C#实现中间挖空的矩形，中间透明的矩形

　　　　　　　using (SolidBrush brush = new SolidBrush(Color.FromArgb(125, Color.Black)))
            {
                GraphicsPath path = new GraphicsPath();
                path.AddRectangle(pnlCut.Bounds);//添加要填充的矩形
                Region region = new Region(path);
                region.Exclude(_cellRect);//除去中间不需要填充的矩形
                g.FillRegion(brush, region);
            }