java - onFling 仅在向左滑动时调用

Question

你好 stackoverflow 社区，

我的 SimpleOnGestureListener 有一个非常奇怪的问题：

public class OnSwipeTouchListener implements View.OnTouchListener {
//constructor...
@SuppressWarnings("deprecation")
private final GestureDetector gestureDetector = new GestureDetector(new GestureListener());

public boolean onTouch(final View v, final MotionEvent event) {
    return gestureDetector.onTouchEvent(event);
}

private final class GestureListener extends GestureDetector.SimpleOnGestureListener {

    private static final int SWIPE_THRESHOLD = 100;
    private static final int SWIPE_VELOCITY_THRESHOLD = 100;    

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        try {
             float diffX = e2.getRawX() - e1.getRawX();
             if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                    if (diffX > 0) {
                        onSwipeRight();
                    }
                    if(diffX < 0) {
                        onSwipeLeft();
                    }
                }
        } catch (Exception exception) {
            exception.printStackTrace();
        }
        return false;
    }
}

public void onSwipeRight() {
    Log.i("PPTREMOTE", "Swiped Right!");
    main.previousSlide();
}

public void onSwipeLeft() {
    Log.i("PPTREMOTE", "Swiped Left!");
    main.nextSlide();
  }
}

我的问题很奇怪。仅当我向左滑动时才调用 onFling ？！

蜉蝣