Android-RecyclerView：通过刷卡删除项目

Question

我有一个RecyclerView，这些物品应该在刷卡后移除。我用ItemTouchHelper类解决了这个问题。在onchildraw方法中，我设置了一个红色背景，在列表项后面滑动时出现。最重要的是，在正确的网站上有一个垃圾图标。它工作正常，但是如果你开始刷卡，但不刷卡到底，然后又刷卡回到正常位置，垃圾桶的图标不会消失。但是，它只有在我滑动所选项目时才会消失，而不是在普通项目上。

下面是ItemTouchHelper类的代码：

ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {

        @Override
        public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
            return false;
        }

        @Override
        public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
            int position = viewHolder.getAdapterPosition();
            rvAdapter.removeItem(position);
        }

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

            Bitmap icon;
            if(actionState == ItemTouchHelper.ACTION_STATE_SWIPE){

                View itemView = viewHolder.itemView;
                float height = (float) itemView.getBottom() - (float) itemView.getTop();
                float marginRight = 10;

                paint.setColor(Color.parseColor("#D32F2F"));
                RectF background = new RectF((float) itemView.getRight() + dX, (float) itemView.getTop(),(float) itemView.getRight(), (float) itemView.getBottom());
                c.drawRect(background,paint);
                icon = BitmapFactory.decodeResource(getResources(), R.drawable.ic_delete_forever);
                RectF icon_dest = new RectF((float) itemView.getRight() - marginRight - height, itemView.getTop(), itemView.getRight() - marginRight, itemView.getBottom());
                c.drawBitmap(icon,null,icon_dest,paint);

            }

            super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);

        }

    };

有人知道如何在取消刷卡时删除图标吗？还是有类似于z指数的东西？因为当我刷回所选项目时，垃圾箱图标会消失在项目下。但是，当我滑动一个普通项目时，图标位于项目上方，然后图标停留在那里。

Answer 1

@Override
public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
    if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
        Bitmap icon;
        Paint paint = new Paint();

        View itemView = viewHolder.itemView;
        float height = (float) itemView.getBottom() - (float) itemView.getTop();
        float width = height / 3;

        if (dX < 0) {
            paint.setColor(Color.parseColor("#D32F2F"));

            RectF background = new RectF(
                    (float) itemView.getRight() + dX, (float) itemView.getTop(),
                    (float) itemView.getRight(), (float) itemView.getBottom());
            c.drawRect(background, paint);

            icon = BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_delete);
            RectF iconDest = new RectF(
                    (float) itemView.getRight() - 2 * width, (float) itemView.getTop() + width,
                    (float) itemView.getRight() - width, (float) itemView.getBottom() - width);
            c.drawBitmap(icon, null, iconDest, paint);
        }

    } else if (actionState == ItemTouchHelper.ACTION_STATE_DRAG) {
        final float alpha = ALPHA_FULL - Math.abs(dY) / (float) viewHolder.itemView.getHeight();
        viewHolder.itemView.setAlpha(alpha);
        viewHolder.itemView.setTranslationY(dY);
    }

    super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
}