c#怎么设计窗口圆角

<code class="csharp">using System.Drawing;
using System.Windows.Forms;</code>

<code class="csharp">public class RoundedForm : Form
{
    [DllImport("Gdi32.dll")]
    private static extern bool RoundRect(IntPtr hWnd, int nLeftRect, int nTopRect, int nRightRect, int nBottomRect, int nWidthEllipse, int nHeightEllipse);

    protected override void OnResize(EventArgs e)
    {
        base.OnResize(e);

        // 窗口半径
        int radius = 20;

        // 确定窗口圆角区域
        Region region = new Region();
        GraphicsPath path = new GraphicsPath();
        path.AddRoundRect(new Rectangle(0, 0, Size.Width, Size.Height), radius, radius);
        region.RegionPath = path;

        // 将圆角区域应用到窗口
        Region = region;
    }
}</code>

<code class="csharp">RoundedForm form = new RoundedForm();
form.Text = "窗口圆角示例";
form.Size = new Size(400, 400);
form.ShowDialog();</code>