如何计算 ViewPager2 中发生的滑动

Posted 2023-04-18

【中文标题】如何计算 ViewPager2 中发生的滑动

【英文标题】：How to tally the swipes that occur in ViewPager2

【发布时间】：2021-10-12 04:10:05

【问题描述】：

所以我创建了一个带有图片的轮播类型应用程序。我想记录用户的滑动次数并将其显示在计数器上。

*计数器在“滑动次数”旁边

这是我目前在代码中得到的内容

class MainFragment: Fragment() 

//    private lateinit var manager: RecyclerView.LayoutManager
    private lateinit var viewPager: ViewPager2
    private var counter: Int = 0


    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? 
        val binding: MainFragmentBinding = DataBindingUtil.inflate(
            inflater,
            R.layout.main_fragment,
            container, false)

        viewPager = binding.imageSlider


        val data: MutableList<CarouselItem> = ArrayList()
        data.add(CarouselItem(1, bcw_65, "First"))
        data.add(CarouselItem(2, bcw_66, "Second"))
        data.add(CarouselItem(3, bcw_67, "Third"))
        data.add(CarouselItem(4, bcw_68, "Fourth"))
        data.add(CarouselItem(5, bcw_69, "Fifth"))
        data.add(CarouselItem(6, bcw_70, "Sixth"))
        data.add(CarouselItem(2, bcw_71, "Seventh"))

        viewPager.adapter = CarouselItemAdapter(data, viewPager)

        viewPager.clipToPadding = false
        viewPager.clipChildren = false
        viewPager.offscreenPageLimit = 3
        viewPager.getChildAt(0).overScrollMode = RecyclerView.OVER_SCROLL_NEVER

        val compositePageTransformer = CompositePageTransformer()
        compositePageTransformer.addTransformer(MarginPageTransformer(30))
        compositePageTransformer.addTransformer  page, position ->
            val r = 1 - abs(position)
            page.scaleY = 0.85f + r * 0.25f
        

        viewPager.setPageTransformer(compositePageTransformer)

//        binding.imageSlider.setOnTouchListener
        binding.imageSlider.setOnTouchListener  v, event ->
            counter++
            Log.d(TAG, "onCreateView: Swipe Recorded")
            true
        

        binding.counterView.text = counter.toString()




        return binding.root
    

我已经尝试了一些东西，但它似乎仍然没有真正起作用。任何想法将不胜感激。

【问题讨论】：

这能回答你的问题吗？ How to detect the swipe left or Right in android?

“我已经尝试了一些事情” - 你尝试了哪些事情？ OnPageChangedListener 是您尝试过的一件事吗？ developer.android.com/reference/androidx/viewpager/widget/…

我还没有尝试过 OnPageChangedListener。你介意详细说明一下吗？

【参考方案1】：

将ViewPager2.OnPageChangeCallback 添加到您的寻呼机：

class MainFragment: Fragment() 
    private lateinit var viewPager: ViewPager2
    private var counter: Int = 0
    private var pageChangeCallback: ViewPager2.OnPageChangeCallback? = null

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? 
        ...
        viewPager.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() 
            override fun onPageSelected(position: Int) 
                counter++
                binding.counterView.text = counter.toString()
            
        .also  pageChangeCallback = it )
        ...
    

    override fun onDestroyView() 
        super.onDestroyView()
        viewPager.unregisterOnPageChangeCallback(pageChangeCallback!!)
        pageChangeCallback = null
    

【讨论】：

你是绝对正确的。我不完全确定如何实际实现 OnPageChangeCallback。我很感激。