Android 简易指南针

通过Android的Sensor和动画效果，我们可以制作一个简单的指南针，不过测试和安装的手机必须要支持方向传感器。

布局xml如下：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/ivCompass"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:src="@drawable/image_g" />
</RelativeLayout>

Activity代码：

 

import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity implements SensorEventListener {

    private SensorManager sensorManager;
    private Sensor sensor;
    private ImageView ivCompass;
    private float currentDegree = 0f;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
        ivCompass = (ImageView) findViewById(R.id.ivCompass);

    }

    @Override
    protected void onResume() {
        super.onResume();

        sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);

        /*查看手机所有传感器类型
        List<Sensor> sensorList = sensorManager.getSensorList(Sensor.TYPE_ALL);

        for (Sensor s : sensorList){
            System.out.println(s.getName());
        }
        */
        sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    protected void onPause() {
        super.onPause();
        sensorManager.unregisterListener(this);
    }

    @Override
    public void onSensorChanged(SensorEvent event) {

        switch (event.sensor.getType()) {
            case Sensor.TYPE_ORIENTATION:
                float degree = event.values[0];

                RotateAnimation ra = new RotateAnimation(currentDegree, -degree, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);
                ra.setDuration(200);
                ivCompass.startAnimation(ra);

                //动画停在后来的位置
                ra.setFillAfter(true);

                currentDegree = -degree;
                break;
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {

    }
}