Блог

Я хочу установить видимость панели поиска видимой, если список прокручивается вниз, и видимость пропала, если список прокручивается вверх с помощью addOnScrollListener в Recyclerview.

применение условия dy> 0 и dy<0 вызывает мерцание. Пожалуйста, помогите мне.

  recyclerOverView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            if (dy < 0)
                exFab.shrink();
            else if (dy > 0)
                exFab.extend();
        }

        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
        }
    });
}
  

проверьте это, надеюсь, это сработает.

 class MainActivity : AppCompatActivity() {
private val TAG = "MainActivity"
private val SEARCH_BAR_HEIGHT = dpToPx(70)  //replace it with view height

private val scrollListener = object : RecyclerView.OnScrollListener() {
    var isSearchVisible = false
    var isAnimating = false
    var lastPosition = -1
    var currentPosition = 0
    var isScrollingUp = false

    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        currentPosition =
            (recyclerView.layoutManager as LinearLayoutManager).findFirstCompletelyVisibleItemPosition()
        Log.d(TAG, "current position = $currentPosition last Position = $lastPosition")

        if (currentPosition < lastPosition) {
            //scroll up
            if (!isScrollingUp || isSearchVisible || isAnimating) {
                isScrollingUp = true
                lastPosition = currentPosition
                return
            }

            isAnimating = true
            isScrollingUp = true

            animate(searchView, 0, SEARCH_BAR_HEIGHT, object : AnimationListener {
                override fun onAnimationCompleted() {
                    isAnimating = false
                    isSearchVisible = true
                }

                override fun onAnimationCanceled() {
                    isAnimating = false
                }
            })
        } else if (currentPosition > lastPosition) {
            //scroll down
            if (isScrollingUp || !isSearchVisible || isAnimating) {
                isScrollingUp = false
                lastPosition = currentPosition
                return
            }

            isAnimating = true
            isScrollingUp = false
            animate(searchView, SEARCH_BAR_HEIGHT, 0, object : AnimationListener {
                override fun onAnimationCompleted() {
                    isAnimating = false
                    isSearchVisible = false
                    searchView.visibility = View.GONE
                }

                override fun onAnimationCanceled() {
                    isAnimating = false
                }
            })
        }
        lastPosition = currentPosition
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main2)

    recyclerView.apply {
        layoutManager = LinearLayoutManager(this@MainActivity)
        adapter = ItemAdapter()
        addOnScrollListener(scrollListener)
    }
}

fun animate(view: View, fromHeight: Int, toHeight: Int, callback: AnimationListener?) {
    view.clearAnimation()
    view.visibility = View.VISIBLE
    val valueAnimator: ValueAnimator = ValueAnimator.ofInt(fromHeight, toHeight)

    valueAnimator.addUpdateListener { animation ->
        val layoutParam = view.layoutParams
        layoutParam.height = animation.animatedValue as Int
        view.layoutParams = layoutParam
    }

    valueAnimator.addListener(object : Animator.AnimatorListener {
        override fun onAnimationRepeat(p0: Animator?) {
        }

        override fun onAnimationEnd(p0: Animator?) {
            callback?.onAnimationCompleted()
        }

        override fun onAnimationCancel(p0: Animator?) {
            callback?.onAnimationCanceled()
        }

        override fun onAnimationStart(p0: Animator?) {
        }

    })

    valueAnimator.interpolator = DecelerateInterpolator()
    valueAnimator.duration = 200
    valueAnimator.start()
}

interface AnimationListener {
    fun onAnimationCompleted()
    fun onAnimationCanceled()
}
  

}