我有一个扩展SimpleOnPageChangeListener类，并在我的onPageScrollStateChanged方法，我希望能够确定用户是否刷卡向前或向后通过ViewPager。即他们是否有刷卡从左或从右到左。

I have a class that extends SimpleOnPageChangeListener and in my onPageScrollStateChanged method I want to be able to determine whether the user has swiped forwards or backwards through the ViewPager. I.e. Whether they have swiped left-to-right or right-to-left.

我已经做了很多谷歌上搜索这个，但我无法找到任何关于它。我期待onPageScrollStateChanged方法将提供一个参数，说明哪个方向轻扫是，但事实并非如此。

I've done a lot of googling on this but I can't find anything about it. I was expecting the onPageScrollStateChanged method would provide a parameter stating which direction the swipe was but it doesn't.

    @Override
    public void onPageScrollStateChanged(int state) {

        // Determine whether the user is swiping forwards or backwards through the ViewPager
    }

有没有人有什么想法？

Does anyone have any ideas?

干杯 迈克

推荐答案

使用的ViewPager.SimpleOnPageChangeListener，并保持一个实例变种与当前选项卡POS机，这样就可以计算出哪一种方式它被偷走。

Use the ViewPager.SimpleOnPageChangeListener and keep a instance var with the current tab pos, that way you can work out which way it's been swiped.

private final ViewPager.SimpleOnPageChangeListener mPageChangeListener = new ViewPager.SimpleOnPageChangeListener() {

        @Override
        public void onPageSelected(final int position) {
            onTabChanged(mPager.getAdapter(), mCurrentTabPosition, position);
            mCurrentTabPosition = position;
        }
    };

 protected void onTabChanged(final PagerAdapter adapter, final int oldPosition, final int newPosition) {
        //Calc if swipe was left to right, or right to left
         if (oldPosition>newPosition){
           // left to right
         }
         else{
           //right to left 
         }

    }