ViewPager2OnPageSelected.kt

mViewpager.registerOnPageChangeCallback(object: OnPageChangeCallback() {
    override fun onPageSelected(position: Int) {
        // height를 wrap_content가 되도록 설정
        val view = (getChildAt(0) as RecyclerView).layoutManager?.findViewByPosition(position) // 표시된 아이템의 뷰 객체
        view?.post { // UI 스레드에서 해당 뷰 height를 다시 설정해서 그려줌
            val wMeasureSpec =
                View.MeasureSpec.makeMeasureSpec(view.width, View.MeasureSpec.EXACTLY)
            val hMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
            view.measure(wMeasureSpec, hMeasureSpec)
            
            if (getChildAt(0).layoutParams.height != view.measuredHeight) {
                getChildAt(0).layoutParams = (getChildAt(0).layoutParams).also { lp ->
                    lp.height = view.measuredHeight
                }
            }
        }
    }
})