Detect Shaking

By comparing previous and current reading of build-in accelerometer sensor, shaking of android device can be detected.



In this exercise, three SeekBar is used to adjust the sensitive of x, y, z. The changing rate are compare with the sensitive to detect shaking.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView  
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="@string/hello"
    />
<SeekBar
 android:id="@+id/xsensitive"   
 android:layout_width="fill_parent"   
 android:layout_height="wrap_content"   
 android:max="100"  
 />  
<TextView
 android:id="@+id/x"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<TextView
 android:id="@+id/xrate"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<TextView
 android:id="@+id/xstate"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<SeekBar
 android:id="@+id/ysensitive"   
 android:layout_width="fill_parent"   
 android:layout_height="wrap_content"   
 android:max="100"  
 />  
<TextView
 android:id="@+id/y"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<TextView
 android:id="@+id/yrate"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<TextView
 android:id="@+id/ystate"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<SeekBar
 android:id="@+id/zsensitive"   
 android:layout_width="fill_parent"   
 android:layout_height="wrap_content"   
 android:max="100"  
 />  
<TextView
 android:id="@+id/z"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<TextView
 android:id="@+id/zrate"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
<TextView
 android:id="@+id/zstate"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 />
</LinearLayout>

package com.exercise.AndroidDetectShaking;

import java.util.List;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.SeekBar;
import android.widget.TextView;

public class AndroidDetectShaking extends Activity {
 
 TextView text_x, text_xrate, text_xstate;
 TextView text_y, text_yrate, text_ystate;
 TextView text_z, text_zrate, text_zstate;
 SeekBar seekbar_x, seekbar_y, seekbar_z;
 
 SensorManager sensorManager;
    Sensor accelerometerSensor;
    boolean accelerometerPresent;
    
    float SensitiveX, SensitiveY, SensitiveZ;
 
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        seekbar_x = (SeekBar)findViewById(R.id.xsensitive);
        text_x = (TextView)findViewById(R.id.x);
        text_xrate = (TextView)findViewById(R.id.xrate);
        text_xstate = (TextView)findViewById(R.id.xstate);
        seekbar_y = (SeekBar)findViewById(R.id.ysensitive);
        text_y = (TextView)findViewById(R.id.y);
        text_yrate = (TextView)findViewById(R.id.yrate);
        text_ystate = (TextView)findViewById(R.id.ystate);
        seekbar_z = (SeekBar)findViewById(R.id.zsensitive);
        text_z = (TextView)findViewById(R.id.z);
        text_zrate = (TextView)findViewById(R.id.zrate);
        text_zstate = (TextView)findViewById(R.id.zstate);
        
        seekbar_x.setOnSeekBarChangeListener(seekbar_sensitiveOnSeekBarChangeListener);
        seekbar_y.setOnSeekBarChangeListener(seekbar_sensitiveOnSeekBarChangeListener);
        seekbar_z.setOnSeekBarChangeListener(seekbar_sensitiveOnSeekBarChangeListener);
        
        sensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
        List<Sensor> sensorList = sensorManager.getSensorList(Sensor.TYPE_ACCELEROMETER);
        if(sensorList.size() > 0){
         accelerometerPresent = true;
         accelerometerSensor = sensorList.get(0);  
        }
        else{
         accelerometerPresent = false;  
        }
    }
    
    SeekBar.OnSeekBarChangeListener seekbar_sensitiveOnSeekBarChangeListener
    = new SeekBar.OnSeekBarChangeListener(){

  @Override
  public void onProgressChanged(SeekBar arg0, int arg1, boolean arg2) {
   // TODO Auto-generated method stub
   if (arg0 == seekbar_x){
    SensitiveX = (float)arg1;
   }else if (arg0 == seekbar_y){
    SensitiveY = (float)arg1;
   }else if (arg0 == seekbar_z){
    SensitiveZ = (float)arg1;
   }
  }

  @Override
  public void onStartTrackingTouch(SeekBar arg0) {
   // TODO Auto-generated method stub
  }

  @Override
  public void onStopTrackingTouch(SeekBar arg0) {
   // TODO Auto-generated method stub
  }};
    
    @Override
 protected void onResume() {
  // TODO Auto-generated method stub
  super.onResume();
  if(accelerometerPresent){
   sensorManager.registerListener(accelerometerListener, accelerometerSensor, SensorManager.SENSOR_DELAY_NORMAL);  
  }
 }

 @Override
 protected void onStop() {
  // TODO Auto-generated method stub
  super.onStop();
  if(accelerometerPresent){
   sensorManager.unregisterListener(accelerometerListener);  
  }
 }

 private SensorEventListener accelerometerListener = new SensorEventListener(){
  
  float lastx, lasty, lastz;
  long lasttime;
  boolean firsttime = true;

  @Override
  public void onAccuracyChanged(Sensor arg0, int arg1) {
   // TODO Auto-generated method stub
  }

  @Override
  public void onSensorChanged(SensorEvent arg0) {
   // TODO Auto-generated method stub
   float x_value = arg0.values[0];
   float y_value = arg0.values[1];
   float z_value = arg0.values[2];
   text_x.setText(String.valueOf(x_value));
   text_y.setText(String.valueOf(y_value));
   text_z.setText(String.valueOf(z_value));
   
   long currenttime = System.currentTimeMillis();
   if(!firsttime){
    long deltatime = currenttime - lasttime;
    float xrate = Math.abs(x_value - lastx) * 10000/deltatime;
    float yrate = Math.abs(y_value - lasty) * 10000/deltatime;
    float zrate = Math.abs(z_value - lastz) * 10000/deltatime;
    text_xrate.setText(String.valueOf(xrate));
    text_yrate.setText(String.valueOf(yrate));
    text_zrate.setText(String.valueOf(zrate));
    
    if (xrate>SensitiveX){
     text_xstate.setText("Shaking:)");
    }else{
     text_xstate.setText("");
    }
    
    if (yrate>SensitiveY){
     text_ystate.setText("Shaking:)");
    }else{
     text_ystate.setText("");
    }
    
    if (zrate>SensitiveZ){
     text_zstate.setText("Shaking:)");
    }else{
     text_zstate.setText("");
    }
   }
   lasttime = currenttime;
   lastx = x_value;
   lasty = y_value;
   lastz = z_value;
   firsttime = false;
  }
 };
}

Download the files.