rotation太抖了

[negier]

我在你的MoltiTouchGestureDetector中的getRotation打了Log，结果看到抖得呀。`

public float getRotation() {
    Log.e("TAXXG", "mCurrentRotation：" + mCurrentRotation+"，mPreviousRotation：" + mPreviousRotation);
    return mCurrentRotation - mPreviousRotation;
  }

这是log：

2020-01-20 16:05:05.143 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：39.256565，mPreviousRotation：79.86514
2020-01-20 16:05:05.143 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：39.256565，mPreviousRotation：79.86514
2020-01-20 16:05:05.159 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：79.28215，mPreviousRotation：39.256565
2020-01-20 16:05:05.159 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：79.28215，mPreviousRotation：39.256565
2020-01-20 16:05:05.175 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：38.722054，mPreviousRotation：79.28215
2020-01-20 16:05:05.175 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：38.722054，mPreviousRotation：79.28215
2020-01-20 16:05:05.192 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：78.073975，mPreviousRotation：38.722054
2020-01-20 16:05:05.192 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：78.073975，mPreviousRotation：38.722054
2020-01-20 16:05:05.204 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：38.446537，mPreviousRotation：78.073975
2020-01-20 16:05:05.205 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：38.446537，mPreviousRotation：78.073975
2020-01-20 16:05:05.204 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：38.446537，mPreviousRotation：78.073975
2020-01-20 16:05:05.205 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：38.446537，mPreviousRotation：78.073975
2020-01-20 16:05:05.207 17244-17244/com.dinuscxj.gesturedetector.demo E/TAXXG: mCurrentRotation：0.0，mPreviousRotation：0.0

可以看到其每隔两次，他们的值就互换了，在代码中就是旋转角度在一会儿正，一会儿负，View就很抖。这是我往右转一气呵成的，还是这样。