WinForm 窗体圆角、平角（不规则窗体）实现的几种方法

以下代码均是写在partial class Form1 : Form{}代码块之间，废话不多说直接上代码。

第一种方法是通过OnResize方法来实现 

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, 10);
    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();
}

第二种方法是通过Point方法来实现

private SetFormCircle()
{
    int radian = 4; //圆弧角的比率，可以自己改变这个值看具体的效果
    int w = this.Width; //窗体宽
    int h = this.Height; //窗体高
 
    //对于矩形的窗体，要在一个角上画个弧度至少需要2个点，所以4个角需要至少8个点
    Point p1 = new Point(radian, 0);
    Point p2 = new Point(w - radian, 0);
    Point p3 = new Point(w, radian);
    Point p4 = new Point(w, h - radian);
    Point p5 = new Point(w - radian, h);
    Point p6 = new Point(radian, h);
    Point p7 = new Point(0, h - radian);
    Point p8 = new Point(0, radian);
 
    System.Drawing.Drawing2D.GraphicsPath shape = new System.Drawing.Drawing2D.GraphicsPath();
 
    Point[] p = new Point[] { p1, p2, p3, p4, p5, p6, p7, p8 };
    shape.AddPolygon(p);
 
    //将窗体的显示区域设为GraphicsPath的实例
    this.Region = new System.Drawing.Region(shape);
}
private void Form1_Load(object sender, EventArgs e)
{
    SetFormCircle();
}
 
private void Type(Control sender, int p_1, double p_2)
{
    GraphicsPath oPath = new GraphicsPath();
    oPath.AddClosedCurve(
        new Point[] {
            new Point(0, sender.Height / p_1),
            new Point(sender.Width / p_1, 0), 
            new Point(sender.Width - sender.Width / p_1, 0), 
            new Point(sender.Width, sender.Height / p_1),
            new Point(sender.Width, sender.Height - sender.Height / p_1), 
            new Point(sender.Width - sender.Width / p_1, sender.Height), 
            new Point(sender.Width / p_1, sender.Height),
            new Point(0, sender.Height - sender.Height / p_1) },
 
        (float) p_2);
 
    sender.Region = new Region(oPath);
}
//备注：在窗体的paint和resize事件中增加:Type(this,20,0.1);
//(参数20和0.1也可以根据自己的需要调整到最佳效果)