RecyclerView SnapHelper - 如何更改捕捉和未捕捉项目的背景？

Question

我正在使用带有水平 LinearLayoutManager 的 recyclerview。当项目在中间对齐时，我想更改 recyclerview 项目颜色。

所以我使用了 LinearSnapHelper。

目前，之前捕捉的每个项目都保持捕捉的背景颜色。所以我做了什么，我创建了全局变量 snappedPosition 并将其设置为 0，因此默认情况下将捕捉 recyclerview 的第一项。

然后我在适配器的 onBindViewHolder 中调用了 snappedPosition 并将项目的颜色更改为 recyclerview 中每个项目的默认颜色，除了与捕捉项目位置相同的项目。但是在 notifyItemChanged(position) 我得到了：

java.lang.IllegalStateException：RecyclerView 正在计算布局或滚动 android.support.v7.widget.RecyclerView 时无法调用此方法

片段内的代码：

val snapHelper: LinearSnapHelper = LinearSnapHelper()
var snappedPosition: Int = 0

        addressRecyclerView = view.findViewById<RecyclerView>(R.id.address_recycler_view).apply {

            setHasFixedSize(true)
            layoutManager = viewManager
            adapter = viewAdapter

        }

        snapHelper.attachToRecyclerView(addressRecyclerView)
        addressRecyclerView.onFlingListener = snapHelper
        itemOffsetDecoration = ItemOffsetDecoration(context, R.dimen.address_recyclerview_padding)
        addressRecyclerView.addItemDecoration(itemOffsetDecoration)

        addressRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrollStateChanged(recyclerView: RecyclerView?, newState: Int) {
                if (newState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE) {
                    val centerView = snapHelper.findSnapView(viewManager)
                    if (centerView != null) {

                        snappedPosition = addressRecyclerView.getChildAdapterPosition(centerView)
                    }
                }
            }
        })

onBindViewHolder 内的代码

addressList[position].let {


                if (position == fragment.snappedPosition){
                    holder.itemViewLayout.setBackgroundResource(R.drawable.payment_button_active)
                    notifyItemChanged(position)
                } else {
                    holder.itemViewLayout.setBackgroundResource(R.drawable.payment_button_inactive)
                    notifyItemChanged(position)
                }

            }

我想要实现的类似于这个图像示例：

更新：颜色变化变体的代码示例（仍然无效）：

addressRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrollStateChanged(recyclerView: RecyclerView?, newState: Int) {
                if (newState == AbsListView.OnScrollListener.SCROLL_STATE_IDLE) {
                    val centerView = snapHelper.findSnapView(addressRecyclerView.layoutManager)
                    if (centerView != null) {
                        for(item in 0 until addressRecyclerView.layoutManager.childCount){
                            val holder: RecyclerView.ViewHolder = addressRecyclerView.findViewHolderForAdapterPosition(item)
                            holder.itemView.setBackgroundResource(R.drawable.payment_button_inactive)
                        }
                        centerView.setBackgroundResource(R.drawable.payment_button_active)

                    }
                }
            }
        })

Answer 1

尝试以下操作来跟踪当前捕捉的视图，设置适当的背景并在移动RecyclerView. 这避免了对适配器进行修改。

    mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
            if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                View view = mSnapHelper.findSnapView(recyclerView.getLayoutManager());
                view.setBackgroundColor(getResources().getColor(android.R.color.holo_green_light));
                mLastSnappedView = view;
            } else if (mLastSnappedView != null) {
                mLastSnappedView.setBackgroundColor(getResources().getColor(android.R.color.white));
                mLastSnappedView = null;
            }
        }

        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        }
    });