I have RecyclerView Drag & Drop feature, but I'd like to do some calculations onDrop. When I put my expensiveFunction() in onMove() it's triggered at every position change until the drag is over. That's a big overkill. Is there a way to trigger function on drag end?
val itemTouchHelper = ItemTouchHelper(simpleCallback)
itemTouchHelper.attachToRecyclerView(recyclerView)
private var simpleCallback = object : ItemTouchHelper.SimpleCallback(ItemTouchHelper.UP.or(ItemTouchHelper.DOWN), 0) {
override fun onMove(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder, target: RecyclerView.ViewHolder): Boolean {
val startPosition = viewHolder.absoluteAdapterPosition
val endPosition = target.absoluteAdapterPosition
Collections.swap(itemList, startPosition, endPosition)
recyclerView.adapter?.notifyItemMoved(startPosition, endPosition)
expensiveFunction()
return true
}
}
You could override onSelectedChanged() which get called when the ViewHolder swiped or dragged by the ItemTouchHelper.
To catch the drop action examine the actionState value to be ItemTouchHelper.ACTION_STATE_IDLE:
override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
super.onSelectedChanged(viewHolder, actionState)
when (actionState) {
// when the item is dropped
ItemTouchHelper.ACTION_STATE_IDLE -> {
Log.d(TAG, "Item is dropped")
}
}
}