RecyclerView Realizes Vibrato Longitudinal Rolling ViewPager Effect

Use RecyclerView to realize the effect of Douyin longitudinal scrolling ViewPager for your reference. The specific contents are as follows

Override LinearLayoutManager and use PagerSnapHelper in the onAttachedToWindow method to set the RecyclerView entry load mode to 1 page per scroll

class MyLinearLayoutManager : LinearLayoutManager {

  private lateinit var mPagerSnapHelper: PagerSnapHelper
  private var mOnViewPagerListener: OnViewPagerListener? = null
  private lateinit var mRecyclerView: RecyclerView
  private var mDrift: Int = 0// Displacement, which is used to judge the moving direction 

  constructor(context: Context) : this(context, OrientationHelper.VERTICAL)
  constructor(context: Context, orientation: Int) : this(context, orientation, false)
  constructor(context: Context, orientation: Int, reverseLayout: Boolean) : super(context, orientation, reverseLayout) {
    mPagerSnapHelper = PagerSnapHelper()
  }

  override fun onAttachedToWindow(view: RecyclerView) {
    super.onAttachedToWindow(view)
    mPagerSnapHelper.attachToRecyclerView(view)// Settings RecyclerView Every scroll 1 Page 
    mRecyclerView = view
    mRecyclerView.addOnChildAttachStateChangeListener(mChildAttachStateChangeListener)
  }


  /**
   *  Change of sliding state 
   *  Slow drag -> SCROLL_STATE_DRAGGING
   *  Quick scroll -> SCROLL_STATE_SETTLING
   *  Idle state -> SCROLL_STATE_IDLE
   * @param state
   */
  override fun onScrollStateChanged(state: Int) {
    if (state == RecyclerView.SCROLL_STATE_IDLE){
      val viewIdle = mPagerSnapHelper.findSnapView(this)
      val positionIdle = getPosition(viewIdle!!)
      if (mOnViewPagerListener != null && childCount == 1) {
        mOnViewPagerListener!!.onPageSelected(positionIdle, positionIdle == itemCount - 1)
      }
    }
  }

  /**
   *  Called after the layout is complete 
   * @param state
   */
  override fun onLayoutCompleted(state: RecyclerView.State?) {
    super.onLayoutCompleted(state)
    if (mOnViewPagerListener != null) mOnViewPagerListener!!.onLayoutComplete()
  }

  /**
   *  Listen for relative offsets in the vertical direction 
   */
  override fun scrollVerticallyBy(dy: Int, recycler: RecyclerView.Recycler?, state: RecyclerView.State?): Int {
    this.mDrift = dy
    return super.scrollVerticallyBy(dy, recycler, state)
  }


  /**
   *  Listen for relative offset in horizontal direction 
   */
  override fun scrollHorizontallyBy(dx: Int, recycler: RecyclerView.Recycler?, state: RecyclerView.State?): Int {
    this.mDrift = dx
    return super.scrollHorizontallyBy(dx, recycler, state)
  }

  /**
   *  Set up listening 
   * @param listener
   */
  fun setOnViewPagerListener(listener: OnViewPagerListener) {
    this.mOnViewPagerListener = listener
  }

  private val mChildAttachStateChangeListener = object : RecyclerView.OnChildAttachStateChangeListener {
    override fun onChildViewAttachedToWindow(view: View) {
    }

    override fun onChildViewDetachedFromWindow(view: View) {
      if (mDrift >= 0) {
        if (mOnViewPagerListener != null) mOnViewPagerListener!!.onPageRelease(true, getPosition(view))
      } else {
        if (mOnViewPagerListener != null) mOnViewPagerListener!!.onPageRelease(false, getPosition(view))
      }

    }
  }

  interface OnViewPagerListener{
    /* Released monitor */
    fun onPageRelease(isNext: Boolean, position: Int)

    /* Selected monitor and determine whether to slide to the bottom */
    fun onPageSelected(position: Int, isBottom: Boolean)

    /* Layout completed monitoring */
    fun onLayoutComplete()
  }
}

Rewrite RecyclerView entry content main layout full screen fill

class MyImageView : ImageView {
  constructor(context: Context) : this(context, null!!)
  constructor(context: Context, attr: AttributeSet) : this(context, attr, 0)
  constructor(context: Context, attr: AttributeSet, defStyleAttr: Int) : super(context, attr, defStyleAttr)

  override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
    val width = View.getDefaultSize(0, widthMeasureSpec)
    val height = View.getDefaultSize(0, heightMeasureSpec)
    setMeasuredDimension(width, height)
  }

}

Code reference: LayoutManagerGroup