C# 绘制圆角矩形

Graphics g = e.Graphics;

            // 圆角半径
            int cRadius = 1;  

            // 要实现 圆角化的 矩形
            Rectangle rect = new Rectangle(0, 0, panel4.Width - cRadius, panel4.Height - cRadius);

            // 指定图形路径， 有一系列 直线/曲线 组成
            GraphicsPath myPath = new GraphicsPath();
            myPath.StartFigure();
            myPath.AddArc(new Rectangle(new Point(rect.X, rect.Y), new Size(2 * cRadius, 2 * cRadius)), 180, 90);
            myPath.AddLine(new Point(rect.X + cRadius, rect.Y), new Point(rect.Right - cRadius, rect.Y));
            myPath.AddArc(new Rectangle(new Point(rect.Right - 2 * cRadius, rect.Y), new Size(2 * cRadius, 2 * cRadius)), 270, 90);
            myPath.AddLine(new Point(rect.Right, rect.Y + cRadius), new Point(rect.Right, rect.Bottom - cRadius));
            myPath.AddArc(new Rectangle(new Point(rect.Right - 2 * cRadius, rect.Bottom - 2 * cRadius), new Size(2 * cRadius, 2 * cRadius)), 0, 90);
            myPath.AddLine(new Point(rect.Right - cRadius, rect.Bottom), new Point(rect.X + cRadius, rect.Bottom));
            myPath.AddArc(new Rectangle(new Point(rect.X, rect.Bottom - 2 * cRadius), new Size(2 * cRadius, 2 * cRadius)), 90, 90);
            myPath.AddLine(new Point(rect.X, rect.Bottom - cRadius), new Point(rect.X, rect.Y + cRadius));
            myPath.CloseFigure();
            g.DrawPath(new Pen(Color.Red, 1), myPath);