Fade in and fade out function of C form (project source code)

Let's see the effect first , I think it's OK

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
             // Fade out effect hidden 
            if (Win32.AnimateWindow(this.Handle, 2300, Win32.AW_BLEND | Win32.AW_HIDE)) {
                // Fade in effect display 
                Win32.AnimateWindow(this.Handle, 2300, Win32.AW_BLEND | Win32.AW_ACTIVATE);
            }

        }
       
    }


     public class Win32
    {
        /// <summary>
        ///  Perform animation 
        /// </summary>
        /// <param name="whnd"> control handle </param>
        /// <param name="dwtime"> Animation time </param>
        /// <param name="dwflag"> Animation combination name </param>
        /// <returns>bool value , Whether the animation is successful </returns>
        [DllImport("user32.dll")]
        public static extern bool AnimateWindow(IntPtr whnd, int dwtime, int dwflag);
 
        /// <summary>
        ///  From left to right 
        /// </summary>
        public const Int32 AW_HOR_POSITIVE = 0x00000001;
        /// <summary>
        ///  Right to left display 
        /// </summary>
        public const Int32 AW_HOR_NEGATIVE = 0x00000002;
        /// <summary>
        ///  Display from top to bottom 
        /// </summary>
        public const Int32 AW_VER_POSITIVE = 0x00000004;
        /// <summary>
        ///  Show... From bottom to top 
        /// </summary>
        public const Int32 AW_VER_NEGATIVE = 0x00000008;
        /// <summary>
        ///  If used AW_HIDE sign , Make the window overlap inward , Shrink window ; Otherwise, make the window expand outward , That is, expand the window 
        /// </summary>
        public const Int32 AW_CENTER = 0x00000010;
        /// <summary>
        ///  Hidden window , By default, the window is displayed 
        /// </summary>
        public const Int32 AW_HIDE = 0x00010000;
        /// <summary>
        ///  Activate window . In the use of the AW_HIDE This sign cannot be used after the sign 
        /// </summary>
        public const Int32 AW_ACTIVATE = 0x00020000;
        /// <summary>
        ///  Use sliding type . The default is scroll animation type . When using AW_CENTER When marking , This sign is ignored 
        /// </summary>
        public const Int32 AW_SLIDE = 0x00040000;
        /// <summary>
        ///  Transparency from high to low 
        /// </summary>
        public const Int32 AW_BLEND = 0x00080000;
    }

}