如何使 RecyclerView 的 ItemTouchHelper 仅在列表的一部分上工作（拖放）

Question

I use RecyclerView's ItemTouchHelper to change the order(drag & drop),And I want to move only a part of the list. I don't want to move after a certain index. How can I handle it with one RecyclerView?

If I explain a little more about what I want to make, The active items are sorted up and the non-active items are sorted down. And only the activated items will shift the order. Right now, when I drag an active item, it goes down to the area of the non-active item, but I want to prevent it from going down. How can I do it?

UPDATE

open class SimpleItemTouchHelperCallback(private val mAdapter: ItemTouchHelperAdapter) :
    ItemTouchHelper.Callback() {

    private var isLongPressDrag = true

    fun setLongPressDragEnable(isLongPressDrag: Boolean) {
        this.isLongPressDrag = isLongPressDrag
    }

    override fun isLongPressDragEnabled() = isLongPressDrag

    override fun getMovementFlags(
        recyclerView: RecyclerView,
        viewHolder: RecyclerView.ViewHolder
    ): Int {
        val dragFlags = ItemTouchHelper.UP or ItemTouchHelper.DOWN
        val swipeFlags = 0
        return makeMovementFlags(dragFlags, swipeFlags)
    }

    override fun onMove(
        recyclerView: RecyclerView,
        viewHolder: RecyclerView.ViewHolder,
        target: RecyclerView.ViewHolder
    ): Boolean {
        return mAdapter.onItemMove(viewHolder.adapterPosition, target.adapterPosition)
    }

    override fun onSwiped(viewHolder: RecyclerView.ViewHolder, i: Int) {
        mAdapter.onItemDismiss(viewHolder.adapterPosition)
    }

}

Answer 1

Use ItemTouchHelper.SimpleCallback and override getDragDirs and onMove methods:

ItemTouchHelper.SimpleCallback(
        UP or DOWN,
        0
) {
    override fun getDragDirs(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder): Int {
        val selectedPosition = viewHolder.adapterPosition
        val isActive: Boolean = // retrieve your model from list and check its active state
        return if (isActive) super.getDragDirs(recyclerView, viewHolder) else 0
    }
    override fun onMove(
            recyclerView: RecyclerView,
            viewHolder: RecyclerView.ViewHolder,
            target: RecyclerView.ViewHolder,
    ): Boolean {
        val toPosition = target.adapterPosition
        val isActiveTarget: Boolean = // retrieve your target model from list and check its active state
        if (!isActiveTarget) return false
        val fromPosition = viewHolder.adapterPosition
        moveItem(fromPosition, toPosition)
        return true
    }
}

Returning 0 on getDragDirs prevents inactive item selection , while returning false on onMove prevents item movement while dragging .