OnSensorChanged method is not getting called

Question

I am using stepcounter sensor to detect stepcounts but OnSensorChanged method never gets called.

I have created interface in in PCL-

namespace Pedometer
{
    public interface IStepCounter
    {
        int Steps { get; set; }

        bool IsAvailable();

        void InitSensorService();

        void StopSensorService();
    }
}

Android project code-

[assembly: Dependency(typeof(StepCounter))]
namespace Pedometer.Droid
{
    public class StepCounter : Java.Lang.Object, IStepCounter, ISensorEventListener
    {
        private int StepsCounter = 0;
        private SensorManager sManager;

        public int Steps
        {
            get { return StepsCounter; }
            set { StepsCounter = value; }
        }

        public new void Dispose()
        {
            sManager.UnregisterListener(this);
            sManager.Dispose();
        }

        public void InitSensorService()
        {
            sManager = Android.App.Application.Context.GetSystemService(Context.SensorService) as SensorManager;
            sManager.RegisterListener(this, sManager.GetDefaultSensor(SensorType.StepDetector), SensorDelay.Fastest);

        }

        public void OnAccuracyChanged(Sensor sensor, [GeneratedEnum] SensorStatus accuracy)
        {
            Console.WriteLine("OnAccuracyChanged called");
        }

        public void OnSensorChanged(SensorEvent e)      //This never gets called
        {
            Console.WriteLine(e.ToString());
        }

        public void StopSensorService()
        {
            sManager.UnregisterListener(this);
        }

        public bool IsAvailable()
        {
            return Android.App.Application.Context.PackageManager.HasSystemFeature(Android.Content.PM.PackageManager.FeatureSensorStepCounter) && Android.App.Application.Context.PackageManager.HasSystemFeature(Android.Content.PM.PackageManager.FeatureSensorStepDetector);
        }
    }
}

My mainpage code-

namespace Pedometer
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
            if (DependencyService.Get<IStepCounter>().IsAvailable())
            {
                DependencyService.Get<IStepCounter>().InitSensorService();

                GetCoBut.IsVisible = true;
            }

        }

        private void Button_Clicked(object sender, EventArgs e)
        {
           _actualSteps.Text = DependencyService.Get<IStepCounter>().Steps.ToString();
        }
    }
}

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

You need to add following uses-feature in your AndroidManifest.xml.

   <uses-feature  
          android:name="android.hardware.sensor.stepcounter"  
          android:required="true"/>  
     <uses-feature  
         android:name="android.hardware.sensor.stepdetector"  
         android:required="true"/>  

If you use Android 10 or later, you need to add following permission.

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

And request runtime permission in android.

   if (ContextCompat.CheckSelfPermission(this, Manifest.Permission.ActivityRecognition) != (int)Permission.Granted)  
   {  
                   RequestPermissions(new string[] { Manifest.Permission.ActivityRecognition }, 0);  
   }  

Then I find you sManager.RegisterListener lack of sensor. Here is my editted StepCounter.cs. I test it in my Google pixel, it OnSensorChanged will execute, and could get the steps.

   using Android.App;  
   using Android.Content;  
   using Android.Hardware;  
   using Android.OS;  
   using Android.Runtime;  
   using Android.Views;  
   using Android.Widget;  
   using CustomEntryDemo.Droid;  
   using System;  
   using System.Collections.Generic;  
   using System.Linq;  
   using System.Text;  
   using Xamarin.Forms;  
     
   [ assembly: Dependency(typeof(StepCounter))]  
   namespace CustomEntryDemo.Droid  
   {  
       public class StepCounter : Java.Lang.Object, IStepCounter, ISensorEventListener  
       {  
           private int StepsCounter = 0;  
           private SensorManager sManager;  
     
           public int Steps  
           {  
               get { return StepsCounter; }  
               set { StepsCounter = value; }  
           }  
     
           public new void Dispose()  
           {  
               sManager.UnregisterListener(this);  
               sManager.Dispose();  
           }  
           //private static final int sensorTypeD = Sensor.TYPE_STEP_DETECTOR;  
           //  private static final int sensorTypeC = Sensor.TYPE_STEP_COUNTER;  
           private Sensor mStepCount;  
           private Sensor mStepDetector;  
     
           public void InitSensorService()  
           {  
               sManager = Android.App.Application.Context.GetSystemService(Context.SensorService) as SensorManager;  
                
               mStepCount = sManager.GetDefaultSensor(SensorType.StepDetector);  
               mStepDetector = sManager.GetDefaultSensor(SensorType.StepCounter);  
     
     
               sManager.RegisterListener(this, mStepCount, SensorDelay.Fastest);  
               sManager.RegisterListener(this, mStepDetector, SensorDelay.Fastest);  
     
           }  
     
           public void OnAccuracyChanged(Sensor sensor, [GeneratedEnum] SensorStatus accuracy)  
           {  
               Console.WriteLine("OnAccuracyChanged called");  
           }  
     
           public void OnSensorChanged(SensorEvent e)       
           {  
               Console.WriteLine(e.ToString());  
     
               if (e.Sensor.Type== SensorType.StepCounter) {   
   			//setStepCount(event.values [0]);  
               }  
   		    if (e.Sensor.Type == SensorType.StepDetector) {   
   			    if (e.Values[0]==1.0) {  
                            Steps++;  
                   }  
               }  
     
     
           }  
     
           public void StopSensorService()  
           {  
               sManager.UnregisterListener(this);  
           }  
     
           public bool IsAvailable()  
           {  
               return Android.App.Application.Context.PackageManager.HasSystemFeature(Android.Content.PM.PackageManager.FeatureSensorStepCounter) && Android.App.Application.Context.PackageManager.HasSystemFeature(Android.Content.PM.PackageManager.FeatureSensorStepDetector);  
           }  
       }  
   }  

Best Regards,

Leon Lu

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