Android手势识别-垂直线

我正在创建一个android应用程序。其中我正在识别直线(垂直和水平)。我使用了以下步骤。

1) Creating straight lines gesture file using "Gestures Builder" application. 
2) Added the "gestures" file in my application and used the "OnGesturePerformedListener" to recognize the line.

The problem is,
I can't recognize the vertical lines(Both Top to Bottom & Bottom to Top).

我能认出直线而不是竖线。有人知道如何检测垂直线吗?

代码段:

public class GestureActivity extends Activity implements OnGesturePerformedListener {
    private GestureLibrary mLibrary;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    GestureOverlayView gestureOverlayView = new GestureOverlayView(this);
    View inflate = getLayoutInflater().inflate(R.layout.activity_gesture,
            null);
    gestureOverlayView.addView(inflate);
    gestureOverlayView.addOnGesturePerformedListener(this);
    mLibrary = GestureLibraries.fromRawResource(this, R.raw.gestures);
    if (!mLibrary.load()) {
        finish();
    }
    setContentView(gestureOverlayView);
}

@Override
public void onGesturePerformed(GestureOverlayView overlay, Gesture gesture) {
    ArrayList<Prediction> predictions = mLibrary.recognize(gesture);
    if (predictions.size() > 0) {
        Prediction prediction = predictions.get(0);
        if (prediction.name.equals("Line") && prediction.score > 1.0) {
            Toast.makeText(this, "Line", Toast.LENGTH_LONG).show();
        }
    }

}

}