@Override
        public void draw(Canvas canvas, Paint paint) {
            canvas.drawCircle(mCenterX, mCenterY, mRadius, mShadowPaint);
            canvas.drawCircle(mCenterX, mCenterY, mRadius - mShadowRadius, paint);
        }
Returns the RectF that defines this rectangle's bounds.
caprice/ui/src/main/java/net/qiujuer/genius/ui/widget/FloatActionButton.java