Android游戏开发之小球重力感应实现（二十五）

    private SensorManager sensorMgr;    
    Sensor sensor = sensorMgr.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);     
      
     //保存上一次 x y z 的坐标  
     float bx = 0;  
     float by = 0;  
     float bz = 0;  
     long btime = 0;//这一次的时间   
     sensorMgr = (SensorManager) getSystemService(SENSOR_SERVICE);     
        SensorEventListener lsn = new SensorEventListener() {     
            public void onSensorChanged(SensorEvent e) {     
               float x = e.values[SensorManager.DATA_X];        
               float y = e.values[SensorManager.DATA_Y];        
               float z = e.values[SensorManager.DATA_Z];    
               //在这里我们可以计算出 X Y Z的数值 下面我们就可以根据这个数值来计算摇晃的速度了   
               //我想大家应该都知道计算速度的公事 速度 = 路程/时间  
               //X轴的速度  
               float speadX = (x - bx) / (System.currentTimeMillis() - btime);   
               //y轴的速度  
               float speadY = (y - by) / (System.currentTimeMillis() - btime);   
               //z轴的速度  
               float speadZ = (z - bz) / (System.currentTimeMillis() - btime);   
               //这样简单的速度就可以计算出来 如果你想计算加速度 也可以 在运动学里，加速度a与速度，  
               //位移都有关系：Vt=V0+at，S=V0*t+1/2at^2， S=（Vt^2-V0^2）/(2a),根据这些信息也可以求解a。   
               //这里就不详细介绍了 公事 应该初中物理课老师就教了呵呵~~  
      
               bx = x;  
               by = y;  
               bz = z;  
      
               btime = System.currentTimeMillis();  
      
      
            }     
                 
            public void onAccuracyChanged(Sensor s, int accuracy) {     
            }     
        };     
        // 注册listener，第三个参数是检测的精确度  
        sensorMgr.registerListener(lsn, sensor, SensorManager.SENSOR_DELAY_GAME);  

真机上的效果图

import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;
import android.view.SurfaceHolder.Callback;


public class SurfaceViewAcitvity extends Activity {

    MyView mAnimView = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);
	// 全屏显示窗口
	requestWindowFeature(Window.FEATURE_NO_TITLE);
	getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
		WindowManager.LayoutParams.FLAG_FULLSCREEN);
	//强制横屏 
	setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
	
	// 显示自定义的游戏View
	mAnimView = new MyView(this);
	setContentView(mAnimView);
    }

    public class MyView extends SurfaceView implements Callback,Runnable ,SensorEventListener{

	 /**每50帧刷新一次屏幕**/  
	public static final int TIME_IN_FRAME = 50; 

	/** 游戏画笔 **/
	Paint mPaint = null;
	Paint mTextPaint = null;
	SurfaceHolder mSurfaceHolder = null;

	/** 控制游戏更新循环 **/
	boolean mRunning = false;

	/** 游戏画布 **/
	Canvas mCanvas = null;

	/**控制游戏循环**/
	boolean mIsRunning = false;
	
	/**SensorManager管理器**/
	private SensorManager mSensorMgr = null;    
	Sensor mSensor = null;    
	
	/**手机屏幕宽高**/
	int mScreenWidth = 0;
	int mScreenHeight = 0;
	
	/**小球资源文件越界区域**/
	private int mScreenBallWidth = 0;
	private int mScreenBallHeight = 0;
	
	/**游戏背景文件**/
	private Bitmap mbitmapBg;
	
	/**小球资源文件**/
	private Bitmap mbitmapBall;
	
	/**小球的坐标位置**/
	private float mPosX = 200;
	private float mPosY = 0;
	
	/**重力感应X轴 Y轴 Z轴的重力值**/
	private float mGX = 0;
	private float mGY = 0;
	private float mGZ = 0;
	
	public MyView(Context context) {
	    super(context);
	    /** 设置当前View拥有控制焦点 **/
	    this.setFocusable(true);
	    /** 设置当前View拥有触摸事件 **/
	    this.setFocusableInTouchMode(true);
	    /** 拿到SurfaceHolder对象 **/
	    mSurfaceHolder = this.getHolder();
	    /** 将mSurfaceHolder添加到Callback回调函数中 **/
	    mSurfaceHolder.addCallback(this);
	    /** 创建画布 **/
	    mCanvas = new Canvas();
	    /** 创建曲线画笔 **/
	    mPaint = new Paint();
	    mPaint.setColor(Color.WHITE);
	    /**加载小球资源**/
	    mbitmapBall = BitmapFactory.decodeResource(this.getResources(), R.drawable.ball);
	    /**加载游戏背景**/
	    mbitmapBg = BitmapFactory.decodeResource(this.getResources(), R.drawable.bg);
	    
	    /**得到SensorManager对象**/
	    mSensorMgr = (SensorManager) getSystemService(SENSOR_SERVICE);   
	    mSensor = mSensorMgr.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);   
	    // 注册listener，第三个参数是检测的精确度  
            //SENSOR_DELAY_FASTEST 最灵敏 因为太快了没必要使用
            //SENSOR_DELAY_GAME    游戏开发中使用
            //SENSOR_DELAY_NORMAL  正常速度
            //SENSOR_DELAY_UI 	       最慢的速度
	    mSensorMgr.registerListener(this, mSensor, SensorManager.SENSOR_DELAY_GAME);  
	}
        
	private void Draw() {
	   
	    /**绘制游戏背景**/
	    mCanvas.drawBitmap(mbitmapBg,0,0, mPaint);
	    /**绘制小球**/
	    mCanvas.drawBitmap(mbitmapBall, mPosX,mPosY, mPaint);
	    /**X轴 Y轴 Z轴的重力值**/
	    mCanvas.drawText("X轴重力值 ：" + mGX, 0, 20, mPaint);
	    mCanvas.drawText("Y轴重力值 ：" + mGY, 0, 40, mPaint);
	    mCanvas.drawText("Z轴重力值 ：" + mGZ, 0, 60, mPaint);
	}
	
	@Override
	public void surfaceChanged(SurfaceHolder holder, int format, int width,
		int height) {

	}

	@Override
	public void surfaceCreated(SurfaceHolder holder) {
	    /**开始游戏主循环线程**/
	    mIsRunning = true;
	    new Thread(this).start();
	    /**得到当前屏幕宽高**/
	    mScreenWidth = this.getWidth();
	    mScreenHeight = this.getHeight();
	    
	    /**得到小球越界区域**/
	    mScreenBallWidth = mScreenWidth - mbitmapBall.getWidth();
	    mScreenBallHeight = mScreenHeight - mbitmapBall.getHeight();
	}

	@Override
	public void surfaceDestroyed(SurfaceHolder holder) {
	    mIsRunning = false;
	}

	@Override
	public void run() {
	    while (mIsRunning) {

		/** 取得更新游戏之前的时间 **/
		long startTime = System.currentTimeMillis();

		/** 在这里加上线程安全锁 **/
		synchronized (mSurfaceHolder) {
		    /** 拿到当前画布 然后锁定 **/
		    mCanvas = mSurfaceHolder.lockCanvas();
		    Draw();
		    /** 绘制结束后解锁显示在屏幕上 **/
		    mSurfaceHolder.unlockCanvasAndPost(mCanvas);
		}

		/** 取得更新游戏结束的时间 **/
		long endTime = System.currentTimeMillis();

		/** 计算出游戏一次更新的毫秒数 **/
		int diffTime = (int) (endTime - startTime);

		/** 确保每次更新时间为50帧 **/
		while (diffTime <= TIME_IN_FRAME) {
		    diffTime = (int) (System.currentTimeMillis() - startTime);
		    /** 线程等待 **/
		    Thread.yield();
		}

	    }

	}
	 
	@Override
	public void onAccuracyChanged(Sensor arg0, int arg1) {
	    // TODO Auto-generated method stub
	    
	}

	@Override
	public void onSensorChanged(SensorEvent event) {
	    mGX = event.values[SensorManager.DATA_X];
	    mGY= event.values[SensorManager.DATA_Y];
	    mGZ = event.values[SensorManager.DATA_Z];

	    //这里乘以2是为了让小球移动的更快
	    mPosX -= mGX * 2;
	    mPosY += mGY * 2;

	    //检测小球是否超出边界
	    if (mPosX < 0) {
		mPosX = 0;
	    } else if (mPosX > mScreenBallWidth) {
		mPosX = mScreenBallWidth;
	    }
	    if (mPosY < 0) {
		mPosY = 0;
	    } else if (mPosY > mScreenBallHeight) {
		mPosY = mScreenBallHeight;
	    }
	}
    }
}