C#实现圆角窗体API方法详解

        /// <summary>
        /// 圆角：radius=圆角弧度   rect是要做圆角的矩形
        /// </summary>
        public void SetWindowRegion(int width, int height)
        {
            System.Drawing.Drawing2D.GraphicsPath FormPath;
            FormPath = new System.Drawing.Drawing2D.GraphicsPath();
            Rectangle rect = new Rectangle(0, 0, width, height);
            FormPath = GetRoundedRectPath(rect, 8);
            this.Region = new Region(FormPath);
        }
        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();
            return path;
        }