问题描述
我建立一个Android应用程序,它会记录度的设备的罗盘到文件中。有两种方法得到这个度:
I am building an Android application which logs the degrees of the compass of the device into a file. There are two methods the get this degrees:
方法1:
SensorManager mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
Sensor orientationSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
mSensorManager.registerListener(this, orientationSensor, SensorManager.SENSOR_DELAY_NORMAL);
public void onSensorChanged(SensorEvent event) {
float azimuthInDegrees = event.values[0]
}
方法2:
SensorManager mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
Sensor accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
Sensor magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);
mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_NORMAL);
float[] mGravity;
float[] mGeomagnetic;
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);
float azimuthInDegress = ((float) Math.toDegrees(orientation[0]) + 360) % 360;
}
}
}
我放置我的设备在北方方向(即360度)尝试了两种方法
方法1 返回完美的效果但遗憾的是这种方法去precated:
Method 1 returns perfect results but unfortunately this method is deprecated:
- 359.6567
- 359.5034
- 359.859
- 359.76212
- 359.8878
- 359.87048
- 359.8356
- 359.80356
- 359.81192
- 359.7671
- 359.84668
- 359.88528
方法2 也返回了良好的效果,但有时(随机),它会返回一个不正确度:
Method 2 also returns good results but sometimes (randomly) it returns an incorrect degree:
- 359.91495
- 359.83652
- 263.67697
- 359.67993
- 359.70038
- 359.688
- 359.71155
- 359.70276
- 359.6984
- 359.6429
- 270.6323
- 359.62302
- 359.49954
- 359.44757
- 359.47803
- 359.4947
- 359.39572
正如你所看到的,一些不正确的度是随机的第二种方法返回。该设备校准,我认为这个问题是第二个方法,第一个方法返回完美的效果。你们能帮助我吗?
As you can see, some incorrect degrees are randomly returned with the second method. The device is calibrated and I think that the problem is with the second method as the first method returns perfect results. Can you guys help me out?
推荐答案
这个问题在的assigment mGravity
和 mGeomagnetic
应该是 event.values.clone()
。 mGravity有一流的范围,但通过使用mGravity = event.values,你有方法范围的地址赋给它的值的值。所以一旦onSensorChanged被再次调用,它是磁类型,mGravity现在指向不再存在,因此可以具有任何值的变量。
The problem is in the assigment of mGravity
and mGeomagnetic
it should be event.values.clone()
. mGravity has class scope but, by using mGravity = event.values, you assign its value to a value in an address that has method scope. So as soon as onSensorChanged is called again and it is magnetic type, the mGravity is now pointing to a variable which no longer exists and thus can have any value.
这篇关于Android的磁力返回随机值的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!