The use of gyroscope in Android

The gyroscope, as its name implies, is an instrument for measuring balance. Its measurement result is the inclination angle between the current position and the last position. This angle describes the angle in the three-dimensional space, so its value is determined by the three coordinate axes x, y, and z. The angular offset on the composition. Because the gyroscope has the function of measuring three-dimensional angles, it is also called an angular velocity sensor. The gyroscope can detect the size of the rotation angle, so the use of the gyroscope can restore the rotation behavior of three-dimensional objects.

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/tv_light"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:text=""
        android:textColor="@color/black"
        android:textSize="17sp" />
</LinearLayout>

MainActivity.java

public class MainActivity extends BaseActivity
        implements SensorEventListener {

    private TextView tv_light;
    private SensorManager mSensorMgr;// 声明一个传感管理器对象
    private float mTimestamp; // 记录上次的时间戳
    private float mAngle[] = new float[3]; // 记录xyz三个方向上的旋转角度
    private static final float NS2S = 1.0f / 1000000000.0f; // 将纳秒转化为秒

    @Override
    protected MvcBaseModel getModelImp() {
        return null;
    }

    @Override
    protected int getContentLayoutId() {
        return R.layout.activity_main;
    }

    @Override
    protected void initWidget() {
        tv_light = findViewById(R.id.tv_light);
        // 从系统服务中获取传感管理器对象
        mSensorMgr = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    }

    @Override
    protected void onPause() {
        super.onPause();
        // 注销当前活动的传感监听器
        mSensorMgr.unregisterListener(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        //注册感光器
        mSensorMgr.registerListener(this,
                mSensorMgr.getDefaultSensor(Sensor.TYPE_GYROSCOPE),
                SensorManager.SENSOR_DELAY_NORMAL);
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() == Sensor.TYPE_GYROSCOPE) { // 陀螺仪角度变更事件
            if (mTimestamp != 0) {
                final float dT = (event.timestamp - mTimestamp) * NS2S;
                mAngle[0] += event.values[0] * dT;
                mAngle[1] += event.values[1] * dT;
                mAngle[2] += event.values[2] * dT;
                // x轴的旋转角度，手机平放桌上，然后绕侧边转动
                float angleX = (float) Math.toDegrees(mAngle[0]);
                // y轴的旋转角度，手机平放桌上，然后绕底边转动
                float angleY = (float) Math.toDegrees(mAngle[1]);
                // z轴的旋转角度，手机平放桌上，然后水平旋转
                float angleZ = (float) Math.toDegrees(mAngle[2]);
                String desc = String.format("陀螺仪检测到当前\nx轴方向的转动角度为%f\ny轴方向的转动角度为%f\nz轴方向的转动角度为%f",
                        angleX, angleY, angleZ);
                tv_light.setText(desc);
            }
            mTimestamp = event.timestamp;
        }
    }

    //当传感器精度改变时回调该方法，一般无需处理
    public void onAccuracyChanged(Sensor sensor, int accuracy) {}
}

In this way, we know which axis the mobile phone is rotating around.

The use of gyroscope in Android

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