Question

我试图在刷卡时在RecyclerView的一行下面绘制一个图标，类似于Gmail或收件箱应用。我实现了颜色，但我想绘制的Bitmap正在躲避我。我正在使用https://material.io/icons/网站上的删除图标。我将其作为SVG下载并将其作为XML文件导入我的drawables文件夹。我的代码如下：

private Paint p = new Paint();
private ItemTouchHelper.SimpleCallback ithSC = 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) {
        fileData.remove(viewHolder.getAdapterPosition());
        adapter.notifyDataSetChanged();
    }

    @Override
    public void onChildDraw(Canvas c, RecyclerView rv, RecyclerView.ViewHolder vh, float dx, float dy, int actionState, boolean isCurrentlyActive) {

        Bitmap b = BitmapFactory.decodeResource(getResources(), R.drawable.ic_delete);
        if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {

            // this gets the RecyclerView row from the ViewHolder
            View itemView = vh.itemView;

            // p is a Paint object, setting the color
            p.setColor(Color.RED);
            c.drawRect(dx, (float) itemView.getTop(), (float) itemView.getRight(), (float) itemView.getBottom(), p);

            super.onChildDraw(c, rv, vh, dx,dy, actionState, isCurrentlyActive);
        }
    }
};

当我运行应用程序时，logcat会显示消息：

D/skia: ---- fAsset->read(8192) returned 0
D/skia: --- SkAndroidCodec::NewFromStream returned null

为什么BitmapFactory.decodeResource（）调用返回一个null对象，如何修复它？

提前致谢

更新：

我尝试过其他一些东西，这是我更新的代码。其中一个重大变化是图标是PNG而不是XML

public void onChildDraw(Canvas c, RecyclerView rv, RecyclerView.ViewHolder vh, float dx, float dy, int actionState, boolean isCurrentlyActive) {

        if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {

            // this gets the RecyclerView row from the ViewHolder
            View itemView = vh.itemView;

            // get the width and height
            float height = itemView.getHeight();
            float width = height/3;

            // p is a Paint object, setting the color
            p.setColor(Color.RED);
            c.drawRect(dx, (float) itemView.getTop(), (float) itemView.getRight(), (float) itemView.getBottom(), p);

            Bitmap b = BitmapFactory.decodeResource(MainActivity.this.getResources(), R.drawable.ic_delete);
            RectF destination = new RectF((float) itemView.getRight() - 2*width , (float) itemView.getTop() + width, (float) itemView.getRight() - width, (float)itemView.getBottom() - width);
            c.drawBitmap(b, null, destination, p);

            super.onChildDraw(c, rv, vh, dx,dy, actionState, isCurrentlyActive);
        }
    }
};

这是我仍然得到的错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference

BitmapFactory.decodeResources返回一个null对象

0 个答案: