C#：绘制Winform窗体

Winform窗体缺少左上角效果：

 public void SetWindowRegion()
        {
            System.Drawing.Drawing2D.GraphicsPath FormPath;
            FormPath = new System.Drawing.Drawing2D.GraphicsPath();
            Rectangle rect = new Rectangle(0, 0, this.Width, this.Height);
            int diameter = 20;
            FormPath .AddRectangle(new Rectangle(rect.Location.X + diameter, rect.Location.Y, rect.Width - diameter, rect.Height));
            FormPath .AddRectangle(new Rectangle(rect.Location.X, rect.Location.Y + diameter, diameter, rect.Height - diameter));
                        path.CloseFigure();

            this.Region = new Region(FormPath);

        }

        protected override void OnResize(System.EventArgs e)
        {

            this.Region = null;

            SetWindowRegion();

        }        

参考：Winform窗体四圆角效果：

public void SetWindowRegion()

{

    System.Drawing.Drawing2D.GraphicsPath FormPath;

    FormPath = new System.Drawing.Drawing2D.GraphicsPath();

    Rectangle rect = new Rectangle(0, 22, this.Width, this.Height - 22);//this.Left-10,this.Top-10,this.Width-10,this.Height-10);                 

    FormPath = GetRoundedRectPath(rect, 30);

    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;

}

protected override void OnResize(System.EventArgs e)

{

    this.Region = null;

    SetWindowRegion();

}