Detecting tilt device by using Sensor in Android

    In this sample application we will put the android accelerometer sensor into use . Nowadays accelerometer is used more in motion games where the user tilts the phone for a specific action to take place or used for shake detection.
    Project description: I will change image drawable in the ImageView and update TextView when user tilt device.
First, set layout for our Activity:

activity_sensor.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/rl"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <TextView
        android:id="@+id/txt"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/img"
        android:gravity="center"
        android:layout_marginTop="10dp"
        android:textColor="@android:color/holo_green_dark"
        android:textSize="20sp" />

    <ImageView
        android:id="@+id/img"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:contentDescription="@string/action_settings"
        android:src="@drawable/center" />

</RelativeLayout>

In programmatically code, have now come to the point, that we should get the accelerometer events, and use them. We are going to get the x,y events, by using the event.values[0], event.values[1] accordingly. When we tilt device, these variables value will be changed, and processing this action in onSensorChanged() method:

 @Override
 public void onSensorChanged(SensorEvent event) {
  float x = event.values[0];
  float y = event.values[1];
  if (Math.abs(x) > Math.abs(y)) {
   if (x < 0) {
    image.setImageResource(R.drawable.right);
    textView.setText("You tilt the device right");
   }
   if (x > 0) {
    image.setImageResource(R.drawable.left);
    textView.setText("You tilt the device left");
   }
  } else {
   if (y < 0) {
    image.setImageResource(R.drawable.up);
    textView.setText("You tilt the device up");
   }
   if (y > 0) {
    image.setImageResource(R.drawable.down);
    textView.setText("You tilt the device down");
   }
  }
  if (x > (-2) && x < (2) && y > (-2) && y < (2)) {
   image.setImageResource(R.drawable.center);
   textView.setText("Not tilt device");
  }
 }

Generally, we do not want these kind of listeners to run to our device continually, because most of the times they appear to be energy and cpu consuming, so we are going to unregister our listener in onPause() of our Activity, and then register them back in onResume(). So, we have to add this code:

 @Override
 protected void onResume() {
  super.onResume();
  sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL);
 }

 @Override
 protected void onPause() {
  super.onPause();
  //unregister Sensor listener 
  sensorManager.unregisterListener(this);
 }

And full SensorActivity.java code:

SensorActivity.java

package com.blogspot.hongthaiit.sensor;

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.os.Bundle;
import android.widget.ImageView;
import android.widget.TextView;

public class SensorActivity extends Activity implements SensorEventListener {

 private SensorManager sensorManager;
 private Sensor sensor;
 private TextView textView;
 private ImageView image;

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_sensor);
  
  //declaring Sensor Manager and sensor type
  sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
  sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
  
  //locate views
  textView = (TextView) findViewById(R.id.txt);
  image = (ImageView) findViewById(R.id.img);
 }

 @Override
 public void onAccuracyChanged(Sensor arg0, int arg1) {
 }

 @Override
 public void onSensorChanged(SensorEvent event) {
  float x = event.values[0];
  float y = event.values[1];
  if (Math.abs(x) > Math.abs(y)) {
   if (x < 0) {
    image.setImageResource(R.drawable.right);
    textView.setText("You tilt the device right");
   }
   if (x > 0) {
    image.setImageResource(R.drawable.left);
    textView.setText("You tilt the device left");
   }
  } else {
   if (y < 0) {
    image.setImageResource(R.drawable.up);
    textView.setText("You tilt the device up");
   }
   if (y > 0) {
    image.setImageResource(R.drawable.down);
    textView.setText("You tilt the device down");
   }
  }
  if (x > (-2) && x < (2) && y > (-2) && y < (2)) {
   image.setImageResource(R.drawable.center);
   textView.setText("Not tilt device");
  }
 }

 @Override
 protected void onResume() {
  super.onResume();
  sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL);
 }

 @Override
 protected void onPause() {
  super.onPause();
  //unregister Sensor listener 
  sensorManager.unregisterListener(this);
 }
}

Some application screenshots (click for full size):

(sorry for ads at download link) 

Author : Hong Thai

Share