Question

我正在将一些AnimatorSet应用于recyclerView的项目，

recyclerView适配器：

class MyAdapter(...) : 
androidx.recyclerview.widget.RecyclerView.Adapter<MyAdapter.ViewHolder>() {

override fun onCreateViewHolder(parent: ViewGroup, p1: Int): ViewHolder {
    return ViewHolder(...)
    }

override fun onBindViewHolder(p0: ViewHolder, p1: Int) {
    p0.bind(...)
    }


inner class ViewHolder(itemView: View,...) : 
androidx.recyclerview.widget.RecyclerView.ViewHolder(itemView) {

fun bind(...) {
        ...
        animateItemView(itemView)
        ...
}
}
}

animateItemView函数

        fun animateItemView(itemView: View) {
        //hide the itemView
        itemView.alpha = 0f

        //moving the itemView down 400f
        ObjectAnimator.ofFloat(itemView, "translationY", 0f, 400f)
            .apply { duration = 1L }.start()

        //show
        //itemView.alpha = 1f

        //moving the itemView up 400f
        val translateUp = ObjectAnimator.ofFloat(itemView, "translationY", 400f, 0f)
            .apply {
                duration = 1000L
                interpolator = AnticipateOvershootInterpolator(2f)
            }

        //animating alpha
        val fade = ValueAnimator.ofFloat(0f, 1f)
            .apply {
                addUpdateListener {
                    itemView.alpha = this.animatedValue as Float
                }
                duration = 400L
            }

        //applying
        AnimatorSet().apply { playTogether(translateUp, fade) }.start()


    }

结果：

当然，当向上滚动itemView时仍然向上滑动，是否可以应用不同的动画向上/向下滚动，还是有更好的方法？

Answer 1

我不知道为什么每个人都对将所有内容放入RecyclerView.Adapter着迷。

您可以将此动画注入RecyclerView.LayoutManager中，因为它知道添加视图的确切时间和位置：

open class FadeInLinearLayoutManager : LinearLayoutManager {
    constructor(context: Context?) : super(context)
    constructor(context: Context?, orientation: Int, reverseLayout: Boolean) : super(context, orientation, reverseLayout)
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int, defStyleRes: Int) : super(context, attrs, defStyleAttr, defStyleRes)

    private val enterInterpolator = AnticipateOvershootInterpolator(2f)

    override fun addView(child: View, index: Int) {
        super.addView(child, index)
        val h = 400f
        // if index == 0 item is added on top if -1 it's on the bottom
        child.translationY = if(index == 0) -h else h
        // begin animation when view is laid out
        child.alpha = 0.3f
        child.animate().translationY(0f).alpha(1f)
                .setInterpolator(enterInterpolator)
                .setDuration(1000L)
    }
}

然后将其用作布局管理器：

recyclerView.layoutManager = FadeInLinearLayoutManager(context)

动画回收器查看项目

1 个答案: