简单的指南针开发

 1 import android.app.Activity;
 2 import android.content.Context;
 3 import android.graphics.Matrix;
 4 import android.hardware.Sensor;
 5 import android.hardware.SensorEvent;
 6 import android.hardware.SensorEventListener;
 7 import android.hardware.SensorManager;
 8 import android.os.Bundle;
 9 import android.view.animation.Animation;
10 import android.view.animation.RotateAnimation;
11 import android.widget.ImageView;
12 
13 public class MainActivity extends Activity {
14     private ImageView imageView;
15     private SensorManager manager;
16     private SensorListener listener = new SensorListener();
17     @Override
18     public void onCreate(Bundle savedInstanceState) {
19         super.onCreate(savedInstanceState);
20         setContentView(R.layout.main);
21         
22         imageView = (ImageView) this.findViewById(R.id.imageView);
23         imageView.setKeepScreenOn(true);
24         manager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
25     }
26 
27 
28     @Override
29     protected void onResume() {
30         
31     
32         Sensor sensor = manager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
33         manager.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_GAME);
34         super.onResume();
35     }
36 
37     @Override
38     protected void onPause() {
39         manager.unregisterListener(listener);
40         super.onPause();
41     }
42     
43 
44     
45     private final class SensorListener implements SensorEventListener{
46         private float predegree = 0;
47         public void onSensorChanged(SensorEvent event) {
48             float degree = event.values[0];//存放了方向值 90
49             RotateAnimation animation = new RotateAnimation(predegree, -degree, 
50                     Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
51 
52             animation.setDuration(200);
53             imageView.startAnimation(animation);
54             predegree = -degree;
55         }
56 
57         public void onAccuracyChanged(Sensor sensor, int accuracy) {
58         }
59     }
60     
61     
62 }