如何像Instagram一样在Drag / Touch上突出显示Recycler视图项？

Question

I am trying to highlight the item of my horizontal RecyclerView on Drag/Touch.Like in Instagram they implemented this for selecting thumbnail while uploading the video. Please suggest if you know how to do this.

Answer 1

You can make you custom ItemTouchHelperViewHolder Class for Item selected and clear for drag and drop:

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

This is CustomSimpleTouchListner Class:

@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);
        }
    }

Extend this class in your Recycleview ViewHolder

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

I haven't gone to Instagram to see what you really want, but it seems like you should highlight the specific cell using the setOnTouchListener. You'll get notifications of touch events for each cell. check out the link below for an example.

how to highlight the selected Item of Recycler View?

Answer 3

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

This answer makes it really easy to modify the selected item in your recyclerView.

@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
        }
    });
}