Xamarin Android可扩展的recycleview显示/隐藏图像指示器

Question

我能够在我的应用程序中成功实现可扩展的回收视图。我使用this来实现它。我有一个要求，即在加载项目时需要显示图像（向下箭头），展开项目时，图像应隐藏。点击该项目（即折叠）后，图像（向下箭头指示符）应该再次可见。如何实现？

这是我的RecycleViewAdaptor：

 public class UEventsRecycleViewAdaptor : RecyclerView.Adapter
{

    private List<DataType> listItems;
    private Context context;
    private LayoutInflater inflater;
    public event EventHandler<int> GroupClick;
    public event EventHandler<int> BttGroupClick;
    public event EventHandler<int> BttEntryClick;

    public UEventsRecycleViewAdaptor(Context context, List<DataType> listItems)
    {
        this.context = context;
        this.listItems = listItems;
        this.inflater = (LayoutInflater)context.GetSystemService(Context.LayoutInflaterService);
    }

    void GroupOnClick(int position)
    {
        if (GroupClick != null)
            GroupClick(this, position);
    }

    void BttGroupOnClick(int position)
    {
        if (BttGroupClick != null)
            BttGroupClick(this, position);
    }

    void BttEntryOnClick(int position)
    {
        if (BttEntryClick != null)
            BttEntryClick(this, position);
    }

    public override int ItemCount
    {
        get
        {
            return listItems.Count;
        }
    }

    public override int GetItemViewType(int position)
    {
        return listItems[position].GetItemType();
    }

    public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
    {
        DataType itemNode = listItems[position];

        if (itemNode.GetItemType() == 0)
        {
            UEventsGroupData group = itemNode as UEventsGroupData;
            UEventsGroupHolder groupHolder = holder as UEventsGroupHolder;

            groupHolder.txtEvents.Text= group.Events;

        }

        else if (itemNode.GetItemType() == 1)
        {
            UEventsEntryData entry = itemNode as UEventsEntryData;
            UEventsEntryHolder holderEntry = holder as UEventsEntryHolder;



            holderEntry.txtLocation.Text = entry.Location;
            holderEntry.txtStartDate.Text = entry.StartDate;
            holderEntry.txtEndDate.Text = entry.EndDate;

        }
    }

    public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
    {
        if (viewType == 0)
        {

            View entryView = inflater.Inflate(Resource.Layout.UEventsRecycler_Group, parent, false);

            return new UEventsGroupHolder(entryView, GroupOnClick, BttGroupOnClick);
        }
        else if (viewType == 1)
        {

            View sectionView = inflater.Inflate(Resource.Layout.UEventsRecycler_Entry, parent, false);
            return new UEventsEntryHolder(sectionView, BttEntryOnClick);
        }
        else
        {
            return null;
        }
    }
}

public class UEventsGroupHolder : RecyclerView.ViewHolder
{

    public TextView txtEvents { get; set; }

    public UEventsGroupHolder(View view, Action<int> groupClickListener, Action<int> bttClickListener) : base(view)
    {
        this.txtEvents = (TextView)view.FindViewById(Resource.Id.group_Event);


        view.Click += (sender, e) => groupClickListener(base.AdapterPosition);

    }
}

public class UEventsEntryHolder : RecyclerView.ViewHolder
{
    public TextView txtLocation { set; get; }
    public TextView txtStartDate { set; get; }
    public TextView txtEndDate { set; get; }


    public UEventsEntryHolder(View view, Action<int> bttEntryClickListener) : base(view)
    {
        this.txtLocation = (TextView)view.FindViewById(Resource.Id.Location);
        this.txtStartDate = (TextView)view.FindViewById(Resource.Id.s_StartDate);
        this.txtEndDate = (TextView)view.FindViewById(Resource.Id.s_EndDate);

    }
}

}

这是我的组布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView 
    android:id="@+id/group_Event"
     android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="" 
   android:layout_centerHorizontal="true" 
android:textColor="@color/white"/>
    <ImageView 
    android:id="@+id/imgArrowUE"
    android:src="@drawable/moredetails"
     android:layout_width="15dp"
    android:layout_height="15dp"
 android:layout_alignParentRight="true"/>

这是我的条目布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">
 <TextView
    android:id="@+id/LocationLabel"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Location :" 
android:textColor="@color/white"/>
<TextView
    android:id="@+id/Location"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="" 
    android:textColor="@color/white"
    android:layout_toRightOf="@id/LocationLabel"/>

 <TextView
    android:id="@+id/StartDateLabel"
    android:textColor="@color/white"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Start Date :" 
android:layout_below="@id/LocationLabel"/>
<TextView
    android:textColor="@color/white"
    android:id="@+id/s_StartDate"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="" 
    android:layout_below="@id/Location"
    android:layout_toRightOf="@id/StartDateLabel"/>

 <TextView
    android:textColor="@color/white"
    android:id="@+id/EndDateLabel"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="End Date :" 
android:layout_below="@id/StartDateLabel"/>
 <TextView
    android:textColor="@color/white"
    android:id="@+id/s_EndDate"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="" 
android:layout_below="@id/s_StartDate"
android:layout_toRightOf="@id/EndDateLabel"/>
</RelativeLayout>

这是我的网上论坛点击列表：

void OnGroupClick(object sender, int pos)
    {
        UEventsGroupData groupSelect = (UEventsGroupData)listItems[pos];

        if (groupSelect.items.Count == 0)
        {
            int count = 0;

            while (listItems.Count > pos + 1 && listItems[pos + 1].GetItemType() == 1)
            {
                groupSelect.items.Add(listItems[pos + 1]);
                listItems.RemoveAt(pos + 1);
                recyclerAdapter.NotifyItemRemoved(pos + 1);
                count++;
            }
        }
        else
        {
            int index = pos + 1;
            foreach (UEventsEntryData entryNode in groupSelect.items)
            {
                listItems.Insert(index, entryNode);
                recyclerAdapter.NotifyItemInserted(index);

                    index++;
            }

            groupSelect.items.Clear();

        }
    }