Question

我正在尝试在Drag / Touch上突出显示水平 RecyclerView 的项目。在Instagram中，他们实现了这一点，以便在上传视频时选择缩略图。如果你知道怎么做，请建议。

Answer 1

您可以为选中的项目自定义ItemTouchHelperViewHolder类并清除拖放：

public interface ItemTouchHelperViewHolder {
    void onItemSelected(int adapterPosition);
    void onItemClear(int adapterPosition, int position);
}

这是CustomSimpleTouchListner类：

@Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        // We only want the active item to change
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            if (viewHolder instanceof ItemTouchHelperViewHolder) {
                // Let the view holder know that this item is being moved or dragged
                ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
                itemViewHolder.onItemSelected();
            }
        }

        super.onSelectedChanged(viewHolder, actionState);
    }

    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);

        viewHolder.itemView.setAlpha(ALPHA_FULL);

        if (viewHolder instanceof ItemTouchHelperViewHolder) {
            // Tell the view holder it's time to restore the idle state
            ItemTouchHelperViewHolder itemViewHolder = (ItemTouchHelperViewHolder) viewHolder;
            itemViewHolder.onItemClear(fromPos, toPos);
        }
    }

在Recycleview ViewHolder中扩展此类

public class ViewHolder extends RecyclerView.ViewHolder implements ItemTouchHelperViewHolder {

        public ViewHolder(View itemView) {
            super(itemView);
         }

        @Override
        public void onItemSelected(int adapterPosition) {
            itemView.setBackgroundColor(activity.getResources().getColor(R.color.presented_color));
        }

        @Override
        public void onItemClear(int adapterPosition, int position) {
            itemView.setBackgroundColor(activity.getResources().getColor(android.R.color.transparent));
        }
    }

Answer 2

我没有去过Instagram看你真正想要的东西，但似乎你应该使用setOnTouchListener突出显示特定的单元格。您将收到有关每个单元格的触摸事件的通知。请查看以下链接以获取示例。

how to highlight the selected Item of Recycler View?

Answer 3

https://stackoverflow.com/a/35360331/5098486

这个答案可以很容易地修改recyclerView中的选定项目。

@Override

public void onBindViewHolder(final ViewHolder holder, final int position) {

    Item item = items.get(position);

    if(selected_position == position){
        // Here I am just highlighting the background
        holder.itemView.setBackgroundColor(Color.GREEN);
    }else{
        holder.itemView.setBackgroundColor(Color.TRANSPARENT);
    }

    holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            // Updating old as well as new positions
            notifyItemChanged(selected_position);
            selected_position = position;
            notifyItemChanged(selected_position);

            // Do your another stuff for your onClick
        }
    });
}

如何在Instagram上拖动/触摸时突出显示Recycler视图项？

3 个答案: