Question

Hello I am learning a bit of droid programming, specifically for class I am trying to make a game. I am trying to use the orientation sensor to get input to use in the game, the problem is that I never get an onchange event to happen. I started running the debugger and found out that register listener always fails and spits back false, this leaves my sensor event listener null, and me confused. since I have been working on this for literally 13 hours I suppose I’ll swallow some pride and ask you guys for help. Here is the code, I have stripped basically everything out from it. I just don’t get sensors.

Thank you all for any help I recieve

      package edu.hiram.cpsc172;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;



@SuppressWarnings("deprecation")
public class GraphView extends View implements SensorEventListener 
{

    private Canvas screen;


    private boolean t = false;
    private float headingAngle;
    private float pitchAngle;
    private float rollAngle;
    private  SensorManager mSensorManager;
    private  Sensor mGyro;
    private SensorEventListener glisten;

    private Context context; // I have no idea what this actually means, but hey why not try? whats the worst that can happen?




       public GraphView(Context con) 
       {
           super(con);
           this.context = con; // so I have a context outside the constructor, it is needed for stuff.
                               // I find it amusing that although I have no clue what this stuff does I am 
                               // recognizing patterns in how context is used.

           //Annoyingly I have to do a few initializations in on draw, I dislike that. 

       }  





       // Called back to draw the view. Also called by invalidate()
       @Override
       protected void onDraw(Canvas canvas) 
       {

               //gives me a canvas object to play with if I want, and draws my background 
              screen = canvas;



            {
               mSensorManager = (SensorManager)context.getSystemService(Context.SENSOR_SERVICE);
                  mGyro = mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION); 
        boolean x = true;        
         x =     mSensorManager.registerListener(glisten, mGyro, Sensor.TYPE_ORIENTATION); //this always returns false, and glisten stays null
                 x = x;
                 x=x; //I realize this does nothing, but it gives me places to set breakpoints, and check the line output
                 x = x;
            }




         try {  
                Thread.sleep(10);  
            } 
         catch (InterruptedException e) 
         {

         }

         invalidate();
      }







       @Override
        public void onSensorChanged(SensorEvent event)     
       {

           {
            headingAngle=event.values[0];
            pitchAngle= event.values[1];
            rollAngle=event.values[2];
           t= true;
           }
          Paint paint = new Paint();
          paint.setColor(Color.WHITE);
           screen.drawText("sensors responded", 100, 100, paint);
    }









    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) 
       {
        // TODO Auto-generated method stub

    }
}

After changing the line the listener gets registered but onSensorChange never fires. I hope editing to ask is right, or is this a new question? Thanks again

Answer 1

You never initialized glisten. But, what you really want to do, since you implement the interface, is to just use this:

  mSensorManager.registerListener(this, mGyro, Sensor.TYPE_ORIENTATION);

See the sample.