IssueTracker

View size enlarged after dragging. It went back normal after scrolling out and back.(Please check attached webm video)

RecyclerView Version is 1.2.1. Tested on Android Emulator 10.

Code: A draggable RecyclerView using a GridLayoutManager span count 3 and an ItemDecoration.

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(createRecyclerView())
    }

    private fun createRecyclerView(): RecyclerView {
        val rv = RecyclerView(this)
        rv.layoutManager = GridLayoutManager(this, 3).apply {
            spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
                override fun getSpanSize(position: Int): Int {
                    return 1
                }
            }
        }

        rv.adapter = RVAdapter((rv.layoutManager as GridLayoutManager).spanCount * 50 + 1)

        rv.addItemDecoration(object : RecyclerView.ItemDecoration() {
            override fun getItemOffsets(
                outRect: Rect,
                view: View,
                parent: RecyclerView,
                state: RecyclerView.State
            ) {
                super.getItemOffsets(outRect, view, parent, state)
                val position = parent.getChildAdapterPosition(view)
                if (position == RecyclerView.NO_POSITION) return
                val gridLayoutManager = parent.layoutManager as GridLayoutManager
                val spanSizeLookup = gridLayoutManager.spanSizeLookup
                val spanCount = gridLayoutManager.spanCount
                val spanIndex = spanSizeLookup.getSpanIndex(position, spanCount)
                outRect.set(0, 0, 0, 0)
                if (spanIndex % spanCount < spanCount - 1) { // not left one
                    outRect.right = 20
                }
                if (position >= spanCount) { // not first row
                    outRect.top = 20
                }
            }
        })

        ItemTouchHelper(object : ItemTouchHelper.SimpleCallback(
            ItemTouchHelper.UP or ItemTouchHelper.DOWN or ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT,
            0
        ) {
            override fun onMove(
                recyclerView: RecyclerView,
                viewHolder: RecyclerView.ViewHolder,
                target: RecyclerView.ViewHolder
            ): Boolean {
                (recyclerView.adapter as RVAdapter).onMove(viewHolder, target)
                //recyclerView.post { recyclerView.invalidateItemDecorations() } // doesn't work
                return true
            }

            override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
                // n/a
            }

        }).attachToRecyclerView(rv)

        return rv
    }

    class RVAdapter(val count: Int) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
        private val list: MutableList<String> = MutableList(count) { "[$it]" }

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
            return object : RecyclerView.ViewHolder(TextView(parent.context).apply {
                layoutParams = ViewGroup.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT
                )
                setBackgroundColor(Color.CYAN)
                setPadding(20)
                gravity = Gravity.CENTER
            }) {}
        }

        override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
            (holder.itemView as TextView).text = list[position]
        }

        override fun getItemCount(): Int {
            return count
        }

        fun onMove(holder: RecyclerView.ViewHolder, target: RecyclerView.ViewHolder) {
            val item = list.removeAt(holder.bindingAdapterPosition)
            list.add(target.bindingAdapterPosition, item)
            notifyItemMoved(holder.bindingAdapterPosition, target.bindingAdapterPosition)
        }
    }
}