4

无论当前的屏幕方向（横向或纵向）如何，我都想获得当前的磁方向。

我找到了这个例子，但它与方向无关，对吧？这也没有帮助我。我也读过http://android-developers.blogspot.de/2010/09/one-screen-turn-deserves-another.html。

这是我目前不推荐使用的方法，我不想使用（简短）：

mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);

private SensorEventListener sensorEventListener = new SensorEventListener() {

    public void onSensorChanged(SensorEvent event) {

        /* Get measured value */
        float current_measured_bearing = (float) event.values[0];

        /* Compensate device orientation */
        switch (((WindowManager) getSystemService(WINDOW_SERVICE))
                .getDefaultDisplay().getRotation()) {
        case Surface.ROTATION_90:
            current_measured_bearing = current_measured_bearing + 90f;
            break;
        case Surface.ROTATION_180:
            current_measured_bearing = current_measured_bearing - 180f;
            break;
        case Surface.ROTATION_270:
            current_measured_bearing = current_measured_bearing - 90f;
            break;
        }

但最后一部分绝对是错误的！在这种情况下如何正确使用较新的方法getRotationMatrix()？（与方向无关）还是我只需要使用event.values[]基于旋转矩阵的数组的其他值？还是我需要“重新映射坐标”？那么这是实现这一目标的正确方法吗？

我正在为具有 360° 屏幕旋转和 API 级别 11+ 的设备进行开发。

我知道这些问题经常被问到，但我根本无法将他们的答案转移到我的问题上。

4

3 回答 3

8

好的，我终于设法让代码工作了！

首先，我注册一个Sensor.TYPE_MAGNETIC_FIELD和Sensor.TYPE_GRAVITY：（就像 Hoan Nguyen 说的！）

/**
 * Initialize the Sensors (Gravity and magnetic field, required as a compass
 * sensor)
 */
private void initSensors() {

    LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
    SensorManager sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    Sensor mSensorGravity = sensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
    Sensor mSensorMagneticField = sensorManager
            .getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);

    /* Initialize the gravity sensor */
    if (mSensorGravity != null) {
        Log.i(TAG, "Gravity sensor available. (TYPE_GRAVITY)");
        sensorManager.registerListener(mSensorEventListener,
                mSensorGravity, SensorManager.SENSOR_DELAY_GAME);
    } else {
        Log.i(TAG, "Gravity sensor unavailable. (TYPE_GRAVITY)");
    }

    /* Initialize the magnetic field sensor */
    if (mSensorMagneticField != null) {
        Log.i(TAG, "Magnetic field sensor available. (TYPE_MAGNETIC_FIELD)");
        sensorManager.registerListener(mSensorEventListener,
                mSensorMagneticField, SensorManager.SENSOR_DELAY_GAME);
    } else {
        Log.i(TAG,
                "Magnetic field sensor unavailable. (TYPE_MAGNETIC_FIELD)");
    }
}

我用它SensorEventListner来计算：

private SensorEventListener mSensorEventListener = new SensorEventListener() {

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

    @Override
    public void onSensorChanged(SensorEvent event) {

        if (event.sensor.getType() == Sensor.TYPE_GRAVITY) {

            mGravity = event.values.clone();

        } else if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {

            mMagnetic = event.values.clone();

        }

        if (mGravity != null && mMagnetic != null) {

            /* Create rotation Matrix */
            float[] rotationMatrix = new float[9];
            if (SensorManager.getRotationMatrix(rotationMatrix, null,
                    mGravity, mMagnetic)) {

                /* Compensate device orientation */
                // http://android-developers.blogspot.de/2010/09/one-screen-turn-deserves-another.html
                float[] remappedRotationMatrix = new float[9];
                switch (getWindowManager().getDefaultDisplay()
                        .getRotation()) {
                case Surface.ROTATION_0:
                    SensorManager.remapCoordinateSystem(rotationMatrix,
                            SensorManager.AXIS_X, SensorManager.AXIS_Y,
                            remappedRotationMatrix);
                    break;
                case Surface.ROTATION_90:
                    SensorManager.remapCoordinateSystem(rotationMatrix,
                            SensorManager.AXIS_Y,
                            SensorManager.AXIS_MINUS_X,
                            remappedRotationMatrix);
                    break;
                case Surface.ROTATION_180:
                    SensorManager.remapCoordinateSystem(rotationMatrix,
                            SensorManager.AXIS_MINUS_X,
                            SensorManager.AXIS_MINUS_Y,
                            remappedRotationMatrix);
                    break;
                case Surface.ROTATION_270:
                    SensorManager.remapCoordinateSystem(rotationMatrix,
                            SensorManager.AXIS_MINUS_Y,
                            SensorManager.AXIS_X, remappedRotationMatrix);
                    break;
                }

                /* Calculate Orientation */
                float results[] = new float[3];
                SensorManager.getOrientation(remappedRotationMatrix,
                        results);

                /* Get measured value */
                float current_measured_bearing = (float) (results[0] * 180 / Math.PI);
                if (current_measured_bearing < 0) {
                    current_measured_bearing += 360;
                }

                /* Smooth values using a 'Low Pass Filter' */
                current_measured_bearing = current_measured_bearing
                        + SMOOTHING_FACTOR_COMPASS
                        * (current_measured_bearing - compass_last_measured_bearing);

                /* Update normal output */
                visual_compass_value.setText(String.valueOf(Math
                        .round(current_bearing))
                        + getString(R.string.degrees));

                /*
                 * Update variables for next use (Required for Low Pass
                 * Filter)
                 */
                compass_last_measured_bearing = current_measured_bearing;

            }
        }
    }
};
于 2013-08-18T12:57:17.803 回答
4

Sensor.TYPE_ORIENTATION是折旧的，只有在设备平坦的情况下才是好的。使用时Sensor.TYPE_ORIENTATION，方位角（方位角）是设备Y-axis指向的方向。因此，如果设备保持垂直，则Y-axis用作轴承的点的方向没有意义。只有计算后置摄像头指向的方向才有意义。要找到这个方向，您必须使用Sensor.TYPE_MAGNETIC_FIELDandSensor.TYPE_GRAVITY或Sensor.TYPE_ACCELEROMETER。如果使用Sensor.TYPE_ACCELEROMETER，则必须过滤加速度计值。
使用这些传感器，您调用getRotationMatrix然后remapCoordinateSystem(inR, AXIS_X, AXIS_Z, outR)调用之前getOrientation。要获得稳定的方向，您应该保留方向的历史记录，然后计算平均值。对于使用 TYPE_GRAVITY 检查的实现当手机倾斜时，Android getOrientation 方位角会被污染

于 2013-08-11T05:14:51.907 回答
0

我认为这段代码可以帮助你：

    //get orientation
private int getScreenOrientation() {
    int rotation = getWindowManager().getDefaultDisplay().getRotation();
    DisplayMetrics dm = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(dm);
    int width = dm.widthPixels;
    int height = dm.heightPixels;
    int orientation;
    // if the device's natural orientation is portrait:
    if ((rotation == Surface.ROTATION_0
            || rotation == Surface.ROTATION_180) && height > width ||
        (rotation == Surface.ROTATION_90
            || rotation == Surface.ROTATION_270) && width > height) {
        switch(rotation) {
            case Surface.ROTATION_0:
                orientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT;
                break;
            case Surface.ROTATION_90:
                orientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
                break;
            case Surface.ROTATION_180:
                orientation =
                    ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT;
                break;
            case Surface.ROTATION_270:
                orientation =
                    ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE;
                break;
            default:
                Log.e(TAG, "Unknown screen orientation. Defaulting to " +
                        "portrait.");
                orientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT;
                break;              
        }
    }
    // if the device's natural orientation is landscape or if the device
    // is square:
    else {
        switch(rotation) {
            case Surface.ROTATION_0:
                orientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
                break;
            case Surface.ROTATION_90:
                orientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT;
                break;
            case Surface.ROTATION_180:
                orientation =
                    ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE;
                break;
            case Surface.ROTATION_270:
                orientation =
                    ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT;
                break;
            default:
                Log.e(TAG, "Unknown screen orientation. Defaulting to " +
                        "landscape.");
                orientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
                break;              
        }
    }

    return orientation;
}
于 2013-08-11T08:31:43.750 回答