Android - Accelerometer

Community Forums/General Help/Android - Accelerometer

EOF	(Posted 2011) [#1]

This is call for help, aimed at any Android dev guys in the house

What I am trying to do is create a class for the Accelerometer which I can later drop into projects without too much effort.
Hopefully this is something which can be used with monkey

The basics will be

Accelerometer accel = new Accelerometer()
// accel.x , accel.y , accel.z

The accelerometer readings will always be accessible by reading the x,y,z values contained within the class

What I have so far crashes horribly (FORCE CLOSE). It seems to be down to either the accelerometer code, or the display setup

Can you guys make sense of this?

TEST CODE

package example.AccelTest;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Display;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

public class AccelTest extends Activity{
	// init variables
	DrawView drawView;
	Paint paint = new Paint();

	private long mTimerDelay = 10;
	// for the display size
	Display display; 
	public int width;
	public int height;

	// new accelerometer handler
	public Accelerometer accel;
	
    // app-specific variables
	public float ballX , ballY;
	public int BallSize = 26;
	
	// set up the main timer
	public RefreshHandler mTimerHandler;
	
	class RefreshHandler extends Handler {
		private long delaytime;
		
		@Override
		public void handleMessage(Message msg) {
			drawView.invalidate();
			mTimerHandler.sleep(mTimerDelay); // issue another timer message
		}
				
		public void sleep(long delayMillis) {
			this.removeMessages(0);
			sendMessageDelayed(obtainMessage(0), delayMillis);
		}
		public void Stop(){this.removeMessages(0);}
		public void Start(){this.sleep(delaytime);}
	}

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		// full screen
		fullScreen(); stayawake();
		
		// set display
		drawView = new DrawView(this);
		setContentView(drawView); // R.layout.main
		drawView.requestFocus();

		// grab the screen size
		display=getWindowManager().getDefaultDisplay();
		width = display.getWidth();
		height = display.getHeight();
		
		// kickstart the timer
		mTimerHandler=new RefreshHandler();
		mTimerHandler.delaytime=12;
		mTimerHandler.Start();
		
		// app variable settings
		ballX=width/2 ; ballY=height/2;
		
		accel = new Accelerometer(display);
	}

    protected void onResume() {
        super.onResume();
        accel.Start();
       	mTimerHandler.Start();
    }

    protected void onPause() {
        super.onPause();
        accel.Stop();
        mTimerHandler.Stop();
    }
	
    protected void onDestroy() {
        super.onDestroy();
        accel.Stop();
        mTimerHandler.Stop();
    }

    
	public class DrawView extends View {

		public DrawView(Context context) {
			super(context);
			setFocusable(true);
			setFocusableInTouchMode(true);
			paint.setColor(Color.BLUE);
			paint.setAntiAlias(false);
		}

		// main draw routine
		@Override
		public void onDraw(Canvas canvas) {
			// Clear the canvas
			paint.setColor(Color.BLACK);
			canvas.drawPaint(paint);
			// crosshairs (for display center)
			paint.setColor(Color.DKGRAY);
			canvas.drawLine(width/2, 0, width/2, height, paint);
			canvas.drawLine(0, height/2, width, height/2, paint);
			// move ball
			ballX-=accel.x ; ballY+=accel.y;
			if (ballX<BallSize) ballX=BallSize;
			if (ballX>(width-BallSize)) ballX=width-BallSize;
			if (ballY<BallSize) ballY=BallSize;
			if (ballY>(height-BallSize)) ballY=height-BallSize;
			// render ball
			paint.setColor(Color.GREEN);
			canvas.drawCircle(ballX, ballY, BallSize, paint);
			// text to indicate accelerometer values
			paint.setTextSize(32);
			paint.setColor(Color.CYAN);
			canvas.drawText("accX: "+String(accel.x) , 10, height-60, paint);
			canvas.drawText("accY: "+String(accel.y) , 10, height-20, paint);
			canvas.drawText("accZ: "+String(accel.z) , 10, height-120, paint);
		}

		private String String(float v) {return String.valueOf(v);}
		
	}

	void fullScreen() {
		final int flag = WindowManager.LayoutParams.FLAG_FULLSCREEN;
		getWindow().setFlags(flag, flag);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
	}

	void stayawake() {
		final int flag = WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
		getWindow().setFlags(flag, flag);
	}
	
}

ACCELEROMETER CODE

package example.AccelTest;

import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.view.Display;
import android.view.Surface;

public class Accelerometer extends Activity {
    private final SensorManager mSensorManager;
    private final Sensor mSensor;
    private Display mDisplay;
    
    public float x,y,z;
       
    public Accelerometer(Display mDisp){
    	mDisplay=mDisp;
    	mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    	mSensor=mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
	}
    
    public void Stop(){
    	mSensorManager.unregisterListener(accelListener);
    }
    
    public void Start(){
    	mSensorManager.registerListener(accelListener, mSensor, SensorManager.SENSOR_DELAY_UI);
    }

    protected SensorEventListener accelListener = new SensorEventListener(){
    	
    	
    	@Override
        public void onSensorChanged(SensorEvent event) {
            if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER) return;
            z=event.values[2];
            switch (mDisplay.getRotation()) {
                case Surface.ROTATION_0:
                    x = event.values[0];
                    y = event.values[1];
                    break;
                case Surface.ROTATION_90:
                	x = -event.values[1];
                	y = event.values[0];
                    break;
                case Surface.ROTATION_180:
                	x = -event.values[0];
                	y = -event.values[1];
                    break;
                case Surface.ROTATION_270:
                	x = event.values[1];
                	y = -event.values[0];
                    break;
            }
        }
        
    	@Override
        public void onAccuracyChanged(Sensor sensor, int accuracy) {}
    };
}

Last edited 2011

matt!

(Posted 2011) [#2]

Have you tried this?

Android - SensorManager
http://blog.androgames.net/85/android-accelerometer-tutorial/

Here are the accelerator functions that may be used for the other supported devices:

iPhone - UIAccelerometer
http://blancer.com/tutorials/i-phone/110706/how-to-make-an-iphone-app-–-part-5-the-accelerometer/

HTML5 - DeviceOrientation
http://www.mobilexweb.com/blog/safari-ios-accelerometer-websockets-html5 (example linked to from that page)
http://dev.w3.org/geo/api/spec-source-orientation.html

Flash - flash.sensors.Accelerometer
http://help.adobe.com/en_US/FlashPlatform/beta/reference/actionscript/3/flash/sensors/Accelerometer.html

XNA - Accelerometer
http://www.jason-mitchell.com/index.php/2009/10/24/zune-hd-accelerometer/

Cheers,
matt

Dabhand

(Posted 2011) [#3]

http://blog.androgames.net/85/android-accelerometer-tutorial/

Any good?

Dabz