仿淘宝菜单栏线条滚动

布局

布局代码
<LinearLayout
    android:orientation="vertical"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

    </android.support.v7.widget.RecyclerView>
    <RelativeLayout
        android:id="@+id/parent_layout"
        android:layout_gravity="center"
        android:layout_width="100dp"
        android:layout_height="5dp"
        android:background="@drawable/bg_fast_view">
        <View
            android:id="@+id/main_line"
            android:layout_width="30dp"
            android:layout_height="5dp"
            android:background="@drawable/bg_scroll_bar"
            android:layout_centerVertical="true"/>
    </RelativeLayout>

</LinearLayout>

adapter代码 主要是设置item的宽度。
public class IndexMenuAdapter extends RecyclerView.Adapter<IndexMenuAdapter.ViewHolder> {
    private List<MenuBean.DataEntity> data=new ArrayList<>();
    private Context mContext;
    private int width;

    public IndexMenuAdapter(Context context) {
        mContext=context;
        width = (ScreenUtils.getScreenW(context) - ScreenUtils.dip2px(context,20)) / 5;
    }

    public List<MenuBean.DataEntity> getData() {
        return data;
    }

    public void setData(List<MenuBean.DataEntity> data) {
        this.data = data;
        notifyDataSetChanged();
    }


    @Override
    public IndexMenuAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View contentView = LayoutInflater.from(parent.getContext()).inflate(R.layout.index_menu_item, parent, false);
        IndexMenuAdapter.ViewHolder viewHolder = new IndexMenuAdapter.ViewHolder(contentView);
        ViewGroup.LayoutParams params = contentView.getLayoutParams();
        params.width = width;
        contentView.setLayoutParams(params);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        RequestOptions options=new RequestOptions();
        options.placeholder(R.mipmap.index_zwt_icon);
        options.error(R.mipmap.index_zwt_icon);
        Glide.with(mContext).load(data.get(position).getImg()).apply(options).into(holder.icon);
        holder.name.setText(data.get(position).getName());
    }

    @Override
    public int getItemCount() {
        if (data!=null) {
            return data.size();
        }else{
            return 0;
        }
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        private ImageView icon;
        private TextView name;

        public ViewHolder(View itemView)
        {
            super(itemView);
            icon = (ImageView) itemView.findViewById(R.id.index_menu_icon);
            name = (TextView) itemView.findViewById(R.id.index_menu_name);
        }
    }
}

滑动主要代码
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        super.onScrollStateChanged(recyclerView, newState);

    }

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

        //整体的总宽度，注意是整体，包括在显示区域之外的。
        int temp=mRecyclerView.computeHorizontalScrollRange();
        if (temp>range){
            range=temp;
        }
        int offset = mRecyclerView.computeHorizontalScrollOffset();
        int extent = mRecyclerView.computeHorizontalScrollExtent();

        float proportion = (float) (offset*1.0 / (range-extent));
        //计算滚动条宽度
        float transMaxRange = mLayout.getWidth() - mLineView.getWidth();
        //设置滚动条移动
        mLineView.setTranslationX(transMaxRange * proportion);
        Log.e("scrll",transMaxRange+"---"+range+"---"+"---"+proportion+"---"+offset+"----"+extent);

    }

});