在.net winform中创建圆角容器

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

public class RoundedContainer : Panel
{
    private int _cornerRadius = 10;

    public int CornerRadius
    {
        get { return _cornerRadius; }
        set { _cornerRadius = value; Invalidate(); }
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        using (var graphicsPath = new System.Drawing.Drawing2D.GraphicsPath())
        {
            graphicsPath.AddArc(0, 0, CornerRadius, CornerRadius, 180, 90);
            graphicsPath.AddArc(Width - CornerRadius, 0, CornerRadius, CornerRadius, 270, 90);
            graphicsPath.AddArc(Width - CornerRadius, Height - CornerRadius, CornerRadius, CornerRadius, 0, 90);
            graphicsPath.AddArc(0, Height - CornerRadius, CornerRadius, CornerRadius, 90, 90);

            Region = new Region(graphicsPath);
        }

        using (var pen = new Pen(Color.Gray, 2))
        {
            e.Graphics.DrawArc(pen, 0, 0, CornerRadius, CornerRadius, 180, 90);
            e.Graphics.DrawArc(pen, Width - CornerRadius, 0, CornerRadius, CornerRadius, 270, 90);
            e.Graphics.DrawArc(pen, Width - CornerRadius, Height - CornerRadius, CornerRadius, CornerRadius, 0, 90);
            e.Graphics.DrawArc(pen, 0, Height - CornerRadius, CornerRadius, CornerRadius, 90, 90);
        }
    }
}