如何在LayerDrawable中移动ChildDrawable

Question

以下是我的代码

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_test_layer_drawable2);
    ImageView i = (ImageView) findViewById(R.id.i);
    LayerDrawable ld = new LayerDrawable(new Drawable[]{dra(this, R.drawable.ic_insert_drive_file_black_48dp), new Rect()});
    ld.setLayerInsetTop(1, 200);
    ld.setLayerInsetLeft(1, 200);
    i.setImageDrawable(ld);
}

这里是Rect

class Rect extends Drawable {
        Context c;

        @Override
        public void draw(Canvas canvas) {
            c = getApplicationContext();
            Paint p = new Paint();
            p.setStrokeWidth(2);
            p.setStyle(Paint.Style.STROKE);
            p.setColor(col(c, R.color.colorAccent));
            canvas.drawRect(100, 100, 200, 200, p);
        }

        @Override
        public void setAlpha(int alpha) {

        }

        @Override
        public void setColorFilter(ColorFilter colorFilter) {

        }

        @Override
        public int getOpacity() {
            return 0;
        }
    }

输出为：

​

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我希望把矩形移到ImageView的右下角，怎么做呢？

当我使用setLayerInsetTop时，它只改变矩形的大小