Android Compass Code Example

By: Unknown 0 comments

Today I’m going to share a working code to make a very simple compass application for your android device.
 
Some android device (like Huawei Y300 and Lenovo P700i) does not have full support of motions sensors so this code will not work for them.

Files Needed

You need to create your own compass image. For this example, I’m using a stock photo. Your image must be a PNG with transparent background, do not use this jpg file I used.

Add caption

Let’s Code

Here’s our MainActivity.java

01	package com.example.compassapp;

02

03	import android.app.Activity;

04	import android.hardware.Sensor;

05	import android.hardware.SensorEvent;

06	import android.hardware.SensorEventListener;

07	import android.hardware.SensorManager;

08	import android.os.Bundle;

09	import android.view.animation.Animation;

10	import android.view.animation.RotateAnimation;

11	import android.widget.ImageView;

12	import android.widget.TextView;

13

14	public class MainActivity extends Activity implements SensorEventListener {

15

16	// define the display assembly compass picture

17	private ImageView image;

18

19	// record the compass picture angle turned

20	private float currentDegree = 0f;

21

22	// device sensor manager

23	private SensorManager mSensorManager;

24

25	TextView tvHeading;

26

27

@Override

28	protected void onCreate(Bundle savedInstanceState) {

29	super.onCreate(savedInstanceState);

30	setContentView(R.layout.activity_main);

31

32

//

33	image = (ImageView) findViewById(R.id.main_iv);

34

35	// TextView that will tell the user what degree is he heading

36	tvHeading = (TextView) findViewById(R.id.tvHeading);

37

38	// initialize your android device sensor capabilities

39	mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

40

}

41

42

@Override

43	protected void onResume() {

44	super.onResume();

45

46	// for the system's orientation sensor registered listeners

47	mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),

48	SensorManager.SENSOR_DELAY_GAME);

49

}

50

51

@Override

52	protected void onPause() {

53	super.onPause();

54

55	// to stop the listener and save battery

56	mSensorManager.unregisterListener(this);

57

}

58

59

@Override

60	public void onSensorChanged(SensorEvent event) {

61

62	// get the angle around the z-axis rotated

63	float degree = Math.round(event.values[0]);

64

65	tvHeading.setText("Heading: " + Float.toString(degree) + " degrees");

66

67	// create a rotation animation (reverse turn degree degrees)

68	RotateAnimation ra = new RotateAnimation(

69	currentDegree,

70

-degree,

71	Animation.RELATIVE_TO_SELF, 0.5f,

72	Animation.RELATIVE_TO_SELF,

73

0.5f);

74

75	// how long the animation will take place

76	ra.setDuration(210);

77

78	// set the animation after the end of the reservation status

79	ra.setFillAfter(true);

80

81	// Start the animation

82	image.startAnimation(ra);

83	currentDegree = -degree;

84

85

}

86

87

@Override

88	public void onAccuracyChanged(Sensor sensor, int accuracy) {

89	// not in use

90

}

91

}

Our layout file activity_main.xml

01	<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

02	android:layout_width="match_parent"

03	android:layout_height="match_parent"

04	android:background="#fff" >

05

06

<TextView

07	android:id="@+id/tvHeading"

08	android:layout_width="wrap_content"

09	android:layout_height="wrap_content"

10	android:layout_centerHorizontal="true"

11	android:layout_marginBottom="40dp"

12	android:layout_marginTop="20dp"

13	android:text="Heading: 0.0" />

14

15	<ImageView

16	android:id="@+id/imageViewCompass"

17	android:layout_width="wrap_content"

18	android:layout_height="wrap_content"

19	android:layout_below="@+id/tvHeading"

20	android:layout_centerHorizontal="true"

21	android:src="@drawable/img_compass" />

22

23	</RelativeLayout>

Source Code Download

You can download this sample project here: CompassApp.zip

Some notes

My app orientation is locked to portrait mode. There are no special permissions in the Manifest file.