c#制作窗体的淡入淡出效果

想制作一个窗体的淡入淡出效果：

用Windwos API可以解决这个问题：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace formdanru
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        [DllImport("user32.dll")]
        private static extern bool AnimateWindow(IntPtr hwnd, int dwTime, int dwFlags);
        const int AW_BLEND = 0x80000;
        const int AW_VER_POSITIVE = 0x0004;
        const int AW_HIDE = 0x10000;

        private void Form1_Load(object sender, EventArgs e)
        {
            AnimateWindow(this.Handle, 1000, AW_BLEND);
        }

        private void Form1_FormClosing(object sender, FormClosingEventArgs e)
        {
            AnimateWindow(this.Handle, 1000, AW_BLEND | AW_HIDE);
        }
    }
}