Using ItemTouchHelper to Move an Item Multiple Spaces

Question

I have created a RecyclerView, RecyclerView.Callback, and RecyclerView.ItemTouchHelper that allows the user to reorder the items by dragging. This is mostly successful, except for the fact that it only allows me to drag the item 1 space at a time, even if I do not lift my finger. How can I fix this?

Answer 1

Hello,​

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except for the fact that it only allows me to drag the item 1 space at a time, even if I do not lift my finger.

Hi, how did you create the touch-drag function for the recyclerView? I created a basic demo to test the function, it works as expeted on my side. Here is the sample code:

MainActivity class

   public class MainActivity : AppCompatActivity, IOnStartDragListener  
   {  
       public static MainActivity Instance;  
       RecyclerView recyclerView;  
       RecyclerView.LayoutManager layoutManager;  
       public static ObservableCollection<TestModel> data;  
       private ItemTouchHelper _mItemTouchHelper;  
     
       protected override void OnCreate(Bundle savedInstanceState)  
       {  
           base.OnCreate(savedInstanceState);  
           Xamarin.Essentials.Platform.Init(this, savedInstanceState);  
           SetContentView(Resource.Layout.activity_main);  
     
           Instance = this;  
     
           recyclerView = FindViewById<RecyclerView>(Resource.Id.test_recyclerView);  
           layoutManager = new LinearLayoutManager(this);  
     
           data = new ObservableCollection<TestModel>();  
           data.Add(new TestModel { content = "item_1" });  
           data.Add(new TestModel { content = "item_2" });  
           data.Add(new TestModel { content = "item_3" });  
     
           TestAdapter testAdapter = new TestAdapter(data, this);  
           recyclerView.SetLayoutManager(layoutManager);  
           recyclerView.SetAdapter(testAdapter);  
     
           ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(testAdapter);  
           _mItemTouchHelper = new ItemTouchHelper(callback);  
           _mItemTouchHelper.AttachToRecyclerView(recyclerView);  
       }  
     
       public void OnStartDrag(RecyclerView.ViewHolder viewHolder)  
       {  
           _mItemTouchHelper.StartDrag(viewHolder);  
       }  
   }  

ViewHolder and Adapter class

   public class TestViewHolder : RecyclerView.ViewHolder  
   {  
       public TextView ItemText { get; set; }  
       public TestViewHolder(View itemView) : base(itemView)  
       {  
           ItemText = itemView.FindViewById<TextView>(Resource.Id.itemText);  
       }  
   }  
     
   public class TestAdapter : RecyclerView.Adapter, ITemTouchHelperAdapter, IOnLongClickListener  
   {  
       public ObservableCollection<TestModel> list;  
       TestViewHolder viewHolder;  
       private readonly IOnStartDragListener dragStartListener;  
     
       public TestAdapter(ObservableCollection<TestModel> list, IOnStartDragListener dragStartListener)  
       {  
           this.list = list;  
           this.dragStartListener = dragStartListener;  
       }  
       public override int ItemCount  
       {  
           get  
           {  
               return list.Count;  
           }  
       }  
       public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)  
       {  
           viewHolder = holder as TestViewHolder;  
           viewHolder.ItemText.Text = list[position].content;  
       }  
       public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)  
       {  
           View itemView = LayoutInflater.From(MainActivity.Instance).Inflate(Resource.Layout.recyclerView_itemLayout, parent, false);  
           TestViewHolder viewHolder = new TestViewHolder(itemView);  
           return viewHolder;  
       }  
       public bool OnItemMove(int fromPosition, int toPosition)  
       {  
           var tempPlanResource = list[fromPosition];  
           list[fromPosition] = list[toPosition];  
           list[toPosition] = tempPlanResource;  
           MainActivity.data = list;  
           NotifyItemMoved(fromPosition, toPosition);  
           return true;  
       }  
       public void OnItemDismiss(int position)  
       {  
           var item = list[position];  
           list.Remove(item);  
           NotifyItemRemoved(position);  
       }  
       public bool OnLongClick(View v)  
       {  
           dragStartListener.OnStartDrag(viewHolder);  
           return true;  
       }  
   }  
     
   public class TestModel  
   {  
       public string content { get; set; }  
   }  

Related interfaces and touch callback class

   public interface IOnStartDragListener  
   {  
       void OnStartDrag(RecyclerView.ViewHolder viewHolder);  
   }  
     
   public interface ITemTouchHelperAdapter  
   {  
       bool OnItemMove(int fromPosition, int toPosition);  
       void OnItemDismiss(int position);  
   }  
     
   public class SimpleItemTouchHelperCallback : ItemTouchHelper.Callback  
   {  
       private readonly ITemTouchHelperAdapter _mAdapter;  
       public SimpleItemTouchHelperCallback(ITemTouchHelperAdapter adapter)  
       {  
           _mAdapter = adapter;  
       }  
       public override int GetMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder)  
       {  
           const int dragFlags = ItemTouchHelper.Up | ItemTouchHelper.Down;  
           const int swipeFlags = ItemTouchHelper.ActionStateIdle;  
           return MakeMovementFlags(dragFlags, swipeFlags);  
       }  
       public override bool OnMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target)  
       {  
           if (viewHolder.ItemViewType != target.ItemViewType)  
           {  
               return false;  
           }  
           _mAdapter.OnItemMove(viewHolder.AdapterPosition, target.AdapterPosition);  
           return true;  
       }  
       public override void OnSwiped(RecyclerView.ViewHolder viewHolder, int direction)  
       {  
           _mAdapter.OnItemDismiss(viewHolder.AdapterPosition);  
       }  
   }  

I found this solution by searching on the keywords ReOrder the list items by drag and drop in xamarin android using RecyclerView to check the related documentation.

Best Regards,

Jarvan Zhang

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