WinForm 窗体圆角实现

        /// 

        /// 设置窗体的Region
        /// 
        public void SetWindowRegion()
        {
            GraphicsPath FormPath;
            Rectangle rect = new Rectangle(0, 0, this.Width, this.Height);
            FormPath = GetRoundedRectPath(rect, 50);
            this.Region = new Region(FormPath);

        }
        /// 

        /// 绘制圆角路径
        /// 
        /// 
        /// 
        /// 
        private GraphicsPath GetRoundedRectPath(Rectangle rect, int radius)
        {
            int diameter = radius;
            Rectangle arcRect = new Rectangle(rect.Location, new Size(diameter, diameter));
            GraphicsPath path = new GraphicsPath();

            // 左上角
            path.AddArc(arcRect, 180, 90);

            // 右上角
            arcRect.X = rect.Right - diameter;
            path.AddArc(arcRect, 270, 90);

            // 右下角
            arcRect.Y = rect.Bottom - diameter;
            path.AddArc(arcRect, 0, 90);

            // 左下角
            arcRect.X = rect.Left;
            path.AddArc(arcRect, 90, 90);
            path.CloseFigure();//闭合曲线
            return path;
        }

        /// 

        /// 窗体size发生改变时重新设置Region属性
        /// 
        /// 
        /// 
        private void Form1_Resize(object sender, EventArgs e)
        {
            SetWindowRegion();
        }

 public Form1()
        {
            InitializeComponent();

            this.BackColor = ColorTranslator.FromHtml("#F7F1F1");
            this.TransparencyKey =     ColorTranslator.FromHtml("#F7F1F1");
            this.label1.BackColor = Color.White;
            this.Opacity = 1;
        }