Question

所以我试图制作一个跟踪手机指向哪个方向的应用程序VIA指南针，一旦屏幕上出现一个按钮，就会显示指向度数的位置。到目前为止，我理解指南针是如何创建的，但无法找到哪些值是与北方相关的指向方向。这是我到目前为止所做的。

public class compass extends Activity implements OnClickListener, SensorEventListener{

    private final SensorManager DirPoint;
    float var;
    TextView theNumber;

    Button DirectionIn;

    public compass(){ 
        DirPoint = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    }

    public void onAccuracyChanged(Sensor sensor, int accuracy) {}
    public void onSensorChanged(SensorEvent event) {}

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        theNumber = (textView) findViewById(R.id.output);
        DirectionIn =(Button) findViewById(R.Id.Buton);

        DirectionIn.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {
                //gets direction of phone compass
                // ((TextView)findViewById(R.id.output)).setText(var);
            }
        }
    }
}

任何帮助都会受到欢迎，或者如果我朝着正确的方向前进，那就更好了。

Answer 1

你必须实施“指南针”。你可以这样做：

让您的活动实现SensorEventListener并添加必要的字段：

public class CompassActivity extends Activity implements SensorEventListener {

    private SensorManager sensorManager;
    private Sensor accelerometer;
    private Sensor magnetometer;
    private float[] lastAccelerometer = new float[3];
    private float[] lastMagnetometer = new float[3];
    private boolean lastAccelerometerSet = false;
    private boolean lastMagnetometerSet = false;
    private float[] rotationMatrix = new float[9];
    private float[] orientation = new float[3];
    private float currentDegree = 0f;

在活动的onCreate方法中获取并启动两个传感器，加速度计和磁力计：

        // onCreate method stub ...
        sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        accelerometer = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        magnetometer = sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
        sensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_UI);
        sensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_UI);
        // more onCreate method stub ....

在SensorEventListener的方法中，您现在可以计算手机的标题并计算当前位置与其他位置之间的方位：

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor == this.accelerometer) {
            System.arraycopy(event.values, 0, this.lastAccelerometer, 0, event.values.length);
            this.lastAccelerometerSet = true;
        } else if (event.sensor == this.magnetometer) {
            System.arraycopy(event.values, 0, this.lastMagnetometer, 0, event.values.length);
            this.lastMagnetometerSet = true;
        }

        if (this.lastAccelerometerSet && this.lastAccelerometerSet) {
            SensorManager.getRotationMatrix(this.rotationMatrix,null, this.lastAccelerometer, this.lastMagnetometer);
            SensorManager.getOrientation(this.rotationMatrix, this.orientation);


            float azimuthInRadiands = this.orientation[0];

            // this is now the heading of the phone. If you want
            // to rotate a view to north don´t forget that you have
            // to rotate by the negative value.
            float azimuthInDegrees = (float) Math.toDegrees(azimuthInRadiands);

        }
    }

但不要忘记指南针背后还有更多。如果磁场传感器未校准，则必须向用户显示。你必须计算磁场和地理北方之间的差异......

我创建了一个小型罗盘助手类。 HowTo在自述文件中。它将为您提供在屏幕上显示指南针所需的所有信息：

Compass Assistant on GitHub

它为您提供设备的当前标题。如果您有问题，请随时问我。

Answer 2

详情请见here

使用TYPE_ACCELEROMETER和TYPE_MAGNETIC_FIELD的组合。

        Sensor beschleunigung = sensor.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0);
        Sensor magnetometer = sensor.getSensorList(Sensor.TYPE_MAGNETIC_FIELD).get(0);
        sensor.registerListener(handler, beschleunigung, SensorManager.SENSOR_DELAY_NORMAL, null);
        sensor.registerListener(handler, magnetometer, SensorManager.SENSOR_DELAY_NORMAL, null);

和

handler = new SensorEventListener() {
        float[] mGravity;
        float[] mGeomagnetic;

        @Override
        public void onSensorChanged( SensorEvent event ) {
            if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
                mGravity = event.values;
            if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
                mGeomagnetic = event.values;
            if (mGravity != null && mGeomagnetic != null) {
                float R[] = new float[9];
                float I[] = new float[9];
                boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic);
                if (success) {
                    float orientation[] = new float[3];
                    SensorManager.getOrientation(R, orientation);
                    azimut = orientation[0]; // orientation contains: azimut, pitch and roll
                }
            }

            NavigationArrow.this.setOffsetFromNorth((float) Math.toDegrees(azimut));
        }

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

        }
    };

希望有所帮助：）

Android指南针问题

2 个答案: