当 ViewHolder 到达 RecyclerView 的顶部或底部时如何停止拖动

如何解决当 ViewHolder 到达 RecyclerView 的顶部或底部时如何停止拖动

我有一个支持拖放的 recyclerView。当我将一个 viewHolder 拖到列表的末尾时，它会一直拖过最后一个索引。让它在到达终点时停止拖动的正确方法是什么？现在，当“放下”时，它会弹回到 RecyclerView 中的最后一个位置。

这是用recyclerView的height="match_parent"

这是与 recyclerView 的 height="wrap_content"

阅读此 post 后，我尝试在 itemtouchhelper 的 onChildDraw 方法中阻止这种行为。我试图在最后一个索引处停止拖动的三件事都有效，但交换动画根本不流畅。处理这个问题的正确方法是什么？此外，这是 itemtouchhelper/recyclerView 的标准行为（不要在列表的开头/结尾停止拖动）？我发现很难相信默认行为允许这样做，我想知道是否是我的实现导致了这种情况。

@Override
public void onChildDraw(@NonNull Canvas canvas,@NonNull RecyclerView recyclerView,@NonNull RecyclerView.ViewHolder viewHolder,float dX,float dY,int actionState,boolean isCurrentlyActive) {

  if(actionState == itemtouchhelper.ACTION_STATE_DRAG) {

    // FirsT THING I TRIED
    // This works but slows the swapping animations down. When fast dragging an item down to the
    // bottom it's like it hit a brick wall and the viewHolder bounces upward a little before settling in
    // the last position
    if(viewHolder.getAdapterPosition() == recyclerLastIndex || viewHolder.getAdapterPosition() == 0) {
            return;
    }

    // SECOND THING I TRIED
    // This also works but I lose the fluid swapping animations while dragging. The swap is very abrupt.
    recyclerView.getLocationOnScreen(posXY);  // method uses a 2 element array (posXY) to store X and Y coordinates
    int yPosOfRecycler = posXY[1]; // Y coordinate is stored in the second position
    viewHolder.itemView.getLocationOnScreen(posXY);
    int yPosOfViewHolder = posXY[1];
    if(yPosOfViewHolder > yPosOfRecycler) {
      return;
    }

    // THIRD THING I TRIED
    // Works but swapping animations are also lost 
    if(!recyclerView.canScrollVertically(1)) {
            return;
    }

    // If I comment out the code in the 3 approaches above,the swapping animations are beautifully
    // smooth,but will allow dragging past the boundaries of the recyclerView  
    super.onChildDraw(canvas,recyclerView,viewHolder,dX,dY,actionState,isCurrentlyActive);
  }
}