我有一个使用ViewPager和FragmentStatePagerAdapter Android应用程序。不过，我需要添加一个新功能中，我必须知道刷卡方向从一个片段视图移动到另一个，左或右。 （即，我刷卡离开的时候，我会做一件事，当我向右滑动，我会做别的事情）。

I have an Android app that uses ViewPager and FragmentStatePagerAdapter. I however need to add a new feature in which I have to know the swipe direction to move from one fragment view to another, left or right. (i.e, when I swipe left, I would do one thing, and when I swipe right I would do something else).

请注意，我不需要这些事件发生后的刷卡就结束了。我为刷卡时做的那些事件。我想用 setOnPageChangeListener（），但它并没有告诉我刷卡方向。你可以告诉我，请就如何找出刷卡方向？

Please note, I do not need the events to happen AFTER the swipe is over. I have to do those events as the swipe occurs. I thought of using setOnPageChangeListener() but it does not tell me swipe direction. Can you advise me please on how to figure out swipe direction?

感谢。

推荐答案

也许你可以建立一个监听器是这样的：

Maybe you can build a listener like this:

buttonIcons.setOnTouchListener(new OnTouchListener() {

        @Override
        public boolean onTouch(final View v, final MotionEvent event) {
            switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                downX = event.getX();

                return true;

            case MotionEvent.ACTION_UP:

                upX = event.getX();
                final float deltaX = downX - upX;

                if (deltaX > 0 && deltaX > SWIPE_MIN_DISTANCE) {

                    final Animation loadInAnimation = AnimationUtils
                            .loadAnimation(
                                    activity.this,
                                    R.anim.slide_in_right);
                    final Animation loadOutAnimation = AnimationUtils
                            .loadAnimation(
                                    activity.this,
                                    R.anim.slide_out_left);

                    viewFlipper.setInAnimation(loadInAnimation);
                    viewFlipper.setOutAnimation(loadOutAnimation);
                    viewFlipper.showPrevious();

                    startSaveButtonAnimation();

                }
                if (deltaX < 0 && -deltaX > SWIPE_MIN_DISTANCE) {

                    final Animation loadInAnimation = AnimationUtils
                            .loadAnimation(
                                    activity.this,
                                    R.anim.slide_in_left);
                    final Animation loadOutAnimation = AnimationUtils
                            .loadAnimation(
                                    activity.this,
                                    R.anim.slide_out_right);

                    viewFlipper.setInAnimation(loadInAnimation);
                    viewFlipper.setOutAnimation(loadOutAnimation);
                    viewFlipper.showNext();

                    startSaveButtonAnimation();

                }
                return true;

            }

            return false;
        }
    });