这个问题已经在这里有一个答案：
- 如何绘制一个圆角矩形的WinForms（.NET）？ 5个回答
我使用此代码，使表单没有边框样式：
this.FormBorderStyle = FormBorderStyle.None;
我需要在表格上圆边。
有一个简单的方法是什么？ 我该怎么做？
Answer 1:
看看这个： http://msdn.microsoft.com/en-us/library/system.windows.forms.control.region.aspx
Form类从Control类继承，所以尝试这样做，你有链接到窗体的区域属性上（和做它当然的形式事件），同一样品：
// This method will change the square button to a circular button by
// creating a new circle-shaped GraphicsPath object and setting it
// to the RoundButton objects region.
private void roundButton_Paint(object sender,
System.Windows.Forms.PaintEventArgs e)
{
System.Drawing.Drawing2D.GraphicsPath buttonPath =
new System.Drawing.Drawing2D.GraphicsPath();
// Set a new rectangle to the same size as the button's
// ClientRectangle property.
System.Drawing.Rectangle newRectangle = roundButton.ClientRectangle;
// Decrease the size of the rectangle.
newRectangle.Inflate(-10, -10);
// Draw the button's border.
e.Graphics.DrawEllipse(System.Drawing.Pens.Black, newRectangle);
// Increase the size of the rectangle to include the border.
newRectangle.Inflate( 1, 1);
// Create a circle within the new rectangle.
buttonPath.AddEllipse(newRectangle);
// Set the button's Region property to the newly created
// circle region.
roundButton.Region = new System.Drawing.Region(buttonPath);
}
Answer 2:
我知道这个问题已经回答了，我想补充一个替代的和愚蠢的但并不推荐做法，因为你的问题不限制答案应运而生代码...
- 创建你的背景颜色填充空白，正方形的图像，然后删除左上圆角是透明的，重复这各个角落
- 设置一个不太可能的颜色作为窗体背景颜色
- 设置这个颜色作为
TransparencyKey表单上 - 添加图像作为
PictureBox，并把它们对应的角落
中提琴！
Answer 3:
public static void RoundBorderForm(Form frm)
{
Rectangle Bounds = new Rectangle(0, 0, frm.Width, frm.Height);
int CornerRadius = 20;
System.Drawing.Drawing2D.GraphicsPath path = new System.Drawing.Drawing2D.GraphicsPath();
path.AddArc(Bounds.X, Bounds.Y, CornerRadius, CornerRadius, 180, 90);
path.AddArc(Bounds.X + Bounds.Width - CornerRadius, Bounds.Y, CornerRadius, CornerRadius, 270, 90);
path.AddArc(Bounds.X + Bounds.Width - CornerRadius, Bounds.Y + Bounds.Height - CornerRadius, CornerRadius, CornerRadius, 0, 90);
path.AddArc(Bounds.X, Bounds.Y + Bounds.Height - CornerRadius, CornerRadius, CornerRadius, 90, 90);
path.CloseAllFigures();
frm.Region = new Region(path);
frm.Show();
}
文章来源: Form with Rounded Borders in C#? [duplicate]
