java - 为什么我无法从加速度计传感器获取数据？

Question

问题描述:

我和我的 friend 正在自学 Android 开发。我们调试了其他类，例如游戏物理和手动更新的值，这使得弹珠沿着我们的棋盘对角线移动。当我们将其改回读取加速度计数据时，大理石停止移动。因此，我们将包括我们认为发生问题的类。基本上就是我们在android开发中的 View 类。

我们正在自学 Android 开发，我们无法理解为什么来自加速度计(我们称之为 mSensorX 和 mSensorY)的数据没有被更新。下面包含的是我们的 View 类。请注意，我们正在针对 android 3.1 进行开发。然而，我们在 Eclipse 中使用了 Android 的所有最新功能。

package com.example.marblez;


import com.example.marblez.R;
import android.app.Activity;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.util.Log;
import android.view.Display;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.Surface;
import android.view.View;
import android.view.WindowManager;

public class MarblezView extends View implements SensorEventListener{


//Sensor Stuff
private SensorManager mSensorManager;
private Display mDisplay;


//Accelerometer sensor stuff 
 private Sensor mAccelerometer;
 private float mSensorX;
 private float mSensorY;

 //Variables related to time 
 private long mCpuTimeStamp;
 private long mSensorTimeStamp;
 private WindowManager mWindowManager;



//Accelerometer buffer, such that slight movement will roll the marble 
private float sensor_buffer = 0;

//Create the canvas 
private Canvas mCanvas; 
private MarblezBackground background;

//Create the marble
private Marblez ball;

//Constructor for Marblez View 
@SuppressWarnings("deprecation")
public MarblezView(Context context, Activity activity){
    super(context);

    //Setup sensor stuff
    mSensorManager = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
    mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
    mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    mDisplay = mWindowManager.getDefaultDisplay();

    //Set up Maze 
    background = new MarblezBackground(activity);

    //Create our rolling little friend :-) 
    ball = new Marblez(activity);

}

 @Override
 public void onSensorChanged(SensorEvent event) {
     if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER)
         return;
     /*
      * record the accelerometer data, the event's timestamp as well as
      * the current time. The latter is needed so we can calculate the
      * "present" time during rendering. In this application, we need to
      * take into account how the screen is rotated with respect to the
      * sensors (which always return data in a coordinate space aligned
      * to with the screen in its native orientation).
      */

     switch (mDisplay.getRotation()) {
         case Surface.ROTATION_0:
             mSensorX = event.values[0];
             mSensorY = event.values[1];
             break;
         case Surface.ROTATION_90:
             mSensorX = -event.values[1];
             mSensorY = event.values[0];
             break;
         case Surface.ROTATION_180:
             mSensorX = -event.values[0];
             mSensorY = -event.values[1];
             break;
         case Surface.ROTATION_270:
             mSensorX = event.values[1];
             mSensorY = -event.values[0];
             break;
     }

     mSensorTimeStamp = event.timestamp;
     mCpuTimeStamp = System.nanoTime();
 }


//Automatic call
@Override
public void onDraw(Canvas canvas){
    mCanvas = canvas;

    //Draw the maze
    background.drawMaze(canvas);

    //Get the x and y sensor data and other goodies
    final long now = mSensorTimeStamp + (System.nanoTime() - mCpuTimeStamp);

    //Draw the marble 
    ball.drawMarble(canvas, mSensorX, mSensorY, now);

    //Invalidate so it draws again 
    invalidate();

}

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

}

我们从一个名为 Accelerometer Play 的开源 Google 项目中获得了很多想法和方法。然而，熟悉该代码的人可以看到我们竭尽全力尝试简化命名约定、方法和调用。

基本上，我们非常感谢您的帮助。就好像传感器“在那里”，但出于实际目的它从未被使用过。例如，很明显，当我们向 View 添加调试标记时， View 从未调用方法 onSensorChanged。因此，另一种情况是我们的加速度计确实不起作用。

Answer 1

您需要在传感器管理器中注册您的实例，如下所示:

mSensorManager.registerListener(this, mAccelerometer,
                                SensorManager.SENSOR_DELAY_NORMAL);