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我已经编写了一个代码来借助 android 中的加速度计移动一个球，这样如果它触及 4 个边缘中的任何一个，它就会重新出现在对面的边缘上，我的问题是

1.ball 没有重新出现在对边 2.orientation 改变为 lanscape

这是我的代码 

 public class Accelerate extends Activity implements SensorEventListener {

float x, y, sensorX, sensorY, a, b, centerX, centerY;
Bitmap ball;
SensorManager sm;
NixSurface ourSurfaceView;

public class NixSurface extends SurfaceView implements Runnable {

    SurfaceHolder ourHolder;
    Thread ourThread = null;
    boolean isRunning = false;

    public NixSurface(Context context) {
        super(context);
        ourHolder = getHolder();

    }

    public void pause() {
        isRunning = false;
        while (true) {
            try {
                ourThread.join();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            break;
        }
        ourThread = null;
    }

    public void resume() {
        isRunning = true;
        ourThread = new Thread(this);
        ourThread.start();
    }

    public void run() {
        // TODO Auto-generated method stub
        while (isRunning) {
            if (!ourHolder.getSurface().isValid())
                continue;

            Canvas canvas = ourHolder.lockCanvas();

            canvas.drawRGB(255, 255, 255);
            centerX = canvas.getWidth() / 2;
            centerY = canvas.getHeight() / 2;
            x += sensorX;
            y += sensorY;
            a = centerX + x;
            b = centerY + y;

            if (a > canvas.getWidth())
                a = 0;
            if (b > canvas.getHeight())
                b = 0;
            if (a < 0)
                a = canvas.getWidth();
            if (b < 0)
                b = canvas.getHeight();

            canvas.drawBitmap(ball, a, b, null);
            ourHolder.unlockCanvasAndPost(canvas);
        }
    }

}

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    sm = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
    if (sm.getSensorList(Sensor.TYPE_ACCELEROMETER).size() != 0) {
        Sensor s = sm.getSensorList(Sensor.TYPE_ACCELEROMETER).get(0);
        sm.registerListener(this, s, SensorManager.SENSOR_DELAY_NORMAL);
    }
    x = y = sensorY = sensorX = 0;
    ball = BitmapFactory.decodeResource(getResources(), R.drawable.nix);
    ourSurfaceView = new NixSurface(this);
    ourSurfaceView.resume();
    setContentView(ourSurfaceView);
}

@Override
protected void onStop() {
    // TODO Auto-generated method stub
    sm.unregisterListener(this);
    super.onStop();
}

public void onAccuracyChanged(Sensor sensor, int accuracy) {
    // TODO Auto-generated method stub
    // nothing to do here
}

public void onSensorChanged(SensorEvent event) {
    // TODO Auto-generated method stub

    try {
        Thread.sleep(16);
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    sensorX = -event.values[0];
    sensorY = event.values[1];
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}

}

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1 回答 1

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我猜您的问题是您假设传感器原点 (x=0,y=0) 是屏幕中心。传感器原点是屏幕的左上角（X 指向左侧，Y 指向下方），因此将 a & b 与canvas.getWidth()&进行比较canvas.getHeight()是不正确的，因为您已经添加了centerX& centerY。此外，否定sensorX将导致条件a > canvas.getWidth()永远不会发生，因为 X 永远不会是负数。

于 2012-07-01T13:13:10.387 回答