+    final safeSampleFreq =
+        sampleFreq.isFinite && sampleFreq > 0 ? sampleFreq : 50.0;
+    final nyquist = safeSampleFreq / 2.0;
+
+    var safeLow = lowCut;
+    if (!safeLow.isFinite || safeLow <= 0) {
+      safeLow = 0.45;
+    }
+
+    var safeHigh = highCut;
+    if (!safeHigh.isFinite || safeHigh <= safeLow) {
+      safeHigh = safeLow + 0.6;
+    }
+    safeHigh = min(safeHigh, nyquist - 0.05);
+    safeLow = min(safeLow, safeHigh - 0.15);
+    safeLow = max(0.05, safeLow);
+
+    final centerFreq = sqrt(safeLow * safeHigh);
+    final bandwidth = max(0.15, safeHigh - safeLow);
     final q = centerFreq / bandwidth;
 
-    final omega = 2 * pi * centerFreq / sampleFreq;
+    final omega = 2 * pi * centerFreq / safeSampleFreq;
     final alpha = sin(omega) / (2 * q);
 
     final cosOmega = cos(omega);
@@ -32,6 +50,15 @@ class BandPassFilter {
   }
 
   double filter(double x) {
+    if (!_isInitialized) {
+      _isInitialized = true;
+      x1 = x;
+      x2 = x;
+      y1 = 0;
+      y2 = 0;
+      return 0;
+    }
+
     final y = a0 * x + a1 * x1 + a2 * x2 - b1 * y1 - b2 * y2;
     x2 = x1;
     x1 = x;