如何使用C#绘制一个圆角窗体

您可以使用C#的Graphics类来绘制一个圆角窗体，以下是一个简单的示例代码：

using System;
using System.Drawing;
using System.Windows.Forms;

public partial class RoundForm : Form
{
    public RoundForm()
    {
        InitializeComponent();
        this.FormBorderStyle = FormBorderStyle.None;
        this.BackColor = Color.White;
        this.DoubleBuffered = true;
        this.SetStyle(ControlStyles.ResizeRedraw, true);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        Graphics graphics = e.Graphics;
        graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

        Rectangle rectangle = this.ClientRectangle;
        rectangle.Width--;
        rectangle.Height--;

        graphics.DrawRoundRectangle(new Pen(Color.Gray), rectangle, 20);
    }
}

public static class GraphicsExtensions
{
    public static void DrawRoundRectangle(this Graphics graphics, Pen pen, Rectangle rectangle, int radius)
    {
        GraphicsPath path = new GraphicsPath();
        path.AddLine(rectangle.Left + radius, rectangle.Top, rectangle.Right - radius, rectangle.Top);
        path.AddArc(rectangle.Right - radius, rectangle.Top, radius, radius, 270, 90);
        path.AddLine(rectangle.Right, rectangle.Top + radius, rectangle.Right, rectangle.Bottom - radius);
        path.AddArc(rectangle.Right - radius, rectangle.Bottom - radius, radius, radius, 0, 90);
        path.AddLine(rectangle.Right - radius, rectangle.Bottom, rectangle.Left + radius, rectangle.Bottom);
        path.AddArc(rectangle.Left, rectangle.Bottom - radius, radius, radius, 90, 90);
        path.AddLine(rectangle.Left, rectangle.Bottom - radius, rectangle.Left, rectangle.Top + radius);
        path.AddArc(rectangle.Left, rectangle.Top, radius, radius, 180, 90);
        path.CloseFigure();

        graphics.DrawPath(pen, path);
    }
}

这个示例使用了一个自定义的GraphicsExtensions类，其中包含了一个绘制圆角矩形的方法。在RoundForm类的OnPaint方法中，我们使用该方法绘制了一个圆角矩形作为窗体的边框。