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

Question

我使用RecyclerView的ItemTouchHelper来改变顺序(拖拽&，我只想移动列表的一部分。我不想在某个指标之后移动。我如何用一个RecyclerView来处理它?

如果我再解释一下我想做什么，活动项向上排序，非活动项向下排序。只有激活的物品才会改变顺序。现在，当我拖动一个活动项时，它会向下移动到非活动项的区域，但我想阻止它向下移动。我该怎么做呢?

更新

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

使用ItemTouchHelper.SimpleCallback和覆盖getDragDirs和onMove方法:

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
}
}

在getDragDirs上返回0防止非活动项目选择，当在onMove上返回false时，在拖动时阻止项目移动。.